JP2832045B2 - Variable damping force type hydraulic shock absorber - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a variable damping force type hydraulic shock absorber applied to a vehicle suspension, and more particularly, to a piston rod side connected to an axle and a cylinder tube side used to a vehicle body. To an inverted type connected to a computer.

2. Description of the Related Art Conventionally, an inverted damping force variable type hydraulic shock absorber described in, for example, Japanese Patent Application Laid-Open No. 58-97334 is known.

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

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

It is a structure that makes the damping force variable only during the compression side stroke,
The damping force cannot be changed during the extension stroke.

Since the lower chamber has a structure in which the fluid is not directly supplied from the reservoir chamber but is supplied through the upper chamber, if the fluid flow from the upper chamber to the lower chamber is excessively restricted by the piston hole during the compression stroke, Insufficient fluid supply to the lower chamber, resulting in negative pressure and cavitation. For this reason, the compression side damping force cannot be set high.

The present invention has been made in view of such a problem, and it is possible to make the damping force variable in both the stretching side and the compression side stroke, and to widen the variable width of both the stretching side and the compression side damping force. It is another object of the present invention to provide a variable damping force type hydraulic shock absorber having a large degree of freedom in setting a damping force.

(Means for Solving the Problems) In order to achieve the above object, in the variable damping force type hydraulic shock absorber of the present invention, a guide member having a rod insertion port is provided at a lower end, and a base is provided at an upper end. A cylinder tube,
The cylinder tube is defined in an upper chamber and a lower chamber, and a piston connected to a piston rod inserted into the cylinder tube from a rod insertion port is provided, and a lower communication passage is provided around the cylinder tube, and is provided around the cylinder tube. An outer tube communicating with the lower chamber through the outer tube, and an outer tube forming a reservoir chamber defined by the base as the outer chamber and the upper chamber above the cylinder tube; and an upper chamber formed in the base and connected in series to the upper chamber. A first communication passage communicating with the reservoir chamber via the first damping valve and the second damping valve arranged, a second communication passage communicating the position between both damping valves of the first communication passage and the outside chamber, and both damping valves; A first bypass path communicating the upper chamber and the reservoir chamber in parallel, a second bypass path communicating the position between both valves and the first bypass path, and the reservoir chamber as the upper chamber A first check passage that passes therethrough, a second check passage that communicates the reservoir chamber with the outer chamber, and a first check passage that is provided closer to the reservoir chamber than a communication position with the second bypass passage in the first bypass passage. A variable orifice and a second variable orifice provided on the upper chamber side;
A third variable orifice provided in the bypass passage.

(Operation) The operation of the variable damping force type hydraulic shock absorber of the present invention will be described with reference to the fluid circuit diagram of FIG. FIG. 1 shows a flow path of a fluid 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 The first communication passage, g is the first damping valve, h is the second damping valve, j is the second communication passage, k is the first bypass passage, m is the second bypass passage, n is the first check passage, and p is the first check passage. The second check channel, r is the first variable orifice, s is the second
The variable orifice, t, is a third variable orifice.

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

In accordance with this volume change, the fluid in the lower chamber b flows into the outer chamber c via the lower communication passage e, and then flows into the upper chamber a and the reservoir chamber. The following three paths can be taken.

That is, the first path flows through the second communication path j of the base to the position between the two damping valves g and h of the first communication path f,
From there, it is a path that flows into the reservoir chamber d through the first communication path f, through the second damping valve h, and then.

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

The third path is a path that flows into the first bypass path k in the same manner as the second path, and then flows into the upper chamber a via the second variable orifice s.

Therefore, the second damping valve h and the variable orifices r, s,
A damping force occurs at t.

In this case, the second damping valve h side (first path) and each variable orifice r, s, t side (second and third paths) are changed according to a change in the throttle of each variable orifice r, s, t. The flow rate changes,
The range of the damping force changes. That is, each variable orifice r,
If s and t are narrowed down, a high damping force range is obtained, and if opened, a low damping force range is obtained.

The upper chamber a is supplied with an amount of fluid corresponding to the volume of the piston rod retreated from the cylinder tube from the reservoir chamber d via the first check channel n of the base.

