JP6274925B2 - Shock absorber - Google Patents

Description

  The present invention relates to a shock absorber.

  In general, a shock absorber is interposed between a vehicle body and a wheel in a vehicle, so that an impact caused by road surface unevenness is mitigated to improve the riding comfort of the vehicle.

  For example, as disclosed in Patent Documents 1 and 2, a shock absorber used for a front fork that suspends a front wheel of a motorcycle includes a telescopic type including an outer tube and an inner tube for the purpose of improving performance. An erecting hydraulic damper that exhibits damping force is built into the tube member, and the outer periphery of the rod in the damper is sealed with a sealing member to improve the sealing inside the cylinder and held in the upper opening of the cylinder In some cases, a relief valve is provided on the head member that holds the seal member, and the gas deposited in the cylinder when the relief valve is opened can be discharged out of the cylinder.

JP 2003-247484 A JP-A-10-292842

  In order to realize the gas discharge mechanism as described above, as shown in FIG. 3A, the head member 3A disclosed in Japanese Patent Application Laid-Open No. 2003-247484 has an annular shape in which a passage 301 communicating between the inside and the outside of the cylinder 1 is formed. Between the valve seat 300, a relief valve formed by an annular plate-like leaf valve 302 that is stacked on the valve seat 300 and opens and closes the passage 301, and a cylinder 1 that is screwed into the outer periphery of the upper opening of the cylinder 1. It comprises a seat 300 and a cylinder head 303 that is fixed by sandwiching the outer periphery of the leaf valve 302. An annular bearing 4 that pivotally supports the rod 2 and an outer periphery of the rod 2 are provided on the inner periphery of the valve seat 300. The seal member 500 that seals the upper and lower sides is held in series.

  A locking surface a is formed on the inner periphery of the cylinder portion 303b of the cylinder head 303 formed in a cap shape, and a locking step portion b is formed on the outer periphery of the valve seat 300 to face the locking surface a. Since the axial force when the cylinder head 303 is screwed into the cylinder 1 is received by the locking step b, the outer periphery of the leaf valve 302 enters the gap formed between the top 303a of the cylinder head 303 and the valve seat 300. As a result, no axial force is applied to the leaf valve 302.

  However, in this case, there is a problem that the cracking pressure of the leaf valve 302 varies due to the variation of the gap into which the outer peripheral portion of the leaf valve 302 is inserted. Further, since the seal member 500 and the bearing 4 are held in series in the valve seat 300, the axial length of the valve seat 300 is increased. Since the leaf valve 302 and the cylinder head 303 are further overlapped with the valve seat 300, the end surface (valve seat) facing the inside of the cylinder 1 in the head member 3A from the upper end of the head member 3A (the upper end of the cylinder head 303). There is a problem that the length X up to the lower end of 300 becomes longer and the head member 3A becomes bulky in the axial direction.

  Further, as shown in FIG. 3B, the head member 3B disclosed in FIG. 1 of Japanese Patent Laid-Open No. 10-292842 is screwed into the inner periphery of the upper opening of the cylinder 1, and the bearing 4 and the seal member 500 are provided on the inner periphery. Is formed from the bottom 310b of the guide member 310 to the valve seat 311 and the annular valve seat 311 inserted into the cylindrical portion 310a of the guide member 310. A passage 312 communicating between the inside and the outside of the cylinder 1, a relief valve formed of an annular plate-like leaf valve 313 stacked on the valve seat 311 to open and close the passage 312, and an upper inner periphery of the cylindrical portion 310 a of the guide member 310 are screwed together. A cylinder head 314 is fixed by sandwiching the outer periphery of the valve seat 311 and the leaf valve 313 between the bottom 310b of the guide member 310. It is configured to include a.

  According to the above configuration, since the axial force when the cylinder head 314 is screwed into the guide member 310 can be stably applied to the leaf valve 313, it is possible to suppress variation in the cracking pressure of the leaf valve 313. However, since the guide member 310 holds the seal member 500 and the bearing 4 in series in the vertical direction, the axial length of the guide member 310 is increased. Since the valve seat 311, the leaf valve 313, and the cylinder head 314 are further stacked on the guide member 310, the head member 3 </ b> B faces the cylinder 1 from the upper end (the upper end of the cylinder head 314). The length X to the end surface (the lower end of the guide member 310) is further increased, and the problem that the head member 3B is bulky in the axial direction cannot be solved.

  Accordingly, an object of the present invention is to provide a shock absorber capable of suppressing variation in cracking pressure of a leaf valve that functions as a relief valve and making the head member compact.

Means for solving the above-mentioned problems include a cylinder connected to the wheel side and containing a liquid, a rod connected to the vehicle body side and inserted into the cylinder so as to be movable in the axial direction, and an upper opening of the cylinder a head member attached to the rod penetrates the parts, an annular bearing for supporting the rod is held in the head member, an annular sealing member for sealing the outer periphery of the rod is held in the head member When equipped with a reservoir formed outside the cylinder liquid is stored, the head member, the inner annular top portion for holding the bearing in the circumferential and cylindrical tubular portion extending cylinder side from the top preparative a cylinder head which is formed in the cap shape provided with an annular valve seat for holding the inner circumference to the sealing member is screwed to an inner periphery of the tubular portion, formed in the valve seat Is to open and close the passage communicating with the said reservoir in said cylinder, said passage while being sandwiched the inner periphery or the outer periphery between the cylinder head and the valve seat with the bearing is inserted inside An annular plate-like leaf valve.

