JP6630201B2 - Shock absorber - Google Patents

Description

  The present invention relates to a shock absorber.

  2. Description of the Related Art Conventionally, among shock absorbers used for straddle-type vehicles such as two-wheeled vehicles or three-wheeled vehicles, there is a type in which a suspension spring is replaced by a gas spring instead of a metal coil spring for the purpose of weight reduction.

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

  Further, the shock absorber is provided with an annular rod guide which is connected to a cylinder and slidably supports the rod, and an oil seal which is in sliding contact with the outer periphery of the rod is provided on the inner periphery of the rod guide. An air seal is provided on the inner circumference of the guide and closer to the air chamber than the oil seal, in sliding contact with the outer circumference of the rod. According to this configuration, the air seal can prevent the pressure in the air chamber from acting on the oil seal even if the pressure in the air chamber increases due to the contraction of the shock absorber. 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-T-2001-501155, FIGS. 9 and 10

  Here, when the shock absorber provided with the gas spring extends, most of the hydraulic oil attached to the outer periphery of the rod is scraped off by the oil seal when the rod withdraws from the cylinder. An oil film is formed thinly on the outer periphery of. When the rod passes through the air seal, a very small portion of the oil film adhered to the outer periphery of the rod may be scraped off by the air seal and accumulated in the space between the air seal and the oil seal. Furthermore, if the hydraulic oil in the space is scraped off by the oil seal and left in the space at the time of contraction of the shock absorber when the rod enters the cylinder, if the shock absorber repeatedly expands and contracts over a long period of time, There is a case where hydraulic oil is accumulated in the inside and the pressure in the space becomes high.

  As described above, when the space becomes high pressure due to the accumulation of the hydraulic oil, the high pressure acts on the air seal receiving the pressure from the air chamber side from the space side which is the back surface of the air seal, thereby deteriorating the sealing performance of the air seal, The gas in the air chamber may enter the interior. When gas enters the cylinder, the response of the damper to generate damping force decreases, which is not preferable.

  Then, an object of the present invention is to provide a shock absorber which can prevent gas from entering into a cylinder even if it has a gas spring.

  The invention according to claim 1, which solves the above-mentioned problem, has a rod movably inserted into a cylinder in which a working chamber in which a liquid is stored is formed, and the cylinder connected to the rod and having the cylinder inside. An air cylinder movably inserted, a first air chamber on the rod side, and a second air chamber on the cylinder side, which are connected to the cylinder and movably support the rod, and in which gas is sealed in the air cylinder. An annular rod guide partitioned into an air chamber, a liquid seal and a gas seal provided on the inner circumference of the rod guide, and an inner circumference of the rod guide and the liquid seal and the gas seal. A pressure release passage communicating the space formed therebetween to the second air chamber, and a valve provided in the pressure release passage and allowing only a flow of liquid from the space to the second air chamber are provided. As a result, the pressure can be released from the space to the second air chamber, so that the inside of the space is prevented from becoming high pressure, and the high pressure acts on the back surface of the gas seal, thereby deteriorating the sealing performance of the gas seal. Can be prevented.

  ADVANTAGE OF THE INVENTION According to the shock absorber of this invention, even if it has a gas spring, invasion of gas into a cylinder can be prevented.

It is a longitudinal section showing the shock absorber concerning one embodiment of the present invention. It is the figure which expanded a part of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Like reference numerals throughout the several figures refer to like 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 frame of the vehicle body and a rear portion of the frame. This is a rear cushion unit unit that is interposed between a swing arm that supports a rear wheel.

  The shock absorber A includes a cylinder 1, a piston 2 slidably inserted into the cylinder 1, a rod 3 having a lower end connected to the piston 2 in FIG. 1, an annular rod guide 10 that closes the upper opening in the middle and the rod 3 penetrates, a bottom cap 11 that closes the lower opening in the cylinder 1 in FIG. 1, a bottomed cylindrical holder 4 provided side by side, and a housing A holder / housing composite member H having a portion 5 and an upper end in FIG. 1 of a rod 3 protruding out of the cylinder 1 connected to a bottom portion 4a of the holder portion 4; , A cap 51 for closing the opening of the bladder 50 and the housing part 5, a base valve assembly 6 attached between the holder part 4 and the housing part 5 in the holder housing composite member H, An outer cylinder 7 connected to the cylindrical portion 4b of the holder portion 4 and extending downward from the cylindrical portion 4b in FIG. 1 and into which the cylinder 1 enters and exits, and an outer cylinder 7 connected to the outer cylinder 7 and downward from FIG. And an annular extension member 8 extending.