Therefore, the upper chamber a does not have a negative pressure and cavitation does not occur.

Next, at the time of the compression side stroke, in the cylinder tube,
The volume of the lower chamber b is increased, and the upper chamber a is reduced.

According to this volume change, the fluid in the upper chamber a
And flows into the reservoir chamber d. In this case, the following three paths can be taken as the fluid flow paths.

That is, the first path passes through the first communication path f, passes through the first damping valve g, reaches the 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 passage j,
Further, it is a path from the lower communication passage e to the lower chamber b.

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 of the first bypass path k.

The third path passes through the second variable orifice t of the first bypass path k, 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. This is a path that flows into the outer chamber c through the two communication paths j and further reaches the lower chamber b from the lower communication path e.

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

In this case, the first damping valve g side (first path) and each variable orifice r, s, t side (second and third paths) are changed according to a change in the throttle of each variable orifice r, s, t. The flow rate changes,
The range of the damping force changes. That is, each variable orifice r,
If s and t are narrowed down, a high damping force range is obtained, and if 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 b as described above, and further,
Since the fluid in the reservoir chamber is supplied by the second check flow path, even if the characteristics of the first damping valve g and each of the variable orifices r, s, t are set to the high damping force characteristics, the lower chamber b may have a negative pressure. And no cavitation occurs.

(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 described.

FIG. 2 is a cross-sectional view showing a variable damping force type hydraulic shock absorber according to a first embodiment of the present invention, wherein 1 is a cylinder tube.

The cylinder tube 1 has a tubular shape, a guide member 2 is provided at a lower end portion, a base 3 is provided at an upper end portion, and the inside is filled with a fluid such as oil.

The guide member 2 has a rod insertion port 2a as shown in an enlarged view of a main part in FIG.
2a is provided with a pressure reducing seal 2b, and a stopper rubber is provided.
2c is provided. A seal member 4 having an oil seal 4a is fitted and fixed to the outer periphery of the guide member 2.

Returning to FIG. 2 and continuing the description, a piston 5 is slidably provided in the cylinder tube 1 so that the cylinder 1
Are defined as an upper chamber A and a lower chamber B.

The piston 5 is provided with a compression-side damping valve 5a and an extension-side damping valve 5b, which open according to the stroke direction to generate a damping force (see FIG. 3). still,
5c is a compression side communication passage, and 5d is an extension side communication passage.

The piston 5 is fastened by a nut 6a to a tip of a piston rod 6 inserted into the cylinder tube 1 from the rod insertion port 2a. The piston rod 6 has a lower end fastened to a bottom cap 7a of the strut tube 7 by a nut 7b.

The strut tube 7 has a lower end fitted and fixed to the nut spindle 8 and a spring seat 9 supporting the lower end of a spring (not shown) at the upper end.
Is provided. At the bottom of the strut tube 7, a bound stopper 10 is provided.

An outer tube 11 is provided on the outer periphery of the cylinder tube 1 so as to extend above the cylinder tube 1. In the outer tube 11, an inner periphery of a lower end portion is fitted to the seal member 4, an inner periphery of an upper portion of an intermediate portion is fitted to the base 3, and an upper end portion is attached to the vehicle body. Can be The outer tube 11 is provided to be vertically slidable relative to the strut tube 7 via two upper and lower bearings 11a and 11b.

The outer tube 11 forms an outer chamber C on the outer periphery of the cylinder tube 1 through the lower communication passage 2d formed in the guide member 2 and communicates with the lower chamber B. On the upper side, a reservoir chamber D filled with a desired amount of fluid under the pressure of the sealed gas is formed.

Next, referring to FIG. 4, the structure of the base 3 will be described in detail.

As shown, the base 3 is attached to the support rod 12
Retainer 13, washer 14, second damping valve 15, second body 1
6, Install the second check valve 17, washer 18, retainer 19, washer 20, first damping valve 21, first body 22, first check valve 23, washer 24, and retainer 25 in order, and finally use nut 26. It is configured to be fastened.

