DE102011012730B4 - Shock absorbers - Google Patents

Abstract

A shock absorber comprising: a cylinder (10) in which an operating fluid is enclosed; a piston (11) slidably fitted in the cylinder (10) and configured to divide an interior of the cylinder (11) into two chambers (12 , 13); a piston rod (16) connected to the piston (11) and configured to extend out of the cylinder (10); first and second conduits (30a, 30b, 110, 111) from which the operating fluid flows out from one of the chambers (12, 13) of the interior of the cylinder (10) due to the movement of the piston (11); a damping force generating mechanism (32b) disposed in the first conduit (30a, 30b) and is configured to generate a damping force; a housing (55) in which a flow conduit corresponding to at least a portion of the second conduit (110, 111) is formed; a free piston (57) movable in the housing ( 55) is arranged and is designed to the second line (110, 111) in egg to divide an upstream side and a downstream side; andone or more elastic bodies (58) disposed between the free piston (57) and the housing (55), wherein a free piston contact surface of the free piston (57) with which the elastic body (58) is in contact and / or a Housing contact surface of the housing (55) with which the elastic body (58) is in contact includes an inclined surface inclined in a moving direction of the free piston (57) and a shortest distance between a portion in contact with the elastic Body (58) stands within the free piston contact surface, and a portion which is in contact with the elastic body (58) within the housing contact surface is changed due to the movement of the free piston (57).

Description

BACKGROUND OF THE INVENTION

Field of the invention

The present invention relates to a shock absorber.

Description of the related art

In some shock absorbers, a damping force characteristic changes in response to a vibration state (see, for example, Japanese Unexamined Utility Model Application, First Publication No. JP H07-19 642 U).

In general, when a damping force characteristic changes in response to a vibration state, shock absorbers are required to set characteristics, for example, to make the damping force characteristic smoothly.

The DE 40 36 613 A1 , U.S. 5,248,014 A and JP 2006 - 336 816 A form further state of the art.

SUMMARY OF THE INVENTION

The present invention is directed to providing a shock absorber capable of adjusting characteristics, for example, more smoothly, thereby changing a damping force characteristic in response to a vibration state.

According to a first aspect of the present invention, there is provided a shock absorber in which a free piston surface of a free piston with which an elastic body is in contact and / or the housing contact surface of a housing with which the elastic body is in contact is an inclined surface which is inclined in a moving direction of the free piston. A shortest distance between a portion of the free piston contact surface that is in contact with the elastic body and a portion of the housing contact surface that is in contact with the elastic body is changed by the movement of the free piston.

According to a second aspect of the present invention, there is provided a shock absorber including a moving direction deformation range in which the elastic body undergoes elastic deformation in a moving direction of the free piston at a downstream end within a moving range of the free piston. Further, the shock absorber includes a moving range in which the elastic body moves in the moving direction of the free piston in the state in which the elastic body is in contact with both the housing and the free piston at a position separated from the downstream end.

According to a third aspect of the present invention, there is provided a shock absorber comprising first and second conduits from which the operating fluid flows out of one of the chambers of the interior of the cylinder due to the movement of the piston, a damping valve disposed in the first conduit and regulates a flow of the operating fluid generated by sliding the piston to generate a damping force and a free piston disposed in the second conduit and dividing the second conduit into an upstream side and a downstream side. A conduction area varying mechanism that makes a conduction area of the second conduit adjustable is disposed in the second conduit.

According to the aspects of the present invention, the shock absorber can smoothly change the damping force.

Figure list

• 1 Fig. 13 is a cross-sectional view showing a shock absorber according to a first embodiment of the present invention.
• 2 Fig. 13 is a cross-sectional view showing important parts of the shock absorber according to a first embodiment of the present invention.
• 3 Fig. 13 is a characteristic diagram showing a characteristic of a load plotted against a free piston displacement of an O-ring in the shock absorber according to a first embodiment of the present invention.
• 4th Fig. 13 is a characteristic diagram showing a characteristic of a damping force plotted against a piston stroke in the shock absorber according to a first embodiment of the present invention.
• 5 Fig. 13 is a cross-sectional view showing important parts of a shock absorber according to a second embodiment of the present invention.
• 6A Fig. 13 is a cross-sectional view showing important parts of a shock absorber according to a third embodiment of the present invention.
• 6B Fig. 13 is a bottom view showing a damping force varying mechanism of the shock absorber according to a third embodiment of the present invention.
• 7A Fig. 13 is a cross-sectional view showing a modification of the important parts of the shock absorber according to a third embodiment of the present invention.
• 7B Fig. 13 is a cross-sectional view showing another modification of the important parts of the shock absorber according to a third embodiment of the present invention.
• 7C Fig. 13 is a cross-sectional view showing another modification of the important parts of the shock absorber according to a third embodiment of the present invention.
• 8th Fig. 13 is a cross-sectional view showing important parts of a shock absorber according to a fourth embodiment of the present invention.
• 9 Fig. 13 is a cross-sectional view showing important parts of a shock absorber according to a fifth embodiment of the present invention.
• 10 Fig. 13 is a cross-sectional view showing important parts of a shock absorber according to a sixth embodiment of the present invention.
• 11 Fig. 13 is a cross-sectional view showing a shock absorber according to a seventh embodiment of the present invention.
• 12A Fig. 13 is a main cross-sectional view showing important parts of the shock absorber according to a seventh embodiment of the present invention.
• 12B FIG. 14 is a cross-sectional view showing a shock absorber according to a seventh embodiment of the present invention, taken along line XX of FIG 12A with respect to a piston holding member and an opening area varying member body.
• 13th Fig. 3 is a cross-sectional view showing important parts of a shock absorber according to an eighth embodiment of the present invention.
• 14th Fig. 3 is a cross-sectional view showing important parts of a shock absorber according to a ninth embodiment of the present invention.
• 15th Fig. 3 is a cross-sectional view showing important parts of a shock absorber according to a tenth embodiment of the present invention.
• 16 Fig. 3 is a cross-sectional view showing important parts of a shock absorber according to an eleventh embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments described below are not limited to the content entitled “Summary of the Invention” and solve various problems to produce effects. The main problems to be solved by the following embodiments are enumerated below, including the content described in the section labeled “Summary of the Invention”.

[Improvement of Characteristics] When a damping force characteristic (a damping force relative to a piston speed) is changed in response to a vibration state, characteristic setting including a smoother change in the damping force characteristic is needed. This is based on the following reasons. When a characteristic of generating a low damping force and a characteristic of generating a high damping force are changed abruptly, a damping force is actually generated and also changed abruptly. For this reason, ride comfort of a vehicle deteriorates. In particular, when the change in the damping force occurs during steering of the vehicle, the movement of the vehicle becomes unstable and there is a possibility of causing inconvenience to a driver in steering. Therefore, as in Japanese Unexamined Utility Model Application, First Publication No. H07-019642 disclosed, the characteristic curve setting of the smoother change is checked, but an additional characteristic curve improvement is desired.

[Restriction on increase in size] As in Japanese Unexamined Utility Model Application, First Publication No. H07-019642 disclosed, a variety of cylinder devices in which an improvement has been attempted so that a damping force characteristic covering a wide range of vibration frequencies is obtained in such a way that a free piston on the side of one end of the Piston is arranged and moves up and down in a housing, in addition to a piston which divides the interior of a cylinder into two chambers and has a mechanism for generating a damping force. Thereby, a damping force characteristic which covers a wide range of vibration frequencies is obtained in the cylinder devices. An increase in the axial length is cited as a problem common to these cylinder devices since a range in which the free piston moves up and down is required. When the cylinder device is enlarged, a degree of arrangement freedom becomes a vehicle body reduced. For this reason, the increase in the axial length of the cylinder device is a significant problem.

[Reduction of the number of parts] As in Japanese Unexamined Utility Model Application, First Publication No. H07-019642 discloses that since components such as a housing or a free piston are provided in addition to a piston, the number of components increases. If the number of parts increases, it has an impact on productivity, durability, reliability, and so on. Therefore, it is necessary to reduce the number of components while obtaining a desired characteristic, that is, a damping force characteristic which covers a wide range of vibration frequencies. In the following, each embodiment of the present invention will be described with reference to the drawings.

[First embodiment]

A first embodiment of the present invention will be described with reference to FIG 1 to 4th described. In order to facilitate understanding of the following description, a lower side of the figure is set as one side and, in turn, an upper side of the figure is set as the other side.

As in 1 As shown, a shock absorber of the first embodiment is a single-tube type hydraulic shock absorber and comprises a bottomed cylindrical cylinder 10 in which an oil is included as an operating fluid. A piston 11 is slidable in the cylinder 10 fitted and the cylinder 10 is from the piston 11 divided into two chambers, ie, an upper chamber 12th and a lower chamber 13th . The piston 11 is made of a piston body 14th , an annular sliding element 15th on an outer peripheral surface of the piston body 14th is arranged, and an insertion portion of a piston rod 16 that go with the piston body 14th is connected, the insertion portion in the piston body 14th is introduced, trained.

The piston body 14th is formed by sintering and is with one end of the piston rod 16 connected. The other end of the piston rod 16 is made by a rod guide 17th and an oil seal 18th attached to an opening side of the cylinder 10 is attached, inserted and extends outwardly of the cylinder 10 .

The piston rod 16 includes a main shaft portion 20th and an attachment shaft portion 21 which has a smaller diameter than the main shaft section 20th having. The piston body 14th is at one end of the mounting stem portion 21 attached. A section of the main shaft section 20th the piston rod 16 between the piston body 14th and the rod guide 17th is with a rebound stopper 24 (rebound stopper) and a buffer 25th provided in which the piston rod 16 is introduced. A subdivision 26th for dividing the lower chamber 13th on the side of the piston 11 is slidable in the cylinder 10 on a side that is closer to a bottom of the cylinder 10 is than the piston 11 , arranged. Oil is in the upper and lower chambers 12th and 13th of the cylinder 10 locked and in a chamber 27 by the lower chamber 13th by means of the subdivision 26th is separated, a high pressure gas is included (about 20 to 30 atm). For example, one side of the aforementioned damper is supported by the structure of a vehicle, and one side of the wheel is attached to the other side of the shock absorber. In contrast, the other side of the shock absorber can be supported by the vehicle body and the wheel side can be attached to one side of the shock absorber. When the vehicle vibrates while traveling, positions of the cylinder become 10 and the piston rod 16 changed by such a vibration relative to each other. This change is due to the fluid resistance of a flow conduit running in the first piston 11 is formed, suppressed. As will be described in detail below, the fluid resistance is the flow conduit that is in the first piston 11 is configured to be varied by a speed or amplitude of the vibration, so that the ride comfort is improved by suppressing the vibration. In addition to the vibration generated by the wheel, an initial force or centrifugal force generated by the vehicle body while traveling is also between the cylinder 10 and the piston rod 16 created. For example, a traveling direction is changed by steering, and hence centrifugal force is generated from the vehicle body. A force based on this centrifugal force is generated between the cylinder 10 and the piston rod 16 created. As will be described later, the shock absorber of the present invention provides good characteristics with respect to vibration based on the force generated by the vehicle body during travel of the vehicle and ensures high stability associated with travel of the vehicle.

As in 2 shown is the piston body 14th with a plurality of lines (first lines) 30a (only one of them is in 2 as shown in cross-sectional view) by what oil in connection with the movement of the piston 11 towards the upper chamber 12th from the upper chamber 12th towards the lower chamber 13th flows, that is, an extension stroke, and a plurality of pipes (first pipes) 30b (only one of them is in 2 as shown in cross-sectional view) through which oil is associated with the movement of the piston 11 towards the lower chamber 13th from the lower chamber 13th out to the upper chamber 12th flows, ie, a displacement stroke; both allow the upper chamber 12th and the lower chamber 13th to be related to each other. The lines 30a which form half of these lines are formed at an equal pitch in a circumferential direction, each having a line 30b between any two of the lines 30a is arranged. One axial side of the piston 11 (a top of 1 ) is open to an outside in a radial direction and the other axial side of the piston 11 (a lower page of 1 ) is open inward in a radial direction. Alternatively, the lines 30a and 30b outside the cylinder 10 be formed by, for example, tubes.

Further is a damping force generating mechanism 32a to generate a damping force in half 30a these lines arranged. The damping force generating mechanism is on the side of the lower chamber 13th in the axial direction of the piston 11 arranged and is on the attachment shaft portion 21 the piston rod 16 attached. The lines 30a form extension lines through which the oil flows when the piston moves 11 moved towards the extension side when the piston rod 16 out of the cylinder 10 moves and the damping force generating mechanism 32a provided for these lines forms an extension side damping force mechanism that controls the flow of oil on the extension side lines 30a regulated to create a damping force.

The lines 30b forming the remaining half are formed at an equal interval in a circumferential direction, with each lead 30a between any two of the lines 30b is arranged. The other axial side of the piston 11 (a lower page of 1 ) is open to the outside in a radial direction and one axial side of the piston 11 (an upper page of 1 ) is opened toward the inside in a radial direction.

A damping force generating mechanism 32b to generate a damping force is in the remaining half 30b these lines arranged. The damping force generating mechanism 32b is on the side of the upper chamber 12th in the axial direction of the piston 11 arranged and is on the attachment shaft portion 21 the piston rod 16 attached. The lines 30b form displacement side lines through which oil flows when the piston moves 11 towards the displacement side when the piston rod moves 16 himself in the cylinder 10 moves, and the damping force generating mechanism 32b provided for these lines forms a displacement side damping force generating mechanism that controls the flow of oil of the displacement side lines 30b controls to generate a damping force.

A damping force varying mechanism 35 is on the piston rod 16 at one end of the mounting stem portion 21 attached, which is even further away from the piston 11 is.

The piston body 14th has a substantially disc shape and is single-hole 38 provided in the center thereof which is in an axial direction and in which the fastening shaft portion 21 the piston rod 16 is introduced.

At the end of the piston body 14th , on the side of the lower chamber 13th , is a seat section 41a , which is the damping force generating mechanism 32a forms at the openings of one end of the extension side ducts 30a formed in an annular shape. At the end of the piston body 14th , on the side of the upper chamber 12th , is a seat section 41b , which is the damping force generating mechanism 32b forms at the openings of one end of the displacement side lines 30b formed in an annular shape.

The piston body 14th is with an annular step portion 42b provided, which has a smaller axial height than the seat portion 41a on the opposite side of the seat section 41a to the filling hole 38 having. The other ends of the extension side pipes 30b are at a position of the step section 42b open. The seat section 41a is with line grooves (openings) 43a provided which are recessed in an axial direction in order to move outwards from the respective lines 30a in a radial direction of the piston 11 to extend to the step section 42b to run away. The piston body is similar 14th with an annular step portion 42a provided, which has a lower axial height than the seat portion 41b on the opposite side of the seat section 41b to the insertion hole 38 has off. The other ends of the extension side pipes 30a are at a position of the step portion 42a open. Further, although not shown, is the seat portion 41b also provided with line grooves (openings) which are recessed in an axial direction in order to emerge outwards from the respective lines 30b in a radial direction of the piston 11 to extend to the step section 42a to run away.

The damping force generating mechanism 32a includes an annular disc valve 45a that is on the entire seat section 41a can sit on at the same time, an annular spacer 46a , which has a smaller diameter than the disc valve 45a and the one at the opposite side of the butterfly valve 45a to the piston body 14th is arranged, and an annular valve regulating member 47a that has a larger diameter than the spacer 46a and on the opposite side of the spacer 46a to the piston main body 14th is arranged. The butterfly valve 45a is formed by superposing a plurality of annular disks. The butterfly valve 45a is from the seat section 41a separated, making the lines 30a be opened. The valve regulating element 47a regulates the deformation of the butterfly valve 45a when it exceeds a normal range in an opening direction. The butterfly valve 45a is on the lines 30a arranged and serves as a damping valve that regulates the flow of oil, which is caused by sliding the piston 11 is achieved to produce a damping force.

Similarly, the damping force generating mechanism includes 32b an annular disc valve 45b that is on the entire seat section 41b can sit on at the same time, an annular spacer 46b , which has a smaller diameter than the disc valve 45b and the one on the opposite side of the butterfly valve 45b to the piston body 14th is arranged and an annular valve regulating element 47b , which has a larger diameter than the spacer 46b and on the opposite side of the spacer 46b to the piston body 14th is arranged. The valve regulating element 47b is in contact with a shaft step portion 48 at the end of the main shaft section 20th the piston rod 16 on the side of the fastening shaft section 21 . The butterfly valve 45b is formed by superposing a plurality of annular disks. The butterfly valve 45b is from the seat section 41b separated, making the lines 30b be opened. The valve regulating element also regulates 47b the deformation of the butterfly valve 45b when it exceeds a normal range in an opening direction. The butterfly valve 45b is on the lines 30b arranged and serves as a damping valve that controls the flow of oil by sliding the piston 11 is regulated to generate a damping force.

In the present embodiment, the damping force generating mechanism 32a or 32b shown as an inner peripheral clamp disc valve as an example. However, the damping force generating mechanism is not limited to this, and may be any mechanism that generates a damping force. For example, the disc valve may be a lift-type valve that is biased by means of a coil spring, or a poppet valve.

A male thread 50 is at a leading end of the piston rod 16 educated. The damping force varying mechanism 35 (a frequency sensitive part) which varies a damping force without being externally controlled by means of a frequency (a vibration state) is applied to the male thread 50 screwed. The damping force varying mechanism 35 is from one housing 55 that is a cover element 53 and a case body 54 has, a free piston 57 that is slidable into the housing 55 fitted, a displacement-side O-ring (an elastic body that is an elastic body) 58 that between the free piston 57 and the cover element 53 of the housing 55 is arranged, and a deformation by compression (English: compression deformation) experiences when the free piston 57 moves in one direction, and an extension side O-ring (one elastic body, the other elastic body) 59 that between the free piston 57 and the case body 54 of the housing 55 is arranged and which experiences a deformation by compression when the piston 57 moved in the other direction, formed. The cover element 53 is with a female thread 52 provided into which the male thread 50 the piston rod 16 is screwed in. The case body 54 has a bottomed cylindrical shape and is on the lid member 53 attached so that an opening side of the case body 54 closed is. Furthermore, in 2 the O-rings 58 and 59 Shown in a natural state for convenience.

Especially since the O-ring 59 serves as a seal, becomes the O-ring 59 preferably arranged to be deformed normally in an attached state (a non-circular cross section). The O-ring 58 serves as a resistance element that is subjected to compression deformation when the free piston 57 moves in one direction and creates resistance to the displacement of the free piston 57 . The O-ring 59 serves as a resistance element that is subjected to compression deformation when the free piston 57 moves in the other direction and creates displacement resistance on the free piston 57 .

As the cover element 53 , which is formed predominantly by cutting, comprises the cover element 53 , a lid cylinder portion (an extension portion) 62 having an approximately cylindrical shape, and a disc-shaped lid flange portion 63 extending from one axial end of the lid cylinder portion 62 extends in a radially outward direction.

The female thread 52 is on an inner periphery of the lid cylinder portion 62 formed and extends inwardly from a axial intermediate position of the cover cylinder section 62 towards an end position of the cover cylinder section 62 , which the lid flange section 63 opposite. A step section 66 is on an outer periphery of the lid cylinder portion 62 on the opposite side of the cover flange section 63 educated. A cylindrical surface section 67 and a curved surface portion 68 are on an outer peripheral surface of the lid cylinder portion 62 on the side closer to the lid flange portion 63 is as the stage section 66 educated. The cylindrical surface section 67 has a constant diameter and the curved surface portion 68 , the one with the cylindrical surface section 67 is formed in an annular shape so that its diameter with the distance to the cylindrical surface portion 67 rises in an axial direction and is with a flange surface portion 69 of the cover flange section 63 on the side of the lid cylinder section 62 connected. The curved surface section is formed so that its cross section comprises a central axis of the cover element 53 has an arcuate shape.

The case body 54 is mainly formed by cutting. The case body 54 includes a housing cylinder portion 75 , which has an approximately cylindrical shape and a housing bottom portion 76 , the one axial end of the housing cylinder portion 75 locks.

