JP2009024726A - Pneumatic shock absorber - Google Patents

Abstract

A pneumatic shock absorber having a compression side damping force generating structure capable of setting a compression ratio in a simple configuration, particularly in a low speed region of a piston speed, to approximately 1: 1.
A communication passage having a bottom check valve that allows only a flow from the piston side chamber to the reservoir chamber and a communication path that communicates the piston side chamber and the reservoir chamber in the cylinder, and the reservoir described above. And connecting passages 19 and 20 each having a head-side check valve 20a that allows only a flow from the reservoir chamber to the rod-side chamber, and a lubricating oil O in the piston-side chamber and the reservoir chamber. In the pneumatic shock absorber 1 in which the working gas G is sealed in the cylinder, a cracking pressure adding member 34 is provided on the bottom check valve.
[Selection] Figure 1

Description

  The present invention relates to a pneumatic shock absorber, and more particularly to an improvement in the structure of a compression side damping force generating portion of a pneumatic shock absorber that can be used in a vehicle suspension device such as an automobile or an industrial vehicle.

  Conventionally, as this kind of pneumatic shock absorber, those of various structures can be exemplified, but as the pneumatic shock absorber used in a vehicle suspension device, the one shown in Patent Document 1 is exemplified. Can do.

  That is, as shown in FIG. 5, the upper and lower ends of the cylindrical cylinder 42 are closed by the head member 43 and the bottom member 44, respectively, and are slidably inserted into the cylinder 42 by the piston 45. The cylinder 42 is partitioned into a rod side chamber 40 and a piston side chamber 50.

  The head member 43 is formed in an annular shape, and has a bearing 46 that pivotally supports the piston rod 51 and an accumulation recess 47 that opens from the upper end side.

  The cylinder 42 is covered with a bottomed cylindrical outer cylinder 41 disposed outside the cylinder 42, and an annular seal is formed on the inner peripheral side at the opening end which is the upper end of the outer cylinder 41 in the figure. A sealing member 49 that holds 48 is fixed in a state of being stacked on the head member 43.

  The lower end of the annular seal 48 protruding from the sealing member 49 is disposed in the storage recess 47 of the head member 43, and the oil storage chamber S is formed by the storage recess 47, the sealing member 49, and the piston rod 51. Is defined.

  The piston rod 51 protruding from the cylinder 42 is slidably inserted into the bearing 46 of the head member 43 on the inner peripheral side of the annular seal 48, and the annular seal 48 is slid by a predetermined compression force. It is press-contacted to the outer peripheral surface.

  Therefore, the piston rod 51 passes through the oil storage chamber S, and this oil storage chamber S faces the sliding portion between the piston rod 51 and the annular seal 48.

  Further, the oil storage chamber S is communicated with the rod side chamber 40 by a rod side passage 52 provided in the head member 43, and is communicated with the inside of the reservoir chamber R by another reservoir side passage 53.

  The piston 45 is formed with a pressure side communication passage 45a and an extension side communication passage 45b that communicate the rod side chamber 40 and the piston side chamber 50, respectively.

  The pressure side communication passage 45a is provided with a pressure side damping valve 56 and a pressure side check valve 56a that allows only the flow of gas G and lubricating oil O from the piston side chamber 50 to the rod side chamber 40. The side communication passage 45b is provided with an extension side damping valve 57 and an extension side check valve 57a that allows only the flow of gas G and lubricating oil O from the rod side chamber 40 toward the piston side chamber 50.

  The extension side damping valve 57 and the pressure side damping valve 56 shown in Patent Document 1 are specifically formed of leaf valves that also function as the pressure side check valve 56a and the extension side check valve 57a. .

  The bottom member 44 is provided with a passage 54 that allows the piston side chamber 50 and the reservoir chamber R to communicate with each other. A check valve 55 that allows only a flow from the piston side chamber 50 to the reservoir chamber R is provided in the middle of the passage 54. Is provided.