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

  Further, brackets 4c and 11a are provided at an upper portion in FIG. 1 of the holder portion 4 at both ends in the axial direction of the shock absorber A and a lower portion of the bottom cap 11 in FIG. 1, respectively. Then, 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. Therefore, when an impact due to road surface irregularities is input to the wheels, the rod 3 moves in and out of the cylinder 1 and the damper body D expands and contracts, and the cylinder 1 moves in and out of the air cylinder C and the gas spring expands and contracts. The shock absorber A expands and contracts. The use 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 a thread groove formed on the inner periphery of both ends. The rod guide 10 is screwed into the upper end of the cylinder 1 in FIG. 1, and the bottom cap 11 is screwed into the lower end. 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 partitioned by the piston 2 into two rooms. Of these two chambers, the chamber on the rod 3 side that is compressed when the shock absorber A is extended is referred to as the extension side chamber L1, and the chamber on the piston 2 side that is compressed when contracted is the compression side chamber L2. Each of the extension side chamber L1 and the compression side chamber L2 is filled with a liquid such as hydraulic oil.

  As shown in FIG. 2, the rod guide 10 has a small diameter portion 10a inserted into the cylinder 1 and a piston portion 10b connected to the upper side of the small diameter portion 10a in FIG. 2 and having an outer diameter larger than the outer diameter of the small diameter portion 10a. And the piston portion 10b projects radially outward from the cylinder 1. The piston portion 10b is in sliding contact with the inner periphery of the outer cylinder 7, and partitions 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 later in detail.

  An annular bush 12 is provided on the inner periphery of the rod guide 10, and the rod guide 10 slides on the outer periphery of the rod 3 via the bush 12 to support the rod 3 movably in the axial direction. On the inner periphery of the rod guide 10 and above the bush 12, there is provided an annular gas seal 13 slidably in contact with the outer periphery of the rod 3 to prevent gas in the first air chamber G <b> 1 from entering the cylinder 1. Provided below the bush 12 is 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. In addition, the space between the small diameter portion 10a of the rod guide 10 and the cylinder 1 and the space between the bottom cap 11 (FIG. 1) and the cylinder 1 are closed by unillustrated seals. Therefore, the working chamber L is maintained liquid-tight.

  Further, the rod guide 10 has a pressure release passage 10c that communicates a space K, which 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, to the second air chamber G2. In addition, a check valve 19 is provided which allows only the flow of the liquid flowing from the space K to the second air chamber G2 through the pressure release passage 10c. The check valve 19 shuts off the depressurizing passage 10c by seating the valve body on the valve seat. However, the check valve 19 seals the space between the valve body and the valve seat 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 slides on 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 a portion of the closing member 15 that slides on the outer periphery of the rod 3, and the back surface is supported by the rod guide 10 and the closing member 15. Then, when the rod 3 retreats 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 so that the shock at the time of the maximum extension of the shock absorber A is reduced. ease.

  As shown in FIG. 1, the rod 3 is arranged inside the cylinder 1 while being connected to a main body 3 a supported by a rod guide 10 and a lower side of the main body 3 a in FIG. 1 and having an outer diameter outside the main body 3 a. It has a mounting portion 3b smaller than the diameter, and a connecting portion 3c which is arranged outside the cylinder 1 so as to be connected to the upper side of the main body portion 3a in FIG. 1 and has a thread groove formed on the outer periphery. The connecting portion 3c is connected to the holder portion 4, the main body portion 3a passes through the inside of the outer cylinder 7 and the rod guide 10, and the annular piston 2 is mounted on the outer periphery of the mounting portion 3b. More specifically, a thread groove is formed on the outer periphery of the distal end of the mounting portion 3b, and the piston 2 is provided between the nut 30 screwed to the outer periphery of the distal end and a step formed at the end of the mounting portion 3b. It is sandwiched and fixed.