An inner annular protrusion 80 (a case-side annular projection) having an annular shape extending in a radial direction in an inward direction is on an inner circumference of one end of the case cylinder portion 75 on one side of the housing bottom section 76 educated. A section of surface with a small diameter 81 , a tapered surface portion (an inclined surface) 82, a curved surface portion (an inclined surface) 83, a cylindrical surface portion with a large diameter 84 , and a fitted cylindrical surface portion with a large diameter 85 are in turn on the inner periphery of the housing cylinder portion 75 starting at the side of the case bottom section 76 educated. The small diameter cylindrical surface portion 81 has a constant diameter. The sloped surface section 82 , the one with the cylindrical surface portion with a small diameter 81 is connected, is formed so that its diameter with the distance to the cylindrical surface portion with a small diameter 81 increases. The curved surface section 83 , the one with the beveled surface section 82 is formed in an annular shape so that its diameter with the distance to the tapered surface portion 82 increases. The large diameter cylindrical surface portion 84 , the one with the curved surface section 83 is connected has a constant diameter that is larger than a diameter of the cylindrical surface portion with a small diameter 81 . The fitted cylindrical surface section 85 that is adjacent to the large diameter cylindrical surface portion 84 located in an axial direction has a larger diameter than the cylindrical large diameter surface portion 84 on. The curved surface section 83 is designed so that its cross section includes a central axis of the housing body 84 has an arcuate shape. The small diameter cylindrical surface portion 81 , the beveled surface section 82 and the curved surface portion 83 are on the inner annular protrusion 80 educated.

Heretofore, the housing has been described as a cylinder, although the inner peripheral surface thereof preferably has a circular cross section, the outer peripheral surface thereof may have a non-circular cross section such as a polygonal cross section.

The cover element 53 is inserted into the case body from the opening side of the case body 54 inserted, the lid cylinder portion 62 is directed in a direction. At this point, the cover element leads 53 to the fact that the lid flange section 63 into the fitted cylindrical surface section 85 is fitted. In this state, the opening end of the housing cylinder portion becomes 75 pressed inwards. This becomes the cover element 53 on the case body 54 attached as a single body, making the housing 55 is trained. The case bottom section 76 is provided with a communication hole (opening) 87 at the center thereof which extends therethrough in an axial direction.

The free piston 57 is mainly formed by cutting. The free piston 57 includes a piston cylinder portion (a cylinder portion) 91 with an approximately cylindrical shape, a piston crown portion 92 , the one axial end of the piston cylinder portion 91 closes and a piston flange section (flange section) 94 , which has an outer annular (a piston-side annular projection) 93 having an annular shape extending outwardly from the other axial end of the piston cylinder portion 91 extends in a radial direction.

A cylindrical surface section with a small diameter 97 , a curved surface section (an inclined surface) 98 , a sloped surface portion (an inclined surface) 99 and a large diameter cylindrical surface portion 100 are in turn on outer peripheral surfaces of the piston cylinder portion 91 and the piston flange portion 94 starting from the side of the piston crown section 92 educated. The small diameter cylindrical surface portion 97 is on the piston cylinder portion 91 educated. The curved surface section 98 , the beveled surface section 99 and the large-diameter cylindrical surface portion 100 are on the piston flange portion 94 educated. The small diameter cylindrical surface portion 97 has a constant diameter and the curved surface portion 98 , the one with the cylindrical surface portion with a small diameter 97 is formed in an annular shape so that its diameter increases as well as the distance to the cylindrical surface portion with a small diameter 97 increases. The sloped surface section 99 , the one with the curved surface section 98 is connected, is formed so that its diameter increases, as well as the distance to the curved surface portion 98 increases. The large diameter cylindrical surface portion 100 , the one with the beveled surface section 99 is connected has a constant diameter that is larger than a diameter of the cylindrical surface portion with a small diameter 97 . The curved surface section 98 is designed so that its cross section includes a central axis of the free piston 57 has an arcuate shape.

A cylindrical surface section 102 and a tapered surface portion (an inclined surface) 103 are in turn on an inner peripheral surface of the piston cylinder portion 91 starting at the piston crown section 92 educated. The cylindrical surface section 102 on the side of the piston crown section 92 is on the piston cylinder portion 91 educated. Both the cylindrical surface section 102 on the opposite side of the piston crown section 92 as well as the inclined surface section 103 are on the piston flange portion 94 educated. The cylindrical surface section 102 has a constant diameter and the tapered surface portion 103 , the one with the cylindrical surface section 102 is connected, is formed so that its diameter with the distance therefrom to the cylindrical surface portion 102 increases.

The piston crown section 92 on the opposite side of the piston cylinder section 91 is with an exempt section 104 provided at the center thereof recessed in an axial direction.

The large diameter cylindrical surface portion 100 of the free piston 57 is slidable in the large diameter cylindrical surface portion 84 of the housing body 54 fitted. Further, the cylindrical surface portion is of a small diameter 97 of the free piston 57 slidable in the small diameter cylindrical surface portion 81 of the housing body 54 fitted. In this state are a position of the inclined surface portion 82 of the housing body 54 and a position of the curved surface portion 98 of the free piston 57 superposed on each other in radial directions thereof and a position of the curved surface portion 83 of the housing body 54 and a position of the tapered surface portion 99 of the free body 57 are superposed on each other in radial directions thereof. As a result, both the inclined surface portion lie 82 and the curved surface portion 83 of the housing body 54 both the curved surface section 98 as well as the inclined surface section 99 of the free piston 57 in a direction of movement of the free piston 57 opposite each other. The flange surface portion is also located 96 of the cover element 53 opposite to the inclined surface section 103 of the free piston 57 in a direction of movement of the free piston 57 . The sloped surface section 82 of the housing body 54 and the tapered surface portion 99 of the free piston 57 are inclined at the same angle to the axes thereof. The curved surface section 98 of the free piston 57 has the same cross-sectional curvature as the curved surface portion 83 of the housing body 54 on. Furthermore, the surface sections 83 and 98 Radii of curvature with a larger cross-sectional radius than the O-ring 59 , which has the circular cross-section.

Hence the O-ring 59 between the small diameter cylindrical surface portion 97 , the curved surface section 98 and the tapered surface portion 99 of the free piston 57 and the tapered surface portion 82 , the curved surface section 83 and the large diameter cylindrical surface portion 84 of the housing body 54 arranged, that is, between the outer annular projection 93 of the free piston 57 and the inner annular protrusion 80 of the housing body 54 . The O-ring is in its original condition 59 formed so that its cross section including a central axis has a circular shape and an inner diameter is smaller than the cylindrical surface portion with a small diameter 97 of the free piston 57 and so that an outer diameter is larger than the cylindrical large diameter surface portion 84 of the housing body 54 . That is, the O-ring 59 is in engagement with both the piston 57 as well as the housing body 54 fitted in a radial direction.

Also is the O-ring 58 between the cylindrical surface portion 67 , the curved surface section 68 and the flange surface portion 69 of the cover element 53 and the tapered surface portion 103 of the free piston 57 arranged. The O-ring is in its original state 58 formed so that its cross section including a central axis has a circular shape and the same inner diameter as the cylindrical surface portion 67 of the cover element 53 Has. Both o-rings 58 and 59 hold the free piston 57 in a neutral position with respect to the housing 55 and allow the free piston 57 axially towards the upper chamber 12th and the lower chamber 13th relative to the housing 55 to move. The free piston 57 , which is located in the neutral position, is axially from the case bottom portion 67 of the housing body 54 and the lid flange portion 63 of the cover element 53 separated to move in an axial direction and has a gap to the lid cylinder portion 62 in a radial direction.

In the free piston 57 is the O-ring 59 in contact with the small diameter cylindrical surface portion 97 , the curved surface section 98 and the tapered surface portion 99 . Among these are the curved surface portion 98 and the tapered surface portion 99 to the direction of movement of the free piston 57 inclined towards. It also says in the free piston 57 the O-ring 58 in contact with the tapered surface portion 103 pointing in the direction of the free piston 57 is inclined.

In the case 55 is the O-ring 59 in contact with the tapered surface portion 82 , the curved surface section 83 and the large diameter cylindrical surface portion 84 . Among these are the sloped surface portion 82 and the curved surface portion 83 towards the direction of movement of the free piston 57 inclined. It is also in the housing 55 the O-ring 58 in contact with the cylindrical surface portion 67 , the curved surface section 68 and the flange surface portion 69 .

Consequently, there are a free piston contact surface on which the cylindrical small diameter surface portion 97 , the curved surface section 98 and the inclined surface portion 99 of the free piston 57 in contact with the O-ring 59 stand, and a housing contact surface on which the cylindrical large-diameter surface portion 84 , the curved surface section 83 and the inclined surface portion 82 of the housing 55 in contact with the O-ring 59 stand, formed so that the shortest distance between the sections that are in contact with the O-ring 59 stand by the movement of the free piston 57 is changed and that the direction of a segment connecting the sections that form the shortest distance is changed. In other words, the shapes of the cylindrical surface portion are small in diameter 97 , the curved surface section 98 and the tapered surface portion 99 and the shapes of the large diameter cylindrical surface portion 84 , the curved surface section 83 and the tapered surface portion 82 set so that the direction of the segment that is the shortest distance between the sections where the o-ring 59 in contact with the contact surface of the free piston 57 and the housing contact surface of the housing 55 stands, is changed. In detail if the free piston 57 on the side of the axial upper chamber 12th in terms of the housing 55 is placed, represents the shortest distance between the sections where the O-ring 59 in contact with the free piston contact surface and the housing contact surface, there is a difference in radius between the large diameter cylindrical surface portion 84 and the small-diameter cylindrical surface portion 97 represents (there is a difference in radius between the outer and inner diameter of the O-ring 59 is greater than the difference in radius between the large diameter cylindrical surface portion 84 and the small-diameter cylindrical surface portion 97 , becomes the O-ring 59 deformed by compression due to the difference and the deformed portion, that is, the segment with the shortest distance has an inclined angle equal to zero (0)). On the other hand, when the free piston is 57 towards the axial lower chamber 13th relative to the housing 55 moves are the sections that make up the o-ring 59 contact, the curved surface portion 98 and the curved surface portion 83 , and the place where the o-ring 59 is deformed to a maximum degree, that is, the segment with the shortest distance, has an inclined angle different from zero (0).

The piston flange section 94 is at one end of the free piston 57 educated. The piston flange section 94 has the inclined surface portion 103 that is on an inner perimeter thereof is inclined, and the curved surface portion 98 and the tapered surface portion 99 inclined on an outer periphery thereof. The lid cylinder section 62 which is located in the piston cylinder section 91 of the free piston 57 extends, is on a portion of the cover element 53 of the housing 55 educated. The O-ring 58 is arranged to be in contact with the tapered surface portion 103 on the inner peripheral surface of the piston flange portion 94 and the lid cylinder portion 62 to stand. The O-ring 59 is arranged to be in contact with the cylindrical small diameter surface portion 97 , the curved surface section 98 and the tapered surface portion 99 to stand, all of which on the outer peripheral surface of the piston flange portion 94 are arranged and the inclined surface portion 82 , and the curved surface portion 83 and the large-diameter cylindrical surface portion 84 all of which are part of the inner peripheral surface of the housing 55 are.

The damping force varying mechanism 35 is made by inserting the O-ring 59 in the housing 54 up to a position of the curved surface section 83 by fitting the free piston 57 on the inside of the housing body 54 and the O-ring 59 by placing the O-ring 58 on the inclined surface portion 103 of the free piston 57 by fitting the cover element 53 in the case body 54 , while the lid cylinder section 62 on the inside of the O-ring 58 is introduced, and by swaging the housing body 54 assembled. Consequently, the damping force varying mechanism becomes 35 , which was pre-assembled in this way, by means of screws of the female thread 52 of the housing 55 on the male thread 50 of the fastening shaft portion 21 the piston rod 16 attached. At this time, the lid flange portion comes into play 63 of the housing 55 in contact with the valve regulating element 47a of the damping force generating mechanism 32a and the damping force generating mechanism 32a , the piston body 14th and the damping force generating mechanism 32b are between the stem step portion 48 the piston rod 16 and the lid flange portion 63 of the housing 55 held. That is, the damping force varying mechanism 35 also serves as a fastener that supports the damping force generating mechanism 32a , the piston body 14th and the damping force generating mechanism 32b on the piston rod 16 attached. The outer diameter of the damping force varying mechanism, that is, the outer diameter of the case body 54 , is set to be less than the inner diameter of the cylinder to a degree that does not act as flow conduction resistance 10 .

The piston rod 16 has a pipe hole 105 on that at the end of the main shaft section 20th on the side of the mounting shaft section 21 is formed in a radial direction. The mounting stem portion 21 has a pipe hole 106 which is shaped in an axial direction to communicate with the lead hole 105 to stand. As a result, the upper chamber is standing 12th in connection with the housing 55 of the damping force varying mechanism 35 by means of the line holes 105 and 106 . The upper chamber is in detail 12th in connection with a connecting chamber for the upper chamber 107 going through the housing 55 , the O-ring 58 and the free piston 57 is determined. There is also the lower chamber 13th in connection with the housing 55 via a connecting hole 87 that is in the case bottom section 76 of the housing 55 is trained. The lower chamber is in detail 13th in connection with a connecting chamber for the lower chamber 108 going through the housing 55 , the O-ring 59 and the free piston 57 is determined. Also is the O-ring 59 that is between the case body 54 and the free piston 57 is arranged, arranged to always be between the housing 55 and the free piston 57 to seal and block the connection between the connecting chamber for the upper chamber 107 and the connecting chamber for the lower chamber 108 anytime.

The pipe holes 105 and 106 and the connecting chamber for the upper chamber 107 provide a line (a second line) 110 represents what oil from the lower chamber 12th of the cylinder 10 due to the movement of the piston 11 towards the upper chamber 12th flows out. The connection hole 87 the connecting chamber for the lower chamber 108 provides a line (a second line) 111 from which oil from the lower chamber 13th of the cylinder 10 due to the movement of the piston 11 towards the lower chamber 13th flows out. Consequently, a flow conduit becomes part of the conduit 110 and a flow conduit that corresponds to the entirety of the conduit 111 corresponds, in the housing 55 educated. The free piston 57 is arranged to be in the housing 55 to be mobile and separates the lines 110 and 111 into an upstream side and a downstream side. The lines 30a and 30b and the line 110 are in the flask 11 formed comprising a portion of the piston rod 16 . This is where the two lines are from the free piston 57 divided and essentially create a flow there, although a flow of oil between the upper chamber 12th and the lower chamber 13th is replaced, does not occur, the oil of the upper chamber 12th into the connecting chamber for the upper chamber 107 flows while the free piston is moving 57 relative to the housing 55 moves and consequently the same amount of oil flows towards the lower chamber 13th vacuum.

During the extension stroke, during which the piston rod 16 moves toward an extension side, the oil flows from the upper chamber 12th towards the lower chamber 13th over the lines 30a . When a piston speed is within a very slow speed range, the oil flowing from the upper chamber will flow 12th into the lines 30a flows, essentially towards the lower chamber 13th via a constant opening that is different from that in the piston 11 trained line grooves 43a is set, and the butterfly valve 45a that is in contact with the seat section 41a device. At this time, a damping force having an opening characteristic is generated (ie, the damping force is approximately proportional to the square of the piston speed). When the piston speed increases to reach a low speed range, the oil from the upper chamber drives off 12th into the lines 30a essentially flows away with the disc valve 45a to open and flows between the disc valve 45a and the seat section 41a into the lower chamber 13th . As such, a damping force is generated with a valve characteristic (ie, the damping force is roughly proportional to the piston speed).

At the displacement stroke in which the piston rod 16 moves toward a displacement side, the oil flows from the lower chamber 13th to the upper chamber 12th over the lines 30b . When a piston speed is within a very slow speed range, the oil flowing from the lower chamber will flow 13th into the lines 30b flows, essentially to the upper chamber 12th via a constant orifice created by the conduit grooves (not shown) that are in the piston 11 are formed, is set and the disc valve 45 that is in contact with the seat section 41b device. At this time, a damping force with an opening characteristic is generated (ie, the damping force is approximately proportional to the square of the piston speed). When the piston speed increases to reach a low speed range, the oil from the lower chamber drives off 13th into the lines 30b essentially flows away with the disc valve 45b to open and flows between the disc valve 45b and the seat section 41b to the upper chamber 12th . Therefore, a damping force is generated with a valve characteristic (ie, the damping force is roughly proportional to the piston speed).

Here, a range in which a frequency when the piston speed is low, that is, a frequency in the very low speed range (for example, 0.05 m / s), is relatively high (for example, more than 7 Hz), for example, a vibration of the slight surface unevenness of a road surface. In this situation, it is preferred to lower the damping force. Further, even if the piston speed is similarly low, a region where the frequency is relatively low (for example, less than 2 Hz) unlike the above is vibration such as shaking caused by rolling a vehicle body is produced. In this situation, it is preferred to increase the damping force.

Accordingly, the aforementioned damping force generating mechanism varies 35 the damping force corresponding to the frequency even when the piston speed is low in the same way. That is, when the piston speed is low, if the frequency of the piston is reversed 11 becomes high, an upper chamber pressure becomes 12th during the extension stroke of the piston 11 large and consequently the oil is brought to it from the upper chamber 12th into the connecting chamber for the upper chamber 107 of the damping force varying mechanism 35 via the line holes 105 and 106 the piston rod 16 to flow. At the same time, oil is brought in from the connecting chamber for the lower chamber 108 of the damping force varying mechanism 35 into the lower chamber 13th via the connecting hole 87 that is the opening on the downstream side of the conduit 111 trains to flow. In the meantime the free piston moves 57 towards the axially lower chamber 13th against a pretensioning force of the O-ring 59 that is on the side of the axial lower chamber 13th is arranged. In this way, as well as the piston 57 towards the axially lower chamber 13th moves, the oil flows from the upper chamber 12th into the connecting chamber for the upper chamber 107 and a flow rate of the oil flowing from the upper chamber 12th into the lines 30a flows and then through the damping force generating mechanism 32a into the lower chamber 13th flows is reduced. As a result, the damping force is reduced.

On the following displacement stroke, there is a pressure in the lower chamber 13th becomes large, the oil is made to do so from the lower chamber 13th into the connecting chamber for the lower chamber 108 of the damping force varying mechanism 35 via the connecting hole 87 to flow that forms the opening on the downstream side of the pipe. At the same time, oil is brought in from the connecting chamber for the upper chamber 107 in the upper chamber 12th via the line holes 105 and 106 the piston rod 16 to flow. In the meantime the free piston moves 57 that extends in the direction of the axially lower chamber 13th until that point has moved in Direction of the axially upper chamber 12th against a pretensioning force of the O-ring 58 that is on the side of the axially upper side 12th is arranged. In this way, as well as the free piston 57 towards the axially upper chamber 12th moves, the oil flows from the lower chamber 13th into the connecting chamber for the lower chamber 108 and a flow rate of the oil flowing from the lower chamber 13th into the lines 30b flows and then through the damping force generating mechanism 32b in the upper chamber 12th flows is reduced. As a result, the damping force is reduced.

In the range in which the frequency of the piston 11 is high, a frequency of movement of the free piston becomes 57 also high in proportion to the high frequency. As a result, in each of the aforementioned extension strokes, the oil flows from the upper chamber 12th into the connecting chamber for the upper chamber 107 . With each displacement stroke, the oil flows from the lower chamber 13th into the connecting chamber for the lower chamber 108 . Thereby, as described above, the damping force is kept in a lowered state.

On the other hand, if the piston speed is low, if the frequency of the piston 11 becomes low, the frequency of movement of the free piston becomes 57 also reduced proportionally to the low frequency. Therefore, in every initial state of the extension stroke, the oil flows from the upper chamber 12th into the connecting chamber for the upper chamber 107 . The free piston then compresses 57 the O-ring 59 and is on the side of the axially lower chamber 13th stopped and the oil does not flow from the upper chamber 12th towards the connecting chamber for the upper chamber 107 . Hence the flow rate of the oil coming from the upper chamber 12th into the lines 30a flows and then through the damping force generating mechanism 32a flows into the lower chamber in an unreduced state and hence the damping force is increased.

