JP2012197859A - Damping valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a damping valve that can exhibit a damping force reducing effect at the contraction operation of a damper, and can improve the riding comfort of a vehicle.SOLUTION: The damping valve V comprises: a piston 2 which is movably inserted into a cylinder and defines an elongation-side chamber R1 and a pressure-side chamber R2 in the cylinder; a damping passage 3; a piston rod 4; a bypass 5 which is arranged at the piston rod 4 and makes the pressure-side chamber R2 communicate with the elongation-side chamber R1 by bypassing the damping passage 3; and a relief valve 6 for opening the bypass 5 by the action of the pressure of the pressure-side chamber R2. The bypass 5 has a valve hole 5a formed at the piston rod 4 and a lateral hole 5b communicating with the valve hole 5a. The relief valve 6 has an annular valve seat 16 arranged in the middle of the valve hole 5a, a valve body 17 which is slidably inserted into the valve hole 5a and defines a back-pressure chamber P in the valve hole 5a; a biasing spring 18 which biases the valve body 17; a throttle 19 which makes the back-pressure chamber P communicate with the elongation-side chamber R1; and an adjusting mechanism 20 which adjusts an initial load of the biasing spring 18.

Description

  The present invention relates to an improved damping valve.

  Conventionally, this type of damping valve is embodied in, for example, a piston part of a shock absorber for a vehicle, and an annular leaf valve is stacked on an outlet end of a port provided in the piston part. Piston valves that open and close ports are known.

  In particular, in the above-described valve structure in which the port is opened and closed by the leaf valve by fixing and supporting the inner periphery of the leaf valve and bending the outer periphery, the damping force in the low speed region of the piston speed is reduced when the leaf valve deflection rigidity is reduced. On the contrary, if the flexural rigidity is increased, the damping force in the medium to high speed region of the piston speed becomes too large, and it is difficult to satisfy the riding comfort in the vehicle in all speed regions.

  In order to solve this problem, the leaf valve is slidably mounted on the outer periphery of a cylindrical piston nut attached to the tip of the piston rod without fixedly supporting the inner peripheral side of the leaf valve. Furthermore, a valve structure for energizing the leaf valve with a coil spring has been proposed.

  In the shock absorber using this valve structure, when the piston speed when the piston is extended, the leaf valve does not open and the damping force is generated only by the orifice stamped on the valve seat. Therefore, the damping characteristic is substantially the same as that of the valve structure in which the inner periphery is fixedly supported.

  On the other hand, in this valve structure, when the piston speed of the shock absorber reaches the medium to high speed region, the pressure of the hydraulic oil passing through the port acts on the leaf valve, the leaf valve is bent and opened, and the biasing force of the coil spring In contrast to this, the leaf valve lifts and retreats from the piston in the axial direction together with the main valve, and the flow passage area becomes larger than the valve structure in which the inner periphery is fixedly supported. Therefore, in the shock absorber to which this valve structure is applied, the damping force in the medium / high speed region of the piston speed does not become excessive, and the riding comfort in the vehicle can be satisfied in all speed regions during the extension operation. (For example, refer to Patent Document 1).

JP-A-9-291196 (FIG. 1)

  In the damping valve disclosed in the above-mentioned Japanese Patent Laid-Open No. 9-291196, the damping force of the shock absorber can be reduced only when the shock absorber is extended. The damping force at the time cannot be reduced, and the damping force reduction effect is not exhibited especially for shocking vibration input that pushes up the wheel generated when the vehicle travels over the unevenness on the road surface.

  Therefore, in a shock absorber equipped with a conventional damping valve, when such vibration is input to the wheel, the thrust vibration cannot be sufficiently reduced and the vibration is transmitted to the vehicle body. There is a problem that an impact called an impact shock is applied to the vehicle and the ride comfort in the vehicle cannot be sufficiently improved.

  In addition, in the conventional damping valve, even if you want to tune the damping characteristics of the shock absorber during the contraction operation according to the user's preference, it is necessary to take out the damping valve from the shock absorber and replace the coil spring for tuning. Tuning work is very troublesome.

  Therefore, the present invention was devised to improve the above-described problems, and the object of the present invention is to exhibit a damping force reducing effect during the contraction operation of the shock absorber. It is an object of the present invention to provide a damping valve that can improve the comfort and can easily tune the damping characteristics when the shock absorber is contracted.