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

An upper annular groove 22d is formed on the upper surface of the first body 22 (see FIG. 7), and the upper chamber A is connected to the intermediate chamber E.
And a first communication hole 22a communicating with the upper chamber A
, And a base communication passage 22c that connects the intermediate chamber E and the outer chamber C to each other. The first communication hole 22a is throttled by the first damping valve 21, and the first check channel 22b is allowed to flow only from the reservoir chamber D to the upper chamber A by the first check valve 23. 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 two layers. In the outer annular groove 16c, a second check flow path 16d connecting the reservoir chamber D to the intermediate chamber E is opened, and only the flow from the reservoir chamber D to the intermediate chamber E is permitted by the second check valve 17. It has become. Also, the inner annular groove 16b
A second communication hole 16e which connects the intermediate chamber E to the reservoir chamber D is formed between the upper annular groove 16a and the upper annular groove 16a.
Can be opened and closed by the second damping valve 15.

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

The support rod 12 has a through hole 12a formed in the upper chamber A at the axial center thereof, and has a first port 12b communicating with the reservoir chamber D in the radial direction, and an upper annular shape through a communication groove 16f. A second port 12c communicating with the groove 16a and a third port 12d communicating with the lower annular groove 22d via the communication groove 22e are formed.

A cylindrical adjuster 27 having a hollow portion 27d is provided in the through hole 12a so as to be rotatable in the circumferential direction while being supported vertically by thrust bushes 28 and 29. In addition, this through hole
The lower end opening of 12a is closed by a lower thrust bush 29.

The adjuster 27 has a first orifice hole 27a that matches the first port 12b, a third orifice hole 27b that matches the second port 12c, and a second orifice hole 27c that matches the third port 12d. ing.

5 is a sectional view taken along line VV of FIG. 4, FIG. 6 is a sectional view taken along line VI-VI of FIG. 4, and FIG. 7 is a sectional view taken along line VII-VII of FIG. As shown in the figure, the first port 12b, the second port 12c, and the third port 12d are formed at two locations facing each other, and have a communication groove 16f that communicates the upper annular groove 16a with the second port 12c. The communication groove 22e for communicating the upper annular groove 22d and the third port 12d is also formed at two places corresponding to the communication groove 22e.

Then, the first orifice hole 27a communicating the first port 12b and the hollow portion 27c, the third orifice hole 27b communicating the second port 12c with the hollow portion 27c, and the third orifice communicating the third port 12d and the hollow portion 27c. The two orifice holes 27c are also formed to face each other, and three sets of each are formed. The cross-sectional views of FIGS. 1 and 4 show the states cut along lines IV-IV in FIGS. 5 to 7, respectively.

Further, as shown in FIGS. 5 to 7, the first orifice holes 27a have α, β, γ,
Of the five axes of δ and ε, the three orifices 27b are formed on three axes of an α axis, a γ axis and a δ axis, and the third orifice holes 27b are formed on three axes of an α axis, a β axis and a δ axis. The second orifice hole 27c has an α axis and β
It is formed on three axes, the axis and the γ axis. 5 to 7 show a state in which the α-axis of each orifice hole 27a, 27b, 27c is matched with each port 12b, 12c, 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 D (see FIG. 2). This rotation switches the open / close position of the third orifice hole 27b and the second orifice hole 27c. 32 is a seal.

As described above, in the first embodiment of the present invention, the upper chamber A, the outer chamber C, and the reservoir chamber D are defined by the base 3, and each chamber A is formed by the passage formed in the base 3. , C, and D, that is, as shown in FIG. 7, the first communication hole 22a, the upper annular groove 22d, the intermediate chamber
E, the inner annular groove 16b, the second communication hole 16e, and the upper annular groove 16a constitute a first communication passage I in the claims.

The base communication passage 22c constitutes a second communication passage II of the present invention.

Further, the first communication hole 22a, the upper annular groove 22d, the communication hole 22e,
The port 12d, the hollow portion 27d, and the first port 12b constitute a first bypass III in the claims.

In addition, by the communication groove 16f, the second port 12c, and the hollow portion 27d,
It constitutes the second bypass IV in the claims.

In addition, a first check flow path including the first check valve 23
22b constitutes the first check channel V in the claims.

A second check flow path including a second check valve 17
The 16d, the outer annular groove 16c, the intermediate chamber E, and the base communication path 22c constitute a second check flow path VI described in the claims.

