JPH05178058A - Suspension controller - Google Patents

Abstract

PURPOSE:To provide a suspension controller in which a hydraulic buffer changes over to a desired damping force property in the following stroke before changing the direction of the stroke. CONSTITUTION:Between the car body 2 side and wheel 3 side of a vehicle, a suspension spring 4 and a hydraulic buffer 5 having a damping force property selectively changed over in four combinations of soft/soft, soft/hard, hard/soft and hard/hard on the expansion side/contraction side, are interposed. The change-over to the similar damping force properties (change-over from soft to soft and from hard to hard) among the four combinations of the damping force properties is performed in one stroke of the hydraulic buffer 5 by a controller 8 on the basis of the detection of an acceleration sensor 6 and ground clearance sensor 7 to change over the hydraulic buffer 5 for obtaining a desired damping force property in the following stroke. Since the damping force property is changed over to the desired one in the following stroke before the direction of stroke of the hydraulic buffer 5 is changed, i.e., before the stroke speed becomes zero, shocks are not caused by the sudden change of the damping force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension control device for automatically switching the damping force characteristics of a damping force adjusting hydraulic shock absorber mounted on a suspension device according to the running condition of a vehicle. is there.

[0002]

2. Description of the Related Art A hydraulic shock absorber mounted on a suspension device of an automobile or the like has a damping force characteristic of a relatively small damping force in order to improve ride comfort and steering stability in accordance with road surface conditions and running conditions. There is a damping force adjustable hydraulic shock absorber capable of appropriately switching between a soft characteristic for generating a force and a hard characteristic for generating a relatively large damping force.

Further, an actuator for switching the damping force characteristic of a damping force adjusting type hydraulic shock absorber mounted on a suspension device of a vehicle and a control device for outputting an operation signal to this actuator according to a road surface condition, a running condition and the like are provided. Provided,
There is a suspension control device that improves the ride comfort and steering stability of a vehicle by automatically switching the damping force characteristics of a hydraulic shock absorber during traveling.

In this type of suspension control device, for example, the absolute velocity on the spring of the suspension device and the relative velocity between the sprung portion and the unsprung portion are detected, and the damping force is determined according to the sign (positive or negative) of these products. A control method is used in which the characteristics are switched, or the damping force characteristics are switched according to the sign of the product by detecting the relative displacement and relative velocity between the sprung and unsprung parts. ..

[0005]

By the way, generally, when the damping force characteristic is switched during the stroke of the operating rod (piston rod) of the hydraulic shock absorber, the sprung acceleration of the vehicle suddenly changes due to the rapid change of the damping force. As a result, there is a problem that the riding comfort is deteriorated and the impact noise is generated. This effect is particularly remarkable when the damping force characteristic is switched from the soft side to the hard side.

In order to solve this problem, when the damping force generated by the hydraulic shock absorber is zero, that is, when the stroke speed of the operating rod is zero, the damping force characteristic is switched so that the damping force suddenly changes. You should prevent the change.

Therefore, in the case of the above-mentioned conventional suspension control device, it is determined by the control device that the relative speed between the sprung and unsprung parts has become zero, and at this time, the damping force characteristic is switched. However, it usually takes about 15 to 20 msec until the control device detects the relative speed between the sprung and unsprung parts and outputs a switching signal, and the actuator operates to switch the damping force characteristics of the hydraulic shock absorber. Therefore,
Since there is a large phase delay with respect to high-frequency vibration, there is a problem in that it cannot correspond to the actual running state.

The present invention has been made in view of the above points, and when the stroke speed of the operating rod of the hydraulic shock absorber is zero, the switching to the desired damping force characteristic can be completed in the subsequent subsequent stroke. It is an object of the present invention to provide a suspension control device as described above.