  In order to solve the above-described problems, the problem-solving means of the present invention includes a piston that is movably inserted into a cylinder and divides the cylinder into an extension side chamber and a pressure side chamber, and the piston is provided on the piston. A damping passage communicating the side chamber and the pressure side chamber, a piston rod movably inserted into the cylinder and connected to the piston at one end, and provided on the piston rod to bypass the damping passage In a damping valve including a bypass communicating the compression side chamber with the extension side chamber and a relief valve opening the bypass by the action of the pressure side chamber, the bypass opens from one end of the piston rod facing the pressure side chamber. A valve hole extending in the axial direction of the piston rod and a lateral hole that opens from a side portion of the piston rod facing the extension side chamber and communicates with the valve hole. A half valve is provided in the middle of the valve hole and on the pressure side chamber side with respect to the opening of the horizontal hole, and in the valve hole and slides on the extension side chamber side with respect to the annular valve seat. A valve body that is movably inserted to partition a back pressure chamber in the valve hole; a biasing spring that is inserted into the back pressure chamber and biases the valve body toward the annular valve seat; and the piston A throttle provided on the rod and communicating the back pressure chamber with the extension side chamber and an adjusting mechanism for adjusting the urging force of the urging spring are provided.

  According to the valve structure of the present invention, the damping force can be reduced when the shock absorber is contracted, the ride comfort of the vehicle can be improved, and the damping characteristics when the shock absorber is contracted. Can be easily tuned.

It is a longitudinal cross-sectional view of the shock absorber to which the damping valve in one embodiment was applied. It is a figure which shows the damping characteristic at the time of contraction action | operation of the buffer with which the damping valve in one Embodiment was applied. It is a figure explaining the change of the damping characteristic at the time of the shrinkage | contraction operation | movement of a shock absorber by adjustment of the initial load of a biasing spring.

  The present invention will be described below based on the embodiments shown in the drawings. As shown in FIGS. 1 and 2, the damping valve V in one embodiment is applied to a shock absorber D, and is movably inserted into the cylinder 1 so that the expansion side chamber R1 and the compression side chamber R2 are inserted into the cylinder 1. 1, a damping passage 3 provided in the piston 2 for communicating the expansion side chamber R1 and the pressure side chamber R2, and a piston 2 at the lower end in FIG. Are connected to each other, a bypass 5 provided in the piston rod 4 to bypass the damping passage 3 and connect the pressure side chamber R2 to the expansion side chamber R1, and the bypass 5 is opened by the action of the pressure in the pressure side chamber R2. And a relief valve 6.

  On the other hand, as shown in FIG. 1, the shock absorber D to which the damping valve V is applied is slidably inserted into the cylinder 1, the piston 2, the piston rod 4, and the cylinder 1. A free piston 7 that divides the air chamber G, a rod guide 8 that closes the upper end of the cylinder 1 in FIG. 1 and slidably supports the piston rod 4, and a bottom cap that closes the lower end of the cylinder 1 in FIG. 9 and. The extension side chamber R1 and the pressure side chamber R2 in the cylinder 1 are filled with fluid such as hydraulic oil, and the gas chamber G is filled with gas. In addition to the hydraulic oil, water or an aqueous solution may be used as the fluid. The gas filled in the air chamber G may be an inert gas such as nitrogen that hardly changes the properties of the liquid when the liquid is hydraulic oil.

  Since the shock absorber D is set to a so-called single rod type, the volume of the piston rod 4 that enters and exits the cylinder 1 as the shock absorber D expands and contracts is the volume of the gas in the air chamber G. The free piston 7 expands or contracts and is compensated by moving up and down in FIG. As described above, the shock absorber D is set to be a single cylinder type in the present embodiment, but instead of installing the free piston 7 and the air chamber G, a reservoir is provided on the outer periphery or outside of the cylinder 1 to provide the reservoir. The volume compensation of the piston rod 4 may be performed by Further, the shock absorber D may be set to a double rod type instead of a single rod type. In addition, when the fluid filled in the expansion side chamber R1 and the pressure side chamber R2 is gas, the air chamber G and the reservoir can be omitted.

  Hereinafter, each part will be described in detail. The piston rod 4 has a small-diameter portion 4a formed at the lower end side in FIG. 1 and a screw portion 4b formed at the distal end side of the small-diameter portion 4a.