Even on the following displacement stroke, in its original state, the oil flows from the lower chamber 13th towards the connecting chamber for the lower chamber 108 . The free piston then compresses 57 the O-ring 58 and is on the side of the axially upper chamber 12th stopped and the oil does not flow from the lower chamber 13th towards the connecting chamber for the upper chamber 108 . Hence the flow rate of the oil coming from the lower chamber 13th into the lines 30b flows and then through the damping force generating mechanism 32b in the upper chamber 12th flows in an unreduced state, and hence the damping force is increased.

Thus, in the present embodiment, as described above, components for applying a biasing force to the free piston 57 to move it back to its neutral position, the o-rings 58 and 59 made of a rubber material is used. At the neutral position of the free piston 57 becomes the O-ring 59 that between the free piston 57 and the case body 54 is disposed between the large diameter cylindrical surface portion 84 of the housing 55 and the small-diameter cylindrical surface portion 97 of the free piston 57 positioned.

For example, when the free piston is on the extension stroke 57 from its neutral position towards the axially lower chamber 13th relative to the housing 55 moved, the large diameter cylindrical surface portion roll 84 of the housing 55 and the small-diameter cylindrical surface portion 97 of the free piston 57 together the O-ring 59 , ie, rotate the O-ring 59 so that the inner diameter side and the outer diameter side of the O-ring 59 move in opposite directions and the axially lower chamber 13th relative to the housing 55 is moved. The curved surface section then rolls 83 and the tapered surface portion 82 of the housing 55 on the side of the axially upper chamber 12th and the curved surface portion 98 and the tapered surface portion 99 of the free piston 57 on the side of the axially lower chamber 13th the O-ring 59 and compress the O-ring at the same time 59 in the axial and radial directions of the free piston 57 . Then compress the curved surface section 83 and the tapered surface portion 82 of the housing 55 on the side of the axially lower chamber 13th and the curved surface portion 98 and the tapered surface portion 99 of the free piston 57 on the side of the axially upper chamber 12th the O-ring 59 in the axial and radial directions of the free piston 57 .

At this point there is an area where the O-ring 59 between the large diameter cylindrical surface portion 84 of the housing 55 and the cylindrical surface portion 97 with a small diameter of the free piston 57 is rolled, and an area where the O-ring 59 between the curved surface portion 83 and the tapered surface portion 82 of the housing 55 and the curved surface portion 98 and the tapered surface portion 99 of the free piston 57 is rolled, a rolling area in which the O-ring 59 is rolled at a position that is from a downstream side end within a moving range of the free piston 57 is separated. Further, at the position separated from the downstream side end, a rolling area is a moving area in which the O-ring 59 in a direction of movement of the free piston 57 moved in the state in which the O-ring 59 in contact with both the housing 55 as well as the free piston 57 stands. The term "move" defines that at least one downstream end position (a lower end position in 2 ) of the O-ring 59 is changed in the direction of movement of the free piston.

There is also an area where the O-ring 59 between the curved surface portion 83 and the tapered surface portion 82 of the housing 55 and the curved surface portion 98 and the tapered surface portion 99 of the free piston 57 is compressed, a movement direction deformation area in which the O-ring 59 an elastic deformation in the direction of movement of the free piston 57 at the downstream end within the range of motion of the free piston 57 learns. The term "elastic deformation in the movement direction deformation range" specifies a deformation when an upstream end position (an upper end position in 2 ) of the O-ring 59 is changed in the direction of movement of the free piston, but a downstream end position is not changed. In the present embodiment, the rolling area and the moving area partially overlap in the moving direction deformation area.

At the following displacement stroke when the free piston 57 towards the axially upper chamber 12th relative to the housing 55 moves, solve the curved surface portion 83 and the tapered surface portion 82 of the housing 55 on the side in the axially lower chamber 13th and the curved surface portion 98 and the tapered surface portion 99 of the free piston 57 on the side of the axially upper chamber 12th the compression of the O-ring 59 . The curved surface section then rolls 83 and the tapered surface portion 82 of the housing 55 on the side of the axially upper chamber 12th and the curved surface portion 98 and the tapered surface portion 99 of the free piston 57 on the side of the axially lower chamber 13th the O-ring 59 and at the same time release the compression of the O-ring 59 . Then roll the cylindrical surface portion with a large diameter 84 of the housing 55 and the small-diameter cylindrical surface portion 97 of the free piston 57 together the O-ring 59 and move the O-ring at the same time 59 towards the axially upper chamber 12th relative to the housing 55 . Hence, in the state in which the O-ring 58 on the cylindrical surface portion 67 , the curved surface section 68 and the flange surface portion 69 of the housing 55 is held, the free piston compresses 57 the O-ring 58 between the cover element 53 and the free piston 57 in the axial and radial directions of the free piston 57 in the vicinity of its neutral position by means of the cylindrical surface portion 67 , the curved surface section 68 and the flange surface portion 69 and the tapered surface portion 103 of the free piston 57 .

On the following extension stroke, the cylindrical surface section loosen 67 , the curved surface section 68 and the flange surface portion 69 of the housing 55 and the tapered surface portion 103 of the free piston 57 the compression of the O-ring 58 by relative movement in a separation direction. The large diameter cylindrical surface portion 84 of the housing 55 and the small-diameter cylindrical surface portion 97 of the free piston 57 roll the O-ring together 59 and move the O-ring at the same time 59 towards the axially lower chamber 13th relative to the housing 55 . When the free piston 57 passes through its neutral position, it operates the O-ring 59 in the same way as described above.

With this setup, the O-ring 58 deformed in the moving direction in the moving direction deformation area by pressure and the other O-ring 59 moves in the direction of movement of the free piston 57 in the direction of movement.

The characteristic curve of a load over the displacement of the free piston 57 that of the O-rings 58 and 59 formed from a rubber material has a non-linear characteristic as shown in FIG 3 shown on. In other words, the load characteristic approximates a linear characteristic within a predetermined range in front of and behind the neutral position of the free piston 57 . Outside the predetermined range, a rate of increase in the load increases slowly depending on the offset. As described above, as the amplitude of the piston 11 also in the range in which the operating frequency of the piston 11 is high, is low, the displacement of the free piston becomes 57 also low and the free piston 57 is operated within the linear characteristic range in front of and behind its neutral position. This is the free piston 57 easy to move, moves according to the resonance due to the vibration of the piston 11 and helps reduce the damping force generated by the damping force generating mechanism 32a and 32b is generated at.

On the other hand, because the amplitude of the piston 11 in the range in which the operating frequency of the piston 11 is small, becomes large, the displacement of the free piston becomes 57 big and the free piston 57 is within the non-linear characteristic range, as in 3 shown operated. This will gradually make the free piston difficult 57 to move smoothly and he has difficulty in reducing the damping force generated by the damping force generating mechanism 32a and 32b is generated on.

In the shock absorber disclosed in Japanese Unexamined Utility Model Application First Publication No. H07-019643, a movement of a spool dividing the inside of a housing into two chambers is regulated by means of an elastic body (which corresponds only to the movement direction deformation range of the first embodiment) and a damping force is smoothly changed. However, since resistance to movement of the spacer ring increases greatly, there is a need to improve this characteristic (when rubber is compressed in an axial direction, a spring constant increases greatly).

In contrast, according to the first embodiment described above, are under the cylindrical surface portion with a small diameter 97 , the curved surface section 98 and the tapered surface portion 99 of the free piston 57 that are in contact with the O-ring 59 stand, the curved surface section 98 and the tapered surface portion 99 in the direction of movement of the free piston 57 inclined. Under the sloped surface section 82 , the curved surface section 83 and the large diameter cylindrical surface portion 84 of the housing 55 that are in contact with the O-ring 59 are the inclined surface section 82 and the curved surface portion 83 in the direction of movement of the free piston 57 inclined. Due to the movement of the free piston 57 becomes the shortest distance between the free piston contact surface of the small-diameter cylindrical surface portion 97 , the curved surface section 98 and the tapered surface portion 99 that is in contact with the O-ring 59 stands, and the housing contact surface of the tapered surface portion 82 , the curved surface section 83 and the large-diameter cylindrical surface portion 84 that is in contact with the O-ring 59 stands, changed. Therefore, when the damping force is changed depending on the frequency, it is possible to smoothly change the damping force. For example, in the shock absorber of the first embodiment, when the speed of the piston 11 0.05 m / s and if the operating frequencies of the piston are 0.50 Hz, 0.80 Hz, 1.59 Hz, 1.99 Hz, 3.18 Hz, 3.98 Hz, 4.97 Hz, 6, 12 Hz, 7.96 Hz, 9.95 Hz, 15.92 Hz and 19.89 Hz are sequentially from the outside, the relationship between a piston stroke and a damping force becomes in 4th shown. It's over 4th it can be seen that the damping force is changed very evenly at each frequency. It can also be seen that it is possible to change the damping force with a low frequency in the vicinity of 0, where a stroke of the piston 11 is low, for example at 0.05 Hz, and to reduce the damping force at a relatively high frequency of for example 4.97 Hz or more. Meanwhile, at least one of the small-diameter cylindrical surface portion may 97 , the curved surface section 98 and the tapered surface portion 99 and the large diameter cylindrical surface portion 84 , the curved surface section 83 and the tapered surface portion 82 be formed so that their shapes change the shortest distance between the distance of the free piston contact surface which is in contact with the elastic body and the portion of the housing contact surface which is in contact with the elastic body.

The sloped, sloped surface portion 99 and the curved surface portion 98 of the free piston 57 include the curved surface portion 98 . The sloped, sloped surface portion 82 and the curved surface portion 83 of the housing 55 include the curved surface portion 83 . It is therefore possible to change the damping force more smoothly. Further, even in this case, at least one of the curved surface portions may 83 and 98 be provided.

Because the radii of curvature of the curved surface sections 83 and 98 are larger than the cross-sectional radius of the O-ring 59 , it is possible to change the damping force more smoothly.

The sloped surface section 99 and the curved surface portion 98 of the free piston 57 and the tapered surface portion 82 and the curved surface portion 83 of the housing 55 lie in the direction of movement of the free piston 57 across from. It is therefore possible to use the O-ring 59 to compress adequately.

Because the O-ring 58 that undergoes pressure deformation when the free piston moves 57 moved in one direction and the O-ring 59 that undergoes pressure deformation when the free piston moves 57 moved in the other direction, it is possible to smoothly change the damping force in both the extension stroke and the displacement stroke. Therefore, since the damping force is changed smoothly even in the case of a frequency change, a change in the piston speed, etc., no discomfort in driving is caused by the change in the damping force. In particular, in the case of a change in posture, the damping force gradually increases, and it is possible to suppress the change in posture without causing discomfort to a driver. Therefore, it is possible to provide a higher level vehicle in ride comfort and controllability as compared with the shock absorber disclosed in the unexamined Japanese Utility model registration with the first publication no. H07-019642 is disclosed.

In the present embodiment, the piston flange portion is 94 at one end of the free piston 57 educated. The piston flange section 94 includes the tapered surface portion 103 inclined on the inner periphery thereof and the curved surface portion 98 and the tapered surface portion 99 inclined on the outer periphery thereof. The lid cylinder section 62 which is located in the piston cylinder section 91 of the free piston 57 extends is on a portion of the housing 55 arranged. The O-ring 58 is arranged to be in contact with the tapered surface portion 103 of the inner circumference of the piston flange portion 94 and the lid cylinder portion 62 to guess. The O-ring 59 is arranged to be in contact with the curved surface portion and the inclined surface portion 99 the outer periphery of the piston flange portion 94 and the inner peripheral surface of the housing 55 to guess. Until then the O-ring is 59 in the case body 54 arranged and the free piston 57 is in the case 54 and the O-ring 59 arranged. The O-ring 58 is on the free piston 57 arranged. The lid cylinder section 62 is in the O-ring 58 introduced. In the meantime, the cover element 53 on the case body 54 attached. This will assemble the shock absorber. Accordingly, the assembling efficiency of each component can be improved.

The O-ring 59 that is between the case body 54 and the free piston 57 is arranged, acts as a spring, which has a biasing force in the opposite direction when the free piston 57 is offset, generated and seals between the housing body 54 and the free piston 57 from. Therefore the O-ring is used 59 as a seal that always keeps the connection between the connecting chamber for the upper chamber 107 and the connecting chamber for the lower chamber 108 blocks and can reduce the number of components.

Because the O-ring 59 between the free piston 57 and the case 55 is rolled, it is possible to change the damping force more evenly. In addition, even when an O-ring having a small cross-sectional diameter is used, the O-ring is rolled, and hence a stroke displacement of the free piston to which resistance is applied by means of the O-ring is allowed to increase (to be larger than the diameter of the O-ring). Thus, the technology disclosed in Japanese Unexamined Utility Model Application First Publication No. H07-019642 is disclosed in which rubber is only compressed (a stroke displacement cannot be used exceeding a thickness of the rubber in a compression deformation direction) and the technology of the present embodiment is identical in that both use rubber. Further, as described above, both are different in view of the use of the rubber and therefore both are completely different in view of the technical thought thereof.

The free piston 57 points in the movement direction deformation area in which the O-ring 59 in the direction of movement of the free piston 57 is elastically deformed at the downstream side end within the moving range of the free piston 57 on. Furthermore, the free piston 57 a rolling area in which the O-ring 59 at a position separated from the downstream side end. It is therefore possible to change the damping force more smoothly.

The rolling area is partially overlapped by the moving direction deformation area. For this reason, the resistance caused by the rolling is gradually changed to the resistance caused by the pressure deformation in the direction of movement. It is therefore possible to change the damping force more smoothly. In particular, it is possible to prevent the spring constant from increasing sharply and to obtain an approximately linear characteristic.

In the present embodiment, the shape of the free piston contact surface becomes the small-diameter cylindrical surface portion 97 , the curved surface section 98 and the tapered surface portion 99 that is in contact with the O-ring 59 stands, and the shape of the housing contact surface of the large-diameter cylindrical surface portion 84 , the curved surface section 83 and the tapered surface portion 82 that is in contact with the O-ring 59 is set so that the direction of the segment connection of the shortest distance between the free piston contact surface and the housing contact surface is changed. Therefore, even if the direction of the force generated by the O-ring is changed, it is possible to change the damping force more smoothly because the resistance in the moving direction of the free piston is changed.

The free piston 57 has the moving direction deformation area in which the O-ring is elastic in the moving direction of the free piston 57 is deformed at the downstream side end within the moving direction of the free piston 57 on. Furthermore, the free piston 57 a range of motion in which the O-ring 59 in the direction of movement of the free piston 57 moved in the state in which the O-ring 59 in contact with both the housing 55 as well as the free piston 57 stands at the position separated from the downstream side end. Therefore, the stroke of the free piston in which resistance is applied from the O-ring is allowed to increase, for example, to be larger than the diameter of the O-ring, and it is possible to adjust the damping force more evenly.

Further, since the moving range is partially overlapped in the moving direction deformation range, it is possible to set the damping force more uniformly.

A variety of O-rings are provided. The O-ring 58 is deformed by compression in the moving direction in the moving direction deformation area. The O-ring 59 moves in the direction of movement of the free piston 57 in the direction of movement. It is therefore possible to adjust the damping force uniformly depending on the direction of movement of the free piston 57 adjust.

Since the line 110 in the flask 11 is arranged, it is possible to simplify the structure.

Because the connection hole 87 as an opening upstream and downstream of the conduit 111 is provided, the resistance to the movement of the free piston also acts on the opening in addition to the O-ring, and it is therefore possible to adjust the damping force more evenly. Furthermore, in the aforementioned embodiment, there is a small opening in the free piston 57 provided and it is therefore possible to change the characteristics. In addition, the aforementioned embodiment has shown that the housing 55 from the cover element 53 and the case body 54 is trained.

However, if the O-ring 58 is designed to be in contact with the outer periphery of the lower end of the piston rod 16 by shortening the lid cylinder section 62 To stand, a portion of the lower end of the piston rod also represents the housing 55 represent.

[Second embodiment]

Next, a second embodiment will focus on portions different from those of the first embodiment based mainly on 5 described. Furthermore, the same names and reference numerals are used for parts that are common to the first embodiment.

In the second embodiment, a damping force varying mechanism is different 35 partially different from that of the first embodiment. In detail is compared with the case body 54 of the first embodiment, a case body 54 of the damping force varying mechanism 34 without a case bottom section 76 and a portion of a housing cylinder portion 75 on the side of the case bottom section 76 educated. Therefore, there is in the damping force varying mechanism 35 of the second embodiment of the housing body 54 formed so that the housing cylinder portion 75 and its inner annular projection 80 are shorter in their axial length than that of the first embodiment without the communication hole 87 and the connecting chamber for the lower chamber 108 the first embodiment.

The damping force varying mechanism 35 The second embodiment is designed so that a free piston 57 on the side of the piston crown section 92 that is outward via the housing 55 in an axial direction in a state that the free piston 57 in a neutral position by means of the O-rings 58 and 59 is arranged ( 5 shows a natural state) protrudes, is arranged. The O-ring 59 always blocks the connection between a connecting chamber for the upper chamber 107 and a lower chamber 13th .

The damping force varying mechanism 35 The second embodiment is designed so that when a piston speed is low, if the operating frequency of a piston 11 becomes large, the pressure of an upper chamber 12th becomes large at the extension stroke. As such, an oil is obtained from the upper chamber 12th into the connecting chamber for the upper chamber 107 of the damping force varying mechanism 35 via line holes 105 and 106 a piston rod 16 flows. In the meantime the free piston moves 57 towards the lower chamber 13th against a pretensioning force of the O-ring 59 on the side of the axially lower chamber 13th . In this way, as well as the free piston 57 towards the lower chamber 13th moves, oil flows from the upper chamber 12th into the connecting chamber for the upper chamber 107 and a flow rate of the oil flowing from the upper chamber 12th in lines 30a flows and then through the damping force generating mechanism 32a into the lower chamber 13th flows is reduced. Therefore, oil easily flows into the damping force generating mechanism 32a and consequently the damping force is lowered.

On the following displacement stroke, there is a pressure in the lower chamber 13th becomes large, oil is brought in from the connecting chamber for the upper chamber 107 in the upper chamber 12th via line holes 105 and 106 the piston rod 16 to flow. In the meantime the free piston moves 57 facing towards the upper chamber 13th until that time has moved towards the upper chamber 12th against a pretensioning force of the O-ring 58 on the side of the upper chamber 12th . In this way, the free piston rises as well as itself 57 moved towards the upper chamber, an apparent volume of the lower chamber 13th on and a flow rate of the oil coming from the lower chamber 13th into the lines 30d flows and then through the damping force generating mechanism 32b in the upper chamber 12th flows is reduced. Therefore, the oil easily flows into the damping force generating mechanism 32b and consequently the damping force is lowered.

In the damping force generating mechanism 35 The second embodiment is the operation of the O-rings 58 and 59 when the free piston is relative to the housing 55 moved, the same as in the first embodiment.

According to the second embodiment, as described above, it is possible to adjust the axial length of the damping force varying mechanism 35 and the weight of the damping force varying mechanism is also reduced.

[Third embodiment]

Next, a third embodiment will be described focusing on portions different from those of the first embodiment based mainly on 6A and 6B . Furthermore, the same names and reference numerals are used for parts that are common to the first embodiment.

In the third embodiment, a damping force varying mechanism is different 35 partially different from that of the first embodiment. That is, a cover element 35 which is partially different from that of the first embodiment is used. This cover element 35 is with a cylinder section (a housing-side annular projection) 121 on an outer peripheral side of the lid flange portion 63 Mistake. A tip surface section 122 (tip face part) of the cylinder section 121 , the cover flange section 63 opposite is along a direction perpendicular to the axis of the lid member 53 is provided.

In the third embodiment, a case body 54 which is partially different from that of the first embodiment is used. First, the structure of a housing cylinder section differs 75 on the side of a case bottom section 76 . The inner peripheral surface of an inner, annular protrusion 80 of the housing cylinder section 75 is as a curved surface section (an inclined surface) 125 between a cylindrical surface portion of small diameter 81 and a curved surface portion 83 educated. This curved surface section 125 is formed in an annular shape so that its diameter with the distance to the cylindrical surface portion of small diameter 81 rises and is formed so that a cross section comprising the central axis of a housing body 54 has an arcuate shape.

