JP2012211650A - Shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a shock absorber which is used as a front fork, a rear cushion unit or the like in a saddle riding vehicle.SOLUTION: The damper 3 stored in a shock absorber body of the shock absorber includes: a cylinder 30; a piston 31 which divides the interior of the cylinder 30 into two working compartments A, B; a rod 32; a sub-tank 33 which is continuously provided on the opposite side of the rod in the cylinder 30; a free piston 35 which divides the interior of the sub-tank 33 into a liquid pool C and an air chamber D, and is biased toward the side of the liquid pool C; a through-hole 6 which is formed in the sub-tank 33 to allow the air chamber D to communicate with a reservoir chamber R. The shock absorber includes: a sealing member 4 which is formed in a circular pattern with elastic properties; a flow passage 5 which is formed in the free piston 35, and allows the liquid pool C to communicate with the air chamber D; and an annular storage groove 50 which is provided halfway through the flow passage 5, and stores the sealing member 4 therein. When the inner pressure of the liquid pool C becomes higher than a predetermined value, the sealing member 4 is deformed so as to blow a working fluid of the liquid pool C into the reservoir chamber R through the flow passage 5.

Description

  The present invention relates to an improvement of a shock absorber used as a front fork, a rear cushion unit, or the like in a saddle-ride vehicle such as a motorcycle.

  Various proposals have been made so far as shock absorbers used as front forks, rear cushion units, etc. in saddle riding vehicles such as motorcycles.

  For example, Patent Document 1 discloses a shock absorber that is used as a front fork, and the front fork suspends a front wheel of a two-wheeled vehicle and absorbs road surface vibration that is input to the front wheel.

The front fork includes a shock absorber body including an outer tube and an inner tube slidably inserted into the outer tube;
A damper housed in the shock absorber main body and a reservoir chamber formed between the damper and the shock absorber main body are provided, and the outer tube is attached to the vehicle body side and the inner tube is attached to the wheel side to be inverted. Is set.

  The damper includes a cylinder suspended from the axial center portion of the outer tube via a sub tank, a piston that is slidably contacted in the cylinder and is partitioned into two working chambers filled with the working fluid, and the piston And a rod that appears and disappears in the cylinder through the shaft and stands at the axial center portion of the inner tube.

  Further, as shown in FIG. 6, the damper is a tangential cylindrical blow piston 401 slidably contacted in the sub tank 330 and urged toward the liquid reservoir chamber C side (lower side in the figure) by the urging rubber 400. The sub-tank 330 is slidably brought into contact with the blow piston 401 and divided into a liquid reservoir chamber C and an air chamber D filled with a working fluid, and attached to the liquid reservoir chamber C side (lower side in the figure) by an urging spring 500. A free piston 501 that is energized, and a base member 34 that divides the working chamber B and the liquid reservoir chamber C on the opposite rod side, and the sub tank 330 has a liquid when the blow piston 401 is retracted by a predetermined amount or more. A communication hole 330a that connects the reservoir chamber C and the reservoir chamber R is formed.

  With the above-described configuration, when the front fork is compressed, the working fluid corresponding to the volume of the rod that has entered the cylinder 30 becomes surplus in the working chamber, and flows out into the liquid reservoir chamber C via the base member 34, and the biasing spring. After the free piston 501 is retracted against the urging force of 500, the blow piston 401 is retracted against the urging force of the urging rubber 400. When the blow piston 401 is retracted by a predetermined amount, the working fluid in the liquid reservoir chamber C is blown into the reservoir chamber R through the communication hole 330a.

JP 2010-230120 A

  In the above-described conventional front fork, the free piston 501 is urged by the urging spring 500 and the blow piston 401 is urged by the urging rubber 400, so that the axial length of the front fork becomes longer, and the parts There is a problem that the score increases.

  Further, as disclosed in FIG. 5 of Patent Document 1, when the blow piston is provided on the free piston, the axial length is shortened but the problem of a large number of parts is not improved, and the blow piston is blown into the free piston. Since the urging spring for urging the piston and the blow piston toward the cylinder is provided, the structure for blowing is complicated.

  Therefore, an object of the present invention is to provide a shock absorber that can reduce the number of parts while shortening the axial length of the shock absorber and can be simply configured to blow.