  The piston 2 is formed in an annular shape, and the small diameter portion 4a of the piston rod 4 is inserted on the inner peripheral side thereof. Further, the piston 2 is provided with a damping passage 3 and an extension side passage 10 that communicate the extension side chamber R1 and the pressure side chamber R2. Further, the piston 2 includes a valve seat 11 that surrounds the outer periphery of the upper end opening of the damping passage 3 at the upper end in FIG. 1, and a valve seat 12 that surrounds the outer periphery of the lower end opening of the extension side passage 10 at the lower end in FIG. I have.

  1 is stacked with a leaf valve 13 that opens and closes the valve seat 11 and opens and closes the upper end opening in FIG. 1 of the damping passage 3. 1 is stacked with a leaf valve 14 that opens and closes the valve seat 12 and opens and closes the lower end opening in FIG.

  The leaf valves 13 and 14 are both formed in an annular shape, and a piston 4 is inserted into a small diameter portion 4 a of the piston rod 4 on the inner peripheral side, stacked on the piston 2, and screwed onto a screw portion 4 b of the piston rod 4. The nut 15 is fixed to the piston rod 4 together with the piston 2 in a state where the outer side deflection is allowed.

  Each of the leaf valves 13 and 14 is configured as a laminated leaf valve in which a plurality of annular plates are stacked. The leaf valves 13 and 14 are provided with notches 13a and 14a on the outer periphery of the annular plate contacting the valve seats 11 and 12, respectively. When the valves 13 and 14 are seated on the valve seats 11 and 12, the notches 13a and 14a function as orifices. Instead of providing the orifices by providing the notches 13a and 14a on the annular plate side, recesses may be imprinted in the valve seats 11 and 12 so that they function as the orifices.

  The leaf valve 13 is bent and opened by the differential pressure between the compression side chamber R2 and the expansion side chamber R1 during the contraction operation of the shock absorber D, opens the damping passage 3, and moves from the compression side chamber R2 to the expansion side chamber R1. In addition, the damping passage 3 is closed when the shock absorber D is extended. Therefore, the damping passage 3 is set as a one-way passage that allows only the flow of fluid from the pressure side chamber R2 toward the extension side chamber R1 by the leaf valve 13. In contrast to the leaf valve 13, the other leaf valve 14 opens the expansion-side passage 10 when the shock absorber D is extended to provide resistance to the fluid passing therethrough, and closes the expansion-side passage 10 during the contraction operation. That is, the leaf valve 14 is a damping force generating element that generates an extension side damping force during the contraction operation of the shock absorber D, and the extension side passage 10 is moved from the extension side chamber R1 to the compression side chamber R2 by the leaf valve 14. It is set as a one-way passage allowing only fluid flow. In addition to the above-described leaf valves 13 and 14, for example, a configuration in which a choke and a leaf valve are arranged in parallel instead of the orifice is adopted as a valve that gives resistance to the fluid passing through the damping passage 3 and the extension side passage 10. In addition to the leaf valve, a poppet valve and other configurations can also be employed.

  The bypass 5 opens from the lower end in FIG. 1 as one end of the piston rod 4 facing the compression side chamber R2 and extends in the axial direction of the piston rod 4, and opens from the side of the piston rod 4 facing the expansion side chamber R1. And a lateral hole 5b communicating with the valve hole 5a.

  The relief valve 6 is provided in the middle of the valve hole 5a and on the pressure side chamber side of the opening of the lateral hole 5b. The relief valve 6 is provided on the lower side in FIG. 1, and the annular valve seat 16 in the valve hole 5a. A valve body 17 that is slidably inserted upward in FIG. 1, which is closer to the extension side chamber R <b> 1, and partitions the back pressure chamber P in the valve hole 5 a, and a valve body 17 that is inserted into the back pressure chamber P. For adjusting the urging force of the urging spring 18, a throttle 19 provided on the piston rod 4 for communicating the back pressure chamber P to the expansion side chamber R 1, and an adjustment for adjusting the urging force of the urging spring 18. And a mechanism 20.

  The annular valve seat 16 is annular and is press-fitted into the valve hole 5a and fixed. The annular valve seat 16 is a separate component from the piston rod 4, but a step portion may be provided on the inner periphery of the valve hole 5a of the piston rod 4 to form the annular valve seat. In this case, the valve body 17 and the urging spring 18 may be inserted from the hollow portion 4c side leading to the valve hole 5a from the upper end of the piston rod 4 in FIG. The annular valve seat 16 may be fixed by a method other than press fitting.