Next, the operation of the embodiment will be described with reference to the circuit diagram of FIG.

(A) At the time of the extension side stroke At the time of the extension side stroke, the volume of the lower chamber B in the cylinder tube 1 is reduced, and the upper chamber A is enlarged.

In accordance with this change in volume, the fluid in the lower chamber B flows into the outer chamber C via the lower communication passage 2d of the guide member 2, and then flows into the upper chamber A and the reservoir chamber D. Can go through the following three paths.

That is, the first path passes through the second communication passage II and passes through the intermediate chamber E.
, And further flows through the first communication path I, into the reservoir D via the second damping valve h.

The second path flows from the same path as the first path, without passing through the second damping valve 15, through the second bypass path IV, through the third orifice hole 27b, into the first bypass path III, and from there. This is a path that flows into the reservoir chamber D via the first orifice hole 27a.

The third path is a path that flows into the upper chamber A through the second orifice hole 27c after flowing into the first bypass path III in the same manner as the second path.

Therefore, the second damping valve 15 and each orifice hole 27a, 27b,
A damping force can occur at 27c.

The upper chamber A is supplied with the fluid corresponding to the volume of the piston rod 6 retreated from the cylinder tube 1 from the reservoir chamber D via the first check channel V. Therefore, even if the second damping valve 15 has a high damping force characteristic, the upper chamber A does not become negative pressure and cavitation does not occur.

Therefore, it is possible to make the damping force characteristic at the time of the extension stroke variable, and to have a wide variable width of the damping force characteristic.

During the extension stroke, the extension damping valve 5b of the piston 5 is also opened to generate a damping force.

(B) During the compression stroke During the compression stroke, in the cylinder tube 1, the volume of the lower chamber B is increased, and the volume of the upper chamber A is reduced.

According to this volume change, the fluid in the upper chamber A is changed to the lower chamber B
(The outer chamber C) and the reservoir chamber D, which can pass through the following three paths.

That is, the first path is a path that passes through the first communication path I, passes through the first damping valve 21, and further flows through the second communication path II into the outer chamber C. The second path is a first bypass. This is a path that passes through the path III and flows into the reservoir chamber D via the first and second orifice holes 27a and 27c.

The third path passes through the first bypass path III, passes through the second orifice hole 27c, passes through the second bypass path IV, passes through the third orifice hole 27b, further passes through the second communication path II, and then passes through the outside chamber C. This is the route that flows into.

Therefore, the first damping valve 21 and each orifice hole 27a, 27
A damping force can be generated by b and 27c.

As described above, the fluid in the upper chamber A is supplied to the lower chamber B, and the fluid in the reservoir chamber D is further supplied to the lower chamber B via the second check flow path IV.
Does not become negative pressure and cavitation does not occur.

Therefore, also in the case of the compression stroke, the damping force characteristic can be made variable and the variable width of the damping force characteristic can be widened.

During the compression stroke, the compression-side damping valve 5a is opened 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 table. In the table, α, β, γ, δ, and ε are the fifth
7 correspond to the axes of the orifice holes 27a, 27b, and 27c, and show the case where the axes correspond to the ports 12b, 12c, and 12d, and the X mark indicates that the orifice holes do not communicate with each other. A state and a circle mark indicate a state where the orifice holes communicate with each other.

That is, at the α position, the damping force of the SOFT on both the extension side and the compression side as shown in FIG. 9, at the β position, the damping force of the SOFT and the compression side at the extension side as shown in FIG. As shown in FIG. 13, the expansion side is HARD and the compression side is the damping force of SOFT, in the δ position, as shown in FIG. 13, the expansion side is SOFT and the compression side is the damping force of HARD. The compression side is the damping force of HARD.

5 to 7 show the state of the α position.

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

Further, in the first embodiment, since the outer tube 11 is supported by the strut tube 7, the support tube has extremely high support rigidity, and particularly has high strength against a lateral load, and is most suitable for a vehicle suspension. It has the feature that it is.

Next, a second embodiment shown in FIG. 14 will be described.
In describing this embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and only the differences will be described.

