JPH0314935A - Damping force control system for hydraulic shock absorber - Google Patents

Abstract

PURPOSE:To obtain a damping force characteristic linearly changing in response to respective piston speeds by providing variable orifices in connecting passage from an open window formed against one of two disc valves arranged in series on one end face side of a piston to other chamber. CONSTITUTION:During the expansion stroke with which a piston 2 reduces the volume of a liquid chamber A, operating liquid flows into a lower chamber B together with liquid pressure rise in the liquid chamber A. When the piston speed is low, a damping force characteristic proportional to the square of the speed due to constant sectional area of constant orifices 7i, 9g and variable orifices 15b, 15c, and a damping force characteristic proportional to the 2/3 power of the speed due to variable sectional area of a second expansion side disc valve 10, are obtained simultaneously. Thus, characteristic in which the rate of change is nearly constant can be obtained. When the piston speed is high, both expansion side disc valves 8, 10 are opened to obtain a damping force characteristic in which characteristics proportional to the 2/3 power of the speed are added in series. For the damping characteristic proportional to the 2/3 power of the speed, the rate of change in damping force is small, and nearly constant rate of change can be obtained. In the compression stroke, linear characteristic can also be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a system for controlling the damping force of a hydraulic shock absorber.

(Prior Art) As a conventional damping force control system for a hydraulic shock absorber, for example, one described in Japanese Utility Model Application Publication No. 61-164836 is known.

In this conventional structure, as a means for generating damping force during the extension stroke, a communication hole is bored in the piston to communicate the upper liquid chamber and the lower liquid chamber, and a disc valve is provided to open and close this communication hole. In addition, a bypass passage is formed in the piston rod in parallel with the communication hole to communicate the upper liquid chamber and the lower liquid chamber. An orifice was provided, and by rotating this variable orifice with a motor, the cross-sectional area of the bypass passage could be changed.

Therefore, in a low piston speed range, the disc valve remains closed, the hydraulic fluid flows through the bypass path, and a damping force having a square speed characteristic is generated.

On the other hand, in the middle and high piston speed ranges, the flow rate of the hydraulic fluid increases, the disc valve is opened, a flow rate is generated in the communication hole, and the disc valve generates a damping force with speed 2/3 power characteristics.

Also, if you want to increase the generated damping force, narrow the variable orifice. In this case, the damping force in the low piston speed range becomes high, and accordingly, the opening timing of the disc valve becomes earlier, and the damping force in the middle and high piston speed ranges also becomes high.

If you want to lower the generated damping force, open the variable orifice. In this case, the damping force in the low piston speed range becomes high, and the opening timing of the disc valve is accordingly delayed, resulting in a decrease in the damping force in the medium and high piston speed ranges. (Problem to be Solved by the Invention) However, in the conventional damping force control system of the hydraulic shock absorber described above, since the bypass passage was provided in parallel with the communication hole, The damping force characteristics differ depending on the speed range (in the low piston speed range, the speed squared characteristic due to the variable orifice, and in the medium and high piston speed ranges, the speed 2/3rd power characteristic due to the disc valve), resulting in a linear damping force characteristic. Therefore, there was a problem in that it was not possible to achieve both steering stability and ride comfort.

The present invention was developed by focusing on the above-mentioned conventional problems, and it is possible to obtain a linear damping force characteristic with respect to piston speed, thereby achieving both steering stability and ride comfort in all ranges. The present invention aims to provide a damping force control system for a hydraulic shock absorber.

(Means for Solving the Problems) In order to achieve the above-mentioned object, in the damping force control system for a hydraulic shock absorber of the present invention, a cylinder filled with hydraulic fluid is divided into one fluid chamber and the other fluid chamber. a piston provided to define a liquid chamber; a first disc valve and a second disc valve arranged in series on one end surface side of the piston;
At least six of the two disc valves are provided in the middle of a communication path that communicates an opening window formed on one end surface of the piston with the other liquid chamber to be opened and closed by one of the disc valves. A variable orifice and an aperture control means for controlling the amount of aperture of the variable orifice are provided.

Further, in the invention according to claim 2, the piston is a first piston formed with a first seat surface that abuts the first valve, and a second piston that forms a second seat surface that abuts the second valve. It was formed with.

(Function) The operation of the damping force control system for a hydraulic shock absorber of the present invention will be explained.

When the other fluid chamber rises, the working fluid in the other fluid chamber flows through the communication path and into the open window through the variable orifice, and then opens the disc valve and flows into the one fluid chamber.

