JP2017166573A - Shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shock absorber capable of preventing immersion of gas into a cylinder even if a gas spring is installed.SOLUTION: This invention comprises a cylinder 1 formed with a working chamber storing liquid therein; a rod 3 movably inserted into the cylinder 1; an air cylinder C connected to the rod 3 and having the cylinder 1 movably inserted inside of it; an annular rod guide 10 connected to the cylinder 1 to support the rod 3 movably to define an inside of the air cylinder C to a first gas chamber G1 at the rod 3 side where gas is fed and a second gas chamber G2 at the cylinder 1 side; a seal 14 for liquid and a seal 13 for gas arranged at an inner periphery of the rod guide 10; a pressure releasing passage 10c at the inner periphery of the rod guide 10 to cause a space K formed between the seal 14 for liquid and the seal 13 for gas to be communicated with the second gas chamber G2; and a check valve 19 arranged at the pressure releasing passage 10c allowing only the flow of liquid going from the space K toward the second gas chamber G2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a shock absorber.

  2. Description of the Related Art Conventionally, some shock absorbers used in straddle-type vehicles such as two-wheeled vehicles or three-wheeled vehicles have a suspension spring replaced with a metal coil spring for the purpose of weight reduction.

  A shock absorber using such a gas spring is connected to, for example, a cylinder, a rod movably inserted into the cylinder, and an end of a rod protruding outward from the cylinder. And a tubular member that forms an air chamber (for example, Patent Document 1). In the shock absorber, high-pressure gas is sealed in the air chamber. When the shock absorber expands and contracts, the air chamber volume is expanded and contracted, and an elastic force corresponding to the degree of expansion and contraction of the shock absorber can be obtained. Also, two chambers defined by pistons are formed in the cylinder of the shock absorber, and each chamber is filled with hydraulic oil. When the shock absorber expands and contracts, the piston compresses one of the chambers and expands the other chamber to generate a differential pressure between the two chambers and exert a damping force.

  Further, the shock absorber includes an annular rod guide that is coupled to the cylinder and pivotally supports the rod, and an oil seal that is in sliding contact with the outer periphery of the rod is provided on the inner periphery of the rod guide. An air seal that is slidably in contact with the outer periphery of the rod is provided on the inner periphery of the guide and closer to the air chamber than the oil seal. According to this configuration, even if the shock absorber contracts and the pressure in the air chamber increases, the air seal can prevent the pressure in the air chamber from acting on the oil seal. Therefore, the oil seal is opened by receiving the pressure in the air chamber, and the gas in the air chamber can be prevented from entering the cylinder.

JP 2001-501155 A, FIGS.

  Here, when the shock absorber with the gas spring is extended, most of the hydraulic oil adhering to the outer periphery of the rod is scraped off by the oil seal when the rod retracts from the cylinder, but the rod that has passed through the oil seal A thin oil film is formed on the outer periphery of the film. When the rod passes through the air seal, a small amount of the oil film adhering to the outer periphery of the rod may be scraped off by the air seal and collected in the space between the air seal and the oil seal. Furthermore, when the shock absorber that the rod enters into the cylinder contracts, if the hydraulic oil in the space is scraped off by the oil seal and left in the space, In some cases, hydraulic oil accumulates in the interior and the pressure in the space becomes high.

  As described above, when the space becomes high pressure due to the accumulation of hydraulic oil, high pressure acts on the air seal that receives pressure from the air chamber side from the space side that is the back surface of the air seal, thereby degrading the sealing performance of the air seal, There is a possibility that gas inside the air chamber may enter the inside. And if gas enters the cylinder, it is not preferable because the response of the damping force generation of the shock absorber is lowered.

  Then, even if it has a gas spring, this invention aims at provision of the buffer which can prevent the penetration | invasion of the gas into a cylinder.

  The invention according to claim 1, which solves the above problem, includes a rod that is movably inserted into a cylinder in which a working chamber in which a liquid is accommodated is formed, and the cylinder that is connected to the rod and is connected to the inside. An air cylinder that is movably inserted, a rod-side first air chamber that is connected to the cylinder and supports the rod movably, and gas is sealed in the air cylinder, and a cylinder-side second chamber An annular rod guide partitioned into an air chamber, a liquid seal and a gas seal provided on the inner periphery of the rod guide, and an inner periphery of the rod guide, the liquid seal and the gas seal A pressure relief passage that communicates a space formed between the second air chamber and a valve that is provided in the pressure relief passage and allows only a liquid flow from the space toward the second air chamber. For this reason, since the pressure can be released from the space to the second air chamber, the inside of the space is prevented from becoming a high pressure, the high pressure acts on the back surface of the gas seal, and the sealing performance of the gas seal is lowered. Can be prevented.

  According to the shock absorber of the present invention, the gas can be prevented from entering the cylinder even if the gas spring is provided.

It is the longitudinal cross-sectional view which showed the buffer which concerns on one embodiment of this invention. It is the figure which expanded a part of FIG.

  Embodiments of the present invention will be described below with reference to the drawings. The same reference numerals used throughout the several drawings indicate the same parts.

  A shock absorber A according to an embodiment of the present invention shown in FIG. 1 is mounted on a straddle-type vehicle such as a two-wheeled vehicle or a three-wheeled vehicle, and is swingably connected to a frame serving as a skeleton of the vehicle body and a rear portion of the frame. The rear cushion unit unit is interposed between the swing arm that supports the rear wheel.