  According to the present invention, since the axial force when the valve seat is screwed into the cylinder head is stably applied to the leaf valve that functions as a relief valve, it is possible to suppress variations in cracking pressure of the leaf valve.

  Furthermore, since the length from the upper end of the cylinder head, which is the upper end of the head member, to the lower end of the valve seat, which is the end surface facing the cylinder in the head member, can be shortened, the head member can be made compact. It becomes possible.

It is the front view which notched and showed the principal part of the buffer which concerns on one embodiment of this invention. It is the figure which expanded and showed a part of FIG. (A) is the longitudinal cross-sectional view which showed the principal part of the conventional shock absorber partially. (B) is the longitudinal cross-sectional view which showed partially the principal part of the other conventional shock absorber.

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

  As shown in FIG. 1, a shock absorber A according to the present embodiment is connected to a wheel side and accommodates a liquid, and is connected to a vehicle body side and inserted into the cylinder 1 so as to be movable in the axial direction. Rod 2 that is attached to the upper opening of the cylinder 1 and through which the rod 2 passes, an annular bearing 4 that is supported by the head member 3 and pivotally supports the rod 2, and An annular sealing member 5 that is held by the head member 3 and seals the outer periphery of the rod 2 and a reservoir R that is formed outside the cylinder 1 and stores liquid are provided.

  The head member 3 includes an annular top portion 30a that holds the bearing 4 on the inner periphery, and a cylindrical tube portion 30b that extends from the top portion 30a toward the cylinder 1 and is formed into a cap shape. And an annular valve seat 31 that is screwed into the inner periphery of the cylindrical portion 30b and holds the sealing member 5 on the inner periphery, and the inside of the cylinder 1 and the reservoir R that are formed in the valve seat 31 communicate with each other. And an annular plate-like leaf valve 32 that opens and closes the passage 31a while sandwiching an inner peripheral portion between the cylinder head 30 and the valve seat 31.

  Hereinafter, in detail, in the present embodiment, the shock absorber A according to the present invention is used in a front fork that suspends a front wheel in a straddle-type vehicle such as a motorcycle. Since the configuration of the front fork is well known, detailed illustration is omitted, but a pair of shock absorbers (only one shock absorber A is shown and the other shock absorber is omitted) that supports the front wheel from both sides, and these A shock absorber A is connected to a vehicle body side bracket (not shown) connected to a vehicle body frame which is a skeleton of the vehicle body, and a wheel side bracket B which connects each shock absorber A to the front axle. The present invention is embodied in one or both of the shock absorbers A. Hereinafter, the configuration of the shock absorber A in which the present invention is embodied will be described in detail. The shock absorber A according to the present invention may be used as a shock absorber other than the front fork. For example, the shock absorber A may be used as a rear cushion for suspending a rear wheel of a saddle type vehicle.

  The shock absorber A includes a telescopic tube member T that is an outer shell of the shock absorber A, an upright damper D that is housed in the tube member T and generates a damping force, and the tube member T and the damper D. And a suspension spring S which is provided in a reservoir R formed between the two and elastically supports the vehicle body. A liquid is stored in the reservoir R to form a liquid storage chamber, and an air chamber is formed by enclosing a gas on the upper side through a liquid surface (not shown) of the liquid. In the present embodiment, the suspension spring S is formed of a coil spring. However, the suspension spring S may be sealed while compressing gas in the air chamber, and the compressed gas may be used as an air spring.

  The tube member T is a telescopic type including an outer tube t1 connected to a vehicle body side bracket (not shown) and an inner tube t2 connected to the wheel side bracket B and going into and out of the outer tube t1. When an impact is input to the wheel, the inner tube t2 enters and exits the outer tube t1, and the shock absorber A is expanded and contracted.

  The upper end opening of the tube member T is closed by a cap member (not shown) that is an upper sealing member, and the lower opening of the tube member T is a cylindrical wheel side bracket that constitutes the lower sealing member. B and a bottom cap C inserted from below the wheel side bracket B are closed. Further, the lower opening of the cylindrical gap formed between the overlapping portions of the outer tube t1 and the inner tube t2 is an annular oil that is held on the lower inner periphery of the outer tube t1 and is in sliding contact with the outer peripheral surface of the inner tube t2. Sealed with the seal OS and the dust seal DS. For this reason, the liquid and gas accommodated in the tube member T are prevented from leaking out of the tube member T.

  The damper D accommodated in the tube member T is set upright, and is inserted into the cylindrical cylinder 1 standing at the axial center portion of the inner tube t2 and movably in the axial direction. Rod 2, a head member 3 that is attached to the upper opening of the cylinder 1 and through which the rod 2 passes, an annular bearing 4 that is slidably contacted with the outer peripheral surface of the rod 2 and is held in series by the head member 3 A seal member 5, an annular piston 6 that is held on the outer periphery of the lower end of the rod 2 and slidably contacts the inner peripheral surface of the cylinder 1, and a base rod 7 that is screwed into the inner periphery of the lower opening of the cylinder 1. And an annular base member 8 held on the outer periphery of the upper end portion of the shaft portion 7b extending upward from the center of the base portion 7a of the base rod 7. The cylinder 1 is connected to a wheel side bracket B via a base rod 7 and a bottom cap C, and the rod 2 is connected to a vehicle body side bracket via a cap member (not shown) and an outer tube t1. (Not shown).