[0009]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a damping force adjusting type hydraulic shock absorber interposed between a wheel side and a vehicle body side of a suspension device of a vehicle. In the suspension control device in which the characteristics are appropriately switched by the control device according to the running situation, the damping force adjusting type hydraulic shock absorber has damping force characteristics such that the extension side is soft and the contraction side is soft, and the extension side is soft and the contraction side is The control device includes damping force adjusting means that can be selectively switched from at least three combinations of hard and extending sides being hard and contracting sides being soft, and the control device is configured to extend or contract one of the damping force adjustable hydraulic shock absorbers. During the stroke, the damping force characteristic is not switched or is switched during the one stroke so that the damping force characteristic becomes hard or soft in the next stroke of contraction or extension. And outputs a control signal to perform switching to the damping force characteristic of like to the damping force adjusting means.

Further, according to the present invention, the damping force characteristic of the damping force adjusting type hydraulic shock absorber interposed between the wheel side and the vehicle body side of the vehicle suspension device can be appropriately switched by the control device according to the running situation. In the suspension control device described above, the damping force adjusting type hydraulic shock absorber has at least three damping force characteristics: soft on the extension side and soft on the contraction side, soft on the extension side and hard on the contraction side, and hard on the extension side and soft on the contraction side. The control device is provided with a damping force adjusting means that can be selectively switched from a combination, and the control device is configured such that, during one stroke of expansion or contraction of the damping force adjustable hydraulic shock absorber, the damping force is adjusted in the next stroke of contraction or extension. Non-switching of damping force characteristics during the one stroke, switching to similar damping force characteristics, or the hardware side so that the characteristics are as desired between hard and soft. Suspension control unit and outputs a control signal to perform switching to Luo soft side to the damping force adjusting means.

[0011]

With this configuration, the damping force characteristic of the damping force adjusting type hydraulic shock absorber can be changed to a similar damping force characteristic even when the damping force is switched during one stroke of expansion or contraction. Since the switching from the side to the soft side is performed, the impact due to the rapid change of the damping force at the time of switching is small, and then the desired damping force characteristic in the next stroke is changed before the stroke direction changes and the next stroke starts. Therefore, the shock due to the switching to the desired damping force characteristic in the next stroke does not occur.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

The overall configuration of the suspension control device 1 of the present invention will be described with reference to FIG. Hereinafter, the case of performing control for one wheel of the vehicle will be described.

As shown in FIG. 1, the suspension control device 1 includes a suspension spring 4 and a damping force adjusting hydraulic shock absorber 5 (between a vehicle body 2 side (spring side) and a wheel 3 side (unsprung side) of a vehicle. Hereinafter, the hydraulic shock absorber 5) is interposed and the vehicle body 1 is supported. An acceleration sensor 6 for detecting a vibration state of the vehicle body 2 side is provided on the vehicle body 2 side, and a stroke of an operating rod (piston rod) of the hydraulic shock absorber 5 is provided between the vehicle body 2 side and the wheel 3 side. A vehicle height sensor 7 for detecting The hydraulic shock absorber 5, the acceleration sensor 6, and the vehicle height sensor 7 are connected to a controller 8 (control device), and the controller 8 hydraulically buffers a control signal based on the detection signals from the acceleration sensor 6 and the vehicle height sensor 7. The output is output to the device 5 to switch the damping force characteristic.

As shown in FIG. 2, the hydraulic shock absorber 5 includes a cylinder 9 in which oil liquid is sealed, and a cylinder upper chamber 9a and a lower cylinder chamber 9b which are slidably fitted in the cylinder 9 and are arranged in the cylinder 9.
And a piston rod (actuating rod) 11 connected to the piston 10 and extending to the outside of the cylinder 9. The piston 10 has
A hydraulic circuit that connects the cylinder upper chamber 9a and the cylinder lower chamber 9b.
10a is provided.

This hydraulic circuit 10a includes a first damping force generating mechanism 12 and a second damping force generating mechanism 12 having a stretching side and contracting side damping force generating mechanism.
The first bypass passage 14 that bypasses the first damping force generating mechanism 12 is arranged in series with the damping force generating mechanism 13 of FIG.
A second bypass passage 15 that bypasses the second damping force generating mechanism 13 is also provided. The first and second bypass passages 14 and 15 are provided with check valves 16 and 17 and a damping force adjusting valve 18, which allow oil liquids to flow in opposite directions.

