JPH0366942A - Hydraulic damper of variable damping force type - Google Patents

Abstract

PURPOSE:To widen the range of variable damping force by arranging an actuator, between a base and an upper end attachment portion of an outer tube, for actuating a variable orifice attached to a base to make fluid flow rate variable. CONSTITUTION:During extension stroke, a lower chamber B contracts, an upper chamber A extends, fluid flows through a lower passage 2d to an outer chamber C and through a 2nd passage to a upper chamber A to produce damping force. Flow rate of the fluid through the 2nd passage is varied with a variable orifice 27 varied with a rotary actuator 31. During compression stroke, fluid of the amount corresponding to the volume of the piston rod 6 coming out of a cylinder tube 1 is supplied through a check passage to the upper chamber A. Therefore, the pressure in the upper chamber A does not become negative and accordingly cavitation is prevented from being produced. Thus, the range of variable damping force is widened.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a variable damping force type hydraulic shock absorber applied to a vehicle suspension, and in particular, the piston rod side is connected to the axle, and the cylinder tube side is connected to the vehicle body. It relates to an inverted type that is connected to a.

(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 was provided with a variable orifice that changed the damping force characteristics.

An actuator for operating this variable orifice was attached to the vehicle body separately from this shock absorber.

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

■ Since the hydraulic shock absorber and actuator are separate,
When assembling to the vehicle body, it is sometimes necessary to match the positions of the two parts with respect to the vehicle body, which results in poor assembly work efficiency and tends to reduce assembly accuracy.

■ It is necessary to secure mounting space for both the hydraulic shock absorber and the actuator on the vehicle body, and the degree of freedom in mounting it on the vehicle is low.

■ During the overwhelming stroke, fluid is only supplied to the lower chamber from the upper chamber via the damping force generating means, and no fluid is supplied from the reservoir chamber. If the fluid flow rate from the chamber to the lower chamber is restricted too much, the amount of fluid supplied to the lower chamber becomes insufficient, resulting in negative pressure and cavitation. For this reason, the overwhelming damping force cannot be set high.

The present invention has focused on these problems, and has developed a variable damping force liquid that has good assembly workability, high accuracy in one assembly, has a large degree of freedom in mounting on vehicles, and can further widen the variable range of damping force. The purpose is to provide a pressure buffer.

(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. cylinder tube,
The cylinder tube is defined into an upper chamber and a lower chamber, a piston connected to a piston rod inserted into the cylinder tube from a rod insertion port, and a lower communication passage provided surrounding the cylinder tube and provided on the outer periphery of the cylinder tube. an outer tube forming an outer chamber communicating with the lower chamber through the cylinder tube, and forming a reservoir chamber defined by the outer chamber and the upper chamber above the cylinder tube;
a first communication passage that is formed in the base and communicates between the upper chamber and the reservoir chamber; a second communication passage that communicates between the upper chamber and the outer chamber; and a check passage that communicates the reservoir chamber with the upper chamber; A variable orifice is provided on the base so as to be able to change the fluid flow rate of the communication passage, and an actuator is provided between the upper end attachment portion of the outer tube and the base to operate the variable orifice.

(Function) The operation of the variable damping force type hydraulic shock absorber of the present invention will be explained.

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

According to this volume change, the fluid in the lower chamber flows into the outer chamber through the lower communication passage, and further flows from the outer chamber into the upper chamber through the second communication passage in the base. A damping force can be generated as the fluid flows.

Further, at this time, the damping force range can be changed by changing the flow rate of fluid in the second communication path using the variable orifice.

In addition, during the pressure side stroke, an amount of fluid corresponding to the volume of the piston rod withdrawn from the cylinder tube is supplied to the upper chamber from the reservoir chamber via the check passage. Therefore, the upper chamber does not become under negative pressure and cavitation does not occur.

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

According to this volume change, a part of the fluid in the upper chamber flows to the outer chamber through the second communication passage, and further flows into the lower chamber via the lower communication passage. Further, the remaining fluid (an amount of fluid corresponding to the volume of the piston rod that has entered the cylinder tube) flows into the reservoir chamber through the first communication path.

A damping force can be generated by this fluid flow.

Further, at this time, the damping force range can be changed by changing the flow rate of the fluid in both communication passages using the variable orifice.