In the cylinder 1, an upper extension side chamber L <b> 1 and a lower pressure side chamber L <b> 2 defined by the piston 6 and filled with liquid, and an intermediate chamber L <b> 3 defined by the base member 8 and the pressure side chamber L <b> 2 are formed. . A hole 1a that penetrates the thickness of the cylinder 1 and communicates with the inside and outside of the cylinder 1 is formed below the base member 8 and above the base portion 7a of the base rod 7 in the cylinder 1. a liquid reservoir chamber of the reservoir R is in communication at all times with each other via the hole 1 a.

  The rod 2 includes a cylindrical rod body 20 and a center rod 21 which is connected to the lower side of the rod body 20 and holds the piston 6 on the outer periphery. The center rod 21 is formed with a center rod passage 21a that opens to the extension side chamber L1 and continues to the inside of the rod body 20. The center rod passage 21a is formed on the rod body passage inside the rod body 20. 20a and a cap member passage formed in a cap member (not shown) and opened to the reservoir R constitute a bypass passage 23 that communicates the extension side chamber L1 and the reservoir R. This bypass passage 23 is a one-way passage in which only the flow of liquid from the extension side chamber L1 to the reservoir R is allowed, and in the middle of the bypass passage 23, although not shown, the liquid flowing through the bypass passage 23 An electromagnetic valve is provided for controlling the flow rate.

  The piston 6 is held by the rod 2 and can move in the axial direction in the cylinder 1, and the piston 6 has an extension side piston passage 6a and a pressure side piston passage 6b communicating the extension side chamber L1 and the pressure side chamber L2. Is formed. A leaf valve 60 that opens and closes the expansion side piston passage 6a is stacked below the piston 6, and the leaf valve 60 opens the expansion side piston passage 6a only during the extension operation. Further, a leaf valve 61 for opening and closing the pressure side piston passage 6b is laminated on the upper side of the piston 6, and the leaf valve 61 opens the pressure side piston passage 6b only during the compression operation.

  In the present embodiment, the cracking pressures of the lower leaf valve 60 that opens and closes the expansion-side piston passage 6a and the upper leaf valve 61 that opens and closes the compression-side piston passage 6b are set to be relatively high. , 61 are set to function as damping valves. The setting of the leaf valves 60 and 61 for opening and closing the expansion side piston passage 6a and the pressure side piston passage 6b can be appropriately changed according to the characteristics of the desired damping force. A poppet valve may be substituted for the leaf valves 60 and 61 as valve bodies for opening and closing the piston passages 6a and 6b on the expansion side and the pressure side, and an orifice is provided as a configuration for giving resistance to the flow of liquid. It may be used.

  The base member 8 attached to the lower inner side of the cylinder 1 is formed with an extension side base passage 8a and a pressure side base passage 8b communicating the pressure side chamber L2 and the intermediate chamber L3. On the upper side of the base member 8, a leaf valve 80 that opens and closes the extension-side base passage 8a is stacked, and the leaf valve 80 opens the extension-side base passage 8a only during the extension operation. Further, a leaf valve 81 for opening and closing the pressure side base passage 8b is stacked below the base member 8, and the leaf valve 81 opens the pressure side base passage 8b only during the compression operation.

  In the present embodiment, the cracking pressure of the upper leaf valve 80 that opens and closes the extension-side base passage 8a is set to be relatively low, and the leaf valve 80 is set to function as a check valve. On the other hand, the cracking pressure of the lower leaf valve 81 that opens and closes the pressure-side base passage 8b is set to be relatively high, and is set so that the leaf valve 81 functions as a damping valve. The setting of the leaf valves 80 and 81 for opening and closing the extension-side base passage 8a and the pressure-side base passage 8b can be changed as appropriate according to the desired damping force characteristics. A poppet valve may be substituted for the leaf valves 80 and 81 as valve bodies for opening and closing the base passages 8a and 8b on the expansion side and the pressure side, and an orifice is provided as a configuration for giving resistance to the flow of liquid. It may be used.

  As shown in FIGS. 1 and 2, the head member 3 attached to the upper opening of the cylinder 1 includes a cap-shaped (top cylinder-shaped) cylinder head 30 including an annular top 30 a and a cylindrical cylinder 30 b. An annular collar 33 inserted inside the top portion 30 a of the cylinder head 30, an annular valve seat 31 screwed into the inner periphery of the cylinder portion 30 b of the cylinder head 30, and a stack on the valve seat 31. An annular plate-like leaf valve 32 and an annular spacer 34 laminated on the upper side of the leaf valve 32, and between the top 30 a of the cylinder head 30 and the valve seat 31, The collar 33, the spacer 34, and the inner peripheral portion of the leaf valve 32 can be sandwiched and fixed.

