JPH0361737A - Variable damping force hydraulic shock absorber - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a variable damping force hydraulic shock absorber applied to a vehicle suspension. It relates to an inverted type that is connected to a vehicle body.

(Prior Art) Conventionally, as an inverted type variable damping force type hydraulic shock absorber, for example, one described in Japanese Patent Laid-Open No. 58-97334 is known.

This hydraulic shock absorber has a structure in which a pressure side damping valve is provided on the base, a variable orifice is provided in parallel with this, and an orifice hole is provided in the piston.

(Problems to be Solved by the Invention) However, such a conventional variable damping force hydraulic shock absorber has the following problems.

■ It has a structure in which the damping force is variable only during the compression side stroke,
It is not possible to change the damping force during the rebound stroke.

■ Because the structure is such that fluid is not supplied directly to the lower chamber from the reservoir chamber but via the upper chamber, if the piston hole restricts the fluid flow rate from the upper chamber to the lower chamber too much during the pressure side stroke, , the amount of fluid supplied to the lower chamber is insufficient, resulting in negative pressure and cavitation. For this reason,
The overwhelming damping force cannot be set high.

■ A linear damping force characteristic cannot be obtained with respect to piston speed.

The present invention was made with attention to such problems, and
The damping force can be made variable in both the overwhelming stroke and the rebound stroke, and linear damping force characteristics can be obtained in both strokes, and cavitation does not occur in both the upper and lower chambers, and the damping force range is wide. It is an object of the present invention to provide a variable damping force type hydraulic shock absorber that can have a wide variable range of damping force.

(Means for Solving the Problems) In order to achieve the above-mentioned object, in the variable damping force hydraulic shock absorber of the present invention, a guide member having a rod insertion hole is provided at the lower end, and a base is provided at the upper end. a cylinder tube, a piston that defines the cylinder tube into an upper chamber and a lower chamber and is connected to a piston rod inserted into the cylinder tube from a rod insertion port; an outer tube that forms an outer chamber communicating with the lower chamber via a lower communication passage and a reservoir chamber defined by the outer chamber and the upper chamber above the cylinder tube; and an outer tube formed on the base; The upper chamber is in communication with the reservoir chamber through a first damping valve and a second damping valve arranged in series.
First and second inner annular grooves that are formed on the contact surfaces of the communication passage, the first damping valve, and the second damping valve and communicate with the first communication passage, and first and second outer annular grooves formed on the outer periphery thereof. ,
A second communication passage communicates the first communication passage between the two damping valves and the outer chamber, and a check passage communicates the reservoir chamber with the upper chamber.

(Function) The function of the variable damping force type hydraulic shock absorber of the present invention will be explained based on the fluid circuit diagram shown in FIG. This Figure 1 shows the fluid flow path in the configuration of the present invention, in which a is an upper chamber, b is a lower chamber, C is an outer chamber, d is a reservoir chamber, e is a lower communication path, and f is a The first communication path, g is the first damping valve, h
is a second damping valve, j is a second communication passage, and k is a check passage.

First, during the extension stroke, the volume of the lower chamber a in the cylinder tube is reduced and the upper chamber a is expanded.

According to this volume change, the fluid in the lower chamber flows through the lower communication passage e.
It flows into the outer chamber C through the base, then passes through the second communication path j of the base, flows into the first communication path f between the two damping pulps g and h, and passes through the first communication path f to the second damping pulp. It flows into the reservoir chamber d through both the inner and outer annular grooves of the valve h.

Therefore, a damping force having a velocity 2/3 power characteristic is generated in series at the inner and outer peripheral seat surface positions of the second damping valve h. In this way, a damping force with a speed 2/3 characteristic in which the rate of change decreases as the piston speed increases is obtained in series, so the decrease in the rate of change of the damping force is suppressed and a linear damping force is achieved. can get.

Incidentally, an amount of fluid corresponding to the volume of the piston rod withdrawn from the cylinder tube is supplied to the upper chamber a from the reservoir chamber d via the check passage k of the base. Therefore, the upper chamber a does not become under negative pressure, and cavitation does not occur.

Next, during the overwhelming stroke, the volume of the lower chamber a is expanded and the upper chamber a is contracted in the cylinder tube.