  The rod 3 is formed with a vertical hole 3d penetrating the center portion in the axial direction, and a horizontal hole 3e opened to the side of the main body 3a near the mounting portion 3b and communicating with the vertical hole 3d. The horizontal hole 3e is closed by the closing member 15 when the shock absorber A is most extended, and communicates with the extension side chamber L1 in a normal stroke range. Further, since the vertical hole 3d is always in communication with the compression side chamber L2, the liquid moves through the rod 3 between the extension side chamber L1 and the compression side chamber L2 in a normal stroke range where the horizontal hole 3e is not closed. it can. In other words, the vertical hole 3d and the horizontal hole 3e constitute a bypass which bypasses the later-described expansion side valve 20 and compression side valve 21 which are laminated on the piston 2, and this bypass is closed when the shock absorber A is fully extended. Blocked at 15. Further, the horizontal hole 3e functions as a throttle and gives resistance to the flow of the liquid moving between the extension side chamber L1 and the compression side chamber L2.

  The piston 2 is formed with an expansion-side passage 2a and a compression-side passage 2b that communicate the expansion-side chamber L1 and the compression-side chamber L2. Further, the expansion valve 20 for opening and closing the outlet of the expansion passage 2a is laminated on the lower side of the piston 2 in FIG. 1, and the compression valve for opening and closing the outlet of the compression passage 2b on the upper side of the piston 2 in FIG. 21 are stacked. The extension side valve 20 and the compression side valve 21 are both leaf valves, and the inner peripheral portion is fixed to the outer periphery of the rod 3 together with the piston 2 with a nut 30 in a state where the outer peripheral side is allowed to bend. Therefore, the expansion side valve 20 can open the expansion side passage 2a when bent under the pressure of the expansion side chamber L1, and the compression side valve 21 can open the compression side passage 2b when bent under the pressure of the compression side chamber L2. In addition, the expansion side valve 20 and the compression side valve 21 are not limited to leaf valves, and can be appropriately changed such as a poppet valve or an orifice.

  Further, on the lower side in FIG. 1 of the expansion side valve 20 and on the upper side of the compression side valve 21, valve stoppers 22 and 23 are respectively laminated. The valve stoppers 22 and 23 come into contact with the rear surface of the valve when the corresponding expansion-side valve 20 or compression-side valve 21 bends by a predetermined amount, and prevents the valve from bending any further, thereby limiting the opening amount of the valve. Further, the valve stopper 23 also serves as a rebound stopper, and abuts against the rebound cushion 16 when the shock absorber A is fully extended, as described above.

  Subsequently, the holder housing composite member H connected to the upper end of the rod 3 in FIG. 1 is cylindrical with a bottom and has a holder portion 4 whose opening is arranged downward in FIG. And a housing part 5 having a bottomed cylindrical shape and an opening arranged 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 has a liquid passage 90 communicating the working chamber L and the reservoir R through the vertical hole 3d, and a gas passage 91 communicating the air cylinder C and the reservoir R. . Further, a base valve assembly 6 is attached to the connection 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.

  A bladder 50 having a bottomed tubular shape and capable of expansion and contraction 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 inside the bladder 50 is formed. . As described above, the reservoir R is a separately-installed tank provided outside the damper body D, and has 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, but 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 gas chamber G3 communicates with the first gas chamber G1 through the gas passage 91. More specifically, the cap 51 is formed in a cylindrical shape with a bottom, and the bottom portion 51a is directed toward the opening side of the housing portion 5 and the cylindrical portion 51b is inserted into the housing portion 5 toward the inside of the housing portion 5. Have been. The bladder 50 is connected to the outer periphery of the distal end of the tubular portion 51b. Further, a plurality of through holes 51c penetrating the thickness of the cylindrical portion 51b is formed in the cylindrical portion 51b of the cap 51 in a 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. Further, the outer periphery of the housing portion 5 on the outside air side with respect to the annular groove 5 a is closed by the seal 52. Accordingly, 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. As a result, the gas in the air chamber G3 can also move into the first air chamber G1 through the above passage in reverse.

