JP4918022B2 - Damping force adjustment structure of hydraulic shock absorber - Google Patents

Description

  The present invention relates to a damping force adjusting structure for a hydraulic shock absorber.

There exists a thing of patent document 1 as a damping-force adjustment structure of a hydraulic shock absorber. This hydraulic shock absorber stores oil in a cylinder oil chamber, and a piston provided at an insertion end of a piston rod inserted in the cylinder is slidably fitted into the cylinder, and is pressurized by sliding of the piston. The flow of oil from one oil chamber to the other oil chamber is controlled by a damping valve to generate a damping force. And the damping force which a damping valve generate | occur | produces is adjusted by providing the bypass path which bypasses a damping valve, and the free piston which opens and closes this bypass path. The free piston has an orifice that stops the bypass path when the piston speed of the hydraulic shock absorber is low, generates the damping force of the damping valve, and opens the bypass path when the piston speed of the hydraulic shock absorber is high. Move to lower the damping force of the damping valve.
JP2000-110881

  The damping force adjusting structure for a hydraulic shock absorber described in Patent Document 1 controls the damping force characteristic depending on the piston moving speed of the hydraulic shock absorber. Therefore, for example, when the piston movement speed increases during the compression stroke of the hydraulic shock absorber, the free piston moves to a position where the bypass passage is opened and the damping force is reduced, and then reverses to the extension stroke, the piston movement speed is low and the free movement occurs. The piston does not move from the position where the bypass passage is opened, and a high damping force cannot be generated.

  An object of the present invention is to extremely reduce the damping force of the damping valve from the high damping force state at the time of high pressure at which the piston moving speed reaches a constant speed in the damping force adjusting structure of the hydraulic shock absorber.

  According to the first aspect of the present invention, an oil liquid is accommodated in an oil chamber of a cylinder, a piston provided at an insertion end of a piston rod inserted into the cylinder is slidably fitted into the cylinder, and is pressurized by sliding of the piston. In the damping force adjustment structure of a hydraulic shock absorber that generates damping force by controlling the flow of oil from one oil chamber to the other oil chamber by a damping valve, the both oil chambers are bypassed by bypassing the damping valve. A first blow valve and a second blow valve for blowing the pressurized oil in one oil chamber to the other oil chamber are arranged in series in the bypass path to be communicated, and the first blow valve and the second blow valve are arranged in series. The first blow valve and the second blow valve are urged to their closed positions by a single spring that supports the second blow valve on the back surface, and the closed positions of the second blow valves are closed. The first bro at The pressure receiving area of the valve as well as smaller than the pressure receiving area of the second blow valve, in which so as to regulate the opening limit of the first blow valve.

  According to a second aspect of the present invention, in the first aspect of the present invention, a check valve that allows only a flow from the bypass passage to the oil chamber is provided downstream of the second blow valve in the bypass passage.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the first blow valve and the second blow valve blow when the hydraulic shock absorber is compressed.

  According to a fourth aspect of the invention, in the first or second aspect of the invention, the first blow valve and the second blow valve are configured to blow when the hydraulic shock absorber is extended.

  According to a fifth aspect of the present invention, in the first to fourth aspects of the present invention, the first blow valve and the second blow valve are partitioned by a piston that bypasses the damping valve and is provided on the piston rod. It is provided in a bypass passage that connects the rod-side oil chamber and the piston-side oil chamber.

  According to a sixth aspect of the present invention, in the first to fourth aspects of the present invention, the first blow valve and the second blow valve further bypass the damping valve and are provided by a bottom piece provided at the lower end of the cylinder. It is provided in a bypass path that connects the partitioned piston-side oil chamber and the reservoir chamber.

(Claim 1)
(a) When the piston moving speed reaches a constant speed due to the movement of the piston, and the pressure of one oil chamber acting on the bypass passage becomes the opening pressure of the first blow valve, the first blow valve becomes the second blow valve. The spring is compressed through the valve and opened, and the high-pressure oil in one oil chamber is blown into the intermediate pressure chamber between the second blow valve and the damping force of the damping valve is lowered from the high damping force state. . After the first blow valve reaches the opening limit, the second blow valve whose valve opening pressure is lower than that of the first blow valve further compresses the spring, and immediately opens away from the first blow valve. The high pressure oil in one oil chamber and the intermediate pressure chamber is blown to the other oil chamber, and the damping force of the damping valve is extremely lowered.

