DAMPING VALVE AND SHOCK ABSORBER

A damping valve of the present invention includes: a partition wall body that is annular, and is inserted into a cylindrical body, is radially positioned only by the cylindrical body, and has an annular outer circumferential valve seat protruding axially from an axial one end and a port provided on an inner circumferential side of the outer circumferential valve seat; a valve stopper having an annular inner circumferential valve seat facing the one end of the partition wall body and having an outer diameter smaller than that of the outer circumferential valve seat; and an annular leaf valve that is interposed between the outer circumferential valve seat and the inner circumferential valve seat and is set to be open to both the inside and the outside to open and close the port, wherein the partition wall body includes an aligning portion that aligns the leaf valve with respect to the outer circumferential valve seat.

TECHNICAL FIELD

The present invention relates to a damping valve and a shock absorber.

BACKGROUND ART

The shock absorber includes, for example, a cylinder, a piston movably inserted into the cylinder, and a piston rod movably inserted into the cylinder and connected to the piston, and is interposed between a vehicle body and a wheel of a vehicle and exerts a damping force to suppress the vibration of the vehicle body and the wheel. The damping force exerted by the shock absorber is exerted by the damping valve and affects ride comfort in the vehicle. In recent years, there is a demand for the exertion of a sufficient damping force to suppress the vibration in the shock absorber used for a suspension of the vehicle even when extending or contracting at an extremely low speed in order to improve the ride comfort.

In order to meet such a demand, for example, as disclosed in WO 2021/084956, the damping valve may include: a valve disc that is annular and loosely fitted to an outer circumference of the piston rod, is movably mounted in the axial direction, and has a port and an outer circumferential valve seat surrounding the outer circumference of the port; a valve stopper that is fixed to the piston rod, faces the valve disc axially, and has an inner circumferential valve seat that is annular and has an outer diameter smaller than an inner diameter of the outer circumferential valve seat; and a leaf valve that is interposed between the outer circumferential valve seat and the inner circumferential valve seat and is set to be open to both the inside and the outside. The damping valve exerts a damping force when the leaf valve gives resistance to the flow of the hydraulic oil passing through the port while the shock absorber extends and contracts at an extremely low speed.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

In the damping valve configured as described above, since the valve disc is loosely fitted to the piston rod and is slidably in contact with the inner circumference of the cylinder, the valve disc may be offset radially with respect to the piston rod. On the other hand, since the leaf valve is aligned with respect to the piston rod, when the valve disc is axially offset with respect to the piston rod, the leaf valve is eccentrically seated on the outer circumferential valve seat provided on the valve disc.

When the leaf valve is eccentrically seated with respect to the outer circumferential valve seat of the valve disc, the deflection of the leaf valve is not circumferentially uniform, and a gap may be formed between the leaf valve and the outer circumferential valve seat although the leaf valve is seated on the outer circumferential valve seat.

In such a situation, when the shock absorber extends and contracts at an extremely low speed, the hydraulic oil passes through the gap formed between the leaf valve and the outer circumferential valve seat, and the damping force is reduced, and thus it is difficult to exert a damping force of a desired magnitude, and it is impossible to obtain damping force characteristics (characteristics of the damping force generated by the shock absorber with respect to the extension and contraction speed of the shock absorber) that are good for suppressing the vibration when the shock absorber extends and contracts at an extremely low speed.

Therefore, an object of the present invention is to provide a damping valve and a shock absorber capable of exerting a sufficient damping force even when the shock absorber extends and contracts at an extremely low speed and obtaining good damping force characteristics for suppressing such extension and contraction.

Solution to Problem

In order to solve the above problem, a damping valve of the present invention includes: a partition wall body that is annular, is inserted into a cylindrical body, is radially positioned only by the cylindrical body, and has an annular outer circumferential valve seat protruding axially from axial one end and a port provided on an inner circumferential side of the outer circumferential valve seat; a valve stopper that has an annular inner circumferential valve seat facing the one end of the partition wall body and having an outer diameter smaller than that of the outer circumferential valve seat; and an annular leaf valve that is interposed between the outer circumferential valve seat and the inner circumferential valve seat and is set to be open to both the inside and the outside to open and close the port, wherein the partition wall body includes an aligning portion that aligns the leaf valve with respect to the outer circumferential valve seat.

In the damping valve configured as described above, since the leaf valve is aligned with respect to the outer circumferential valve seat by the aligning portion provided in the partition wall body radially positioned only by the cylindrical body, in a state where the leaf valve is seated on the outer circumferential valve seat and the inner circumferential valve seat, a gap is not formed between an outer circumference of the leaf valve and the outer circumferential valve seat, and a gap that affects the damping force is also not formed between an inner circumference of the leaf valve and the inner circumferential valve seat. Therefore, according to the damping valve, it is possible to prevent leakage of liquid from the gap, and generate a sufficient damping force in the shock absorber even when the flow rate of the liquid passing through the port is small.

DESCRIPTION OF EMBODIMENTS

Hereinafter, the present invention will be described based on the embodiments illustrated in the drawings. As illustrated inFIGS.1and2, a damping valve V1in one embodiment includes: a sub-piston2as a partition wall body that is annular and is inserted into a cylinder1as a cylindrical body, is radially positioned only by the cylinder1, and has an annular outer circumferential valve seat2cand a port2d; a valve stopper3having an annular inner circumferential valve seat3cfacing one end2bof the sub-piston2; and an annular leaf valve4that is interposed between the outer circumferential valve seat2cand the inner circumferential valve seat3cand is set to be open to both the inside and the outside to open and close the port2d, wherein the damping valve V1is applied to a shock absorber D.

On the other hand, the shock absorber D to which the damping valve V1is applied includes a cylinder1, a piston rod5that is inserted into the cylinder1so as to be axially movable, a piston6as a main partition wall body that is attached to the piston rod5and is inserted into the cylinder1so as to be axially movable, main valves7and8that open and close main ports6aand6bprovided in the piston6, and the damping valve V1. Further, in the case of the shock absorber D, for example, it is used by being interposed between a vehicle body and an axle of a vehicle, which is not illustrated, to suppress vibrations of the vehicle body and the wheels.

Hereinafter, some components in the damping valve V1and the shock absorber D will be described in detail. As illustrated inFIG.1, an annular rod guide20is mounted on the upper end of the cylinder1, and the lower end of the cylinder1is closed by a cap14. Then, in the cylinder1, the piston rod5having a distal end to which the piston6and the sub-piston2are mounted is movably inserted.