  The base valve assembly 6 provided at the connection portion 9 is provided in the middle of the liquid passage 90 and has a partition wall (not shown) for partitioning the working chamber L and the liquid chamber L3. A suction passage 6a and a discharge passage 6b that communicate with the chamber L3; a check valve 60 that allows only the flow of the liquid from the liquid chamber L3 to the working chamber L through the suction passage 6a; A damping valve 61 is provided for providing resistance to the flow of the liquid toward L3 and preventing the flow in the opposite direction.

  As shown in FIG. 1, the holder 4 has a bottom 4a and a tube 4b extending to one side from the outer periphery of the bottom 4a, and the outer tube 7 is screwed onto the inner periphery of the tip of the tube 4b. Is done. The outer diameter of the cylindrical portion 4 b on the bottom 4 a side 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 smaller than the inner diameter of the outer cylinder 7 with which the rod guide 10 slides. Can also be reduced. As described above, in the air cylinder C, if the outer diameter of the portion of the air cylinder C where the rod guide 10 does not slide is smaller than the outer diameter of the sliding portion, even if the outer diameter of the sliding portion, that is, the outer cylinder 7 is increased, When the shock absorber A is mounted on the vehicle body, interference between the shock absorber A and the vehicle body can be avoided and mounting can be facilitated.

  Further, an annular nut portion 4d projecting inward from the cylindrical portion 4b is provided below the bottom portion 4a in FIG. The rod 3 is screwed onto the inner periphery of the nut portion 4d, and the rod 3 is prevented from loosening by using the 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 to reduce the shock of the shock absorber A during the most contraction. 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 tube 7 in FIG. 1 is screwed to the inner periphery of the holder portion 4, and the lower end in FIG. 1 is screwed to the inner periphery of the extension member 8. The piston portion 10b of the rod guide 10 slides. As shown in FIG. 2, an annular bush 17 is provided on the outer circumference of the piston portion 10 b, and the rod guide 10 slides on the inner circumference of the outer cylinder 7 via the bush 17. 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 vertically, and the gap between the rod guide 10 and the outer cylinder 7 is closed by the seal 18, The space between the outer cylinder 7 and the holder 4 is closed by a seal 70 (FIG. 1). A gas such as air is sealed in a 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 the portion serves as a 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. Conversely, when the shock absorber A extends, the cylinder 1 retreats from the air cylinder C and the air cylinder C rises with respect to the rod guide 10, so that the volume of the first air chamber G1 increases and the first air chamber G1 expands. The pressure in G1 decreases. As described above, the rod guide 10 functions as an air piston that compresses the gas in the first air chamber G1, and the main spring S1, which has the air cylinder C, the rod guide 10, and the first air chamber G1, and is a gas spring. Be 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 elastically deform 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 first air chamber G1 and the pressure in the air chamber G3 are equal, and the air chamber G3 also forms the main spring S1 together with the first air chamber G1. Although not shown, a gas supply / discharge passage opening outside the connection portion 9 is connected to the gas passage 91, and an air valve is attached to an open end of the gas supply / discharge passage. Therefore, gas can be supplied and exhausted into the first air chamber G1 and the air chamber G3 via the air valve, these pressures can be simultaneously changed, and the elastic force of the main spring S1 can be adjusted.

  Subsequently, as shown in FIG. 2, the extension member 8 has an annular bottom portion 8a that allows the cylinder 1 to pass therethrough, and a tubular portion 8b that extends upward from the outer periphery of the bottom portion 8a in FIG. 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 portion 8a, and the extension member 8 slides on the outer periphery of the cylinder 1 via the bush 80. Further, annular seals 81 and 82 are provided on the inner periphery of the bottom portion 8a and below the bush 80 in FIG. 2 so as to slidably contact the outer periphery of the cylinder 1, and seals 81 and 82 are provided between the extension member 8 and the cylinder 1. At the same time, the space between the outer cylinder 7 and the extension member 8 is closed by the seal 83. Further, a gas such as air is sealed in a space on the outer periphery of the cylinder 1 and surrounded by the outer cylinder 7, the extension member 8, and the piston portion 10b of the rod guide 10, and the portion is defined as the second air chamber G2. It has been 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 expands and the inside of the second air chamber G2 increases. Pressure becomes lower. Conversely, when the shock absorber A extends, the cylinder 1 retreats from the air cylinder C and the air cylinder C rises 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. As described above, 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 moves the damper body D in the contracting direction, opposite to the main spring S1. To energize.