  The cylinder 42 is filled with a gas G as a working gas, and the oil storage chamber S and the reservoir chamber R are filled with lubricating oil O. The oil level in the oil storage chamber S is the oil storage chamber. In consideration of the fact that the gas G pressure in S and the gas G pressure in the reservoir chamber R do not drop below the lowermost end of the annular seal 48, a sufficient amount of lubricating oil is contained in the reservoir chamber R. O is filled.

  A small amount of lubricating oil O is also injected into the rod-side chamber 40 and the piston-side chamber 50. The lubricating oil O injected into the rod-side chamber 40 is a cylinder when the pneumatic shock absorber starts to expand and contract. The lubricating oil O in the piston side chamber 50 is supplied before the gas G into the reservoir chamber R when the pneumatic shock absorber is contracted, so that the oil storage chamber is provided. This is to prevent the oil level in S from descending.

  In the pneumatic shock absorber configured as described above, the piston rod 45 is retracted from the cylinder 42, that is, the gas G enclosed in the rod side chamber 40 is provided in the piston 45 during the extension stroke of the pneumatic shock absorber. The expansion side communication passage 45b passes through the piston side chamber 50 and the expansion side damping valve 57 provided in the expansion side communication passage 45b generates an expansion side damping force.

  Further, the piston rod 45 enters the cylinder 42, that is, in the pressure side stroke of the pneumatic shock absorber, the gas G sealed in the piston side chamber 50 passes through the pressure side communication passage 45a provided in the piston 45 and passes through the rod side chamber. The pressure side damping force is generated by the pressure side damping valve 56 provided in the pressure side communication passage 45a.

  At this time, due to the pressure increase in the piston side chamber 50, the gas G in the piston side chamber 50 also flows into the reservoir chamber R through the passage 54 with the check valve 55, and at the same time, the lubricating oil O heavier than the gas G is also generated. It flows into the reservoir chamber R together with the gas G.

  Then, since the reservoir chamber R and the oil storage chamber S are pressurized in the same manner as the piston-side 50 chamber, the lubricating oil O in the reservoir chamber R flows into the oil storage chamber S, and the pressure in the oil storage chamber S is increased. And raise the oil level.

Next, the gas G and the lubricating oil O pass through the rod side passage 52 and flow into the rod side chamber 40 due to the rise in the oil level and the pressure increase in the oil storage chamber S, and the lubricating oil O in the pneumatic shock absorber. Will circulate.
JP 2007-16880 A (Fig. 2 and paragraph numbers ~)

  However, in the pneumatic shock absorber configured as described above, a passage 54 with a check valve 55 that communicates the piston side chamber 50 and the reservoir chamber R is provided in the bottom member 44 in order to circulate the lubricating oil O. Therefore, in the pressure side stroke, the check valve 55 opens due to an increase in the internal pressure.

  For this reason, in the compression side stroke, the pressure in the piston side chamber 50 is not as high as that in the rod side chamber 40 in the expansion stroke, and the generated compression side damping force cannot be as high as the expansion side damping force.

  By the way, as a shock absorber attached to a suspension device of an automobile, in recent years, many have a damping force characteristic as shown in FIG. 6 in order to improve riding comfort and maneuverability.

  That is, in the low speed region of the piston speed (0.2 m / sec or less), for example, at 0.1 m / sec, as shown by the straight line L, the generated damping force is high and rises linearly, and the piston speed exceeding that is In the high speed range, as indicated by the straight line M, the damping force characteristic (hereinafter referred to as saturation characteristic) is set so that the generated damping force is substantially constant.

  Therefore, when the damping force generating structure for realizing this saturation characteristic is provided in the piston 45, the pneumatic shock absorber having the above configuration is provided in the bottom member 44 even in the low speed region where the pressure in the piston side chamber 50 is low in the pressure side stroke. Further, since the check valve 55 is opened, there is a problem that the pressure increasing ratio in the low speed region cannot be set to about 1: 1.

  That is, in the pressure side stroke, the presence of the passage 54 with the check valve 55 prevents the internal pressure of the piston side chamber 50 from becoming as high as that in the rod side chamber 40 in the extension side stroke. It will be lower overall.