Therefore, the damping force characteristic of the speed squared due to the variable orifice and the damping force characteristic of the speed 2/3rd power characteristic due to the disc bulge can be obtained simultaneously in series.In other words, the rate of change in the low piston speed range is small, and the A speed squared characteristic with a large rate of change in the speed range and, symmetrically, a speed 273rd power characteristic with a large rate of change in the low piston speed range and a small rate of change in the middle and high piston speed ranges are obtained in series. Therefore, a damping force with linear characteristics can be obtained.

In addition, by adjusting the throttle amount of the variable orifice using the throttle control means, the opening pressure of the disc valve on the side where this opening window is provided is changed, and the damping force range is varied from the low damping force range to the high damping force range. It can be changed, and when the throttle amount of the variable orifice is reduced, the damping force characteristic becomes high, and when the throttle amount is increased, the damping force characteristic becomes low.

Therefore, in the present invention, linear damping force characteristics can be obtained in all ranges from low to high damping ranges.

Furthermore, in the present invention, the opening pressure of the disc valve can also be adjusted by adjusting the area of the opening window. (Example) Hereinafter, an example 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 hydraulic shock absorber according to an embodiment of the present invention to which the damping force control system of the present invention is applied, and 1 in the figure is a cylindrical shape. This shows the cylinder. This cylinder 1 is divided into an upper liquid chamber (one liquid chamber) A and a lower liquid chamber (the other liquid chamber) B by a slidably loaded piston 2, and there is an oil or other fluid inside. It is filled with liquid.

The piston 2 has a retainer 4 at the tip of the piston rod 3. Washer 5a. Pressure side disc valve6. 1st piston body7. 1st expansion side disc valve 8. washer 5b
．． Second piston body9. 2nd extension side disc valve 10
．． It is constructed by sequentially installing washers 5C and tightening them with nuts l3. More specifically, in the first piston body 7, a pressure side communication hole 7a is bored in the axial direction near the outer periphery to communicate the upper liquid chamber A and the lower liquid chamber B. This pressure communication hole 7a is connected to a second
As shown in Fig. 3 and Fig. 3 showing the lower surface of the first piston body 7, there are provided at four locations, and an overwhelming seat surface 7b protrudes around the opening end on the upper liquid chamber 8 side of each pressure side communication hole 7a. At the same time, a boss portion 7C is provided on the inner upper surface of the first piston body 7 and has the same height as the pressure side seat surface 7b. As shown in FIG. 1, the overwhelming disc valve 6 is provided in contact with the pressure side seat surface 7b. Further, on the lower surface of the first piston body 7, a deep annular opening 7d is formed along the position of the overwhelming communication hole 7a, and an annular opening window 7e is formed at a position inside of the opening 7d. (See Figure 3). The opening window 7e is communicated with the upper liquid chamber A through four first communication holes 7f, which are small holes, and a passageway 7g formed between the first piston body 7 and the pressure side disc valve 6.

Further, the outer periphery of the opening window 7e is provided with a l-th extension side seat surface (a first
A sheet surface) 7h is formed, and this first extension side sheet surface 7h
Four first constant orifices 71 are formed in (see FIG. 3).

Note that a boss portion 7j is provided inside the opening Z7e.

A first expansion side disc valve 8 is provided in contact with the first expansion side seat surface 7h. The second piston body 9 is provided with an annular wall 9a on the outer periphery of its upper surface, and
A boss portion 9b is provided on the inner periphery of the top surface. Then, the annular wall 9a is attached to the annular wall 7d of the first piston body 7.
An annular intermediate chamber C is formed between the first piston body 7 and the second piston body 9 by fitting along the inner circumferential surface of the piston body C.
is formed.

Further, an arc-shaped inner opening window 9C and an annular outer opening window 9d are formed on the lower surface of the second piston body 9, and each opening window 9c. A second extension seat surface 9e and a third extension seat surface 9f are formed on the outer periphery of the extension seat surface 9d, and a double opening window 9c. Four second constant orifices 9g are formed to communicate between the holes 9d (see FIG. 5).

Then, both seat surfaces 9e. 9f and said second
The expansion side disc valve 10 is provided, and the inner opening window 9C is communicated with the intermediate chamber C through four second communication holes 9h, which are small holes (see Fig. 4.5).

