JPH02292538A - Variable damping force type hydraulic pressure shock absorber - Google Patents

Abstract

PURPOSE:To obtain a straight-line type damping force characteristic in an entire speed range by providing inner and outer side grooves double in at least one side liquid chamber side of a piston, and preparing a first communication passage for giving communication between one side of the inner side groove and the other side liquid chamber, and a second communication passage for giving communication between the outer side groove and the other side chamber. CONSTITUTION:An inner and outer side grooves 2h and 2j are provided double on the lower surface side of a piston 2, the groove 2h and an upper part liquid chamber A are communicated to each other with a first extension side communication passage 22, also the groove 2j and the liquid chamber A are communicated to each other with a second extension side communication passage, and an adjustment piece 15 is provided on the way as a variable orifice. As a result, a speed square characteristic by means of orifices 15a - 15d of the adjustment piece 15 and damping force of a speed 2/3 power characteristic by means of a first extension side disc valve 7 are obtained in series in a low speed range, and the speed 2/3 power characteristic is obtained is series in middle and high speed ranges. Consequently a straight-line type damping force characteristic can be obtained in an entire speed range.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a hydraulic shock absorber whose damping force characteristics can be varied and which is optimal for use in automobile suspensions.

(Prior Art) As a conventional variable damping force type hydraulic shock absorber, for example, one described in Japanese Utility Model Application Publication No. 164836/1983 is known.

In this conventional structure, as a means to generate damping force during the extension stroke, the piston has a first chamber that communicates with the upper liquid chamber and the lower liquid chamber.
A communication passage is bored and a disc valve is provided to open and close the communication hole, and a second communication passage is provided in the piston rod in parallel with the first communication passage to communicate the upper liquid chamber and the lower liquid chamber. A passage was formed, and a variable recess was provided in the middle of this second communication passage. A check valve was provided in the middle of the second communication path to make the flow state of the hydraulic fluid different between the extension stroke and the compression stroke.

According to this conventional pressure control valve, the first and second communication passages exist in parallel, and in the low piston speed range, the damping force characteristic of the speed squared due to the variable orifice of the second communication passage is On the other hand, in the medium and high piston speed range, the disc valve opens and a damping force characteristic of the speed 2/3 is obtained.

Furthermore, when the cross-sectional area of the flow passage is changed by the variable orifice, the slope of the damping force characteristic in the low piston speed range changes, and as the cross-sectional area of the flow passage is narrowed down, the damping force characteristic becomes in a high range.

(Problem to be Solved by the Invention) However, in such a conventional variable damping force hydraulic shock absorber, a communication passage is provided in parallel to the orifice hole of the piston as described above. In the low piston speed range, damping force is generated mainly due to the characteristics of the variable piston speed range, and in the medium and high piston speed ranges, the damping force is generated mainly due to the restriction created in the disc valve. The damping force characteristics are different depending on the speed range,
There was a problem in that it was not possible to obtain linear damping force characteristics over the entire speed range.

Furthermore, when a hydraulic shock absorber whose characteristics change depending on the speed range is applied to an automobile suspension, the characteristics of the suspension do not change consistently, resulting in very poor ride comfort and handling stability. 6 The present invention was developed by focusing on the problems of the prior art described above, and it is possible to obtain a linear damping force characteristic with a substantially constant rate of change in all speed ranges. The purpose of this invention is to provide a variable damping force type hydraulic shock absorber.

(Means for Solving the Problems) In order to achieve the above-mentioned objects, in the variable damping force type hydraulic shock absorber of the present invention, the inside is defined by a piston into upper and lower liquid chambers, which are filled with hydraulic fluid. an inner groove formed on the end surface of the piston on the side of at least one of the liquid chambers of the piston, the inner groove being at least partially arcuate and formed into two inner and outer grooves, each having a seat surface on its outer periphery; an outer groove, a disc valve provided in contact with both seat surfaces to open and close both grooves, a first communication passage that communicates the inner groove with the other liquid chamber across the piston, and a front outer groove. a second communication passage having a radial groove carved in the end face of the piston avoiding the inner groove to communicate the side groove with the other liquid chamber; and a variable diameter rifice provided in the middle of the second communication passage. has been established.