  Means for solving the above problems are a shock absorber body comprising an outer tube and an inner tube slidably inserted into the outer tube, a damper housed in the shock absorber body, and the damper A reservoir chamber formed between the shock absorber main body, and the damper is a cylinder standing on the axial center of the shock absorber main body, and is in sliding contact with the inner periphery of the cylinder to fill the cylinder with a working fluid. A piston partitioned into two working chambers, a rod protruding and retracting into the cylinder via the piston, a sub tank connected to the opposite side of the cylinder, and a sliding contact with the inner periphery of the sub tank and the interior of the sub tank. A free piston that is divided into a liquid reservoir chamber and an air chamber that are filled with a working fluid and biased toward the liquid reservoir chamber, a base that separates the working chamber on the opposite rod side and the liquid reservoir chamber And a through hole that is formed in the sub tank and communicates the air chamber and the reservoir chamber, and when the internal pressure of the liquid reservoir chamber rises above a predetermined level, the free piston moves backward to In the shock absorber for blowing the working fluid from the through hole to the reservoir chamber, a ring-shaped sealing material having elasticity and a flow path formed in the free piston and communicating the liquid reservoir chamber and the air chamber And an annular housing groove that is provided in the middle of the flow path and accommodates the sealing material, and when the internal pressure of the liquid reservoir chamber is higher than a predetermined level, the sealing material is deformed in the housing groove. In other words, the flow path is communicated.

  According to the present invention, the sealing material has elasticity and opens and closes the flow path formed in the free piston by being deformed according to the internal pressure of the liquid reservoir chamber. There is no need to provide an urging rubber 400 or an urging spring (FIG. 5 of Patent Document 1), and the axial length of the shock absorber is shortened to improve the mountability and the number of parts is reduced. It is possible to simplify the configuration for making it happen.

It is a front view which notches and shows the left half of the front fork which is a buffer in one embodiment of this invention. It is a longitudinal cross-sectional view which expands and shows the principal part of the front fork which is a buffer in one embodiment of this invention. It is a longitudinal cross-sectional view which expands and shows the principal part of the front fork which is a buffer in one embodiment of the present invention, and shows the maximum extension time of the front fork on the left side (a) from the center line. b) shows when the front fork is most compressed. It is a longitudinal cross-sectional view which expands and shows the principal part of the front fork which is a buffer in other embodiment of this invention. It is a perspective view which expands and shows the free piston of the front fork which is a buffer in other embodiments of the present invention, and shows the state where passage of a channel was blocked on the left side (a) rather than the center line rather than the center line The state where the flow path is in communication is shown on the right side (b). It is a longitudinal cross-sectional view which shows the principal part of the front fork which is the conventional shock absorber.

  A shock absorber according to an embodiment of the present invention will be described below with reference to the drawings. The same reference numerals given throughout the several drawings indicate the same or corresponding parts.

  The shock absorber according to the present embodiment is used as a front fork that is interposed between a vehicle body and a front wheel of a two-wheeled vehicle and attenuates road surface vibration input to the front wheel.

  As shown in FIG. 1, the front fork includes a shock absorber body including an outer tube 1 and an inner tube 2 slidably inserted into the outer tube 1, and a damper accommodated in the shock absorber body. 3 and a reservoir chamber R formed between the damper 3 and the shock absorber body.

  The damper 3 includes a cylinder 30 standing on an axial center portion of the shock absorber body, and a piston 31 that is slidably contacted with an inner periphery of the cylinder 30 and is partitioned into two working chambers A and B filled with the working fluid. A rod 32 protruding and retracting into the cylinder 30 through the piston 31; a sub tank 33 provided on the opposite side of the cylinder 30 from the rod side; and a sliding fluid on the inner periphery of the sub tank 33 and working fluid in the sub tank 33. A base member that divides the liquid reservoir chamber C and the air chamber D filled with a free piston 35 energized toward the liquid reservoir chamber C, the working chamber B on the opposite rod side, and the liquid reservoir chamber C. 34 and a through hole 6 formed in the sub tank 33 and communicating the air chamber D and the reservoir chamber R.

  The front fork is configured such that when the internal pressure of the liquid reservoir chamber C rises above a predetermined level, the free piston 35 moves backward to blow the working fluid in the liquid reservoir chamber C from the through hole 6 to the reservoir chamber R. is there.

  Further, the front fork is formed in an annular shape and has an elastic sealing material 4, a flow path 5 formed in the free piston 35 to communicate the liquid reservoir chamber C and the air chamber D, and the flow path 5. And an annular housing groove 50 in which the sealing material 4 is accommodated. In a normal state, the flow path 5 is closed by the sealing material 4, and the internal pressure of the liquid reservoir chamber C is higher than a predetermined value. When the height is increased, the sealing material 4 is deformed in the receiving groove 50 to allow the flow path 5 to communicate.

  Describing in detail below, the front fork according to the present invention is an inverted front fork in which the outer tube 1 is fixed to the vehicle body side and the inner tube 2 is fixed to the wheel side.