  Accordingly, an object of the present invention is to provide a pneumatic shock absorber having a compression side damping force generation structure that can set the compression ratio in a low speed region of the piston speed to be substantially 1: 1 with a simple configuration. is there.

  In order to achieve the above object, the present invention provides a bottomed cylindrical outer cylinder, a cylinder disposed inside the outer cylinder, a reservoir chamber formed between the cylinder and the outer cylinder, A piston that divides the rod side chamber and the piston side chamber, a piston rod that is movably inserted into the cylinder via the piston, a passage provided in the piston for communicating the rod side chamber and the piston side chamber, and this passage A damping force generating portion provided in the piston side chamber and the reservoir chamber, and a communication path including a bottom side check valve that allows only a flow from the piston side chamber to the reservoir chamber, and the reservoir chamber and A rod-side chamber, and a connection path having a head-side check valve that allows only a flow from the reservoir chamber to the rod-side chamber, the piston-side chamber, With injecting lubricant observers chamber, the pneumatic shock absorber enclosing the working gas in the cylinder, provided with a cracking pressure addition member to the bottom side check valve.

  According to the pneumatic shock absorber of the present invention, the bottom side check valve is provided with a cracking pressure addition member, and the bottom side reverse valve is operated in a specific speed range such as a low speed range of the piston speed in the pressure side stroke. The stop valve can be prevented from opening.

  Accordingly, in the speed range where the bottom side check valve does not open, the generated compression side damping force can be controlled by the damping force generating portion provided in the piston, and the pressure expansion ratio in this speed range can be set to approximately 1: 1. .

  Hereinafter, an embodiment in which the valve structure of the present invention is embodied in a pneumatic shock absorber used in an automobile suspension device will be described with reference to the drawings.

  As shown in FIG. 1, the pneumatic shock absorber 1 of the present embodiment includes a bottomed cylindrical outer cylinder 2, a cylinder 3 disposed concentrically inside the outer cylinder 2, A reservoir chamber R formed between the outer cylinders 2, a piston 5 that divides the inside of the cylinder 3 into a rod side chamber 40 and a piston side chamber 50, and the rod 5 for connecting the rod side chamber 40 and the piston side chamber 50 are provided in the piston 5. The reservoir chamber R and the piston side chamber 50 communicate with each other, the damping force generating portion provided in the passage, the piston rod 6 movably inserted into the cylinder 3 via the piston 5, and the piston The communication passage 9 having a bottom check valve that allows only the flow from the side chamber 50 to the rod side chamber 40, the cracking pressure applying member of the present invention provided in the bottom check valve, and the reservoir chamber And a connecting passage having a head-side check valve that allows only flow from the reservoir chamber R to the rod-side chamber 40, and connects the rod-side chamber 40, the piston-side chamber 50, and the reservoir chamber R. Oil O is injected and a gas G as working gas is enclosed in the cylinder 3.

  More specifically, a rod guide 12 as a head member for guiding the piston rod 6 is provided at the opening end portion of the cylinder 3 which is the inner periphery of the upper end portion of the outer cylinder 2. A main seal 13 as a sealing member is placed.

  The outer cylinder 2, the main seal 13, the rod guide 12 and the cylinder 3 are integrally crimped and fixed by bending the upper end of the outer cylinder 2 inward.

  The rod guide 12 is formed in a columnar shape having a guide hole 17 to which a bearing 12a as a bearing is attached at the center, and the inner peripheral surface of the bearing 12a is in sliding contact with the outer peripheral surface of the piston rod. A piston rod 6 is slidably supported by a bearing, and a storage recess 18 for storing lubricating oil O is formed at the center of the upper surface.

  The storage recess 18 defines an oil storage chamber S with the storage recess 18 and the main seal 13, and the storage recess 18 is connected to the reservoir chamber side connection path 19 communicating with the reservoir chamber R and the rod side chamber 40. The rod chamber side connection path 20 with the check valve 20 a that communicates is connected, and the lubricating oil O of the reservoir chamber R is temporarily stored in the oil storage chamber S, and then the rod side chamber 40 via the rod chamber side connection path 20. To come out.