(Function) In the variable damping force type hydraulic shock absorber of the present invention, when the piston strokes from one liquid chamber side to the other liquid chamber side, in response to the change in the liquid pressure in the upper and lower liquid chambers, The hydraulic fluid flows into the outer groove via the first communication passage and the inner groove or the second communication passage, and further flexes the disc valve and flows from the outer groove through the gap between the disc valve and the outer seat surface. and flows into one liquid chamber.

That is, when the hydraulic fluid in the other fluid chamber flows into the outer groove, it flows through one of the following two paths. The first path flows into the inner groove from the first communication path,
From there, the fluid flows into the outer groove by deflecting the disc valve and passing between the inner seat surface of the outer periphery of the inner groove and the disc valve. In this case, a damping force having a speed ⅔ power characteristic is generated between the inner seat surface and the disc valve.

Further, the second path is a path where the liquid flows from the other liquid chamber through the second communication path and into the outer groove. A variable diameter orifice is provided in the middle of this second communication path, and a damping force having a square velocity characteristic is generated at this variable diameter orifice.

In this way, when the hydraulic fluid that has flowed into the outer groove via either of the two paths passes between the disc valve and the outer seat surface and flows into one of the fluid chambers, a damping force with a velocity 2/3 power characteristic is generated. occurs.

Therefore, when the piston speed is low, the hydraulic fluid flows into the outer groove via the second communication passage on the variable orifice side. Therefore, the damping force in the variable rift has a speed square characteristic whose rate of increase increases in response to an increase in speed, and the rate of increase decreases in response to an increase in speed between the outer seat surface and the disc valve. Since the damping force having the speed 2/3 characteristic is generated in series, it is possible to obtain a linear damping force characteristic.

Furthermore, when the piston speed increases and the flow resistance of the variable orifice increases beyond the closing force of the disc valve, the hydraulic fluid passes through the first communication passage and the inner groove to the disc valve without passing through the second communication passage. It flows between the valve and the inner seat surface and into the outer groove. Therefore, the damping force of the speed 2/3 power characteristic of the inner seat surface and the speed 2/3 power characteristic of the outer seat surface are applied in series. In this case as well, the speed 2/3 characteristic in which the rate of increase in damping force decreases as the piston speed increases is added in series, suppressing the decrease in the rate of increase in damping force, so it is still a straight line. damping force characteristics can be obtained.

Therefore, it is possible to obtain a damping force characteristic that is linear with respect to the piston speed in both the low speed range and the medium/high speed range.

Furthermore, when the flow rate of the variable recess is reduced, the damping force characteristic becomes a high range damping force characteristic, and when the flow rate is increased, the damping force characteristic becomes a low range damping force characteristic. In this case as well, this linear characteristic can be obtained over the entire damping force variable range.

(Example) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First, the configuration of the embodiment will be explained.

FIG. 1 is a sectional view showing the main parts of a variable damping force type hydraulic shock absorber according to a first embodiment of the present invention, and 1 in the figure indicates a cylindrical sill. This cylinder 1 is defined by a slidably mounted piston 2 into an upper liquid chamber A and a lower liquid chamber B, and both chambers A and B are filled with a hydraulic fluid such as oil.

The piston 2 is attached to the tip of a piston rod 3, that is, a retainer 4. Washer 5, pressure side disc valve 6. Piston 2, first expansion side disc valve 7. Second expansion side disc valve 8, washer 9. Spring seat 10. The springs 1l are installed one after another, and finally they are tightened with nuts l2.

More specifically, the piston 2 has a piston through hole 2a formed in the center thereof through which the piston rod 3 is inserted.

Further, on the upper end surface on the upper liquid chamber A side, a pressure side seat surface 2c is protruded at the same height as the boss portion 2b, and a pressure side groove 2d is formed inside the pressure side seat surface 2c. , and is communicated with the lower liquid chamber B through a pressure side communication passage 2l. Then, the compression side disc valve 6 comes into contact with the boss portion 2b and the compression side seat surface 2c. has been done.