  Further, since the bearing 4 is press-fitted and fixed inside the collar 33 and the seal member 5 is lightly press-fitted inside the valve seat 31, when the valve seat 31 is screwed into the cylinder head 30, the bearing 4 is fitted. The collar 33, the cylinder head 30, the spacer 34, the leaf valve 32, and the valve seat 31 into which the seal member 5 is lightly press-fitted are integrated as the head member 3. At this time, the bearing 4 is supported by the cylinder head 30 and the seal member 5 is held by the valve seat 31. In the head member 3, the member supporting the bearing 4 and the member holding the seal member 5 are separated. . According to this configuration, even if the bearing 4 and the seal member 5 are arranged in series in the vertical direction, the valve seat that serves as an end surface facing the inside of the cylinder 1 in the head member 3 from the upper end of the cylinder head 30 that is the upper end of the head member 3. Since the length X to the lower end of 31 can be shortened to prevent the head member 3 from being bulky in the axial direction, the head member 3 can be made compact.

  Further, the head member 3 integrated as described above is placed on the cylinder 1 from above the spring seat washer 10 that overlaps the upper end of the cylinder 1, and the upper opening of the cylinder 1 is formed on the inner periphery of the cylinder portion 30 b of the cylinder head 30. By screwing, the head member 3 can be attached to the upper opening of the cylinder 1, and the assembly work of the head member 3, the bearing 4 and the seal member 5 can be facilitated.

  As shown in FIG. 2, the cylinder head 30 is formed in a cap shape including an annular top portion 30a and a cylindrical tube portion 30b extending downward from the outer peripheral portion of the top portion 30a. And while the rod main body 20 of the rod 2 is penetrated inside the top part 30a and the cylinder part 30b, the cyclic | annular spring seat SS which supports the suspension spring S is fitted to the outer side of the top part 30a. In the present embodiment, the cylinder head 30 is made of aluminum, which can reduce the weight, but the material of the cylinder head 30 can be changed as appropriate.

  The outer periphery of the top portion 30a of the cylinder head 30 partially protrudes in the radial direction, and the liquid in the reservoir R moves up and down through the gap formed between the protrusions 30c and the spring seat SS. It can be done. An annular step surface 30d is formed on the inner periphery of the top portion 30a so that the inner diameter below the step surface 30d of the top portion 30a is larger than the upper inner diameter. In the top portion 30a, a collar 33 to which the bearing 4 is press-fitted and fixed is inserted on the inner side below the step surface 30d.

  In the present embodiment, the collar 33 is made of steel and has a structure in which the bearing 4 is not directly inserted into the cylinder head 30. However, depending on the material of the cylinder head 30, the bearing 4 may be directly inserted into the cylinder head 30. Also good.

  The bearing 4 is formed in an annular shape, is in sliding contact with the outer peripheral surface of the rod main body 20 inserted inside thereof, and supports the rod 2 so as to be movable in the axial direction. The bearing 4 is set so that the lower portion 4a protrudes from the collar 33 and the top portion 30a of the cylinder head 30 when assembled, and a spacer 34 and a leaf valve 32 are provided on the outer periphery of the protruding lower portion 4a. The bearing 4 also functions as a support member that supports the inner periphery of the spacer 34 and the leaf valve 32. According to this configuration, the bearing 4, the spacer 34 and the leaf valve 32 can be overlapped in the axial direction, and the assembly length of the bearing 4, the spacer 34 and the leaf valve 32 is reduced to the length of the bearing 4. it can. Therefore, even if the bearing 4 is lengthened so that the rod 2 can be supported more stably, the end surface of the head member 3 facing the inside of the cylinder 1 from the upper end of the head member 3 (the upper end of the cylinder head 30) ( It can suppress that the length X to the lower end of the valve seat 31 becomes long.

  In the upper part of the cylinder part 30b in the cylinder head 30, a hole 30e that penetrates the thickness of the cylinder part 30b and communicates the inside and outside of the cylinder part 30b is formed. Further, an annular step surface 30f is also formed on the inner periphery of the cylindrical portion 30b, and is formed such that the inner diameter below the step surface 30f in the cylindrical portion 30b is larger than the upper inner diameter. Screw grooves are formed on both the upper and lower inner peripheries of 30f. And in the cylinder part 30b of the cylinder head 30, the valve seat 31 is screwed to the inner periphery above the step surface 30f, and the valve seat 31 is interposed via the leaf valve 32, the spacer 34 and the collar 33. It is positioned by abutting against the step surface 30d of the top 30a. When the valve seat 31 is positioned, a gap L4 is formed between the valve seat 31 and the top portion 30a of the cylinder head 30, and the gap L4 is always provided via the hole 30e of the cylindrical portion 30b. It communicates with the reservoir R. On the other hand, in the cylinder portion 30b of the cylinder head 30, the upper opening of the cylinder 1 is screwed to the inner periphery below the step surface 30f, and the outer periphery of the spring seat washer 10 is between the step surface 30f and the cylinder 1. The parts are sandwiched and fixed.