The piston rod5is slidably inserted into the rod guide20and inserted into the cylinder1so as to axially movable, and axial movement is guided by the rod guide20. In addition, the inside of the cylinder1is partitioned by the piston6and the sub-piston2into an extension side chamber R1and a compression side chamber R2that are filled with liquid. Note that, although the liquid is the hydraulic oil in the embodiment of the present embodiment, it is also possible to use liquid such as water and an aqueous solution in addition to the hydraulic oil, for example.

Note that a gas chamber G is defined inside the cylinder1below the compression side chamber R2by a free piston9slidably inserted into the cylinder1. Further, when the piston rod5is displaced axially with respect to the cylinder1, the free piston9is displaced axially with respect to the cylinder1to be extended or contracted in the gas chamber G in response to a change of the volume of the piston rod5inside the cylinder1, and the volume of the piston rod5moving in and out of the cylinder1is compensated by a change of the volume of the gas chamber G. In this manner, the shock absorber D is a so-called monotube shock absorber, but may be configured as a double cylinder type shock absorber including a reservoir outside the cylinder1.

Returning to the above, the piston rod5includes a small-diameter portion5aprovided at the distal end which is the lower end inFIG.1, a screw portion5bprovided on an outer circumference of a distal end of the small-diameter portion5a, and a stepped portion5cformed by providing the small-diameter portion5a, and the annular piston6and the sub-piston2are mounted on the outer circumference of the small-diameter portion5a.

The piston6is annular, is fixed to the outer circumference of the small-diameter portion5a, and has an outer circumference slidably in contact with an inner circumference of the cylinder1. In addition, the piston6includes a compression side main port6aand an extension side main port6bas main ports. The sub-piston2has an outer circumference slidably in contact with the inner circumference of the cylinder1, and includes the port2d. The piston6and the sub-piston2face each other while being separated axially from each other, and cooperatively partition the inside of the cylinder1into the extension side chamber R1and the compression side chamber R2, and an intermediate chamber R3is formed between the piston6and the sub-piston2. The intermediate chamber R3communicates with the compression side chamber R2through the compression side main port6aand the extension side main port6bprovided in the piston6, and communicates with the extension side chamber R1through the port2dprovided in the sub-piston2. Thus, the compression side main port6a, the extension side main port6b, the intermediate chamber R3, and the port2dform a passage that causes the extension side chamber R1and the compression side chamber R2to communicate with each other.

Further, the valve stopper3, the leaf valve4, a spacer10, a tubular collar11, the sub-piston2, a main valve stopper12, a compression side main leaf valve7as a main leaf valve, the piston6, and an extension side main leaf valve8as the main leaf valve are mounted to the outer circumference of the small-diameter portion5aof the piston rod5as illustrated inFIGS.1and2. Further, the valve stopper3, the spacer10, the collar11, the main valve stopper12, the compression side main leaf valve7, the piston6, and the extension side main leaf valve8are sandwiched and fixed by the stepped portion5cof the piston rod5and a piston nut13screwed to the screw portion5b.

As illustrated inFIG.2, the valve stopper3includes a fitting portion3athat is annular and has a reduced inner diameter on the lower end side inFIG.2, a flange portion3bprotruding from an outer circumference of the upper end inFIG.2of the fitting portion3atoward an outer circumferential side, and an annular inner circumferential valve seat3cformed on an outer circumference of the lower end inFIG.2of the flange portion3bfacing the sub-piston2. The inner diameter of the fitting portion3aon the lower end side inFIG.2is set to be fitted to the outer circumference of the small-diameter portion5aof the piston rod5, and the inner diameter of the fitting portion3aon the upper end side inFIG.2is larger than an outer diameter of the piston rod5on the upper side inFIG.2of the small-diameter portion5a. Thus, when the valve stopper3is fitted to the small-diameter portion5aof the piston rod5, an inner circumference of the fitting portion3aon the lower end side is fitted to the small-diameter portion5aof the piston rod5, and thus the valve stopper3is radially positioned with respect to the piston rod5, while a stepped portion at a boundary between the lower end and the upper end of the fitting portion3aabuts on the stepped portion5cof the piston rod5, and thus the valve stopper3is axially positioned with respect to the piston rod5.

In the present embodiment, the spacer10is formed of a plurality of annular plates whose outer diameter is set to be larger than an outer diameter of the collar11and whose inner diameter is set to a diameter that can be fitted to the small-diameter portion5aof the piston rod5, and is fitted to the outer circumference of the small-diameter portion5aof the piston rod5. An axial position of the collar11with respect to the piston rod5and the position of the movement limit of the sub-piston2to the upper side inFIG.2can be adjusted by adjusting the number of stacked annular plates constituting the spacer10. Therefore, if the adjustment of the position of the collar11is not required and the movement limit of the sub-piston2is restricted by the fitting portion3aof the valve stopper3, the spacer10can be omitted, and the collar11may be formed of a single annular plate depending on the position of the collar.

The collar11is a cylindrical component whose outer diameter is set to be smaller than outer diameters of the spacer10and the fitting portion3aof the valve stopper3and whose inner diameter is set to a diameter that can be fitted to the small-diameter portion5aof the piston rod5, and is fitted to the outer circumference of the small-diameter portion5aof the piston rod5.

The sub-piston2is annular, has an outer diameter set to a diameter slidably in contact with the inner circumference of the cylinder1, has an inner diameter set to a diameter larger than the outer diameter of the collar11, and is loosely fitted to the outer circumference of the collar11.

Specifically, the sub-piston2includes an annular main body2a, an annular outer circumferential valve seat2cprotruding axially from the one end2bthat is an axial upper end inFIG.2of the main body2a, a plurality of ports2dprovided side by side on the same circumference on the inner circumferential side of the outer circumferential valve seat2cin the main body2a, an annular protrusion2eprotruding axially from an outer circumferential side of the one end2bof the main body2awith respect to the outer circumferential valve seat2c, and a piston ring2fmounted on an outer circumference of the main body2aand slidably in contact with the inner circumference of the cylinder1.

An axial height of the one end2bof the main body2aincreases from the inner circumference toward the outer circumference, and an axial length of the main body2aon the inner circumferential side is slightly shorter than an axial length of the collar11.

As described above, the ports2dare arranged at equal intervals on the same circumference concentric with respect to the main body2a, and cause the intermediate chamber R3between the sub-piston2and the piston6to communicate with the extension side chamber R1through the main body2a.