  The upper and lower openings of the shock absorber main body composed of the outer tube 1 and the inner tube 2 are a cap member 10 attached to the upper end portion of the outer tube 1 and a bottom member screwed to the outer periphery of the lower end portion of the inner tube 2. 20 and closed respectively.

  In addition, a cylindrical gap formed between the inner periphery of the outer tube 1 and the outer periphery of the inner tube 2 is sealed by a seal member 11 that is attached to the inner periphery of the lower end portion of the outer tube 1 and slidably contacts the outer periphery of the inner tube 2. By providing the above configuration, the working fluid and gas accommodated in the shock absorber main body are prevented from leaking outside.

  An inverted damper 3 is accommodated in the shock absorber main body, and the working fluid is stored in the reservoir chamber R formed between the damper 3 and the shock absorber main body. Gas is compressed while being sealed, and a working fluid chamber R1 is formed below the liquid level O, and a reservoir air chamber R2 is formed above the liquid level O.

  The reservoir air chamber R2 always urges the front fork in the extending direction by its internal pressure and generates a predetermined spring reaction force as the front fork expands and contracts to function as an air spring, and absorbs the thrust input from the road surface. That is, in the present embodiment, the reservoir air chamber R2 serves as a suspension spring, and the internal pressure of the reservoir air chamber R2 can be adjusted by the air valve 10a attached to the cap member 10.

  Further, in the reservoir chamber R, there is provided a balance spring 7 which is compressed when a front fork is extended by a predetermined amount or more to generate a spring reaction force and urges the front fork in the compression direction. When the fork is fully extended, the urging force by the reservoir air chamber R2 is offset.

  That is, when the front fork is extended by a predetermined amount or more, the balance spring 7 urges the front fork in the compression direction against the urging force of the reservoir air chamber R2 to help the front fork contract and improve the ride comfort. It becomes possible to do.

  The inverted damper 3 accommodated in the shock absorber main body includes a cylindrical sub tank 33 suspended from the axial center portion of the outer tube 1 via the cap member 10, and this sub tank 33 is shown in the figure. A sub-tank base end side member that is located on the upper side and is screwed into the inner circumference of the upper end portion of the outer tube 1 and is in close contact with a seal (not shown) and the cap member 10 is screwed into the inner circumference. 33a and a sub tank front end side member 33b that is screwed to the inner periphery of the lower end portion of the sub tank base end side member 33a in the figure.

  Further, the damper 3 is screwed into the inner periphery of the lower end of the sub-tank tip side member 33b in the drawing and is in close contact with the cylinder 30 through a seal (not shown), and two actions that fill the cylinder 30 with working fluid. A piston 31 partitioned into chambers A and B, and a rod 32 protruding and retracting into the cylinder 30 through the piston 31; hereinafter, the working chamber on the rod side is referred to as the extending side working chamber A, and the working chamber on the opposite rod side. It is called a compression side working chamber B.

  The extension side working chamber A and the pressure side action chamber B are not shown, but are connected to each other by an extension side channel and a pressure side channel opened in the piston 31. 31 is closed by the expansion side damping valve V1 stacked on the pressure side working chamber B side, and the pressure side flow path is a pressure side check in which the outlet side opening is stacked on the expansion side working chamber A side of the piston 31. The valve C2 is opened and closed.

  Further, the damper 3 is held by the cap member 10 via the base rod 36 and is fixed to the inner periphery of the cylinder 30 side end portion of the sub tank tip side member 33b. A free piston 35 that slides in contact with the inner periphery of the member 33b and in contact with the outer periphery of the base rod 36 is provided. The free piston 35 partitions the liquid storage chamber C and the air chamber D, and the base member 34 supplies liquid. The reservoir chamber C and the pressure side working chamber B are partitioned.

  Although not shown, the pressure side working chamber B and the liquid reservoir chamber C are communicated by an extension side channel and a pressure side channel drilled in the base member 34, and the extension side channel is based on the outlet side opening. The expansion side check valve C1 stacked on the pressure side working chamber B side of the member 34 is closed so as to be openable and closable, and the pressure side flow path has the outlet side opening stacked on the liquid reservoir chamber C side of the base member 34. The damping valve V2 is closed so that it can be opened and closed.

  The liquid storage chamber C and the air chamber D are communicated with each other via a flow path 5 formed in the free piston 35, and the flow path 5 is an annular accommodation groove 50 provided in the middle of the flow path 5. It is opened and closed by a sealing material 4 made of an O-ring accommodated in

  Since the air chamber D always communicates with the reservoir chamber R through the through hole 6 formed in the sub-tank base end side member 33a, the internal pressure of the air chamber D is the same as the internal pressure of the reservoir air chamber R2. The free piston 35 is urged toward the cylinder 30 by the internal pressure of the air chamber D.