  The valve body 17 is mounted along the circumferential direction on the outer periphery of the body portion 17a, the body portion 17a that is in sliding contact with the inner periphery of the valve hole 5a, the conical valve head 17b provided at the lower end of the body portion 17a in FIG. The two seal rings 17c are provided. Since the valve head 17b has a conical shape, it can abut against the inner periphery of the upper end of the annular valve seat 16 in FIG. 1 without any gap, and the communication between the compression side chamber R2 and the extension side chamber R1 through the bypass 5 is blocked. can do.

  As described above, in the seated state where the valve body 17 is in contact with the annular valve seat 16, the relief valve 6 is closed to shut off the bypass 5, and in the state where the valve body 17 is separated from the annular valve seat 16, the relief valve 6 is closed. The valve 6 is opened to open the bypass 5.

  Further, when the valve body 17 moves upward in FIG. 1 from the closed position where the valve head 17b contacts the annular valve seat 16 and moves away from the annular valve seat 16, the valve head 17b and the annular valve seat 16 are opened. An annular gap is formed between the inner peripheral edge and the compression side chamber R2 and the extension side chamber R1. However, the valve head 17b that is attached to and detached from the annular valve seat 16 has a conical shape. The annular gap can be gradually increased by increasing the amount of displacement of the valve body 17 upward, that is, the flow passage area can be gradually increased.

  Further, by providing two seal rings 17c on the valve body 17, the space between the valve body 17 and the piston rod 4 is tightly sealed so that the front side and the back side of the valve body 17 which are the lower side in FIG. The pressure chamber P can be reliably prevented from communicating with the outer periphery of the valve body 17 and the valve body can be moved when the valve body 17 moves in the vertical direction in FIG. 17 can be prevented, the valve head 17b can be brought into contact with the annular valve seat 16 without deviation, and the valve can be reliably closed. You can show your power.

  In addition, a small-diameter convex portion 17d is provided on the rear side end, which is the upper end in FIG. 1 of the trunk portion 17a, and the convex portion 17d is fitted to the inner periphery of the coiled biasing spring 18. . The urging spring 18 is interposed between the spring receiver 21 and the valve body 17 in the adjusting mechanism 20 in a compressed state, and urges the valve body 17 toward the annular valve seat 16. Even when seated on the annular valve seat 16, the urging force is exerted and an initial load is applied to the valve body 17.

  The restrictor 19 provides resistance to the flow of fluid that exchanges between the back pressure chamber P and the extension side chamber R1. Therefore, when the relief valve 6 is opened and the valve body 17 moves backward in a direction away from the annular valve seat 16, the throttle 19 is opened when the fluid is pushed out from the compressed back pressure chamber P to the expansion side chamber R1. Since the pressure in the back pressure chamber P is increased, the pressure in the back pressure chamber P is restrained from retreating the valve element 17. On the contrary, when the valve body 17 moves forward in the direction of approaching from the annular valve seat 16, when the fluid is sucked into the expansion-side chamber R <b> 1 into the back-pressure chamber P to be expanded, the throttle 19 has a pressure in the back-pressure chamber P. Is reduced, the forward movement of the valve body 17 is suppressed.

  The adjustment mechanism 20 includes a spring receiver 21 that supports one end of the urging spring 18, an adjuster 22 that is rotatably attached to the other end of the piston rod 4, and a spring receiver 21 that is mounted in the back pressure chamber P by the rotation of the adjuster 22. A feed screw mechanism 23 for moving the piston rod 4 back and forth is provided.

  The adjuster 22 is rotatably mounted at the upper end in FIG. 1 which is the other end of the piston rod 4, and is provided at a dial 22a operable from the outside of the piston rod 4 and at the lower portion of the dial 22a in FIG. And a shaft 22b inserted into the hollow portion 4c communicating with the valve hole 5a from the other end of the piston rod 4. The feed screw mechanism 23 includes a screw portion 4d provided on the inner periphery of the hollow portion 4c of the piston rod 4, a bottomed cylindrical nut 24 whose outer periphery is screwed to the screw portion 4d, and one end. 1 includes a connecting rod 25 whose lower end is connected to the spring receiver 21 and whose other end contacts the bottom of the nut 24.