Note that FIG. 2 is a sectional view taken along line II-II in FIG. 1 to show the top surface of the piston 2, and as shown in this figure,
The pressure side seat surface 2c and the pressure side groove 2d are provided at three locations, and the pressure side communication passage 2l that communicates the pressure side groove 2d with the lower liquid chamber B is formed to have a substantially rectangular cross section.

Further, as shown in FIG. 1, the pressure side disc valve 6
A gap serving as a communication passage 2e is formed between the upper surface of the piston 2 at a location other than the pressure side X2d, and this communication passage 2
A communicating groove 2f is formed on the upper surface of the piston 2 at the portion where e is formed, with one end opened to the piston through hole 2a, and an annular groove is formed at the end of the communicating groove 2f on the piston through hole 2a side. A groove 2g is formed (see FIG. 2).

On the other hand, on the lower end surface of the piston 2 on the lower liquid chamber B side, an inner groove 2h and an outer groove 2J are formed both inside and outside. As shown in FIG. 3, which is a cross-sectional view of FIG. It is formed. The inner groove 2h includes six first expansion side communication passages (first
One part of the liquid chamber A is communicated with the liquid chamber A by a communication passage 22.

Further, the outer groove 2j is communicated with the piston through hole 2a through a communication groove 2p formed in the radial direction avoiding the inner groove 2h, and an annular groove 29 is formed at the tip of the communication groove 2p.

As shown in FIG. It is closed by a first expansion side disk valve 7 and a second expansion side valve disk 8 which are provided in contact with 2n. The second expansion-side valve disc 8 has an outer circumferential portion formed to have an outer diameter that matches the inner seat surface 2m, and a biasing force of the spring 1l is applied to a position that matches the inner seat surface 2m. The valve closing force against the inner groove 2h is high.

Incidentally, the piston rod 3 has a hollow part 3a formed in the axial direction with the tip thereof opened on the lower liquid chamber side, and this hollow part 3a, an upper communication hole 3b bored in the radial direction, and a lower part. The communication hole 3C communicates with the annular part 2g and the annular part 29, respectively.

That is, the outer groove 2j formed on the lower surface of the piston 2 is connected to the communication groove 2p - the annular groove 2 as shown by the dashed line arrow.
q・~Lower communication hole 3C~Hollow part 3a~Upper communication hole 3b~
Upper liquid chamber A via annular groove 2g - communication groove 2f - communication path 2e
This path is called the second expansion side communication path R. Note that this second growth-side communication path R corresponds to the second communication path in the claims.

In the hollow part 3a in the middle of the expansion side communication path R, an adjuster l5 is provided so as to be rotatable coaxially with the piston rod 3, being held between the tenth side thrust push 16 and the lower side thrust push 17. .

This adjuster 15 constitutes a variable orifice in the claims, and is formed in a hollow cylindrical shape, and orifices 15a and 15b are bored so as to correspond to the upper communication hole 3b of the piston rod 3. and a lower orifice 15c. which corresponds to the lower communication hole 3c.
15d is drilled. In addition, both thrust push 16
．． 17 is formed into a hollow cylindrical shape.

Further, the first stage adjuster 15 is connected to an actuator (not shown) via a control rod 18, and based on the drive of the actuator, the respective orifices 15a to 15d are connected to both the communication holes 3b and 3b. 3c can be selectively matched.

Furthermore, the nut 12 is provided with a check valve l9. That is, the nut 12 has a through hole 12.
a is formed, and a valve body 19a is inserted into this through hole 12a.
are fitted. A disc valve 19b is biased by a spring 19c and is provided with respect to the valve body 19a so as to allow only the flow of hydraulic fluid from the lower liquid chamber B to the hollow portion 3a, and restrict the flow in the opposite direction. It is being

The configuration of the main parts of the first embodiment has been explained above based on FIGS. 1 to 3. A base is provided at the bottom of the cylinder of this embodiment (not shown), and this base has damping during the pressure stroke. A force generating valve is provided.