The outer circumferential valve seat2cprotrudes axially from the main body2atoward the upper side inFIG.2so as to surround an outer circumference of the port2d, and is arranged on the upper side inFIG.2with respect to the inner circumferential valve seat3cprovided in the flange portion3bof the valve stopper3. In addition, an inner diameter of the outer circumferential valve seat2cis larger than an outer diameter of the inner circumferential valve seat3cof the valve stopper3.

The protrusion2eis annular and protrudes axially toward the upper side inFIG.2from an outer circumference of the outer circumferential valve seat2c, and surrounds the outer circumferential valve seat2c. Note that the protrusion2emay not be annular, and may be installed in a plural number on the same circumference surrounding the outer circumferential valve seat2c.

When the sub-piston2is loosely fitted to the collar11, a gap is formed between the inner circumference of the sub-piston2and the collar11, and thus the sub-piston2is radially movable with respect to the collar11. In addition, since the axial length of the inner circumference of the sub-piston2is shorter than the axial length of the collar11, the sub-piston2can be slightly displaced in the vertical direction inFIG.2, which is the axial direction, between the spacer10and the main valve stopper12. Furthermore, when the sub-piston2is inserted into the cylinder1, an outer circumference of the piston ring2fis slidably in contact with the inner circumference of the cylinder1, and the sub-piston2is loosely fitted to the collar11, and thus the sub-piston2is radially positioned only by the cylinder1. When the sub-piston2is loosely fitted to the outer circumference of the collar11, the inner circumferential valve seat3cof the valve stopper3faces the inner circumferential side of the main body2aof the sub-piston2.

The leaf valve4is annular, has an inner diameter smaller than the outer diameter of the inner circumferential valve seat3cand larger than the outer diameter of the fitting portion3aof the valve stopper3, and has an outer diameter set such that the outer circumference of the leaf valve4abuts on the protrusion2earranged on the outer circumferential side of the outer circumferential valve seat2c. Since the outer circumference of the leaf valve4abuts on the annular protrusion2eof the sub-piston2, the leaf valve4is aligned with respect to the outer circumferential valve seat2cof the sub-piston2by the protrusion2eand is radially positioned so as to be concentric with the outer circumferential valve seat2c. In this manner, the protrusion2efunctions as an aligning portion that aligns the leaf valve4with respect to the outer circumferential valve seat2c. In addition, the inner diameter of the leaf valve4is larger than the outer diameter of the fitting portion3ato such an extent that the inner circumferential surface of the leaf valve4does not come into contact with the fitting portion3aof the facing valve stopper3even when being aligned by the protrusion2e. Therefore, consideration is taken so that the alignment of the leaf valve4by the protrusion2eis not disturbed by the valve stopper3.

Note that, as described above, the protrusion2emay not be annular as long as the leaf valve4can be aligned so as to be concentric with the outer circumferential valve seat2c, and thus a plurality of protrusions2emay be provided at intervals on the same circumference surrounding the outer circumferential valve seat2c. In addition, the shape of the protrusion2ecan also be modified in any manner as long as the leaf valve4can be aligned so as to be concentric with the outer circumferential valve seat2c.

The leaf valve4is interposed between the inner circumferential valve seat3cand the outer circumferential valve seat2cin a state where the upper end inFIG.2of the inner circumference is seated on the inner circumferential valve seat3cand the lower end inFIG.2of the outer circumference is seated on the outer circumferential valve seat2c. The leaf valve4receives pressure from the extension side chamber R1side, and its inner circumferential side is deflected to the lower side inFIG.2with its outer circumference supported by the outer circumferential valve seat2cas a fulcrum, and is separated from the inner circumferential valve seat3cof the valve stopper3to cause the port2dto communicate with the compression side chamber R2. On the other hand, the leaf valve4receives pressure from the intermediate chamber R3side, and its outer circumferential side is deflected to the upper side inFIG.2with its inner circumference supported by the inner circumferential valve seat3cas a fulcrum, and is separated from the outer circumferential valve seat2cof the sub-piston2to cause the port2dto communicate with the extension side chamber R1.

As described above, the leaf valve4functions as a de Carbon valve that is open to both the inside and the outside in which the valve opens by separating from the inner circumferential valve seat3cwhen the pressure of the extension side chamber R1becomes higher than the pressure of the intermediate chamber R3and the differential pressure between the two chambers reaches a valve opening pressure, and the valve opens by separating from the outer circumferential valve seat2cwhen the pressure of the intermediate chamber R3becomes higher than the pressure of the extension side chamber R1and the differential pressure between the two chambers reaches the valve opening pressure. Since the axial height of the main body2ain the sub-piston2decreases as it goes toward the inner circumference, a sufficient space such that the inner circumference of the leaf valve4can be deflected to the lower side inFIG.2is secured between the inner circumferential valve seat3cand the main body2aof the sub-piston2.

In addition, since the outer circumferential valve seat2cof the sub-piston2is arranged at a higher position inFIG.2than the inner circumferential valve seat3cof the valve stopper3, the leaf valve4is given an initial deflection when interposed between the inner circumferential valve seat3cand the outer circumferential valve seat2c, and presses the inner circumferential valve seat3cand the outer circumferential valve seat2cwith a resilient force generated by the leaf valve4itself. Since the leaf valve4is given the initial deflection in this manner, a valve opening pressure at which the leaf valve4is separated from the inner circumferential valve seat3cand the outer circumferential valve seat2cis set, and thus the valve opening pressure can be adjusted by adjusting the initial deflection amount. Note that, since the initial deflection amount given to the leaf valve4can be adjusted by the difference in the axial distance between the inner circumferential valve seat3cand the outer circumferential valve seat2c, the valve opening pressure can be adjusted by adjusting the thickness of the annular plate of the spacer10and the number of stacked plates.

The main valve stopper12has a circular annular shape, has an inner diameter set to a diameter that can be fitted to the small-diameter portion5aof the piston rod5, and is fitted to the small-diameter portion5aof the piston rod5. The main valve stopper12includes a relief portion12aformed of an annular recess on an outer circumference of an end facing the sub-piston2, and the installation of the relief portion12acauses the main valve stopper12not to close the port2deven when it faces the port2dof the sub-piston2.

Subsequently, the compression side main leaf valve7is a stacked leaf valve formed by stacking a plurality of annular plates having an inner diameter set to a diameter that can be fitted to the small-diameter portion5aof the piston rod5, and placed on the upper end inFIG.2of the piston6to open and close an outlet end of the compression side main port6a. An orifice7aformed by a notch is provided on an outer circumference of the annular plate of the compression side main leaf valve7facing the piston6. In the compression side main leaf valve7, the inner circumferential side is sandwiched between the piston nut13and the stepped portion5c, and only deflection on the outer circumferential side is permitted.

