JP3079338B2 - Damping force adjustable hydraulic shock absorber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a damping force-adjustable hydraulic shock absorber mounted on a suspension system of a vehicle such as an automobile.

[0002]

2. Description of the Related Art A hydraulic shock absorber mounted on a suspension system of a vehicle such as an automobile is provided with a damping force that can be appropriately adjusted according to road surface conditions, running conditions, and the like in order to improve ride comfort and steering stability. There is a damping force adjustable hydraulic shock absorber.

Conventionally, as this type of hydraulic shock absorber, for example, as disclosed in Japanese Utility Model Application Laid-Open No. 58-70533, a piston having a piston rod connected to a cylinder in which oil is sealed is slid. And the first chamber and the second chamber communicate with each other through a first and second oil passages. The first oil passage has a damping force that generates a relatively large damping force. There is a mechanism in which a generating mechanism (orifice, disk valve, etc.) is provided, and a damping force generating mechanism having relatively small damping force and a damping force adjusting valve for opening and closing the second oil liquid passage are provided in the second oil liquid passage. .

With this configuration, when the damping force adjusting valve is opened, the oil in the cylinder mainly flows through the second oil liquid passage and expands and contracts by sliding of the piston accompanying expansion and contraction of the piston rod. A relatively small damping force is generated, and the damping force characteristic becomes a soft characteristic. When the damping force adjusting valve is closed, the oil in the cylinder flows only through the first oil liquid passage and generates a relatively large damping force on both the expansion and contraction sides due to the sliding of the piston accompanying the expansion and contraction of the piston rod. The damping force characteristics are hard characteristics. Thus, the damping force characteristics can be switched by opening and closing the damping force adjusting valve.

Further, by using a control device and an actuator, the ride comfort and the driving stability are improved by automatically switching the damping force characteristics of the damping force-adjustable hydraulic shock absorber according to the road surface condition, running condition and the like. There is a suspension control device as described above.

In this type of suspension control device, the damping force characteristic of the damping force adjusting type hydraulic shock absorber is set to a hard characteristic when its piston rod strokes toward a predetermined neutral position, and the piston rod strokes away from the neutral position. It has been known that when the soft characteristics are used, bouncing of the vehicle body can be effectively controlled, and riding comfort can be improved.

[0007]

However, when such a bouncing control is performed by using the above-mentioned conventional damping force-adjustable hydraulic shock absorber, the piston rod has an extension such as a hard characteristic on the extension side and a soft characteristic on the contraction side. When different characteristics are required between the compression side and the compression side, the damping force adjustment valve must be opened and closed each time the expansion / contraction stroke direction changes.However, the control device detects the change in the stroke direction of the piston rod and the control device issues a switching signal. Since it usually takes about 15 to 20 msec for the actuator to output and open and close the damping force adjusting valve, it is difficult to perform sufficient control for actual running.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has a different damping force characteristic between the extension side and the contraction side in order to rapidly switch the damping force characteristic with a change in the stroke direction of the piston rod. An object of the present invention is to provide a damping force-adjustable hydraulic shock absorber capable of selecting a combination.

[0009]

In order to solve the above-mentioned problems, a damping force-adjustable hydraulic shock absorber according to a first aspect of the present invention includes a cylinder filled with an oil liquid and a slidable cylinder. A piston fitted and defining the inside of the cylinder into two chambers;
A piston rod having one end connected to the piston and the other end extending to the outside of the cylinder, a main oil passage having a damping force generating mechanism communicating with the two chambers, and bypassing the damping force generating mechanism. A first non-return valve and a second non-return valve provided in series with the bypass passage and permitting flow in opposite directions, and the first non-return valve; A first oil liquid passage that bypasses the second check valve; a second oil liquid passage that bypasses the second check valve;
A first damping force adjusting valve for varying the passage area of the oil fluid passage, and a second damping force regulating valve for varying the passage area of the second oil fluid passage . 2 damping force adjustment
The valve has a passage area of both the first and second oil liquid passages.
Also open, one open and the other closed or one closed and the other open
It is characterized in that it can be selectively adjusted so that

A damping force-adjusting hydraulic shock absorber according to a second aspect of the present invention has a cylinder filled with an oil liquid, and is slidably fitted in the cylinder to define the inside of the cylinder as two chambers. An oil boundary defining member, a rod having one end connected to the oil boundary defining member and the other end extending to the outside of the cylinder; a main oil liquid passage communicating the two chambers; A first damping force generating mechanism provided in the passage for generating damping force, and a second damping force generating mechanism provided in series with the first damping force generating mechanism in the main oil liquid passage and generating damping force. A mechanism and the first
A first bypass passage that bypasses the first damping force generating mechanism, a second bypass passage that bypasses the second damping force generating mechanism, and different directions provided in the first and second bypass passages, respectively. The first to allow the distribution of
A second check valve, a first damping force adjusting valve for varying the passage area of the first bypass passage, and a second damping force adjusting valve for varying the passage area of the second bypass passage Wherein the first and second damping force adjusting valves are provided with the first and second damping force adjusting valves.
Both the passage areas of the second oil liquid passage are open, one is open and the other is
Selectively so that one is closed or one is closed and the other is open
It is characterized by being adjustable .