  As shown in FIG. 2, the free piston 35 in which the flow path 5 and the housing groove 50 are formed includes a first small outer diameter portion 50a having an outer periphery formed in a small diameter, and an air flow of the first small outer diameter portion 50a. A second small outer diameter portion 51 having a smaller outer diameter formed on the chamber D side, and a slope portion 50b formed on the air chamber D side of the second small outer diameter portion 51 so that the outer diameter gradually increases. A communication hole 52 that is drilled on the air chamber D side of the free piston 35 and communicates with the inner peripheral portion of the second small outer diameter portion 51, the liquid reservoir chamber C side of the first small outer diameter portion 50a, and the slope. And a pair of large-diameter portions 53, 54 formed on the air chamber D side of the portion 50b and slidably contacting the inner periphery of the sub tank 33 and having grooves 53a, 54a formed along the axial direction.

  The sealing material 4 is fitted to the outer periphery of the first small outer diameter portion 50a to seal between the outer periphery of the first small outer diameter portion 50a and the inner periphery of the sub tank 33, and the internal pressure of the liquid reservoir chamber C is higher than a predetermined value. When it is increased, the sealing material 4 is deformed, and a part of the sealing material 4 is inserted between the outer periphery of the slope portion 50b and the inner periphery of the sub-tank 33, and as shown in FIG. A gap A is formed between the outer periphery of the small outer diameter portion 50a.

  As a result, the working fluid in the liquid storage chamber C flows into the groove 53a, the gap A (FIG. 3 (a)), the outer periphery of the second small outer diameter portion 51 and the inner periphery of the sealing material 4, and the communication hole 52 shown in FIG. And moves into the air chamber D, moves into the reservoir chamber R through the through hole 6 (FIG. 1), and merges with the working fluid in the working fluid chamber R1.

  In other words, in the present embodiment, the fitting portion into which the sealing material 4 is fitted between the outer periphery of the first small outer diameter portion 50a and the inner periphery of the sub tank 33 is formed between the outer periphery of the slope portion 50b and the inner periphery of the sub tank 33. An escape portion into which a part of the seal material 4 is inserted is formed when the seal material 4 is deformed therebetween, and the fitting portion and the relief portion constitute an accommodation groove 50, and the groove 53 a, the accommodation groove 50, The flow path 5 is formed by the communication hole 52 between the outer periphery of the two small outer diameter portions 51 and the inner periphery of the sealing material 4.

  In the present embodiment, an inner peripheral seal 8 composed of an O-ring that seals a gap between the inner periphery of the free piston 35 and the outer periphery of the base rod 36 is provided on the inner periphery of the free piston 35. The stopper S is positioned and fixed on the liquid reservoir C side to prevent the inner peripheral seal 8 from falling off.

  Next, the operation of the front fork in the present embodiment will be described.

  When the front fork is extended in which the inner tube 2 is withdrawn from the outer tube 1 and the rod 32 is withdrawn from the cylinder 30, the extension side working chamber A is pressurized by the piston 31, and the working fluid in the extension side working chamber A is moved to the piston 31. The extension side damping valve V1 stacked on the base member 34 is pushed open to move to the compression side working chamber B, and the extension side check valve C1 stacked on the base member 34 is opened by the working fluid deficient in the cylinder 30 withdrawn from the rod 32. It moves from the liquid reservoir C to the pressure side working chamber B to generate an extension side damping force.

  At this time, since the working fluid in the liquid reservoir C decreases in the sub tank 33, the free piston 35 moves to the cylinder side (lower side in the figure) according to the urging force of the air chamber D having the same pressure as the reservoir air chamber R2. Moving.

  As shown in FIG. 3A, since the sealing material 4 is fitted between the outer periphery of the first small outer diameter portion 50a and the inner periphery of the sub tank 33 (fitting portion), the flow path 5 is The state where communication is blocked by the sealing material 4 is maintained.

  On the other hand, during compression of the front fork in which the inner tube 2 enters the outer tube 1 and the rod 32 enters the cylinder 30, the pressure side working chamber B is pressurized by the piston 31, and the working fluid in the pressure side working chamber B is The pressure side check valve C2 stacked on the piston 31 is opened and moved to the extension side working chamber A, and the pressure side damping valve V2 on which the excess working fluid is stacked in the base member 34 is pushed by the rod 32 entering the cylinder 30. It opens and moves from the pressure side working chamber B to the liquid reservoir chamber C to generate a pressure side damping force.

  At this time, since the working fluid in the liquid reservoir C increases in the sub tank 33, the free piston 35 is opposed to the cylinder side (in the drawing) against the urging force of the air chamber D having the same pressure as the reservoir air chamber R2. Move up).