  The extension member 8 is formed with a gas supply / discharge passage 8c (FIG. 2) penetrating the bottom 8a at an angle, and an air valve 84 is attached to the gas supply / discharge passage 8c. Therefore, gas can be supplied to and exhausted from the second air chamber G2 via the air valve 84 to change the pressure in the second air chamber G2 and adjust the elastic force of the balance spring S2. 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 of urging the damper body D is opposite, so that when the shock absorber A is mounted on the vehicle, the riding comfort of the vehicle is improved. Can be good. More specifically, the vehicle body can be elastically supported only by the main spring S1, but in this case, the spring characteristics of the shock absorber as a whole are the characteristics of only the main spring S1. Since the main spring S1 is a gas spring, the spring characteristic is a non-linear characteristic. If the spring characteristics of the shock absorber are set in accordance with the desired characteristics in the latter half of the stroke, which is the most contracted side, the elastic force in the first half of the stroke, particularly in the vicinity of the maximum extension, becomes excessive, deteriorating ride 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 riding comfort of the vehicle, the elastic force acting in the extension direction of the main spring S1 when the shock absorber A is at the maximum extension is offset by the balance spring S2, and the spring characteristics and balance of the main spring S1 are balanced. It is preferable that the combined characteristic of the spring characteristics of the spring S2 is approximated to the characteristic of the coil spring by approaching 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 retreats from the cylinder 1 and the cylinder 1 retreats from the air cylinder C and the shock absorber A extends, the piston 2 moves upward in FIG. 1 in the cylinder 1 and the extension side chamber L1 is compressed, The compression side chamber L2 expands. Then, the pressure in the expansion side chamber L1 to be compressed increases, 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 withdrawn rod volume is insufficient, but the check valve 60 is opened and the liquid corresponding to the insufficient amount is supplied from the liquid chamber L 3 to the pressure side chamber L 2 through the suction passage 6 a. Since resistance is given to the flow of the liquid from the expansion side chamber L1 to the compression side chamber L2 by the expansion side valve 20, the pressure in the expansion side chamber L1 increases. 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 is generated between the pressure in the expansion side chamber L1 and the pressure in the compression side chamber L2, and this differential pressure acts on the piston 2 so that the damper exerts a damping force that hinders the expansion operation of the shock absorber A.

  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 increases and the volume of the second air chamber G2 decreases. Further, when the shock absorber A is extended, the liquid corresponding to the rod volume retreating from the cylinder 1 flows out of the liquid chamber L3, so that the bladder 50 expands and the volume of the air chamber G3 expands accordingly. Therefore, when the shock absorber A extends, the elastic force of the main spring S1 having the first air chamber G1 and the air chamber G3 decreases, and the balance spring having the second air chamber G2. The elastic force of S2 increases, and the force for pushing up the vehicle body as the entire shock absorber A decreases.

  Conversely, 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 the cylinder 1 in FIG. It is compressed and the extension side chamber L1 expands. Then, the pressure in the compression-side chamber L2 to be compressed increases, and the liquid in the compression-side chamber L2 pushes and opens the compression-side valve 21, passes through the compression-side passage 2b, and moves to the expansion-side chamber L1. In the cylinder 1, the liquid corresponding to the volume of the rod that has entered becomes excessive, but this excess liquid pushes open the damping valve 61, passes through the discharge passage 6b, and moves to the liquid chamber L3. Since the resistance of the liquid flowing from the compression side chamber L2 to the expansion side chamber L1 and the liquid chamber L3 is given by the compression side valve 21 and the damping valve 61, the pressure in the compression side chamber L2 increases. On the other hand, the expanding pressure in the extension side chamber L1 decreases. Therefore, a difference is generated between the pressure in the compression side chamber L2 and the pressure in the expansion side chamber L1, and this differential pressure acts on the piston 2 so that the damper exerts a damping force that impedes the contraction operation of the shock absorber A.