[0011]

According to the first aspect of the present invention, the first and second damping force adjusting valves adjust the passage areas of the first and second oil liquid passages. In a state where the second oil passage is opened, the bypass passage is communicated through the first and second oil passages, and the oil flows through the main oil passage and the bypass passage in both expansion and contraction strokes. A small damping force is generated. When the passage area is reduced and closed by the first and second damping force adjustment valves, the bypass passage is closed by the first and second check valves and the first and second damping force adjustment valves, In both the expansion and contraction strokes, the oil liquid flows only through the main oil liquid passage, and a relatively large damping force is generated. When one of the first and second damping force adjusting valves is opened and the other is closed, the closed passage check valve allows the passage of the oil liquid in only one direction. In the process of circulating the oil liquid, the oil liquid flows through the main oil liquid passage and the bypass passage to generate a relatively small damping force.In the opposite stroke, the check valve closes the bypass passage and the oil The liquid flows only through the main oil liquid passage to generate a relatively large damping force.

Further, in the second invention, the first and the second
The passage area of the first and second bypass passages is adjusted by the damping force adjusting valve, and when the first and second bypass passages are open, one of the first and second check valves is provided. Are opened in both strokes, and the oil liquid flows between the two chambers through the first bypass passage or the second bypass passage. Therefore, a damping force is generated in one of the first and second damping force generating mechanisms, and a relatively small damping force is generated in both expansion and contraction. When one of the first and second damping force adjusting valves is closed, the first or second bypass passage is opened in one of the expansion and contraction strokes, and the first or second bypass passage is opened.
Alternatively, the damping force is generated by one of the second damping force generating mechanisms to generate a relatively small damping force. In the other stroke of extension or contraction, the first or second bypass passage is closed by the first or second damping force adjusting valve and the first or second check valve, and the first or second damping force is adjusted. A relatively large damping force is generated through both of the generating mechanisms. 1st, 2nd
When both of the damping force adjusting valves are closed, the first and second bypass passages are closed, and a relatively large damping force is generated through both the first and second damping force generating mechanisms in both expansion and contraction strokes. I do.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. A first embodiment will be described with reference to FIGS.

As shown in FIG. 1, in a damping force-adjusting hydraulic shock absorber 1, a piston 3 is slidably fitted in a cylinder 2 in which an oil liquid is sealed. Are defined in two chambers, an upper cylinder chamber 2a and a lower cylinder chamber 2b. The tip of the piston 3 is the cylinder 2
The base end side of a piston rod 4 extending to the outside is penetrated, and a cylindrical passage member 5 is screwed to the base end of the piston rod 4 and connected to the piston 3. In the cylinder 2, the piston rod 4 enters the cylinder 2,
A reservoir chamber (not shown) is provided for compensating entry and exit of the oil liquid corresponding to the exit.

The piston 3 is provided with a main oil liquid passage 6 for communicating the cylinder upper chamber 2a and the cylinder lower chamber 2b.
A first damping force generation mechanism 7 (a damping force generation mechanism) including an orifice and a disk valve that controls the flow of the oil liquid in the main oil liquid passage 6 to generate a damping force is provided on both end surfaces of the piston 3. Power).

The piston rod 4 is provided with an oil liquid passage 8 having one end communicating with the cylinder upper chamber 2a and the other end communicating with the passage member 5 on the cylinder lower chamber 2b side. The passage member 5 forms a bypass passage 9 for communicating the cylinder upper chamber 2a and the cylinder lower chamber 2b.

A valve body 11 having an oil liquid passage 10 communicating with the bypass passage 9 is fitted into an opening of the passage member 5 on the side of the cylinder lower chamber 2b.
A second damping force generating mechanism 12 (small damping force) including an orifice and a disc valve for controlling the flow of the oil liquid in the oil liquid passage 10 to generate a damping force is provided.

In the passage member 5, a cylindrical guide member 13 is provided.
Are fitted. At the end of the guide member 13 on the side of the cylinder upper chamber 2a, a first reverse which allows the flow of the oil liquid from the inside of the guide member 13 to the cylinder upper chamber 2a and prevents the flow of the oil liquid in the opposite direction. A check valve 14 as a stop valve is provided,
A guide member is provided at the end of the guide member 13 on the cylinder lower chamber 2b side.
(13) Allow the oil liquid to flow from the inside to the cylinder lower chamber 2b side,
A check valve 15 is provided as a second check valve for preventing the flow of the oil liquid in the opposite direction.

An oil liquid passage 16 communicating with the cylinder upper chamber 2a and an oil liquid passage 17 communicating with the cylinder lower chamber 2b are formed in the bypass passage 9 between the passage member 5 and the guide member 13. An oil liquid passage is provided on the side wall of the guide member 13.
A hole 18 communicating with the oil passage 16 and a hole 19 communicating with the oil passage 17 are provided, and the oil passage 16 and the hole 18 constitute a first oil passage that bypasses the check valve 14. The passage 17 and the hole 19 constitute a second oil liquid passage that bypasses the check valve 15.

In the guide member 13, a cover-shaped cylindrical shutter 20 as first and second damping force adjusting valves is rotatably fitted. The lid portion of the shutter 20 is provided with an oil liquid passage 21 for communicating the inside of the shutter 20 with the check valve 14 side. A pair of slits 22 are formed in the side wall of the shutter 20, and first and second oil liquid passages are formed depending on whether or not the shutter 20 is rotated to align the slits 22 with the holes 18 and 19 of the guide member 13. Of the first and second oil liquid passages can be opened and closed.