  The shock absorber A includes a cylinder 1, a piston 2 that is slidably inserted into the cylinder 1, a rod 3 having a lower end coupled to the piston 2 in FIG. 1 and an upper end extending outside the cylinder 1, and a diagram of the cylinder 1. 1, an annular rod guide 10 through which the rod 3 passes, a bottom cap 11 which closes the lower opening in FIG. 1 of the cylinder 1, a bottomed cylindrical holder portion 4 and a housing provided side by side 1 and a holder housing composite member H to which the upper end in FIG. 1 of the rod 3 projecting out of the cylinder 1 is connected to the bottom 4a of the holder 4 and a bottomed cylindrical shape accommodated in the housing 5 A bladder 50, a cap 51 that closes the opening of the bladder 50 and the housing portion 5, and a base valve assembly 6 that is attached between the holder portion 4 and the housing portion 5 in the holder housing composite member H. 1 is connected to the cylinder part 4b of the holder part 4 and extends downward in FIG. 1 from the cylinder part 4b, and the outer cylinder 7 in which the cylinder 1 enters and exits inside, and the outer cylinder 7 connected to the outer cylinder 7 and downward in FIG. And an annular extending member 8 extending.

  A telescopic damper main body D is configured by including the cylinder 1, the piston 2, and the rod 3. The reservoir R is configured to include the housing portion 5 of the holder housing composite member H, the bladder 50, and the cap 51, and the reservoir R communicates with the damper main body D. A damper is configured by including a damper body D, a base valve assembly 6, and a reservoir R. In addition, the air cylinder C is configured to include the holder portion 4 of the holder housing composite member H, the outer cylinder 7, and the extension member 8, and the gas is sealed between the air cylinder C and the damper main body D, and the gas A spring is configured.

  Further, brackets 4c and 11a are provided at the upper part in FIG. 1 of the holder part 4 which is both ends of the shock absorber A in the axial direction and at the lower part in FIG. The bracket 4c is connected to the vehicle body, and the bracket 11a is connected to the swing arm via a link or the like. For this reason, when an impact due to road surface unevenness is input to the wheel, the rod 3 enters and exits the cylinder 1 and the damper body D expands and contracts, and the cylinder 1 enters and exits the air cylinder C and the gas spring expands and contracts. The shock absorber A expands and contracts. The application of the shock absorber according to the present invention is not limited to the rear cushion unit, and can be changed as appropriate.

  Hereinafter, each member constituting the shock absorber A will be described.

  The cylinder 1 has a cylindrical shape, extends vertically in FIG. 1, and has screw grooves formed on the inner periphery of both ends. Then, the rod guide 10 is screwed to the upper end portion of the cylinder 1 in FIG. 1, and the bottom cap 11 is screwed to the lower end portion. A space surrounded by the cylinder 1, the rod guide 10, and the bottom cap 11 is a working chamber L, and the working chamber L is divided into two chambers by the piston 2. Of these two chambers, a chamber on the rod 3 side that is compressed when the shock absorber A is expanded is referred to as an expansion side chamber L1, and a chamber on the piston 2 side that is compressed when it is contracted is referred to as a compression side chamber L2. The extension side chamber L1 and the compression side chamber L2 are each filled with a liquid such as hydraulic oil.

  As shown in FIG. 2, the rod guide 10 is connected to a small diameter portion 10a inserted into the cylinder 1 and an upper portion of the small diameter portion 10a in FIG. 2, and the piston portion 10b has an outer diameter larger than the outer diameter of the small diameter portion 10a. The piston portion 10b protrudes from the cylinder 1 outward in the radial direction. The piston portion 10b is in sliding contact with the inner periphery of the outer cylinder 7, and divides the inside of the air cylinder C into a first air chamber G1 on the rod 3 side and a second air chamber G2 on the cylinder 1 side. These will be described in detail later.

  An annular bush 12 is provided on the inner periphery of the rod guide 10, and the rod guide 10 is in sliding contact with the outer periphery of the rod 3 via the bush 12 to support the rod 3 so as to be movable in the axial direction. An annular gas seal 13 that slides on the outer periphery of the rod 3 and prevents the gas in the first air chamber G1 from entering the cylinder 1 is provided on the inner periphery of the rod guide 10 and above the bush 12. An annular liquid seal 14 that slides on the outer periphery of the rod 3 and prevents the liquid in the cylinder 1 from flowing out of the cylinder 1 is provided below the bush 12. Further, the small-diameter portion 10a of the rod guide 10 and the cylinder 1 and the bottom cap 11 (FIG. 1) and the cylinder 1 are respectively sealed with seals not shown. Therefore, the working chamber L is maintained liquid-tight.

  Further, the rod guide 10 is formed with a depressurizing passage 10c that communicates with the second air chamber G2 a space K that is the outer periphery of the rod 3 and is surrounded by the rod guide 10, the gas seal 13, and the liquid seal 14. In addition, a check valve 19 is provided that allows only the flow of liquid from the space K toward the second air chamber G2 through the decompression passage 10c. The check valve 19 blocks the pressure release passage 10c by seating the valve body on the valve seat, but the valve body and the valve seat are sealed with the valve body seated on the valve seat. This prevents the gas in the second air chamber G2 from moving to the space K.

  Further, an annular closing member 15 and an annular rebound cushion 16 are provided on the inner periphery of the lower end of the rod guide 10 in FIG. The closing member 15 is formed in an inverted L-shaped cross section and is in sliding contact with the outer periphery of the rod 3. The rebound cushion 16 is formed of an elastomer such as rubber and has elasticity. The rebound cushion 16 is provided on the outer periphery of the portion of the closing member 15 that is in sliding contact with the outer periphery of the rod 3, and the back surface is supported by the rod guide 10 and the closing member 15. When the rod 3 is withdrawn from the cylinder 1 by a predetermined amount, the valve stopper 23 fixed to the outer periphery of the rod 3 comes into contact with the rebound cushion 16 and the rebound cushion 16 is elastically deformed, and the shock at the time of the maximum extension of the shock absorber A is applied. ease.

