JP4048099B2 - Spring force adjustment structure of hydraulic shock absorber - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
This invention relates to a spring force adjusting structure of a hydraulic shock absorber, in particular, to an improvement of the spring force adjusting structure of a hydraulic shock absorber suitable for realization of the suspension system in the vehicle.
[0002]
[Prior art]
For example, some hydraulic shock absorbers constituting a suspension device in a vehicle include a spring force adjustment structure that enables adjustment to increase the spring force of a suspension spring as a spring interposed therein (for example, , See Patent Document 1).
[0003]
Then, the spring force adjusting structure has a jack mounted peripherally of the so-called cylinder constituting the damper body to a predetermined damping action during stretching operation in KaiSoshita the suspension spring, this jack the The movable end, which is the lower end of the suspension spring, is supported .
[0004]
Incidentally, the upper end of the suspension spring is engaged with the upper end of a so-called rod body is inserted so as to be retractable into the cylinder body of the constituting the buffer body with the cylinder body.
[0005]
On the other hand, the jack is extended by receiving hydraulic oil supplied from the inside of the shock absorber main body when the shock absorber main body is contracted, and the shock absorber main body is supplied with the supplied hydraulic oil when the shock absorber main body is extended. The contraction operation is performed by returning to the inside.
[0006]
In this case, jack, by the flow of the hydraulic oil flowing out of the buffer body, that is, depending on the contraction stroke of the shock absorber body, there is a set of its extension stroke is determined.
[0007]
Therefore, according to the spring force adjusting structure described above, it is possible to raise the lower end of the suspension spring by the extension operation of the jack during the contraction operation of the shock absorber body, and to increase the spring force in the suspension spring. By increasing the maximum absorption load in the shock absorber main body, it becomes possible to prevent bottoming in the vehicle.
[0008]
In addition, when the shock absorber body contracts with a large stroke, the jack extends with a large stroke, and the spring force in the spring is adjusted higher.
[0009]
[Patent Document 1]
Japanese Utility Model Publication No. 2-25307 (FIG. 1)
[0010]
[Problems to be solved by the invention]
However, in the spring force adjustment structure of the hydraulic shock absorber described above, the extension operation of the jack depends on the contraction operation of the shock absorber body, that is, the jack always extends when the shock absorber body contracts. There is.
[0011]
That is, it may be preferable not to increase the spring force of the suspension spring even if the shock absorber body is contracted, depending on the road surface on which the vehicle travels and the specifications of the vehicle.
[0012]
Nevertheless, the spring force adjusting structure of the hydraulic shock absorber described above is configured so that the jack extends depending on the shrinkage stroke of the shock absorber body, so that the shock absorber body can be contracted. In some cases, the spring force is always high even if it is small.
[0013]
As a result, even when a vehicle using a hydraulic shock absorber that embodies the above-described spring force adjustment structure as a suspension device travels on a good road and moves over a slight undulation on the road surface, the hydraulic shock absorber vessels also increases the spring force of the suspension spring is slightly contracted working slow, ride comfort loss of cracking in the vehicle.
[0014]
The present invention was devised in view of the above circumstances, and its object is to provide a spring force adjustment structure for a hydraulic shock absorber that does not increase the spring force under set conditions. is there.
[0015]
[Means for Solving the Problems]
To achieve the above object, the configuration of the spring force adjusting structure of a hydraulic shock absorber according to the present invention, a cylinder body comprising an outer tube which is disposed outside the cylinder with this cylinder, the retractable into the cylinder body and inserting the piston rod, contact with the jack having a sliding contact with the piston on the outer circumference of the outer cylinder is held on the outer periphery of the outer cylinder, the lower end with engaging the upper end to the upper end side of the piston rod to the piston in the jack a contact causes suspension spring, and a reservoir chamber defined between the cylinder and the outer cylinder, in the Haizai into the cylinder by a hydraulic shock absorber comprising a base valve portion for communicating the reservoir chamber into the cylinder , base valve of the reservoir chamber side become back side or base is Zaisa distribution behind the side serving as the reservoir chamber side of the sliding member which is housed within the valve unit the base valve portion Other has a biasing member for biasing in a direction toward the sliding member to the piston rod in the cylinder, when the shrinkage rate in the hydraulic shock absorber is greater than the speed region set, said base valve unit or sliding member and formed by supplying the jack hydraulic oil in the cylinder to retract in a direction toward the reservoir chamber against the urging force of the above-mentioned biasing member.