As shown in FIG. 2, the hole 18 of the guide member 13 is
19 is opened from the center of the guide member 13 in directions different from each other. When the shutter 20 is at the position A, the slit 22 and the holes 18 and 19 are aligned, and when the shutter 20 is at the position B, Only the slit 22 and the hole 18 are aligned, and when in the position C, only the slit 22 and the hole 19 are aligned. An operation rod 23 is connected to the bottom of the shutter 20. The operation rod 23 extends through the check valve 14 to the outside along the piston rod 4, and is provided with the damping force adjustable hydraulic shock absorber 1. The shutter 20 can be rotated from outside.

The operation of the first embodiment configured as described above will now be described. The damping force characteristic can be switched by operating the operating rod 23 from outside the damping force adjustable hydraulic shock absorber 1 to rotate the shutter 20.

As shown in FIG. 2, when the shutter 20 is at the position A, the check valve 14 is bypassed by the oil passage 16 and the hole 18 by aligning the hole 18 with the slit 22.
Further, the check valve 15 is bypassed by the oil liquid passage 17 and the hole 19 by aligning the hole 19 with the slit 22. For this reason, since the bypass passage 9 is always communicated, it extends,
During the contraction stroke, the oil in the cylinder 2 is moved by the main oil passage 6 due to the sliding of the piston 3 accompanying the expansion and contraction of the piston rod 4.
The first damping force generating mechanism 7 and the second damping force generating mechanism 12 generate a relatively small damping force through the bypass passage 9. Therefore, the damping force characteristic is represented by A in FIG.
As shown by, soft characteristics are obtained on both the extension side and the contraction side.

When the shutter 20 is at the position B, the hole 18 and the slit 22 are aligned with each other so that the oil passage 16 and the hole 18 are aligned.
The check valve 14 is thereby bypassed. On the other hand, the hole 19 is closed by the shutter 20. For this reason, the bypass passage 9 is communicated via the check valve 15, and allows the flow of the oil liquid from the cylinder upper chamber 2a side to the cylinder lower chamber 2b side. It will block distribution.
Therefore, during the extension stroke of the piston rod 4, the piston 3
The oil in the cylinder 2 flows through the main oil liquid passage 6 and the bypass passage 9 due to the sliding, and the first damping force generating mechanism 7 and the second damping force generating mechanism 12 generate a relatively small damping force. . On the other hand, during the contraction stroke, the flow of the oil liquid in the bypass passage 9 is blocked, so that the oil liquid in the cylinder 2 flows only through the main oil liquid passage 6 due to the sliding of the piston 3 and the first oil liquid flows.
A relatively large damping force is generated by the damping force generating mechanism 7. Accordingly, as shown by B in FIG. 3, the damping force characteristic has a soft characteristic on the extension side and a hard characteristic on the contraction side.

When the shutter 20 is at the position C, the hole 18
It is closed by the shutter 20. On the other hand, hole 19 and slit 22
Is matched, the check valve 15 is bypassed by the oil liquid passage 17 and the hole 19. Therefore, the bypass passage 9
Are communicated through the check valve 14, allowing the flow of the oil liquid from the cylinder lower chamber 2b side to the cylinder upper chamber 2a side, and preventing the flow of the oil liquid in the opposite direction. Become.
Therefore, during the contraction stroke of the piston rod 4, the piston 3
The oil in the cylinder 2 flows through the main oil liquid passage 6 and the bypass passage 9 due to the sliding, and the first damping force generating mechanism 7 and the second damping force generating mechanism 12 generate a relatively small damping force. . On the other hand, during the extension stroke, the flow of the oil liquid in the bypass passage 9 is blocked, so that the oil liquid in the cylinder 2 flows only through the main oil liquid passage 6 due to the sliding of the piston 3 and the first oil liquid flows through the first oil liquid passage.
A relatively large damping force is generated by the damping force generating mechanism 7. Accordingly, as shown by C in FIG. 3, the damping force characteristic has a hard characteristic on the extension side and a soft characteristic on the contraction side.

In this manner, by rotating the shutter 20 to change its position, the damping force characteristic of the damping force adjustable hydraulic shock absorber 1 is changed to the position A: extension side / soft contraction side / soft position B: extension side. / Soft contraction side / hard position C: extension side / hard contraction side / soft Can be selectively switched among three types of combinations. By closing the holes 18 and 19 by the shutter 20 and closing the bypass passage 9, it is possible to expand and contract to provide a hard characteristic on both sides.

In the first embodiment, the second damping force generating mechanism 12 including the orifice and the disk valve is provided. However, the second damping force generating mechanism 12 is not limited thereto. 19 may be an orifice. Also, especially when low damping force (damping force is close to zero) is required,
The fluid resistance in the bypass passage may be used as the second damping force generating mechanism without providing the second damping force generating mechanism. The check valves 14 and 15 of the first embodiment need only be directed in different directions.
May be reversed.

In the above-described first embodiment, the example in which the holes 18 and 19 are opened and closed by the shutter 20 has been described. However, the shutter 20 is stopped at an arbitrary position between the fully opened and fully closed positions of the holes 18 and 19. Hole 1
By adjusting the passage area of the opening formed by the slits 8 and 19 and the slit 22 of the shutter 20, it is possible to generate an arbitrary damping force. In this case, by forming the holes 18 and 19 as odd-shaped holes such as a hole 84 shown in FIG.
The passage area of the opening formed by the holes 18, 19 and the slit 22 of the shutter 20 can be easily and continuously changed,
The orifice characteristics can be changed continuously. Further, the shutter 20 may be provided with an opening of another shape instead of the slit 22.