According to this volume change, the fluid in the upper chamber a passes through the first communication passage f, passes through both the inner and outer annular grooves of the first damping valve g, and reaches the position between the two damping valves g and h in the first communication passage f. From this position, a part of the fluid passes through the second communication path j and enters the outer chamber C.
and flows into the upper chamber a through the lower communication passage e.

Further, the remaining fluid (the volume of the piston rod entering the lower chamber) further advances through the first communication path f and flows into the reservoir chamber d via the inner and outer circumferential annular grooves of the second damping valve h.

Therefore, a damping force having a velocity 2/3 characteristic is generated in series at both the inner and outer seat surface positions of the first damping valve g and at both the inner and outer seat surface positions of the second damping valve h. In other words, since a damping force with a velocity 2/3 characteristic in which the rate of change decreases as the piston speed increases is obtained in series, a linear damping force can be obtained by suppressing a decrease in the rate of change of the damping force. .

In addition, since the upper chamber a and the lower chamber A are communicated via the second communication passage j, the outer chamber C1 lower communication passage e, and the first damping valve g, the first damping valve g is In terms of force characteristics, during this pressure stroke, the outer chamber C and the lower chamber communicating therewith do not become negative pressure, and cavitation does not occur.

(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. 2 is a sectional view showing a variable damping force type hydraulic shock absorber according to the first embodiment of the present invention, and numeral 1 in the figure is a cylinder tube.

The cylinder tube l has a cylindrical shape, has a guide member 2 at its lower end, a base 3 at its upper end, and is filled with a fluid such as oil.

As shown in the enlarged view of the main part of FIG. 3, the guide member 2 is formed with a rod insertion opening 2atJS, and this rod insertion opening 2a is provided with a vacuum seal 2b and a stop rubber 20. ing. A seal member 4 having an oil seal 4a is fitted and fixed to the outer periphery of this guide member 2.

Returning to FIG. 2 and continuing the explanation, the cylinder tube l
A piston 5 is slidably provided in the cylinder 1, and defines the interior of the cylinder 1 into an upper chamber A and a lower chamber B.

The piston 5 is also provided with a compression damping valve 5a and a rebound damping valve 5b, which open depending on the stroke direction to generate a damping force (see FIG. 3). In addition, 5c is a compression side communication path, and 5d is a growth side communication path.

The piston 5 is fastened with a nut 6a to the tip of a piston rod 6 inserted into the cylinder tube 1 through the rod insertion port 2a.

The lower end of the piston rod 6 is fastened to the bottom cap 7a of the strut tube 7 with a nut 7b.

The lower end of the strut tube 7 is fitted and fixed to the knuckle spindle 8, and the upper end is provided with a sub-jing seat 9 that supports the lower end of a spring (not shown). Furthermore, a bound stopper IO is provided at the bottom of the strut tube 7.

An outer tube II is provided on the outer periphery of the cylinder tube I and extends above the cylinder tube I. This outer tube 11 has an inner periphery at its lower end fitted into the seal member 4, an inner periphery at an upper middle section fitted into the base 3, and an upper end fitted to the vehicle body. It will be done. The outer tube 11 is provided to be slidable relative to the strut tube 7 in the vertical direction via two upper and lower bearings lla and llb.

Further, by this outer tube 11, an outer chamber C is formed on the outer periphery of the cylinder tube 1, and the outer chamber C is communicated with the lower chamber B via the lower communication passage 2d formed in the guide member 2. A reservoir chamber is formed on the upper side of the chamber and filled with a desired amount of fluid under pressure from the enclosed gas.

Next, moving to FIG. 4, the structure of the base 3 will be explained in detail.

As shown, the base 3 is connected to the support rod 12.
Retainer 13. Washer 14. Second damping valve 15.
Second body 16. Second check valve 17. Washer I
8. Retainer 19. washer 20, first damping valve 21
．． First body 22. First check valve 23. Washer 24. Attach the retainer 25 in order, and finally attach the nut 26.
It is concluded and constructed. An intermediate chamber E is formed between the first body 22 and the second body 16, and a through hole 1 is provided in the support rod 12, which opens into the upper chamber A at the axial center.
2a is formed.

More specifically, the first body 22 has a first inner annular groove 22d and a first outer annular groove 22f doubly arranged inside and outside on the upper surface.
is formed. Both grooves 22d and 22f are formed in a circular ring shape, and each of the inner sheet surface 2
2g and an outer seat surface 22h are formed, and the first inner annular member 22d has first communication grooves 22j and 22 formed on the upper surface of the first body 22, and a through hole 12a formed in the support rod 12. It communicates with the first outer ring 22f via the first boats 12b, 12b (see Fig. 6).
.