  (b) After the opening of the second blow valve described above in (a), the pressure in one oil chamber and the intermediate pressure chamber is blown and lowered, and the second blow valve is moved to the first by the biasing force of the spring. When the piston continues to move, the pressure in one oil chamber continues to act on the intermediate pressure chamber from the bypass passage unless the first blow valve is closed again. Then, the second blow valve having a large pressure receiving area is opened again. Therefore, as a result of the second blow valve repeatedly opening and closing, the high pressure oil in one oil chamber and the intermediate pressure chamber is blown to the other oil chamber, and the damping force of the damping valve is continuously lowered.

  (c) When a vehicle climbs over a curb or the like (step) when entering a parking lot from a road, for example, in a general hydraulic shock absorber, the compression side damping force rises rapidly during a sudden compression stroke, making it difficult to operate. In the hydraulic shock absorber according to the present invention, when the oil liquid in one oil chamber becomes a high pressure during an abrupt compression stroke, the first blow valve and the second blow valve operate as described in (a) and (b) above. The damping force of the damping valve is reduced, and the bumps can be overcome lightly and absorb shocks to improve riding comfort.

  (d) Since the damping force characteristic is controlled depending on the pressure in one oil chamber, for example, the pressure in one oil chamber is increased during the compression stroke of the hydraulic shock absorber, and the first and second pressure sides are increased. When the blow valve is opened and the damping force of the compression side damping valve is extremely lowered from the high damping force state and then reversed to the extension stroke, the compression side first and second blow valves are irrelevant, and the extension side damping valve is Normal damping force is generated.

(Claim 2)
(e) A check valve is provided on the downstream side of the second blow valve, and when the moving direction of the piston is reversed, the closing speed of the second blow valve is delayed.

  Therefore, for example, when the unevenness (step) on the road surface on which the vehicle travels is repeated, the first blow valve and the second blow valve are sequentially opened in the compression stroke at the time of passing the first step, and the above (a) to (a) Realize (c). In the compression stroke when the step passes after the second time, the closing speed of the second blow valve is delayed due to the presence of the check valve, and the second blow valve is not closed yet. As a result, the first blow valve is opened. It is in a valve state. Accordingly, in the compression stroke at the time of passing the step after the second time, the oil in one oil chamber is smoothly blown into the other oil chamber, and the damping force of the damping valve is kept low without increasing, Riding over the steps lightly without any lumps can absorb the impact and improve riding comfort.

(Claim 3)
(f) By providing the first and second blow valves on the pressure side, the damping force of the damping valve can be extremely reduced when the hydraulic shock absorber is compressed.

(Claim 4)
(g) By providing the first and second blow valves on the extension side, the damping force of the damping valve can be extremely reduced when the hydraulic shock absorber is extended.

(Claim 5)
(h) The first blow valve and the second blow valve are provided in a bypass passage that bypasses the damping valve and connects the rod-side oil chamber and the piston-side oil chamber defined by the piston provided in the piston rod. Thus, the above-described (a) to (g) can be realized by the piston valve device.

(Claim 6)
(i) The first blow valve and the second blow valve are provided in a bypass path that bypasses the damping valve and connects the piston-side oil chamber and the reservoir chamber defined by the bottom piece provided at the lower end of the cylinder. Thus, the above-described (a) to (g) can be realized by the bottom valve device.

  1 is a schematic cross-sectional view showing a hydraulic shock absorber according to a first embodiment, FIG. 2 is a cross-sectional view showing a compression-side damping force adjusting structure, FIG. 3 is a cross-sectional view showing the operation of the compression-side damping force adjusting structure, and FIG. FIG. 5 is a diagram showing a damping force adjustment result, FIG. 6 is a cross-sectional view showing a compression side damping force adjustment structure of Example 2, and FIG. 7 shows an operation of the compression side damping force adjustment structure. Sectional drawing and FIG. 8 are diagrams showing the damping force adjustment result.