Therefore, the inner opening window 9c is connected to the upper liquid chamber through a passage constituted by the second communication hole 9h, the intermediate chamber C, the first constant orifice 71, the opening window 7e, the first communication hole 7f, and the communication passage 7g. It is connected to A. On the other hand, a first annular groove 7k is formed in the upper inner peripheral surface of the first piston body 7, and a communication groove 7m is formed in the boss portion 7C to communicate between the first annular groove 7k and the communication path 7g. Two pieces are formed (see Figure 2). Further, a second annular groove 91 is formed on the lower inner circumferential surface of the second piston body 9, and this second annular groove 91 communicates with the outer opening window 9d through two communication grooves 9j. (See Figure 5).

In addition, a through hole 3a is bored in the axial center of the piston rod 3 upward from the lower end, and the piston rod 3 is located at a position corresponding to the first annular ring 7k and the second annular ring 9i, respectively. A first communication hole 3b and a second communication hole 3c are bored to communicate the first annular groove 7k and the second annular groove 91 with the through hole 3a.

Therefore, the outer opening window 9d includes the communication groove 9J, the second annular groove 91, the second communication hole 3c, the communication hole 3a, the first communication hole 3b, the first annular groove 7k, the communication groove 7m, and the communication path 7g. It communicates with the upper liquid chamber A through a structured passage.

A large diameter communication hole 13a is formed in the lower part of the nut l3 to communicate the communication hole 3a with the lower liquid chamber B. A check valve l4 is provided to allow the flow of hydraulic fluid to the lower fluid chamber B and, conversely, to restrict the flow of hydraulic fluid from the through hole 3a to the lower fluid chamber B. This check valve l4 is the nut l3
A valve body 14a fitted into a communication hole 13a, and a check plate 1 in contact with this valve body 14a.
4b, and a spring 14c that biases the check plate 14b in the valve closing direction.

Furthermore, an adjuster l5 as a variable orifice is rotatably provided in the through hole 3a, sandwiched between an upper thrust push 16 and a lower thrust push l7.

The adjuster 15 is formed into a cylindrical shape with a hollow portion 15a, and has the first communication hole 3b and the second communication hole 3, respectively.
An upper orifice hole 15b and a lower orifice hole 15c are bored in the radial direction at positions corresponding to c, and a flow path is cut off between the first communication hole 3b and the second communication hole 3c and the hollow part 15a. It is formed so that its area can be changed.

Incidentally, the adjustment element l5 is rotated by a control rod l8 provided within the piston rod 3. This control rod 18 extends to the upper end of the piston rod 3, and is rotated by the drive of a motor M provided at a portion of the piston rod 3 that is attached to the vehicle body (not shown). Also,
The motor M is driven by an on-vehicle controller 30. The controller 30 is connected to various sensors 3l for detecting the running condition of the vehicle and an operation switch 32. The drive of the motor M is controlled according to the driving conditions of the vehicle and the operation of the operation switch 32. That is, the control rod 18. The motor M and the controller 30 constitute an aperture control means.

By the way, as shown in FIG. 7, an outer cylinder 19 is provided outside the cylinder 1, and a desired amount of gas is filled in the space between the outer cylinder 19 and the cylinder 1 under pressure. A reservoir chamber D filled with hydraulic fluid is formed.

Further, a base 20 defining the lower liquid chamber B and the reservoir chamber D is provided at the bottom of the cylinder I. This base 20 includes a growth side communication path 20a and a compression side communication path 20a.
A check plate 2l is provided on the upper surface of the base 20 to allow only the flow of hydraulic fluid from the reservoir chamber D to the lower waterfall chamber B in the expansion side communication path 20a. On the lower surface, a first pressure side disc valve 22 and a first pressure side disc valve 22 are provided in contact with the inner seat surface 20c in order to generate a damping force when the hydraulic fluid flows from the lower liquid chamber B to the reservoir chamber D via the overwhelming communication passage 20b. Outer seat surface 2
A second pressure-side disc valve 23 is provided which is in contact with the valve 0d.

The double-pressure side disc valves 22.23 form a two-stage valve in series, and as shown in FIG.
A washer 24 is provided between the first pressure side disc valve 22 and the second pressure side disc valve 23 to separate the two from each other to allow the first pressure side disc valve 22 to bend. Further, a constant orifice 20e is engraved on the outer sheet surface 20d. Next, the operation of the embodiment will be explained.