  When the shock absorber A is contracted, 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 expanded. Further, when the shock absorber A is contracted, the liquid corresponding to the rod volume entering the cylinder 1 flows into the liquid chamber L3, so that the bladder 50 is reduced and the volume of the air chamber G3 is reduced accordingly. Accordingly, when the shock absorber A contracts, the elastic force of the main spring S1 having the first air chamber G1 and the air chamber G3 increases, and the balance spring having the second air chamber G2. The elastic force of S2 decreases, and the force for pushing up the vehicle body as the entire shock absorber A increases.

  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, when the shock absorber A expands and contracts, a part of the liquid moving between the extension side chamber L1 and the compression side chamber L2 bypasses the extension side passage 2a and the compression side passage 2b, and passes through the horizontal hole 3e and the vertical hole 3d. Through the configured bypass. However, when the shock absorber A extends beyond the normal stroke range, the lateral hole 3e provided in the rod 3 is closed by the closing member 15, so that the bypass passage is cut off. Then, the flow rate of the liquid passing through the extension side valve 20 increases, so that the damping force increases, and the extension operation of the shock absorber A can be suppressed by 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, thereby suppressing the extension operation of the shock absorber A. As described above, in the shock absorber A, the expansion of the shock absorber A beyond the normal stroke range can be suppressed by both the blocking of the bypass path by the closing member 15 and the rebound cushion 16, so that when the shock absorber A is fully extended. It has a high effect of reducing shock. However, one of the lateral hole 3e and the rebound cushion 16 may be omitted.

  Conversely, when the shock absorber A contracts beyond the normal stroke range, the bump cushion 32 is compressed by the rod guide 10 and exerts an elastic force, thereby suppressing the contraction operation of the shock absorber A.

  When the shock absorber A contracts the 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, but the first air chamber G1 passes through the gas passage 91. It is connected to the air chamber G3 of the reservoir R. Since the main spring S1 is configured to include the first air chamber G1 and the air chamber G3, the volume of the air chamber forming the main spring S1 can be ensured, and the compression ratio can be prevented from becoming excessive. . Therefore, even if the shock absorber A contracts the 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 pressure in the seals 13, 18, 70 and the like becomes large. Load can be prevented.

  Further, even if the buffer A repeatedly expands and contracts and the liquid is accumulated in the space K and the pressure in the space K rises, if the pressure in the space K exceeds the pressure in the second air chamber G2, the check valve 19 is activated. Then, the liquid in the space K moves to the second air chamber G2 through the pressure release passage 10c. Specifically, the pressure in the second air chamber G2 decreases as the shock absorber A contracts, and drops to near the 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 buffer A contracts to near the maximum contraction and exceeds the pressure in the second air chamber G2, the check valve 19 is opened and the liquid in the space K is discharged. After moving to the second air chamber G2, the pressure in the space K decreases to the pressure in the second air chamber G2. Further, when 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 operation and effect of the shock absorber A according to the present embodiment will be described.

  In the present embodiment, the outer diameter of the air cylinder C at the upper end (the end opposite to the cylinder side) in FIG. 1 is formed smaller than the outer diameter at the lower side (cylinder 1 side). For this reason, even if the outer diameter of the portion (the outer cylinder 7) of the air cylinder C where the rod guide 10 slides is increased, when the shock absorber A is attached to the vehicle body, the air cylinder C interferes with peripheral parts of the shock absorber A. Can be prevented and mounting becomes easy. Further, in the air cylinder C, when the outer diameter of the portion where the rod guide 10 slides is increased, the inner diameter is increased accordingly, and the outer diameter of the rod guide 10 as an air piston can be increased. As described above, when the outer diameter of the rod guide 10 is increased, the area of the pressure receiving surface of the rod guide 10 that receives the pressure of the first air chamber G1 (the pressure receiving area) 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 (seals 13, 18, 70, 82, 81, etc.) that prevent the gas sealed in these air chambers 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. In the shock absorber A, the air cylinder C is constructed by assembling the holder 4, the outer cylinder 7, and the extension member 8 of the holder housing composite member H formed separately. Any or all of the cylinder 7 and the extension member 8 may be integrally formed as one component.