Example 1 (FIGS. 1 to 5)
As shown in FIG. 1, the damping force adjusting hydraulic shock absorber 10 is a double cylinder type composed of a double pipe in which a cylinder 12 is built in a damper tube 11, and a piston rod 13 is inserted into a cylinder 12 containing oil. The axle tube side mounting portion is provided at the lower portion of the damper tube 11 and the vehicle body side mounting portion 14 is provided at the upper portion of the piston rod 13 to constitute a vehicle suspension device.

  The hydraulic shock absorber 10 has a suspension spring 16 interposed between a lower spring seat 15 on the outer periphery of the damper tube 11 and an upper spring seat (not shown) provided on the vehicle body side mounting portion 14 at the upper end portion of the piston rod 13. To do.

  The hydraulic shock absorber 10 clamps a rod guide 17, a bush 18, and an oil seal 19 for the piston rod 13 inserted into the cylinder 12 between the upper end crimped portion 11 </ b> A of the damper tube 11 and the upper end portion of the cylinder 12. It is fixed.

  The damping force adjusting hydraulic shock absorber 10 includes a piston valve device 20 and a bottom valve device 40. The piston valve device 20 and the bottom valve device 40 generate a damping force by controlling the flow of oil and liquid caused by the piston 24 (described later) provided at the insertion end of the piston rod 13 into the cylinder 12 sliding on the cylinder 12. The expansion and contraction vibration of the piston rod 13 accompanying the absorption of the impact force by the suspension spring 16 is suppressed by the damping force generated by them.

(Piston valve device 20)
As shown in FIG. 2, the piston valve device 20 has a screw portion 21 at an insertion end of the piston rod 13 into the cylinder 12, and the screw portion 21 has a washer 22 and upper valve housings for blow valves 70 and 80 described later. 51 is fixed with a nut 23, and the piston 24 is fixed with a nut 25 to a piston mounting portion 52 </ b> A provided in a lower valve housing 52 screwed to the upper valve housing 51.

  The piston 24 is slidably inserted into the cylinder 12, and is provided with an expansion side flow path 31 and a pressure side flow path 32, and an annular central portion of a disk valve-shaped expansion side damping valve 33 is interposed between the piston 24 and the nut 25. The annular central portion of the disc-valve compression side damping valve 34 is clamped between the piston 24 and the stepped surface provided with the piston mounting portion 52A of the lower valve housing 52. That is, the piston valve device 20 divides the inside of the cylinder 12 into a rod-side oil chamber 12A and a piston-side oil chamber 12B by a piston 24, and the rod-side oil chamber 12A and the piston-side oil chamber 12B are provided on the piston 24. The expansion side damping valve 33 that opens and closes the passage 31 and the extension side flow path 31 and the pressure side flow path 32 and the pressure side attenuation valve 34 that opens and closes the pressure side flow path 32 communicate with each other.

  Therefore, at the time of extension, the oil in the rod side oil chamber 12A passes through the extension side flow path 31 of the piston 24, bends and opens the extension side damping valve 33, is guided to the piston side oil chamber 12B, and the extension side damping force Is generated. Further, at the time of compression, the oil in the piston side oil chamber 12B passes through the pressure side flow path 32 of the piston 24, bends and deforms the pressure side damping valve 34, and is guided to the rod side oil chamber 12A to generate a pressure side damping force. .

(Bottom valve device 40)
In the hydraulic shock absorber 10, a gap between the damper tube 11 and the cylinder 12 is defined as a reservoir chamber 12C, and the interior of the reservoir chamber 12C is partitioned into an oil chamber and a gas chamber. In the bottom valve device 40, the bottom piece 41 that partitions the piston-side oil chamber 12 </ b> B and the reservoir chamber 12 </ b> C inside the cylinder 12 is disposed between the lower end portion of the cylinder 12 and the bottom portion of the damper tube 11. The space between the bottom of the bottom piece 41 and the bottom piece 41 can be communicated with the reservoir chamber 12 </ b> C by a flow path provided in the bottom piece 41.