Next, the operation of the embodiment will be explained.

(B) During the extension stroke During the extension stroke of the piston 2, the hydraulic fluid in the upper fluid chamber A flows into the lower fluid chamber B as the fluid pressure in the upper fluid chamber A increases.
The path of the hydraulic fluid at this time is as follows.

In this embodiment, the hydraulic fluid in the upper fluid chamber A flows into the outer groove 2j following two paths, and from there, the first extension side disc valve 7 is bent, and the outer seat surface 2n and the hydraulic fluid flow into the outer groove 2j. It flows into the lower liquid chamber B through between the first expansion side disc valve 7 and the first expansion side disc valve 7.

Therefore, from the upper liquid chamber A to the outer groove 2j,
First, the first route is the communication path 2e.
From there, it flows into the inner groove 2h through the first growth-side communication passage 22, and from there, the first and second growth-side disc valves 7.8 are bent to connect the inner seat surface 2m and the first growth-side disc valve 7. This is a path that flows into the outer groove 2j through the gap created between them. In addition, another path is from the communication path 20 to the communication groove 2f.
Annular groove 2g - upper communication hole 3b - rift l5a, 15
b ~ Sai Rifisu 15c. 15d - Lower communication hole 3c - Annular ring 2q - This is the path leading to the communication groove 2p, that is, flowing into the outer groove 2j via the second expansion side communication path R.

As the hydraulic fluid flows through the above-mentioned path, a hydraulic pressure difference as shown in Fig. 4 is generated between the inner groove 2h and the outer groove 2j, and a damping force is generated. , between these full 2h and 2j, in the low piston speed range, the hydraulic fluid flows through the second extension side communication path R with less resistance, and the damping force characteristic is the square of the speed. In a high piston speed range, both disc valves 7.8 are opened at the position of the inner seat surface 2m to connect the inner groove 2h and the outer groove 2j, in response to the increase in flow resistance in the orifices 15a to 15d. Flow occurs in the path, resulting in a damping force characteristic of speed 2/3.

On the other hand, between the outer side 2j and the lower liquid chamber B, a difference in liquid pressure occurs as shown in Fig. 5, and a damping force is generated. 7
Due to the flow that opens the valve, the damping force characteristic of the speed 2/3 power, which is the characteristic of the first expansion side disc valve 7, is obtained.

Therefore, in the entire hydraulic shock absorber of the embodiment, during the extension stroke,
A characteristic is obtained in which the characteristics shown in FIGS. 4 and 5 are added in series, and this characteristic becomes a nearly linear characteristic as shown in FIG. 6.

The above-mentioned damping force characteristics can be obtained by rotating the adjuster 15 and adjusting the damping force characteristics between both communication holes 3b. Sai rifices 15a to 15d that correspond to 3c
You can change it by changing . That is, the fourth
~ In Figure 6, ■. ■ and ■ are the cases in which the smallest diameter of the rifts is matched to achieve high damping force characteristics. This shows a case in which the medium diameter is matched to give a medium damping force characteristic, and a case in which a maximum diameter is matched to give a low damping force characteristic.

(Port) During the pressure stroke During the pressure stroke of the piston 2, the working fluid in the lower liquid chamber B flows to the upper liquid chamber A in the piston 2 through two paths.

That is, the first route is to open the check valve 19 and reversely trace the second expansion side communication path R from the hollow portion 3a, that is, to follow the second expansion side communication path R from the hollow portion 3a. 15b, the upper communication hole 3b, the annular groove 2g, the communication groove 2f, and the communication path 2e, which flow into the upper liquid chamber A in this order. The other route is a route from the pressure side communication passage 21 to the upper liquid chamber A after opening the pressure side disc valve 6.

The hydraulic fluid flows through the one with less flow resistance out of these two paths, and normally when the piston speed is low, the check valve 19 is opened and the hydraulic fluid flows through the second expansion side communication path A.
In this case, a damping force having a velocity squared characteristic is generated.