  In the present embodiment, the shock absorber A is provided outside the first air chamber G1 and has a reservoir L3 communicating with the working chamber L and an air chamber G3 communicating with the first air chamber G1. R is provided. According to this configuration, the air chamber G3 of the reservoir R provided outside the first air chamber G1 also forms the main spring S1 together with the first air chamber G1. The reservoir R is a member necessary for compensating for a volume change in the cylinder corresponding to the rod volume going into and out of the cylinder 1 and a volume change due to a temperature change of the liquid contained in the cylinder 1. That is, in the shock absorber A, such an air chamber G3 of the reservoir R is also used as an air chamber forming the main spring S1, and therefore, even if the volume of the air chamber forming the main spring S1 is secured, the buffer chamber A3 does not have a shock absorbing capacity. An increase in the weight of the container 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 excessively large, the weight of the shock absorber A is suppressed from becoming heavy, and the main spring S1 is gaseous. The effect of weight reduction by using a spring can be sufficiently obtained.

  The first air chamber G1 and the air chamber G3 of the reservoir R may be separated from each other, and the air chamber forming the main spring S1 may be composed of only the first air chamber G1. 1 may be connected to the lower middle portion. 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 the liquid chamber L3 and the 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 communicate with each other through the passage, the passage of the passage is easy.

  Here, when the reservoir R is connected to the bottom cap 11 side of the cylinder 1, it is necessary to take care that the reservoir and the air cylinder do not interfere when the shock absorber expands and contracts, and the outer diameter of the air cylinder is limited by the reservoir. May be done. However, according to the above configuration, there is no fear of 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 as 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 (seals 13, 18, 70, 82, 81, etc.) that prevent the gas sealed in these air chambers from flowing out.

  Further, according to the above configuration, since the reservoir R is a tank externally attached to the damper body D and is connected to the air cylinder C, even if the reservoir R is provided outside the first air chamber G1. The size of the reservoir R can be reduced without increasing the size of the reservoir R. Further, 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, so that the mountability to the vehicle can be improved. The term “side-by-side arrangement” 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 mounted. It may be inclined to.

  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. 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 of the reservoir R and the first air chamber G1 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 the rod 3 is formed with a vertical hole (passage) 3d that connects the working chamber L and the liquid chamber L3. For this reason, when connecting the reservoir R to the air cylinder C, it is not necessary to add a member for forming a passage communicating the liquid chamber L3 and the working chamber L outside the damper main body D. And the configuration of the shock absorber A can be simplified. Note that a passage that connects the liquid chamber L3 and the working chamber L may be provided outside the damper body D, and the configuration of the passage that connects the liquid chamber L3 and the working chamber L can be appropriately changed. The change can be made without depending on the shape and configuration of the air cylinder C and the communication / cutoff between the first air chamber G1 and the air chamber G3.

  Further, in the present embodiment, the tip of the air valve 84 provided in the gas supply / discharge passage 8c for supplying / discharging gas to / from the second air chamber G2 is disposed so as to protrude into the second air chamber G2. For this reason, even if the liquid discharged from the space K accumulates in the second air chamber G2, the tip of the air valve 84 protrudes from the liquid level. Therefore, when the gas in the second air chamber G2 is extracted from the gas supply / discharge passage 8c, the liquid does not leak from the air valve 84. Further, when gas is supplied from the gas supply / discharge path 8c into the second air chamber G2, the liquid in the second air chamber G2 does not bubble. The arrangement of the air valve 84 is not limited to that shown in the figure, but can be changed as appropriate. The change can be made regardless of the shape and configuration of the air cylinder C, the communication between the first air chamber G1 and the air chamber G3, and the configuration of the passage for communicating the liquid chamber L3 and the working chamber L. It is.

