JPH0361736A - Damping force-variable hydraulic damper - Google Patents

Abstract

PURPOSE:To change the damping force in both expansion and compression strokes by providing the first through third variable orifices on the first bypass passage. CONSTITUTION:In the expansion stroke, the volume of a lower chamber (b) is shrunk, the volume of an upper chamber (a) is expanded, the fluid in the chamber (b) flows into an outside chamber (c) via a lower passage (e) according to this volume change, and it flows from there into the upper chamber (a) and a reservoir chamber (d). Damping forces are generated at the second damping valve (h) and the first through third variable orifices (r), (s) and (t) in the flowing passage of the fluid. The flows on the valve (h) side and orifices (r), (s) and (t) are changed in response to aperture changes of variable orifices (r), (s) and (t), and the range of the damping force is changed. When orifices (r), (s) and (t) are throttled, a high-damping force range is obtained, when they are opened, a low-damping force range is obtained. In the compression stroke, the fluid in the chamber (a) flows into the chamber (b) and chamber (d), damping forces are generated at the first damping valve (g) and orifices (r), (s) and (t) in the flowing passage, and the same phenomenon as the expansion stroke occurs.

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. This relates to an inverted type Q-type device 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 has a structure in which an overwhelming damping valve is provided in 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 fluid is not supplied directly to the lower chamber from the reservoir chamber but via the upper chamber, during the overwhelming stroke, if the piston hole restricts the fluid flow rate from the upper chamber to the lower chamber too much, , the amount of fluid supplied to the lower chamber is insufficient, resulting in negative pressure and cavitation. For this reason,
It is not possible to set the compression side damping force high.

The present invention was made with attention to such problems, and
A damping force that allows the damping force to be varied in both the rebound and compression strokes, widens the variable range of the damping force on both the rebound and overwhelming strokes, and provides a large degree of freedom in setting the damping force. The purpose of this project is to provide a variable hydraulic shock absorber.

(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; a first damping valve communicating the upper chamber with the reservoir chamber via a first damping valve and a second damping valve disposed in series;
a communication passage, a second communication passage communicating between the two damping valves in the first communication passage and the outer chamber; a first bypass passage communicating between the upper chamber and the reservoir chamber in parallel with the two damping valves; a second bypass passage communicating with the first bypass passage; a first check passage communicating the reservoir chamber with the upper chamber; and a second check passage communicating the reservoir chamber with the outer chamber; a first variable orifice provided closer to the reservoir chamber than the communication position with the second bypass path, a second variable orifice provided closer to the upper chamber side, and a third variable orifice provided in the second bypass path; has been established.

(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 a first communication passage; g is a first damping valve; h is a second damping valve; j is a second communication passage; k is a first bypass passage;
m is the second bypass path, n is the first check flow path, p is the second
In the check channel, r is the first variable orifice, S is the second variable orifice, and t is the third variable orifice.

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.
The fluid flows into the outer chamber C through the outer chamber C, and from there into the upper chamber a and the reservoir chamber. In this case, the following three paths can be taken as the fluid distribution path.

That is, the first path passes through the second communication path j of the base,
This is a path in which it flows into a position between both damping valves g and h of the first communication passage f, and from there flows into the reservoir chamber d via the first communication passage f and the second damping valve h.

The second path is a path from the second communication path j through the second bypass path m, through the third variable orifice t, and further from the first bypass path through the first variable orifice r to flow into the reservoir chamber d. be.

The third path is a path in which the fluid flows to the first bypass path k in the same manner as the second path, and from there flows into the upper chamber a via the second variable orifice S.

Therefore, a damping force is generated in the 2211i damping valve h and each variable orifice r, s, t.

In this case, depending on the aperture change of each variable orifice r, s, t, the second damping valve h side (first path) and each variable orifice r, s, side (second and third path) are connected. The flow rate changes and the damping force range changes. That is, when the variable orifices r, s, and t are narrowed, a high damping force range is obtained, and when they are opened, a low damping force range is obtained.

Note that an amount of fluid corresponding to the volume of the piston rod that has exited from the cylinder tube enters the upper chamber a.
It is supplied from the reservoir chamber d via the check channel n.

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 flows into the lower chamber and the reservoir chamber d. In this case, the following three paths can be taken as the fluid circulation path.

That is, the first path passes through the first communication path f, passes through the first damping valve g, and reaches a position between the two damping valves g and h, and further,
From this position, it flows into the outer chamber C through the second communication path j,
Furthermore, it is a route from the lower communication passage e to the lower chamber.

The second path is a path that flows into the reservoir chamber d via the second variable orifice S and the first variable orifice r in the first bypass path.

The third path passes through the second variable orifice t in the first bypass path, passes through the second bypass path m, passes through the third variable orifice S, and reaches a position between the two damping valves g and h, and from this position the second variable orifice t. It flows into the outer chamber C through the two-way communication path j, and further extends from the lower communication path e to the lower chamber I.

Therefore, the first damping valve g and each variable orifice r, s
, t, a damping force occurs.