Next, as a second embodiment, a description will be given of a damping force-adjustable hydraulic shock absorber capable of continuously changing the damping force characteristic. In the present embodiment, since the openings of the guide and the shutter are different from those of the first embodiment, the same members as those of the first embodiment are denoted by the same reference numerals, and only the different parts will be described. This will be described in detail.

As shown in FIG. 4, similar to the first embodiment,
A cylindrical guide member 13a is fitted in the passage member 5. At one end of the guide member 13a, a check valve as a first check valve for allowing the flow of the oil liquid from the inside of the guide member 13a to the cylinder upper chamber 2a side and preventing the flow in the opposite direction is provided. A guide member 13a is provided at the other end.
Check valve as a second check valve that permits the flow of the oil liquid from inside to the cylinder lower chamber 2b side and prevents the flow in the opposite direction
15a is provided.

Between the passage member 5 and the guide member 13a,
In the bypass passage 9, an oil liquid passage 16a communicating with the cylinder upper chamber 2a and an oil liquid passage communicating with the cylinder lower chamber 2b
17a are formed on the side wall of the guide member 13a.
A pair of holes 18a communicating with the oil liquid passage 16a and the oil liquid passage 17
A pair of holes 19a communicating with a are provided. And
The oil passage 16a and the hole 18a constitute a first oil passage that bypasses the check valve 14a, and the oil passage 17 and the hole 19a constitute a check valve.
A second oil liquid passage which bypasses 15a is formed.

In the guide member 13a, a cylindrical shutter 20a is rotatably fitted as first and second damping force adjusting valves. A guide member is provided on the side wall of the shutter 20a.
A pair of openings 22a are provided so as to face the hole 18a of the hole 13a, and a pair of openings 22b are provided so as to face the hole 19a. The openings 22a and 22b are respectively provided with shutters.
Extending along the circumferential direction of 20a, the opening 22a is formed in a substantially wedge shape whose diameter increases toward one side,
The opening 22b is formed in a substantially wedge shape whose diameter increases toward the opposite side. By rotating the shutter 20a, the area of the communication passage formed by the alignment between the hole 18a and the opening 22a changes, and the passage area of the first oil liquid passage is adjusted. Part 22b
The area of the communication passage formed by the adjustment of the second oil liquid passage changes to adjust the passage area of the second oil liquid passage. In this case, when the communication path between the hole 18a and the opening 22a is fully opened, the communication path between the hole 19a and the opening 22b is fully closed, and from this state, as the shutter 20a is rotated to one side, the hole 18a is rotated.
When the communication path between the hole 18a and the opening 22a is fully closed, the area of the communication path between the hole 19a and the opening 22a is large, and the area of the communication path between the hole 19a and the opening 22b is large. The communication passage with is fully opened.

An operation rod 23a is connected to the shutter 20a. The operation rod 23a extends to the outside along the piston rod 4 through the check valve 14a. The shutter 20a can be rotated from outside. The shutter 20a is
The two members 20aA, 20aB and 20aC are joined by an operating rod 23a. In the figure, 23b is a shutter
A bearing that rotatably supports 20a with a small torque,
An oil liquid passage is formed in the inner peripheral portion.

In this embodiment, the cylinder lower chamber of the oil passage 10 is used instead of the second damping force generating mechanism 12 of the first embodiment.
A check valve 12a is provided to allow the flow of the oil liquid from the 2b side to the cylinder upper chamber 2a side.

The operation of the second embodiment configured as described above will now be described. The damping force characteristic can be switched by operating the operation rod 23a from outside to rotate the shutter 20a.

By rotating the shutter 20a, the hole 18a and the opening
When the communication passage with the opening 22a is fully opened and the communication passage with the hole 19a and the opening 22b is fully closed,
In the bypass passage 9, the oil liquid on the cylinder upper chamber 2a side flows through the oil liquid passage 16a, the hole 18a and the opening 22a by closing the check valve 14a, and further opens the check valve 15a to open the oil liquid passage. It flows through 10 to the cylinder lower chamber 2b side. Therefore, hole 18
A small damping force is generated by the passage area between the a and the opening 22a and the damping force generating mechanism 12. On the other hand, during the compression stroke of the piston rod 4, the check valve 15a is closed, and the hole 19a and the opening
Since the communication passage with 22b is closed, the bypass passage 9 is closed. Therefore, the oil liquid flows only through the main oil liquid passage 6 and a large damping force is generated by the damping force generating mechanism 7. Therefore, as shown by A in FIG. 5, the damping force characteristic has a soft characteristic on the extension side and a hard characteristic on the contraction side.

The shutter 20a is rotated from the above position to one side to reduce the area of the communication passage between the hole 18a and the opening 22a,
When the communication passage between the hole 19a and the opening 22b is opened, the oil liquid on the cylinder upper chamber 2a side flows to the cylinder lower chamber 2b side in the bypass passage 9 during the extension stroke of the piston rod in the same manner as described above. The flow and the damping force are increased by the decrease in the area of the communication passage between the hole 18a and the opening 22a (the slope of the valve characteristic is increased). On the other hand, during the contraction stroke of the piston rod 4, in the bypass passage 9, the oil liquid in the cylinder lower chamber 2b side opens the check valve 12a, closes the check valve 15a, and opens the oil liquid passage 17a, the hole 19a and the opening. The air flows through the portion 22b, and further flows to the cylinder upper chamber 2a by opening the check valve 14a. Therefore,
The portion of the hole 19a opened by the opening 22b becomes an orifice, and a small damping force (orifice characteristic) corresponding to the area of the communication passage is generated. Therefore, the damping force characteristic is
As shown by B in FIG. 5, medium characteristics are exhibited on both the extension side and the contraction side.