  As shown in FIG. 1, the rod 3 is arranged in the cylinder 1 connected to the main body 3 a supported by the rod guide 10 and the lower side of the main body 3 a in FIG. 1, and has an outer diameter outside the main body 3 a. An attachment portion 3b having a diameter smaller than that of the main body portion 3a is connected to the upper side of the main body portion 3a in FIG. And while the connection part 3c is connected with the holder part 4, the main-body part 3a passes the inner side of the outer cylinder 7 and the rod guide 10, and the cyclic | annular piston 2 is mounted to the outer periphery of the attachment part 3b. More specifically, a screw groove is formed on the outer periphery of the tip portion of the mounting portion 3b, and the piston 2 is interposed between a nut 30 that is screwed onto the outer periphery of the tip portion and a step formed at the end of the mounting portion 3b. It is pinched and fixed.

  Further, the rod 3 is formed with a vertical hole 3d passing through the central portion in the axial direction, and a horizontal hole 3e that opens to the side near the attachment portion 3b in the main body 3a and communicates with the vertical hole 3d. The horizontal hole 3e is closed by the closing member 15 when the shock absorber A is fully extended, and communicates with the extension side chamber L1 in the normal stroke range. Further, since the vertical hole 3d always communicates with the compression side chamber L2, in the normal stroke range where the horizontal hole 3e is not closed, the liquid moves between the extension side chamber L1 and the compression side chamber L2 through the rod 3. it can. That is, the vertical hole 3d and the horizontal hole 3e constitute a bypass path that bypasses an expansion side valve 20 and a pressure side valve 21, which will be described later, stacked on the piston 2, and this bypass path is a blocking member when the shock absorber A is fully extended. Blocked at 15. Further, the lateral hole 3e functions as a throttle and provides resistance to the flow of liquid moving between the expansion side chamber L1 and the compression side chamber L2.

  The piston 2 is formed with an extension side passage 2a and a pressure side passage 2b communicating the extension side chamber L1 and the pressure side chamber L2. Further, the expansion side valve 20 for opening and closing the outlet of the expansion side passage 2a is stacked on the lower side of the piston 2 in FIG. 1, and the pressure side valve for opening and closing the outlet of the compression side passage 2b on the upper side of the piston 2 in FIG. 21 are laminated. The expansion side valve 20 and the pressure side valve 21 are both leaf valves, and the inner peripheral portion thereof is fixed to the outer periphery of the rod 3 together with the piston 2 by a nut 30 in a state in which the deflection on the outer peripheral side is allowed. Therefore, the expansion side valve 20 can open the expansion side passage 2a when bent by receiving the pressure of the expansion side chamber L1, and the pressure side valve 21 can open the pressure side passage 2b when bent by receiving the pressure of the compression side chamber L2. The expansion side valve 20 and the pressure side valve 21 are not limited to leaf valves, and can be changed as appropriate, such as poppet valves or orifices.

  Further, valve stoppers 22 and 23 are laminated on the lower side of the expansion side valve 20 in FIG. 1 and the upper side of the compression side valve 21, respectively. The valve stoppers 22 and 23 contact the back surface of the valve when the corresponding expansion side valve 20 or compression side valve 21 is bent by a predetermined amount, and prevent the valve from further bending to limit the opening amount of the valve. Further, the valve stopper 23 also serves as a rebound stopper and, as described above, abuts against the rebound cushion 16 when the shock absorber A is fully extended.

  Subsequently, the holder housing composite member H connected to the upper end of the rod 3 in FIG. 1 is a bottomed cylindrical shape, and the holder portion 4 is arranged with the opening facing downward in FIG. 1 and includes a housing part 5 which is a bottomed cylinder and is arranged with the opening facing downward in FIG. 1, and a connection part 9 connecting the holder part 4 and the housing part 5. As described above, the holder part 4 is a part of the air cylinder C, and the housing part 5 is a part of the reservoir R. The holder housing composite member H is also formed with a liquid passage 90 that communicates between the working chamber L and the reservoir R through the vertical hole 3d, and a gas passage 91 that communicates between the air cylinder C and the reservoir R. . Further, the base valve assembly 6 is attached to the connecting portion 9, and the liquid flowing through the liquid passage 90 moves between the working chamber L and the reservoir R via the base valve assembly 6.

  Further, a bladder 50 having a bottomed cylindrical shape that can be expanded and contracted is inserted into the housing portion 5 with the bottom portion facing the bottom portion of the housing portion 5. A cap 51 is attached to the opening end of the cylindrical portion of the housing portion 5. The cap 51 fixes the opening end of the bladder 50 to the housing portion 5 and closes the opening of the bladder 50. Inside the housing part 5, a liquid chamber L3 filled with liquid is formed between the bladder 50 and the housing part 5, and an air chamber G3 in which gas is sealed is formed inside the bladder 50. . As described above, the reservoir R is a separate tank provided outside the damper main body D, and includes the liquid chamber L3 and the air chamber G3 partitioned by the bladder 50. In the reservoir R, the member that partitions the liquid chamber L3 and the air chamber G3 is not limited to the bladder 50, and may be a free piston or a bellows.

  The liquid chamber L3 of the reservoir R communicates with the working chamber L through the liquid passage 90 and the vertical hole 3d of the rod 3, and the air chamber G3 communicates with the first air chamber G1 through the gas passage 91. More specifically, the cap 51 is formed in a bottomed cylindrical shape, with the bottom portion 51a facing the opening side of the housing portion 5, and the tubular portion 51b facing the inside of the housing portion 5 and being inserted into the housing portion 5. Has been. And the bladder 50 is connected with the outer periphery of the front-end | tip part of the cylinder part 51b. In addition, a plurality of through holes 51c penetrating through the thickness of the cylinder portion 51b are formed in the cylinder portion 51b of the cap 51 side by side in the circumferential direction. An annular groove 5a along the circumferential direction is formed in a portion of the inner periphery of the housing portion 5 facing the opening of the through hole 51c, and a gas passage 91 opens inside the annular groove 5a. In addition, the outer periphery of the housing part 5 on the outside air side with respect to the annular groove 5 a is closed with a seal 52. Therefore, the gas in the first air chamber G1 moves into the air chamber G3 through the gas passage 91, the gap formed between the housing portion 5 and the cap 51 by the annular groove 5a, and the through hole 51c in this order. The gas in the air chamber G3 can also move in the reverse direction through the passage to the first air chamber G1.