  The valve seat 31 is formed in an annular shape, and the rod body 20 of the rod 2 is inserted inside. The valve seat 31 has a large outer diameter and a screw part 31b that is screwed into the inner periphery of the cylinder part 30b of the cylinder head 30, and an outer diameter that is connected to the lower side of the screw part 31b and is smaller than the outer diameter of the screw part 31b. Leg portion 31c. An annular gap L5 is formed between the leg part 31c and the cylinder part 30b of the cylinder head 30, and the gap L5 is always connected to the extension side chamber L1 via a through hole 10f of a spring seat washer 10 described later. Communicate. Further, the outer peripheral shape of the leg portion 31 c is a hexagonal bolt shape, and a tool can be hooked when the valve seat 31 is screwed into the cylinder head 30.

  The valve seat 31 has an annular groove 31d formed in the upper portion thereof along the circumferential direction, a passage 31a that extends from the annular groove 31d to the outside of the leg portion 31c and continues to the gap L5, and an annular groove 31d. An annular boss portion 31e that surrounds the inner periphery of the annular groove 31d and an annular valve seat 31f that surrounds the outer periphery of the annular groove 31d are formed. When the valve seat 31 is positioned, the collar 33, the spacer 34, and the leaf valve 32 are The inner peripheral portion is sandwiched and fixed between the step surface 30d of the top portion 30a of the cylinder head 30 and the boss portion 31e of the valve seat 31, and the axial force when the valve seat 31 is screwed into the cylinder head 30 is the leaf valve 32. And the axial force can be stabilized.

  The upper and lower inner diameters of the valve seat 31 are partially enlarged, and annular stepped surfaces 31g and 31h are formed at the boundaries between the enlarged portions. In the valve seat 31, the bearing 4 is inserted inside the upper step surface 31 g and is set so that the upper step surface 31 g does not reach the bearing 4 during assembly. The leaf valve 32 can be prevented from being detached from the bearing 4 by inserting the bearing 4 inside the valve seat 31 as in the present embodiment, but if the leaf valve 32 is not detached from the bearing 4, the bearing 4. May not be inserted inside the valve seat 31. Further, when the leaf valve 32 is supported on the inner periphery by a member other than the bearing 4 or when the leaf valve 32 is supported on the outer periphery, the bearing 4 does not need to be inserted inside the valve seat 31. On the other hand, in the valve seat 31, the seal member 5 is lightly press-fitted on the inner side below the lower step surface 31h.

  The leaf valve 32 stacked on the upper side of the valve seat 31 is formed in an annular plate shape and can be elastically deformed, and the bearing 4 is inserted inside. The inner peripheral portion of the leaf valve 32 is sandwiched and fixed between the step surface 30 d of the cylinder head 30 and the boss portion 31 e of the valve seat 31 via the spacer 34 and the collar 33. On the other hand, the outer peripheral portion of the leaf valve 32 can be attached to and detached from the valve seat 31f. The leaf valve 32 bends the outer peripheral side upward from the spacer 34 to open the passage 31a, and the upper and lower gaps L4, L4 By connecting L5, the extension side chamber L1 and the reservoir R can be communicated.

  In the present embodiment, the leaf valve 32 is a relief that opens the passage 31a to allow communication between the extension side chamber L1 and the reservoir R when the pressure in the extension side chamber L1 becomes equal to or greater than a predetermined value during the extension operation of the shock absorber A. It is a valve. In the present embodiment, as described above, since the axial force applied to the leaf valve 32 can be stabilized, variations in cracking pressure of the leaf valve 32 can be suppressed.

  In the present embodiment, the valve seat 31f of the valve seat 31 is provided at a position higher than the boss portion 31e, and the leaf valve 32 is initially bent so that the outer periphery of the leaf valve 32 is above the inner periphery. Although the cracking pressure of the leaf valve 32 is high, the cracking pressure of the leaf valve 32 can be appropriately changed according to the characteristics of the desired damping force. In addition, the configuration of the relief valve that opens and closes the passage 31a can be changed as appropriate, and may include a plurality of leaf valves 32, so that the initial deflection is not applied to the leaf valve 32 that constitutes the relief valve. Also good. Alternatively, the outer peripheral portion of the leaf valve 32 may be fixed by being sandwiched between the cylinder head 30 and the valve seat 31, and the inner peripheral portion of the leaf valve 32 may be bent to open the passage 31a.

  In this embodiment, the seal member 5 that is lightly press-fitted inside the valve seat 31 includes annular U-packings 50 and 51 that are provided in series in the vertical direction and arranged back to back, and are in sliding contact with the outer peripheral surface of the rod body 20. The outer periphery of the rod 2 is sealed to improve the sealing performance in the cylinder 1. The U packings 50 and 51 are each provided with a groove 5a along the circumferential direction at one end in the axial direction, and attaching the U packing 50 upward means that the groove 5a faces upward. Attaching the packing 51 downward means attaching the packing 51 so that the groove 5a faces downward. And arranging the U packings 50 and 51 back to back means arranging the U packings 50 and 51 so that the opposite sides of the groove 5a face each other.

  According to the above configuration, when the pressure in the reservoir R increases, the pressure prevents the upper U-packing 50 from being pressed against the outer peripheral surface of the rod 2 to create a gap between the rod 2 and the U-packing 50. At the same time, when the pressure in the cylinder 1 is increased, it is possible to prevent the lower U-packing 51 from being pressed against the outer peripheral surface of the rod 2 by this pressure and a gap between the rod 2 and the U-packing 51 is generated. .