The damping force adjusting valve 18 is a three-port four-position switching valve, and at the position A, the first bypass passage 14 is shut off and the second damping valve 18 is closed.
The bypass passage is communicated with the first and second bypass passages 14 and 15 at position B, and the first bypass passage at position C.
The second bypass passage is cut off by communicating 14 with each other, and at the position D, both the first and second bypass passages 14 and 15 are cut off. In the figure, 19 is an actuator for switching the damping force adjusting valve 18, which constitutes a damping force adjusting means together with the above-mentioned hydraulic circuit 10a.

With this configuration, when the damping force adjusting valve 18 is in the position A, the hydraulic shock absorber 5 shuts off the first bypass passage 14 and connects the second bypass passage. The check valve 17 of the second bypass passage 15 is opened, and the oil liquid in the cylinder 9 flows through the first damping force generating mechanism 12 and the second bypass passage 15. Therefore, the first damping force generating mechanism 12
Only a relatively small damping force is generated by this. During the compression stroke, the check valve 17 of the second bypass passage 15 is closed, and the oil liquid in the cylinder 9 flows through the first damping force generating mechanism 12 and the second damping force generating mechanism 13. A relatively large damping force is generated by the second damping force generating mechanisms 12 and 13. Therefore, the damping force characteristic is a soft characteristic on the extension side and a hard characteristic on the contraction side.

When the damping force adjusting valve 18 is in the position B, both the first and second bypass passages 14 and 15 are communicated with each other, so that the check valve 16 of the first bypass passage 14 is closed during the extension stroke. ,
Since the check valve 17 of the second bypass passage 15 is opened and the oil liquid in the cylinder 9 flows through the first damping force generating mechanism 12 and the second bypass passage 15, only the first damping force generating mechanism 12 is provided. Causes a relatively small damping force. During the compression stroke, the check valve 16 of the first bypass passage 14 is opened, the check valve 17 of the second bypass passage 15 is closed, and the oil liquid in the cylinder 9 is absorbed by the second damping force generating mechanism 13 and the second damping force generating mechanism 13. Since it flows through the first bypass passage 14, a relatively small damping force is generated only by the second damping force generating mechanism 13. Therefore, the damping force characteristic is a soft characteristic on both the extension side and the contraction side.

When the damping force control valve 18 is in the position C, the first
Since the bypass passage 14 is connected and the second bypass passage is shut off, the check valve 14 of the first bypass passage 14 is closed and the oil liquid in the cylinder 9 is attenuated to the first and second damping strokes during the extension stroke. Since it flows through the force generating mechanisms 12 and 13, a relatively large damping force is generated. Check valve of the first bypass passage 14 during the compression stroke
16 is opened, and the oil in the cylinder 9 is the second damping force generation mechanism.
Since it circulates through 13 and the first bypass passage 14, a relatively small damping force is generated only by the second damping force generating mechanism 13. Therefore, the damping force characteristic is a hard characteristic on the extension side and a soft characteristic on the contraction side.

When the damping force adjusting valve 18 is at the position D, both the first and second bypass passages 14 and 15 are shut off, so that the oil liquid in the cylinder 9 has the first damping force during both the expansion and contraction strokes. Since it flows through the generating mechanism 12 and the second damping force generating mechanism 13, a relatively large damping force is generated during both the expansion and contraction strokes. Therefore, the damping force characteristics are hard characteristics on both the extension side and the contraction side.

By switching the damping force adjusting valve 18 in this manner, the damping force characteristics are shown as follows: Position A: extension side / soft (A ₁ ) Contraction side / hard (A ₂ ) Position B: extension side / soft (B ₁ ) Shrink side / Soft (B ₂ ) Position C: Stretch side / Hard (C ₁ ) Shrink side / Soft (C ₂ ) Position D: Stretch side / Hard (D ₁ ) Shrink side / Hard (D ₂ ) It is possible to selectively switch from the combination of.