  In addition, the base valve assembly 6 provided in the connecting portion 9 is provided in the middle of the liquid passage 90, and is formed with a partition wall (not shown) that partitions the working chamber L and the liquid chamber L3, and is formed in the partition wall so as to form the working chamber L and the liquid. A suction passage 6a and a discharge passage 6b communicating with the chamber L3, a check valve 60 that allows only a flow of liquid from the liquid chamber L3 to the working chamber L through the suction passage 6a, and a discharge passage 6b from the working chamber L to the liquid chamber A damping valve 61 is provided that provides resistance to the flow of liquid toward L3 and blocks the flow in the opposite direction.

  Further, as shown in FIG. 1, the holder part 4 has a bottom part 4a and a cylindrical part 4b extending from the outer peripheral part of the bottom part 4a to one side, and the outer cylinder 7 is screwed to the inner periphery of the tip part of the cylindrical part 4b. Is done. The cylindrical part 4 b has an outer diameter on the bottom part 4 a side that is smaller than the outer diameter of the outer cylinder 7. A bracket 4c is provided above the bottom 4a in FIG. 1, and the bracket 4c is connected to the vehicle body. The small diameter portion of the cylindrical portion 4b is a portion where the rod guide 10 does not slide and the inner diameter can be made smaller than the inner diameter of the outer cylinder 7 with which the rod guide 10 is slidably contacted. Can also be reduced. Thus, in the air cylinder C, if the outer diameter of the portion where the rod guide 10 is not in sliding contact is smaller than the outer diameter of the sliding contact portion, even if the outer diameter of the sliding portion, that is, the outer cylinder 7 is increased, When the shock absorber A is attached to the vehicle body, interference between the shock absorber A and the vehicle body can be avoided and the attachment can be facilitated.

  Further, an annular nut portion 4d that protrudes inward of the cylindrical portion 4b is provided below the bottom portion 4a in FIG. A rod 3 is screwed onto the inner periphery of the nut portion 4 d, and the rod 3 is prevented from loosening by using a lock nut 31. Further, a bump cushion 32 is attached to the outer periphery of the rod 3 below the lock nut 31. The bump cushion 32 is formed of an elastomer such as rubber and has elasticity. When the rod 3 enters the cylinder 1 by a predetermined amount, the bump cushion 32 comes into contact with the rod guide 10 and is elastically deformed so that the shock at the time of the most contraction of the shock absorber A is applied. ease.

  Subsequently, the outer cylinder 7 extends vertically in FIG. 1, and screw grooves are formed on the outer periphery of the upper end and the outer periphery of the lower end. The upper end of the outer cylinder 7 in FIG. 1 is screwed to the inner periphery of the holder portion 4, and the lower end of FIG. 1 is screwed to the inner periphery of the extension member 8. The piston portion 10b of the rod guide 10 is in sliding contact. As shown in FIG. 2, an annular bush 17 is provided on the outer periphery of the piston portion 10 b, and the rod guide 10 is in sliding contact with the inner periphery of the outer cylinder 7 via the bush 17. In addition, an annular seal 18 is provided on the outer periphery of the piston portion 10b so as to be in sliding contact with the bush 17 and the inner periphery of the outer cylinder 7, and the gap between the rod guide 10 and the outer cylinder 7 is closed with the seal 18. A seal 70 (FIG. 1) closes the space between the outer cylinder 7 and the holder portion 4. And gas, such as air, is enclosed in the space surrounded by the holder portion 4, the outer cylinder 7, and the rod guide 10 on the outer periphery of the rod 3, and this portion is the first air chamber G1, It is kept airtight.

  When the shock absorber A contracts, the cylinder 1 enters the air cylinder C, and the air cylinder C descends with respect to the rod guide 10, so that the gas in the first air chamber G1 is compressed by the rod guide 10, The pressure in the first air chamber G1 increases. On the other hand, when the shock absorber A is extended, the cylinder 1 is retracted from the air cylinder C and the air cylinder C is lifted with respect to the rod guide 10, so that the volume of the first air chamber G1 is increased and the first air chamber is increased. The pressure in G1 becomes low. Thus, the rod guide 10 functions as an air piston that compresses the gas in the first air chamber G1, and the main spring S1 that has the air cylinder C, the rod guide 10, and the first air chamber G1 is a gas spring. Composed. The elastic force of the main spring S1 increases as the shock absorber A contracts and the pressure in the first air chamber G1 increases, and the main spring S1 urges the damper body D in the extending direction to elasticize the vehicle body. Functions as a supporting suspension spring.

  As described above, the first air chamber G1 communicates with the air chamber G3 through the gas passage 91. For this reason, the pressure in the 1st air chamber G1 and the pressure in the air chamber G3 are equal, and the said air chamber G3 comprises the main spring S1 with the 1st air chamber G1. Although not shown, the gas passage 91 is connected to a gas supply / exhaust passage that opens to the outside of the connecting portion 9, and an air valve is attached to the open end of the gas supply / exhaust passage. Therefore, gas can be supplied to and discharged from the first air chamber G1 and the air chamber G3 via the air valve, and these pressures can be changed simultaneously, and the elastic force of the main spring S1 can be adjusted.

  Subsequently, as shown in FIG. 2, the extending member 8 has an annular bottom portion 8 a that allows the cylinder 1 to be inserted, and a cylindrical portion 8 b that extends upward from the outer peripheral portion of the bottom portion 8 a in FIG. 2. The tip end of 8b is screwed to the outer periphery of the outer cylinder 7. An annular bush 80 is provided on the inner periphery of the bottom 8 a, and the extension member 8 is in sliding contact with the outer periphery of the cylinder 1 via the bush 80. Further, annular seals 81 and 82 that are in sliding contact with the outer periphery of the cylinder 1 are provided on the inner periphery of the bottom 8a and below the bush 80 in FIG. 2, and the seals 81 and 82 are provided between the extension member 8 and the cylinder 1. While being closed, the space between the outer cylinder 7 and the extension member 8 is closed with a seal 83. A gas such as air is sealed in the outer periphery of the cylinder 1 and surrounded by the outer cylinder 7, the extension member 8, and the piston portion 10 b of the rod guide 10. It is kept airtight.

