JP2517796Y2 - Hydraulic shock absorber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a hydraulic shock absorber suitable for use in a vehicle suspension.

(Prior Art) As a conventional hydraulic shock absorber, for example, West German Patent 833574
Issue number is known.

In this conventional hydraulic shock absorber, a piston that defines an upper fluid chamber and a lower fluid chamber of a cylinder is provided with a communication hole that communicates the upper fluid chamber and the lower fluid chamber, and the outer periphery of the communication hole. An inner seat surface is formed on the inner seat surface, and an outer seat surface is formed at an outer peripheral position of the inner seat surface so as to project to the lower liquid chamber side from the inner seat surface, and contact the inner and outer seat surfaces respectively to form the first disc valve. The second disc valve and the second disc valve are both fastened to the piston, and an intermediate chamber is formed between the disc valves.

Therefore, during the extension stroke, the hydraulic fluid in the upper liquid chamber opens the first disc valve from the communication hole to flow into the intermediate chamber, and further opens the second disc valve to flow into the lower liquid chamber. A damping force is generated between the first disc valve and the inner seat surface, and a damping force is generated between the second disc valve and the outer seat surface.

(Problems to be Solved by the Invention) However, in the conventional hydraulic shock absorber as described above, the inner seat surface and the outer seat surface are formed in two steps on the end surface of one piston. Therefore, the inner seat surface and the first disc valve have to be smaller in diameter than the outer seat surface and the second disc valve. Therefore, the rigidity of the first disc valve tends to be high and the damping force can be reduced. It's difficult.

On the contrary, the outer seat surface and the second disc valve must be larger in diameter than the inner seat surface and the first disc valve, and therefore the piston tends to have a large diameter and the hydraulic shock absorber becomes large. It is difficult to make it compact.

That is, when the damping force is reduced, the diameter of the piston becomes large, and when the piston is made compact, the damping force becomes high, and there is a problem that it is difficult to make the damping force and the compact size compatible.

Further, in the conventional hydraulic shock absorber, the first and second disc valves are fastened together with the pistons by the nuts so that the relative positional relationship with respect to the pistons changes simultaneously. If the plate thickness is changed to change the rigidity, the position of the second disc valve with respect to the piston also changes. Therefore, a means for preventing the relative position of the second disc valve with respect to the piston from changing is required, and there is a problem that the degree of freedom in setting rigidity is low.

Further, depending on the piston portion, the damping force characteristic cannot be made variable.

The present invention has been made by paying attention to the above-mentioned conventional problems, and linear characteristics can be obtained in all speed ranges, and it is easy to achieve compactness, and at the extension side and the compression side. It is an object of the present invention to provide a damping force variable hydraulic shock absorber in which damping characteristics can be set separately and the degree of freedom in setting damping characteristics is high.

(Means for Solving the Problems) In order to achieve the above-mentioned object, in the hydraulic shock absorber of the present invention, a lower liquid chamber that is expanded in an extension stroke and a pressure in a cylinder filled with hydraulic fluid. A piston provided so as to be slidable by partitioning the liquid chamber into an upper liquid chamber that is expanded in the stroke, a piston-side recess formed annularly on the lower liquid chamber side of the piston, and a side facing the piston. An expansion side recess is formed in the expansion side recess, and a peripheral wall of the expansion side recess is fitted to an annular wall formed on the inner periphery of the piston side recess to form an intermediate chamber between the piston and the expansion side body; A pressure side communication hole formed in the piston to communicate the upper liquid chamber and the lower liquid chamber at a position outside the annular wall of the side recess, and the pressure side communication hole can be opened only toward the upper liquid chamber. The provided damping side damping valve and the damping side damping valve are A pressure-side bypass passage provided with a pressure-side check valve that allows the upper and lower liquid chambers to communicate with each other by passing, and allows the flow from the lower liquid chamber only in the direction of the upper liquid chamber, and is provided in the middle of this pressure-side bypass passage. A pressure-side variable orifice that throttles the flow rate of the hydraulic fluid from the lower liquid chamber to the upper liquid chamber, a first extension-side communication hole formed in the piston to connect the upper liquid chamber and the intermediate chamber,
A second extension-side communication hole formed in the extension-side body to communicate the intermediate chamber and the lower liquid chamber, and a first extension-side communication hole formed on the outer periphery of the first extension-side communication hole at the intermediate chamber-side end surface of the piston. The extending side seat surface and the second extending side seat surface formed on the outer periphery of the second extending side communication hole at the lower liquid chamber side end surface of the extending side body, and the first extending side communication hole facing the intermediate chamber. The first damping-side disc valve, which is provided in a state of contact with the first stretching-side seat surface so as to be able to open only, and the second stretching-side communication hole, can be opened only toward the lower liquid chamber. The second damping side disk valve, which is provided in a state of contact with the second stretching side seat surface, has a high damping, and the intermediate chamber and the lower liquid chamber downstream of the first spreading side disk valve bypass the second stretching side disk valve. And the extension side bypass passage that communicates with each other and is provided in the middle of this extension side bypass passage, and It provided with the extension side variable orifice for throttling the flow of hydraulic fluid to the liquid chamber.