The first body 22 also includes a first communication hole 22a that communicates between the upper chamber A and the first inner annular chamber 22d, and a first check passage 22b that communicates the reservoir chamber with the upper chamber A.
A base communication path 22c is formed that communicates the intermediate chamber E and the outer chamber C. The first communication hole 22a is connected to the first communication hole 22a.
The first check flow path 22b is restricted by the damping valve 21, and the first check flow path 22b is configured to allow only flow from the reservoir chamber to the upper chamber A by the first check valve 23.

Next, on the upper surface of the second body 16, a second inner annular ring 16a and a second outer annular ring 16g are formed in double layers, inside and outside. Both grooves 16a and 16g are formed in a hollow annular shape, and an inner seat surface 16h and an outer seat surface 16j are respectively formed on the outer periphery of the grooves, and the second inner annular groove 16a is
In the second communication groove 16 formed on the upper surface of the second body 16,
16m and the through hole 12a formed in the support rod 12 and the second bow)-12c, 12c to the first outer annular member 1
6g (see Figure 5).

Further, an inner annular groove 16b and an outer annular groove 16c are formed on the lower surface of the second body 16, doubling the inner and outer sides. The passage 16d is opened and the second check valve 17 allows only the flow from the reservoir chamber to the intermediate chamber E. In addition, the inner annular groove 16b
A second communication hole 16e for communicating the intermediate chamber E with the reservoir chamber is formed between the inner groove 16a and the second inner groove 16a.
This second inner annular ring 16a can be opened and closed by a second damping valve 15.

Note that the second check valve 17 has an inner annular iR1.
A communication hole 17a is formed that communicates 6b with the intermediate chamber E.

In the through hole 12a, a cylindrical adjuster 27 having a hollow portion 27d is provided with thrust bushes 28, 29 at the top and bottom.
It is supported by and rotatable in the circumferential direction. still,
The lower end opening of this through hole 12a is closed by a lower thrust bush 29.

This adjuster 27 includes the first boats 12b, 12b,
A lower large-diameter orifice hole 27a and an upper large-diameter orifice hole 27c are bored in the radial direction at positions corresponding to the second boats 12c, 12c, respectively. The interior of the hollow portion 27d is vertically defined by the center bush 33 fitted within the hollow portion 27d.

Further, as shown in FIGS. 5 and 6, the adjuster 27 at the positions corresponding to the first ports 1-2b, 12b and the second boats 12c, 12c has a lower large-diameter orifice hole. A lower small-diameter orifice hole 27b and an upper small-diameter orifice hole 27e are formed with a phase shift of about 45 degrees from the upper large-diameter orifice hole 27a and the upper large-diameter orifice hole 27c, respectively.

In addition, FIGS. 5 and 6 show the upper large diameter orifice hole 27c.
and the lower large diameter orifice hole 27a is the second bow)-12c
and a state in which it communicates with the first port 12b is shown.

Further, the adjuster 27 is connected via a control rod 30 to a motor actuator 31 attached to the upper end of the reservoir chamber (see FIG. 2), and is rotated by the drive control of this motor actuator 31. It looks like this. With this rotation of the adjuster 27, the first
The amount of fluid flowing between the ports 12b, 12b and the second ports 12c, 12c is switched in three stages.

Note that 32 is a seal.

As explained above, in the first embodiment of the present invention, the base 3
The upper chamber A, the outer chamber C, and the reservoir chamber are defined by the passageway formed in the base 3.
Each chamber A, C, and D are connected to each other, that is, the fourth chamber.
As shown in FIG. 7, the first communication hole 22a, the first inner annular groove 22d, the first outer annular groove 22f, the intermediate chamber E, the inner annular groove 16b, the second communication hole 16e, the second inner annular groove 16a, and the second inner annular groove 16a.
The outer annular groove 16g constitutes the first communication path I in the claims.

Further, the base communication path 22c constitutes a second communication path II in the claims.

Further, the first check flow path 2 including the first check valve 23 constitutes the check flow path (2) in the claims.

Furthermore, in this embodiment, a first bypass passage (2) is formed between the first inner annular groove 22d and the first outer annular groove 22f in parallel with the inner part of the first damping valve 21, and this first bypass passage ■ Lower large and small orifice holes 27a, 27b in the middle of
A first variable orifice F is provided.