  The bottom valve device 40 includes a disk valve 42 and a check valve 43 as bottom valves for opening and closing a pressure side channel 41A and an extension side channel (not shown) provided in the bottom piece 41, respectively.

  At the time of extension, the oil corresponding to the retraction volume of the piston rod 13 that retreats from the cylinder 12 pushes the check valve 43 open, and the piston side oil chamber passes from the reservoir chamber 12C via the expansion side flow path (not shown) of the bottom piece 41. Replenished to 12B. During compression, the oil corresponding to the volume of the piston rod 13 entering the cylinder 12 opens from the piston-side oil chamber 12B through the pressure-side flow path 41A of the bottom piece 41 by flexing and deforming the disk valve 42 to the reservoir chamber 12C. Extruded to obtain compression side damping force.

  In the hydraulic shock absorber 10, the piston rod 13 is disposed around the piston rod 13 positioned in the rod-side oil chamber 12 </ b> A of the cylinder 12 and on the rebound seat 46 fixed to the piston 24 side (lower side). Is provided with a rebound rubber 47 that is compressed and deformed when the hydraulic shock absorber 10 is fully extended (the maximum extension state of the hydraulic shock absorber 10).

  However, the hydraulic shock absorber 10 is provided with the compression side damping force adjusting device 50 for adjusting the damping force of the piston valve device 20, in this embodiment, the compression side damping force as follows. In the piston valve device 20 described above, the extension side damping force TF generated by the extension side damping valve 33 and the compression side damping force CF generated by the compression side damping valve 34 are shown in FIG. 4 with respect to the piston moving speed V / P. As shown, it changes to a straight line generally indicated by a solid line. The compression-side damping force adjusting device 50 extremely reduces the compression-side damping force CF generated by the compression-side damping valve 34 when the piston moving speed V / P reaches a constant speed, as indicated by a one-dot chain line in FIG. Is.

  As shown in FIG. 2, the compression-side damping force adjusting device 50 bypasses the compression-side damping valve 34 to upper and lower valve housings 51, 52 provided on the screw portion 21 of the piston rod 13 along the central axis of the piston rod 13. A bypass passage 60 that connects the rod-side oil chamber 12A and the piston-side oil chamber 12B is provided. The pressure side first and second blow valves 70, 80 for blowing the fluid in the piston side oil chamber 12 </ b> B pressurized during compression of the hydraulic shock absorber 10 to the rod side oil chamber 12 </ b> A are serially connected in series to the bypass path 60. Arrange and provide.

  The blow valve 70 is composed of a cup-shaped body 70A, and is slidable up and down on the inner periphery of the lower valve housing 52 via a seal member 71 provided on the outer periphery of the cup-shaped body 70A. The bottom of 70A contacts and closes the opening edge of the small-diameter passage 61 that always communicates with the piston-side oil chamber 12B of the bypass passage 60, and the upper end of the cup-shaped body 70A is closed to the lower end of the upper valve housing 51 at the opening end of the rising end. The opening limit is restricted by abutting against the stopper 51A. When the first blow valve 70 is opened from the closed position, the intermediate pressure chamber in which the small-diameter passage 61 (piston-side oil chamber 12B) is partitioned between the inner recess 70B of the cup-shaped body 70A and the second blow valve 80. A valve hole 70 </ b> C communicating with 62 is provided on the outer diameter side from the portion corresponding to the small diameter passage 61 at the bottom of the cup-shaped body 70 </ b> A.