  The inner peripheral cross-sectional shape of the nut 24 and the outer peripheral cross-sectional shape of the shaft 22b are the same shape other than a perfect circle, and when the shaft 22b of the adjuster 22 is fitted in the nut 24, the nut 24 and the adjuster 22 are in the circumferential direction. However, relative movement in the axial direction is allowed, although relative rotation is impossible.

  Therefore, when the dial 22a of the adjuster 22 is rotated, the nut 24 also rotates in the circumferential direction within the hollow portion 4c of the piston rod 4, but since the nut 24 is screwed to the screw portion 4d, the nut 24 The rod 4 is moved in the vertical direction in FIG.

  Further, the connecting rod 25 receives the urging force of the urging spring 18 through the spring receiver 21, is urged upward in FIG. 1, and is pressed against the bottom of the nut 24.

  In the adjusting mechanism 20 configured as described above, when the dial 22a of the adjuster 22 is rotated, the nut 24 moves in the vertical direction in FIG. 1 with respect to the piston rod 4, but the connecting rod 25 is a biasing spring. Since the nut 24 is always pressed against the nut 24 by the vertical movement of the nut 24, the spring receiver 21 is also synchronized with the nut 24 via the connecting rod 25 in the back pressure chamber P with respect to the piston rod 4. It moves up and down in FIG. That is, the adjusting mechanism 20 can displace the spring receiver 21 in the vertical direction in FIG. 1 with respect to the piston rod 4 in the manner of a feed screw, and the compression degree of the biasing spring 18 is changed by the displacement of the spring receiver 21. The initial load applied to the valve body 17 can be changed. The operation of the dial 22a of the adjuster 22 may be performed manually by the user, or may be rotated by an actuator. When rotating by the actuator, the actuator is operated according to the vehicle body posture. You may make it provide the control apparatus which controls.

  The relief valve 6 is configured as described above, and the force that presses the valve element 17 in the direction away from the annular valve seat 16 by the action of the pressure in the pressure side chamber R2 urges the valve element 17 toward the annular valve seat 16 side. When the valve body 17 is retracted against the urging force of the urging spring 18 and the force by which the back pressure chamber P presses the valve body 17 toward the annular valve seat 16 with internal pressure, the valve 5 opens and the bypass 5 is opened. To do. That is, the relief valve 6 is opened when the pressure in the pressure side chamber R2 reaches a predetermined valve opening pressure, and the bypass 5 is opened. The adjustment spring 20 causes the biasing spring 18 to move to the valve body 17 by the adjusting mechanism 20. It can be adjusted by changing the initial load applied.

  Further, since the back pressure chamber P functions to suppress the movement of the valve body 17, even if the pressure in the pressure side chamber R2 fluctuates in vibration, the vibration of the valve body 17 can be suppressed, and the relief valve 6 The valve opening degree does not change in vibration, and the damping force can be exhibited stably.

  The damping valve V is configured as described above, and the operation of the damping valve V will be described below. The damping valve V exerts a damping force on the shock absorber D when the shock absorber D is contracted.

  When the piston speed is in the low speed region during the contraction operation of the shock absorber D, the compression side chamber R2 is compressed and the expansion side chamber R1 is expanded by the piston 2, but the leaf valve 13 is also relief when the piston speed is low. Since the valve 6 is not opened, the fluid in the pressure side chamber R2 passes through only the notch 13a functioning as an orifice provided on the outer periphery of the leaf valve 13, and is moved to the extension side chamber R1. Therefore, the damping characteristic (damping force characteristic with respect to the piston speed) of the shock absorber D at this time is an orifice that rises so that the compression side damping force is proportional to the square of the piston speed with respect to the piston speed, as shown in FIG. It has a characteristic square characteristic, and in this low speed region, the attenuation coefficient is relatively large (section a in FIG. 2). The attenuation coefficient is grasped as the slope of the attenuation characteristic in FIG.