Further, the compression side main leaf valve7causes the compression side chamber R2and the intermediate chamber R3to communicate with each other only through the orifice7ain a state of being entirely in contact with the piston6, and is deflected to open the compression side main port6awhen the pressure of the compression side chamber R2received through the compression side main port6abecomes higher than the pressure of the intermediate chamber R3and a differential pressure therebetween reaches a valve opening pressure. The valve opening pressure of the compression side main leaf valve7is set higher than the valve opening pressure of the leaf valve4. Note that an outer diameter of the annular plate forming the compression side main leaf valve7can be modified in any manner according to the setting of resistance given to the flow of hydraulic oil passing through the compression side main port6aby the compression side main leaf valve7.

The extension side main leaf valve8is a stacked leaf valve formed by stacking a plurality of annular plates having an inner diameter set to a diameter that can be fitted to the small-diameter portion5aof the piston rod5, and placed on the lower end inFIG.2of the piston6to open and close an outlet end of the extension side main port6b. An orifice8aformed by a notch is provided on an outer circumference of the annular plate of the extension side main leaf valve8facing the piston6. In the extension side main leaf valve8, the inner circumferential side is sandwiched between the piston nut13and the stepped portion5c, and only deflection on the outer circumferential side is permitted.

Further, the extension side main leaf valve8causes the intermediate chamber R3and the compression side chamber R2to communicate with each other only through the orifice8ain a state of being entirely in contact with the piston6, and is deflected to open the extension side main port6bwhen the pressure of the intermediate chamber R3becomes higher than the pressure of the compression side chamber R2received through the extension side main port6band the differential pressure therebetween reaches the valve opening pressure. The valve opening pressure of the extension side main leaf valve8is set higher than the valve opening pressure of the leaf valve4. Note that an outer diameter of the annular plate forming the extension side main leaf valve8can be modified in any manner according to the setting of resistance given to the flow of hydraulic oil passing through the extension side main port6bby the extension side main leaf valve8.

As described above, the damping valve V1includes: the sub-piston2as a partition wall body that is annular, and is inserted into the cylinder1as a cylindrical body, is radially positioned only by the cylinder1, and has the annular outer circumferential valve seat2cprotruding axially from the axial one end2band the port2dprovided on the inner circumferential side of the outer circumferential valve seat2c; the valve stopper3having the annular inner circumferential valve seat3cfacing the one end2bof the sub-piston2and having an outer diameter smaller than that of the outer circumferential valve seat2c; and the annular leaf valve4that is interposed between the outer circumferential valve seat2cand the inner circumferential valve seat3cand is set to be open to both the inside and the outside to open and close the port2d. In addition, the sub-piston2of the damping valve V1includes the protrusion2eas an aligning portion that aligns the leaf valve4with respect to the outer circumferential valve seat2c.

Hereinafter, an operation of the damping valve V1and the shock absorber D will be described. First, an operation when the piston rod5moves to the upper side inFIG.1with respect to the cylinder1and the shock absorber D performs an extension operation will be described. When the shock absorber D performs the extension operation, the piston6and the sub-piston2move to the upper side inFIG.1with respect to the cylinder1, and thus, the extension side chamber R1is compressed and the compression side chamber R2is enlarged.

Then, when the pressure in the extension side chamber R1increases and the difference between the pressure in the extension side chamber R1and the pressure in the intermediate chamber R3reaches the valve opening pressure of the leaf valve4, the leaf valve4deflects its inner circumferential side to the lower side inFIG.2, separates from the inner circumferential valve seat3c, and opens the port2dof the sub-piston2.

In a state where the extension speed of the shock absorber D is an extremely low speed and the extension side main leaf valve8is not opened, the hydraulic oil in the extension side chamber R1deflects the inner circumference of the leaf valve4, passes through the port2d, passes through the intermediate chamber R3, passes through the main ports6aand6bon the compression side and the extension side and the orifices7aand8a, and moves to the compression side chamber R2.

In this manner, when the extension speed of the shock absorber D is within an extremely low speed range during the extension operation, a flow rate of the hydraulic oil passing through the orifices7aand8ais very small, and thus, a pressure loss generated when the hydraulic oil passes through the leaf valve4is larger than a pressure loss generated when the hydraulic oil passes through the orifices7aand8a. Thus, the damping force is exerted mainly by the leaf valve4when the shock absorber D extends in the extremely low speed range.

In addition, when the extension speed of the shock absorber D is within a low speed range, the extension side main leaf valve8is not opened, but the pressure loss in the orifices7aand8aincreases, and thus, the shock absorber D exerts the damping force with the leaf valve4and the orifices7aand8a.

Furthermore, when the extension speed of the shock absorber D becomes high during the extension operation, the extension side main leaf valve8is deflected and opened to largely open the extension side main port6b, and the shock absorber D exerts the damping force mainly with the leaf valve4and the extension side main leaf valve8.

Next, an operation when the piston rod5moves to the lower side inFIG.1with respect to the cylinder1and the shock absorber D performs a contraction operation will be described. When the shock absorber D performs the contraction operation, the piston6and the sub-piston2move to the lower side inFIG.1with respect to the cylinder1, and thus, the compression side chamber R2is compressed, and the extension side chamber R1is enlarged.

Then, the pressure in the compression side chamber R2increases, and the hydraulic oil in the compression side chamber R2moves to the intermediate chamber R3via the compression side and extension side main ports6aand6band the orifices7aand8awhen the compression side main leaf valve7is closed, and mainly via the compression side main port6awhen the compression side main leaf valve7is open. When the difference between the pressure in the intermediate chamber R3and the pressure in the extension side chamber R1reaches the valve opening pressure of the leaf valve4, the leaf valve4deflects its outer circumferential side to the upper side inFIG.2, separates from the outer circumferential valve seat2c, and opens the port2dof the sub-piston2.

In a state where the extension speed of the shock absorber D is an extremely low speed and the compression side main leaf valve7is not opened, the hydraulic oil in the compression side chamber R2passes through the main ports6aand6bon the compression side and the extension side and the orifices7aand8a, passes through the intermediate chamber R3, deflects the outer circumference of the leaf valve4and passes through the port2d, and moves to the extension side chamber R1.