  When the shock absorber A contracts, the cylinder 1 enters the air cylinder C and the air cylinder C descends with respect to the rod guide 10, so that the volume of the second air chamber G2 is increased and the second air chamber G2 is expanded. The pressure of becomes low. On the contrary, when the shock absorber A is extended, the cylinder 1 is withdrawn from the air cylinder C and the air cylinder C is raised with respect to the rod guide 10, so that the gas in the second air chamber G2 is compressed by the piston portion 10b. Thus, the pressure in the second air chamber G2 increases. Thus, the piston portion 10b of the rod guide 10 functions as an air piston that compresses the gas in the second air chamber G2, and includes the air cylinder C, the rod guide 10, and the second air chamber G2, and is a gas spring. A balance spring S2 is configured. The elastic force of the balance spring S2 increases as the shock absorber A expands and the pressure in the second air chamber G2 increases, and the balance spring S2 opposes the damper main body D in the contracting direction, opposite to the main spring S1. To power.

  The extension member 8 is formed with a gas supply / discharge passage 8c (FIG. 2) that obliquely penetrates the bottom portion 8a, and an air valve 84 is attached to the gas supply / discharge passage 8c. Therefore, gas can be supplied to and discharged from the second air chamber G2 via the air valve 84, the pressure in the second air chamber G2 can be changed, and the elastic force of the balance spring S2 can be adjusted. Further, the air valve 84 is disposed such that its tip protrudes upward in FIG. 2 from the bottom 8a of the extension member 8 and protrudes into the second air chamber G2.

  As described above, the shock absorber A includes the main spring S1 and the balance S2 spring in which the direction in which the damper main body D is biased is reversed. Therefore, when the shock absorber A is mounted on the vehicle, the ride comfort of the vehicle is improved. Can be good. More specifically, although the vehicle body can be elastically supported only by the main spring S1, the spring characteristic of the entire shock absorber becomes the characteristic of only the main spring S1. Since the main spring S1 is a gas spring, the spring characteristic is a non-linear characteristic. And if the spring characteristic of the shock absorber is set in accordance with the desired characteristic of the second half of the stroke on the most contracted side, the elastic force in the first half of the stroke, particularly in the vicinity of the maximum extension, becomes excessive, thereby deteriorating riding comfort. There is a fear. Therefore, if the balance spring S2 is added to assist the contraction of the shock absorber A in the vicinity of the maximum extension, the riding comfort of the vehicle can be improved. In particular, in order to improve the ride comfort of the vehicle, the elastic force acting in the extension direction of the main spring S1 when the shock absorber A is at its maximum extension is offset by the balance spring S2, and the balance with the spring characteristics of the main spring S1. It is preferable to approximate the combined characteristic of the spring characteristic of the spring S2 to the characteristic of the coil spring by making it close to a proportional characteristic proportional to the stroke amount.

  Hereinafter, the operation of the shock absorber A according to the present embodiment will be described.

  When the rod 3 is withdrawn from the cylinder 1 and the cylinder 1 is withdrawn from the air cylinder C and the shock absorber A is extended, the piston 2 moves upward in FIG. 1 to compress the extension side chamber L1. The compression side chamber L2 expands. Then, the pressure in the expansion side chamber L1 to be compressed rises, and the liquid in the expansion side chamber L1 pushes open the expansion side valve 20, passes through the expansion side passage 2a, and moves to the compression side chamber L2. In the cylinder 1, the liquid corresponding to the retracted rod volume is insufficient, but the check valve 60 is opened and the liquid corresponding to the shortage is supplied from the liquid chamber L3 to the pressure side chamber L2 through the suction passage 6a. Since resistance is given by the expansion side valve 20 to the flow of liquid from the expansion side chamber L1 to the compression side chamber L2, the pressure in the expansion side chamber L1 rises. On the other hand, since the pressure side chamber L2 receives the supply of the liquid from the liquid chamber L3, the pressure in the pressure side chamber L2 becomes substantially equal to the pressure in the reservoir R. Therefore, a difference occurs between the pressures in the extension side chamber L1 and the pressure side chamber L2, and this differential pressure acts on the piston 2 so that the damper exhibits a damping force that prevents the buffer A from extending.

  Further, when the shock absorber A is extended, the air cylinder C rises with respect to the cylinder 1, so that the volume of the first air chamber G1 is increased and the volume of the second air chamber G2 is reduced. Furthermore, when the shock absorber A is extended, the liquid corresponding to the volume of the rod that retreats from the cylinder 1 flows out of the liquid chamber L3, and accordingly, the bladder 50 is expanded and the volume of the air chamber G3 is expanded. Therefore, when the shock absorber A is extended, the elastic force of the main spring S1 configured with the first air chamber G1 and the air chamber G3 decreases, and the balance spring configured with the second air chamber G2. The elastic force of S2 increases and the force pushing up the vehicle body as the entire shock absorber A decreases.

  On the other hand, when the rod 3 enters the cylinder 1 and the cylinder 1 enters the air cylinder C and the shock absorber A contracts, the piston 2 moves downward in FIG. The extension side chamber L1 is expanded by being compressed. Then, the pressure in the pressure side chamber L2 to be compressed rises, and the liquid in the pressure side chamber L2 pushes open the pressure side valve 21, passes through the pressure side passage 2b, and moves to the extension side chamber L1. In the cylinder 1, the liquid for the volume of the rod that has entered becomes surplus, but this surplus liquid pushes the damping valve 61 open, passes through the discharge passage 6b, and moves to the liquid chamber L3. Since resistance is given by the pressure side valve 21 and the damping valve 61 to the flow of liquid from the pressure side chamber L2 toward the extension side chamber L1 and the liquid chamber L3, the pressure in the pressure side chamber L2 rises. On the other hand, the pressure in the expansion side chamber L1 which expands falls. Therefore, a difference occurs in the pressure between the compression side chamber L2 and the extension side chamber L1, and this differential pressure acts on the piston 2 so that the damper exhibits a damping force that prevents the shock absorber A from contracting.