  The configuration of the seal member 5 is not limited to the above, and can be changed as appropriate. The seal member 5 may include a packing other than the U packing, an O-ring, an oil seal formed by combining metal and rubber, and the like. .

  A spring seat washer 10 provided below the valve seat 31 and fixed between the step surface 30f of the cylinder head 30 and the upper end of the cylinder 1 is a center that allows the rod body 20 of the rod 2 to be inserted. A disc-shaped washer portion 10b having a hole 10a, an annular protruding portion 10c that rises upward from the inner peripheral edge of the washer portion 10b and is inserted inside the valve seat 31, and a lower portion from the inner peripheral edge of the washer portion 10b. An annular spring support portion 10d that extends to the side is provided, and an extension spring 11 that relieves shock at the time of the maximum extension of the shock absorber A is fitted to the outer periphery of the spring support portion 10d.

  The protruding portion 10c is inserted inside the leg portion 31c of the valve seat 31, and the protruding portion 10c and the leg portion 31c are opposed to each other so as to connect the inside of the spring seat washer 10 and the gap L5 to prevent air accumulation. 10e and 31i are formed, and a through hole 10f penetrating in the axial direction is formed in the washer portion 10b. The through-hole 10f always communicates the gap L5 connected to the passage 31a and the extension side chamber L1. When the outer peripheral portion of the leaf valve 32 is bent upward and away from the valve seat 31f, and the leaf valve 32 opens the passage 31a, the liquid in the extension side chamber L1 is notched between the spring seat washer 10 and the rod 2, and the notches 10e, 10e, It moves to the reservoir R through 31i, the through hole 10f, the gap L5, the passage 31a, the gap L4, and the hole 30e.

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

In the extension operation of the shock absorber A in which the inner tube t 2 is retracted from the outer tube t 1 and the rod 2 is retracted from the cylinder 1, the leaf valve 60 of the piston 6 is also a leaf of the head member 3 in the low speed region where the piston speed is low. Since the valve 32 is not opened, the liquid in the expansion side chamber L1 to be reduced moves to the reservoir R through the bypass passage 23. When the piston speed increases and reaches the middle speed region, the leaf valve 60 of the piston 6 opens, and the liquid in the expansion side chamber L1 moves to the pressure side chamber L2 that expands through the expansion side piston passage 6a. When the piston speed further increases and reaches the high speed region, the leaf valve 32 of the head member 3 is also opened, and the liquid in the extension side chamber L1 moves to the reservoir R through the passage 31a of the valve seat 31. .

  During the extension operation of the shock absorber A described above, the leaf valve 80 of the base member 8 is opened, so that an insufficient amount of liquid in the cylinder 1 is supplied from the reservoir R to the pressure side chamber L2 through the extension side base passage 8a. The Thus, when the liquid moves from the intermediate chamber L3 to the pressure side chamber L2, the hydraulic fluid corresponding to this movement flows from the reservoir R into the intermediate chamber L3 through the hole 1a.

  Further, in the present embodiment, the leaf valve 61 is a damping valve and the leaf valve 80 is a check valve. Therefore, the shock absorber A mainly uses the liquid for the bypass passage 23, the extension piston passage 6a, the passage. The extension side damping force resulting from the resistance when passing through 31a is generated. More specifically, the extension side damping force in the low speed region is mainly caused by the resistance when the liquid passes through the bypass passage 23, and the extension side damping force in the medium speed region is mainly the bypass passage 23 and the extension side piston passage. Due to the resistance when the liquid passes through 6a, the extension side damping force in the high speed region is mainly caused by the resistance when the liquid passes through the bypass passage 23, the extension side piston passage 6a and the passage 31a.

  Further, in the present embodiment, since the seal member 5 is provided with the downward U packing 51, even if the expansion side chamber L <b> 1 is pressurized during the extension operation, the liquid in the expansion side chamber L <b> 1 moves around the rod 2 at the U packing 51. It does not leak into the reservoir R through. However, for example, in the shock absorbers of FIGS. 3A and 3B, the seal member 500 is not provided with a downward seal, and is configured only with an upward seal. In such a case, when the pressure in the expansion side chamber L1 is increased, a gap may be formed between the upward seal member 500 and the rod 2 due to the pressure in the expansion side chamber L1, and liquid may leak into the reservoir R from this gap. There is a problem that it is difficult to predict the cracking pressure of the seal member 500 and the flow rate through the gap, and it is difficult to adjust the extension side damping force.

  On the other hand, according to the configuration of the present embodiment, it is possible to eliminate the flow of liquid from the seal member 5 portion toward the reservoir R. Therefore, when adjusting the extension side damping force, only the flow rate of the liquid passing through the leaf valve 60 of the piston 6 and the leaf valve 32 of the head member 3 that is easy to predict is taken into consideration. The flow rate may be controlled by a solenoid valve, and the extension side damping force can be easily adjusted to a desired damping force. Furthermore, it is possible to generate a large extension side damping force from around the piston speed of zero, and it is also possible to lock the extension side chamber L1 by closing the bypass passage 23. You may make it adjust.