Note that during this pressure stroke, the fluid in the upper chamber is supplied to the lower chamber, so the lower chamber does not become under 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. 1 is a sectional view showing a variable damping force type hydraulic shock absorber according to a first embodiment of the present invention, and 1 in the figure is a cylinder tube.

The cylinder tube 1 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. 2, the guide member 2 is formed with a rod insertion opening 2a, a pressure reducing seal 2b is provided in the rod insertion opening 2a, and a stop rubber 2c is provided in the rod insertion opening 2a. It is being And this guide member 2
A seal member 4 having an oil seal 4a is fitted and fixed on the outer periphery of the oil seal 4a.

Returning to FIG. 1 and continuing the explanation, the cylinder tube 1
A piston 5 is slidably provided in the cylinder 1 and defines the inside 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. 2). In addition, 5C is an overwhelming communication path, and 5d is an expansion 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 l from the rod insertion opening 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 spring seat 9 that supports the lower end of a spring (not shown). Further, a bound stopper 10 is provided at the bottom of the strut tube 7.

An outer tube 11 is provided on the outer periphery of the cylinder tube 1 and extends above the cylinder tube 1. This outer tube 11 has an inner periphery at its lower end fitted into the sealing member 4, an inner periphery at an upper middle part fitted into the base 3, and is fitted and fixed into the upper end opening. A mounting portion 11e having a threaded portion lid for mounting the upper end portion of the outer tube 12 to the vehicle body is provided on the upper lid member 11c.

The outer tube 11 is provided so as to be slidable relative to the strut tube 7 in the vertical direction via two upper and lower bearings 11a and 11b.

Further, by this outer tube 11, an outer chamber C is formed on the outer periphery of the cylinder tube l, 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. 3, 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 18
．． Retainer 19. washer 20, first damping valve 2
1. First body 22. First check valve 23. Washer 24. Attach retainer 25 in order, and finally nut 2.
It is constructed by fastening with 6.

An intermediate chamber E is formed between the first body 22 and the second body 16.

The first body 22 has a first communication hole 22a that communicates the upper chamber A with the intermediate chamber E, a first check passage 22b that communicates the reservoir chamber with the upper chamber A, and a first check passage 22b that communicates the upper chamber A with the intermediate chamber E, and between the intermediate chamber E and the outer chamber C. A base communication path 22c is formed to communicate with the base. The first communication hole 22a is constricted by the first damping pulp 21, and the first check flow path 22b is configured to allow flow only from the reservoir chamber to the upper chamber A by the first check valve 23. It has become.

Next, in the second body 16, an upper annular groove 16a is formed on the upper surface (see FIG. 5), and an inner annular groove 16b and an outer annular groove 16c are formed on the lower surface in double layers, both inside and outside. The outer annular groove 16c is opened with a second check flow path 16d that communicates the reservoir chamber with the intermediate chamber E.
The second check valve 17 allows only flow from the reservoir chamber to the intermediate chamber E. Also,
A second communication hole 16e that communicates the intermediate chamber E with the reservoir chamber is formed between the inner annular groove 16b and the upper annular groove 16a, and the upper annular groove 16a can be opened and closed by the second damping valve 15. There is.

The second check valve 17 has an inner annular groove 16.
A communication hole 17a is formed that communicates the space 17b with the intermediate chamber E.

The support rod 12 has a through hole 12a that opens into the upper chamber A at its axial center, and in the radial direction, an upper annular hole 12b that communicates with the reservoir chamber and an upper annular hole 12b through a communication groove 16f. A lower boat 12c is formed which communicates with the groove 16a.

In the first through hole 12a, a cylindrical adjuster 27 having a hollow portion 27c is provided with thrust bushes 28 and 29 at the top and bottom.
It is supported by and rotatable in the circumferential direction.

This adjuster 27 has an upper orifice hole 27a and a lower orifice hole 27b formed therein, forming a variable orifice.

In addition, FIG. 4 is a cross-sectional view of rV-rV in FIG. 3, and FIG.
This is a sectional view taken along the line v-■ in FIG. 3, and as shown in both figures, the upper boat 12b and the lower boat 12C are formed in two locations facing each other, and correspondingly, the upper annular groove 1
Two communication grooves 16f are also formed to communicate the lower boat 12C with the lower boat 6a. Therefore, the cross-sectional views in FIGS. 1 and 3 show the state cut along the line III--III in FIG. 5.