Further, between the second inner annular groove 16a and the second outer annular groove 16g, a second
A bypass path V is formed, and in the middle of this second bypass path V, a second variable orifice G whose constituent elements are upper large and small orifice holes 27c and 27e is provided.

The reservoir chamber includes a second check passage 16d, an outer annular groove 16c, a second check valve 17, an intermediate chamber E,
A check flow path (2) constituted by the base communication path 22c communicates with the outer chamber C in a manner that only allows fluid to flow from the reservoir chamber side.

Next, the operation of the embodiment will be explained with reference to the circuit diagram shown in FIG.

(a) During the extension stroke During the extension stroke, the lower chamber B in the cylinder tube l
The volume of is reduced and the upper chamber A is enlarged.

According to this volume change, the fluid in the lower chamber B flows into the outer chamber C via the lower communication path 2d of the guide member 2, flows into the intermediate chamber E through the base communication path 22c, and further flows into the intermediate chamber E through the base communication path 22c. It flows into the reservoir chamber through the first communication path (2) or the second bypass path (V).

Both roads in this case 1. The flow rate of V is determined by the second variable orifice G.
Based on this flow rate, a damping force is generated by the second damping valve 15 or the second variable onofice G.

This damping force characteristic applies to the orifice holes 27c and 27e of the second variable orifice G when the piston speed is low.
, a damping force with a speed squared characteristic is generated, and a low damping force with a speed 2/3rd power characteristic is generated in series on the outer seat surface 16j side of the second damping valve 15, resulting in a damping force characteristic linearly proportional to the piston speed. is obtained. On the other hand, when the piston speed is medium or high, or when the second variable orifice G is closed, the inner seat surface lGh of the second damping valve 15
A high damping force and a low damping force with a 2/3 power characteristic are obtained in series on the side and the outer seat surface 16j side, and in this case also, a characteristic linearly proportional to the piston speed is obtained.

In this embodiment, the range of the damping force characteristics can be changed by rotating the adjuster 27. That is, in the rotational position of the adjuster 27 in which the upper large-diameter orifice hole 27c is aligned with the second port 12c as shown in FIG. 4, the characteristics of the low damping force range as shown on the expansion side 5OFT in FIG. 8 are obtained. In the rotation position of the adjuster 27 in which the upper small-diameter orifice holes 27e are aligned, the characteristics are in the medium damping force range shown in the expansion side MEDIUM in FIG. In the dynamic position, the characteristics are in the high damping force range shown in the expansion side HARD in FIG.

Incidentally, an amount of fluid corresponding to the volume of the piston rod 6 exited from the cylinder tube 1 is supplied to the upper chamber A from the reservoir chamber via the check flow path III. Therefore, even if the second damping valve 15 is made to have high damping force characteristics, the upper chamber A does not become a negative pressure, and cavitation does not occur.

Therefore, the damping force characteristic during the extension stroke can be made variable, and the damping force characteristic can be varied over a wide range.

Note that during this extension stroke, the extension damping valve 5b also opens in the piston 5, and a damping force is generated.

(b) During the overwhelming stroke During the overwhelming stroke, the volume of the lower chamber B is expanded and the upper chamber A is decreased in the cylinder tube l.

According to this volume change, the fluid in the upper chamber A flows into the intermediate chamber E through the first communication path I or the first bypass path (2) parallel to it.

A part of the fluid that has flowed into the intermediate chamber E in this way is
It flows into the outer chamber C through the second communication path II, and further flows into the lower chamber B through the lower communication path 2d. Further, the remaining fluid (the volume of the piston rod 6 entering the lower chamber B) further advances through the first communication path I and flows into the reservoir chamber.

Therefore, the first damping valve 21. A damping force is generated in the second damping valve 15, the first variable orifice F, and the second variable orifice G.

In this case as well, as in the case of the extension stroke, a damping force characteristic linear with respect to the piston speed can be obtained, and by rotating the adjuster 27, the damping force characteristic can be changed as shown in FIG. range (pressure side 5OFT, MEDIUM,
HARD) can be changed.