In addition, in the middle and high speed ranges, the pressure side disc valve 6 is opened to allow the flow to flow, and in this case, a damping force having a speed ⅔ power characteristic is generated. Therefore, the damping force generated in the piston 2 during the pressure stroke has characteristics similar to those shown in FIG. 4, but the generated damping force itself is set lower than that.

Further, during this pressure stroke, a damping force having a speed 2/3 power characteristic is generated in the base valve (not shown), and this damping force is shown by a dotted line ■ in FIG.

Therefore, the characteristics of the combined damping force generated by the piston 2 and the base (not shown) are shown in FIG. As shown by ■ and ■, the characteristics are close to a straight line. Incidentally, the differences in the characteristics of (1) to (2) are caused by the selection of the refinement of the regulator 15.

As explained above, in the variable damping force hydraulic shock absorber according to the first embodiment of the present invention, the inner side groove 2h and the outer groove 2j are double provided on the lower surface side of the piston 2, and the inner side K2h and the upper liquid chamber A
are communicated with each other through the first extension side communication path 22, and the outer groove 2j
and the upper liquid chamber A are communicated through the second growth side communication path R, and the regulator 15 is provided as a variable, 1-IJ fist in the middle of the second growth side communication path R, so that the adjuster is not used in the low speed range. The damping force of the velocity squared characteristic by the orifices 15a to 15d of 15 and the velocity 2/3rd power characteristic by the first expansion side disc valve 7 can be obtained in series, and the velocity 2/3rd power characteristic can be obtained in series in the medium and high speed range. Because of this, it is possible to obtain linear damping force characteristics over the entire speed range.

Note that this characteristic applies to both communication holes 3b. The same effect can be obtained even if the aperture amount is changed by changing the orifice 15a to 15d that corresponds to the damping force, so that the effect that this linear characteristic can be obtained in the entire range of variable damping force can be obtained.

Furthermore, due to the characteristic that linear characteristics are obtained, the characteristics do not change suddenly depending on the piston speed, and when applied to automobile suspensions, it is possible to achieve both ride comfort and handling stability. can get.

In addition, in this embodiment, both expansion-side disc valves 7.8 for generating damping force during the extension stroke are provided on the lower surface side of the piston 2, and a compression-side disc valve 6 for generating damping force during the compression stroke is provided. Since the valve is provided on the upper surface of the piston 2, that is, the valve is provided on one side of the piston 2, the disc valves for the extension stroke and the compression stroke, the inner and outer grooves, and the communication passages are independently provided on both sides of the piston. This has the effect of simplifying the configuration, and at the same time, it is possible to set the damping force independently in the extension stroke and compression stroke, making it possible to set the damping force independently. A feature of increased freedom is obtained.

Next, a second embodiment shown in FIG. 8 will be described. still,
In describing the second embodiment, components similar to those in the first embodiment are given the same reference numerals as those in the first embodiment, and their explanations will be omitted.

This second embodiment differs from the first embodiment in the configuration of the second expansion side communication path 2R.

That is, as shown in FIG. 9, which is a sectional view taken along line IX in FIG. Not yet.

Moreover, the hollow part 2 3 of the piston rod 23 of the second embodiment
a is formed deeply upward to the position of the upper liquid chamber A, and the hollow portion 23a and the upper liquid chamber A communicate with each other through an upper communication hole 23b.

The adjuster 215 is also formed to have a longer dimension than the first embodiment, and has a recess 15a located at a position corresponding to the upper communication hole 23b. 15b is formed.

Therefore, the second expansion side communication path 2R is connected from the upper liquid chamber A to the upper communication hole 23b to the lower orifice 15a. 15b to the rifts 15c and 15d to the annular groove 29 and the communication groove 2p to reach the outer groove 2j.

Note that the functions and effects of this second embodiment are the same as those of the first embodiment, so the explanation will be omitted.

Next, a third embodiment shown in FIG. 11 will be described. In describing the third embodiment, the same components as in the 1.2 embodiment will be given the same reference numerals as in the 1.2 embodiment, and their explanation will be omitted.

In this third embodiment, the configuration of the second extension passage 2R is 1.2.
This is different from the example.