(a) During the extension stroke First, during the extension stroke in which the piston 2 moves in a direction to narrow the volume of the upper liquid chamber A, as the hydraulic pressure in the upper liquid chamber A increases,
The working fluid in the upper fluid chamber A flows into the lower fluid chamber B. At this time, there are four paths through which the hydraulic fluid flows, as shown in the hydraulic circuit diagram of FIG. 6(a). II. III.
There is I'V.

First, the first path I opens the first growth-side disc valve 8 and opens the second and third growth-side seat surfaces 9e. This is the path to open the second expansion side disc valve 10 at the 9f position. That is, to explain with reference to FIG. 1, the flow is traced from the upper liquid chamber A to the communication path 7g - the first communication hole 7f - the opening window 7e - the intermediate chamber C - the second communication hole 9h - the inner opening window 90 - the outer opening window 9d. This is the route leading to lower liquid chamber B. Next, the second path II passes through the first constant orifice 71, and further passes through the second and third expansion side seat surfaces 9e. 9f
This is the path to open the second extension side disc valve lO at the position. That is, this second route II is the same as the first route I as seen in FIG. This is the distribution channel when the is closed.

Next, the third route III is a route in which the second growth side disc valve 10 is opened at the position of the third growth side seat surface 9f after passing through the first constant orifice 71 and the second constant orifice 9g. be.

In the case of this third route Ill, the same route as the first route I is followed as seen in FIG. This is a distribution route when the second expansion side disc bulge 10 is closed at the position of the second expansion side seat surface 9e when the second expansion side seat surface 9e is closed and flows from the inside opening window 9C to the outside opening window 9d. ．． Next, the fourth path (2) passes through the upper orifice hole l5b and the lower orifice 15c, and then passes through the third expansion side seat surface 9f.
This is the path for opening the second expansion side disc valve IO at the position. To explain this with reference to FIG. 1, from the upper liquid chamber A to the communication path 7g to the communication groove 7m to the first annular groove 7k to the first communication hole 3b to the upper orifice hole 15b to the hollow part 15a to the lower orifice hole 15c to the second Communication hole 3c~second annular hole 91~
This is a path that passes through the communication groove 9j and the outer opening window 9d, opens the second expansion side disc valve 10 at the third expansion side seat surface 9f position, and flows into the lower liquid chamber B.

Therefore, at low piston speeds, the hydraulic fluid flows through the second path II, the third path ■I, and the fourth path ■, and the constant orifice 7i. 9g and orifice holes l5b and 15c, and a damping force with velocity squared characteristics with a constant cross-sectional area due to the second extension side disc bulp 10 and a variable cross-sectional area can be simultaneously obtained. In other words, a speed square characteristic in which the rate of change is small as the speed is low and a rate of change as high as the speed is high, and a speed 2/3 characteristic in which the rate of change is large as the speed is low and the rate of change is small as the speed is high are simultaneously obtained. Therefore, it is possible to cancel out the changes in both rates of change and obtain a characteristic in which the rate of change is almost constant. In addition, in the high piston speed range, both expansion side disc valves 8 and 10 open, and the hydraulic fluid flows through the first path I, resulting in a characteristic that is the sum of the speed characteristics in series to the 273rd power. In the high piston speed range, the rate of change is small in the speed 2/3 power characteristic, so by adding up the speed 2/3 power characteristics, it is possible to suppress the decrease in the rate of change and obtain an almost constant rate of change. Can be done. Further, in this embodiment, by rotating the adjuster l5, both communication holes 3b. 3c, both orifices l5b. By changing the diameter of the valve 15c, the distribution of the opening pressure applied to the second expansion side disc valve 10 in the inner opening window 9c and the outer opening window 9d changes, and the opening timing changes. That is, both orifices 15b. When 15c is throttled, the hydraulic pressure against the growth side disc valve 8.10 increases, opening the valve earlier.
The hard (high damping force) range is shown in Figure 8 (■). And more than that, both orifices 15b. 15c, the opening timing of the expansion side disks 8.10 is delayed, resulting in a medium (medium damping force) range as shown in (■) in the figure, and furthermore, both orifices 15b.15c are opened. When 15c is opened, it becomes the soft (low damping force) range shown in the figure. The opening timing of both expansion side disc valves 8.10 is determined by each opening window 7, e. 9c. By adjusting the area of 9d, the pressure receiving area of both valves 8 and 10 can be changed to any desired setting.
It is also possible to adjust the stiffness of both extension side disc valves 8.10.