  As shown in FIG. 3B, the rod 32 further enters the cylinder 30 with the upper surface of the free piston 35 in contact with the base rod holding part 10b of the cap member 10, and the liquid reservoir chamber. When the internal pressure of C rises above a predetermined level, the sealing material 4 is pushed toward the air chamber D by the internal pressure of the liquid reservoir chamber C, and the gap between the outer periphery of the first small outer diameter portion 50a and the inner periphery of the sub tank 33 (the fitting portion). ) Is partly deformed and inserted between the outer periphery of the slope portion 50b and the inner periphery of the sub tank 33 (the escape portion), and the inner periphery of the sealing material 4 and the first small outer diameter portion 50a. A gap A is formed between the outer periphery and the flow path 5 communicates.

  For this reason, the working fluid in the liquid reservoir chamber C is blown to the reservoir chamber R through the flow path 5, the air chamber D and the through hole 6 (FIG. 1), and merges with the working fluid in the working fluid chamber R1.

  Further, when the working fluid in the liquid reservoir chamber C is blown and the internal pressure of the liquid reservoir chamber C becomes a predetermined value or less, the shape of the sealing material 4 is restored to the original, and between the outer periphery of the slope portion 50b and the inner periphery of the sub tank 33. A part of the inserted sealing material 4 comes out, the inner periphery of the sealing material 4 and the outer periphery of the first small outer diameter portion 50a are in close contact with each other, and the communication of the flow path 5 is prevented.

  Therefore, in the present embodiment, the accommodation groove 50 is formed in the middle of the flow path 5 formed in the free piston 35 and communicating the liquid reservoir chamber C and the air chamber D, and is accommodated in the accommodation groove 50. Since the sealing material 4 opens and closes the flow path 5 in accordance with the internal pressure of the liquid reservoir chamber C, the blow piston 401, the urging rubber 400 and the urging rubber that urges the blow piston 401 as in the past (see FIG. 5 of Patent Document 1). ), The mounting length is improved by reducing the axial length of the shock absorber, the number of components is reduced, and the structure for blowing can be simplified.

  Further, a fitting portion (between the outer periphery of the first small outer diameter portion 50a and the inner periphery of the sub tank 33) into which the sealing material 4 is fitted, and a clearance in which a part of the sealing material 4 is inserted when the sealing material 4 is deformed. Since it is composed of a portion (between the outer periphery of the slope portion 50b and the inner periphery of the sub-tank), the flow path 5 can be easily opened and closed using the elastic deformation of the sealing material 4.

  The free piston 35 includes a first small outer diameter portion 50a, a second small outer diameter portion 51, a slope portion 50b, a communication hole 52, and a large outer diameter portion 53 in which a groove 53a is formed. By forming a fitting portion between the outer periphery of the first small outer diameter portion 50a and the inner periphery of the sub tank 33, and forming an escape portion between the outer periphery of the slope portion 50b and the inner periphery of the sub tank 33, the configuration of the housing groove 50 is complicated. Therefore, it is possible to simplify the process.

  Further, since the reservoir air chamber R2 functions as an air spring, the internal pressure of the air chamber D is set to the same pressure as the reservoir air chamber R2, and the free piston 35 is brought to the cylinder 30 side by the internal pressure of the air chamber D. Thus, there is no need to provide a biasing spring 500 for biasing the free piston, the axial length of the shock absorber is further shortened to improve the mountability, and the number of parts is further reduced to reduce the weight of the shock absorber. It becomes possible to do.

  Next, another embodiment of the present invention will be described. In the present embodiment, only the configuration of the flow path in which the housing groove is formed is different from that of the first embodiment, and the other configurations, operations, and effects are the same as those of the first embodiment. Detailed description here is omitted. 1 and 3 are referred to for the same configuration as that of the embodiment.

  In the present embodiment, as shown in FIG. 4, the free piston 35A is formed on the first large inner diameter portion 90a having a large inner circumference and on the air chamber D side of the first large inner diameter portion 90a. The inner diameter of the second large inner diameter portion 91, the slope portion 90b formed on the air chamber D side of the second large inner diameter portion 91 and gradually reducing the inner diameter, and the free piston 35A air. A communication hole 92 that is formed on the chamber D side and communicates with the outer peripheral portion of the second large inner diameter portion 91, and an annular stopper S formed on the liquid reservoir chamber C side of the first large inner diameter portion 90 a. Is provided with a stopper holding portion 93, and a small inner diameter portion 94 formed on the air chamber D side of the slope portion 90b and having a small inner circumference.