  The second blow valve 80 includes a cup-shaped body 80A, and is slidable up and down on the inner periphery of the upper valve housing 51 via a seal member 81 provided on the outer periphery of the cup-shaped body 80A. At the position, the bottom of the cup-shaped body 80A contacts and closes the opening edge of the inner concave portion 70B of the cup-shaped body 70A of the first blow valve 70 in a stacked manner, and closes the inner concave portion of the cup-shaped body 80A at the opening end of the rising end The compression coil spring 90 interposed between the bottom surface of 80B and the lower end surface of the piston rod 13 is compressed most. When the second blow valve 80 is opened from the closed position, the second blow valve 80 has a valve hole 80C that communicates the intermediate pressure chamber 62 with the inner recess 80B of the cup-shaped body 80A, and a first blow valve at the bottom of the cup-shaped body 80A. 70 on the outer diameter side of the portion corresponding to the opening edge of the inner recess 70B of the cup-shaped body 70A. The upper valve housing 51 includes a communication passage 63 that always communicates the inner recess 80B of the cup-shaped body 80A of the second blow valve 80 with the rod-side oil chamber 12A.

  Accordingly, the compression-side damping force adjusting device 50 includes a first blow valve 70 and a second blow valve 80 that are detachably stacked in a vertical direction, and a first spring 90 that supports the second blow valve 80 on the back surface. Each of the first blow valve 70 and the second blow valve 80 is biased to their respective closed positions. The pressure receiving area A1 at the closed position of the first blow valve 70 corresponds to the passage area of the small diameter passage 61. The pressure receiving area A <b> 2 at the closed position of the second blow valve 80 corresponds to the opening area of the inner recess 80 </ b> B of the cup-shaped body 80 </ b> A of the first blow valve 70. A1 is set smaller by A2. The opening limit of the first blow valve 70 is restricted by abutting against the stopper portion 51 </ b> A of the upper valve housing 51.

Accordingly, the hydraulic shock absorber 10 includes the compression side damping force adjusting device 50 and operates as follows.
(1) In the expansion / contraction stroke of the hydraulic shock absorber 10, when the piston moving speed V / P increases and the pressure in the rod side oil chamber 12A or the piston side oil chamber 12B increases, the extension side damping valve 33 and the pressure side damping valve 34 Opening (FIG. 3 (A)), the expansion side damping force TF and the compression side damping force CF shown by the solid line in FIG. 4 are generated. When the piston moving speed V / P is lower than a constant speed (for example, 1.0 m / s) (for example, 0.5 m / s, 0.7 m / s), the damping forces TF and CF of the expansion side damping valve 33 and the compression side damping valve 34 are As shown in FIG. 5, there is no extreme reduction during these steps.

  (2) In the compression stroke of the hydraulic shock absorber 10, the piston moving speed V / P further increases to reach a constant speed, the pressure in the piston side oil chamber 12B also increases, and the piston side oil chamber 12B acting on the bypass passage 60 When the pressure becomes the valve opening pressure of the first blow valve 70, the first blow valve 70 compresses and opens the spring 90 via the second blow valve 80, and the high pressure oil in the piston side oil chamber 12B is opened. The liquid is blown into the intermediate pressure chamber 62 between the second blow valve 80 and the damping force of the compression side damping valve 34 is lowered from the high damping force state (FIG. 3B). After the first blow valve 70 abuts against the stopper portion 51A of the upper valve housing 51 and reaches the opening limit, the pressure receiving area is larger than that of the first blow valve 70, so that the second blow valve having a low valve opening pressure is used. The valve 80 further compresses the spring and immediately opens away from the first blow valve 70 to blow the high-pressure oil in the piston side oil chamber 12B and the intermediate pressure chamber 62 from the communication passage 63 to the rod side oil chamber 12A. Then, the damping force of the compression side damping valve 34 is extremely lowered (FIG. 3C).

  (3) After the opening of the second blow valve 80 in the above (2), the pressures in the piston-side oil chamber 12B and the intermediate pressure chamber 62 are blown and lowered, and the second blow valve 80 is biased by the urging force of the spring 90. 80 moves to the closed position where it is stacked on the first blow valve 70. However, when the piston 24 continues the compression stroke, the pressure in the piston-side oil chamber 12B is maintained unless the first blow valve 70 is closed again. The second blow valve 80 having a large pressure receiving area is opened again while continuing to act on the intermediate pressure chamber 62 from the small diameter passage 61. Therefore, as a result of the second blow valve 80 being repeatedly opened and closed, the high pressure oil in the piston side oil chamber 12B and the intermediate pressure chamber 62 is blown from the communication passage 63 to the rod side oil chamber 12A, and the damping force of the pressure side damping valve 34 is increased. Continue to lower.