  Further, when the medium speed exceeds the low speed, the fluid bends the outer periphery of the leaf valve 13, passes through the gap between the leaf valve 13 and the valve seat 11, and moves from the compression side chamber R2 to the extension side chamber R1. Then, until the area of the gap between the leaf valve 13 and the valve seat 11 becomes equal to the flow passage area of the attenuation passage 3, the damping characteristic of the shock absorber D is governed by the characteristic of the leaf valve 13 (in FIG. 2). b section). When the area of the gap between the leaf valve 13 and the valve seat 11 becomes larger than the flow passage area of the attenuation passage 3, the attenuation characteristic of the shock absorber D is governed by the characteristic of the attenuation passage 3 (section c in FIG. 2). . That is, in the section “b”, the area of the gap between the leaf valve 13 and the valve seat 11 is smaller than the flow path area of the attenuation passage 3. The area of the gap between the valve seat 11 and the flow of fluid between the leaf valve 13 and the valve seat 11 is restricted, so that the damping characteristic of the shock absorber D is the characteristic of restricting the flow of fluid at the leaf valve 13, that is, The characteristic of generating a damping force proportional to the pressure increase in the pressure chamber R2 becomes dominant. On the other hand, in the section c, the piston speed is increased and the pressure in the pressure side chamber R2 is increased, so that the amount of deflection of the leaf valve 13 is increased, but the area of the gap between the leaf valve 13 and the valve seat 11 is attenuated. Since the flow passage area is larger than the flow passage area of the passage 3, the flow passage area is the smallest because it becomes the flow passage area of the attenuation passage 3 and the flow of fluid is restricted by the attenuation passage 3. The attenuation characteristic is dominated by the port characteristic that restricts the flow of fluid in the attenuation passage 3. The reason why the damping coefficient in the b section is larger than the damping coefficient in the c section is that a restoring force is applied to the leaf valve 13 to close the damping passage 3 according to the amount of deflection in the b section.

  Next, the case where the piston speed reaches the high speed region, the pressure in the pressure side chamber R2 exceeds the valve opening pressure of the relief valve 6, and the relief valve 6 opens will be described. In this case, not only the leaf valve 13 but also the relief valve 6 is opened, and the pressure side chamber R2 and the extension side chamber R1 are communicated not only by the attenuation passage 3 but also by the bypass 5, and the flow path area is increased. As a result, the pressure in the compression side chamber R2 escapes to the expansion side chamber R1 even through the bypass 5, and the pressure increase in the compression side chamber R2 is suppressed against the increase in the piston speed. As a result, the damping characteristic of the shock absorber D when the piston speed is in the high speed region is proportional to the increase in the piston speed as shown in FIG. The slope of the characteristic becomes small (d section).

  Thus, in the shock absorber D to which the damping valve V of the present invention is applied, the notch 13a functioning as an orifice, the leaf valve 13 and the damping passage 3 are sufficient when the piston speed is in the low / medium speed region during the contraction operation. On the other hand, when the piston speed is in the high speed region, the pressure increase in the compression side chamber R2 is suppressed, and the compression side damping force of the shock absorber D does not become excessive. Therefore, according to the damping valve V of the present invention, the ride comfort in the vehicle can be satisfied in all speed ranges. In the damping valve V according to the present invention, for example, even if the shocking vibration that pushes up the wheel by inputting the bump on the road surface while the vehicle is running, the compression side damping force of the shock absorber D is excessive. Therefore, since the transmission of the shock vibration to the vehicle body is insulated, the impact shock can be effectively reduced.

  Further, in the damping valve V of the present invention, the bypass 5 opens from one end of the piston rod 4 and extends in the axial direction of the piston rod 4 and opens from the side of the piston rod 4 to communicate with the valve hole 5a. The relief valve 6 is composed of a lateral hole 5b, and the relief valve 6 is inserted into the back pressure chamber P, an annular valve seat 16 provided in the valve hole 5a, a valve body 17 slidably inserted into the valve hole 5a, and Since the biasing spring 18 and the throttle 19 provided in the piston rod 4 and communicating the back pressure chamber P to the expansion side chamber R1, both the bypass 5 and the relief valve 6 are provided in the piston rod 4. These do not affect the stroke length of the shock absorber D. Therefore, according to the damping valve V of the present invention, there is no inconvenience of shortening the stroke length of the shock absorber D. Therefore, the shock absorber D can be mounted on a vehicle having a limited mounting space.