  A sealing material 4A made of an O-ring is fitted to the inner periphery of the first large inner diameter portion 90a to seal between the inner periphery of the first large inner diameter portion 90a and the outer periphery of the base rod 36. When the internal pressure increases more than a predetermined value, a part of the sealing material 4A is deformed and inserted between the inner periphery of the slope portion 90b and the outer periphery of the base rod 36, although not shown, the outer periphery of the sealing material 4A and the first large inner diameter portion 90a There is a gap between the circumference.

  As a result, the working fluid in the liquid reservoir C passes between the inner periphery of the stopper S and the outer periphery of the base rod 36, between the gap, the inner periphery of the second large inner diameter portion 91 and the outer periphery of the sealing material 4 </ b> A, and the communication hole 92. Then, it moves to the air chamber D, moves into the reservoir chamber R through the through hole 6 (FIG. 1), and merges with the working fluid in the working fluid chamber R1.

  That is, in the present embodiment, the fitting portion into which the sealing material 4A is fitted between the inner periphery of the large inner diameter portion 90a and the outer periphery of the base rod 36 is between the inner periphery of the slope portion 90b and the outer periphery of the base rod 36. When the seal material 4A is deformed, a relief portion into which a part of the seal material 4A is inserted is formed, and the fitting portion and the relief portion constitute an accommodation groove 90, and the stopper S inner periphery and the base rod 36 outer periphery The flow path 9 is formed by the communication hole 92 between the housing groove 90, the inner periphery of the second large inner diameter portion 91, and the outer periphery of the sealing material 4A.

  In the present embodiment, an annular groove 80 is formed on the outer periphery of the free piston 35A, and an outer periphery seal formed by an O-ring that seals a gap between the outer periphery of the free piston 35A and the inner periphery of the sub tank 33. 8A is fitted.

  Next, the opening / closing operation | movement of the flow path 9 of the front fork in this Embodiment is demonstrated.

  When the front fork is extended, the working fluid in the liquid reservoir chamber C is reduced in the sub-tank 33 as in the embodiment, so that the free piston is applied according to the urging force of the air chamber D having the same pressure as the reservoir air chamber R2. 35A moves to the cylinder side (lower side in the figure).

  As shown in FIG. 4, since the sealing material 4A is fitted between the inner circumference of the first large inner diameter portion 90a and the outer circumference of the base rod 36 (fitting portion), the flow path 9 is formed of the sealing material 4A. Thus, the communication is maintained in a blocked state.

  On the other hand, when the front fork is compressed, the working fluid in the liquid reservoir chamber C increases in the sub tank 33 as in the embodiment, and therefore, the biasing force of the air chamber D having the same pressure as the reservoir air chamber R2 is increased. The free piston 35A moves against the cylinder side (upper side in the figure).

  Although not shown, the rod 32 further enters the cylinder 30 with the upper surface of the free piston 35A in the drawing in contact with the base rod holding portion 10b (FIG. 3) of the cap member 10, and the liquid chamber C When the internal pressure rises above a predetermined level, the sealing material 4A is pushed toward the air chamber D by the internal pressure of the liquid reservoir chamber C, and between the inner periphery of the first large inner diameter portion 90a and the outer periphery of the base rod 36 (fitting portion). A part of the fitted sealing material 4A is inserted between the inner periphery of the slope portion 90b and the outer periphery of the base rod 36 (the escape portion), and between the outer periphery of the sealing material 4A and the inner periphery of the first large inner diameter portion 90a. A gap is formed and the flow path 9 communicates.

  For this reason, the working fluid in the liquid reservoir C is blown to the reservoir chamber R through the flow path 9, the air chamber D and the through hole 6 (FIG. 1), and merges with the working fluid in the working fluid chamber R <b> 1.

  Further, when the internal pressure of the liquid reservoir chamber C becomes a predetermined value or less by blowing the working fluid in the liquid reservoir chamber C, the shape of the sealing material 4A is restored to the original, and between the inner periphery of the slope portion 90b and the outer periphery of the base rod 36. A part of the sealing material 4A inserted into the sealing member 4A comes out, the outer periphery of the sealing material 4A and the inner periphery of the first large inner diameter portion 90a are in close contact with each other, and the communication of the flow path 9 is prevented.

  Therefore, also in the present embodiment, the storage groove 90 is formed in the middle of the flow path 9 that is formed in the free piston 35A and communicates between the liquid reservoir chamber C and the air chamber D, as in the first embodiment. Since the sealing material 4A accommodated in the accommodation groove 90 opens and closes the flow path 9 in accordance with the internal pressure of the liquid reservoir chamber C, the blow piston 401, the urging rubber 400 urging the urging rubber 400 and the urging force are urged. There is no need to provide rubber (FIG. 5 of Patent Document 1), it is possible to shorten the axial length of the shock absorber to improve the mountability, reduce the number of parts, and simplify the structure for blowing. It becomes.