[0016]
Therefore, according to this configuration, to over speed range contraction speed of the hydraulic shock absorber is set, the supply of hydraulic fluid to the jack is not realized, therefore, the spring force of the spring is maintained as is The
[0017]
On the other hand, when the contraction speed exceeds the set speed range, hydraulic oil is supplied to the jack. At this time, the piston in the jack slides to move the lower end of the suspension spring. Therefore, the spring force in the suspension spring is adjusted to either high or low.
[0018]
In the above configuration , the valve seat member that constitutes the base valve portion is retracted in the direction toward the reservoir chamber against the urging force of the urging member disposed on the back side that is the reservoir chamber side , or , the sliding member is slidable in housed disk member to the valve seat in the member constituting the base valve portion.
[0019]
Further, biasing member comprises a rubber tubular member or coil spring, further hydraulic fluid becomes excessive supply to the jack, perforated in the hole in the outer cylinder to be opened in a sliding of the piston constituting the jack It is opened to the reservoir chamber defined between the outer cylinder and the cylinder via the.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, based on the illustrated embodiments is a description of the invention, the spring force adjusting structure of a hydraulic shock absorber of the present invention is basically as shown in FIGS. 1 and 2, a cylinder 1 this a cylinder body C formed of the outer cylinder 2 which was disposed outside the cylinder 1, a piston rod inserted through the retractably into the cylinder body C (not shown), it is held on the outer periphery of the outer tube 2 the outer A jack J provided with a piston 4 slidably in contact with the outer periphery of the cylinder 2, a suspension spring S whose upper end is locked to the upper end side of the piston rod and whose lower end is brought into contact with the piston 4 in the jack J ; a reservoir chamber R which is defined between the cylinder 2, is Haizai into the cylinder 1 and becomes a base valve unit 3 for communicating the reservoir chamber R into the cylinder 1.
[0021]
Then, the spring force adjusting structure of the hydraulic shock absorber, rear side serving as a reservoir chamber R side of the sliding member which is accommodated behind side or the base valve portion 3 serving as a reservoir chamber R side of the base valve portion 3 made and a biasing member made of a distribution Zaisa been in rubber cylindrical body 34 like that energize the base valve portion 3 or the sliding member in a direction serving the forward direction toward the piston rod in the cylinder 1 to the .
[0022]
And also, in the spring force adjusting structure of the hydraulic shock absorber, the piston rod is in the time of contraction of the hydraulic shock absorber entering the cylinder 1, when exceeding the speed area in which the shrinkage rate is set, the formed by supplying hydraulic fluid in the cylinder 1 the jack J retracted in a direction toward the reservoir chamber base valve unit 3 or the sliding member against the biasing force of the biasing member.
[0023]
Below, describing in detail, Figure 1 shows a hydraulic shock absorber embodying the spring force adjusting structure according to the present invention, the hydraulic shock absorber, constitutes the suspension device in a vehicle, whereas members serving piston rod while being connected to the vehicle body side in the vehicle (not shown), also it is the other member while forming the hydraulic shock absorber, the cylinder body C for inserting the retractably said piston rod is connected to the axle side of the vehicle (not shown) The
[0024]
The spring S, which is a suspension spring disposed between the piston rod and the cylinder body C, is not shown in the figure, but the other end is the other end while the upper end as one end is locked to the upper end side of the piston rod in a fixed state. The lower end, that is, the movable end referred to in the present invention is brought into contact with the jack J.
[0025]
The cylinder body C is formed in a multi-cylinder structure having a cylinder 1 which is an inner cylinder in the shaft core portion and an outer cylinder 2 outside the cylinder 1 as shown in each drawing of FIG.
[0026]
The jack J is held on the outer periphery from the bottom end of the outer cylinder 2 to the vicinity thereof, that is, on the outer periphery of the bottom end portion 2a (see FIG. 2).
[0027]
At this time, as shown in FIG. 2, a space between the cylinder 1 and the outer cylinder 2 is set as a reservoir chamber R, and this reservoir chamber R is placed inside a bottom end portion of the cylinder 1 via a base valve portion 3 disposed. The cylinder 1 communicates with the cylinder 1.