  Further, when the shock absorber A contracts, the air cylinder C descends with respect to the cylinder 1, so that the volume of the first air chamber G1 is reduced and the volume of the second air chamber G2 is increased. Further, when the shock absorber A is contracted, the liquid corresponding to the volume of the rod entering the cylinder 1 flows into the liquid chamber L3, and accordingly, the bladder 50 is reduced and the volume of the air chamber G3 is reduced accordingly. Therefore, when the shock absorber A contracts, the elastic force of the main spring S1 configured with the first air chamber G1 and the air chamber G3 increases, and the balance spring configured with the second air chamber G2. The elastic force of S2 decreases, and the force that pushes up the vehicle body as the entire shock absorber A increases.

  Further, when the shock absorber A expands and contracts within a normal stroke range, the lateral hole 3e provided in the rod 3 communicates with the extension side chamber L1. For this reason, at the time of expansion / contraction of the shock absorber A, a part of the liquid moving between the expansion side chamber L1 and the compression side chamber L2 bypasses the expansion side passage 2a and the compression side passage 2b, and the horizontal hole 3e and the vertical hole 3d Pass through the configured bypass. However, when the shock absorber A extends beyond the normal stroke range, the horizontal hole 3e provided in the rod 3 is closed by the closing member 15, so that the bypass path is blocked. Then, since the flow rate of the liquid passing through the expansion side valve 20 increases, the damping force increases, and the extension operation of the shock absorber A can be suppressed with the large damping force.

  Further, when the shock absorber A extends beyond the normal stroke range, the rebound cushion 16 is compressed by the valve stopper 23 and exerts an elastic force, and the expansion operation of the shock absorber A is suppressed. As described above, in the shock absorber A, the shock absorber A can be prevented from extending beyond the normal stroke range by both the blocking of the bypass path by the closing member 15 and the rebound cushion 16. The effect of mitigating the impact is high. However, one of the lateral hole 3e or the rebound cushion 16 may be discarded.

  On the other hand, when the shock absorber A contracts beyond the normal stroke range, the bump cushion 32 is compressed by the rod guide 10 to exert an elastic force, and the contraction operation of the shock absorber A is suppressed.

  Further, when the shock absorber A is contracted most, the rod guide 10 approaches the bottom 4a of the holder portion 4 and the volume of the first air chamber G1 becomes very small. However, the first air chamber G1 passes through the gas passage 91. It is connected to the air chamber G3 of the reservoir R. And since it has the 1st air chamber G1 and the air chamber G3 and the main spring S1 is comprised, the volume of the air chamber which comprises the main spring S1 is ensured, and it can prevent that a compression ratio becomes excessive. . Therefore, even if the shock absorber A contracts most, the volume of the air chamber constituting the main spring S1 does not become too small, the pressure in the first air chamber G1 becomes excessive, and the seals 13, 18, 70, etc. are large. The load can be prevented.

  Furthermore, even if the shock absorber A repeatedly expands and contracts and liquid is accumulated in the space K and the pressure in the space K rises, the check valve 19 is activated when the pressure in the space K exceeds the pressure in the second air chamber G2. The liquid in the space K moves to the second air chamber G2 through the depressurization passage 10c. Specifically, the pressure in the second air chamber G2 decreases as the shock absorber A contracts, and decreases to near atmospheric pressure at the time of the maximum contraction. For this reason, when the pressure in the space K becomes equal to or higher than the atmospheric pressure, and the shock absorber A contracts to near the maximum contraction and exceeds the pressure in the second air chamber G2, the check valve 19 opens, and the liquid in the space K It moves to the 2nd air chamber G2, and the pressure in the space K falls to the pressure in the 2nd air chamber G2. Furthermore, if the shock absorber A contracts most, the pressure in the space K becomes equal to or lower than the lowest pressure in the second air chamber G2.

  Hereinafter, the function and effect of the shock absorber A according to the present embodiment will be described.

  In the present embodiment, the outer diameter of the upper end portion (on the opposite side of the cylinder) in FIG. 1 of the air cylinder C is formed smaller than the outer diameter of the lower side (cylinder 1 side). For this reason, in the air cylinder C, even when the outer diameter of the portion (the outer cylinder 7) with which the rod guide 10 is slidably contacted is increased, when the shock absorber A is attached to the vehicle body, the air cylinder C interferes with peripheral components of the shock absorber A. Can be prevented and can be easily mounted. Further, in the air cylinder C, when the outer diameter of the portion where the rod guide 10 is slidably contacted is increased, the inner diameter is increased accordingly, and the outer diameter of the rod guide 10 that is an air piston can be increased. Thus, when the outer diameter of the rod guide 10 is increased, the area of the pressure receiving surface (pressure receiving area) that receives the pressure of the first air chamber G1 in the rod guide 10 and the area of the pressure receiving surface that receives the pressure of the second air chamber G2. Since the (pressure receiving area) can be increased, the pressure in the first air chamber G1 and the pressure in the second air chamber G2 can be reduced. Therefore, it is possible to reduce the load applied to the seals (seal 13, 18, 70, 82, 81, etc.) that prevent the gas enclosed in the air chamber from flowing out.

  The shape of the air cylinder C is not limited to the above and can be changed as appropriate. For example, the outer diameter of the air cylinder C may be constant in the axial direction. Further, in the shock absorber A, the air cylinder C is configured by assembling the holder part 4 of the holder housing composite member H formed separately, the outer cylinder 7 and the extension member 8. Either or all of the cylinder 7 and the extension member 8 may be integrally formed as one part.