In this manner, when the contraction speed of the shock absorber D is within an extremely low speed range during the contraction operation, a flow rate of the hydraulic oil passing through the orifices7aand8ais very small, and thus, a pressure loss generated when the hydraulic oil passes through the leaf valve4is larger than a pressure loss generated when the hydraulic oil passes through the orifices7aand8a. Thus, the damping force is exerted mainly by the leaf valve4when the shock absorber D contracts in the extremely low speed range. Note that an inner circumferential surface of the protrusion2eis a tapered surface inclined such that the distal end side that is the axial upper end is tapered, and thus, when the outer circumferential side of the leaf valve4is deflected and separated from the outer circumferential valve seat2c, the flow path area formed by an annular gap generated between the outer circumferential valve seat2cand the leaf valve4is not limited due to the presence of the protrusion2e, so that the damping force after the opening of the leaf valve4does not become excessive. When there is a risk that the flow path area after the opening of the leaf valve4is limited by the protrusion2e, a plurality of protrusions2emay be provided at intervals on the outer circumferential side of the outer circumferential valve seat2c, instead of forming the protrusion2einto an annular shape, to prevent the protrusion2efrom limiting the flow path area.

In addition, when the contraction speed of the shock absorber D is within a low speed range, the compression side main leaf valve7is not opened, but the pressure loss in the orifices7aand8aincreases, and thus, the shock absorber D exerts the damping force with the leaf valve4and the orifices7aand8a.

Furthermore, when the extension speed of the shock absorber D becomes high during the extension operation, the compression side main leaf valve7is deflected and opened to largely open the compression side main port6a, and the shock absorber D exerts the damping force mainly with the leaf valve4and the compression side main leaf valve7.

Note that a speed range in which the damping force is generated mainly by the leaf valve4is set as an extremely low speed, a speed range in which the damping force is generated mainly by the orifices7aand8ais set as a low speed, and a speed range in which the damping force is generated mainly by the compression side main leaf valve7or the extension side main leaf valve8is set as a high speed in the shock absorber D of the present embodiment as described above. Moreover, the speed for classifying the extremely low speed, the low speed, and the high speed can be set optionally by the designer. In addition, any one of the orifices7aand8acan be omitted, and the orifices7aand8amay be provided not in the compression side main leaf valve7and the extension side main leaf valve8but in the piston6.

Here, the leaf valve4is aligned so as to be concentric with the outer circumferential valve seat2cof the sub-piston2radially positioned by the cylinder1, with the protrusion2efunctioning as the aligning portion of the sub-piston2. Since the leaf valve4is aligned so as to be concentric with the outer circumferential valve seat2cin this manner, it is possible to prevent a gap from being formed between the outer circumference of the leaf valve4to which the initial deflection is given due to the height difference between the outer circumferential valve seat2cand the inner circumferential valve seat3c, and the outer circumferential valve seat2c. On the other hand, the valve stopper3having the inner circumferential valve seat3cis fitted to the piston rod5and radially positioned with reference to the piston rod5. Thus, the leaf valve4radially positioned via the sub-piston2with reference to the cylinder1and the inner circumferential valve seat3cradially positioned with reference to the piston rod5may be eccentric. It has been found through a research by the inventors that even if the annular leaf valve4is eccentric with respect to the inner circumferential valve seat3c, a gap that greatly affects the damping force is not formed between the inner circumference of the leaf valve4and the inner circumferential valve seat3c.

Therefore, in a state where the leaf valve4is seated on the outer circumferential valve seat2cand the inner circumferential valve seat3c, a gap is not formed between the outer circumference of the leaf valve4and the outer circumferential valve seat2c, and even if the annular leaf valve4becomes eccentric with respect to the inner circumferential valve seat3c, a gap that greatly affects the damping force is not formed between the inner circumference of the leaf valve4and the inner circumferential valve seat3c. From the above, the damping force characteristics when the shock absorber D including the damping valve V1performs the extension/contraction operation at an extremely low speed are, as illustrated inFIG.3, characteristics such that a damping force having a sufficient height to suppress the extension/contraction of the shock absorber D is exerted from the start of the movement of the shock absorber D. Note that the damping force characteristics when the shock absorber including a conventional damping valve in which a gap is generated between the leaf valve and the outer circumferential valve seat in a state where the leaf valve is seated on the outer circumferential valve seat, extends and contracts at an extremely low speed are, as indicated by the broken line inFIG.3, characteristics such that the damping force is insufficient to suppress the extension and contraction of the shock absorber, whereas the shock absorber D of the present embodiment can exert a high damping force capable of suppressing the extension and contraction when the shock absorber D extends and contracts at an extremely low speed.

From the above, the shock absorber D is capable of exerting a sufficient damping force even when the shock absorber D extends and contracts at an extremely low speed, and obtaining good damping force characteristics for suppressing the extension and contraction when the shock absorber D extends and contracts at an extremely low speed.

In addition, when the shock absorber D repeats extension and contraction at an extremely low speed, the compression side main leaf valve7and the extension side main leaf valve8are not opened, and the leaf valve4opens and closes the port2d. In this manner, when the shock absorber D repeats extension and contraction at an extremely low speed and the shock absorber D is switched from the extension operation to the contraction operation, the sub-piston2is separated from the spacer10by the action of the pressure of the extension side chamber R1during the extension operation, and the inner circumference of the leaf valve4is deflected and separated from the inner circumferential valve seat3c. When an extension/contraction direction of the shock absorber D changes from this state to contraction, the leaf valve4receives the action of the compression side chamber R2and returns to a position abutting on the inner circumferential valve seat3cby its own restoring force, but an impact of a collision of the leaf valve4with the inner circumferential valve seat3cis not transmitted to the piston rod5since the sub-piston2is separated from the spacer10. In addition, when the shock absorber D repeats extension and contraction at an extremely low speed and the shock absorber D switches from the contraction operation to the extension operation, the sub-piston2is separated from the main valve stopper12by the action of the pressure of the intermediate chamber R3during the contraction operation, and the outer circumference of the leaf valve4is deflected and separated from the outer circumferential valve seat2c. When the extension/contraction direction of the shock absorber D changes from this state to extension, the leaf valve4receives the action of the extension side chamber R1and returns to a position abutting on the outer circumferential valve seat2cby its own restoring force, but an impact of a collision of the leaf valve4with the outer circumferential valve seat2cis not transmitted to the piston rod5since the sub-piston2is separated from the main valve stopper12.