  Further, the damping valve V of the present invention includes the adjusting mechanism 20 that adjusts the urging force of the urging spring 18 that urges the valve body 17, so that the initial force that the urging spring 18 applies to the valve body 17. The valve opening pressure of the relief valve 6 can be changed by changing the load. As a result, the piston speed at which the relief valve 6 opens can be changed. Specifically, as the initial load applied to the valve element 17 by the urging spring 18 increases, the valve opening pressure of the relief valve 6 increases. Therefore, when the initial load increases, the piston that opens the relief valve 6 opens. Increases speed. Therefore, the damping characteristic of the shock absorber D increases the piston speed when the relief valve 6 is opened, as shown in FIG. FIG. 3 shows the damping characteristics of the shock absorber D when the initial load is increased in the order of e, f, g, and h. Can understand.

  As described above, in the damping valve V of the present invention, the initial load of the biasing spring 18 can be easily adjusted from the outside, so that the damping characteristics can be easily tuned and the damping characteristics desired by the user can be easily realized. .

  Therefore, according to the damping valve V of the present invention, the damping force can be reduced when the shock absorber is contracted, the riding comfort of the vehicle can be improved, and the shock absorber is retracted. It is possible to easily tune the attenuation characteristics.

  In addition, the valve body 17 of the relief valve 6 includes the conical valve head 17b as described above. However, the present invention is not limited to this. The valve head may be inserted into the valve body, and the bypass 5 may be opened through the valve body by retreating from the annular valve seat 16. Although it is possible to employ a valve that maximizes the flow path area when the relief valve 6 is opened, the flow path area gradually increases in accordance with the distance from the annular valve seat 16 of the valve element 17. By adopting an increasing valve body, it is possible to prevent an extreme inflection point from being generated in the damping characteristic, and to improve the riding comfort in the vehicle.

  In the present embodiment, in order to explain the change of the damping characteristic, the piston speed is provided with sections of low speed, medium speed, and high speed, but the speed of the boundary between these sections is arbitrarily set. The valve opening pressure of the relief valve 6 may be set according to the setting of this section. In other words, when shifting the medium speed and high speed sections to a higher piston speed, the valve opening pressure of the relief valve 6 may be increased. When shifting to a lower speed, the valve opening pressure of the relief valve 6 may be increased. Should be lowered accordingly. Further, when shifting the low speed and medium speed categories to a higher piston speed, the valve opening pressure of the leaf valve 13 may be increased, and when shifting to a lower speed, the valve opening pressure of the leaf valve 13 may be increased. Should be lowered accordingly.

  This is the end of the description of the embodiment of the present invention, but the scope of the present invention is of course not limited to the details shown or described.

DESCRIPTION OF SYMBOLS 1 Cylinder 2 Piston 3 Damping passage 4 Piston rod 5 Bypass 5a Valve hole 5b Side hole 6 Relief valve 16 Annular valve seat 17 Valve body 17c Seal ring 17b Valve head 18 Energizing spring 19 Diaphragm 20 Adjustment mechanism 21 Spring receiver 22 Adjuster

Claims (2)

A piston that is movably inserted into the cylinder and divides the cylinder into an extension side chamber and a pressure side chamber; a damping passage that is provided in the piston and communicates the extension side chamber and the pressure side chamber; and A piston rod that is movably inserted and connected to the piston at one end; a bypass that is provided in the piston rod and bypasses the damping passage and communicates the pressure side chamber to the extension side chamber; and a pressure in the pressure side chamber In the damping valve having a relief valve that opens the bypass by the action of
The bypass opens from one end of the piston rod facing the pressure side chamber and extends in the axial direction of the piston rod, and the horizontal hole opens from the side of the piston rod facing the extension side chamber and communicates with the valve hole And
The relief valve includes an annular valve seat provided in the middle of the valve hole and closer to the pressure side chamber than the opening of the lateral hole, and a slide in the valve hole to the extension side chamber side from the annular valve seat. A valve body that is movably inserted to partition a back pressure chamber in the valve hole; a biasing spring that is inserted into the back pressure chamber and biases the valve body toward the annular valve seat; and the piston A damping valve comprising: a throttle provided on a rod for communicating the back pressure chamber to the extension side chamber; and an adjusting mechanism for adjusting an initial load applied to a valve body of a biasing spring. The adjusting mechanism includes a spring receiver that supports one end of the biasing spring, an adjuster that is rotatably attached to the other end of the piston rod, and the spring receiver that is attached to the piston rod in the back pressure chamber by the rotation of the adjuster. The damping valve according to claim 1, further comprising a feed screw mechanism that moves forward and backward.

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