Furthermore, the housing body 54 formed so that the housing bottom portion 76 differs from that of the first embodiment. The case bottom section 76 is with a concave section 128 at the center thereof, which is toward the lid member 53 with respect to a floor section body 127 on the side of the inner circumference is excluded. The concave section 128 is formed in a capped hexagonal cylindrical shape with a cross section perpendicular to the axis of the case body 54 has a hexagonal shape. When the damping force varying mechanism 35 on the piston rod 16 is screwed, a hexagonal wrench is inserted into the concave section 128 fitted. The case bottom section 76 is with a connecting hole 87 in the center of a lid portion of the concave portion 128 Mistake.

Furthermore, the housing body 54 designed to be formed primarily by spinning. Therefore, the case body 54 a curved surface section 125 between a cylindrical surface portion of small diameter 81 and a curved surface portion 83 on.

In the third embodiment, the free piston 57 which is partially different from that of the first embodiment is used. The free piston 57 the third embodiment has a shape in which a piston cylinder portion 91 further from a piston crown section 92 extends in an axial direction.

The piston cylinder section 91 is provided with an outer annular protrusion (a piston-side annular protrusion 93 provided with an annular shape extending outward in a radial direction on an outer circumference thereof at an axially central position thereof. A curved surface section 98 , a sloped surface section 99 and a large diameter cylinder surface portion 100 are in turn on an outer peripheral surface of the outer annular protrusion 93 formed starting at the side of a lower chamber. Further, an inclined surface portion (an inclined surface) 131 and a curved surface portion (an inclined surface) 132 on the cylindrical surface portion with large diameter 100 educated. The sloped surface section 131 , the one with the large-diameter cylindrical surface portion 100 is formed so that its diameter is spaced apart from the large-diameter cylindrical surface portion 100 decreases. The curved surface section 132 , the one with the beveled surface section 131 is formed in an annular shape so that its diameter with the distance to the tapered surface portion 131 increases. A cylindrical surface section with a small diameter 133 is with the curved surface portion 132 connected. The small diameter cylindrical surface portion 133 has the same diameter as the large diameter cylindrical surface portion 97 on. The curved surface section 132 is designed so that its cross section includes a central axis of the free piston 57 has an arcuate shape. The curved surface sections 98 and 132 , the beveled surface sections 99 and 131 and the large-diameter cylindrical surface portion 100 are on the outer annular protrusion 93 educated. The outer annular protrusion 93 the third embodiment is symmetrical with respect to a plane passing through the axially central position thereof.

The free piston 57 is slidable in a large diameter cylindrical surface section 84 of the housing body 54 on the large diameter cylindrical surface portion 100 , a cylindrical surface portion with a small diameter 91 of the housing body 54 on the small-diameter cylindrical surface portion 97 and a cylinder section 121 of the cover element 53 on the small-diameter cylindrical surface portion 133 fitted. In this state are a position of the curved surface portion 125 of the housing body 54 and a position of the curved surface portion 98 of the free piston 57 superimposed therefrom in radial directions. That is, the curved surface section 83 and the curved surface portion 125 of the housing body 54 and the curved surface portion 98 and the tapered surface portion 99 of the free piston 57 each other in a direction of movement of the free piston 57 opposite. Further, are a position of the tip surface portion 122 of the cylinder section 121 of the cover element 53 and a position of the tapered surface portion 131 and the curved surface portion 132 of the free piston 57 superimposed on each other in radial directions thereof. That is, the tip surface portion 122 of the cylinder section 121 and the tapered surface portion 131 of the curved surface section 132 of the free piston 57 are opposite to each other in the direction of movement of the free piston.

Hence is an O-ring 59 ( 6th shows a natural state) between the inclined surface portion 99 , the curved surface section 98 and the small-diameter cylindrical surface portion 97 of the free piston 57 and the curved surface portion 125 , the curved surface section 83 and the large diameter cylindrical surface portion 84 of the housing body 54 as in the first embodiment.

In the third embodiment is an O-ring 58 ( 6th shows a natural state) between the large-diameter cylindrical surface portion 84 of the housing body 54 , the tip surface section 122 of the cover element 53 and the tapered surface portion 131 , the curved surface section 132 and the large diameter cylindrical surface portion 133 of the free piston 57 arranged. When the O-ring 58 also in the natural state like the O-ring 59 is located, its inner diameter is smaller than an outer diameter of the cylindrical surface portion with a small diameter 133 of the free piston 57 and its outer diameter is larger than its inner diameter of the large-diameter cylindrical surface portion 84 of the housing body 54 . That is, the O-ring 58 will also engage both the free piston 57 as well as the housing body 54 fitted in a radial direction.

Both of the o-rings 58 and 59 are the same size. Both of the o-rings 58 and 59 hold the free piston 57 within a predetermined neutral range with respect to the housing 55 and allow the free piston 57 axially in both the axial upper and lower chambers 12th and 13th relative to the housing 55 to move.

Accordingly, stands for the free piston 57 the third embodiment of the O-ring 58 in contact with the small diameter cylindrical surface portion 133 , the curved surface section 132 and the tapered surface portion 131 . The curved surface section 132 and the tapered surface portion 131 are in the direction of movement of the free piston 57 inclined. It is also in the housing 55 the O-ring 58 in contact with the large diameter cylindrical surface portion 84 and the tip face portion 122 .

In other words, it is the outer annular protrusion 93 on the outer periphery of the free piston 57 intended. Axially opposed surfaces of the outer annular projection 33 form the curved surface section 98 and the tapered surface portion 99 or the curved surface section 132 and the tapered surface portion 131 out. The inner annular protrusion 80 and the cylinder section 121 are on opposite sides of the outer annular protrusion 93 the inner circumference of the housing 55 intended. The inner annular protrusion 80 forms the curved surface section 125 and the curved surface portion 83 out. The cylinder section 121 extends inwardly from the housing 55 in an annular shape and forms the tip surface portion 122 out. The O-ring 59 and the O-ring 58 are between the outer annular projection 93 and the inner annular protrusion 80 or between the outer annular projection 93 and the cylinder section 121 arranged.

The damping force varying mechanism 35 the third embodiment is by inserting the O-ring 59 in the case body 54 up to a position of the curved surface 83 by fitting the free piston 57 into the interior of the housing body 54 and the O-ring 59 by fitting the O-ring 58 between the free piston 57 and the case body 54 under application of force, by fitting the cylinder section 121 between the free piston 57 and the case body 54 and by fixing the cover element 53 on the case body 54 assembled.

The O-ring 58 that is between the case body 54 and the free body 57 is arranged is arranged around between the housing 55 and the free piston 57 to seal and always blocks the connection between the connecting chamber for the upper chamber 107 and a connecting chamber for the lower chamber 108 .

In the damping force varying mechanism 35 of the third embodiment are O-rings 58 and 59 that is between the case body 54 and the free piston 57 are arranged between the large-diameter cylindrical surface portion 84 of the housing body 54 and the small diameter cylindrical surface portion 97 of the free piston 57 and between the large diameter cylindrical surface portion 84 of the housing body 54 and the small-diameter cylindrical surface portion 133 of the free piston 57 in a neutral position of the free piston 57 arranged.

For example, during the extension stroke, when the free piston is 57 from its neutral position towards the lower chamber 13th relative to the housing 55 moved, the large diameter cylindrical surface portion roll 84 of Housing 55 and the small-diameter cylindrical surface portion 97 of the free piston 57 together the O-ring 59 and move the O-ring 59 towards the lower chamber 13th relative to the housing 55 as in the first embodiment. The curved surface section then rolls 83 and the curved surface portion 125 of the housing 55 on the side of the axial upper chamber 12th and the curved surface portion 98 and the tapered surface portion 99 of the free piston 57 on the side of the axial lower chamber 13th the O-ring 59 and compress the O-ring 59 simultaneously in the axial and radial directions of the free piston 57 . Then compress the curved surface section 83 and the curved surface portion 125 of the housing 55 on the side of the lower chamber 13th and the curved surface portion 98 and the tapered surface portion 99 of the free piston 57 on the side of the upper chamber 12th the O-ring 59 in the axial and radial directions of the free piston 57 . In the meantime, in the second embodiment, on the extension stroke when the free piston 57 move from its neutral position towards the lower chamber 13th relative to the housing 55 moved, the large diameter cylindrical surface portion roll 84 of the housing 55 and the small-diameter cylindrical surface portion 133 of the free piston 57 together the O-ring 58 and move the O-ring 58 towards the lower chamber 13th relative to the housing 55 .

At the following displacement stroke when the free piston 57 towards the axially upper chamber 12th relative to the housing 55 moves, solve the curved surface portion 83 and the curved surface portion 125 of the housing 55 on the side of the lower chamber 13th and the curved surface portion 98 and the tapered surface portion 99 of the free piston 57 on the side of the upper chamber 12th the compression of the O-ring 59 as in the first embodiment. The curved surface section then rolls 83 and the curved surface portion 125 of the housing 55 on the side of the upper chamber and the curved surface portion 98 and the tapered surface portion 99 of the free piston 57 on the side of the lower chamber 13th the O-ring 59 and release the compression of the O-ring at the same time 59 further. Further, the large diameter cylindrical surface portion rolls 84 of the housing 55 and the small-diameter cylindrical surface portion 97 of the free piston 57 together the O-ring 59 and move the O-ring at the same time 59 towards the upper chamber 12th relative to the housing 55 . Meanwhile, in the second embodiment, on the displacement stroke when the free piston 57 towards the upper chamber 12th relative to the housing 55 moved, the large diameter cylindrical surface portion roll 84 of the housing 55 and the small-diameter cylindrical surface portion 133 of the free piston 57 together the O-ring 58 and move the O-ring 58 relative to the housing 55 towards the upper chamber 12th . The free piston then compresses 57 the O-ring 58 in the axial and radial directions of the free piston 57 by means of the large diameter cylindrical surface portion 84 and the tip surface portion 122 of the housing 55 and the tapered surface portion 131 and the curved surface portion 132 of the free piston 57 .

At this point there will be an area where the O-ring 58 between the large diameter cylindrical surface portion 84 of the housing 55 and the small-diameter cylindrical surface portion 133 of the free piston 57 is rolled, a rolling area in which the O-ring 58 is rolled at a position that is from a downstream side end within a moving direction of the free piston 57 is separated. Further, at the position separated from the downstream side end, the moving range is a moving range in which the O-ring 58 in a direction of movement of the free piston 57 moved to a state in which the O-ring is in contact with both the housing 55 as well as the free piston 57 stands. The term “moving” defines that at least one downstream end position (a lower end position in 6th ) of the O-ring 58 changed in the direction of movement of the free piston.

An area where the o-ring 58 between the tip surface portion 122 of the housing 55 and the curved surface portion 132 and the tapered surface portion 131 of the free piston 57 is compressed is a moving direction deformation area where the O-ring 58 an elastic deformation in the direction of movement of the free piston 57 at the downstream end within the direction of movement of the free piston 57 learns. The term “elastic deformation in the moving direction deformation range” is defined as a deformation when an upstream end position (a lower end position in 6th ) of the O-ring 58 is changed in the direction of movement of the free piston, but a downstream end position is not changed. In this embodiment, the roller area and the moving area partially overlap in the moving direction deformation area.

On the extension stroke that follows the foregoing, the tip surface portion loosens 122 of the housing 55 and the tapered surface portion 131 and the curved surface portion 132 of the free piston 57 the compression of the O-ring 58 . The large diameter cylindrical surface portion 84 of the housing 55 and the small-diameter cylindrical surface portion 133 of the free piston 57 roll the O-ring together 58 and move the O-ring 58 towards the axially lower chamber 13th relative to the housing 55 . Even in the case where the O-ring 59 , the large diameter cylindrical surface portion 48 of the housing 55 and the small-diameter cylindrical surface portion 97 of the free piston 57 together the O-ring 59 roll and the O-ring 59 towards the axially lower chamber 13th move relative to the housing. Hence when the free piston 57 passes through its neutral position, it operates the O-rings 58 and 59 in the same way as described above.

According to the third embodiment described above, axially opposed surfaces form the outer annular projection 93 attached to the outer periphery of the free piston 57 are formed, the curved surface portion 98 and the tapered surface portion 99 or the inclined surface section 131 and the curved surface portion 132 out. The inner annular protrusion 80 showing the curved surface sections 83 and 125 and the cylinder portion 121 , which is the tip surface section 122 are on opposite sides of the outer annular projection 93 the inner circumference of the housing 55 intended. The O-ring 58 and the O-ring 59 are between the annular outer protrusion 93 and the cylinder section 121 or between the outer annular projection 93 and the inner annular protrusion 80 intended. It is therefore possible to use the O-rings 58 and 59 to unify.

Because the concave section 128 into which a hexagonal key is fitted in the housing 55 of the damping force varying mechanism 35 is provided, the workability becomes when the damping force varying mechanism 35 in the piston rod 16 is screwed, improved.

Furthermore, in the third embodiment, a coil spring can be placed between the cover flange portion 63 of the cover element 53 and the piston crown section 92 of the free piston 57 be arranged and a further spiral spring can be arranged between the bottom section body 127 of the housing body 54 and the piston crown section 92 of the free piston 57 be arranged, whereby the free piston 57 is held in its neutral position. With this structure, even if the stroke of the free piston 57 increases, it's simply the free piston 57 in its neutral position. In addition, the spiral spring (s) can be provided in the other embodiments.

Furthermore, as in 7A shown, only the beveled surface sections can 99 and 131 at the axially opposite sides of the outer annular projection 93 of the free piston 57 be provided or only the inclined surface section 82 may be between the small diameter cylindrical surface portions 81 and the large-diameter cylindrical surface portions 84 of the inner annular protrusion 80 of the housing body 54 (in 7A are the O-rings 58 and 59 in a natural state).

Furthermore, as in 7B shown in the natural state angled rings 135 and 136 (in 7B shown in the natural state) whose cross-sections including a central axis have a quadrilateral shape, instead of the O-rings 58 and 59 be provided. Even in this case the angled rings are 135 and 136 configured to engage the free piston 57 and the case 55 to be effected in a radial direction.

Additionally, as in 7C shown can be a sealing ring 137 on the free piston 57 be melted and adhered. With this structure, the number of parts is reduced and it is easy to handle the parts. In the meantime, even if the sealing ring 137 on the housing 55 adheres, the same effect can be obtained. This can also be done with the O-rings 58 and 59 of the first embodiment can be applied.

[Fourth embodiment]

Next, a fourth embodiment will be described, focusing on portions different from those of the first and third embodiments based mainly on 8th . Furthermore, the same names and reference numerals are used for parts that are identical to the first and third embodiment.

In the fourth embodiment, a damping force varying mechanism is different 35 also partially different from that of the first and third embodiments. That is, in the damping force varying mechanism 35 of the fourth embodiment become a lid member 53 and a free piston 57 which are identical to those of the third embodiment are used. In the damping force varying mechanism 35 a case body differs from the fourth embodiment 54 partially different from that of the first embodiment.

In the case of the housing body 54 becomes a case bottom section 76 with an extending shaft portion 141 provided in the center thereof, which is opposed in an axial direction to a housing cylinder portion 75 extends. The case bottom section 76 and the extending shaft portion 141 are with a connecting hole 87 provided in the center thereof, which runs through it in an axial direction. On the side of the case bottom section 76 of the extending shaft portion 141 is a socket section 142 provided which has a large diameter. The extending shaft portion 141 is made up of a fastening shaft section 143 formed, which is a portion that the base portion 142 does not include and a smaller diameter than the base portion 142 having. A male thread 144 is on the opposite side of the mounting stem portion 143 to the base section 142 educated.

The free piston 57 which is identical to that of the third embodiment is in the case body 54 arranged.

An o-ring 59 ( 8th shows a natural state) is between the tapered surface portion 99 , the curved surface section 98 and the small-diameter cylindrical surface portion 97 of the free piston 57 and the tapered surface portion 82 , the curved surface section 83 and the large diameter cylindrical surface portion 84 of the housing body 54 as in the third embodiment.

An o-ring 58 ( 8th shows a natural state) is between the large-diameter cylindrical surface portion 84 of the housing body 54 , the tip surface section 122 of the cylinder section 121 of the cover element 53 and the tapered surface portion 131 , the curved surface section 132 and the small-diameter cylindrical surface portion 133 of the free piston 57 as in the third embodiment.

In the fifth embodiment, the attachment shaft portion is 21 the piston rod 16 designed to have a short axial length. The damping force varying mechanism 35 gets into a male thread 50 of the fastening shaft portion 21 screwed to be in contact with a shank step portion 48 to get. That is, a piston body 14th is not on the piston rod 16 attached. Consequently, are a damping force generating mechanism 32b , the piston body 14th and a damping force generating mechanism 32a on the attachment shaft portion 143 of the damping force varying mechanism 35 by means of a mother 145 attached. That is, in the state where a valve regulating element 47b of the damping force generating mechanism 32b in contact with the base portion 142 device and if a valve regulating element 47a of the damping force generating mechanism 32a in contact with the mother 145 device will be the damping force generating mechanism 32b , the piston body 14th and the damping force generating mechanism 32a between the base section 142 and the mother 145 held.

In the damping force varying mechanism 35 the fourth embodiment when the free piston 57 relative to the housing 55 moves is the operation of the O-rings 58 and 59 the same as that in the third embodiment.

[Fifth embodiment]

Next, a fifth embodiment will focus on portions different from those of the first embodiment based primarily on 9 described. Furthermore, the same names and reference numerals are used for parts that are identical to the first embodiment.

In the fifth embodiment, a damping force varying mechanism differs 35 partially different from that of the first embodiment. That is, the damping force varying mechanism 35 of the fifth embodiment is a lid member 53 identical to that of the first embodiment is used and a case body 54 and a free piston 57 which are partially different from those of the first embodiment are used.

A cylindrical surface section 151 , a curved surface section (an inclined surface) 152 , a curved surface section (an inclined surface) 153 and a cylindrical surface portion 154 are on the inner periphery of a housing cylinder portion 75 of the housing body 54 starting at the side of a case bottom section 76 educated. The cylindrical surface section 151 has a constant diameter. The curved surface section 152 , the one with the cylindrical surface section 151 is formed in an annular shape so that its inner diameter with the distance to the cylindrical surface portion 151 increases. The curved surface section 153 , the one with the curved surface section 152 is formed in an annular shape so that its diameter with the distance to the curved surface portion 152 decreases. The cylindrical surface section 154 , the one with the curved surface section 153 has a constant diameter equal to that of the cylindrical surface portion 151 is. The curved surface sections 152 and 153 have a continuous shape and are shaped so that their cross-sections encompass a central axis of the housing body 54 have an arcuate shape. The cylindrical surface section 151 and the curved surface portion 152 on the side of the lower chamber 13th are on an inner annular protrusion (a case-side annular protrusion) 155 formed extending inward in a radial direction. The cylindrical surface section 154 and the curved surface portion 153 on the side of the upper chamber 12th are on an inner annular protrusion (a case-side annular protrusion) 156 which extends inward in a radial direction.

A cylindrical surface section 161 , a curved surface section (an inclined surface) 162 , a curved surface section (an inclined surface) 163 and a cylindrical surface portion 164 are in turn on the outer peripheral surface of a piston cylinder portion 91 of the free piston 57 starting on the side of a piston crown section 92 educated. The cylindrical surface section 161 has a constant diameter.

The curved surface section 162 , the one with the cylindrical surface section 161 is formed in an annular shape so that its diameter with the distance to the cylindrical surface portion 161 decreases. The curved surface section 163 , the one with the curved surface section 162 is formed in an annular shape so that its diameter with the distance to the curved surface portion 162 increases. The cylindrical surface section 154 , the one with the curved surface section 163 has a constant diameter equal to that of the cylindrical surface portion 161 is. The curved surface sections 162 and 163 have a continuous shape and are shaped so that their cross-sections encompass a central axis of the free piston 57 have an arcuate shape. The cylindrical surface section 161 and the curved surface portion 162 on the side of the lower chamber 13th are on an outer annular protrusion (a free piston-side annular protrusion) 165 which extends outward in a radial direction. The cylindrical surface section 164 and the curved surface portion 163 on the side of the upper chamber 12th are on an outer annular protrusion (a free piston-side, annular protrusion) 166 which extends outward in a radial direction. The curved surface sections 162 and 163 of the free piston 57 and the curved surface portions 152 and 153 of the housing body 54 are designed with the same curvature.