(Operation) In the hydraulic shock absorber of the present invention, when the working fluid is circulated from the upper fluid chamber to the lower fluid chamber in the stroke, the following flow paths are followed.

That is, the hydraulic fluid in the upper liquid chamber flows into the intermediate chamber by opening the first extension side disc valve from the first extension side communication hole of the piston. Then, in the state where the expansion side variable orifice is open, in the low speed range where the second expansion side disk valve does not open, it flows from the intermediate chamber to the lower liquid chamber via only the expansion side bypass passage, while In the medium / high speed range where the expansion side disk valve opens, the second expansion side disk valve opens mainly through the second expansion side communication hole of the expansion side body and flows into the lower liquid chamber.

Therefore, first, when the hydraulic fluid flows through the gap formed between the first expansion side disc valve and the first seat surface, a low damping force of the speed 2/3 power characteristic is generated, and further, in the low speed range. ,
When the hydraulic fluid flows through the expansion side variable orifice provided in the middle of the expansion side bypass passage, a damping force having a velocity squared characteristic is generated, and thus the speed 2/3 of the first expansion side disc valve is generated.
In contrast to the squared characteristic (the change rate decreases as the speed increases), the speed squared characteristic (the change rate increases as the speed increases) due to the expansion side variable orifice, which is symmetrical to this speed 2/3 squared characteristic. By being added in series, the damping force rises well in the low speed range, and a sharp rise is suppressed, and linear characteristics are obtained. On the other hand, in the middle and high speed ranges, the second expansion side disc valve and Since a gap is formed between the two seat surfaces, a high damping force with a velocity 2/3 power characteristic is generated mainly when flowing through the gap, and the influence of the expansion side variable orifice and the first expansion side disk valve Becomes smaller, a linear characteristic due to the velocity 2/3 power characteristic of the second expansion side disc valve is obtained, and therefore a linear characteristic is obtained in the entire velocity range.

Whether or not the working fluid flows from the intermediate chamber through the second extension side communication hole to open the second extension side disk valve and to flow is determined by the flow rate of the extension side variable orifice. That is, as the flow rate of the expansion side variable orifice increases, the flow resistance of the expansion side variable orifice increases and the hydraulic pressure in the intermediate chamber rises, and as a result, the second expansion side disk valve opens. Therefore, the larger the opening area of the expansion side variable orifice, the second
The opening timing of the expansion side disc valve is delayed to have a low damping characteristic. On the other hand, the smaller the opening area of the expansion side variable orifice is, the earlier the opening timing of the second expansion side disc valve is to have a high damping characteristic.

Further, in the present invention, since the first expansion side seat surface is formed on the piston and the second expansion side seat surface is formed on the expansion side body, the outer diameters of both expansion side seat surfaces are set independently. be able to. Therefore, the diameters of both expansion-side disc valves can be set independently of each other not only for the compression-side damping valve but also for the first and second expansion-side disc valves. The pressure receiving area can be set independently, and the damping force characteristic of each disk valve can be set independently. further,
Even if the plate thickness of the first expansion-side disk valve is changed, the relative position of the second expansion-side disk valve with respect to the expansion-side body does not change.