  Further, a fitting portion (between the inner circumference of the first large inner diameter portion 90a and the outer circumference of the base rod 36) into which the sealing material 4A is fitted, and a clearance in which a part of the sealing material 4A is inserted when the sealing material 4A is deformed. Since it is composed of a portion (between the inner periphery of the slope portion 90b and the outer periphery of the base rod 36), the flow path 9 can be reliably opened and closed using the elastic deformation of the sealing material 4A.

  Further, the free piston 35A includes a first large inner diameter portion 90a, a second large inner diameter portion 91, a slope portion 90b, a communication hole 92, and a clearance between the stopper S inner periphery and the base rod 36 outer periphery, By forming a fitting portion between the inner periphery of the large inner diameter portion 90a and the outer periphery of the base rod 36, and forming a slope portion between the inner periphery of the slope portion 90b and the outer periphery of the base rod 36, the configuration of the housing groove 90 is complicated. This makes it possible to simplify the operation.

  Although preferred embodiments of the present invention have been described in detail above, it should be understood that modifications, variations and changes may be made without departing from the scope of the claims.

  For example, the configuration of the housing grooves 50 and 90 is not limited to the above, and for example, as shown in FIG. 5, the housing groove 350 is formed with an annular fitting portion 350a formed on the outer periphery of the free piston 35B. It may be composed of a relief portion 350b formed by partially notching the upper portion of the portion 350 in the drawing.

  In this case, the flow path 351 is formed in the outer periphery of the free piston 35B in the axial direction from the liquid reservoir side end (lower end in the figure) to the fitting portion 350a, and in the radial direction from the fitting portion 350a. And a shaft hole 351c drilled from the air chamber side (upper side in the figure) of the free piston 35B and communicating with the inner end of the diameter hole 35b.

  When the internal pressure of the liquid reservoir C (FIG. 1) is below a predetermined level, as shown in FIG. 5 (a), the groove 351a and the diameter hole 351b are closed with a sealing material 4B made of an O-ring to communicate the flow path 351. When the internal pressure of the liquid reservoir chamber C (FIG. 1) is higher than a predetermined level, as shown in FIG. 5 (b), a part of the sealing material 4B facing the escape portion 350b is curved to form the grooves 351a and The diameter hole 351b communicates, and thereby the flow path 351 can be communicated.

  In the above embodiment, the reservoir air chamber R2 functions as an air spring, the internal pressure of the reservoir air chamber R2 and the internal pressure of the air chamber D are set to the same pressure, and the free pistons 35A and 35B are liquidated with the internal pressure of the air chamber D. However, the present invention is not limited to this, and the free pistons 35 </ b> A and 35 </ b> B may be energized with an energizing spring made of a coil spring or the like as in the prior art.

  Further, in the above embodiment, the sealing materials 4, 4 </ b> A, 4 </ b> B are made of O-rings, but this is not a limitation, and between the free piston outer periphery and the sub tank inner periphery or between the free piston inner periphery and the base rod outer periphery. It is possible to select a configuration as long as it can be sealed, has elasticity, changes its shape upon receiving the internal pressure of the liquid reservoir, and can return to its original shape.

  In the above embodiment, the shock absorber is used as a front fork. However, the present invention is not limited to this, and the shock absorber may be used as a rear cushion unit or other suspension device.

A Stretching side working chamber B Pressure side working chamber C Liquid reservoir chamber D Air chamber R Reservoir chamber R1 Working fluid chamber R2 Reservoir air chamber S Stopper 1 Outer tube 2 Inner tube 3 Damper 4, 4A, 4B Seal material 5, 9, 351 Flow Path 6 Through hole 7 Balance spring 8 Inner circumference seal 8A Outer circumference seal 10 Cap member 20 Bottom member 30 Cylinder 31 Piston 32 Piston rod 33 Sub tank 33a Sub tank base end member 33b Sub tank front end member 34 Base members 35, 35A, 35B Free piston 36 Base rod 50, 90, 350 Housing groove 50a First small outer diameter part 50b, 90b Slope part 51 Second small outer diameter part 52, 92 Communication hole 53, 54 Large outer diameter part 53a, 54a, 351a Groove 90a First Large inner diameter 91 Second large inner diameter

Claims (6)