  In the above description, the piston speed region is divided into a low speed region, a medium speed region, and a high speed region, but the threshold value of each region can be arbitrarily set.

  On the other hand, when the shock absorber A compresses when the inner tube t2 enters the outer tube t1 and the rod 2 enters the cylinder 1, the liquid in the compression side chamber L2 to be reduced opens the leaf valve 61 of the piston 6, It moves to the expansion side chamber L1 that expands through the piston passage 6b.

  During the compression operation of the shock absorber A, the excess liquid in the cylinder 1 opens the leaf valve 81 of the base member 8, and moves from the pressure side chamber L2 to the intermediate chamber L3 through the pressure side base passage 8b. As described above, when the liquid moves from the pressure side chamber L2 to the intermediate chamber L3, the liquid corresponding to the movement is discharged from the intermediate chamber L3 to the reservoir R through the hole 1a.

  Further, as described above, since the leaf valves 61 and 81 according to the present embodiment are both damping valves, the shock absorber A is used when the liquid passes through the pressure side piston passage 6b and the pressure side base passage 8b. Generates compression side damping force due to resistance. In the present embodiment, the gas and the liquid are in contact with each other through the liquid surface in the reservoir R, and the gas and the liquid are not separated by the partition wall or the like. When the pressure in the reservoir R is increased by being reduced, more gas is dissolved in the liquid. When the shock absorber A starts to extend, a liquid in which many gases are dissolved is sucked into the cylinder 1 through the hole 1a.

And in the part where the flow velocity of the liquid moving in the cylinder 1 is increased due to the expansion and contraction operation of the shock absorber A, the gas dissolved in the liquid is deposited at a low pressure. Since it moves, it gathers in the vicinity of the head member 3 and when the leaf valve 32 of the head member 3 is opened, the gas is preferentially discharged. Therefore, even if the sealing member 5 is provided and the sealing performance in the cylinder 1 is improved, the gas in the cylinder 1 is not discharged, and the damping force generation response is prevented from being lowered, and the performance of the shock absorber A is improved. Can be kept in.

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

  In the present embodiment, the leaf valve 32 of the head member 3 is fixed with the inner peripheral portion being sandwiched between the cylinder head 30 and the valve seat 31, and the initial deflection is given so that the outer periphery is above the inner periphery. It has been.

  According to the above configuration, the cracking pressure of the leaf valve 32 is increased, and when the pressure in the expansion chamber L1 becomes high, the liquid in the expansion chamber L1 can be discharged together with the air deposited in the cylinder 1 to the reservoir R. . Further, when initial deflection is applied to the leaf valve 32, when the leaf valve 302 is merely sandwiched between peripheral parts without receiving an axial force as in the shock absorber shown in FIG. If there is play between the valve 302 and the peripheral parts, the amount of initial deflection of the leaf valve 302 becomes small, and there is a problem that the cracking pressure tends to vary.

  On the other hand, in the present invention, since the axial force can be applied to the leaf valve 32 and the axial force can be stabilized, even when the initial deflection is applied to the leaf valve 32, the deflection amount of the initial deflection is stabilized. The variation in cracking pressure can be suppressed. The cracking pressure of the leaf valve 32 can be changed as appropriate according to the desired damping force characteristics, and the leaf valve 32 need not be initially bent.

  Moreover, in this Embodiment, the sealing member 5 consists of a pair of upper and lower U packings 50 and 51 arrange | positioned back to back.

  According to the above configuration, the upward U-packing 50 can prevent the liquid or gas in the reservoir R from entering the cylinder 1 even if the pressure in the reservoir R increases, By providing the U-packing 51, it is possible to prevent the liquid in the extension side chamber L1 from leaking to the reservoir R even if the pressure in the extension side chamber L1 increases. For this reason, as in the present embodiment, when the expansion side damping force is to be adjusted by the electromagnetic valve, it is not necessary to consider the leakage from the seal member 5 portion, which is difficult to predict. It is possible to easily adjust to the damping force.

  Further, as described above, when the directional seals (U packings 50 and 51 in the present embodiment) are provided upward and downward, the pair of seals and the bearing 4 must be arranged in series vertically. Don't be. For this reason, for example, when a downward seal is further added to the valve seat 300 in FIG. 3A or the guide member 310 in FIG. 3B, there is a problem that the head members 3A and 3B become more bulky in the axial direction. In such head members 3A and 3B, if the axial lengths of the valve seat 300 and the guide member 310 are to be shortened, the bearing 4 is shortened, and the seal member 500 and the bearing 4 are likely to interfere with each other. There is a bug to do.

  On the other hand, in the present invention, the bearing 4 is supported by the cylinder head 30 and the seal member 5 is held by the valve seat 31 so that the member supporting the bearing 4 and the member supporting the seal member 5 are separated. It is possible to suppress the head member 3 from being bulky in the axial direction. For this reason, even when the directional seal is provided upward and downward as in the present embodiment, the length of the bearing 4 can be made sufficiently long while suppressing the head member 3 from being bulky in the axial direction. It becomes possible to easily suppress the interference between the seal member 5 and the bearing 4.