Further, since the intermediate chamber in which the first expansion side disc valve is arranged is formed by fitting the peripheral wall of the expansion side recess of the expansion side body to the annular wall of the inner circumference of the piston side recess, a small number of parts of two members With the number of points, it is possible to form an intermediate chamber having excellent liquid-tightness without facing the sliding portion with the cylinder.

Embodiment An embodiment of the present invention will be described in detail below with reference to the drawings.

 First, the configuration of the embodiment will be described.

FIG. 1 is a sectional view showing an essential part of a hydraulic shock absorber according to one embodiment of the present invention, in which 1 denotes a cylindrical cylinder. This cylinder 1 is defined by a slidably mounted piston 2 into an upper liquid chamber A whose volume is reduced during the extension stroke and a lower liquid chamber B whose volume is reduced during the pressure stroke. Is filled with hydraulic fluid.

The piston 2 is fastened by a nut 6 together with a compression side body 4 and an extension side body 5 to a mounting portion 3a formed at the tip of a piston rod 3 with a small diameter. That is, the stopper plate 7, washer 8, pressure side check valve 9, pressure side body 4, washer 10, pressure side disc valve (pressure side damping valve) 11, piston 2, first extension side disc valve 12, washer 13 with respect to the mounting portion 3a. Then, the extension side body 5, the second extension side disc valve 14, the washer 15, the spring seat 16 and the spring 17 are sequentially mounted, and finally the nut 6 is tightened.

Further, in detail, the pressure side body 4 has a groove portion 4a formed on the upper surface thereof and a first portion on the outer periphery thereof.
The pressure side seat surface 4b is formed. And this groove 4a
Is a pressure side communication groove 4c formed on the upper surface of the pressure side body 4, an annular groove 4d formed on the inner circumference of the pressure side body 4, an upper communication hole 3b formed in the mounting portion 3a, and the inside of the mounting portion 3a. It is communicated with the lower liquid chamber B through the hollow portion 3c formed in.

The pressure side check valve 9 is provided in contact with the first pressure side seat surface 4b. The pressure side check valve 9 opens and closes the groove portion 4a with respect to the upper liquid chamber A, and the stopper plate 7 restricts the bending more than a predetermined amount when the valve is opened.

Next, the piston 2 has a pressure side groove 2a formed on its upper surface (see FIG. 2) and an annular first extension side groove 2b formed on its lower surface (see FIG. 3). 2 is a plan view of the piston 2 and FIG. 3 is a bottom view of the piston 2.

The pressure side groove 2a communicates with the lower liquid chamber B through the pressure side communication hole 2c, and the first extension side groove 2b communicates with the upper liquid chamber A through the first extension side communication hole 2d.

Further, the first pressure side seat surface 2e is formed on the outer periphery of the pressure side groove 2a.
Is formed, and the pressure side disc valve 11 is provided in contact with the first pressure side seat surface 2e. The pressure side disc valve 11 is restricted from being bent more than a predetermined amount when it is opened by the lower surface of the pressure side body 4.
The pressure side disc valve 11 is the pressure side check valve 9
The one with higher rigidity is used.

Also, on the outer periphery of the first stretch side groove 2b, the first stretch side seat surface
2f is formed, and the first expansion side disc valve 12 is provided in contact with the first expansion side seat surface 2f. still,
The first extension-side seat surface 2f is restricted from bending by a predetermined amount or more by the upper surface of the extension-side body 5.

Furthermore, on the lower surface of the piston 2, an annular piston-side recessed portion 2g that is recessed upward is formed on the outer periphery of the first extension side seat surface 2f. On the other hand, on the upper surface of the extension side body 5, an extension side concave portion 5a is formed by being depressed downward,
As shown in the figure, the inner peripheral annular wall of the piston side recess 2g
2j with the peripheral wall of the extension side recess 5a fitted, the piston 2
The extension side body 5 is provided on the lower surface of the.