The shutter 20a is further rotated to one side from the above position, and the communication path between the hole 18a and the opening 22a is fully closed.
When the communication path between the opening 19b and the opening 22b is fully opened, the check valve 14a is closed and the hole 18a is opened during the extension stroke of the piston rod 4.
The bypass passage 9 is closed because the communication passage between the opening 22a and the opening 22a is closed. Therefore, the oil liquid flows only through the main oil liquid passage 6 and a large damping force is generated by the damping force generating mechanism 7. On the other hand, during the contraction stroke of the piston rod 4, the cylinder lower chamber 2b
Oil flows to the cylinder upper chamber 2a side, and the hole 19a and the opening 22
The damping force (orifice characteristic) decreases as the area of the communication passage with b increases. Therefore, the damping force characteristic is
As shown by C in FIG. 5, the elongation side has a hard characteristic,
The contraction side has a soft characteristic.

As described above, different damping force characteristics can be set between the extension side and the contraction side as in the first embodiment.
Further, the hole 18a and the opening are changed according to the rotation angle of the shutter 20a.
Since the communication passage area between the hole 22a, the hole 19a and the opening 22b can be changed continuously, it is possible to continuously adjust the damping force characteristic by changing the passage area of the bypass passage 9 on the extension side and the contraction side. it can. Note that the shutter 20a causes the hole 18
By closing the bypass passage 9 by closing the hole 19a and the hole 19a, it is possible to expand and contract to provide a hard characteristic on both sides.

Next, an example of the bouncing control of the semi-active suspension device using the damping force adjusting type hydraulic shock absorber 1 of the first embodiment will be described.

Neutral ranges N1 and N2 (> N1) are set near the neutral position N of the stroke of the piston rod 4,
The stroke S is detected by the vehicle height sensor, and the control device outputs a switching signal in accordance with the stroke S to operate the actuator to switch the position of the shutter 20. The switching of the shutter 20 is such that when the stroke S is in the neutral range N1, the position is A, when the stroke S is out of the neutral range N2 on the extension side, it is position B, and when it is out of the neutral range N2 on the contraction side, it is position C. Control. The reason for setting the neutral range N2> N1 is to prevent hunting.

According to such control, when a vehicle traveling on a flat road gets over a projection on the road surface, the stroke S of the piston rod 4 is within the neutral range N1 during traveling on a flat road as shown in FIG. , The position of the shutter 20 becomes A,
The damping force characteristics are soft characteristics on both the extension and contraction sides. Times of Day
When the piston rod 4 gets over the projection on the road surface at t1, the piston rod 4 makes a large stroke toward the contraction side, and at time t2, when the stroke S goes out of the neutral range N2 on the contraction side, the position of the shutter 20 is switched from A to C by the control signal, but attenuates. Force characteristics remain soft characteristics. When the stroke S changes from the contraction side to the extension side at time t3, the damping force characteristic automatically becomes the hardware characteristic without a control signal. When the stroke S returns within the neutral range N1 at time t4, the position of the shutter 20 is switched from C to A by the control signal, and the damping force characteristic becomes a soft characteristic. When the stroke S deviates from the neutral range N2 on the extension side at time t5, the position of the shutter 20 is switched from A to B by the control signal, but the damping force characteristic remains the soft characteristic. When the stroke S changes from the extension side to the contraction side at time t6, the damping force characteristic automatically becomes the hardware characteristic without a control signal. When the stroke S returns within the neutral range N1 at time t7, the position of the shutter 20 is set to B by the control signal.
From A to A, and the damping force characteristic becomes a soft characteristic. In this way, bouncing of the vehicle body is suppressed.

At this time, the switching of the damping force characteristic by the control signal based on the detection of the vehicle height sensor may be performed only when the stroke S passes through the neutral range N1 or N2 (time t2, t4, t5, t7). When changing from the contraction side to the extension side (time t3) and from the extension side to the contraction side (time t6), the switching is automatically performed instantaneously without a control signal. Therefore, the frequency of switching of the damping force characteristic by the control signal is reduced, so that the response delay of the control device is small and sufficiently appropriate control can be performed.

Next, a third embodiment of the present invention will be described. In the third embodiment, the same or corresponding members as those in the first embodiment are denoted by the same reference numerals, and only different portions will be described in detail.

As shown in FIG. 7, a small-diameter passage member 24 penetrates through the piston 3, and a passage member 5 is fixedly screwed to a distal end portion thereof. The piston rod 4 is connected to the rear end of the small-diameter passage member 24. An oil liquid passage 25 is formed in the piston rod 4 such that one end thereof communicates with the inside of the small-diameter passage member 24 and the other end opens into the cylinder upper chamber 2a.
Then, the passage member 5, the small diameter passage member 24 and the oil liquid passage 25
This forms a bypass passage 9 that connects the cylinder upper chamber 2a and the cylinder lower chamber 2b.