[0028]
Further, the above-described piston rod is inserted into the cylinder 1 so as to be able to protrude and retract, and an unillustrated piston is continuously provided at the tip of the piston rod so as to be slidable within the cylinder 1.
[0029]
At this time, the piston defines a rod-side oil chamber (not shown) and a piston-side oil chamber R1 (not shown) in the cylinder 1, and the rod-side oil chamber and the piston-side oil chamber R1 are not shown in the figure. It is possible to communicate with each other through an attenuation portion.
[0030]
Incidentally, an arbitrary structure may be adopted for the structure for generating the damping force in the damping part disposed in the piston. In the base valve part 3, the center rod is connected to the valve seat member 31 as shown in the figure. The damping valve 33, which is fixed to the free end of the outer peripheral end by fixing the inner peripheral end under the distribution of 32, allows the hydraulic oil to be sucked into the cylinder 1 from the reservoir chamber R, and the hydraulic oil in the cylinder 1 is stored in the reservoir 1 A so-called compression side damping force is generated when flowing into the chamber R.
[0031]
By the way, the above description of the base valve portion 3 is disclosed as an existing base valve portion called a base valve portion. In the present invention, the base valve portion 3 is configured as follows. ing.
[0032]
In other words, in the present invention, the base valve portion 3 is provided with a biasing member disposed behind the reservoir chamber R which is the lower side in the drawing, that is, in the illustrated case, a rubber cylindrical body 34. Is urged in the forward direction, which is the direction toward the inside of the cylinder in the figure.
[0033]
When the contraction speed in the hydraulic shock absorber exceeds the set speed region, the rubber cylindrical body 34 as the urging member is hydraulically actuated by the hydraulic oil from the piston-side oil chamber R1 in the cylinder 1. by, but is through the base valve unit 3 to retract, as shown in FIG. 3, are ulcers.
[0034]
At this time, the partition wall portion 31a is hung down to an appropriate length downward from the lower end surface of the valve seat member 31 so that the hydraulic oil in the cylinder 1 cannot flow into the reservoir chamber R via the damping valve 33. There seated on the bottom 6a of the collar member 6 described later serving other members.
[0035]
Incidentally, the provision of the partition wall 31a controls the lowering stroke of the valve seat member 31 so that the rubber cylindrical body 34 is not crushed more than necessary when the valve seat member 31 is crushed. This is advantageous in that it can be done.
[0036]
Incidentally, a spring force adjusting structure of a hydraulic shock absorber according to the present invention, becomes a jack J described above, the following describes this spring force adjusting structure.
[0037]
In addition, about the code | symbol C which shows a cylinder body, and the code | symbol J which shows a jack, the indication is abbreviate | omitted in each figure after FIG.
[0038]
First, as shown in FIG. 1 and FIG. 2, the jack J has a piston 4 that supports a movable end that is the lower end in the drawing of the spring S that is a suspension spring. The bottom end of the bottom member 5 that constitutes the jack J is configured such that the upper end side that is the side is in sliding contact with the outer periphery of the outer cylinder 2 under the arrangement of the bearing 41, and the lower end side that is the lower side in FIG. It is in sliding contact with the outer periphery.
[0039]
At this time, as for the bottom member 5, as shown in the figure, it is formed in a bottomed cylindrical shape, and the female screw portion 5b formed on the inner periphery of the cylindrical portion 5a is connected to the vicinity thereof from the lower end of the outer cylinder 2. The outer end of the outer cylinder 2 is held by being screwed into a male screw 2b formed on the outer periphery of the bottom end 2a (see FIG. 2).
[0040]
In this spring force adjustment structure, a pressure chamber R2 is defined between the fixed-side bottom member 5 and the movable-side piston 4, and the pressure chamber R2 is opened in the outer cylinder 2. It communicates with the inside of the outer cylinder 2 through the hole 2c.
[0041]
Therefore, in this spring force adjusting structure, the hydraulic oil is supplied to the pressure chamber R2 to expand the pressure chamber R2 (see FIG. 3), thereby causing the piston 4 to slide. It is possible to raise the movable end, which is the lower end of the spring S supported by.
[0042]
On the other hand, the inner side of the outer cylinder 2 in which the pressure chamber R2 communicates with the hole 2c has the following structure.
[0043]
First, as shown in FIGS. 2 and 3, a collar member 6 is provided adjacent to the inner periphery of the bottom end 2a of the outer cylinder 2, and the cylinder 1 is connected to the collar member 6 while being centered. Yes.