  The configuration of the seal member 5 is not limited to the above. For example, the seal member 5 may be a non-directional seal such as an O-ring, and the buffer shown in FIGS. 3 (a) and 3 (b). It is good also as providing the sealing member 500 which consists only of an upward seal like a container.

  In the present embodiment, the bearing 4 is inserted inside the leaf valve 32 of the head member 3, and the leaf valve 32 is supported by the bearing 4 on the inner periphery.

  According to the above configuration, since the bearing 4 and the leaf valve 32 can be assembled in the axial direction, the head member 3 can be made more compact.

  In the present embodiment, the leaf valve 32 is supported by the bearing 4 on the inner periphery, and the inner periphery is fixed between the cylinder head 30 and the valve seat 31 via the collar 33 and the spacer 34. Has been. According to this configuration, when the cylinder head 30 is made of aluminum and the collar 33 is made of steel, the collar 33 can be reduced in size by reducing the outer diameter of the collar 33. The outer peripheral portion of the valve 32 is fixed by being sandwiched between the cylinder head 30 and the valve seat 31 via a collar and a spacer, and is set so as to open the passage 31a by bending the inner peripheral side upward from the spacer. Also good.

  In addition, as in the present embodiment, the cylinder head 30, the collar 33, and the spacer 34 can be separately provided to improve the degree of freedom of material selection for each member. The spacer 34, the collar 33, and the cylinder head 30 may be integrated.

  Further, in the present embodiment, the shock absorber A includes a cylinder 1 connected to the wheel side and containing a liquid, and a rod 2 connected to the vehicle body side and inserted into the cylinder 1 so as to be movable in the axial direction. A head member 3 that is attached to the upper opening of the cylinder 1 and through which the rod 2 passes, an annular bearing 4 that is supported by the head member 3 and pivotally supports the rod 2, and is held by the head member 3. An annular seal member 5 that seals the outer periphery of the rod 2 and a reservoir R that is formed outside the cylinder 1 and stores liquid.

  The head member 3 includes an annular top portion 30a that holds the bearing 4 on the inner periphery, and a cylindrical tube portion 30b that extends from the top portion 30a toward the cylinder 1 and is formed into a cap shape. And an annular valve seat 31 that is screwed into the inner periphery of the cylindrical portion 30b and holds the sealing member 5 on the inner periphery, and the inside of the cylinder 1 and the reservoir R that are formed in the valve seat 31 communicate with each other. And an annular plate-like leaf valve 32 that opens and closes the passage 31a while sandwiching an inner peripheral portion between the cylinder head 30 and the valve seat 31.

  According to the above configuration, since the axial force applied when the valve seat 31 is screwed into the cylinder head 30 is applied to the inner peripheral portion of the leaf valve 32, the axial force applied to the valve seat 31 is stabilized and functions as a relief valve. Variations in the cracking pressure of the valve 32 can be suppressed.

  Further, even if the axial force applied to the leaf valve 32 is stabilized by twisting, the bearing 4 is supported by the cylinder head 30 and the seal member 5 is supported by the valve seat 31. It is possible to shorten the length X from the upper end of the cylinder head 30 to the lower end of the valve seat 31 that is the end surface facing the inside of the cylinder 1 in the head member 3. Therefore, it is possible to suppress the head member 3 from being bulky in the axial direction and to make the head member 3 compact.

  The above effect can be obtained in the same manner when the outer peripheral portion of the leaf valve 32 is sandwiched between the cylinder head 30 and the valve seat 31 and an axial force by twisting is applied to the outer peripheral portion of the leaf valve 32. be able to.

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

A Shock absorber R Reservoir 1 Cylinder 2 Rod 3 Head member 4 Bearing 5 Seal member 30 Cylinder head 30a Top portion 30b Tube portion 31 Valve seat 31a Passage 32 Leaf valve 50, 51 U packing

Claims (4)

A cylinder that is connected to the wheel side and accommodates liquid, a rod that is connected to the vehicle body side and is inserted in the cylinder so as to be movable in the axial direction, and is attached to the upper opening of the cylinder so that the rod passes therethrough. a head member, an annular bearing is held on the head member for axially supporting the rod, and an annular seal member for sealing the outer periphery of the held the rod in the head member, is formed outside the cylinder liquid And a reservoir for storing
The head member includes a cylinder head which is formed in cap-like and a inner annular top portion for holding the bearing in the circumferential and cylindrical tubular portion extending cylinder side from the top, the inner periphery of the tubular portion an annular valve seat for holding the sealing member on the inner peripheral screwed, the cylinder with a passage formed in the valve seat for communicating the inside the cylinder and the reservoir, the said bearing inside is inserted A shock absorber comprising: an annular plate-like leaf valve that opens and closes the passage while sandwiching an inner peripheral portion or an outer peripheral portion between the head and the valve seat. Upper Symbol leaf valve, shock absorber according to claim 1, characterized in that it is supported inner circumference in the bearing. The shock absorber according to claim 1 or 2, wherein the seal member includes a pair of upper and lower U packings arranged back to back. The leaf valve is fixed with an inner peripheral portion sandwiched between the cylinder head and the valve seat, and is provided with an initial deflection so that an outer periphery is higher than an inner periphery. The shock absorber according to any one of claims 1 to 3.

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