  Further, in the present embodiment, the shock absorber A is a reservoir provided outside the first air chamber G1 and having a liquid chamber L3 communicating with the working chamber L and an air chamber G3 communicating with the first air chamber G1. R is provided. According to the said structure, the air chamber G3 of the reservoir | reserver R provided outside the 1st air chamber G1 also comprises the main spring S1 with the 1st air chamber G1. The reservoir R is a member necessary to compensate for a change in volume in the cylinder corresponding to the volume of the rod entering and leaving the cylinder 1 and a change in volume due to a change in temperature of the liquid stored in the cylinder 1. That is, in the shock absorber A, the air chamber G3 of the reservoir R is also used as the air chamber constituting the main spring S1, so that even if the air chamber volume constituting the main spring S1 is secured, the buffer A An increase in the weight of the vessel A can be suppressed. Therefore, even if the air chamber volume is secured and the compression ratio of the air chamber constituting the main spring S1 is suppressed from becoming too large, the weight of the shock absorber A is suppressed from increasing, and the main spring S1 is The effect of weight reduction due to the spring can be sufficiently obtained.

  The first air chamber G1 and the air chamber G3 of the reservoir R may be separated, and the air chamber constituting the main spring S1 may be composed only of the first air chamber G1. 1 may be connected to the lower end of the middle. The change is possible regardless of the shape and configuration of the air cylinder C.

  In the present embodiment, the reservoir R is a tank in which a liquid chamber L3 and an air chamber G3 are formed, and is connected to the air cylinder C. According to this configuration, since the air cylinder C and the reservoir R do not move relative to each other, when the first air chamber G1 and the air chamber G3 are communicated with each other through the passage, the passage can be easily handled.

  Here, when the reservoir R is connected to the bottom cap 11 side of the cylinder 1, it is necessary to consider that the reservoir and the air cylinder do not interfere when the shock absorber is extended and contracted, and the outer diameter of the air cylinder is limited by the reservoir. May be. However, according to the above configuration, there is no concern about interference between the reservoir R and the air cylinder C due to expansion and contraction of the shock absorber A, and the outer diameter of the air cylinder C can be increased. Then, since the inner diameter of the air cylinder C can be increased and the pressure receiving area of the rod guide 10 that is an air piston can be increased, the pressure in the first air chamber G1 and the pressure in the second air chamber G2 can be reduced. Therefore, it is possible to reduce the load applied to the seals (seal 13, 18, 70, 82, 81, etc.) that prevent the gas enclosed in the air chamber from flowing out.

  Furthermore, according to the above configuration, the reservoir R is a tank that is externally attached to the damper main body D, and is connected to the air cylinder C. Therefore, even if the reservoir R is provided outside the first air chamber G1. The reservoir R does not increase in size, and the shock absorber A can be reduced in weight. In addition, as shown in FIG. 1, when the reservoir R and the air cylinder C are provided side by side, the shock absorber A is not bulky in the axial direction, and the mountability to the vehicle can be improved. The term “side by side” as used herein refers to a state in which the reservoir R and the air cylinder C are arranged side by side in the front-rear or left-right direction of the vehicle when the shock absorber A is attached. You may lean on.

  The arrangement of the reservoir R is not limited to the above, and can be changed as appropriate. For example, a housing may be provided so as to cover the outer periphery of the outer cylinder 7, and the air chamber G3 and the liquid chamber L3 of the reservoir R may be formed in a cylindrical gap formed between the housing and the outer cylinder 7. Further, as described above, the reservoir R may be connected to the lower portion of the cylinder 1 in FIG. 1 and the air chamber G3 and the first air chamber G1 of the reservoir R may be connected by a hose or the like. The chamber G1 may be separated. These changes are possible regardless of the shape and configuration of the air cylinder C.

  Further, in the present embodiment, the rod 3 is inserted into the first air chamber G1, and a vertical hole (passage) 3d that connects the working chamber L and the liquid chamber L3 is formed in the rod 3. Therefore, when connecting the reservoir R to the air cylinder C, it is not necessary to add a member for forming a passage for communicating the liquid chamber L3 and the working chamber L to the outside of the damper body D. Thus, the configuration of the shock absorber A can be simplified. A passage that communicates between the liquid chamber L3 and the working chamber L may be provided outside the damper body D, and the configuration of the passage that communicates between the liquid chamber L3 and the working chamber L can be changed as appropriate. The change can be made regardless of the shape and configuration of the air cylinder C and the communication / blocking of the first air chamber G1 and the air chamber G3.

  Moreover, in this Embodiment, it arrange | positions so that the front-end | tip of the air valve 84 provided in the gas supply / discharge path 8c for supplying / exhausting gas to the 2nd air chamber G2 may protrude in the 2nd air chamber G2. For this reason, even if the liquid discharged | emitted from the space K has accumulated in the 2nd air chamber G2, the front-end | tip of the air valve 84 protrudes from a liquid level. Therefore, when the gas in the second air chamber G2 is extracted from the gas supply / discharge path 8c, the liquid does not leak from the air valve 84. Moreover, when supplying gas into the 2nd air chamber G2 from the gas supply / discharge path 8c, the liquid in the 2nd air chamber G2 does not foam. Note that the arrangement of the air valves 84 is not limited to the illustration, and can be changed as appropriate. The change is possible regardless of the shape and configuration of the air cylinder C, the communication / blocking of the first air chamber G1 and the air chamber G3, and the configuration of the passage for connecting the liquid chamber L3 and the working chamber L. It is.