Incidentally, since the upper chamber A and the lower chamber B are communicated with each other via the first damping valve 21 midway through the first communication passage I or the first bypass passage and the second communication passage II, the first Even if the damping valve 21 has a high damping force characteristic, the outer chamber C and the lower chamber B communicating with the outer chamber C do not become negative pressure during this overwhelming stroke, and cavitation does not occur. In addition, even if the flow rate from the upper chamber A is insufficient due to piston speed etc. and the outer chamber C and lower chamber B are likely to become negative pressure, in such a case, the check flow path Since the fluid is supplied from the reservoir chamber, negative pressure will not occur, and cavitation will not occur.

Therefore, even in the case of the compression side stroke, the damping force characteristics can be made variable, and the damping force characteristics can be varied over a wide range.

In addition, during this compression side stroke, the compression side damping valve 5a is opened even in the piston 5, and a damping force is generated.

Furthermore, in this first embodiment, since the outer tube 11 is supported by the strut tube 7, the support rigidity is extremely high, and the strength is particularly high against lateral loads, making it ideal for vehicle suspension. It has the characteristic that

Next, a second embodiment shown in FIG. 9 will be described. still,
In describing this embodiment, the same components as in the first real box example are given the same reference numerals, and only the differences will be explained.

This embodiment is an example in which a spool that slides in the vertical direction is used as the variable orifice, instead of a rotating type adjuster as in the first practical example.

That is, in FIG. 9, 200 is a spool, which has an upper annular groove 20 on its outer periphery that corresponds to the second ports 12c, 12c.
A lower annular groove 202 is formed which corresponds to the first and second ports 12b, 12b.

Therefore, in this embodiment, by sliding the spool 200 up and down, the damping force range can be changed to arbitrary or fixed.

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. For example, in the embodiments, a strut type was shown, but
It is also possible to adopt a configuration in which strut tubes and sub-Jings are eliminated.

Further, although the piston is provided with a damping valve, the upper chamber and the lower chamber may not communicate with each other at all on the piston side.

(Effects of the Invention) As explained above, in the variable damping force type hydraulic shock absorber of the present invention, since the damping force is configured as described above, the damping force can be made variable in both the compression side stroke and the rebound side stroke. In addition, linear damping force characteristics can be obtained in any stroke, cavitation does not occur in the upper and lower compartments, and the damping force range can be varied widely.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing the fluid flow path of the variable damping force type hydraulic shock absorber of the present invention, FIG. 2 is a sectional view showing the whole of the first embodiment of the shock absorber of the present invention, and FIGS. 3 and 4 is a sectional view showing the main part of the first actual journey example, FIG. 5 is a sectional view taken along V-V in FIG. 4, FIG. 6 is a sectional view taken along Vl-Vl in FIG. 4, and FIG. 7 is a sectional view showing the first embodiment. 8 is a diagram showing damping force characteristics with respect to piston speed of the first embodiment, and FIG. 9 is a sectional view showing essential parts of the second embodiment of the present invention. l...Cylinder tube 2...Guide member 2a...Rod insertion port 2d...Lower communication passage 3...Base 5...Piston 6...Piston rod 11-...Outer tube 16a=... Second inner annular groove 16g - Second outer annular groove 22 d - First inner annular groove 22f - First outer annular groove A - Upper chamber B - Lower chamber C - Outside Chamber D: Reservoir chamber: First communication path II: Second communication path: Check flow path

Claims (1)

[Claims] 1) A cylinder tube with a guide member provided at the lower end and a base provided at the upper end, each having a rod insertion port; the cylinder tube is defined into an upper chamber and a lower chamber; A piston is connected to a piston rod inserted into the tube, and an outer chamber is provided surrounding the cylinder tube and communicates with the lower chamber via a lower communication passage on the outer periphery of the cylinder tube. an outer tube forming a reservoir chamber defined by an outer chamber and an upper chamber by a base; and an outer tube formed in the base and communicating the upper chamber with the reservoir chamber via a first damping valve and a second damping valve arranged in series. The first and second communication passages are formed on the contact surfaces of the first communication passage, the first damping valve, and the second damping valve, respectively, and communicate with the first communication passage.
An inner annular groove, first and second outer annular grooves formed on the outer periphery thereof, a second communication passage that communicates between the position between both damping valves of the first communication passage and the outer chamber, and a reservoir chamber that communicates with the upper chamber. A variable damping force type hydraulic shock absorber, characterized in that it is equipped with a check flow path for checking, and a variable damping force type hydraulic shock absorber.