  The reservoir chamber side connection path 19 and the rod chamber side connection path 20 constitute the connection path of the present invention.

  The main seal 13 includes an annular insert metal 14 and an inner peripheral lip 15 as an annular seal integrally formed on the inner peripheral side of the insert metal 14.

  The inner peripheral lip 15 is formed in a so-called triple lip structure, and in the same order as the dust lip 15a that slides in contact with the outer peripheral surface of the piston rod 6 in order from the atmosphere side to prevent dust from entering from the atmosphere side. An oil lip 15b that slides on the outer peripheral surface of the piston rod 6 and prevents the lubricating oil O from the oil storage chamber S from leaking to the atmosphere together with the gas G enclosed in the cylinder 3, and the outer peripheral surface of the piston rod 6 as well. A shutoff lip 16 that prevents the lubricating oil O from the oil storage chamber S from leaking to the rod side chamber 40 side together with the gas G is integrally formed.

  The blocking lip 16 includes a base portion 16b formed integrally with the inner peripheral lip 15, and a lip portion 16a that is formed integrally with the base portion 16b and extends toward the piston rod 6, and the lower surface of the lip portion 16a. Is in pressure contact with the peripheral edge of the guide hole 17 of the rod guide 6 so that the lubricating oil O in the oil storage chamber S does not leak into the rod side chamber 40 through the pressure contact portion.

  An oil reservoir chamber 28 having a substantially isosceles trapezoidal cross section is formed between the shutoff lip 16 and the oil lip 15b between the outer peripheral surface of the piston rod 6 and the oil reservoir is formed in the base portion 16b. A plurality of communication holes 16c for communicating the chamber 28 and the oil storage chamber S are provided.

  The lip portion 16a is formed in a lip shape so that the lubricating oil O adhering to the piston rod 6 is scraped into the oil reservoir chamber 28 when the piston rod 6 is operated, and the lip portion 16a is When the pressure difference between both sides, that is, in the oil storage chamber S and in the oil reservoir chamber 28, and the rod side chamber 40 becomes larger than a predetermined value, the lubricating oil O from the oil storage chamber S and the oil reservoir chamber 28 is elastically deformed. The rod guide 12 and the piston rod 6 are designed to flow to the rod side chamber 40 through a gap.

  Further, the lubricating oil O is stored in the oil storage chamber S up to a position where the base portion 16b of the shut-off lip 16 is immersed, and the lubricating oil O is guided to the oil reservoir chamber 28 through the communication hole 16c. The lubricating oil O stored in the chamber 28 prevents oil film breakage between the inner peripheral lip 15 and the piston rod 6. When the internal pressure in the oil storage chamber S is increased by the pressure stroke of the pneumatic shock absorber 1, the lower surface of the lip portion 16a of the blocking lip 16 is brought into pressure contact with the peripheral edge of the guide hole 17 of the rod guide 12 by the internal pressure. The sealing performance of the pressure contact portion is further improved.

  Further, the connecting position of the rod chamber side connection path 20 with respect to the storage recess 18 is more than that of the communication hole 16c so that excess lubricating oil O accumulated above the communication hole 16c of the blocking lip 16 flows into the rod side chamber 40. Is also set at the upper position.

  The piston 5 is fixedly attached to the lower end of the piston rod 6, and a piston ring (not shown) that is in sliding contact with the inner peripheral surface of the cylinder 3 is fitted on the outer periphery of the piston 5.

  The piston 5 communicates with the rod side chamber 40 and the piston side chamber 50, and a plurality of pressure side communication passages (only one is shown in FIG. 1) 21 arranged on the same circumference and the pressure side communication passage 21 are the same. A plurality of extension side communication passages (only one is shown in FIG. 1) 22 arranged alternately on the circumference are formed toward the lower surface.