[0044]
The collar member 6 is formed in a bottomed cylindrical shape, and the bottom portion 6a closes the bottom end of the cylinder 1 while sitting on the bottom portion 5c of the bottom member 5 described above, and a hole 6b opened in the center portion. Is communicated with the base valve portion 3 described above.
[0045]
At this time, the collar member 6, have a land portion 6c serving as a reduced diameter portion projecting to the inner peripheral side of the lower end, the cylinder 1 and the inner side of the land portion 6c to plugging the lower end of the cylinder 1 Centering.
[0046]
The land portion 6c has a cutout portion 6d that allows communication between the lower side of the base valve portion 3 and the reservoir chamber R side.
[0047]
On the other hand, in the collar member 6, a groove 6 e extending in the radial direction while communicating with the hole 6 b opened at the center is formed on the back surface of the bottom portion 6 a in the figure, which is the lower surface. On the outer periphery of the cylindrical portion 6f adjacent to the inner periphery of the bottom end portion 2a of the cylinder 2, there is formed a groove 6g that communicates with the groove 6e and extends in the vertical direction in the figure, which is the axial direction of the collar member 6. Has been.
[0048]
The flow path formed by the hole 6b, the groove 6e, and the groove 6g enables communication between the lower portion of the base valve portion 3 and the pressure chamber R2 through the hole 2c that is opened in the outer cylinder 2. To do.
[0049]
Therefore, when the collar member 6 formed as described above is provided, the hydraulic oil from the piston side oil chamber R1 in the cylinder 1 is attenuated by the base valve portion 3 as indicated by an arrow in FIG. It flows out below the base valve portion 3 through the valve 33 and can flow into the reservoir chamber R through the inside of the notch portion 6d and the cylindrical portion 6f of the collar member 6.
[0050]
Then, as indicated by an arrow in FIG. 3, the hydraulic oil from the piston side oil chamber R <b> 1 in the cylinder 1 passes through the hole 32 a in the shaft core portion of the center rod 32 in the base valve portion 3 through this base valve. While flowing out below the portion 3, it can flow into the pressure chamber R2 in the jack through the hole 6b, the grooves 6e, 6f in the collar member 6 and the hole 2c opened in the cylinder 1.
[0051]
2 shows an operating state when the contraction speed in the hydraulic shock absorber is in a set speed region. At this time, the hydraulic oil moves faster than the set value. Therefore, the hydraulic oil in the piston-side oil chamber R1 in the cylinder 1 can easily pass through the damping valve 33 of the base valve portion 3.
[0052]
As a result, the working oil from the piston side oil chamber R1 in the cylinder 1 flows out to the reservoir chamber R through the damping valve 33 in the base valve unit 3, this time, the predetermined compression side damping force is generated .
[0053]
In contrast, the method shown in Figure 3, shows the operating state when the shrinkage rate in the hydraulic shock absorber is greater than the speed region set, at this time, the movement of hydraulic oil in comparison to the setpoint faster Therefore, the hydraulic oil in the piston side oil chamber R1 in the cylinder 1 cannot easily pass through the damping valve 33 of the base valve portion 3.
[0054]
Therefore , the valve seat member 31 constituting the base valve portion 3 moves down inside the lower end of the cylinder 1 against the cylindrical body 34 made of rubber by the hydraulic action due to the differential pressure between the upper and lower sides of the base valve portion 3. The partition wall 31 a of the valve seat member 31 is seated on the bottom 6 a of the collar member 6.
[0055]
As a result, the flow of hydraulic oil from the piston-side oil chamber R1 to the reservoir chamber R is restricted, and the amount of hydraulic oil flowing from the piston-side oil chamber R1 into the pressure chamber R2 through the hole 32a of the center rod 32 increases. For this reason , the piston 4 is raised by the internal pressure in the pressure chamber R2, and the suspension spring S is compressed by the amount of the piston 4 raised, and the spring force is increased.
[0056]
From the above, in the spring force adjusting structure of the hydraulic shock absorber according to the present invention, when the contraction speed in the hydraulic shock absorber exceeds the set speed region, the supply of the hydraulic oil to the jack J is realized. is adjusted to a spring force in the suspension spring S is increased.
[0057]
However, if the spring force of the suspension spring S is increased more than necessary, the ride comfort in the vehicle is impaired, and the mechanical structure of the jack J causes the piston 4 to stroke more than necessary. Lack of rationality.