Then, a washer is provided between the piston 2 and the extension side body 5.
13 is interposed and the upper surface of the extension side body 5 (the extension side recess
An intermediate chamber 18 is formed between the lower surface of the piston 2 and the upper surface of the extension side body 5 by the groove portion 5b (see FIG. 4) formed in the bottom surface 5a). An annular second extension side groove 5c is formed on the lower surface (see FIG. 5), and a second extension side groove 5c communicates with the groove portion 5b.
An extension side communication hole 5d is provided. Incidentally, FIG. 4 is a plan view of the extension side body 5, and FIG. 5 is a bottom view of the extension side body.

Then, the second expansion side disc valve is formed on the second expansion side seat surface 5e (FIG. 5) formed on the outer periphery of the second expansion side groove 5c.
14 are provided in abutment. That is, the second expansion-side disc valve 14 has the second expansion-side groove 5c (second expansion-side communication hole 5d).
Is opened and closed with respect to the lower liquid chamber B. The second expansion side seat surface 5e is formed to have a diameter slightly larger than that of the first expansion side seat surface 2f.
It has a slightly larger diameter than the expansion side disk valve 12 and has high rigidity. The spring seat 16 is in contact with the lower surface of the outer circumference of the second expansion-side disk valve 14, and the urging force of the spring 17 is applied to the outer circumference of the second expansion-side disk valve 14.

Further, on the upper surface of the extension side body 5, there is formed an extension side communication groove 5g for communicating the annular groove 5f formed in the inner circumference of the extension side body 5 with the groove portion 5b. 5f
Is the lower communication hole 3d formed in the mounting portion 3a and the hollow portion 3c.
And is communicated with the lower liquid chamber B via. That is, the extension side communication groove 5g, the annular groove 5f, the lower communication hole 3d, and the hollow portion 3c form the extension side bypass passage III in the claims.

In addition, a hollow adjuster 20 is rotatably housed in the hollow portion 3c while being supported by an upper thrust bush 21 and a lower thrust bush 22 in the vertical direction. This adjuster 20
At a position corresponding to the upper communication hole 3b and the lower communication hole 3d,
A pressure side variable orifice 20a and an expansion side variable orifice 20b are formed, respectively, and based on the rotation of the adjuster 20, the upper communication hole 3b and the lower communication hole 3d are connected to the lower liquid chamber B or are in a blocked state. It can be changed. The rotation of the adjuster 20 is performed by the control rod 23 connected to the actuator (not shown).

 Next, the operation of the embodiment will be described.

(A) During pressure stroke When the piston 2 strokes downward in the drawing, the hydraulic fluid in the lower liquid chamber B moves to the upper liquid chamber A. At that time, there are two paths through which the hydraulic fluid can flow.

The first path is a pressure side bypass passage indicated by I in the figure, passing from the lower liquid chamber B into the hollow portion 3c of the mounting portion 3a, from the pressure side variable orifice 20a to the upper communication hole 3b, the annular groove 4d and the pressure side. This is a path for flowing into the groove 4a through the communication groove 4c, opening the pressure side check valve 9 from there, and flowing into the upper liquid chamber A. The second path is the pressure side main path indicated by II in the figure and passes through the pressure side communication hole 2c of the piston 2 and the pressure side groove 2a.
Is a path through which the pressure side disk valve 11 is opened to flow into the upper liquid chamber A.

That is, when the pressure side variable orifice 20a and the upper communication hole 3b are aligned as shown in FIG. 1, the low damping force characteristic shown in FIG. 6 is obtained. A damping force having a velocity squared characteristic is generated in the pressure side bypass passage I through the pressure side variable orifice 20a, and the pressure side check valve 9 and the first pressure side seat surface 2e are connected in series with the damping force.
A damping force having a velocity 2/3 power characteristic is generated between and.

Then, in the medium / high speed operation range, the hydraulic pressure difference between the upper liquid chamber A and the lower liquid chamber B becomes large, and the pressure side disc valve 11
Will open and flow through the pressure side main path II. At this time, a damping force having a velocity 2/3 power characteristic is generated between the pressure side disc valve 11 and the second pressure side seat surface 2e.