  In the middle of the extension side communication passage 22, an extension side check valve 22a that allows only a flow from the rod side 40 chamber to the piston side 50 chamber is provided, and a damping force is generated above the extension side check valve 22a. An expansion side variable throttle 22b as a part is provided, and a pressure side check valve 21a that allows only a flow from the piston side chamber 50 to the rod side chamber 40 is provided in the middle of the pressure side communication passage 21, and this pressure side check valve A pressure side variable throttle 21b as a damping force generator is also provided below 21a.

  An annular wall 23 is provided on the upper surface of the piston 5 so as to rise from the upper surface and face the cylinder 3 via an annular gap P. Lubricating oil O is placed in the gap P and the annular wall 23. You can save it.

  A valve case 31 is provided at the lower end of the cylinder 3 as a bottom member having a gate shape in cross section.

  The valve case 31 has a lower end of the cylinder 3 on the upper surface, a cylindrical leg portion 31a whose lower surface is in contact with the bottom of the outer cylinder 2, and a valve body 31b on a disc formed on the upper surface of the leg portion 31a. It is composed of

  The valve body 31b is formed with a plurality of circumferential passages 9 communicating the reservoir chamber R and the piston side chamber 50, and the leg portion 31a has the reservoir chamber R and the piston side chamber 50 connected to each other. A plurality of cutout portions 33 that communicate with each other are formed.

The bottom surface of the valve body 31b is a bottom-side check valve that closes the communication passage 9 so that only the flow of the gas G and the lubricating oil O from the piston-side chamber 50 toward the reservoir chamber R is allowed. A bottom leaf valve 32 is disposed.
The bottom side leaf valve 32 is formed in a disc shape having an insertion hole (not shown) in the center, and the bottom surface of the bottom side leaf valve 32 has a reverse portal shape as a cracking pressure applying member. An initial valve 34 is arranged.

  As shown in FIGS. 2 and 3, the initial valve 34 includes a disc-shaped main body 34a having an insertion hole 34c in the center, and a ring-shaped protrusion formed so as to protrude upward on the outer peripheral portion of the main body 34a. Part 34b, these may be formed integrally, or the main body 34a and the projection 34b are formed as separate members and integrated using a bonding method such as adhesion. May be.

  Then, the fixing bolt 35 inserted from the upper side to the lower side in the central portion of the valve body 31b is inserted into the insertion hole 34c of the bottom side leaf valve 32 and the initial valve 34, and at the lower end side of the fixing bolt 35. By tightening and fixing the nut 36, the initial valve 34 is elastically deformed upward at the central portion thereof, whereby an initial load is applied to the outer peripheral end of the bottom surface of the bottom side leaf valve 34.

  The initial valve 34 is designed to have a shape and rigidity so as to open only when the piston speed reaches, for example, 0.05 m / sec to 0.2 m / sec. The cracking pressure can be set so that the valve 34 opens.

  For example, the pneumatic shock absorber configured as described above attaches a rod-side eye (not shown) provided at the tip of the piston rod 6 to the vehicle body side, and a cylinder-side eye 37 provided at the lower end of the cylinder 3 on the axle side. By installing it, it is built into the suspension system of a car.

  Next, the operation will be described. The piston rod 6 retracts from the inside of the cylinder 3, that is, in the expansion stroke of the pneumatic shock absorber 1, the gas G sealed in the rod side chamber 40 is expanded on the piston 5. While passing through the communication passage 22 and flowing into the piston-side chamber 50, an expansion-side damping force is generated by the expansion-side variable throttle 22 b provided in the middle of the expansion-side communication passage 22.

  Further, when the piston rod 6 enters the cylinder 3, that is, in the pressure side stroke of the pneumatic shock absorber 1, the gas G sealed in the piston side chamber 50 passes through the pressure side communication passage 21 provided in the piston 5 and the rod. While flowing into the side chamber 40, a pressure side damping force is generated by the pressure side variable throttle 21b provided in the middle of the pressure side communication passage 21.