A cylindrical guide member 26 is fitted in the oil liquid passage 25 of the piston rod 4, and an oil liquid communicated with the outer peripheral portion of the guide member 26 in the bypass passage 9 to the cylinder upper chamber 2 a side. An oil liquid passage 28 communicating with the passage 27 and the cylinder lower chamber 2b side is formed. Holes 29a and 30a are provided on the side walls near both ends of the guide member 26, respectively.
The first check valve 30a and the plate-like spring members 29b and 30b closing the guide member 26 from the outside of the guide member 26 allow the oil liquid to flow from the inside of the guide member 26 to the oil liquid passages 27 and 28. Check valve
A check valve 29 as a second check valve is configured. A hole 31 communicating with the oil liquid passage 27 and a hole 32 communicating with the oil liquid passage 28 are provided on a side wall near the center of the guide member 26. A cylindrical shutter 33 is slidably fitted to the guide member 26. The shutter 33 is large diameter portion 33a is formed to be in sliding contact with the inner wall of the guide member 26 at both ends, so that the valve chamber 33b is formed between the shutter 33 and the guide member 26. The shutter 34 is provided with a through hole 33c in the axial direction thereof, and the chambers at both ends of the shutter 33 in the guide member 26 communicate with the valve chamber 33b by the through hole 33c.

When the shutter 33 is at the neutral position A shown in FIG. 7, the holes 31, 32 and the valve chamber 33b communicate with each other, and the oil liquid passage 27, the hole 31, the valve chamber 33b, the hole 32, and the oil liquid passage The check valves 29 and 30 are bypassed by 28, the bypass passage 9 is always in communication, the shutter 33 moves upward, and the large-diameter portion 33a has a hole.
When the valve 32 is closed (position B), the check valve 29 is bypassed by the oil liquid passage 27, the hole 31, and the valve chamber 33b, and the bypass passage 9
When the shutter 33 moves downward and the large diameter portion 33a closes the hole 31 (position C), the check valve 30 is opened by the oil passage 28, the hole 32 and the valve chamber 33b. Is bypassed, and the bypass passage 9 is communicated via a check valve 29.

Further, one end of an operating rod 34 is connected to the shutter 33, and the other end of the operating rod 34 is connected to a plunger 36 of a solenoid actuator 35 built in the piston rod 4. And the shutter 33
Is normally in the neutral position A by the spring 38 and the solenoid 37
Can be moved to the positions B and C by energizing.

The operation of the third embodiment configured as described above will now be described.

When the shutter 33 is in the neutral position A, the bypass passage 9 is always in communication, so that the hydraulic fluid in the cylinder 2 is moved by the sliding of the piston 3 in both the extension and contraction strokes as in the first embodiment. Flows through the main oil liquid passage 6 and the bypass passage 9 and a relatively small damping force is generated by the first and second damping force generating mechanisms 7 and 12. Therefore, the damping force characteristic is a soft characteristic on both the extension side and the contraction side as indicated by A in FIG.

When the shutter 33 is located at the upper position B, the bypass passage 9 is communicated via the check valve 30, so that the first
Similarly to the embodiment, during the extension stroke, the oil liquid in the cylinder 2 flows through the main oil liquid passage 6 and the bypass passage 9 and is compared by the first damping force generation mechanism 7 and the second damping force generation mechanism 12. A small damping force is generated. On the other hand, during the contraction process,
Since the flow of the oil liquid in the bypass passage 9 is prevented, the oil liquid in the cylinder 2 flows only through the main oil liquid passage 6 and a relatively large damping force is generated by the first damping force generating mechanism 7. Accordingly, as shown by B in FIG. 3, the damping force characteristic has a soft characteristic on the extension side and a hard characteristic on the contraction side.

When the shutter 33 is at the lower position C, the bypass passage 9 is communicated through the check valve 29.
As in the embodiment, during the contraction stroke, the oil liquid in the cylinder 2 flows through the main oil liquid passage 6 and the bypass passage 9 and is compared by the first damping force generating mechanism 7 and the second damping force generating mechanism 12. A small damping force is generated. On the other hand, during the extension process,
Since the flow of the oil liquid in the bypass passage 9 is blocked, the oil liquid in the cylinder 2 flows only through the main oil liquid passage 6 and a relatively large damping force is generated by the first damping force generating mechanism 7.
Therefore, as shown by C in FIG. 3, the damping force characteristic has a hard characteristic on the extension side and a soft characteristic on the contraction side.

As described above, by moving the shutter 33, the damping force characteristic can be selectively switched from among three types of combinations, as in the first embodiment.

In the third embodiment, as in the first embodiment, the second damping force generating mechanism 12 is omitted, and the holes 29a and 30a are formed as orifices, thereby forming the second damping force. A generating mechanism may be used.

Next, a fourth embodiment of the present invention will be described.

As shown in FIG. 8, a first piston 40 and a second piston 41 are arranged in series and slidably fitted in a cylinder 39 filled with oil. 1,
An oil boundary defining member is formed by the second pistons 40 and 41, and the inside of the cylinder 39 is defined by three cylinder upper chambers 39a, a middle cylinder chamber 39b, and a lower cylinder chamber 39c. One end of a piston rod 42 is penetrated and connected to the first and second pistons 40 and 41, and the other end of the piston rod 42 extends to the outside of the cylinder 39. Further, the cylinder 39 is provided with a reservoir chamber (not shown) for compensating the inflow and outflow of the oil liquid corresponding to the piston rod 42 entering and leaving the cylinder 39.

The first piston 40 has a cylinder upper chamber 39a.
An oil liquid passage 43 is provided for communicating the oil passage 43 with the cylinder inner chamber 39b.
Damping force generating mechanism comprising an orifice and a disc valve for controlling the flow of an oil liquid in the inside to generate a damping force
44 are provided. Further, the second piston 41 is provided with an oil liquid passage 45 for connecting the cylinder middle chamber 39b and the cylinder lower chamber 39c to each other. A second damping force generating mechanism 46 including an orifice and a disc valve for controlling the flow of the oil liquid to generate a damping force is provided. And the oil liquid passage
The main oil passage is constituted by 43 and 45 and the cylinder middle chamber 39b.