On the other hand, in the case of using the high damping force characteristic, the adjuster 20 is rotated to shift the position of the pressure side variable orifice 20a with respect to the upper communication hole 3b, and the pressure side bypass passage I is blocked.

In this case, during the stroke of the piston 2, the working fluid is circulated only in the pressure side main passage II, and the high damping force characteristic as shown in FIG. 6 is obtained.

(B) During Stroke When the piston 2 strokes upward in the figure, the hydraulic fluid in the upper liquid chamber A moves to the lower liquid chamber B. That is, the hydraulic fluid in the upper liquid chamber A first flows into the first extension side groove 2b through the first extension side communication hole 2d, and from there, the first extension side disc valve 12
Is opened and flows into the intermediate chamber 18.

Then, as a flow path from the intermediate chamber 18 to the lower liquid chamber B, there are two paths, that is, an extension side bypass passage III and an extension side main passage IV.

That is, the extension side bypass passage III is a path that passes through the extension side communication groove 5g, the annular groove 5f, the lower communication hole 3d, and the hollow portion 3c.
In addition, the extension-side main passage IV extends from the second extension-side communication hole 5d to the second extension-side communication hole 5d.
It flows into the expansion side groove 5c, and from there, the second expansion side disc valve 14
Is a path to the lower liquid chamber B by opening the valve.

Then, as shown in FIG. 1, when the lower communication hole 3d and the expansion side orifice 20b are matched to each other so that the expansion side bypass passage III is in the communication state, the low damping force characteristic as shown in FIG. In this case, when operating at low speed, the hydraulic fluid flows through the extension side bypass passage III, and a damping force having a velocity 2/3 power characteristic is generated between the first extension side disk valve 12 and the first extension side seat surface 2f, and in series with it. The expansion-side orifice 20b causes a damping force of the velocity squared characteristic, which is a characteristic that the rate of change decreases as the velocity increases (2/3 power characteristic), and conversely a characteristic that the rate of change increases (squared characteristic). ) Is a symmetrical characteristic with, while improving the rising of the damping force in the low speed range,
Suppressing the subsequent sharp rise, a nearly linear damping force characteristic can be obtained.

Further, at the time of medium / high speed operation, the fluid pressure in the intermediate chamber 18 increases due to the flow resistance of the extension side bypass passage III, and the second extension side disk valve 14 opens so that the working fluid flows through the extension side main passage IV. Become. In this case, the influence of the expansion-side orifice 20b and the first expansion-side disk valve 12 is reduced, and a linear characteristic due to the speed 2/3 power characteristic of the second expansion-side disk valve 14 is obtained.

On the other hand, in the case of using the high damping force characteristic, the adjuster 20 is rotated to shift the position of the expansion side orifice 20b, and the expansion side bypass passage III is blocked. In this case, even in the low speed region, the air flows through the extension side main passage IV, and the characteristics shown in FIG. 6 are obtained.

As described above, in the hydraulic shock absorber of the embodiment, the damping force characteristic is set to the low damping force characteristic and the high damping force in all the operating ranges from the low speed region to the medium / high speed region in both the pressure stroke and the extension stroke. It has the feature that it can be clearly different from the characteristics. Therefore, when this hydraulic shock absorber is used in a vehicle suspension, be sure to properly use it, such as low damping force characteristics to improve riding comfort and high damping force characteristics to improve steering stability. The feature that can be obtained is obtained.

Further, in this embodiment, the piston 2 and the extension side body 5 are fitted to each other so as to form an intermediate chamber 18 between the two and 5,
Since the first expansion-side seat surface 2f is formed on the piston 2 and the second expansion-side seat surface 5e is formed on the expansion-side body 5, the outer diameters of both seat surfaces 2f and 5e are the compression side valves 9 and 11. Can be set independently of each other (it is preferable to form the diameter smaller than that on the pressure side to set the damping force higher), and it is possible to set them independently of each other. Therefore, the diameters of the first expansion-side disk valve 12 and the second expansion-side disk valve 14 can be set independently, and the first and second expansion-side disk valves 14 can be set independently.
The pressure-receiving areas of the expansion-side disk valves 12 and 14 are also characterized in that they can be set independently as desired.