  At this time, the bottom side leaf valve 32 is placed on the lower surface of the valve body 31b, and the initial valve 34 is disposed on the lower surface thereof, and an initial load is applied to the bottom side leaf valve 32. As shown in the conventional example, the bottom-side leaf valve 32 does not open in the low speed range of the low piston speed in the range where the pressure of the piston side chamber 50 is set.

  For this reason, in the low speed range where the bottom side leaf valve 32 is not opened, the compression side damping force can be controlled by the compression side variable throttle 21b provided in the piston, so that the compression ratio in the low speed range can be set to be substantially one to one.

  Further, in the high speed region of the piston speed, for example, 0.1 m / second or more in FIG. 6, the pressure in the piston side chamber 50 becomes higher than the cracking pressure so that the initial load resists the initial load of the bottom side leaf valve 32. The valve 34 is opened, and the lubricating oil O and gas G in the piston side chamber 50 pass through the communication passage 9 and flow into the reservoir chamber R, and then the oil storage via the reservoir chamber side connection path 19 provided in the rod guide 12. Guided to chamber S.

  Then, excess lubricating oil O accumulated in the oil storage chamber S flows out to the rod side chamber 40 through the rod chamber side connection path 20, and adheres to the sliding contact portion between the piston 5 and the cylinder 3, or the above It is stored inside the annular wall 23 provided on the upper surface of the piston 5 or in a gap P between the annular wall 23 and the cylinder 3 to improve slidability and circulation.

  As described above in detail, in the pneumatic shock absorber 1 according to the present embodiment, the bottom side leaf valve 32 reaches the cracking pressure set in the low speed region of the piston speed by the initial load generated by the initial valve 34. Since the valve is not opened, the pressure-side damping force generated in the pressure-side stroke can be controlled by the pressure-side variable restrictor 21b provided in the piston 5, and the pressure increase ratio in this low speed region can be set to approximately 1: 1.

  Accordingly, with the simple configuration in which the initial valve 34 is arranged on the lower surface of the bottom leaf valve 32 and is pressed and urged toward the bottom leaf valve 32, the tension ratio in the low speed region is set to approximately 1: 1. Can do.

  Further, in this pressure side stroke, the bottom side leaf valve 32 opens against the initial load in the high speed region of the piston speed, so that the damping force in this high speed region can be made substantially constant only by the pressure side variable throttle 21b. This can be easily performed compared with the conventional method, and as a result, the saturation characteristic shown in the conventional example can be easily created.

  Further, since the initial valve 34 is composed of a disc-shaped main body 34a having an insertion hole 34c in the center and an annular protrusion 34b formed to protrude upward on the outer periphery of the main body 34a, The structure can be manufactured at low cost.

  Further, even if the initial valve 34 is arranged on the lower surface of the bottom side leaf valve 32, the bottom side leaf valve 32 and the initial valve are connected to the fixing bolt 35 inserted from the upper side to the lower side in the central portion of the valve body 31b. Since 34 has a simple structure in which it is inserted through the insertion holes 34c and fixed by the nut 36, it can be implemented at low cost.

  Further, since the annular wall 23 is provided on the upper surface of the piston 5 so as to rise from the upper surface and face the cylinder 3 via the annular gap P, the lubricating oil O can be stored in the gap P. In the low piston speed range where the bottom leaf valve 32 is not opened, the lubricating oil O in the gap P can be used to ensure the slidability between the cylinder 3 and the piston 5.

  Further, the inner peripheral lip 15 is integrally provided with a blocking lip 16 comprising a base portion 16b formed integrally with the inner peripheral lip 15 and a lip portion 16a formed integrally with the base portion 16b and extending toward the piston rod 6. At the same time, the lower surface of the lip portion 16a is pressed against the periphery of the guide hole 17 of the rod guide 6 so that the lubricating oil O in the oil storage chamber S does not pass through the pressure contact portion and leak into the rod side chamber 40. In addition, since the oil reservoir chamber 28 is formed between the shutoff lip 16 and the oil lip 15b, and the oil reservoir chamber 28 is communicated with the oil storage chamber S, the pressure side variable throttle 21b is not opened. In the low speed region of the piston speed, the lubricating oil O in the oil storage chamber S can be used to ensure the slidability between the inner peripheral lip 15 and the piston rod 6, and the Rurippu 15b directly, so can be prevented from coming into contact with the gas G, the leakage to the atmosphere side of the gas G as described above can be reliably prevented.