In this case, depending on the aperture change of each variable orifice r, s, t, the first damping valve g side (first path) and each variable orifice r, s, side (second and third path) are connected. The flow rate changes and the damping force range changes. That is, when the variable orifices r, s, and t are narrowed, a high damping force range is obtained, and when they are opened, a low damping force range is obtained.

In the case of this pressure side stroke, the fluid in the upper chamber a is supplied to the lower liquid chamber as described above, and furthermore, the fluid in the reservoir chamber is supplied through the second check flow path. First damping valve g and each variable orifice r, s, t
Even if the characteristics are set to high damping force characteristics, the lower chamber does 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 l in the figure represents 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. 3, 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 20 is provided. 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. 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 an overwhelming damping valve 5a and an extension damping valve 5b, so that a damping force is generated when the valves open depending on the stroke direction (see FIG. 3). 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 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 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. 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 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 an upper annular groove 22d formed on its upper surface (see FIG. 7), a first communication hole 22a that communicates the upper chamber A with the intermediate chamber E, and a first communication hole 22a that communicates the upper chamber A with the intermediate chamber E, and connects the reservoir chamber with the upper chamber. A first check passage 22b that communicates with A, and a base communication passage 22c that communicates between the intermediate chamber E and the outer chamber C are formed. The first communication hole 22a is narrowed by the first damping valve 21, and the first check flow path 22b is narrowed by the first check valve 23 so that only flow from the reservoir chamber to the upper chamber A is allowed. It has become.

Next, in the second body 16, an upper annular groove 16a is formed on the upper surface (see FIG. 6), 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. A second check flow path 16d that communicates the reservoir chamber with the intermediate chamber E is opened in the outer annular groove 16c.
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.

Note that 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 1.2a that opens into the upper chamber A at its axial center, and a first boat 12b that communicates with the reservoir chamber in the radial direction through a communication groove 16f. a second boat 12C communicating with the upper annular groove 16a;
The third groove communicates with the lower annular groove 22d via the communication groove 22e.
A boat 12d is formed.

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 bushing 29.

This adjuster 27 has a first port corresponding to the first port 12b.
An orifice hole 27a, a third orifice hole 27b matching the second port 12C, and a second orifice hole 27c matching the third port 12d are formed.

In addition, FIG. 5 is a V-V sectional view of FIG. 4, and FIG. 6 is a cross-sectional view of FIG. 4.
The Vl-Vl cross-sectional view in the figure, and FIG. 7 is the ■-■ cross-sectional view in FIG.
The port 12C and the third port 12d are formed in two locations facing each other, and the upper annular groove 16a and the second port 12
A communication groove 16f that communicates with the third port 12d and a communication groove 22e that communicates the upper annular groove 22d with the third port 12d are also formed at two corresponding locations.

A first orifice hole 27a communicates between the first boat 12b and the hollow section 27c, and a first orifice hole 27a communicates between the first boat 12b and the hollow section 27c.
The third orifice hole 27b communicates with the third port 12d, and the second orifice hole 2 communicates the third port 12d with the hollow part 27c.
7c are also formed to face each other, and three sets of each are formed. Note that the cross-sectional views in FIGS. 1 and 4 show the state of cutting corresponding to the IV-rV line in FIGS. 5 to 7, respectively.

Further, as shown in FIGS. 5 to 7, the first orifice holes 27a have α, β, γ,
The third orifice hole 27b is formed on the three axes of the α, γ, and δ axes among the five axes of δ and ε, and the third orifice hole 27b is formed on the three axes of the α, β, and δ axes. The second orifice hole 27c is formed on three axes: an α axis, a β axis, and a γ axis. Note that FIGS. 5 to 7 show a state in which the α-axes of the orifice holes 27a, 27b, and 27c are aligned with the ports 12b, 12c, and 12d.

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 the motor actuator 31. This rotation switches the opening and closing positions of the third orifice hole 27b and the second orifice hole 27c. 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.
The chambers A, C, and D are in communication with each other, that is, as shown in FIG.
, intermediate chamber E.

Inner annular groove 16b, second communication hole 16e, upper annular groove 16
a constitutes the first communication path I in the claims.

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

In addition, the first communication hole 22a, the upper annular groove 22d9, the communication groove 2
2e, third port 12d, hollow part 27d.

The first port 12b constitutes a first bypass path (2) in the claims.

In addition, the communication groove 16f, the second port 12C1 hollow part 27d
This constitutes the second bypass path (2) in the claims.

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

Further, the second check flow path 16d including the second check valve 17 and the outer annular groove 16C1 intermediate chamber E.

The base communication passage 22c constitutes a second check passage (2) in the claims.

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 1
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.
It flows into the outer chamber C through the lower communication passage 2d, and from there into the upper chamber A and the reservoir chamber, and can take the following three routes at that time.

That is, the first path passes through the second communication path II to the intermediate chamber E.
This is a path in which the liquid flows into the reservoir chamber through the first communication path I, the second damping valve h, and the second damping valve h.

The second path is similar to the first path, passes through the second bypass path ■ without passing through the second damping valve 15, passes through the third orifice hole 27b, flows into the first bypass path ■, and from there. , which is a path that flows into the reservoir chamber via the first orifice hole 27a.