In addition, during the extension stroke as described above, the check plate 21 of the base 20 is opened, and the hydraulic fluid in the reservoir chamber D is changed to the lower fluid in order to compensate for the volume change caused by the withdrawal of the piston rod 3. It flows into chamber B. (B) During the pressure stroke During the pressure stroke in which the piston 2 moves in the direction of narrowing the volume of the lower liquid chamber B, the piston 2 is connected to the upper liquid chamber A as shown in the hydraulic circuit diagram in FIG. 3 between lower liquid chamber B
Two parallel paths V, Vl. The hydraulic fluid flows through (2).

That is, the first path V is connected from the lower liquid chamber B to the pressure side communication
This is the route that opens the pressure-side disc valve 6 and reaches the upper liquid chamber A through A. In this case, a damping force having a velocity ⅔ power characteristic is obtained between the compression side disc valve 6 and the seat surface 7b.

In addition, the second path Vl is opened from the lower liquid chamber B by opening the check valve l4 provided in the nut 13 at the lower end of the piston rod 3, and opening the communication hole 13a, the through hole 3a, and the hollow part 15.
a. Upper orifice hole 15b. First communication hole 3b. First annular groove 7k. Communication groove 7m. Upper liquid chamber A through communication path 7g
This is the route that leads to. In this case, a damping force having a square velocity characteristic is obtained at the upper orifice 15b.

Further, the third route (2) is similar to the second route II from the hollow part 15a to the lower orifice hole 15c. Second communication hole 3c, second annular hole 91, communication groove 9j
．． Outside opening window 9d. 2nd constant orifice 9g.
Inner opening window 9c. Second communication hole 9h. Intermediate chamber C. First constant orifice 71. Opening window 7e. First communication hole 7f
．． This is a route that reaches the upper liquid chamber A through the communication path 7g.

Therefore, in the pressure stroke, in the low piston speed range, the upper and lower orifices 15b. 15c or constant orifice 7
i. 9 g, a damping force with a speed squared characteristic is obtained, and in the middle and high piston speed ranges, a damping force with a speed 2/3 characteristic is obtained by the compression side disc valve 6.

On the other hand, during this pressure stroke, the hydraulic fluid also moves between the lower fluid chamber B and the reservoir chamber D via the base 20. That is, the hydraulic fluid in the lower fluid chamber B flows from the pressure side communication path 20b to the lth
The pressure side disc valve 22 is opened, and in the case of a low piston speed range, the stamped constant orifice 2 is opened.
0e, and in the middle and high piston speed ranges,
The second pressure side disc valve 23 is opened to flow into the reservoir chamber D. Therefore, even in the pressure stroke, the piston 2 and the base 20
In the low piston speed range, the speed square characteristic and the speed 2/
In addition, in the medium and high piston speed ranges, a characteristic is obtained by adding the speed 2/3 power characteristic, so the characteristic becomes a linear characteristic. Also, in the case of this pressure stroke, by rotating the adjuster l5,
By changing the flow path cross-sectional area of both orifice holes 15b and 15c, the damping force characteristics can be changed to a hard range (2), a medium range (2), and a soft range (2), as shown in FIG. In addition, the dotted line is the base 20
The damping force characteristics are shown.

As explained above, in the damping force control system for the hydraulic shock absorber of this embodiment, the damping force characteristics are controlled over the entire speed range from the low piston speed range to the medium and high piston speed ranges.
In addition, linear damping force characteristics can be obtained across the entire range from hard to soft, making it possible to control damping force with an excellent balance between handling stability and ride comfort across all ranges. are doing.

In addition, in the damping force control system of the hydraulic shock absorber of this practical example, the opening timing of both expansion side disc valves 8.10 is
The valve rigidity of both extension side disc valves 8.10 and each opening window 7e. 9c. 9d area or constant orifice 7
i. 9e and the upper and lower orifices 15b. Since it can be set arbitrarily depending on the cross-sectional area of 15c, there are many setting elements, and the setting is characterized by a high degree of freedom.

Furthermore, in the embodiment, upper and lower orifices 15b with a variable cross-sectional area are provided in the middle of the path (3) communicating with the outer opening window 9d of the second expansion-side disc valve 10. 15c, this orifice 15b. 15c, it is possible not only to simply obtain the damping force of the orifice characteristic, but also to change the opening timing of the second extension side disc valve IO,
It has the characteristics that it is possible to obtain a difference in characteristics that is greater than a mere change in the cross-sectional area of the flow path, that the range setting width of the damping force characteristic is increased, and that the degree of freedom in setting is high.