Furthermore, due to this feature, the second expansion side disc valve
In contrast to 14, it is easier to increase the outer diameter of the first expansion-side disk valve 12 to lower the rigidity of the first expansion-side disk valve 12 and achieve low damping, and conversely,
The outer diameter of the second expansion-side disk valve 14 is smaller than that of the first expansion-side disk valve 12, so that the piston 2 and the hydraulic shock absorber can be easily made compact. Therefore, it has a feature that both low damping force and compactness can be achieved. Moreover, in this embodiment, the piston side recess 2g formed on the lower surface of the piston 2
The expansion side recess 5a formed on the upper surface of the expansion side body 5 in the annular wall 2j of
Since the intermediate chamber 18 is formed by fitting the peripheral walls of the above, the number of parts is as small as two members of the piston 2 and the extension side body 5,
It is characterized in that the intermediate chamber 18 excellent in liquid tightness can be formed without facing the sliding portion with the cylinder 1.

Furthermore, when the plate thickness is changed to change the rigidity of the first extension side disc valve 12, the fitting state of the extension side body 5 with respect to the piston 2 only changes (the fitting margin of both changes). As a result, the relative positions of the extension side body 5 and the second extension side disc valve 14 change at the same time with respect to the piston 2, and the extension side body 5 and the second extension side disc valve 14
The relative position does not change with respect to 14, and it is not necessary to change the thickness of the washer 13. Therefore, it is easy to change the valve rigidity by changing the plate thickness,
High degree of freedom in setting.

The embodiment of the present invention has been described in detail above with reference to the drawings.
The specific configuration of the present invention is not limited to this embodiment, and even if there is a design change or the like within the scope of the present invention, it is included in the present invention.

For example, in the embodiment, in order to change the damping force characteristic, the upper communication hole and the lower communication hole are blocked by the adjuster at the time of the high damping force characteristic, but it is not completely blocked as described above. A small-diameter orifice hole may be aligned with both communication holes.

Further, a constant orifice may be formed on the surface of the second seat so that the working fluid flows through the constant orifice in the extremely low speed operation region.

(Effect of the Invention) As described above, in the hydraulic shock absorber of the present invention,
A structure in which a first expansion side seat surface is formed on a piston, a second expansion side seat surface is formed on an expansion side body, and a first expansion side disk valve and a second expansion side disk valve are provided in contact with each seat surface. Therefore, the outer diameters of the first and second expansion-side seat surfaces can be independently set, and the first and second expansion-side disc valve diameters can be independently set. Therefore, it is possible to increase the diameter of the first expansion-side disk valve to achieve low damping, and to reduce the diameter of the second expansion-side valve to reduce the size of the valve body. At the same time as the effect is obtained, the pressure receiving areas of the first and second extension side disc valves can be arbitrarily set independently, and the degree of freedom in setting the damping force characteristic is increased.

Furthermore, since the relative position of the second expansion-side disk valve with respect to the sub-valve body does not change even if the plate thickness of the first expansion-side disk valve is changed, the mounting position and rigidity of the first and second expansion-side valves can be freely set. The effect of improving the degree is obtained.

Further, in the present invention, an annular piston-side recess is formed on the lower liquid chamber side of the piston, and the peripheral wall of the extension-side recess of the extension-side body is fitted into the annular wall of the inner periphery of the piston-side recess to form the piston. Since the intermediate chamber is formed between the extension side body and two members, it is possible to form an intermediate chamber excellent in liquid tightness without facing the sliding portion with the cylinder. To be

In addition, the damping force characteristic can be changed by the compression side / extension side variable orifice, and the damping force variable type hydraulic shock absorber having the above effect can be provided. Moreover, in the damping force characteristic during the extension stroke, even when the damping force characteristic is low, it does not depend only on the extension side variable orifice, but also on the characteristic of the first extension side disk valve. The velocity 2/3 power characteristic and the velocity 2 power characteristic can be obtained in series to obtain a nearly linear damping force characteristic, and the damping force characteristic can be changed by this linear damping force characteristic. The effect that the damping force characteristics can be clearly changed is obtained not only at low speeds with low flow rates but also at medium / high speed operations with high hydraulic fluid flow rates.