  Further, in the present embodiment, the shock absorber A includes a cylinder 1 in which a working chamber L in which a liquid is accommodated is formed, and the shock absorber A is movably inserted into the cylinder 1 so that the working chamber L is extended to the extension chamber (room ) Piston 2 partitioned into L1 and pressure side chamber (room) L2, a rod 3 connected to the piston 2 and extending outward from the cylinder 1, and connected to the rod 3 so that the cylinder 1 is movably inserted inside. The air cylinder C is connected to the cylinder 1 to support the rod 3 movably, and the first air chamber G1 on the rod 3 side in which gas is sealed in the air cylinder C and the second air chamber G2 on the cylinder 1 side An annular rod guide 10 that is divided into two, a liquid seal 14 that is provided on the inner periphery of the rod guide 10 and that is in sliding contact with the outer periphery of the rod 3 and maintains the working chamber L in a liquid-tight state, and an inner periphery of the rod guide 10 There is a liquid seal 1 1 is a gas seal 13 provided on the upper side in FIG. 1 (on the first air chamber G1 side) and in sliding contact with the outer periphery of the rod 3 to keep the first air chamber G1 airtight, and the inner periphery of the rod guide 10. And a pressure relief passage 10c that communicates a space K formed between the liquid seal 14 and the gas seal 13 to the second air chamber G2, and a pressure relief passage 10c, and travels from the space K to the second air chamber G2. And a check valve 19 that allows only a liquid flow.

  According to the above configuration, the main spring S1 that is a gas spring is provided with the first air chamber G1, and the vehicle body can be elastically supported by the main spring S1. Even if the main spring S1 which is a gas spring is provided in this way, when the pressure in the space K becomes higher than the pressure in the second air chamber G2, the check valve 19 opens, and the pressure in the space K is increased to the second pressure. It is possible to escape to the air chamber G2. Therefore, since the inside of the space K can be prevented from becoming a high pressure, the back surface (the space K side) of the gas seal 13 is pushed by the pressure in the space K, and the sealing performance of the gas seal 13 is reduced. The gas in the air chamber G1 can be prevented from entering the cylinder 1. And since the penetration | invasion of the gas in the cylinder 1 can be prevented, the responsiveness of damping force generation | occurrence | production of the buffer A can be maintained favorable.

  The type of valve provided in the pressure relief passage 10c is not limited to the check valve, and may be changed as appropriate as long as the pressure relief passage 10c is one-way and allows only the fluid flow from the space K to the second air chamber G2. it can. For example, the valve provided in the pressure relief passage 10c may be a relief valve. 1 and 2 show the check valve 19 without a spring, the configuration of the check valve can be changed as appropriate, and the check valve may have a spring. Such changes include the shape and configuration of the air cylinder C, the communication between the first air chamber G1 and the air chamber G3, the configuration of the passage for connecting the liquid chamber L3 and the working chamber L, and the air valve. This is possible regardless of the 84 arrangement.

  Moreover, according to the said structure, the balance spring S2 is comprised including the 2nd air chamber G2, and the shrinkage | contraction near the time of the maximum expansion of the buffer A is assisted by this balance spring S2. For this reason, when the shock absorber A is mounted on the vehicle, the riding comfort of the vehicle can be improved. Furthermore, since both the main spring S1 and the balance spring S2 are gas springs, the weight of the shock absorber A as a whole is less affected by temperature changes as well as being lightened.

  For example, when the shock absorber A is heated, the temperature in the first air chamber G1 and the second air chamber G2 increases, and the pressure in the first air chamber G1 and the second air chamber G2 increases, and the main spring Although the elastic force of S1 and balance spring S2 increases, as described above, the elastic force of main spring S1 acts in the direction of extending damper body D, whereas the elastic force of balance spring S2 causes damper body D to move. This is because the amount of elastic force of the main spring S1 and the amount of elastic force of the balance spring S2 cancel each other because they act in the contracting direction. In particular, when the shock absorber A is a rear cushion unit as in the present embodiment, the shock absorber A is disposed near the engine and is warmed by the heat of the engine, so that both the main spring S1 and the balance spring S2 are gas springs. Is particularly effective.

  Note that a metal spring such as a coil spring may be housed in the second air chamber G2, and a balance spring may be configured by the spring and the gas spring. Such changes include the shape and configuration of the air cylinder C, the communication between the first air chamber G1 and the air chamber G3, the configuration of the passage for connecting the liquid chamber L3 and the working chamber L, the air valve 84 This is possible regardless of the arrangement and the type and configuration of the valves provided in the pressure relief passage 10c.

  The preferred embodiments of the present invention have been described above in detail, but modifications, changes and modifications can be made without departing from the scope of the claims.

A ... shock absorber, C ... air cylinder, G1 ... first air chamber, G2 ... second air chamber, K ... space, L ... working chamber, L1 ... extension Side chamber (room), L2 ... Pressure side chamber (room), 1 ... Cylinder, 2 ... Piston, 3 ... Rod, 10 ... Rod guide, 10c ... Pressure relief passage, 13. ..Gas seal, 14 ... liquid seal, 19 ... check valve (valve)

Claims (1)

A cylinder in which a working chamber in which liquid is stored is formed;
A piston that is movably inserted into the cylinder and divides the working chamber into two chambers;
A rod connected to the piston and extending outward of the cylinder;
An air cylinder coupled to the rod and into which the cylinder is movably inserted;
An annular rod guide that is connected to the cylinder and supports the rod in a movable manner, and divides the air cylinder into a first air chamber on the rod side and a second air chamber on the cylinder side in which gas is sealed. When,
A liquid seal provided on the inner periphery of the rod guide and in sliding contact with the outer periphery of the rod to maintain the working chamber liquid-tight;
A gas seal which is provided on the inner side of the rod guide and is closer to the first air chamber than the liquid seal and is in sliding contact with the outer periphery of the rod, and maintains the first air chamber airtight;
A depressurization passage communicating with the second air chamber in a space formed between the liquid seal and the gas seal on the inner periphery of the rod guide;
A shock absorber provided with a valve provided in the decompression passage and allowing only a liquid flow from the space toward the second air chamber.

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