The third path is a path in which, like the second path, the liquid flows into the first bypass path III and then flows into the upper chamber A via the second orifice hole 27c.

Therefore, the second damping valve 15 and each orifice hole 27a,
Damping forces may be generated at 27b, 27c.

Incidentally, an amount of fluid corresponding to the volume of the piston rod 6 that has exited from the cylinder tube I is supplied to the upper chamber A from the reservoir chamber via the first check flow path V. 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 pressure side 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 lower chamber B (
It flows into the outer chamber C) and into the reservoir chamber, and can take the following three routes.

That is, the first path is a path that passes through the first communication path I, passes through the first attenuation pulp 21, and then flows into the outer chamber C through the second communication path ■, and the second path is the path that flows through the first bypass This is the route through which the water passes through the path (I) and flows into the reservoir chamber via the first and second orifice holes 27a and 27c.

The third path passes through the first bypass path III, the second orifice hole 27c, the second bypass path ■, the third orifice hole 27b, and then the second communication path II to the outer chamber C. This is the route of inflow.

Therefore, the first damping valve 21 and each orifice hole 27a
, 27b, 27c can generate a damping force.

As described above, the fluid in the upper chamber A is supplied to the lower chamber B, and the fluid in the reservoir chamber is further supplied to the lower chamber B via the second check flow path (2). There is no negative pressure and 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.

Note that during this overwhelming stroke, the compression side damping valve 5a opens even in the piston 5, and a damping force is generated.

Further, in this embodiment, there are five rotational positions of the adjuster 27 as shown in the following diagram. In addition, α in the same chart.

β, γ, δ, and ε are each orifice hole 27a in FIGS.
, 27b, and 27c, and this axis corresponds to each boat 12b, 12c, and 12d. Also, the X mark indicates a state in which the orifice hole does not communicate, and the ○ mark indicates a state in which the orifice hole is connected. Each state of communication is shown.

In other words, in the α position, both the extension side and compression side are 5 as shown in Figure 9.
OFT damping force, in the β position, as shown in Figure 10, the damping force is 5OFT on the rebound side and MEDIUM on the compression side, in the γ position, as shown in Figure 11, the damping force is HARD on the rebound side and 5OFT on the compression side, and in the δ position, the damping force is HARD on the rebound side and 5OFT on the compression side. As shown in Figure 13, the damping force is 5OFT on the rebound side and HARD on the compression side, ε
In the position, as shown in FIG. 13, the damping force is HARD on both the expansion side and the compression side.

Incidentally, FIGS. 5 to 7 show the state of the α position.

As described above, the first embodiment has the feature that the range can be switched to many damping force characteristics.

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 of being

Next, a second embodiment shown in FIG. 14 will be described. 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. 14, 200 is a spool constituting a variable orifice, and has a first i-shaped groove 201 and a second i-shaped groove on its outer periphery.
An annular groove 202 and a third annular groove 203 are formed.

Each of the annular grooves 201 and 203 is connected to the communication hole 2, respectively.
04.205.206 communicate with the hollow part 207.

Therefore, by sliding the spool 200 up and down, the two positions of the α position and the ε position in the first embodiment can be adjusted.
The damping force characteristics can be switched between two positions.

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 this embodiment. For example, in the embodiment, a strut type 6 was shown,
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.

(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. Furthermore, by providing three variable orifices, the degree of freedom in setting the damping force can be greatly increased.

In addition, cavitation does not occur in both the rebound and overpowering strokes, 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 5 is a sectional view taken along the line V-V in FIG. 4, FIG. 6 is a sectional view taken along Vl-Vl in FIG. 4, and FIG. -■ sectional view, FIG. 8 is a circuit diagram showing the fluid flow path of the second embodiment, FIGS. 9 to 13 are damping force characteristic diagrams with respect to piston speed of the first embodiment, and FIG. FIG. 2 is a cross-sectional view showing the main parts of the second embodiment. l...Cylinder tube 2...Guide member 2a...Rod insertion port 2d...Lower communication passage 3...Base 5...Piston 6...Piston rod 15...Second damping valve 21... First damping valve 27a... First orifice hole (first variable orifice) 27b... Second orifice hole (second variable orifice) 27c... Third orifice hole (third variable orifice) A... Upper chamber B... Lower chamber C... Outer chamber D-... Reservoir chamber ■... First communicating path II... Second communicating path III... First bypass path ■... ...Second bypass path V...First check flow path■...Second check flow path (second bypass 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. A first communication passage, a second communication passage that communicates between the damping valves in the first communication passage and the outer chamber, a first bypass passage that communicates the upper chamber and the reservoir chamber in parallel with both damping valves, and a first bypass passage that communicates between the two damping valves and the outer chamber; a second bypass passage communicating the position and the first bypass passage; a first check passage communicating the reservoir chamber with the upper chamber; and
a second check flow path that communicates the reservoir chamber with the outer chamber; a first variable orifice provided in the first bypass path closer to the reservoir chamber than the communication position with the second bypass path; and a first variable orifice provided in the upper chamber side. A variable damping force hydraulic shock absorber comprising: a second variable orifice; and a third variable orifice provided in the second bypass path.