The piston rod 42 has openings 47a, 47 extending along the axis from the distal end and communicating with the cylinder upper chamber 39a, the cylinder middle chamber 39b, and the cylinder lower chamber 39c.
A bypass passage 47 having b and 47c is provided. The cylinder upper chamber 39a of the bypass passage 47 and the cylinder middle chamber
38b, a first bypass passage is formed to bypass the first damping force generating mechanism 44. A second damping force generating mechanism is provided between the cylinder middle chamber 39b and the cylinder lower chamber 39c of the bypass passage 47. A second bypass passage that bypasses 46 is formed. A cylindrical passage member 48 is attached to the distal end of the piston rod 42, and the opening of the passage member 48 allows the flow of the oil liquid from the opening 47c of the bypass passage 47 to the cylinder lower chamber 39c side. A check valve 49 is provided to allow and prevent flow in the opposite direction.

A cylindrical passage member 50 is provided so as to surround the opening 47 of the piston rod 42, and the opening of the passage member 50 allows the oil liquid to flow from the opening 47 a of the bypass passage 47 to the cylinder upper chamber 39 a side. A check valve 51 is provided to allow flow and prevent flow in the opposite direction.

A bottomed cylindrical shutter 52 is rotatably fitted in the bypass passage 47 of the piston rod 42 so as to face the opening 47a, and a bottomed cylindrical shutter 53 facing the opening 47c. Are rotatably fitted. A slit 52a is provided in a side wall of the shutter 52, and the opening 47a is opened and closed depending on whether or not the shutter 52 is rotated to align the slit 52a with the opening 47a. Also,
Similarly, a slit 53a is provided on a side wall of the shutter 53, and the shutter 53 is rotated to open the slit 53a in the opening 4.
The opening 47c is opened and closed depending on whether or not it is aligned with 7c.

The shutters 52 and 53 are connected to the piston rod 42
The operation rod 54 extends along the piston rod 42 to the outside of the hydraulic shock absorber. Then, by operating the operation rod 54 from outside the hydraulic shock absorber, the shutter 52 is operated.
And 53 rotate simultaneously.

As shown in FIG. 9, the openings 47a and 47c of the bypass passage 47 are opened in different directions from each other. When the shutters 52 and 53 are at the position a, the slit 52a and the opening are formed. 47a and slit 53a and opening 47
c are communicated with each other, and the slit 52
a and the opening 47a are cut off and the slit 53a and the opening 47
are communicated with each other, the slit 52a and the opening 47a are communicated with each other when the position is at the position c, and the slit 53a and the opening 47c are cut off when the position is at the position d. The slit 53a and the opening 47c are both shut off.

The operation of the fourth embodiment configured as described above will be described.

When the shutters 52 and 53 are at the position a, the openings 47a and 47c of the bypass passage 47 are open.
During the extension stroke of the piston rod 42, the check valve 51 is closed and the oil liquid in the cylinder upper chamber 39a flows through the oil liquid passage 43 of the first piston 40 to the cylinder inner chamber 39b, and the oil liquid in the cylinder inner chamber 39b is opened. The check valve 49 is opened through the portion 47b, the bypass passage 47 and the opening 47c to flow to the cylinder lower chamber 39c. Therefore, a relatively small damping force is generated only by the first damping force generating mechanism 44 of the first piston 40. On the other hand, at the time of the contraction stroke, the check valve 49 is closed and the oil liquid in the cylinder lower chamber 39c flows through the oil liquid passage 45 of the second piston 41 to the cylinder inner chamber 39b, and the oil liquid in the cylinder inner chamber 39b is opened at the opening 47b. The check valve 51 is opened through the bypass passage 47 and the opening 47a, and flows to the cylinder upper chamber 39a. Therefore, a relatively small damping force is generated only by the second damping force generating mechanism 46 of the second piston 41. Therefore, the damping force characteristic is a soft characteristic on both the extension side and the contraction side as shown by a in FIG.

When the shutters 52 and 53 are at the position b, the opening 47a of the bypass passage 47 is closed and the opening 47c is open. 39a is the first piston 40
The oil liquid in the cylinder inner chamber 39b passes through the opening 47b, the bypass passage 47 and the opening 47c, opens the check valve 49, and flows into the cylinder lower chamber 39c. Therefore, a relatively small damping force is generated only by the first damping force generating mechanism 44 of the first piston 40. On the other hand, during the contraction stroke, the check valve 49 is closed and the bypass passage 47 is closed, so that the oil liquid flows through the oil liquid passages 43 and 45 of the first and second pistons 40 and 41 and is arranged in series. 1
A relatively large damping force is generated by the second damping force generating mechanisms 44 and 46. Therefore, the damping force characteristic is represented by b in FIG.
As shown by, the extension side has a soft characteristic and the contraction side has a hard characteristic.

When the shutters 52 and 53 are located at the position c, the opening 47a of the bypass passage 47 is opened and the opening 47c is closed. The oil liquid of 39c is the second piston 41
The oil liquid in the cylinder inner chamber 39b passes through the opening 47b, the bypass passage 47 and the opening 47a, opens the check valve 51, and flows into the cylinder upper chamber 39a. Therefore, a relatively small damping force is generated only by the second damping force generating mechanism 46 of the second piston 41. On the other hand, during the extension stroke, the check valve 51 is closed and the bypass passage 47 is closed, so that the oil liquid flows through the oil liquid passages 43 and 45 of the first and second pistons 40 and 41 as in the case of the position c. First and second damping force generating mechanisms 4 arranged in series by flowing
A relatively large damping force is generated by 4, 46. Therefore,
As shown by c in FIG. 10, the damping force characteristic has a soft characteristic on the contraction side and a hard characteristic on the extension side.