In this manner, in the shock absorber D of the present embodiment, the impact generated when the leaf valve4separated from one of the outer circumferential valve seat2cand the inner circumferential valve seat3cis seated on one of the outer circumferential valve seat2cand the inner circumferential valve seat3cis not transmitted to the piston rod5, and accordingly, vibration is not applied to the vehicle body.

In addition, in the shock absorber D of the present embodiment, the sub-piston2is axially biased in the state where the leaf valve4is seated on the outer circumferential valve seat2cand the inner circumferential valve seat3e, the sub-piston2can be returned to the original position (position where the sub-piston2abuts on the main valve stopper12) even if moving in a direction opposite to a biasing direction of the leaf valve4, and there is no problem that the port2dcannot be blocked but is left open regardless of the position of the sub-piston2. Thus, according to the shock absorber D configured as described above, the damping force as set can be exerted even when the shock absorber extends or contracts at an extremely low speed, and there is no risk that the damping force becomes insufficient to degrade the ride comfort.

As described above, the damping valve V1of the present embodiment includes: the sub-piston (partition wall body)2that is annular, and is inserted into the cylinder (cylindrical body)1, is radially positioned only by the cylinder (cylindrical body)1, and has the annular outer circumferential valve seat2cprotruding axially from the axial one end2band the port2dprovided on the inner circumferential side of the outer circumferential valve seat2c; the valve stopper3having the annular inner circumferential valve seat3cfacing the one end2bof the sub-piston (partition wall body)2and having an outer diameter smaller than that of the outer circumferential valve seat2c; and the annular leaf valve4that is interposed between the outer circumferential valve seat2cand the inner circumferential valve seat3cand is set to be open to both the inside and the outside to open and close the port2d, wherein the sub-piston (partition wall body)2includes the protrusion (aligning portion)2ethat aligns the leaf valve4with respect to the outer circumferential valve seat2c.

In the damping valve V1configured as described above, since the leaf valve4is aligned with respect to the outer circumferential valve seat2cby the protrusion (aligning portion)2eprovided in the sub-piston (partition wall body)2radially positioned only by the cylinder (cylindrical body)1, in a state where the leaf valve4is seated on the outer circumferential valve seat2cand the inner circumferential valve seat3c, a gap is not formed between the outer circumference of the leaf valve4and the outer circumferential valve seat2c, and a gap that affects the damping force is also not formed between the inner circumference of the leaf valve4and the inner circumferential valve seat3c. According to the damping valve V1of the present embodiment, it is possible to prevent the leakage of the hydraulic oil from the gap, and generate a sufficient damping force in the shock absorber D even when the flow rate of the hydraulic oil passing through the port2dis small. Therefore, according to the damping valve V1of the present embodiment, it is possible to obtain good damping force characteristics for suppressing the extension and contraction even when the shock absorber D extends and contracts at an extremely low speed.

In addition, in the damping valve V1of the present embodiment, the aligning portion provided in the sub-piston (partition wall body)2is the protrusion2ethat protrudes axially from the outer circumferential side of the one end2bof the sub-piston (partition wall body)2with respect to the outer circumferential valve seat2cand abuts on the outer circumference of the leaf valve4. In this manner, when the protrusion2eprovided in close proximity to the outer circumferential valve seat2cis used as the aligning portion, the alignment accuracy of the leaf valve4with respect to the outer circumferential valve seat2cimproves.

Furthermore, the damping valve V1of the present embodiment is configured to include: the piston (main partition wall body)6that is inserted into the cylinder (cylindrical body)1so as to face the sub-piston (partition wall body)2axially and includes the compression side main port (main port)6aand the extension side main port (main port)6b; and the main valve that is formed of the compression side main leaf valve7that opens and closes the compression side main port (main port)6aand is set to a higher valve opening pressure than the valve opening pressure of the leaf valve4, and the extension side main leaf valve8that opens and closes the extension side main port (main port)6band is set to a higher valve opening pressure than the valve opening pressure of the leaf valve4. According to the damping valve V1configured as described above, it is possible to exert a suitable damping force with the leaf valve4when the shock absorber D extends and contracts at an extremely low speed, and to exert a large damping force with the main valve when the extension and contraction speed of the shock absorber D becomes high. Therefore, according to the damping valve V1of the present embodiment, it is possible to generate a damping force suitable for suppressing the extension and contraction of the shock absorber D in the shock absorber D according to the extension and contraction speed of the shock absorber D. In addition, in the damping valve V1of the present embodiment in which the piston (main partition wall body)6is fixed to the piston rod5and inserted into the cylinder (cylindrical body)1, the sub-piston2can move radially with respect to the piston rod5, and thus sliding resistance between the sub-piston2and the cylinder1does not increase even if there is a dimensional error in the piston6, the piston rod5, or the sub-piston2. Thus, according to the shock absorber D configured as described above, even if the structure in which the piston (main partition wall body)6and the sub-piston2are slidably in contact with the cylinder1is adopted, the sliding resistance does not increase and smooth extension and contraction is possible, so that high-level dimensional control is not required and thus the cost is also lowered. Note that when the main port allows bidirectional flow instead of one-way flow, the main valve may be configured as one valve, and in this case, the main valve may be a de Carbon valve, for example.

In addition, the shock absorber D of the present embodiment includes the cylinder1, the piston rod5inserted into the cylinder1, and the damping valve V1, wherein the cylinder1is a cylindrical body. According to the shock absorber D configured as described above, since the damping valve V1is provided, it is possible to exert a sufficient damping force and to obtain good damping force characteristics for suppressing the extension and contraction even when the shock absorber D extends and contracts at an extremely low speed.

In the damping valve V1of the above-described embodiment, the protrusion2eabutting on the outer circumference of the leaf valve4is provided on the outer circumferential side of the outer circumferential valve seat2cof the sub-piston2, and the protrusion2eis used as the aligning portion. However, as in a damping valve V2of one modification of the one embodiment illustrated inFIG.4, a protrusion21eprotruding axially from the inner circumferential side of a sub-piston21with respect to a port21dand abutting on the inner circumference of the leaf valve4may be provided, and the protrusion21emay be used as the aligning portion. In the description of the damping valve V2of the one modification, the same reference numerals are given to the same components as those of the damping valve V1of the one embodiment and the detailed description thereof is omitted in order to avoid duplication of description.