[0058]
Therefore, in the present invention, suppose drained hydraulic oil supplied to the pressure chamber R2 in the jack J from the pressure chamber R2 to the reservoir chamber R, specifically, as shown in FIG. 4, operation of the pressure chamber R2 Oil is allowed to flow into the reservoir chamber R through a hole 2d opened in the outer cylinder 2.
[0059]
Although the configuration to be solved by the present invention is basically satisfied by the configuration as described above, it is possible to take the following considerations.
[0060]
FIG. 5 shows a modification of the base valve portion 3 and the surrounding structure as compared with the above-described configuration. Specifically, the base valve portion 3 has a partition wall in the valve seat member 31. The formation of the portion 31a (see FIGS. 2 and 3) is omitted.
[0061]
In the cylinder 1, the lower end is seated on the bottom 6 a of the collar member 6, while the hole 1 a facing the notch 6 d formed in the land portion 6 c of the collar member 6 is opened at the lower end. .
[0062]
Therefore, according to this embodiment, when the valve seat member 31 in the base valve portion 3 is lowered by the hydraulic action in the cylinder 1, the hole 1 a is closed by the valve seat member 31.
[0063]
As a result, this embodiment is advantageous in that a conventional valve seat member in which the partition wall portion 31a is not formed as the valve seat member 31 can be used as it is.
[0064]
Next, what is shown in FIG. 6 is a modification of the structure of the base valve portion 3. Specifically, the base valve portion 3 is located at a considerably higher position in the cylinder 1 than in the embodiment described above. Is distributed.
[0065]
And the partition part 31a in the valve seat member 31 is supposed to be formed so as to hang longer than in the above-described embodiment.
[0066]
Incidentally, at the lower end portion of the cylinder 1, a stepped portion (not shown) that regulates the most elevated position of the valve seat member 31 is set at a higher position than in the above-described embodiment. Yes.
[0067]
And, for the biasing member biasing the rear side of the valve seat member 31 described above, instead of the rubber cylindrical body 34 in the described embodiment, it consists of a coil spring 35.
[0068]
Therefore, according to this embodiment, it is more advantageous in that long-term durability can be obtained as compared with the case where the urging member is made of a rubber cylindrical body 34.
[0069]
FIG. 7 shows that the base valve portion 3 itself is disposed in a fixed state in the lower end portion of the cylinder 1 and does not slide, while the lower end of the valve seat member 31 constituting the base valve portion 3 is shown. The disk member 36, which is a sliding member slidably mounted on the side , is lifted by a coil spring 37, which is an urging member disposed on the back side that is the reservoir chamber R side , that is, a direction toward the inside of the cylinder body 1. It is energized in the forward direction.
[0070]
At this time, the lower end of the valve seat member 31 is seated on the bottom portion 6a of the lower collar member 6, and the lower end is provided with a notch portion 6d formed in the land portion 6c of the collar member 6 provided adjacent to the outer periphery thereof. Opposing notches 31b are formed.
[0071]
The disk member 36 is, as it were is Haizai the free piston manner to divide the lower base valve unit 3 up and down, have a cylindrical portion 36a which downwardly depending on the lower surface of the central portion, of the cylindrical portion 36a and sets a path 36b having an effect squeezing the inner, lower end of the cylindrical portion 36a that is seated on the bottom 6a of the collar member 6, its falling is prevented.
[0072]
Therefore, in the case of this embodiment manages the diameter of the passage 36b in the disk member 36, by controlling the spring force of the coil spring 37, hydraulic oil flows into either of the reservoir chamber R or the pressure chamber R2 that obtained to set the Kano timing easily.
[0073]
In the above description, the case where the spring force adjusting structure according to the present invention is embodied in the hydraulic shock absorber constituting the suspension device in the vehicle has been described as an example. but, for example, it is one that is utilized in the apparatus such, can be expected the same effect as was described above.
[0074]
【The invention's effect】
As described above, in the invention of each claim, the supply of hydraulic oil to the jack is not realized until the contraction speed of the hydraulic shock absorber exceeds the set speed region, and accordingly, the spring in the suspension spring is not realized. Power is maintained as it is.
[0075]
On the other hand, when the contraction speed exceeds the set speed range, hydraulic oil is supplied to the jack, and at this time, the piston in the jack slides to move the movable end of the spring. The spring force of the suspension spring is adjusted to either high or low.