Further, the adjuster 27 is connected via a control rod 30 to a row rear actuator 31 attached to the upper end of the reservoir chamber, and is rotated by drive control of the row rear actuator 31. That is, the opening at the upper end of the casing 31a housing the low reactor actuator 31 is fitted into the opening at the lower surface of the upper lid member 11c at the upper end of the reservoir chamber.
The upper end of the support rod 12 is fitted into and connected to the opening at the lower end of the support rod 1a, and the upper end of the control rod 30 is connected to the drive shaft 31b of the rotary actuator 31 through the through hole 12a of the support rod 12. has been done. The harness 31c of the low reactor 31 is connected to the hollow part 11 of the mounting part lie of the upper lid member 11c.
It is derived to the outside via the inside of f.

Note that 32 is a sealing member.

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 communicated with each other. That is, as shown in the circuit diagram of FIG. 6, the upper chamber A and the reservoir chamber are connected to the first
The first communication passage (3), which includes the communication hole 22a, the intermediate chamber E, the second communication hole 16e, and the upper annular groove 16a, communicates with each other via the first damping valve 21 and the second damping valve 15 on the way. At the same time, they are communicated with each other by a bypass channel II that includes the through hole 12a, the hollow portion 27C1, and the upper port 12b.

Further, the upper chamber A and the lower chamber B are connected to the first communication hole 22a, the intermediate chamber E,
The base communication path 22c is a component of the second communication path (2), and the through hole 12a and the hollow portion 27C communicate with each other.
1 lower bow)-120, communication groove 16f, upper annular groove 16
a, second communication hole 16e, intermediate chamber E, base communication path 22c
They are communicated by a bypass flow path (■) consisting of a component.

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 is transferred to the guide member 2.
flows into the outer chamber C via the lower communication passage 2d, and further,
From this outer chamber C, it passes through a second communication path III to reach the first communication path I, and from there, it proceeds through the first communication path I and opens the second damping valve 15 to flow into the reservoir chamber, or Alternatively, it flows from the bypass flow path (2) further into the upper chamber A via the bypass flow path II.

Therefore, when the lower orifice hole 27b is able to flow, a damping force is generated in the second damping valve 15 and the lower orifice hole 27b, and in this case, the characteristics are in the low damping force range.

On the other hand, if the lower boat 12c is closed based on the rotation of the adjuster 27, the characteristics of only the second damping valve 15 will become the characteristics of the high damping force range.

Furthermore, an amount of fluid corresponding to the volume of the piston rod 6 that has withdrawn from the cylinder tube 1 is supplied to the upper chamber A from the reservoir chamber via the first check passage 22b. Therefore, even if the damping force characteristics on the rebound side are set high, the upper chamber A
There is no negative pressure (no cavitation occurs).

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 pressure side stroke During the pressure side stroke, the volume of the lower chamber B is expanded and the upper chamber A
is reduced.

According to this volume change, the fluid in the upper chamber A flows to the reservoir chamber or the outer chamber C on the low pressure side.

That is, the fluid flow path in the upper chamber A in this case is as follows:
There are four types: ■■■■ below.

(2) A path that passes through the bypass channel II and flows into the reservoir chamber via the upper orifice hole 27a.

■ It flows from the middle of the bypass flow path II to the bypass flow path ■ side and flows into the intermediate chamber E via the lower orifice hole 27b.
Furthermore, a path flows into the outer chamber C through the second communication path (2) via the base communication path 22c.

■ A path that passes through the second communication path ■■ and opens the first damping valve 21 to flow into the outer chamber C.

- A path that proceeds through the first communication path I, opens both damping valves 21.15, and flows into the reservoir chamber.

Therefore, when the two orifice holes 27a and 27b are able to flow, the fluid passes through the flow paths from ■ to ■, and the first damping valve 2
A damping force is generated in the first and both orifice holes 27a and 27b, and in this case, the damping force is a characteristic in the low damping force range.

Furthermore, when both orifice holes 27a and 27b are closed, the fluid passes through (1) and (2), and damping force is generated at both damping valves (5) and (21), and in this case, the characteristics are in the high damping force range.