  As described above, the damping force CF of the compression side damping valve 34 is extremely lowered from the high damping force state as shown by a one-dot chain line in FIG. FIG. 5 shows that the damping force CF of the compression side damping valve 34 is extremely lowered during the compression side stroke when the piston moving speed V / P reaches, for example, 1.0 m / s. In the extreme reduction state of the pressure side damping force CF of the pressure side damping valve 34 shown in FIG. 4, P1 is an example in which the pressure receiving area of the first blow valve 70 is increased to reduce the valve opening pressure, and P2 is the first blow valve. In this example, the pressure receiving area of the valve 70 is reduced to increase the valve opening pressure. When the spring force of the spring 90 is large, the opening speed of the first and second blow valves 70, 80 is slowed down, and the damping force by the compression side damping valve 34 is slowly lowered (damping force characteristic R1 in FIG. 5). When the spring force of the spring 90 is small, the opening speed of the first and second blow valves 70 and 80 is increased, and the damping force by the compression side damping valve 34 is quickly reduced (damping force characteristic R2 in FIG. 5).

  Therefore, when a vehicle equipped with the hydraulic shock absorber 10 enters a parking lot or the like from a road, for example, when the wheels get over a step such as a curb stone, if the hydraulic shock absorber 10 is abruptly compressed, normally, the compression side damping force Suddenly rises, making it difficult to make a compression stroke, and a rugged ride. In the present invention, when the compression side damping force suddenly increases, the compression side first and second blow valves 70 and 80 of the compression side damping force adjusting device 50 are opened, and the damping force is extremely reduced. Because it absorbs the impact acting on the wheels, there is no rugged feeling and it rides lightly over the steps.

According to the present embodiment, the following operational effects can be obtained.
(a) When the piston moving speed reaches a constant speed due to the movement of the piston 24 and the pressure of the piston-side oil chamber 12B acting on the bypass passage 60 becomes the valve opening pressure of the first blow valve 70, the first blow valve 70 Compresses and opens the spring 90 via the second blow valve 80, blows the high-pressure oil in the piston side oil chamber 12B to the intermediate pressure chamber 62 between the second blow valve 80, and pressure side damping. The damping force of the valve 34 is lowered from the high damping force state. After the first blow valve 70 reaches the opening limit, the second blow valve 80 whose valve opening pressure is lower than that of the first blow valve 70 further compresses the spring 90 and immediately leaves the first blow valve 70. The high pressure fluid in the piston side oil chamber 12B and the intermediate pressure chamber 62 is blown to the rod side oil chamber 12A, and the damping force of the pressure side damping valve 34 is extremely lowered.

  (b) After the above-described (a) opening of the second blow valve 80, the pressure in the piston-side oil chamber 12B and the intermediate pressure chamber 62 blows and decreases, and the second blow valve 80 is biased by the biasing force of the spring 90. 80 moves to the closed position where it is stacked on the first blow valve 70, but when the piston 24 continues to move, the pressure in the piston-side oil chamber 12B is bypassed unless the first blow valve 70 is closed again. The second blow valve 80 having a large pressure receiving area is opened again while continuing to act on the intermediate pressure chamber 62 from the passage 60. Therefore, as a result of the second blow valve 80 being repeatedly opened and closed, the high pressure oil in the piston side oil chamber 12B and the intermediate pressure chamber 62 is blown into the rod side oil chamber 12A, and the damping force of the pressure side damping valve 34 is continuously lowered.