When the shutters 52 and 53 are at the position d, the openings 47a and 47c of the bypass passage 47 are closed, and the bypass passage 47 is always closed. The oil flows through the oil liquid passages 43 and 45 of the second pistons 40 and 41, and a relatively large damping force is generated by the first and second damping force generating mechanisms 44 and 46 arranged in series. Therefore, the damping force characteristic becomes a hard characteristic on both the extension side and the contraction side as shown by d in FIG.

As described above, by moving the shutters 52 and 53 by the operating rod 54, the damping force characteristics are added to the three types of the first, second and third embodiments, and the hard characteristics are added to the extension side and the contraction side. It is possible to selectively switch among four types of combinations.

In the fourth embodiment, the first piston 40 provided with the first damping force generating mechanism 44 and the second piston 41 provided with the second damping force generating mechanism 46 are used. Although the example in which the oil boundary defining member is formed is shown, the invention is not limited to this.
A closed chamber in which the oil passage 43 and the opening 47b communicate with each other is provided below the piston 40, and a second damping force generating mechanism is provided in a place where this chamber communicates with the cylinder lower chamber 39c. Alternatively, the oil boundary defining member may be constituted by one of the first pistons 40.

[0070]

As described above in detail, according to the damping force adjusting type hydraulic shock absorber of the present invention, the damping force characteristics can be selectively switched in different combinations between the extension side and the contraction side. As a result, when used in combination with the suspension control device, the damping force characteristic can be switched to the desired damping force characteristic in the next stroke before the direction of the stroke changes, so that the response delay of the control device is reduced. This provides an excellent effect that the control can be performed sufficiently and the control can be performed appropriately.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a main part of a first embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along line AA and line BB showing a position of a shutter of the apparatus shown in FIG.

FIG. 3 is a diagram showing damping force characteristics of the device of FIG.

FIG. 4 is a longitudinal sectional view of a main part of a second embodiment of the present invention.

FIG. 5 is a diagram showing damping force characteristics of the device of FIG.

FIG. 6 is a diagram showing a change in stroke and a position of a shutter with respect to time when the device of FIG. 1 is controlled by a suspension control device.

FIG. 7 is a longitudinal sectional view of a main part of a third embodiment of the present invention.

FIG. 8 is a longitudinal sectional view of a main part of a fourth embodiment of the present invention.

9 is a cross-sectional view taken along line AA and line BB showing the position of the shutter in the apparatus shown in FIG.

FIG. 10 is a diagram showing damping force characteristics of the device of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Damping force adjustable hydraulic shock absorber 2 Cylinder 2a Upper cylinder chamber 2b Lower cylinder chamber 3 Piston 4 Piston rod 6 Main oil liquid passage 7 First damping force generation mechanism 9 Bypass passage 12 Second damping force generation mechanism 13 Guide member (First and second damping force control valves) 14 Check valve (first check valve) 15 Check valve (second check valve) 20 Shutter (first and second damping force control valves)

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-139937 (JP, A) JP-A-2-106420 (JP, A) JP-A-1-229128 (JP, A) 181136 (JP, U) U.S. Pat. No. 4,671,392 (US, A) U.K. Patent Application No. 2340441 (GB, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16F 9/46 B60G 17/08

Claims (2)

(57) [Claims] 1. A cylinder filled with an oil liquid, a piston slidably fitted in the cylinder and defining the inside of the cylinder as two chambers, one end connected to the piston, and the other end connected to the piston. A piston rod extending to the outside of the cylinder, a main oil liquid passage communicating with the two chambers and having a damping force generating mechanism, a bypass passage bypassing the damping force generating mechanism and communicating the two chambers, A first check valve and a second check valve that are provided in series with the bypass passage and allow flow in mutually opposite directions, a first oil liquid passage that bypasses the first check valve, A second oil passage that bypasses a second check valve; a first damping force adjusting valve that varies a passage area of the first oil passage; and a passage area of the second oil passage. the a second damping force control valve for a variable, the first and second damping force control valve Are the first and second
Open both oil passage areas, one open and the other
Closed or selectively adjusted so that one is closed and the other is open
A damping force-adjustable hydraulic shock absorber characterized by being made possible. 2. A cylinder filled with an oil liquid, an oil boundary defining member slidably fitted in the cylinder and defining an interior of the cylinder into two chambers, and one end side of the oil boundary defining member. A main oil passage communicating with the two chambers, and a first damping force provided in the main oil passage to generate a damping force. Generating mechanism,
A second damping force generating mechanism that is provided in series with the first damping force generating mechanism in the main oil liquid passage and generates a damping force; and a first bypass passage that bypasses the first damping force generating mechanism. And a second bypassing the second damping force generating mechanism.
And a first and a second check valve provided in each of the first and second bypass passages and allowing flow in different directions, and a passage area of the first bypass passage is variable. And a second damping force adjusting valve that varies a passage area of the second bypass passage , wherein the first and second damping force adjusting valves are configured to be connected to the first damping force adjusting valve. And the second
Open both oil passage areas, one open and the other
Closed or selectively adjusted so that one is closed and the other is open
A damping force-adjustable hydraulic shock absorber characterized by being made possible.