A shock absorber body comprising an outer tube and an inner tube slidably inserted into the outer tube, a damper housed in the shock absorber body, and formed between the damper and the shock absorber body. And a reservoir chamber
The damper includes a cylinder that stands on the axial center of the shock absorber body, a piston that is slidably contacted with the inner periphery of the cylinder and is partitioned into two working chambers that are filled with the working fluid, and the piston is configured to pass the piston through the piston. A rod that extends and retracts in the cylinder, a sub tank connected to the cylinder on the opposite side of the cylinder, a liquid tank that is in sliding contact with the inner periphery of the sub tank and filled with the working fluid and an air chamber are divided into liquids. A free piston urged toward the reservoir chamber, a base member that partitions the anti-rod-side working chamber and the liquid reservoir chamber, and a through hole formed in the sub-tank to communicate the air chamber and the reservoir chamber And
In the shock absorber that the free piston moves backward when the internal pressure of the liquid reservoir chamber increases above a predetermined value and blows the working fluid in the liquid reservoir chamber from the through hole to the reservoir chamber,
An annularly formed sealing material having elasticity, a flow path formed in the free piston and communicating with the liquid storage chamber and the air chamber, and provided in the middle of the flow path to accommodate the sealing material An annular receiving groove
The shock absorber according to claim 1, wherein when the internal pressure of the liquid reservoir chamber is higher than a predetermined value, the sealing material is deformed in the housing groove and communicates with the flow path.   The housing groove is formed on the liquid reservoir side and includes a fitting portion into which the sealing material is fitted, and a relief portion into which a part of the sealing material is inserted when the sealing material is deformed. The shock absorber according to claim 1. The free piston has a first small outer diameter portion whose outer periphery is formed with a small diameter, a second small outer diameter portion which is formed on the air chamber side of the first small outer diameter portion and has a smaller outer periphery, A slope portion that is formed on the air chamber side of the two small outer diameter portions and the outer periphery gradually increases in diameter, and is formed on the air chamber side of the free piston and communicates with the inner peripheral portion of the second small outer diameter portion. A communication hole, and a pair of large outer diameter portions formed on the liquid chamber side of the first chapter geigaku and the air chamber side of the slope portion, in sliding contact with the inner periphery of the sub tank and having grooves formed along the axial direction. With
The fitting portion is formed between the outer periphery of the first small outer diameter portion and the inner periphery of the sub tank, and the escape portion is formed between the outer periphery of the slope portion and the inner periphery of the sub tank, and is formed on the liquid chamber side. The flow path is constituted by the groove, the receiving groove, the outer periphery of the second small outer diameter portion 51 and the inner periphery of the sealing material, and the communication hole.
When the internal pressure of the liquid reservoir increases more than a predetermined value, the seal material is deformed, and a part of the seal material is inserted into the escape portion, and the inner periphery of the seal material and the outer periphery of the first small outer diameter portion The shock absorber according to claim 2, wherein a gap is created between the flow paths to communicate with the flow path.   The base member is held by a base rod, and the free piston is formed in an annular shape so that the outer periphery of the free piston slides on the inner periphery of the sub tank and the inner periphery of the free piston slides on the outer periphery of the base rod. The shock absorber according to any one of claims 1 to 3, wherein: A first large inner diameter portion having a large inner diameter on the free piston, a second large inner diameter portion formed on the air chamber side of the first large inner diameter portion, and having a larger inner diameter; A slope portion that is formed on the air chamber side of the second large inner diameter portion and whose inner circumference gradually contracts, and a communication that is formed on the air chamber side of the free piston and communicates with the outer peripheral portion of the second large inner diameter portion A hole, a stopper holding portion that is formed on the liquid reservoir chamber side of the first large inner diameter portion and an annular stopper is positioned on the inner periphery, and an inner periphery that is formed on the air chamber side of the slope portion and has a small inner periphery. A small inner diameter portion,
The fitting portion is formed between the inner periphery of the large inner diameter portion and the outer periphery of the base rod, the escape portion is formed between the inner periphery of the slope portion and the outer periphery of the base rod, and the inner periphery of the stopper and the base rod Between the outer periphery, the housing groove, between the inner periphery of the second large inner diameter portion and the outer periphery of the sealing material, and configure the flow path with the communication path,
When the internal pressure of the liquid reservoir increases more than a predetermined value, the sealing material is deformed, and a part of the sealing material is inserted into the escape portion, and between the outer periphery of the sealing material and the inner periphery of the first large inner diameter portion. The shock absorber according to claim 4, wherein a gap is generated to communicate the flow path.   The reservoir chamber includes a working fluid chamber in which working fluid is stored and a reservoir air chamber in which gas is stored while being compressed, and the internal pressure of the reservoir air chamber acts on the free piston via the air chamber. The shock absorber according to any one of claims 1 to 5, wherein the free piston is urged toward the liquid reservoir.

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