  In the present embodiment, the shock absorber A has a cylinder 1 in which a working chamber L in which a liquid is stored is formed, and the shock absorber A is movably inserted into the cylinder 1 to move the working chamber L to the extension side chamber (room). A) a piston 2 partitioned into L1 and a pressure side chamber (room) L2, a rod 3 connected to the piston 2 and extending outward from the cylinder 1, and a cylinder 1 connected to the rod 3 and movably inserted inside. An air cylinder C, a first air chamber G1 on the rod 3 side and a second air chamber G2 on the cylinder 1 side, which are connected to the cylinder 1 and movably support the rod 3 and in which gas is sealed in the air cylinder C. An annular rod guide 10 defined on the inner periphery of the rod guide 10, a liquid seal 14 slidably in contact with the outer periphery of the rod 3 to maintain the working chamber L in a liquid-tight manner, and an inner periphery of the rod guide 10. A liquid seal 1 1 (on the first air chamber G1 side) in FIG. 1, which is in sliding contact with the outer periphery of the rod 3, the gas seal 13 for keeping the first air chamber G1 airtight, and the inner periphery of the rod guide 10. A pressure release passage 10c that communicates a space K formed between the liquid seal 14 and the gas seal 13 with the second air chamber G2, and a pressure release passage 10c provided from the space K to the second air chamber G2. A check valve 19 that allows only liquid flow.

  According to the above configuration, the main spring S1, which 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 when the main spring S1 which is a gas spring is provided, when the pressure in the space K becomes higher than the pressure in the second air chamber G2, the check valve 19 is opened, and the pressure in the space K is reduced to the second pressure. It can escape to the air chamber G2. Therefore, since the inside of the space K can be prevented from becoming high pressure, the back surface (the side of the space K) of the gas seal 13 is pushed by the pressure in the space K, and the sealing property of the gas seal 13 is reduced. The gas in the air chamber G1 can be prevented from entering the cylinder 1. Since the gas can be prevented from entering the cylinder 1, the response of the damper A to the damping force generation can be maintained satisfactorily.

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

  Further, according to the above configuration, the balance spring S2 is provided with the second air chamber G2, and the balance spring S2 helps the shock absorber A to contract in the vicinity of the maximum extension. Therefore, when the shock absorber A is mounted on the vehicle, the ride comfort of the vehicle can be improved. Further, since both the main spring S1 and the balance spring S2 are gas springs, not only the weight can be reduced, but also the spring characteristics of the shock absorber A as a whole are less likely to be affected by temperature changes.

  This is because, for example, when the shock absorber A is heated, the temperatures in the first air chamber G1 and the second air chamber G2 increase, the pressures in the first air chamber G1 and the second air chamber G2 increase, and the main spring Although the elastic force of S1 and the balance spring S2 increases, as described above, the elastic force of the main spring S1 acts in the direction of extending the damper body D, while the elastic force of the balance spring S2 acts on the damper body D. This is because it acts in the contracting direction, so that the increase in the elastic force of the main spring S1 and the increase in the elastic force of the balance spring S2 cancel each other. In particular, when the shock absorber A is a rear cushion unit as in the present embodiment, it is disposed near the engine and heated 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 the spring and the gas spring may constitute a balance spring. Such changes include the shape and configuration of the air cylinder C, the communication / blocking between the first air chamber G1 and the air chamber G3, the configuration of the passage for communicating the liquid chamber L3 with the working chamber L, and the configuration of the air valve 84. This is possible regardless of the arrangement and the type and configuration of the valve provided in the pressure release passage 10c.

  As described above, the preferred embodiments of the present invention have been described in detail, but alterations, modifications, and changes are possible 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: Compression side chamber (room), 1: Cylinder, 2: Piston, 3: Rod, 10: Rod guide, 10c: Depressurization passage, 13. ..Seal for gas, 14 ... Seal for liquid, 19 ... Check valve (valve)

Claims (1)

A cylinder in which a working chamber containing a liquid is formed, and
A piston movably inserted into the cylinder to partition the working chamber into two chambers;
A rod connected to the piston and extending outward from the cylinder;
An air cylinder connected to the rod and movably inserted into the cylinder inside;
An annular rod guide connected to the cylinder to movably support the rod and partitioning 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 that is provided on the inner periphery of the rod guide and slidably contacts the outer periphery of the rod, and maintains the working chamber in a liquid-tight manner;
A gas seal that is provided on the inner periphery of the rod guide and 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 pressure release passage communicating the space formed between the liquid seal and the gas seal on the inner periphery of the rod guide to the second air chamber,
And a valve provided in the depressurizing passage and allowing only a flow of liquid from the space to the second air chamber.

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