[Brief description of drawings]

FIG. 1 is a sectional view showing a hydraulic shock absorber according to an embodiment of the present invention, FIG. 2 is a plan view of a piston of the embodiment, FIG. 3 is a bottom view of the piston of the embodiment, and FIG. FIG. 5 is a plan view of the extension side body, FIG. 5 is a bottom view of the extension side body of the example, and FIG. 6 is a graph showing damping force characteristics of the example hydraulic shock absorber. A ... Upper liquid chamber B ... Lower liquid chamber 1 ... Cylinder 2 ... Piston 2c ... Pressure side communication hole 2d ... First extension side communication hole 2f ... First extension side seat surface 2g ... Piston side recess 2j ... Annular wall 5 ... Extension side Body 5a ... Recess on the extension side 5d ... Communication hole on the second extension 5e ... Seat surface on the second extension 9 ... Check valve 11 on the compression side ... Damping valve on the compression side 12 ... Disk valve on the first expansion 14 ... Disk valve on the second expansion 18 ... Intermediate chamber 20 ... Regulator 20a ... Compression side variable orifice 20b ... Expansion side variable orifice I ... Compression side bypass passage III ... Expansion side bypass passage

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) References Microfilm (JP, U) A microfilm (JP, U) of the contents of the specification and drawings attached to the application for Japanese Patent Application No. Sho 61-133841 (No. Sho 63-40642)

Claims (1)

(57) [Scope of utility model registration request] 1. A cylinder, which is filled with hydraulic fluid, is slidably provided by partitioning a liquid chamber into a lower liquid chamber expanded in a stroke and an upper liquid chamber expanded in a pressure stroke. A piston, a piston side recess formed annularly on the lower liquid chamber side of the piston, and an extension side recess on the side facing the piston, and a peripheral wall of the extension side recess on the inner circumference of the piston side recess. An extension side body that is fitted to the formed annular wall to form an intermediate chamber between the piston and the piston, and connects the upper liquid chamber and the lower liquid chamber at a position outside the annular wall of the piston side recess. A pressure side communication hole formed in the piston, a pressure side damping valve provided so that the pressure side communication hole can be opened only toward the upper liquid chamber, and an upper liquid chamber and a lower liquid chamber bypassing the pressure side damping valve. And communicate only with the lower liquid chamber to the upper liquid chamber. A pressure-side bypass passage provided with a pressure-side check valve that allows communication, a pressure-side variable orifice that is provided in the middle of this pressure-side bypass passage to restrict the flow rate of the working fluid from the lower fluid chamber to the upper fluid chamber, and the upper fluid chamber. A first extension side communication hole formed in the piston by communicating with the middle chamber and a second extension side communication hole formed in the body by connecting the middle chamber and the lower liquid chamber; A first extension side seat surface formed on the outer periphery of the first extension side communication hole on the intermediate chamber side end surface of the piston, and formed on the outer periphery of the second extension side communication hole on the lower liquid chamber side end surface of the extension side body. The second expansion side seat surface and the low damping first expansion side disc valve provided in contact with the first expansion side seat surface such that the first expansion side communication hole can be opened only toward the intermediate chamber. And the second extension side communication hole can be opened only toward the lower liquid chamber. 2 second high attenuation provided extension phase seat surface in abutment
An expansion-side disc valve, an expansion-side bypass passage that communicates the intermediate chamber and the lower liquid chamber downstream of the first expansion-side disc valve by bypassing the second expansion-side disc valve, and in the middle of the expansion-side bypass passage. A hydraulic shock absorber, comprising: an expansion-side variable orifice that is provided and that restricts the flow rate of the hydraulic fluid from the intermediate chamber to the lower fluid chamber.