  Further, when the internal pressure in the oil storage chamber S increases in the pressure side stroke of the pneumatic shock absorber 1, the internal pressure is transmitted to the lip portion 16a of the shut-off lip 16 via the oil reservoir chamber 28, and this lip portion 16a is Since the lip portion 16a is deformed downward, the lower surface of the lip portion 16a comes into pressure contact with the peripheral portion of the guide hole 17 of the rod guide 12, and the sealing performance of the pressure contact portion can be further improved.

  Next, another embodiment of the present invention will be described.

  This other embodiment is different from the above embodiment only in that the definition structure of the oil storage chamber S is different from the specific configuration of the bottom side leaf valve 32 and the initial valve 34 provided in the valve case 31. Is different.

  That is, as shown in FIG. 4, a mounting recess 12b is provided on the inner periphery of a bearing 12a provided at the center of the rod guide 12, and a seal ring 11 as a seal member is mounted in the mounting recess 12b. The ring 11 is brought into sliding contact with the piston rod 6.

  At this time, the oil storage chamber S is defined by the main seal 13, the piston rod 6, and the seal ring 11 by making the structure of the main seal 13 the structure shown in the conventional example.

  An annular valve-side protrusion 32c is formed on the outer periphery of the bottom-side leaf valve 32 placed on the bottom surface of the valve case 31 so as to protrude downward. An initial valve 39 having a disk shape is placed on the base plate, and the nut 36 is tightened to apply an initial load to the outer peripheral end of the bottom surface of the bottom leaf valve 32 as in the above embodiment.

  Therefore, the other embodiments exhibit the same operations and effects as the above-described embodiments, and according to the defined structure of the oil storage chamber S, the main seal 13 is used for a normal shock absorber or the like. Therefore, it can be realized at a low cost.

  In addition, this invention is not limited to the said embodiment, For example, it can also be changed as follows.

(1) In the present embodiment, the pressure side communication hole 21 and the expansion side communication hole 22 are provided with the pressure side variable throttle 21b and the expansion side variable throttle 22, respectively. Any configuration other than the variable aperture can be adopted depending on the characteristics.

(2) In the present embodiment, the protrusions 34b and 32c provided on the initial valve 34 and the bottom leaf valve 32 are integrated with these valves. However, the present invention is not limited to this, and the protrusions 34b, Only 32c may be provided as a separate body and disposed between the initial valve 34 and the bottom leaf valve 32.

  Also. You may make it apply an initial with a spring from the lower surface side of the bottom side leaf valve 32.

(3) In this embodiment, the variable throttle 21b is disposed in the pressure side communication passage 21 of the piston 5. However, if a cracking pressure adding member is provided in the variable throttle 21b, the characteristics of the compression side damping force can be further improved. It can be changed to two stages.

It is sectional drawing of the pneumatic shock absorber which shows one embodiment of this invention. It is a top view which shows an initial valve. It is sectional drawing of the initial valve of FIG. It is sectional drawing of the pneumatic shock absorber which shows other embodiment of this invention. It is sectional drawing of the pneumatic shock absorber which shows a conventional structure. It is a figure which shows the damping-force characteristic of a buffer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pneumatic shock absorber 2 Outer cylinder 3 Cylinder 5 Piston 6 Piston rod 9 Communication path 11 Seal ring (seal member)
12 Rod guide (head member)
12a Bearing
12b Mounting recess 13 Main seal (sealing member)
15 Inner lip (annular seal)
15a Dustrip 15b Oil lip 16 Shut-off lip 18 Storage recess 19 Reservoir chamber side connection path (connection path)
20 Rod chamber side connection path (connection path)
20a Check valve (head side check valve)
21 Pressure side passage (passage)
21b Pressure-side variable throttle 22 Stretch-side communication passage (passage)
22b Stretching side variable throttle 23 Annular wall 31 Valve case (bottom member)
31b Valve body 32 Bottom side valve as bottom side check valve 34, 39 Initial valve (cracking pressure addition member)
35 Fixing bolt 36 Nut 40 Rod side chamber O Lubricating oil R Reservoir chamber S Oil storage chamber G Gas (working gas)