[0076]
More specifically, in the invention of each claim, the hydraulic shock absorber constitutes a suspension device in the vehicle, while the contraction speed when the piston rod enters the cylinder due to road surface vibration or the like is set. When the region is exceeded, the hydraulic oil in the cylinder is supplied to the jack, the jack is extended, the movable end of the suspension spring is moved, and the spring force of the suspension spring is adjusted to be high.
[0077]
Therefore, for example, when the vehicle gets over a large road surface protrusion at high speed, the spring force becomes high, and it becomes possible to avoid bottoming in the vehicle, and when the vehicle gets over a gentle road surface protrusion. Therefore, it is possible to avoid the inconvenience that the spring force becomes unnecessarily high and the ride comfort is impaired.
[0078]
As a result, according to the present invention, adjustment for increasing the spring force is not realized under the set conditions, and is optimal for use in, for example, a hydraulic shock absorber constituting a suspension device in a vehicle.
[Brief description of the drawings]
FIG. 1 is a front view of a hydraulic shock absorber according to an embodiment of the present invention, partially broken away.
FIG. 2 is a partial longitudinal sectional view showing a part of the portion shown in FIG. 1 in an enlarged manner.
3 is a view showing the operating state from the place shown in FIG. 2 in the same manner as FIG.
4 is a view similar to FIG. 3 showing a further operating state from what is shown in FIG. 3;
FIG. 5 is a partially enlarged longitudinal sectional view showing another embodiment.
FIG. 6 is a view showing another embodiment in the same manner as FIG.
FIG. 7 is a view showing another embodiment in the same manner as FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Cylinder 2 Outer cylinder 2a Bottom end part 2b Male thread part 2c, 6b, 32a Hole 3 Base valve part 4 Piston 5 Bottom member 5a, 6f Cylindrical part 5b Female thread part 5c, 6a Bottom part 6 Color member 6c Land part 6d Notch part 6e, 6g Groove 31 Valve seat member 31a Bulkhead portion 32 Center rod 33 Damping valve 34 Rubber cylindrical body 35, 57 Coil spring 36 Disc member 36a Cylindrical portion 36b Passage 41c Bearing C Cylinder body as the other member J Jack R Reservoir chamber R1 Piston side oil chamber R2 Pressure chamber S Spring as suspension spring

Claims (5)

A cylinder body comprising an outer tube which is disposed outside the cylinder with this cylinder, a piston rod inserted through the retractably into the cylinder body, the sliding contact piston is held on the outer periphery of the outer cylinder on the outer periphery of the outer cylinder A jack provided, a suspension spring for locking the upper end to the upper end side of the piston rod and the lower end abutting against the piston in the jack, a reservoir chamber defined between the cylinder and the outer cylinder, is Haizai in the hydraulic shock absorber comprising a base valve portion for communicating the reservoir chamber into the cylinder, a sliding member that is housed behind the side or the base valve portion serving as a reservoir chamber side of the base valve portion has been Zaisa distribution behind the side serving as the reservoir chamber side biasing member for biasing the base valve unit or sliding member in a direction towards the piston rod in the cylinder, When shrinkage rate in the pressure shock absorber exceeds the speed range that is set, the cylinder above the base valve unit or the sliding member is retracted in the direction toward the reservoir chamber against the urging force of the above biasing member spring force adjusting structure of a hydraulic oil hydraulic shock absorber characterized by comprising supplying the jack 2. The hydraulic shock absorber according to claim 1, wherein the valve seat member constituting the base valve portion is retracted in the direction toward the reservoir chamber against the urging force of the urging member disposed on the rear side which is the reservoir chamber side . Spring force adjustment structure   2. The spring force adjusting structure for a hydraulic shock absorber according to claim 1, wherein the sliding member is a disc member slidably accommodated in a valve seat member constituting the base valve portion. The spring force adjusting structure for a hydraulic shock absorber according to claim 1 or 2, wherein the urging member comprises a rubber cylindrical body or a coil spring. Claim hydraulic oil becomes over-supply to the jack, which are open to the reservoir chamber through the holes in the perforated in the outer cylinder to be opened in a sliding of the piston constituting the jack 1, claim 2 or claim 3 The spring force adjustment structure of the hydraulic shock absorber as described in

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