  (c) When a vehicle gets over a curb or the like (step) when entering a parking lot from a road, for example, in the general hydraulic shock absorber 10, the compression side damping force rapidly rises due to a sudden compression stroke, making it difficult to operate. In the hydraulic shock absorber 10 of the present invention, when the hydraulic fluid in the piston-side oil chamber 12B becomes a high pressure during an abrupt compression stroke, the first blow valve 70 and the second blow valve 80 are configured as described in (a) and (b) above. Thus, the damping force of the compression side damping valve 34 is lowered, and the step is lightly ridden without any lumpy feeling to absorb the impact and improve the riding comfort.

  (d) Since the damping force characteristic is controlled depending on the pressure in the piston-side oil chamber 12B, for example, the pressure in the piston-side oil chamber 12B increases during the compression stroke of the hydraulic shock absorber 10, and the pressure-side first and When the second blow valves 70 and 80 are opened and the damping force of the compression side damping valve 34 is extremely lowered from the high damping force state and then reversed to the extension stroke, the compression side first and second blow valves 70 and 80 are reversed. The extension side damping valve 33 generates a normal damping force.

  (e) By providing the first and second blow valves 70 and 80 on the pressure side, the damping force of the pressure side damping valve 34 can be extremely reduced when the hydraulic shock absorber 10 is compressed.

  (f) The first blow valve 70 and the second blow valve 80 bypass the compression side damping valve 34, and connect the rod side oil chamber 12A and the piston side oil chamber 12B defined by the piston 24 provided on the piston rod 13. The above-described (a) to (e) can be realized by the piston valve device 20 by being provided in the bypass path 60 that communicates.

Example 2 (FIGS. 6 to 8)
The hydraulic shock absorber 10 in FIG. 6 is different from the hydraulic shock absorber 10 in FIGS. 1 and 2 in that the communication passage 63 on the downstream side of the bypass passage 60 formed by the upper and lower valve housings 51 and 52 of the compression side damping force adjusting device 50. In addition, a check valve 64 that allows only the flow from the bypass passage 60 to the rod-side oil chamber 12A is provided. The check valve 64 of the present embodiment is configured by a disc valve-like check valve that is interposed between the washer 22 and the upper end surface of the upper valve housing 51 around the screw portion 21 of the piston rod 13. The check valve 64 may include an orifice-shaped passage that communicates the bypass passage 60 with the rod-side oil chamber 12A.

  The hydraulic shock absorber 10 of FIGS. 6 and 7 includes the check valve 64 in the compression side damping force adjusting device 50, so that the hydraulic shock absorber 10 of FIGS. It operates as follows.

  As in the hydraulic shock absorber 10 of FIGS. 2 and 3, the first blow valve 70 and the second blow valve 80 are opened in the compression stroke as described in (2) and (3) above, and the piston side oil When the high pressure oil in the chamber 12B and the intermediate compression chamber 62 is blown from the communication passage 63 to the rod side oil chamber 12A, the high pressure oil pushes the check valve 64 in the communication passage 63 and flows out to the rod side oil chamber 12A.

  Thereafter, when the hydraulic shock absorber 10 is reversed to the extension stroke, in the hydraulic shock absorber 10 of FIGS. 2 and 3, the high-pressure oil in the rod side oil chamber 12 </ b> A flows backward from the communication passage 63 to the bypass passage 60. The second blow valves 70 and 80 are immediately set to the closed position. However, in the hydraulic shock absorber 10 shown in FIGS. 6 and 7, the high-pressure oil in the rod side oil chamber 12 </ b> A is prevented from flowing back to the bypass path 60 by the check valve 64, and the second blow valve 80 is connected to the spring 90. It is closed gradually only by the urging force, and the closing speed of the second blow valve 80 is delayed. Therefore, when the unevenness (step) on the road surface on which the vehicle travels is repeated, the first blow valve 70 and the second blow valve 80 are sequentially opened in the compression stroke at the time of passing the first step, and the above (2) Realize (3). In the compression stroke at the time of passing the step after the second time, the closing speed of the second blow valve 80 is delayed due to the presence of the check valve 64 and the second blow valve 80 is not closed yet. As a result, the first blow valve 80 is not closed. The valve 70 is in an open state. Accordingly, in the compression stroke when the step passes after the second time, the oil in the piston side oil chamber 12B is smoothly blown into the rod side oil chamber 12A, and the damping force of the compression side damping valve 34 is low without increasing. It can be maintained (two-dot chain line in FIG. 8), and each step can be lightly ridden without any lumpy feeling to absorb the impact and improve riding comfort.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration of the present invention is not limited to this embodiment, and even if there is a design change or the like without departing from the gist of the present invention. It is included in the present invention. For example, the damping force adjusting structure of the present invention may be such that the first blow valve and the second blow valve blow when the hydraulic shock absorber is extended.