In addition, since the piston 2 is formed by being divided into the first piston body 7 and the second piston body 9, the pressure receiving area and valve rigidity of both extension side disc valves 8 and 10 can be set independently. It is characterized by a high degree of freedom in setting the damping force.

Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to these embodiments, and there may be design changes within the scope of the invention. included.

For example, in the embodiment, the present invention was applied to the extension stroke side of the piston, but it can also be applied to the compression stroke side. Further, in the embodiment, an example was shown in which the communication passage that communicates the outer opening window and the upper liquid chamber is formed in the piston rod, but it can also be formed in the piston body. Further, in the embodiment, an example was shown in which the variable orifice was provided in the middle of the communication path to the second expansion side disc valve, but the variable orifice was provided in the middle of the communication path to the opening window of the first expansion side disc valve (for example, the first communication hole 7f ) may be placed in the middle. (Effects of the Invention) As explained above, in the damping force control system for a hydraulic shock absorber of the present invention, the communication path that communicates the opening window formed in contact with at least one of both disc valves with the other liquid chamber. Since a variable orifice is provided in each damping force range, linear damping force characteristics are obtained with respect to piston speed from low piston speed range to medium and high piston speed range, improving handling stability in all ranges. At the same time, the effect of being able to achieve both ride comfort and
The effect of widening the variable range of range settings and improving the degree of freedom in setting can be obtained.

In addition, in the invention as claimed in claim 2, since the piston is formed by being divided into the first piston and the second piston, the pressure receiving area and valve rigidity of the first and second disc valves can be independently and arbitrarily set. Therefore, it is possible to obtain the effect that there is a high degree of freedom in setting the damping force characteristics.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the main parts of a hydraulic shock absorber to which the damping force control system of the present invention is applied, Fig. 2 is a plan view showing the top surface of the first piston body, and Fig. 3 is a top view of the first piston body. FIG. 4 is a plan view showing the top surface of the second piston body of the embodiment, FIG. 5 is a bottom view showing the bottom surface of the second piston body, and FIG. Figure 6 (b) is a hydraulic circuit diagram during the pressure stroke of the hydraulic shock absorber; Figure 7 (a) is a sectional view showing the base of the hydraulic shock absorber; Figure 7 (opening) is an enlarged sectional view of part F, Figure 8 is a graph showing the relationship between the damping force generated during the extension stroke of the hydraulic shock absorber and the piston speed, and Figure 9 is the graph showing the relationship between the damping force generated during the extension stroke of the hydraulic shock absorber and the piston speed. It is a graph showing the relationship between generated damping force and piston speed. A... Upper liquid chamber B... Lower liquid chamber ■... Cylinder 2... Piston 3a... Through hole (communicating path) 3b... First communicating hole (communicating path) 3c... 2nd communication hole (communication path) 7... L piston body 7g... Communication path 7h... 1st expansion side seat surface (first seat surface) 7k...
・First annular groove (communicating path) 7 m --- First communicating groove (communicating path) 8 --- First extension side disc valve l 1 l (first disc valve) 9 --- Second piston body 9 d. ...Outside opening window 9e...Second extension side seat surface (second seat surface) 9f...
・Third growth side seat surface (second seat surface) 91...Second annular groove (communication path) 9j...Second communication groove (communication path) 10...Second growth side disc valve ( 2nd disc valve) 5a...Hollow part (communicating path) 15...Adjustor (variable orifice) 5b...Upper orifice hole 5c...Lower orifice hole Patent Application Hitoatsugi Auto Parts Co., Ltd. No. Figure 2 Figure 3 Figure 4 Figure 9d Figure 5

Claims (1)

[Claims] 1) A piston that is provided in a cylinder filled with hydraulic fluid and divided into one liquid chamber and the other liquid chamber, and a piston that is arranged in series on one end surface side of the piston. a first disc valve and a second disc valve, an opening window formed in one end surface of the piston to be opened and closed by at least one of the disc pulps, and the opening window and the other liquid chamber. A damping force control system for a hydraulic shock absorber, comprising: a variable orifice provided in the middle of a communicating path; and an aperture control means for controlling an amount of aperture of the variable orifice. 2) The piston according to claim 1, wherein the piston is formed of a first piston having a first seat surface that contacts the first valve, and a second piston having a second seat surface that contacts the second valve. damping force control system for hydraulic shock absorbers.