That is, the first cross-sectional view taken along the line XI[I-Xll1 in FIG.
As shown in FIG. 3, the annular ring 29 shown in the first and second embodiments is not formed on the lower surface of the piston 302 of the third embodiment, and the bottom surface of the piston 302 of the third embodiment is not formed with the annular ring 29 shown in the first and second embodiments. As shown in FIG. 12, an annular ring is formed on the upper surface of the piston 302. The annular ring 2g and the communication groove 2p on the lower surface of the piston are configured to communicate through a ring 28 formed in the axial direction on the inner circumference of the piston 302.

Moreover, the hollow part 33a of the piston rod 33 of the third embodiment
is formed deep upward to the position of the upper liquid chamber A,
The hollow portion 33a and the upper liquid chamber A communicate with each other through the upper communication hole 23b.

The adjuster 315 is formed with shorter dimensions than the second embodiment. That is, the piston mouth rod 33 and the adjuster 3
15 communicating holes 23c, 15c. 15d is provided at an axial position corresponding to the annular groove 2g of the piston 302.

Therefore, the second extension passage 2R extends from the upper liquid chamber to the upper communication hole 23b to the lower orifice 15a. 15b~year old Refice l
5 c. l 5 d-T' It becomes a route reaching the outer groove 2j via the A-shaped groove 2g, the groove 28, and the communication groove 2p.

Note that the operation and effect of this third embodiment are the same as those of the first and second embodiments, and the explanation thereof will be omitted.

Next, a variable damping force type hydraulic shock absorber according to a fourth embodiment shown in FIG. 14 will be explained. Incidentally, in describing this fourth embodiment, the same components as in each of the above-mentioned embodiments are given the same reference numerals, and the explanation thereof will be omitted.

This fourth embodiment is an example in which the adjuster 15 is made smaller and the number of open ends of the second communication path 4R toward the upper liquid chamber A side is increased.

That is, the piston rod 3 is provided with four communication holes 3b that communicate with the upper liquid chamber A and the hollow part 3a at positions that correspond to the respective rounded orifice holes formed in the adjuster. A communication hole 3c is formed that communicates an annular groove 2r formed on the inner periphery of the hollow portion 3a with the hollow portion 3a. Note that the annular groove 2r communicates with the communication groove 2p via another groove 28.

Therefore, between the upper liquid chamber A and the hollow part 3a, there are parallel orifice holes 15a. A hydraulic pressure difference is generated by 15b, 15c, and 15d, and a damping force is generated.

In particular, in the case of the fourth embodiment, compared to the first embodiment, the number of orifices through which the hydraulic fluid flows during the pressure stroke increases, so the number of setting elements for the damping force characteristics increases, and the degree of freedom in setting the characteristics increases. will improve. Furthermore, by making the adjuster 15 smaller, costs can be reduced.

Next, a variable damping force type hydraulic shock absorber according to a fifth embodiment shown in FIG. 15 will be explained. In explaining this fifth embodiment, the same components as in each of the above embodiments are given the same reference numerals, and the explanation thereof will be omitted.

This fifth embodiment is an example in which the piston rod 3 is divided into upper and lower halves into an upper rod 3l having an adjuster 15 and a lower rod 32 having the piston 2.

A large diameter 83 formed on the lower end surface of the upper rod 31
1a, the upper end of the lower rod 32 is fitted, and the union collar portion 21 formed on the lower rod 32 is fitted.
When the lower rod 32 is engaged with the union thread 3lb formed on the outer peripheral surface of the lower end of the upper rod 3I,
Both rods 31 and 32 are integrally connected by screwing together a union nut 33 provided in the rods 31 and 32.

According to this configuration, workability can be improved by separately assembling the adjuster 15 and the piston 2 to the upper rod 31 and lower rod 32, respectively.

Hereinafter, two embodiments of the present invention have been described in detail with reference to the drawings, but the specific configuration is not limited to these embodiments, and the present invention may be modified without departing from the gist of the present invention. Included in invention.