The damping force varying mechanism 35 (only an O-ring, an elastic body, 9 shows a natural state) 168 is between the curved surface sections 162 and 163 of the free piston 57 and the curved surface portions 152 and 153 of the housing body 54 arranged. The O-ring is in a natural state 168 formed so that its cross section including a central axis has a circular shape and it has an inner diameter which is smaller than the smallest diameter of the curved surface portions 162 and 163 of the free piston 57 and an outer diameter that is greater than the largest diameter of the curved surface portions 152 and 153 of the housing body 54 . That is, the O-ring is in engagement with both the free piston 57 as well as the housing body 44 fitted in a radial direction. The O-ring 168 holds the free piston 57 in a neutral position with respect to the housing 55 . At the same time, the O-ring makes it possible 168 the free piston 57 axially towards both the upper chamber 12th as well as the lower chamber 13th relative to the housing 55 to move and he experiences a pressure deformation against the bidirectional movement of the free piston 57 . Furthermore, the radii of curvature of the curved surface sections 152 , 153 , 162 and 163 larger than a cross-sectional radius of the O-ring 168 with a circular cross-section.

Accordingly is in the housing 55 the O-ring 168 in contact with the curved surface portion 152 and 153 . The curved surface sections 152 and 153 are in one direction of movement of the free piston 57 inclined. It also says in the free piston 57 the O-ring 168 in contact with the curved surface portions 162 and 163 . The curved surface sections 162 and 163 are in the direction of movement of the free piston 57 inclined.

The damping force varying mechanism 35 can by arranging the o-ring 168 on the curved surface portion 153 in the case body 54 by fitting the free piston 57 into the inside of the housing body 54 and the O-ring 168 by fitting the cover element 53 in the case body 54 and by swaging the housing body 54 be assembled.

In the damping force varying mechanism 35 of the fifth embodiment provide a communication chamber for the lower chamber 107 that with the upper chamber 12th via line holes 105 and 106 the piston rod 16 is in communication and a connecting chamber for the lower chamber 108 that with the lower chamber 13th via a connecting hole 87 of the case bottom section 76 is in communication, from the housing 55 , the O-ring 168 and the free piston 57 divided.

In the damping force varying mechanism 35 the fifth embodiment is the O-ring 168 between the curved surface sections 152 and 154 of the housing body 54 and the curved surface portions 162 and 163 of the free piston 57 in a neutral position of the free piston 57 arranged. For example, roll on the extension stroke when the free piston 57 move from the neutral position towards the lower chamber 13th moved, the curved surface portion 152 of the housing body 54 on the side of the lower chamber 13th and the curved surface portion 163 of the free piston 57 the O-ring on the side of the upper chamber 168 and at the same time compress the O-ring 168 in the axial and radial direction of the free piston 57 .

At the following displacement stroke when the free piston 57 towards the upper chamber 12th moves, rolling the curved surface section 152 of the housing body 54 on the side of the lower chamber 13th and the curved surface portion 163 of the free piston 57 on the side of the upper chamber 12th the O-ring 168 and at the same time release the compression of the O-ring 168 . The curved surface section then rolls 153 of the housing body 54 on the side of the upper chamber 12th and the curved surface portion 162 of the free piston 57 on the side of the lower chamber 13th the O-ring 168 and at the same time compress the O-ring 168 in the axial and radial direction of the free piston 57 .

On the following extension stroke, the curved surface section will roll 153 of the housing body 54 on the side of the upper chamber 12th and the curved surface portion 152 of the free piston 57 on the side of the lower chamber 13th the O-ring 168 and at the same time release the compression of the O-ring 168 . When the free piston 57 passes through its neutral position, the curved surface portion will roll 152 of the housing body 54 on the side of the lower chamber 13th and the curved surface portion 163 of the free piston 57 on the side of the upper chamber 12th the O-ring 168 and at the same time compress the O-ring 168 in the axial and radial direction of the free piston 57 in the same way as described above.

According to the fifth embodiment described above, since the O-ring 168 a pressure deformation through the bidirectional movement of the free piston 57 learns it is possible to use the bidirectional movement of the free piston 57 using an O-ring 168 to manage something.

[Sixth embodiment]

Next, we will focus on portions different from those of the first embodiment based mainly on 10 , a sixth embodiment is described. Furthermore, the same names and reference numbers are used for parts that are identical to the first embodiment.

In the sixth embodiment, a damping force varying mechanism is different 35 partially different from that of the first embodiment. That is, in the damping force varying mechanism 35 the fifth embodiment becomes a case body 54 identical to that of the first embodiment is used and a lid member 53 and a free piston 57 which are partially different from those of the first embodiment are used.

The cover element 53 has a lid cylinder portion 62 different from that of the first embodiment. The lid cylinder section 62 is provided with an outer annular projection (an annular projection on the housing side) 171 that extends outward in a radial direction on one side of a lid flange portion 63 of which extends. A cylindrical surface section with a small diameter 172 , a curved surface section (an inclined surface) 173 , a sloped surface portion (an inclined surface) 174 and a large diameter cylindrical surface portion 175 are in turn on an outer peripheral surface of the lid cylinder portion 62 starting on the opposite side to the cover flange section 63 educated. The small diameter cylindrical surface portion 172 has a constant diameter. The curved surface section 173 , the one with the cylindrical surface portion with a small diameter 172 is formed in an annular shape so that its diameter with the distance to the cylindrical surface portion with a small diameter 172 increases. The sloped surface section 174 connected to the curved surface portion 173 is formed so that its diameter with the distance from the curved surface portion 163 increases. The large diameter cylindrical surface portion 175 , the one with the beveled surface section 174 is connected has a constant diameter that is larger than a diameter of the cylindrical surface portion with a small diameter 172 . The curved surface section 173 , the beveled surface section 174 and the large-diameter cylindrical surface portion 175 are on the outer annular protrusion 171 educated. The curved surface section 173 is designed so that its cross section includes a central axis of the cover element 53 has an arcuate shape.

The free piston has a piston cylinder portion 91 which is partially different from that of the first embodiment. The piston cylinder section 91 is provided with an inner annular protrusion (a free piston-side annular protrusion) 181 extending inward in a radial direction in addition to an outer annular protrusion 93 protruding outward in a radial direction at an axially central position therefrom. A cylindrical surface section with a small diameter 182 , a sloped surface portion (an inclined surface) 183 , a curved surface section (an inclined surface) 184 and a large diameter cylindrical surface portion 185 are in turn on an inner peripheral surface of the piston cylinder portion 91 starting from the side of a piston crown section 92 educated. The small diameter cylindrical surface portion 182 has a constant diameter. The sloped surface section 183 , the one with the cylindrical surface section with a small diameter 182 is connected, is formed so that its diameter with the distance to the cylindrical surface portion with a small diameter 182 increases. The curved surface section 184 connected to the curved surface portion 183 is formed in an annular shape so that its diameter with the distance from the inclined surface portion 183 increases. The large diameter cylindrical surface portion 185 , the one with the beveled surface section 184 is connected has a constant diameter that is larger than a diameter of the cylindrical surface portion with a small diameter 182 . The curved surface section 184 is designed so that a cross section comprising a central axis of the free piston 57 has an arcuate shape. The curved surface section 184 , the beveled surface section 183 and the large-diameter cylindrical surface portion 185 are on the inner annular protrusion 181 educated. The piston cylinder section 91 is with a beveled surface section 186 , its diameter with the distance to the cylindrical surface section 100 large-diameter increases on an outer peripheral surface thereof on the opposite side of the cylindrical large-diameter surface portion 100 to a sloped surface section 99 Mistake.

The free piston 57 is slidable in a small diameter cylindrical surface section 81 of the housing body 54 on the small-diameter cylindrical surface portion 97 and a large diameter cylindrical surface portion 84 of the housing body 54 on the large diameter cylindrical surface portion 100 fitted. In this state are a position of the inclined surface portion 174 of the cover element 53 and a position of the curved surface portion 184 of the free piston 57 superimposed on each other in radial directions thereof. Further, in this state, there are a position of the curved surface portion 173 of the cover element 53 and a position of the tapered surface portion 183 of the free piston 57 superimposed on each other in radial directions thereof. That is, both the curved surface section 173 and the tapered surface portion 174 of the cover element 153 and both the tapered surface portion 183 as well as the curved surface portion 184 of the free piston 57 lie to each other in the direction of movement of the free piston 57 across from. Furthermore, the inclined surface portion 174 of the cover element 53 and the tapered surface portion 183 of the free piston 57 inclined to the axes thereof at the same angle. The curved surface section 184 of the free piston 57 has the same cross-sectional curvature as that of the curved surface portion 173 of the cover element 53 on. Furthermore, the curved surface parts 173 and 184 Radii of curvature that are larger than the cross-sectional radius of the O-ring 58 , which has a circular cross-section.

Hence the O-ring 58 ( 10 shows a natural state) between the inclined surface portion 183 , the curved surface section 184 and the large diameter cylindrical surface portion 185 of the free piston 57 and the tapered surface portion 174 , the curved surface section 173 and the small-diameter cylindrical surface portion 172 of the cover element 53 arranged. The O-ring is in a natural state 58 formed so that its cross section including a central axis has a circular shape and it has a smaller inner diameter than the cylindrical surface portion with a small diameter 172 of the cover element 53 and a larger outer diameter than the cylindrical large diameter surface portion 185 of the free piston 57 on. That is, the O-ring 58 is in engagement with both the free piston 57 and the cover element 53 fitted in a radial direction.

Accordingly, it says in the free piston 57 the O-ring 58 in contact with the tapered surface portion 183 , the curved surface section 184 and the large diameter cylindrical surface portion 185 . The sloped surface section 183 and the curved surface portion 184 are in the direction of movement of the free piston 57 inclined.

In the case 55 is the O-ring 58 in contact with the small diameter cylindrical surface portion 172 , the curved surface section 173 and the tapered surface portion 174 . The curved surface section 173 and the tapered surface portion 174 are to the direction of movement of the free piston 57 inclined towards.

The shortest distance between a free piston contact surface (a portion where the large diameter cylindrical surface portion 185 , the curved surface section 184 and the tapered surface portion 183 of the free piston 57 in contact with the O-ring 58 stand) and a case contact surface (a portion on which the cylindrical surface portion with a small diameter 172 , the curved surface section 173 and the tapered surface portion 174 of the housing in contact with the O-ring 58 stand), each of which is in contact with the O-ring 58 is due to the movement of the free piston 57 changed. As the shortest distance is decreased, an inclined angle of a segment representing the shortest distance increases. In other words, shapes of the cylindrical surface portion become large in diameter 185 , the curved surface section 184 and the tapered surface portion 183 and forming the small diameter cylindrical surface portion 172 , the curved surface section 173 and the tapered surface portion 174 set so that a direction of the segment that has the shortest distance between the free piston contact surface of the free piston 57 and the housing contact surface of the housing 55 is changed. In detail if the free piston 57 on the side of the lower chamber 13th in terms of the housing 55 is the shortest distance between the free piston contact surface and the housing contact surface, each of which is in contact with the O-ring 58 stands, a difference in radius between the large-diameter cylindrical surface portion 185 and the small-diameter cylindrical surface portion 172 and the inclined angle of the segment representing the shortest distance is 0 (zero). When the free piston 57 towards the upper chamber 12th relative to the housing 55 moves, the contact position of the O-ring moves 58 to the curved surface portion 173 and the curved surface portion 184 and the shortest distance therebetween is gradually reduced and at the same time the inclined angle of the segment which is the shortest distance increases.

In the damping force varying mechanism 35 In the sixth embodiment, the O-ring works 59 in the same way as in the first embodiment

In a neutral position of the free piston 57 is the O-ring 58 between the large diameter cylindrical surface portion 185 of the housing 55 and the small-diameter cylindrical surface portion 172 of the free piston 57 arranged.

For example, on the extension stroke, when the free piston is rolling from the neutral position towards the lower chamber 13th moves, the large diameter cylindrical surface portion 185 of the housing 55 and the small-diameter cylindrical surface portion 172 of the free piston 57 the O-ring 58 and consequently move the O-ring 58 towards the lower chamber 13th relative to the housing 55 .

At the following displacement stroke when the free piston 57 towards the upper chamber 12th moved, the large diameter cylindrical surface portion roll 185 of the housing 55 and the small-diameter cylindrical surface portion 172 of the free piston 57 the O-ring 58 and consequently move the O-ring 58 towards the upper chamber 12th relative to the housing 55 . Then roll the beveled surface section 183 and the curved surface portion 184 on the side of the upper chamber 12th and the curved surface portion 173 and the tapered surface portion 174 on the side of the lower chamber 13th the O-ring 58 and compress it. Further compress the inclined surface portion 183 and the curved surface portion 184 on the side of the lower chamber 13th and the curved surface portion 173 and the tapered surface portion 174 on the side of the upper chamber 12th the O-ring 58 .

On the following extension stroke, the inclined surface section loosen 183 and the curved surface portion 184 on the side of the lower chamber 13th and the curved surface portion 173 and the tapered surface portion 174 on the side of the upper chamber 12th the compression of the O-ring 58 . The sloped surface section 183 and the curved surface portion 184 on the side of the upper chamber 12th and the curved surface portion 173 and the tapered surface portion 174 on the side of the lower chamber 13th roll the O-ring 58 and at the same time release the compression of the O-ring 58 . The large diameter cylindrical surface portion 185 of the housing 55 and the cylindrical surface portion 172 with a small diameter of the free piston 57 roll the O-ring 58 and consequently they move the O-ring 58 towards the axially lower chamber 13th relative to the housing 55 . When the free piston 57 passes through its neutral position, the O-ring works 58 in the same way as described above. In the damping force varying mechanism 35 the sixth embodiment, it is possible to use the O-ring 58 into the lid cylinder section 62 introduce and free piston 57 , the O-ring 59 and the case 55 assemble in this order in a single direction, and hence the assembling efficiency of each component is improved.

[Seventh embodiment]

Next, a seventh embodiment focusing on portions different from those of the first embodiment will be based mainly on 11 , 12A and 12B described. Furthermore, the same names and reference numbers are used for parts that are identical to the first embodiment.

In the seventh embodiment, there is a lead area varying mechanism 311 that adjusts damping characteristics from outside using an actuator or manual actuation and can set a line area in the line 110 provided that from the lines 110 and 111 was selected into an upstream side and a downstream side of the free piston 57 be subdivided. The following is the power range varying mechanism 311 described.

The aforementioned line holes 105 and 106 who are taking the lead 110 form are in a piston holding element 304 the piston rod 16 educated. That is, the piston holding element 304 is with a female thread 303 that is on a male thread 301 of a rod body 302 is screwed on, provided. The female thread 303 on the side of the lower chamber 13th is called a bottom hole 312 educated. A receiving hole 315 that has a smaller diameter than the bottom hole 312 is in the lower hole 312 on the side of the lower chamber 13th educated. The aforementioned pipe hole 106 is formed from a lower portion of the receiving hole 315 towards the lower chamber 13th to happen. There are also the aforementioned line holes 105 formed to be from a wall portion of the receiving hole 315 to happen in a radial direction. Accordingly, the receiving hole is 315 between the pipe holes 105 and 106 educated.

An opening area varying element body 318 is in the receiving hole 315 of the piston retaining element 304 recorded. The opening area varying element body 318 has the shape of a lid cylinder having a cylinder section 319 and a lid portion 320 which is provided in a radially inward direction around one end of the cylinder portion 319 to close. As in 12B shown is the cylinder section 319 with openings 321 to 324 which are formed from linear holes at a plurality of locations, particularly four locations, in a radial direction, the openings 321 to 324 in this order in a circumferential direction of the cylinder portion 319 are trained. All the openings 321 to 324 have different hole diameters. In detail is the hole diameter of the opening 321 the largest, the hole diameter of the opening 322 is the next largest and the hole diameter of the opening 323 is the next largest and the hole diameter of the opening 324 is the smallest. The openings 321 to 324 are at the same position in an axial direction of the cylinder portion 319 and at different positions in a circumferential direction of the cylinder portion 319 educated. Here are the openings 321 to 324 having different diameters in four places are formed at equal intervals, and hence the openings are 321 to 324 formed with increments of 90 °. The opening 321 which has the largest diameter is smaller in diameter than the lead holes 105 on.

As in 12A shown is an annular sealing groove 329 on an outer peripheral side of the cylinder portion 319 in the circumferential direction of the cylinder portion 319 educated. The sealing groove 329 is on the opposite side to the lid section 320 behind the openings 321 to 324 arranged. In addition, there is the lid section 320 with a mounting hole 330 at the radial center thereof extending therethrough in an axial direction.

This opening area varying element body 318 is in the receiving hole 315 of the piston retaining element 304 added in a position in which the lid portion 320 on the opposite side to the conduit hole 106 is arranged in the state in which the O-ring 331 in the sealing groove 329 is held. The openings are in this state 321 to 324 flush with the pipe holes 105 in an axial direction of the piston holding member 304 . The O-ring 331 in the sealing groove 329 seals a gap between the opening area varying member body 318 and the receiving hole 315 .

The pole body 302 the piston rod 16 is provided with a through hole at the radial center thereof which extends therethrough in an axial direction. An operating rod 336 is in the through hole 335 introduced. The operating rod 336 includes an insertion shaft portion 337 that is in the rod body 302 is arranged, and a tip shank portion 338 that has a smaller diameter than the insertion shaft section 337 having. The tip shaft section 338 is from the opposite side of the cylinder section 319 into the mounting hole 330 of the cylinder section 320 of the opening area varying element body 318 fitted and pressed. A grouted section with a large diameter 339 becomes at the tip shank section 338 formed by pressing. The operating rod 336 holds the lid section 320 of the opening area varying element body 318 by means of the pressed section 339 and the insertion shaft section 337 . This becomes the opening area varying member body 318 on the operating rod 336 attached so as not to be rotated.

The operating rod 336 and the opening area varying member body 318 , both of which are integrally formed, rotate to selectively select the openings 321 to 324 with the pipe hole 105 to bring in connection. That is, the operating rod 336 and the opening area varying member body 318 constitute an opening area varying element 340 that allows an opening area with respect to the pipe hole 105 to vary. The opening area varying element 340 is in the piston rod 16 arranged.

The opening area varying element 340 is designed to be rotated with its angle of rotation by means of a pivotable actuator 342 is controlled, the one with the opposite side of the operating rod 336 from the opening area varying member body 318 connected is. The actuator 342 is controlled by a controller (not shown) and rotates the opening area varying member 340 at a suitable angle. This has the effect that one of the openings 321 to 324 which, as described above, has a different diameter selectively in communication with the lead hole 105 stands. One of the openings 321 to 324 that in connection with the pipe hole 105 and a space section 343 in the opening area varying element body 318 stands, brings the line hole 105 to do this, with the pipe hole 106 to be connected, making the line 110 is trained. As in 11 shown is an O-ring 344 in the through hole 335 of the piston rod body 302 arranged to leave a gap between the through hole 335 and the operating rod 336 to seal.

As in 11 shown is a piston rod 16 formed from the piston rod 302 who have favourited the male thread 301 formed at one end thereof and from the piston holding member 304 , one end of which is on the male thread 304 the piston rod 302 by means of the female thread 303 is screwed. A mounting stem section 321 at which one Piston body 14th is attached, a main shaft portion 20th that has a larger diameter than the mounting stem portion 21 has and a stop section 305 that extends over the main shaft section 20th extending in a radial direction are sequentially in the piston holding member 304 starting from the opposite side to the axial female thread 303 educated. A spring seat 306 is on the stop section 305 arranged to face the piston 11 to be. A coil spring 307 is on the spring seat 306 arranged to opposite the stop section 305 to be. A spring seat 308 is on the spiral spring 307 arranged to the spring seat 306 face to face. A buffer 309 is on the spring seat 308 on the opposite side to the coil spring 307 intended. When the piston rod 16 from the cylinder 10 protrudes by a predetermined amount, the buffer comes 309 in contact with the rod guide 17th . When the piston rod 16 protrudes further, the buffer slide 309 and the spring seat 308 on the piston rod 16 and simultaneously reduce a length of the spiral spring 307 between the spring seat 308 and the spring seat 306 . This creates the spiral spring 307 a resistance force against the protrusion of the piston rod 16 .