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

That is, in FIG. 14, reference numeral 200 denotes a spool constituting a variable orifice, and a first annular groove 201, a second annular groove 202, and a third annular groove 203 are formed on the outer periphery. Each of the annular grooves 201 and 203 is connected to the hollow portion 207 by the communication holes 204, 205 and 206, respectively.

Therefore, the damping force characteristic can be switched between the α position and the ε position in the first embodiment by sliding the spool 200 up and down.

The embodiments of the present invention have been described in detail with reference to the drawings.
The specific configuration is not limited to this embodiment. For example, although a strut type is shown in the embodiment, a configuration in which a strut tube and a spring are omitted may be employed.

Also, the piston is provided with a damping valve,
The upper chamber and the lower chamber may not be connected at all on the piston side.

(Effect of the Invention) As described above, in the variable damping force type hydraulic shock absorber of the present invention, the damping force is variable in both the compression stroke and the expansion stroke because of the above-described configuration. In addition, by providing three variable orifices, it is possible to obtain an effect that the degree of freedom in setting the damping force can be greatly increased.

Further, there is obtained an effect that cavitation does not occur in both the extension side and the compression side stroke, and the variable width of the damping force range can be widened.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a fluid flow path of a variable damping force type hydraulic shock absorber according to the present invention. FIG. 2 is a cross-sectional view showing the whole shock absorber according to the first embodiment of the present invention. FIG. 5 is a sectional view showing a main part of the first embodiment, FIG. 5 is a sectional view taken along line VV of FIG. 4, FIG. 6 is a sectional view taken along line VI-VI of FIG. 4, and FIG. FIG. 8 is a circuit diagram showing the fluid flow path of the first embodiment, FIG.
FIG. 13 to FIG. 13 are diagrams showing damping force characteristics with respect to the piston speed of the first embodiment, and FIG. 14 is a cross-sectional view showing a main part of the second embodiment of the present invention. 1 ... Cylinder tube 2 ... Guide member 2a ... Rod insertion port 2d ... Lower communication path 3 ... Base 5 ... Piston 6 ... Piston rod 15 ... Second damping valve 21 ... First damping valve 27a ... 1st orifice hole (first variable orifice) 27b ... 2nd orifice hole (2nd variable orifice) 27c ... 3rd orifice hole (3rd variable orifice) A ... upper chamber B ... lower chamber C ... ... Outside chamber D ... Reservoir chamber (second bypass passage) I ... First communication passage II ... Second communication passage III ... First bypass passage IV ... Second bypass passage V ... First check passage VI: Second check channel

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Hiroyuki Shimizu 1370 Onna, Atsugi-shi, Kanagawa Prefecture Inside Atsugi Automotive Parts Co., Ltd. (56) References JP-A-2-285532 (JP, A) JP-A-61- 282636 (JP, A) Japanese Utility Model Showa 62-185941 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) F16F 9/00-9/58

Claims (1)

(57) [Claims] A guide member having a rod insertion port is provided at a lower end, a cylinder tube having a base provided at an upper end, and the cylinder tube is defined in an upper chamber and a lower chamber. A piston connected to the inserted piston rod, and an outer chamber provided around the cylinder tube and communicating with the lower chamber through a lower communication passage on the outer periphery of the cylinder tube, and an outer side formed by a base above the cylinder tube. An outer tube forming a reservoir chamber defined as a chamber and an upper chamber; and a first tube formed in the base and communicating the upper chamber to the reservoir chamber through a first damping valve and a second damping valve arranged in series. A second communication passage which communicates a passage, a position between both damping valves of the first communication passage with the outside chamber, and an upper chamber and a reservoir chamber which are connected in parallel with the two damping valves. That the first bypass passage, both valves between position and a second bypass passage for communicating the first bypass passage, the first check passage communicating the reservoir chamber to the upper chamber, and,
A second check flow path communicating the reservoir chamber with the outer chamber; a first variable orifice provided on the reservoir chamber side of the first bypass path with respect to a communication position with the second bypass path; and a second check flow path provided on the upper chamber side. A variable damping force type hydraulic shock absorber comprising: a second variable orifice; and a third variable orifice provided in the second bypass passage.