The sub-piston21as a partition wall body in the damping valve V2in the one modification is identical to the sub-piston2in the damping valve V1of the one embodiment in that the sub-piston21includes an annular main body21a, an annular outer circumferential valve seat21cprotruding axially from one end21bof the main body21athat is the axial upper end inFIG.3, a plurality of ports21dprovided side by side on the same circumference on the inner circumferential side of the outer circumferential valve seat21cin the main body21a, and a piston ring21fthat is mounted on an outer circumference of the main body21aand slidably in contact with the inner circumference of the cylinder1. On the other hand, the sub-piston21has a different configuration from that of the sub-piston2in that the sub-piston21includes a plurality of protrusions21eat equal intervals on the same circumference on the inner circumference of the one end21bof the main body21awith respect to the port21d, instead of including the protrusion on the outer circumferential side of the outer circumferential valve seat21c.

If the protrusion21eis ignored, an axial height of the one end21bof the main body21aincreases from the inner circumference toward the outer circumference, and an axial length of the main body21aon the inner circumferential side is slightly shorter than an axial length of the collar11.

As described above, the ports21dare arranged at equal intervals on the same circumference concentric with respect to the main body21a, and cause the intermediate chamber R3between the sub-piston2and the piston6to communicate with the extension side chamber R1through the main body21a.

The outer circumferential valve seat21cprotrudes axially to the upper side inFIG.2from the main body21aso as to surround an outer circumference of the port21d. In addition, when the sub-piston21is viewed from the upper side inFIG.4, the protrusion21ehas an arc-shaped cross section with a curved outer circumferential surface, and the outer circumferential surfaces of the protrusions21ehave the same curvature and are in contact with the same circle.

Furthermore, the protrusions21eare provided circumferentially at intervals so as not to radially overlap the port21d, considering that the flow path area of the port21dis not reduced when the protrusions21eare provided. That is, a part of the port21dis also formed between the protrusions21eand21ein the circumferential direction of the sub-piston21, but in particular, when there is no problem in securing the flow path area of the port21d, the part of the port21dmay not be provided between the protrusions21eand21e.

When the sub-piston21is loosely fitted to the collar11, a gap is formed between an inner circumference of the sub-piston21and the collar11, and thus the sub-piston21can be slightly displaced in the vertical direction inFIG.4, which is the axial direction. In addition, when the sub-piston21is inserted into the cylinder1, an outer circumference of the piston ring21fcomes slidably in contact with the inner circumference of the cylinder1, and the sub-piston21is loosely fitted to the collar11, and thus the sub-piston21is radially positioned only by the cylinder1.

As illustrated inFIG.4, the valve stopper31in the one modification includes a fitting portion31athat is annular and has a reduced inner diameter on the lower end side inFIG.4, a flange portion31bprotruding to an outer circumferential side from an end of the fitting portion31aprotruding to the upper side inFIG.4with respect to the protrusion21eof the sub-piston21and facing the upper end inFIG.4of the protrusion21ewith a gap, and an annular inner circumferential valve seat31cextending from an outer circumference of the flange portion31bto the sub-piston21side and arranged on an outer circumference of the protrusion21eto face the sub-piston21. An inner diameter of the fitting portion31aon the lower end side inFIG.2is set to be able to be fitted to the outer circumference of the small-diameter portion5aof the piston rod5, and the inner diameter of the fitting portion31aon the upper end side inFIG.4is larger than an outer diameter of the piston rod5on the upper side of the small-diameter portion5ainFIG.2. Thus, when the valve stopper31is fitted to the small-diameter portion5aof the piston rod5, the inner circumference of the fitting portion31aon the lower end side is fitted to the small-diameter portion5aof the piston rod5, and thus the valve stopper31is radially positioned with respect to the piston rod5, while the stepped portion at a boundary between the lower end and the upper end of the fitting portion31aabuts on the stepped portion5cof the piston rod5, and thus the valve stopper3is axially positioned with respect to the piston rod5.

In addition, when the sub-piston21is loosely fitted to the outer circumference of the collar11after the valve stopper31is installed to the piston rod5together with the spacer10and the collar11, the protrusion21eof the sub-piston21is accommodated in the annular gap formed between the fitting portion31aand the inner circumferential valve seat31c, and the inner circumferential valve seat31cfaces the inner circumferential side of the main body21aof the sub-piston21. The outer diameter of the inner circumferential valve seat31cof the valve stopper31is smaller than an inner diameter of the outer circumferential valve seat21c, and the outer circumferential valve seat21cis arranged at a higher position inFIG.4than the inner circumferential valve seat31c.

The inner diameter of the leaf valve4is set to be smaller than the outer diameter of the inner circumferential valve seat31cand to be in contact with an outer circumferential surface of each protrusion21eof the sub-piston21, and the outer diameter is set to be larger than the inner diameter of the outer circumferential valve seat2c. Thus, when the leaf valve4is placed on the sub-piston21, since the inner circumference of the leaf valve4abuts on each protrusion21eof the sub-piston21, the leaf valve4is aligned with respect to the outer circumferential valve seat21cof the sub-piston2by the protrusion21eand is radially positioned so as to be concentric with the outer circumferential valve seat21c. In this manner, the protrusion21efunctions as an aligning portion that aligns the leaf valve4with respect to the outer circumferential valve seat21c.

The protrusion21emay not have an arc shape as long as it can align the leaf valve4so as to be concentric with respect to the outer circumferential valve seat21c, but when the arc shape is used, the inner circumference of the leaf valve4easily slides on the outer circumferential surface of the protrusion21e, which can ensure smooth deflection of the inner circumference of the leaf valve4.

The leaf valve4is interposed between the inner circumferential valve seat31cand the outer circumferential valve seat21cin a state where the upper end inFIG.4of the inner circumference is seated on the inner circumferential valve seat31cand the lower end inFIG.4of the outer circumference is seated on the outer circumferential valve seat2c. Thus, similarly to the damping valve V1, the leaf valve4in the damping valve V2in the one modification functions as a de Carbon valve that is open to both the inside and the outside. Since the axial height of the main body21ain the sub-piston21decreases as it goes toward the inner circumference, a sufficient space such that the inner circumference of the leaf valve4can be deflected to the lower side inFIG.4is secured between the inner circumferential valve seat31cand the main body21aof the sub-piston21. In addition, since the protrusions21eare circumferentially provided at intervals, when the inner circumference of the leaf valve4is separated from the inner circumferential valve seat31c, the extension side chamber R1and the port21dcommunicate with each other through the gap between the protrusions21eand21e.