The opening area varying element 340 and the actuator 342 , in the 12A and 12B are shown constitute the lead area varying mechanism 311 out. In the lead area varying mechanism 311 it is permitted to use a management area of the line 110 that is in the piston rod 16 is formed by selecting the openings 321 to 324 that this line 110 train to vary. The lead area varying mechanism 311 is designed around the conduit area of the conduit 110 to vary in four stages, since it has four openings 321 to 324 has, which have four different diameters.

When the lead area varying mechanism 311 in the piston rod 16 is included, for example, the operating rod 336 of the opening area varying member 340 into the through hole 335 of the rod body 302 introduced. As a result, the opening area varying member body becomes 311 on which the O-ring 331 of the opening area varying member 340 was attached, in the receiving hole 315 fitted and at the same time the piston retaining element 304 on the pole body 302 screwed.

When the lead area varying mechanism 311 the opening 321 brings about with the pipe hole 105 to be in communication, the conduction area varying mechanism maximizes 311 the management area of the management 110 , that is, the line area of the smallest section. When the lead area varying mechanism 311 the opening 322 brings about with the pipe hole 105 to communicate is made by the duct area varying mechanism 311 the management area of the management 110 smaller than the case in which he had the opening 321 this brings with the pipe hole 105 to be connected. When the lead area varying mechanism 311 the opening 323 brings about with the pipe hole 105 to communicate is made by the duct area varying mechanism 311 the management area of the management 110 smaller than the case in which he had the opening 322 brings about with the pipe hole 105 to be connected. When the lead area varying mechanism 311 the opening 324 brings about with the pipe hole 105 to communicate is made by the duct area varying mechanism 311 the management area of the management 110 smaller than the case in which he had the opening 323 brings about with the pipe hole 105 to be connected.

When a piston speed is within a very low speed range (e.g. 0.05 m / s), a maximum damping force is obtained in a low frequency range. As a frequency increases, a damping force is reduced. If the management area of the line 110 however, is reduced, a cutoff frequency at which the damping force starts to be reduced can be lowered. Further, when the piston speed is within the very low speed range (e.g. 0.05 m / s), the smaller the conduction area of the conduit 110 becomes, the larger the damping force obtained in a high frequency region can become. Therefore, if a damping force characteristic is set at the piston speed around 0.05 m / s, the improvements in driving comfort and the improvement in control stability are compatible with each other.

In the shock absorber disclosed in Japanese Unexamined Utility Model Application First Publication No. H07-019642, a conduit from which an operating fluid flows out from a chamber in a cylinder through the inside of a piston rod due to the movement of a piston is formed. A free piston is provided to divide this conduit into an upstream side and a downstream side. This makes a damping force variable.

In turn, according to the seventh embodiment described above, the lines 110 and 111 from which the operating fluid from the upper chamber 12th in the cylinder 10 through the inside of the piston rod 16 by means of the movement of the piston 11 flows out, trained. The free piston 57 is provided to these lines 110 and 111 to be divided into the upstream side and the downstream side. Thereby, the damping force is developed to be changed. In addition, the Pipe area varying mechanism 311 who is able to manage the line area of the line 110 cease on the line 110 intended. Therefore, the damping force characteristic can be controlled with greater precision.

Further is the line 110 in the piston rod 16 and the lead area varying mechanism 311 comprises the opening area varying member 340 that is in the piston rod 16 is arranged and the actuator 342 , which is the opening area varying element 340 rotates. Accordingly, the conduction area of the conduit 110 can be adjusted by means of a simple and compact structure.

[Eighth embodiment]

Next, an eighth embodiment focusing on portions different from those of the seventh embodiment will be based mainly on 13th described. Furthermore, the same names and reference numbers are used for parts that are identical to the seventh embodiment.

In the eighth embodiment, a piping area varying mechanism is different 311 partially different from that of the seventh embodiment. In detail is a pipe hole 351 between a lower hole 312 and a receiving hole 315 a piston retaining element 304 educated. The pipe hole 351 has a smaller diameter than the lower hole 312 on and a larger diameter than the receiving hole 315 . A variety of pipe holes 105 is from a lower edge portion of the lead hole 351 formed along a radial direction.

A cylindrical conduit forming element 352 is in the pipe hole 351 and the receiving hole 315 of the piston retaining element 304 educated. The leadership training element 352 is with openings 353 and 354 provided at a plurality of locations, in particular two locations, along a radial direction. These openings 353 and 354 have mutually different line areas. In detail is the duct area of the opening 353 large and the lead area of the opening 354 is small. The openings 353 and 354 are in the axial and circumferential directions of the line forming element 352 trained in different positions. An annular sealing groove 359 is on an outer peripheral side of the line forming member 352 in a circumferential direction on the opposite side to the opening 353 behind the opening 354 in the axial direction of the line forming element 352 educated.

This leadership training element 352 is in the receiving hole 315 of the piston retaining element 304 fitted in a position at which the opening 354 having the small lead area on the side of the receiving hole 315 behind the opening 353 having the large piping area is placed in the state that the O-ring 360 in the sealing groove 359 is held. The openings are in this state 353 and 354 in the pipe hole 351 arranged and are with the line holes 105 in an axial direction of the piston holding member 304 aligned. The O-ring also seals in this state 360 a gap between the line forming member 352 and the receiving hole 315 from.

In the eighth embodiment, there is an operating rod 336 with a beveled shaft section 362 at a tip of an insertion shaft section 337 of a rod body 302 Mistake. The operating rod 336 is fitted so that the tapered shaft portion 362 into the lead forming element 352 is inserted and the introducer shaft section 337 on the side of the tapered shaft section 362 on an inner peripheral surface of the wire forming member 352 can slide.

The operating rod 336 is controlled by its axial position by means of a linear motion type actuator 364 , the one with the opposite side to the tapered shaft section 362 it is connected, controlled, and moves simultaneously in an axial direction, that is, moves linearly. The actuator 364 is controlled by means of a control device (not shown) and holds the operating rod 336 in a suitable position. This allows an effective volume of the plurality of openings 353 and 354 that have different lead areas which is used to connect with the lead hole 106 to be connected, controlled. A gap 365 between the pipe hole 351 and the lead formation element 352 , the openings 353 and 354 and a space section 366 on the side of the pipe hole 106 behind the operating rod 336 in the line formation element 352 causes the line holes 105 and the pipe hole 106 communicate with each other, making the line 110 is trained.

The leadership training element 352 and the operating rod 336 constitute the piping area varying mechanism 311 of the eighth embodiment, which is able to use the line area of the line 110 that is in the piston rod 16 is trained to adjust. The lead area varying mechanism 311 changes an amount of opening of the openings 353 and 354 who are taking the lead 110 train that towards the space section 366 is open. The lead area varying mechanism 311 can the operating rod 336 control in the state in which only a portion of the opening 354 with the space section 366 communicates in the state in which a portion of the openings 354 and a portion of the opening 353 in connection with the space section 366 stands in the state in which the total opening 354 and part of the opening 353 with the space section 366 is in communication or in the state in which the entire opening 354 and the entire opening 353 with the space section 366 communicates, control. Further, in each of these states, the connection amount of the openings 353 and 354 to the space section 366 by means of a position of the operating rod 336 can be set. I. E. the operating rod 336 is in the piston rod 16 arranged and moves linearly around the opening area in the duct 110 to vary.

When the lead area varying mechanism 311 the eighth embodiment in the piston rod 16 is included, for example the O-ring 360 on the lead formation element 352 is arranged, the line forming element 352 into the receiving hole 315 fitted and then the piston retaining element 304 on the pole body 302 screwed. Then the operating rod 336 in the rod body 302 from the opposite side to the piston holding element 304 introduced.

When the lead area varying mechanism 311 the eighth embodiment, the operating rod 336 advances to the maximum degree around the tapered shank portion 362 on the side of the pipe hole 106 behind the opening 354 to position, the openings are 353 and 354 not in connection with the room section 366 and the pipe hole 106 . In this state, the line area becomes the line 110 Zero (0), the smallest range. On the other hand, if the lead area varying mechanism 311 the operating rod 336 retracts to the maximum degree around the tapered shank portion 362 on the opposite side to the conduit hole 106 behind the opening 363 to position, all the openings are available 353 and 354 in connection with the room section 366 and the pipe hole 106 . In this state, the line area becomes the line 110 the largest area.

[Ninth embodiment]

Next, a ninth embodiment focusing on portions different from those of the eighth embodiment will be based mainly on 14th described. Furthermore, the same names and reference numbers are used for parts that are identical to the eighth embodiment.

In the ninth embodiment, the conduction area varying mechanism is partially different from that of the eighth embodiment. In detail there is a lower hole on the inside 312 a piston retaining element 304 a pipe hole 371 that has a smaller diameter than the bottom hole 312 has formed. On an inner side of the pipe hole 371 is a beveled hole 372 which has a smaller diameter than the pipe hole 371 has as a whole and its diameter decreases as it approaches the inside, formed. Further, is on an inside of the tapered hole 372 an opening 373 formed the same diameter as the tapered hole 372 from the small diameter side is formed. On the inside of the opening 373 is a beveled hole 374 whose diameter increases as it approaches the inside. Hence there is a lead hole 106 on the inside of the angled hole 374 educated. There are also line holes 104 , 105 on a wall portion of the pipe hole 371 formed along a radial direction.

An operating rod 336 The ninth embodiment includes an insertion shaft portion 337 and a tapered shaft portion 362 at one end of the insertion shaft section 337 is designed as in the eighth embodiment. The introductory shaft section 337 gets into the pipe hole 371 introduced and the beveled shaft portion 362 is able to make contact with the tapered hole 372 to stand and get away from the slanted hole 372 to separate.

The operating rod 336 is moved along its axial position by means of a linear movement type actuator 364 controlled, the one with the opposite side of the tapered shaft portion 362 connected therefrom and moving in an axial direction at the same time. The actuator 364 is controlled by means of a control device (not shown) and holds the operating rod 336 in a suitable position. This controls the tapered shaft portion 362 an effective volume of a gap between the tapered shaft portion 362 and the beveled hole 372 which is used to deal with the pipe holes 105 to be connected. A gap between the pipe hole 371 and the beveled hole 372 and the operating rod 336 , the opening 373 and the beveled hole 374 causes the line holes 105 and the pipe hole 106 communicate with each other, making the line 110 is trained.

The piston retaining element 304 and the operating rod 336 constitute the piping area varying mechanism 311 from who is able to determine the line area of the line 110 that is in the piston rod 16 is trained to adjust. The lead area varying mechanism 311 is capable of the management area of the line 110 by changing the gap between the tapered shaft portion 362 and the beveled hole 372 who are taking the lead 110 train, change.

When the lead area varying mechanism 311 the operating rod advances to the maximum degree around the tapered shaft portion 362 in contact with the tapered hole 372 to bring, stands the opening 373 not in connection with the pipe holes 105 . In this state, the line area becomes the line 110 equal to zero (0), the smallest range. On the other hand, if the lead area varying mechanism 311 the operating rod 336 retracts towards the maximum degree, around the tapered shank section 362 from the slanted hole 372 Separating to a maximum degree, the entire opening faces 373 in connection with the line holes 105 . In this state, the line area becomes the line 110 equal to a conduction area of the opening 373 that is, to rise to the maximum degree. Consequently, the conduction area between them is made by adjusting a gap amount between the tapered shaft portion 362 and the beveled hole 372 set. That is, even in this case, the operating rod is 336 in the piston rod 16 arranged and moves linearly around an opening area of the conduit 110 to vary. With this structure of the ninth embodiment, compared with the mechanism of the seventh embodiment that varies the conduction area in four steps, the gap is adjusted linearly. As a result, it is possible to set the damping force more uniformly.

[Tenth embodiment]

Next, a tenth embodiment will focus on portions different from those of the seventh through ninth embodiments based mainly on 15th described. Furthermore, the same names and reference numerals are used for parts that are identical to the seventh to ninth embodiments.

The tenth embodiment is a modification of a damping force varying mechanism in connection with the seventh to ninth embodiments. A damping force varying mechanism 350 the tenth embodiment can also be applied to any of the seventh to ninth embodiments.

The damping force varying mechanism 250 The tenth embodiment includes a housing 253 that consists of a housing body 251 having an approximately cylindrical shape and a bottom cover member 252 that is at one end of the case body 251 is fixed in an axial direction is constructed. The case body 251 has a cylindrical shape. A female thread 255 on which the bottom cover element 252 is screwed, a receiving hole portion 256 with a smaller diameter than the female thread 255 , a beveled hole 257 that has a smaller diameter than the receiving hole portion 256 has a female thread 258 that is on a male thread 50 a piston rod 16 is screwed, and a mounting hole portion 259 that has a larger diameter than the female thread 258 are in turn in an axial direction in the center of the case body 251 starting from the side on which the bottom cover element 252 is attached, formed. The floor cover element 252 is with a male thread 261 provided on an outer surface thereof which is on the female thread 255 is screwed. The bottom cover element 252 is with a connecting hole 262 at the center thereof which runs therethrough in an axial direction.

The case 253 includes: a pair of holders 265 and 266 that are in the receiving hole portion 256 of the housing body 251 are arranged in contact with a bottom surface of the receiving hole portion 256 and an inner surface of the bottom lid member 252 and having a bottomed cylindrical shape; a pair of spacers 267 and 268 that are in the holders 265 or. 266 are arranged; a pair of disk-shaped base plates 269 and 270 that are on opposite sides of the holder 265 and 266 in axial directions of the spacers 267 and 268 are arranged; a pair of sheet-shaped elastic elements 271 and 272 that are on opposite sides of the spacers 267 and 268 in axial directions of the base plates 269 and 270 are arranged and made of rubber; and a guide element 273 that is axially between the elastic elements 271 and 272 is arranged, the elastic elements 271 and 272 by means of the base plates 269 and 270 holds and has an approximately cylindrical shape.

The keepers 265 and 266 are with through holes 275 and 276 provided in the centers on bottom portions thereof in an axial direction. Furthermore, the holders 265 and 266 with slots 265A and 266A provided at transverse positions thereof extending from the bottom portions thereof in a radial gap between the guide member 273 and the case body 251 extend and the slots 265A and 266A extend in a radial direction and then extend in an axial direction to on the opposite sides from the bottom portions of the holders 265 and 266 to resign. Furthermore, the base plates 269 and 270 also with through holes (openings) 277 and 278 at the centers of bottom portions thereof in an axial direction. The spacers 267 and 268 are between the holders 265 and 266 and the base plates 269 and 270 held in the condition in which the through holes 275 and 276 the holder 265 and 266 always with the through holes 277 and 278 the base plates 269 and 270 can be connected. The through holes 277 and 278 have a smaller diameter than the through holes 275 and 276 on.

The guide element 273 is with an annular protruding portion 280 provided which protrudes outwardly at a predetermined intermediate axial position. The protruding portion 280 is with an annular retaining groove 282 provided on an outer periphery thereof having a sealing ring 281 holds that a gap between the housing body 251 and the protruding portion 280 sealed. Furthermore, the guide element 273 with a multitude of through holes 283 and a variety of through holes 284 provided both in a radial direction on axially opposite sides of the protruding portion 280 run away.

In addition, includes the damping force varying mechanism 250 a free piston 287 that is in the guide element 273 is fitted to in an axial direction of the guide member 273 to be slidable and a pair of coil springs (resistance element) 288 and 289 that between the free piston 287 and the base plate 269 and between the free piston 287 and the base plate 270 are arranged around the free piston 287 hold in a neutral position and provide resistance to the displacement of the free piston 287 to create. The free piston 287 comes with a pair of spring retaining holes 291 and 292 to hold the coil springs 288 and 289 on axially opposite sides thereof in the axial direction. The free piston 287 is with an annular groove portion 293 provided on an outer peripheral surface thereof which is recessed radially within an axially predetermined intermediate range. the groove section 293 switches the connection and blockage in relation to the through holes 283 and 284 according to a position of the free piston 287 relative to the guide element 273 .

The coil springs 288 and 289 cock the free piston 287 in the case 253 from axially opposite sides of the free piston 287 to the free piston 287 hold in its neutral position in front, and create a resistance against the displacement of the free piston 287 . When the free piston 287 moves from its neutral position in a direction that the coil spring 288 shortened, the elastic element gets 271 in contact with an end face of the free piston 287 in an axial direction, thereby reducing a length of the coil spring 288 regulate towards the shortest length and the free piston 287 with the base plate 269 to contact. When the free piston 287 moves from its neutral position in a direction determined by the coil spring 289 shortened, the elastic element gets 272 in contact with the other end face of the free piston 287 in an axial direction, thereby reducing a length of the coil spring 289 is regulated towards the shortest length and the free piston 287 with the base plate 270 is contacted.

In the damping force varying mechanism 250 the tenth embodiment becomes a connecting chamber for the upper chamber 295 between the guide element 273 , the free piston 287 and the base plate 269 on the side of the piston rod 16 educated. The connecting chamber for the upper chamber 295 is in communication with an upper chamber 12th (not in 15th shown) via a pipe hole 106 the piston rod 16 , the through hole 275 of the holder 265 on the side of the piston rod 16 , and the through hole 277 the base plate 269 on the side of the piston rod 16 . A connecting chamber for the lower chamber 269 is between the guide element 273 , the free piston 287 and the base plate 270 on the opposite side of the piston rod 16 educated. The connecting chamber for the lower chamber 269 is in communication with an upper chamber 13th through the through hole 287 the base plate 270 , the through hole 276 of the holder 266 on the opposite side to the piston rod 16 , and the connection hole 262 of the bottom cover element 252 . The connecting chamber for the upper chamber 295 and the through hole 277 put a line 110 dar and the connecting chamber for the lower chamber 296 and the through hole 278 put a line 111 represent.

In the damping force varying mechanism 250 the tenth embodiment when the free piston 287 is arranged in its neutral position, the groove portion stands 293 of the free piston 287 in connection with all of the through holes 283 and 284 of the guide element 273 and the slots 265A and 266A the holder 265 and 266 . From this state, for example during an extension stroke, when the free piston 287 moves from its neutral position towards the axially lower chamber 13th relative to the housing 253 moves, the free piston stretches 287 the spiral spring 288 on the opposite side to the axially lower chamber 13th and pulls the spiral spring at the same time 289 on the side of the axially lower chamber 13th together, causing an oil on the side of the upper chamber 12th (not shown in 15th ) into the connecting chamber for the upper chamber 295 flows. At this point the free piston takes effect 287 that the groove section 293 the through holes 283 on the opposite side to the axially lower chamber 13th closes and with only the through holes 284 on the side of the axially lower chamber 13th communicates.

At the following displacement stroke when the free piston 287 to the opposite side to the axially lower chamber 13th moves, the free piston stretches 287 the spiral spring 289 on the side of the axially lower chamber 13th and simultaneously shortens the spiral spring 288 on the opposite side to the axially lower chamber 13th which causes an oil on the side of the lower chamber 13th into the connecting chamber for the lower chamber 296 flows. At this point the free piston takes effect 287 that the groove section 293 the through holes 284 on the side of the lower chamber 13th closes and only in connection with the through holes 283 on the opposite side to the axially lower chamber 13th stands after the groove section 293 with the through holes 283 and 284 was in communication on the axially opposite sides thereof.

At the extension stroke when the free piston 287 to the side of the lower chamber 13th relative to the housing 253 moves, the free piston stretches 287 the spiral spring 288 on the opposite side to the lower chamber 13th and pulls the spiral spring at the same time 289 on the side of the lower chamber 13th together. After the free piston 287 has passed through its neutral position at which the groove portion 293 with the through holes 283 and 284 communicates on the axially opposite sides thereof, the free piston acts 287 in the same way as described above.

According to the tenth embodiment, as described above, since the resistance to the displacement of the free piston 287 from the coil springs 288 and 289 is generated, it is possible to improve the durability.