For example, in the example, the application was applied to a device that generates a damping force in the extension stroke, but it can of course be applied to a device that generates a damping force in the compression stroke, and furthermore, it can be applied to a device that generates a damping force in both the extension and compression strokes. You may use it whenever possible.

(Effects of the Invention) As explained above, in the variable damping force hydraulic shock absorber of the present invention, an inner groove and an outer groove are double provided on at least one side of the liquid chamber of the piston, and one of the inner grooves is provided with a double inner groove and an outer groove. By providing a first communication path that communicates with the other liquid chamber and a second communication path that communicates the outer groove with the other chamber, and further providing a variable orifice in the middle of the second communication path, low speed In the range, the damping force of the speed squared characteristic and the speed 2/3 power characteristic is obtained in series, and in the medium and high speed range, the speed 2/3 power characteristic is obtained in series, so the damping force is linear in the entire speed range. The effect is that the characteristics can be obtained. Note that this characteristic remains the same even when the aperture amount of the variable orifice is changed, so the effect that this linear characteristic can be obtained in the entire range of variable damping force can be obtained.

Furthermore, due to this linear characteristic, the characteristic does not change suddenly depending on the piston speed, and when applied to automobile suspensions, it is possible to achieve both ride comfort and handling stability. can get.

In addition, in the present invention, since both the inner and outer grooves and the disc valves are provided on one side of the piston, the disc valves, the inner and outer grooves, and the communication passages for the extension stroke and the compression stroke are provided independently on both sides of the piston. It can be easily provided, and this has the effect of simplifying the configuration.

[Brief explanation of drawings]

1 is a sectional view showing the main parts of a variable damping force type hydraulic shock absorber according to the first embodiment of the present invention, FIG. The figure is a sectional view taken along line III-III of FIG. 1 showing the lower surface of the piston, FIG. 4 is a graph showing the relationship between the hydraulic pressure difference between the inner groove and the outer side of the embodiment and the piston speed, and FIG. A graph showing the relationship between the hydraulic pressure difference between the outer groove and the lower liquid chamber and the piston speed, Fig. 6 is a graph showing the relationship between the damping force generated during the extension stroke of the embodiment and the piston speed, and Fig. 7. is a graph showing the relationship between the damping force generated during the pressure stroke and the piston speed in the first embodiment, and FIG. 8 is a sectional view showing the main parts of the variable damping force type hydraulic shock absorber according to the second embodiment of the present invention. Figure 9 is a cross-sectional view of Figure 8 LX-IX, Figure 10 is a cross-sectional view of Figure 8 x-x, Figures 11 to 1
3 is a sectional view corresponding to FIGS. 8 to 10 of a variable damping force hydraulic shock absorber according to a third embodiment of the present invention, and FIG. 14 is a variable damping force hydraulic shock absorber according to a fourth embodiment of the present invention. FIG. 15 is a sectional view showing the main parts of a variable damping force type hydraulic shock absorber according to the fifth embodiment of the present invention. A... Upper liquid chamber B... Lower liquid chamber l... Cylinder 2... - Piston 2h... Inner groove 2j... Outer groove 2m... Inner seat surface 2n... Outer seat surface 2[)...Communication groove (radial groove) 7...First extension side disc valve 8...Second extension side disc valve 15...Adjustor (variable rift) 15a...Orifice ( variable height refice) 15b...
・Rifice (variable orifice) 15c...Rifice (variable orifice) 15d...Rifice (variable orifice) 22...First extension side communication path (first communication path) 2
02...Piston

Claims (1)

[Scope of Claims] 1) A cylinder having an interior defined by a piston into upper and lower liquid chambers and filled with hydraulic fluid; an inner groove and an outer groove that are partially arcuate and formed double inside and outside, each having a seat surface on the outer periphery; a disc valve provided in contact with both seat surfaces to open and close both grooves; a first communication passage that communicates the inner groove with the other liquid chamber across the piston; and a radial direction carved on the end face of the piston avoiding the inner groove to communicate the outer groove with the other liquid chamber. the second with grooves
A variable damping force hydraulic shock absorber comprising: a communication passage; and a variable orifice provided in the middle of the second communication passage.