  In the damping force adjusting structure of the present invention, the first blow valve and the second blow valve bypass the damping valve, and the piston side oil chamber and the reservoir chamber defined by the bottom piece provided at the lower end of the cylinder It may be provided in a bypass route that communicates.

  In addition, the damping force adjusting structure of the present invention can be used as an impact force limit device because it reduces the damping force of the hydraulic shock absorber when a certain impact or more acts on the wheel.

1 is a schematic cross-sectional view showing a hydraulic shock absorber according to a first embodiment. FIG. 2 is a cross-sectional view showing the compression side damping force adjusting structure. FIG. 3 is a cross-sectional view showing the operation of the compression side damping force adjusting structure. FIG. 4 is a diagram showing the relationship between piston speed and damping force. FIG. 5 is a diagram showing a damping force adjustment result. FIG. 6 is a cross-sectional view showing the compression side damping force adjusting structure of the second embodiment. FIG. 7 is a cross-sectional view showing the operation of the compression side damping force adjusting structure. FIG. 8 is a diagram showing a damping force adjustment result.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Hydraulic buffer 12 Cylinder 12A Rod side oil chamber 12B Piston side oil chamber 12C Reservoir chamber 13 Piston rod 24 Piston 33 Extension side damping valve 34 Pressure side damping valve 50 Pressure side damping force adjustment device 60 Bypass path 64 Check valve 70 First blow Valve 80 Second blow valve 90 Spring

Claims (6)

Oil is stored in the oil chamber of the cylinder, the piston provided at the insertion end of the piston rod inserted into the cylinder is slidably fitted into the cylinder, and the pressure is increased from one oil chamber to the other. In the damping force adjustment structure of the hydraulic shock absorber that generates damping force by controlling the flow of oil liquid into the oil chamber of the
The first blow valve and the second blow valve that blow the pressurized oil in one oil chamber to the other oil chamber are sequentially connected to the bypass passage that bypasses the damping valve and connects the two oil chambers. Arranged in series,
The first blow valve and the second blow valve are detachably stacked, and the first blow valve and the second blow valve are brought into their closed positions by one spring that supports the second blow valve on the back surface. The hydraulic pressure is biased, and the pressure receiving area of the first blow valve in the closed position is set smaller than the pressure receiving area of the second blow valve, and the opening limit of the first blow valve is restricted. Damping force adjustment structure of the shock absorber.   The damping force adjusting structure for a hydraulic shock absorber according to claim 1, wherein a check valve that allows only a flow from the bypass passage to the oil chamber is provided on the downstream side of the second blow valve in the bypass passage.   3. The hydraulic shock absorber damping force adjusting structure according to claim 1, wherein the first blow valve and the second blow valve blow when the hydraulic shock absorber is compressed.   The damping force adjusting structure for a hydraulic shock absorber according to claim 1 or 2, wherein the first blow valve and the second blow valve blow when the hydraulic shock absorber is extended.   The first blow valve and the second blow valve are provided in a bypass passage that bypasses the damping valve and connects the rod-side oil chamber and the piston-side oil chamber defined by a piston provided in the piston rod. The damping force adjustment structure of the hydraulic shock absorber according to any one of?   The first blow valve and the second blow valve are provided in a bypass passage that bypasses the damping valve and connects the piston-side oil chamber and the reservoir chamber defined by the bottom piece provided at the lower end portion of the cylinder. The damping force adjustment structure of the hydraulic shock absorber according to any one of 1 to 4.

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