Further, in the tenth embodiment, the elastic members 271 and 272 be formed from a material having elasticity such as rubber, gel enclosed in a bag, etc., in addition to a coil spring or a leaf spring.

[Eleventh embodiment]

Next, an eleventh embodiment focusing on portions different from those of the seventh through ninth embodiments will be mainly based on 16 described. Furthermore, the same names and reference numerals are used for parts that are identical to the seventh to ninth embodiments.

The eleventh embodiment is a modification of a damping force varying mechanism with respect to the seventh through ninth embodiments. A damping force varying mechanism 400 the eleventh embodiment can also be applied to any one of the seventh to ninth embodiments.

The damping force varying mechanism 400 the eleventh embodiment includes a housing 405 , a free piston 407 that is slidable into the housing 405 is inserted, an O-ring (a resistance element, an elastic body, or a single elastic body) 408 , which serves as an elastic body on the displacement side, that between the free piston 407 and a cover element 402 of the housing 405 arranged, and an O-ring (a resistance element, an elastic body, or the other elastic body) 409 that acts as an elastic body on the extension side, between the free piston 407 and a case body 403 of the housing 405 is arranged, serves. The case 405 comprises the cover element 402 and the case body 403 . The cover element 402 is with a female thread 401 provided that on a male thread 50 a piston retaining element 304 that is a piston rod 16 trains, is screwed on. The case body 403 has an approximately cylindrical shape and is on the cover member 402 fixed so that an opening side is closed from one end thereof. The O-ring 408 undergoes pressure deformation when the free piston 407 in the direction of the axial cover element 402 relative to the housing 405 emotional. The O-ring 409 undergoes a compression deformation when the free piston 407 towards the opposite side to the side described above relative to the housing 405 emotional. Furthermore, for the sake of simplicity, the O-rings are shown in FIG 16 also shown in a natural state. Especially since the O-ring 409 Serving as a seal is the O-ring 409 preferably arranged to be deformed normally in an attached state (in a non-circular cross-section).

The cover element 402 is mainly formed by cutting. The cover element 402 includes an inner lid cylinder portion 412 , which has an approximately cylindrical shape, a disk-shaped lid base plate portion 413 extending from an axial end of the inner lid cylinder portion 412 extending in a radially outward direction and an outer lid cylinder portion 414 extending from an outer peripheral side of the lid base plate portion 413 in the same direction as the inner lid cylinder portion 412 extends.

The female thread 401 is on an inner periphery of the inner lid cylinder portion 412 educated. The female thread 401 extends in a radially inward direction at an axially intermediate position. Furthermore are a small diameter cylindrical surface portion 416 , a curved surface section 417 , and a large diameter cylindrical surface portion 418 in turn on an inner peripheral surface of the outer lid cylinder portion 414 starting from the side of the lid base plate section 413 educated. The small diameter cylindrical surface portion 416 has a constant diameter. The curved surface section 417 , the one with the cylindrical surface portion with a small diameter 416 is formed in an annular shape so that its diameter with the distance to the cylindrical surface portion of small diameter 416 increases. The large diameter cylindrical surface portion 418 , the one with the curved surface section 417 has a constant diameter larger than the large diameter cylindrical surface portion 416 . The curved surface section 417 is designed so that its cross section includes a central axis of the cover element 402 has an arcuate shape.

The case body 403 is mainly formed by cutting. The case body 403 has an approximately cylindrical shape and is provided with an inner annular projection 420 on an axial side thereof extending in a radially inward direction. The small diameter cylindrical surface portion 421 , a curved surface section 422 , a large diameter cylindrical surface section 423 and a cylindrical fitting surface portion on the large-diameter side 424 that has a larger diameter than the cylindrical large-diameter surface portion 423 are in turn on the inner peripheral surface of the case body 403 starting from an axial side of the housing body 403 educated. The small diameter cylindrical surface portion 421 has a constant diameter. The curved surface section 422 , the one with the cylindrical surface portion with a small diameter 421 is formed in an annular shape so that its diameter with the distance to the cylindrical surface portion with a small diameter 421 increases. The large diameter cylindrical surface portion 423 , the one with the curved surface section 422 is connected has a constant diameter which is larger than the cylindrical surface portion with a small diameter 421 . The cylindrical fitting surface portion on the large diameter side 424 attached to the large diameter cylindrical surface portion 423 abuts in an axial direction has a larger diameter than the cylindrical large-diameter surface portion 423 on. The curved surface section 422 is designed so that its cross section includes a central axis of the housing body 403 has an arcuate shape. The small diameter cylindrical surface portion 421 and the curved surface portion 422 are on the inner annular protrusion 420 educated.

The outer lid cylinder section 414 of the cover element 402 is in the fitting surface portion on the large-diameter side 424 this case body 403 fitted along its length. By fitting the outer lid cylinder portion 414 into the fitting surface portion on the large-diameter side 424 , the large diameter cylinder surface portion travels 418 of the outer lid cylinder section 414 having a large diameter cylinder surface portion 423 of the housing 403 without a difference in altitude. The curved surface section 417 is on an inner annular protrusion 425 of the cover element 402 which extends in a radially inward direction across the large diameter cylinder surface portion 418 and the large-diameter cylinder surface portion 423 extends away. So far, the case body was 403 described as approximating to a cylinder, although the inner peripheral surface thereof preferably has a cylindrical cross section, the outer peripheral surface of the case body may 403 have a non-circular cross-section, such as a polygonal cross-section.

In the case of the housing body 403 becomes the cover element 402 into the cylindrical fitting surface portion on the large-diameter side 424 by means of the outer lid cylinder section 414 , wherein the outer lid cylinder portion 414 directed in one direction, fitted. In this state, an end portion that forms a portion of the cylindrical fitting surface portion on the large-diameter side becomes 424 of the housing body 403 forms and from the cover element 402 extends, pressed on the inside. This becomes the cover element 402 on the case body 403 attached and integrated into it. In this way, form the case body 403 and the cover element 402 that are integrated with each other, the housing 405 out.

The free piston 507 is mainly formed by cutting. The free piston 407 includes a piston cylinder portion 428 , which has an approximately cylindrical shape, and a piston closing plate portion 429 , which is an axial end of the piston cylinder portion 428 locks. The piston closing plate section 428 is with one outer annular projection 430 at the axial center thereof extending in a radially outward direction.

A cylindrical surface section with a small diameter 433 , a curved surface section 434 , a large diameter cylindrical surface section 435 , a curved surface section 436 , and a cylindrical surface portion with a small diameter 437 are in turn on the outer peripheral surface of the piston cylinder portion 428 starting from the side of the axial piston closing plate section 429 educated. The curved surface section 434 , the large diameter cylindrical surface portion 435 and the curved surface portion 436 are on the outer annular protrusion 430 educated.

The small diameter cylindrical surface portion 433 has a constant diameter. The curved surface section 434 , the one with the cylindrical surface portion with a small diameter 433 is formed in an annular shape so that its diameter with the distance to the cylindrical surface portion with a small diameter 433 increases. The large diameter cylindrical surface portion 435 , the one with the curved surface section 434 is connected has a constant diameter larger than that of the cylindrical surface portion with a small diameter 433 . The curved surface section 434 is designed so that its cross section includes a central axis of the free piston 407 has an arcuate shape.

The curved surface section 436 , the one with the large-diameter cylindrical surface portion 435 is formed in an annular shape so that its diameter with the distance to the large-diameter cylindrical surface portion 435 decreases. The curved surface section 436 is with the small diameter cylindrical surface portion 437 connected. The small diameter cylindrical surface portion 437 has a constant diameter equal to that of the small-diameter cylindrical surface portion 433 is. The curved surface section 436 is designed so that its cross section includes a central axis of the free piston 407 has an arcuate shape. The outer protrusion 430 is symmetrical with respect to a plane passing through an axially central position thereof. The free piston 407 is with a multitude of pipe holes 438 at the axially central position of the outer annular projection 430 provided in a variety of locations. The pipe holes 438 extend through the outer annular protrusion 430 in a radial direction and are in a circumferential direction of the free piston 407 spaced at predetermined intervals.

After the free piston 407 in the case 405 has been arranged, the cylindrical surface portion becomes large in diameter 435 of the free piston 407 slidable in the large diameter cylindrical surface portion 423 of the housing body 403 and the large-diameter cylindrical surface portion 418 of the cover element 402 fitted. The free piston 407 is formed so that a cylindrical surface portion with a small diameter 433 and the other cylindrical small diameter surface portion 437 are able to adhere to the cylindrical surface portion with a small diameter 421 of the housing body 403 or the small-diameter cylindrical surface portion 416 of the outer lid cylinder section 414 of the cover element 402 to slide. After the free piston 407 in the case 405 has been arranged, a position of the curved surface portion are superimposed 422 of the housing body 403 and a position of the curved surface portion 434 of the free piston 407 in radial directions thereof. As a result, the curved surface portion lies 422 of the housing body 403 and the curved surface portion 434 of the free piston 407 each other in a direction of movement of the free piston 407 across from. In addition, are a position of the curved surface portion 417 and the outer lid cylinder portion 414 of the cover element 402 and a position of the curved surface portion 436 of the free piston 407 are superposed on each other in a radial direction thereof. As a result, the curved surface portion lies 417 of the cover element 402 and the curved surface portion 436 of the free piston 407 each other in a direction of movement of the free piston 407 across from.

Consequently, there is between the cylindrical surface portion of small diameter 433 and the curved surface portion 434 of the free piston 407 and the curved surface portion 422 and the large diameter cylindrical surface portion 423 of the housing body 403 , in other words between the outer annular projection 430 of the free piston 407 and the inner annular protrusion 420 of the housing 405 an O-ring 409 ( 16 shows a natural state). The O-ring is in a natural state 409 designed so that its cross section comprising a central axis has a circular shape, a smaller one Diameter than the small diameter cylindrical surface portion 433 of the free piston 407 and has a larger outer diameter than the cylindrical surface portion with a large diameter 423 of the housing body 403 having. In other words, the O-ring is in interference with both the free piston 407 as well as the housing body 403 fitted in a radial direction.

Further, there is a large diameter between the cylindrical surface portion 418 and the curved surface portion 417 of the cover element 402 and the curved surface portion 436 and the small-diameter cylindrical surface portion 437 of the free piston 407 , in other words between the outer annular projection 430 of the free piston 407 and the other inner annular protrusion 425 of the housing 405 an O-ring 408 ( 16 shows a natural state). The O-ring is in a natural state 408 also formed so that its cross section including a central axis has a circular shape and it has a smaller inner diameter than the cylindrical surface portion with a small diameter 437 of the free piston 407 on and a larger outer diameter than the cylindrical large diameter surface portion 418 of the cover element 402 . That is, the O-ring 408 will also affect both the free piston 407 and the case 405 fitted in a radial direction.

Both of the o-rings 408 and 409 are the same size. Both of the o-rings 408 and 409 hold the free piston 407 in a predetermined neutral position with respect to the housing 405 and allow the free piston 57 axially toward both the axially upper and lower chambers 12th and 13th relative to the housing 405 to move.

In the free piston 405 is the O-ring 408 in contact with the small diameter cylindrical surface portion 437 and the curved surface portion 436 . The curved surface section 436 is in the direction of movement of the free piston 407 inclined. It is also in the housing 405 the O-ring 408 in contact with the large diameter cylindrical surface portion 418 and the curved surface portion 417 . The curved surface section 417 is in the direction of movement of the free piston 407 inclined.

In other words, it is the outer annular protrusion 430 on the outer periphery of the free piston 407 intended. Axially opposed surfaces of the outer annular projection 430 form the curved surface section 434 or the curved surface section 436 out. On the inner circumference of the case 405 are the inner annular protrusion 420 showing the curved surface section 422 forms, and the inner annular projection 425 showing the curved surface section 417 forms on opposite sides of the outer radial projection 430 intended. The O-ring 409 and the O-ring 408 are between the outer annular projection 430 and the inner annular protrusion 420 and between the outer annular projection 430 or the inner annular projection 425 intended.

The shortest distance between sections where the O-ring 409 is in contact with a free piston contact surface (a portion where the cylindrical surface portion with a small diameter 433 and the curved surface portion 434 of the free piston 407 in contact with the O-ring 409 stand) and a case contact surface (a portion where the cylindrical surface portion with a large diameter 423 and the curved surface portion 422 of the housing 405 in contact with the O-ring 409 stand) is caused by the movement of the free piston 407 changed. When the shortest distance changes, the direction of a segment that represents the shortest distance changes. In other words, the shapes of the cylindrical surface portion become small in diameter 433 and the curved surface portion 434 and the shapes of the large-diameter cylindrical surface portion and the curved surface portion 422 set so that the direction of the segment that has the shortest distance between the sections where the O-ring is in contact with the free piston contact surface of the free piston 407 and the housing contact surface of the housing 405 stands, changes. In detail if the free piston 407 on the side of the axially upper chamber (a top of 16 ) in relation to the housing 405 is arranged, has the shortest distance between the sections where the O-ring 409 in contact with the free piston contact surface and the housing contact surface is a difference in radius between the large diameter cylindrical surface portion 423 and the small-diameter cylindrical surface portion 433 on (there is a difference in radius between an outer and an inner diameter of the O-ring 409 is greater than the difference in radius between the large diameter cylindrical surface portion 423 and the small-diameter cylindrical surface portion 433 , becomes the O-ring 409 compressed by the pressure difference and the deformed portion, that is, the segment with the shortest distance, has an inclined angle equal to zero (0)). On the other hand, if the free piston 407 towards the axially lower chamber 13th (a lower page of 16 ) relative to the housing 405 moved, the sections are in contact with the O-ring 409 the curved surface portion 434 and the curved surface portion 422 and the position where the O-ring 409 is deformed to a maximum degree pressure, that is, the segment with the shortest distance, has an inclined angle different from zero (0).

Similarly, the shortest distance between sections where the O-ring is located 408 in contact with the free piston contact surface (a portion where the cylindrical surface portion with a small diameter 437 and the curved surface portion 436 of the free piston 407 in contact with the O-ring 408 stand) and a housing contact surface (a portion where the cylindrical surface portion with a large diameter 418 and the curved surface portion 417 of the housing 405 in contact with the O-ring 408 stand) stands by the movement of the free piston 407 changed. When the shortest distance changes, the direction of a segment that represents the shortest distance changes. In other words, the shapes of the cylindrical surface portion become small in diameter 437 and the curved surface portion 436 and the shapes of the large diameter cylindrical surface portion 418 and the curved surface portion 417 set so that the direction of the segment that has the shortest distance between the sections where the o-ring 408 in contact with the free piston contact surface of the free piston 407 and the housing contact surface of the housing 405 stands, changes. In detail if the free piston 407 on the side of the axially lower chamber 13th (a subpage of 16 ) in relation to the housing 405 is arranged, has the shortest distance between the sections where the O-ring 408 in contact with the free piston contact surface and the housing contact surface is a difference in radius between the large diameter cylindrical surface portion 418 and the small-diameter cylindrical surface portion 437 on (because there is a difference in radius between the outer and inner diameter of the O-ring 408 is greater than the difference in radius between the large diameter cylindrical surface portion 418 and the small-diameter cylindrical surface portion 437 , becomes the O-ring 408 deformed from the difference by pressure and the deformed portion, that is, the segment with the shortest distance, has an inclined angle equal to zero (0)). On the other hand, if the free piston 407 towards the axially lower chamber 13th (a top of 16 ) relative to the housing 405 moved, the sections are in contact with the O-ring 408 the curved surface portion 417 and the curved surface portion 436 and the position where the O-ring 408 , is deformed to a maximum degree by compression, that is, the segment with the shortest distance, has an inclined angle different from zero (0).

Furthermore, the damping force varying mechanism 400 are assembled, for example, by inserting the O-ring 409 in the case body 403 up to a position of the curved surface section 422 by fitting the free piston 407 on the side of the case body 403 and the O-ring 409 by inserting the O-ring 408 up to a position of the curved surface section 436 between the case body 403 and the free piston 407 and by pressing the cover element 402 with the case body 403 . Consequently, the damping force varying mechanism becomes 400 pre-assembled in this way by screwing the female thread 401 on the male thread 50 of the fastening shaft portion 21 the piston rod 16 attached. At this point the lid base plate section comes 413 of the housing 405 in contact with a valve regulating element 47a . The outer diameter of the damping force varying mechanism 400 , ie, the outer diameter of the case body 403 , is set to be smaller than the inner diameter of the cylinder to the extent that it does not act as a flow conduction resistance 10 .

The upper chamber 12th is in communication with a pressure chamber 440 that are in the housing 405 of the damping force varying mechanism 400 by means of the line holes 105 and 106 of the piston retaining element 304 the piston rod 16 is trained. The upper chamber is in detail 12th in connection with a connecting chamber for the upper chamber 441 the pressure chamber 440 going through the housing 405 , the O-ring 408 and the free piston 407 is determined. It is also the lower chamber 13th permitted in connection with the housing 405 via a gap between the piston cylinder section 428 of the free piston 407 to stand out from the case 405 and the inner annular protrusion 420 of the housing 405 extends. In detail it becomes the lower chamber 413 allowed with the connecting chamber for the lower chamber 442 the pressure chamber 440 in the case 405 to be in communication, and the connecting chamber for the lower chamber 42 is from the housing 405 , the O-ring 409 and the free piston 407 set.

In the eleventh embodiment, the plurality are lead holes 438 by the outer annular protrusion 430 extend in a radial direction at the axially central position of the outer annular protrusion 430 of the free piston 407 educated. This means that the connecting chamber stands for the upper chamber 441 always in connection with a chamber 444 by the housing 405 , the O-ring 408 and the O-ring 409 and the Free piston 407 via the line holes 438 is surrounded. In other words, the lead holes lead 438 Oil from the connecting chamber for the upper chamber 441 into the chamber 444 between the one O-ring 408 and the other O-ring 409 . Furthermore, as the lead holes 438 in the outer annular projection 430 of the free piston 407 are formed, the line holes are 438 with neither one O-ring 408 nor the other O-ring 409 through a range of motion of the free piston 407 relative to the housing 405 through in contact.

The O-ring 409 that is between the case body 403 and the free piston 407 is arranged, is arranged to be between the housing 405 and the free piston 407 to seal at all times and blocks the connection between the connecting chamber for the upper chamber 441 and the connecting chamber for the lower chamber 442 and between the chamber 444 and the connecting chamber for the lower chamber 442 anytime.

The pipe holes 105 and 106 and the connecting chamber for the upper chamber 441 form the line 110 from which the oil is from one chamber, the upper chamber 12th , in the cylinder 10 due to the movement of the piston 11 towards the upper chamber 12th flows out. The connecting chamber for the lower chamber 442 forms the line 111 from which the oil from the other chamber, the lower chamber 13th , in the cylinder 10 due to the movement of the piston 11 towards the lower chamber 13th flows out. Accordingly, the housing 405 part of the line 110 which is formed therein as a flow line, and has the entire line 111 which is formed therein as a flow line. The free piston 407 is movable in the pressure chamber 440 in the case 405 introduced, the pressure chamber 440 between the lines 110 and 111 is provided. The free piston 407 divides the lines 110 and 111 into two areas, ie, upstream and downstream areas. The O-rings 408 and 409 that between the free piston 407 and the case 405 are arranged and which are arranged on opposite sides in a sliding direction of the free piston, generate a resistance against the displacement of the free piston 407 . That is, the O-ring 408 creates an elastic force when the free piston 407 towards one chamber, the upper chamber 12th , relative to the housing 405 moved and the O-ring 409 creates an elastic force when the free piston 407 towards the other chamber, the lower chamber 13th , relative to the housing 405 emotional.

In the eleventh embodiment, as described above, the O-rings 408 and 409 made of a rubber material, also as components for applying a pretensioning force to the free piston 407 used to the free piston 407 to return to its neutral position. At the neutral position of the free piston 407 become the O-rings 408 and 409 that between the free piston 407 and the case 405 are arranged between the large-diameter cylindrical surface portion 418 of the cover element 402 and the small-diameter cylindrical surface portion 437 of the free piston 407 and between the large diameter cylindrical surface portion 423 of the housing body 403 and the small-diameter cylindrical surface portion 433 of the free piston 407 arranged.