In addition, since the outer circumferential valve seat21cof the sub-piston21is arranged at a higher position inFIG.4than the inner circumferential valve seat31cof the valve stopper31, the leaf valve4is given an initial deflection when interposed between the inner circumferential valve seat31cand the outer circumferential valve seat21c, according to the difference in height between the inner circumferential valve seat31cand the outer circumferential valve seat21c. Since the leaf valve4is given the initial deflection in this manner, a valve opening pressure at which the leaf valve4is separated from the inner circumferential valve seat31cand the outer circumferential valve seat21cis set, and thus the valve opening pressure can be adjusted by adjusting the initial deflection amount. Note that, since the initial deflection amount given to the leaf valve4can be adjusted based on the difference in the axial distance between the inner circumferential valve seat31cand the outer circumferential valve seat21c, the valve opening pressure can be adjusted by adjusting the thickness of the annular plate of the spacer10and the number of stacked plates.

In the damping valve V2in the one modification, similarly to the damping valve V1, the main valve stopper12, the compression side main leaf valve7, the piston6, and the extension side main leaf valve8are provided on the lower side inFIG.4of the sub-piston21. Thus, the damping valve V2generates a damping force in the shock absorber D with the leaf valve4when the shock absorber D extends and contracts at an extremely low speed, with the orifices7aand8awhen the shock absorber D extends and contracts at a low speed, and with the compression side main leaf valve7or the extension side main leaf valve8when the shock absorber D extends and contracts at a high speed.

In addition, also in the damping valve V2in the one modification, the leaf valve4is aligned so as to be concentric with the outer circumferential valve seat21cof the sub-piston21radially positioned by the cylinder1, with the protrusion21efunctioning as the aligning portion of the sub-piston21. In this manner, since the leaf valve4is aligned so as to be concentric with the outer circumferential valve seat21c, in a state where the leaf valve4is seated on the outer circumferential valve seat2cand the inner circumferential valve seat3c, a gap is not formed between the outer circumference of the leaf valve4and the outer circumferential valve seat2c, and even if the annular leaf valve4becomes eccentric with respect to the inner circumferential valve seat3c, a gap that greatly affects the damping force is not formed between the inner circumference of the leaf valve4and the inner circumferential valve seat3c. From the above, the damping force characteristics when the shock absorber D including the damping valve V2performs the extension/contraction operation at an extremely low speed are, as illustrated inFIG.3, characteristics such that a damping force having a sufficient height to suppress the extension/contraction of the shock absorber D is exerted from the start of the movement of the shock absorber D. From the above, the shock absorber D is capable of exerting a sufficient damping force even when the shock absorber D extends and contracts at an extremely low speed, and obtaining good damping force characteristics for suppressing the extension and contraction when the shock absorber D extends and contracts at an extremely low speed.

As described above, the damping valve V2in the one modification of the present embodiment includes: the sub-piston (partition wall body)21that is annular, and is inserted into the cylinder (cylindrical body)1, is radially positioned only by the cylinder (cylindrical body)1, and has the annular outer circumferential valve seat21cprotruding axially from the axial one end21band the port21dprovided on the inner circumferential side of the outer circumferential valve seat21c; the valve stopper31having the annular inner circumferential valve seat31cfacing the one end21bof the sub-piston (partition wall body)21and having an outer diameter smaller than that of the outer circumferential valve seat21c; and the annular leaf valve4that is interposed between the outer circumferential valve seat21cand the inner circumferential valve seat31cand is set to be open to both the inside and the outside to open and close the port21d, wherein the sub-piston (partition wall body)21includes the protrusion (aligning portion)21ethat aligns the leaf valve4with respect to the outer circumferential valve seat21c.

In the damping valve V2configured as described above, since the leaf valve4is aligned with respect to the outer circumferential valve seat21cby the protrusion (aligning portion)21eprovided in the sub-piston21positioned only by the cylinder (cylindrical body)1, in a state where the leaf valve4is seated on the outer circumferential valve seat21cand the inner circumferential valve seat31c, a gap is not formed between the outer circumference of the leaf valve4and the outer circumferential valve seat2c, and a gap that affects the damping force is also not formed between the inner circumference of the leaf valve4and the inner circumferential valve seat31c. According to the damping valve V2of the present embodiment, it is possible to prevent the leakage of the hydraulic oil from the gap, and generate a sufficient damping force in the shock absorber D even when the flow rate of the hydraulic oil passing through the port21dis small. Therefore, according to the damping valve V2of the present embodiment, it is possible to obtain good damping force characteristics for suppressing the extension and contraction even when the shock absorber D extends and contracts at an extremely low speed.

In addition, in the damping valve V2of the present embodiment, the aligning portion provided in the sub-piston (partition wall body)2is a plurality of protrusions21ethat protrude axially at circumferential intervals from the inner circumferential side of the one end21bof the sub-piston (partition wall body)2with respect to the port21dand abuts on the inner circumference of the leaf valve4. In this manner, when the protrusion21eprovided on the inner circumferential side with respect to the port21dis used as the aligning portion, the outer diameter of the leaf valve4can be made smaller than the outer diameter of the outer circumferential valve seat21c, and thus the degree of freedom in designing the leaf valve4improves.

In the present embodiment, the damping valves V1and V2are mounted on the piston rod5, and the damping valves V1and V2are installed in the piston portion of the shock absorber D. However, in a case where the shock absorber D is a shock absorber having a reservoir chamber that stores liquid on the outer circumferential side of the cylinder1, a partition wall body or a partition wall body and a main partition wall body that define the compression side chamber R2and the reservoir may be provided at the end of the cylinder1, and the damping valves V1and V2may be installed between the compression side chamber R2and the reservoir chamber. That is, the damping valves V1and V2may be installed in the base valve portion of the shock absorber D. Furthermore, since the damping valves V1and V2may be installed at positions where a damping force can be generated when the shock absorber D extends and contracts, the installation positions of the damping valves V1and V2vary depending on the configuration of the shock absorber D, but the damping valves V1and V2may be installed at optimal positions depending on the configuration of the shock absorber D.

In addition, since the damping valves V1and V2can generate the damping force only with the leaf valve4without including the main partition wall body having the main port and the main valve that opens and closes the main port, it is a matter of course that the damping valves V1and V2including the partition wall body2(21), the valve stopper3(31), and the leaf valve4without including the main partition wall body and the main valve can be used in the shock absorber D.

The detailed description of preferred embodiments of the present invention has been made above, however, modifications, variations, and changes thereof can be made without departing from the scope of the claims.

REFERENCE SIGNS LIST