Claims (8)

A bottomed cylindrical outer cylinder, a cylinder disposed inside the outer cylinder, a reservoir chamber formed between the cylinder and the outer cylinder, a piston that divides the cylinder into a rod side chamber and a piston side chamber, A piston rod movably inserted into the cylinder via a piston, a passage provided in the piston for communicating the rod side chamber and the piston side chamber, a damping force generating portion provided in the passage, and the piston side chamber And the communication passage having a bottom check valve that allows only the flow from the piston side chamber to the reservoir chamber, and the reservoir chamber and the rod side chamber, and the reservoir chamber to the rod side chamber. And a connecting passage having a head-side check valve that allows only flow to the piston, and injecting lubricating oil into the piston-side chamber and the reservoir chamber, In pneumatic damper enclosing a working gas into serial cylinder, pneumatic shock absorber, characterized in that a cracking pressure addition member to the bottom side check valve. The pneumatic shock absorber according to claim 1 or 2, wherein the piston is provided with an annular wall that rises from an upper surface thereof and faces the cylinder via a gap. The cylinder is closed by providing a head member and a bottom member at the upper and lower ends thereof, the head member is formed in an annular shape, and an inner periphery thereof is provided with a bearing for pivotally supporting the piston rod, A storage recess opening from the upper end side is provided, and an oil storage chamber is defined by the storage recess and a sealing member that is placed on the head member and holds an annular seal on the inner peripheral side. The pneumatic shock absorber according to claim 1, which is provided in the middle of the road. The annular seal includes a dust strip that is in sliding contact with the outer peripheral surface of the piston rod to prevent dust from entering from the atmosphere side, and a working gas that is also in sliding contact with the outer peripheral surface of the piston rod and in which the lubricating oil is sealed in the cylinder. The oil lip that prevents leakage to the atmosphere side, and the lower surface abuts against the end of the bearing while slidingly contacting the outer peripheral surface of the piston rod. 4. The pneumatic shock absorber according to claim 3, wherein the pneumatic shock absorber comprises a blocking lip for preventing leakage into the air. The cylinder is closed by providing a head member and a bottom member at the upper and lower ends thereof, the head member is formed in an annular shape, and an inner periphery thereof is provided with a bearing for pivotally supporting the piston rod, A storage recess that opens from the upper end side is provided, and the storage recess, a sealing member that is placed on the head member and holds an annular seal on the inner peripheral side, a seal member provided on the bearing, and the piston rod 2. The pneumatic shock absorber according to claim 1, wherein an oil storage chamber is defined, and the oil storage chamber is provided in the middle of the connection path. The bottom member includes a valve body having the communication passage and a disc-shaped bottom leaf valve mounted on the lower surface of the valve body so as to close the communication hole. The pneumatic shock absorber according to claim 3, further comprising: a cracking pressure applying member disposed on a lower surface of the bottom check valve. The cracking pressure applying member is an initial valve having an inverted cross-sectional shape mounted on the lower surface of the disc-shaped bottom side check valve, and is inserted from the upper side to the lower side at the center of the valve body. 7. The initial valve is elastically deformed upward in the center by tightening and fixing a nut to the fixed bolt, and an initial load is applied to the outer peripheral end of the bottom surface of the bottom check valve. Pneumatic shock absorber as described. The pneumatic shock absorber according to claim 7, wherein a cracking pressure is set so that the initial valve opens when a piston speed becomes 0.05 m / sec to 0.2 m / sec.

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