In the case of the extension stroke, for example, when the free piston 407 move from its neutral position towards the lower chamber 13th relative to the housing 405 moved, the large diameter cylindrical surface portion roll 423 of the housing 405 and the small-diameter cylindrical surface portion 433 of the free piston 407 together the O-ring 409 , ie, rotate the O-ring 409 so that inner and outer diameter sides move in opposite directions and move the O-ring 409 towards the lower chamber 13th relative to the housing 405 . The curved surface section then rolls 422 of the housing 405 on the side of the upper chamber 12th and the curved surface portion 434 of the free piston 407 on the side of the lower chamber 13th the O-ring 409 and at the same time compress the O-ring 409 in the axial and radial direction of the free piston 407 . Then compress the curved surface section 422 of the housing 405 on the side of the lower chamber 13th and the curved surface portion 434 of the free piston 407 on the side of the upper chamber 12th the O-ring 409 in the axial and radial directions of the free piston 407 . Also roll on the extension stroke when the free piston 407 move from its neutral position towards the lower chamber 13th relative to the housing 405 moved, the large diameter cylindrical surface portion 418 of the housing 405 and the small-diameter cylindrical surface portion 437 of the free piston 407 together the O-ring 408 and move the O-ring 408 towards the lower chamber 13th relative to the housing 405 .

At this point there is an area where the O-ring 409 between the large diameter cylindrical surface portion 423 of the housing 405 and the small-diameter cylindrical surface portion 433 of the free piston 407 is rolled, and an area where the O-ring 409 between the curved surface portion 422 of the housing 405 and the curved surface portion 434 of the free piston 407 is rolled, rolling areas where the O-ring 409 is rolled at a position that is from a downstream end within a range of motion of the free piston 407 is separated. Further, at the position separated from the downstream side end, the rolling area is a moving area in which the O-ring 409 in a direction of movement of the free piston 407 moved in the state in which the O-ring 409 in contact with both the housing 405 as well as the free piston 407 stands. The term “moving” defines that at least one downstream end position (a lower end position in 16 ) of the O-ring 409 is moved in the direction of movement of the free piston.

There is also an area where the O-ring 409 between the curved surface portion 422 of the housing 405 and the curved surface portion 434 of the free piston 407 is compressed, a movement direction deformation area in which the O-ring 409 an elastic deformation in the direction of movement of the free piston 407 at the downstream end within the range of motion of the free piston 407 learns. The term “elastic deformation in the moving direction deformation range” is defined as a deformation when an upstream end position (an upper end position in 16 ) of the O-ring 409 is moved in the direction of movement of the free piston but a downstream end position is not changed. In this embodiment, the rolling area and the moving area partially overlap at the moving direction deformation area.

On the following displacement stroke, when the free piston moves towards the upper chamber 12th relative to the housing 405 moves, solve the curved surface portion 422 of the housing 405 on the side of the upper chamber 13th and the curved surface portion 434 of the free piston 407 on the side of the upper chamber 12th the compression of the O-ring 409 . The curved surface section then rolls 422 of the housing 405 on the side of the upper chamber 12th and the curved surface portion 434 of the free piston 407 on the side of the lower chamber 13th the O-ring 409 and release the compression of the O-ring at the same time 409 further. Then roll the cylindrical surface portion with a large diameter 423 of the housing 405 and the small-diameter cylindrical surface portion 433 of the free piston 407 together the O-ring 409 and move the O-ring simultaneously 409 towards the upper chamber 12th relative to the housing 405 . Further, in the case of the O-ring, roll at this time 408 the large diameter cylindrical surface portion 418 of the housing 405 and the small-diameter cylindrical surface portion 437 of the free piston 407 together the O-ring 408 and move the O-ring 408 towards the upper chamber 12th relative to the housing 405 . The curved surface section then rolls 417 of the housing 405 on the side of the lower chamber 13th and the curved surface portion 436 of the free piston 407 on the side of the upper chamber 12th together the O-ring 408 and simultaneously compress the O-ring 408 in the axial and radial directions of the free piston 407 . The curved surface section then compresses 417 of the housing 405 on the side of the upper chamber 12th and the curved surface portion 436 of the free piston 407 on the side of the lower chamber 13th the O-ring 408 in the axial and radial directions of the free piston 407 .

At this point there is an area where the O-ring 408 between the cylindrical this time large diameter 418 of the housing 405 and the small diameter cylindrical one at this point 437 of the free piston is rolled and an area where the O-ring 408 between the curved surface portion 417 of the housing 405 and the curved surface portion 436 of the free piston 407 is rolled, rolling areas where the O-ring 408 at a position that is from a downstream side end within the range of movement of the free piston 407 is separated, is rolled. Further, at the position separated from the downstream side end, the rolling area is a moving area in which the O-ring 408 in the direction of movement of the free piston 407 moved in the state in which the O-ring 408 in contact with both the housing 405 as well as the free piston 407 stands. The term “moving” defines that at least one downstream end position (an upper end position in 16 ) of the O-ring 408 is moved in the direction of movement of the free piston.

There is also an area where the O-ring 408 between the curved surface portion of the housing 405 and the curved surface portion 436 of the free piston 407 is compressed, a movement direction deformation area in which the O-ring 408 an elastic deformation in the direction of movement of the free piston 407 at the downstream end within the range of motion of the free piston 407 learns. The term “elastic deformation in the movement direction deformation range” is defined as a deformation when a downstream end position (a lower end position in 16 ) of the O-ring 408 is moved in the direction of movement of the free piston, but an upstream end position is not changed. In this embodiment, the rolling area and the moving area partially overlap in the moving direction deformation area.

On the following extension stroke, the curved surface section loosen 417 of the housing 405 on the side of the upper chamber 12th and the curved surface section 436 of the free piston 407 on the side of the lower chamber 13th the compression of the O-ring 408 . The curved surface section then rolls 417 of the housing 405 on the side of the lower chamber 13th and the curved surface portion 436 of the free piston 407 on the side of the upper chamber 12th the O-ring 408 and release the compression of the O-ring at the same time 408 further. Then roll the cylindrical surface portion with a large diameter 418 of the housing 405 and the small-diameter cylindrical surface portion 437 of the free piston 407 together the O-ring 408 and move the O-ring simultaneously 408 towards the lower chamber 13th relative to the housing 405 . Further, in the case of the O-ring, roll at this time 409 the large diameter cylindrical surface portion 423 of the housing 405 and the small-diameter cylindrical surface portion 433 of the free piston 407 together the O-ring 409 and move the O-ring 409 towards the lower chamber 13th relative to the housing 405 . Hence when the O-ring 407 passes through its neutral position, the O-rings work 408 and 409 in the same way as described above.

Then the o-rings 408 and 409 deformed by compression in the moving direction in the moving direction deformation area.

Here the characteristic curve of a load points over the displacement of the free piston 407 that are from the O-rings 408 and 409 made of a rubber material, has a non-linear characteristic. In other words, the load characteristic approximates a linear characteristic within a predetermined range in front of and behind the neutral position of the free piston 407 . As well as going beyond the predetermined range, an increasing degree of the load increases smoothly with respect to the displacement. As described above, as the amplitude of the piston 11 also in the range in which the operating frequency of the piston 11 is high, is low, the displacement of the free piston becomes 407 also low and the free piston 407 acts before and after its neutral position within the linear characteristic range. This causes the free piston to move 407 simple and vibrates in resonance with the vibration of the piston 11 to reduce the generated damping force of the damping force generating mechanisms 32a and 32b to contribute.

On the other hand, because the amplitude of the piston 11 increases in the range in which the operating frequency of the piston 11 is small, the displacement of the free piston increases 407 and the free piston is operated within a non-linear characteristic range. This makes it free for the piston 407 difficult to move in a gradual and smooth manner, and it is difficult to generate the damping force of the damping force generating mechanism 32a and 32b to reduce.

According to the eleventh embodiment described above, the lead holes are 438 provided to the operating fluid in the chamber 444 between the O-ring 408 and the O-ring 409 respectively. Therefore, in the process of assembling the shock absorber, it is difficult to get air out of the chamber 444 bring out and then the chamber 444 to be filled with the operating fluid. This makes it possible to simply change the damping force in response to the frequency as described above. Ie if the air is not out of the chamber 444 is taken out, the air is compressed when the free piston 407 is operated and an internal pressure of the chamber 444 rises. Therefore, there is a possibility of increasing a clamping force of the O-rings 408 and 409 whereby the operation of the free piston 407 could be affected. However, in this embodiment, the lead holes are 438 provided, making it possible to operate the free piston 407 from being affected.

Furthermore, the line holes 438 in the free piston 407 formed at positions that are in contact with neither one O-ring 408 nor the other O-ring 409 stand. It is therefore possible to increase the durability of the O-rings 408 and 409 to prevent it from contacting the lead holes 438 with the O-rings 408 and 409 to be reduced. Accordingly, it is expected that the durability of the O-rings 408 and 409 increases.

According to the above-described embodiments, the shock absorber includes: a cylinder in which an operating fluid is sealed; a piston slidably fitted in the cylinder and dividing the inside of the cylinder into two chambers; a piston rod connected to the piston and extending outside of the cylinder; first and second conduits from which the operating fluid flows out from one of the chambers of the interior of the cylinder due to the movement of the piston; a damping force generating mechanism that is disposed on the first conduit and generates a damping force; a housing in which a flow conduit of at least a portion of the second conduit is formed; a free piston movably disposed in the housing and dividing the second conduit into an upstream side and a downstream side; and one or more elastic bodies disposed between the free piston and the housing. The shock absorber is formed such that a free piston contact surface of the free piston with which the elastic body is in contact and / or a housing contact surface of the housing with which the elastic body is in contact is an inclined surface which is inclined in a moving direction of the free piston, and a shortest distance between a portion that is in contact with the elastic body within the free piston contact surface and a portion that is in contact with the elastic body within the housing contact surface by the movement of the free piston is changed. Therefore, when the damping force is changed in response to the operating frequency of the piston, it is possible to smoothly change the damping force.

Furthermore, the inclined surface of the free piston contact surface and / or the housing contact surface has a curved surface. Therefore, it is possible to change the damping force more smoothly.

Further, the elastic body has a circular cross section, and the radius of curvature of the curved surface and the inclined surface is larger than the cross sectional radius of the elastic body. Therefore, it is possible to change the damping force more smoothly.

The inclined surface of the free piston contact surface and / or the housing contact surface is formed so that when the shortest distance between the free piston contact surface and the housing contact surface becomes small, an inclined angle increases. Therefore, it is possible to change the damping force more smoothly.

The free piston contact surface and the housing contact surface have a portion that is opposite to the direction of movement of the free piston. Therefore, it is possible to adequately compress the elastic body.

The elastic body includes an elastic body that experiences compression deformation when the free piston moves in one direction and the other elastic body that experiences compression by deformation when the free piston moves in the other direction. Therefore, in both the extension stroke and the compression stroke, it is possible to smoothly change the damping force.

A flange portion with the inner and outer peripheries serving as the inclined surface is provided at one end of the free piston. An extension portion that extends into a cylinder portion of the free piston is provided on a portion of the housing. One elastic body is arranged to come into contact with the inner peripheral surface of the flange portion and the extension portion, and the other elastic body is arranged to come into contact with the outer peripheral surface of the flange portion and an inner peripheral surface of the housing. Therefore, the assembling efficiency of this component becomes good.

A free piston-side, annular projection is formed on an outer periphery of the free piston. The axially opposite surfaces of the free-piston-side annular projection form the free-piston contact surface. Housing-side annular projections, which represent the housing contact surface, are provided on the opposite sides of the annular projection of the inner circumference of the housing. The elastic bodies are provided between the ring-shaped projection on the free piston side and the ring-shaped projection on the housing side or between the ring-shaped projection on the free piston side and the other ring-shaped projection on the housing side. It is therefore possible to design the elastic bodies identically.

The elastic bodies experience deformation by compression due to the bidirectional movement of the free piston. It is therefore possible to accommodate the bidirectional movement of the free piston by means of a single elastic body.

The elastic body is provided as an O-ring and is arranged to seal between the housing and the free piston. Therefore, it is possible to reduce the number of parts.

The elastic body is attached to the housing or the free piston. Therefore, the number of components is reduced and the handling of the components is simplified.

The elastic body is rolled between the free piston and the housing. Therefore, it is possible to change the damping force more smoothly.

The free piston includes a moving direction deformation portion in which the elastic body undergoes elastic deformation in the moving direction of the free piston at a downstream end within the moving range of the free piston, and a rolling portion in which the elastic body is rolled at a position separated from the downstream end becomes. Therefore, it is possible to change the damping force more smoothly.

The rolling area is partially overlapped at the moving direction deformation area. Therefore, it is possible to change the damping force more smoothly.

Shapes of the free piston contact surface and the housing contact surface are adjusted so that the direction of a segment representing the shortest distance between the free piston contact surface and the housing contact surface changes. Therefore, it is possible to change the damping force more smoothly.

The shock absorber comprises a cylinder in which an operating fluid is enclosed; a piston slidably fitted in the cylinder and dividing an interior of the cylinder into two chambers; a piston rod connected to the piston and extending outside of the cylinder; first and second conduits from which the operating fluid flows out from one of the chambers of the interior of the cylinder due to the movement of the piston; a damping force generating mechanism that is disposed in the first conduit and generates a damping force; a housing in which a flow conduit of at least a portion of the second conduit is formed; a free piston movably disposed in the housing and dividing the second conduit into an upstream side and a downstream side; and one or more elastic bodies disposed between the free piston and the housing. In the shock absorber, the free piston includes a moving direction deformation area in which the elastic body experiences elastic deformation in a moving direction of the free piston at a downstream side end within a moving direction of the free piston, and a moving area in which the elastic body is in the moving direction of the free piston in the state in which the elastic body is in contact with both the housing and the free piston at a position separated from the downstream end. Therefore, it is possible to change the damping force more smoothly.

The moving direction is partially overlapped at the moving direction deformation area. Therefore, it is possible to change the damping force more smoothly.

The elastic body is provided in multiple numbers. One of the elastic bodies is deformed at least by compression in the moving direction in the moving direction deformation area, and the other elastic body moves at least in the moving direction of the free piston in the moving direction. Therefore, it is possible to change the damping force more smoothly according to the moving direction of the free piston.

The first line and the second line are formed in the piston. Therefore, it is possible to simplify the structure.

An opening is formed on the upstream side and / or the downstream side of the second conduit. Therefore, it is possible to change the damping force more smoothly.

The shock absorber comprises a cylinder in which an operating fluid is enclosed; a piston slidably fitted in the cylinder and dividing an interior of the cylinder into two chambers; a piston rod connected to the piston and extending outside of the cylinder; first and second conduits from which the operating fluid flows out from one of the chambers of the interior of the cylinder due to the movement of the piston; a damping valve disposed in the first conduit and regulating a flow of the operating fluid generated by the conduit of the piston to generate a damping force; and a free piston movably disposed in the second conduit and dividing the second conduit into an upstream side and a downstream side. A duct area varying mechanism that makes a duct area of the second duct adjustable is disposed in the second duct. This makes it possible to control a damping force characteristic with higher precision.

Furthermore, the second line is formed in the piston rod. The conduction area varying mechanism includes an opening area varying member disposed in the piston rod and an actuator that moves the opening area varying member in a rotary or linear manner. As a result, the line area of the second line can be adjusted by means of a simple and compact structure.

Furthermore, a resistance element, which generates a resistance against the displacement of the free piston, is provided. Therefore, when the damping force is changed in response to the operating frequency of the free piston, it is possible to adjust the damping force uniformly.

Further, since the resistance element is a spring, it is possible to improve durability.

Each of the aforementioned embodiments shows an example in which the present invention is applied to a single-tube hydraulic shock absorber, but it is not limited thereto. The present invention can be used in a two-tube hydraulic shock absorber in which an outer barrel is disposed on the outer periphery of a cylinder and a reservoir is disposed between the outer drum and the cylinder, and can be used in all shock absorbers. Further, in the case of the two-pipe hydraulic shock absorber, a bottom valve connecting between the lower chamber and the reservoir is disposed on the bottom of the cylinder, and the aforesaid housing is disposed on the bottom valve. Thereby, the present invention can be applied to the bottom valve. Further, when an oil passage communicating with the cylinder is disposed on an outside of the cylinder and a damping force generating mechanism is disposed in the oil passage, the aforesaid housing is disposed on the outside of the cylinder. Further, while the embodiments have shown a hydraulic shock absorber by way of example only, water or air can be used as a fluid.

Therefore, in each embodiment, one or two O-rings have been shown purely by way of example. However, if necessary, three or more O-rings can be used based on the same technical idea. Further, while each embodiment shows an example in which a ring made of rubber (resin) is used as an elastic body, a plurality of balls made of rubber may be provided at predetermined intervals in a circumferential direction. Further, the elastic body that can be used in the present invention cannot be made of rubber as long as it has elasticity in a plurality of axial directions instead of the one axial direction.

Further, in the seventh embodiment, the piping area varying mechanism is formed to have openings having four different diameters and changing the piping area in four stages. However, as disclosed in Japanese Unexamined Patent Application First Publication No. H07-077233 disclosed, a wedge-type opening, the diameter of which increases towards one side, can be used. With this structure, since the conduction area is gradually changed, it is possible to adjust the damping force more uniformly.

Claims (10)

Shock absorber comprising: a cylinder (10) in which an operating fluid is enclosed; a piston (11) slidably fitted in the cylinder (10) and configured to divide an interior of the cylinder (11) into two chambers (12, 13); a piston rod (16) connected to the piston (11) and configured to extend out of the cylinder (10); first and second conduits (30a, 30b, 110, 111) from which the operating fluid flows out from one of the chambers (12, 13) of the interior of the cylinder (10) due to the movement of the piston (11); a damping force generating mechanism (32b) which is arranged in the first conduit (30a, 30b) and is configured to generate a damping force; a housing (55) in which a flow line corresponding to at least a portion of the second line (110, 111) is formed; a free piston (57) which is movably arranged in the housing (55) and is designed to divide the second conduit (110, 111) into an upstream side and a downstream side; and one or more elastic bodies (58) which are arranged between the free piston (57) and the housing (55), wherein a free piston contact surface of the free piston (57) with which the elastic body (58) is in contact and / or a housing contact surface of the housing (55) with which the elastic body (58) is in contact comprises an inclined surface which is inclined in a moving direction of the free piston (57), and a shortest distance between a portion in contact with the elastic body (58) within the free piston contact surface and a portion in contact with the elastic body (58) within the Housing contact surface is changed due to the movement of the free piston (57). Shock absorber after Claim 1 wherein the inclined surface of the free piston contact surface and / or the housing contact surface has a curved surface. Shock absorber after Claim 2 wherein the elastic body (58) has a circular cross section and the curved surface of the inclined surface has a radius of curvature larger than a cross sectional radius of the elastic body (58). Shock absorber after Claim 1 , in which the inclined surface is formed by the free piston contact surface and / or the housing contact surface, so that when a shortest distance between a portion that is in contact with the elastic body (58) within the free piston contact surface and a portion that is in contact with the elastic body (58) is within the housing contact surface, becomes smaller, there is an upward inclination. Shock absorber after Claim 1 , in which the free piston contact surface and the housing contact surface have a portion opposite to the direction of movement of the free piston (57). Shock absorber after Claim 1 wherein the elastic bodies (58) comprise an elastic body which is deformed by compression when the free piston (57) moves in one direction, and another elastic body which is deformed by compression when the free piston (57) moves in the other direction. Shock absorber after Claim 1 wherein the elastic body comprises an O-ring and is arranged to seal between the housing (55) and the free piston (57). Shock absorber after Claim 1 in which the elastic body is rolled between the free piston (57) and the housing (55). Shock absorber after Claim 8 , in which the free piston (57) a moving direction deformation area in which the elastic body (59) undergoes an elastic deformation in the moving direction of the free piston (57) at a downstream side end within a moving range of the free piston (57), and a rolling area in which the elastic body is rolled at a position separated from the downstream side end. Shock absorber after Claim 1 , further comprising a conduit area varying mechanism (311) that makes a conduit area of the second conduit (110, 111) adjustable, which is arranged in the second conduit (110, 111).

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