Furthermore, when the pressure in the outer chamber C and the lower chamber B becomes negative, fluid is supplied from the reservoir chamber through the second check flow path 16d, so that the lower chamber B becomes a negative pressure. No cavitation occurs.

Therefore, even in the case of an overwhelming 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.

(c) When assembling the vehicle body When the shock absorber of this embodiment is assembled to the vehicle body, the low reactor actuator 31 is also assembled at the same time.

Therefore, the assembly is easy, and since the position relative to the vehicle body is determined at the same time, one positioning is easy and the assembly accuracy can be easily maintained at a high level.

Furthermore, since there is no need to provide a mounting space for the row reactuator 31 in the vehicle body, the present invention has a feature that the degree of freedom in mounting the low reactor 31 on the vehicle is high.

The position of the low reactuator 31 with respect to the shock absorber is determined at the time of assembly to the shock absorber, and this structure is a structure in which it is attached by fitting and is attached without intervening a bracket or the like. Therefore, even if the mounting part 11e is screwed into the vehicle body,
The position of this row reactuator 31 does not change.

Therefore, it has the feature of being able to maintain high positional accuracy.

In addition, since the outer tube 11 is supported by the strut tube 7, it has extremely high support rigidity, and is particularly strong against lateral loads, making it ideal for vehicle suspensions. ing.

Next, a second embodiment shown in FIG. 7 will be described. still,
In describing this embodiment, the same components as in the first embodiment 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 like the first embodiment.

That is, in FIG. 7, 200 is a spool, and an upper annular groove 201 and a lower annular groove 202 are formed on the outer periphery.

The two annular rings 201 and 202 are respectively connected to the communication hole 2.
03.204 communicates with the hollow part 205.

Therefore, by sliding the spool 200 up and down, the flow path between the ports 12b, 12c and the hollow portion 205 can be arbitrarily changed from a completely closed state to a fully open state. Note that FIG. 9 shows the fully open state.

That is, it is possible to change the damping force range to any range from a low damping force range to a high damping force range.

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 may also be configured without strut tubes or springs.

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.

In addition, in the embodiment, the variable orifice is the first. The variable orifice is provided in a bypass passage parallel to the second communication passage, and the fluid flow rate in both communication passages is changed by adjusting the fluid flow rate in this bypass passage.This variable orifice is provided in both communication passages. It may also be configured to directly change the flow rate of this communication path.

(Effects of the Invention) As explained above, in the variable damping force type hydraulic shock absorber of the present invention, due to the above-described configuration, cavitation does not occur in both the upper and lower chambers, and the damping force range can be varied. In addition, since the actuator is assembled between the upper end mount of the shock absorber's outer tube and the base before attaching the shock absorber to the vehicle body, it is easy to assemble. The mounting accuracy is high, and the degree of freedom of mounting on the vehicle is high.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the entirety of the buffer according to the first embodiment of the present invention;
2 and 3 are cross-sectional views showing the main parts of the first embodiment, FIG. 4 is a cross-sectional view taken along the line rV-IV in FIG. 3, and FIG.
(2) Cross-sectional view, FIG. 6 is a circuit diagram showing the fluid flow path of the first embodiment, and FIG. 7 is a cross-sectional view showing essential parts of the second embodiment of the present invention. ■... Cylinder tube 2... Guide member 2a -... Rod insertion port 2 d -... Lower communication path 3... Base 5... Piston 6... Piston rod 11... Outer tube 11e ...Mounting part 27...Adjustor (variable orifice) 31...Rotary actuator (actuator) ■...First communication path■...Second communication path A...Upper chamber B... Lower chamber C... Outer chamber D... Reservoir chamber

Claims (1)

[Scope of Claims] 1) A cylinder tube having 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 being defined into an upper chamber and a lower chamber; A piston is connected to a piston rod inserted into a cylinder tube, and an outer chamber is formed surrounding the cylinder tube and communicates with a 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; a first communication passage formed in the base and communicating the upper chamber and the reservoir chamber; and a first communication passage communicating the upper chamber and the outer chamber. a second communication passage communicating the reservoir chamber with the upper chamber; a variable orifice provided in the base so as to be able to change the fluid flow rate of both communication passages; and an upper end attachment portion of the outer tube and the base. A variable damping force hydraulic shock absorber, comprising: an actuator that is provided between the two and operates a variable orifice;