Further, the hydraulic circuit of the hydraulic shock absorber 5 can also achieve the same operation by being configured as shown in FIG. Next, in the hydraulic circuit 20 shown in FIG. 3, the same members as those in FIG. 2 are designated by the same reference numerals, and only different portions will be described in detail.

The hydraulic circuit 20, which serves as a damping force adjusting means together with the actuator 19, has a main oil liquid passage having a first damping force generating mechanism 21 (large damping force) which connects the cylinder upper chamber 9a and the cylinder lower chamber 9b. 22 and a bypass passage 24 having a second damping force generating mechanism 23. The bypass passage 24 includes check valves 25 arranged in series that allow flow in opposite directions.
26 are provided. Further, an oil liquid passage 27 that bypasses the check valve 25 and an oil liquid passage 28 that bypasses the check valve 26 are provided, and a damping force adjusting valve 29 is provided in the oil liquid passages 27 and 28.

The damping force adjusting valve 29 is a three-port four-position switching valve, which communicates with the oil liquid passage 27 at position A and shuts off the oil liquid passage 28, and at position B communicates with both oil liquid passages 27 and 28. , Position C
Then, the oil liquid passage 27 is shut off and the oil liquid passage 28 is communicated with the position D
The oil liquid passages 27 and 28 are both shut off.

With this configuration, the damping force adjusting valve 29 is set to the position A.
In the case of, since the check valve 25 is bypassed by the oil liquid passage 27, the check valve 26 of the bypass passage 24 opens and the oil liquid in the cylinder 9 flows through the bypass passage 24 during the extension stroke. The second damping force generating mechanism 23 generates a relatively small damping force. Check valve 26 in bypass passage 24 during the compression stroke
Is closed, the bypass passage 24 is blocked, and the oil liquid in the cylinder 9 flows only through the main oil liquid passage 22, so that a relatively large damping force is generated by the first damping force generating mechanism 21. Therefore,
Regarding the damping force characteristics, the extension side has a soft characteristic and the contraction side has a hard characteristic.

When the damping force adjusting valve 29 is in the position B, both the check valves 25 and 26 are bypassed by the oil liquid passages 27 and 28, so that the oil liquid in the cylinder 9 is bypassed during the expansion and contraction strokes. Since it circulates through 24, a relatively small damping force is generated by the second damping force generating mechanism 23 during both the expansion and contraction strokes. Therefore, the damping force characteristic is a soft characteristic on both the extension side and the contraction side.

When the damping force adjusting valve 29 is at the position C, the check valve 26 is bypassed by the oil passage 28, so that the check valve 25 of the bypass passage 24 is closed during the extension stroke.
Since 24 is shut off and the oil liquid in the cylinder 9 flows only through the main oil liquid passage 22, a relatively large damping force is generated by the first damping force generating mechanism 21. Bypass passage 24 during the contraction process
The check valve 25 is opened to communicate the bypass passage 24, and the oil liquid in the cylinder 9 flows through the bypass passage 24. Therefore, the second damping force generating mechanism 23 generates a relatively small damping force. Therefore, the damping force characteristic is a hard characteristic on the extension side and a soft characteristic on the contraction side.

When the damping force adjusting valve 29 is at the position D, both the oil liquid passages 27 and 28 are shut off, so that the check valves 25 and 26 extend and the bypass passage 24 is shut off during the compression stroke. During the expansion and contraction strokes, the oil liquid in the cylinder 9 flows only through the main oil liquid passage 22 and a relatively large damping force is generated by the first damping force generating mechanism 21. Therefore, the damping force characteristics are
Hard characteristics on both sides of expansion and contraction.

In this way, by switching the damping force adjusting valve 29, it is possible to selectively switch among four types of combinations, as in the case shown in FIG.

The hydraulic shock absorber 5 shown in FIG. 4 is different from the hydraulic shock absorber shown in FIG. 3 in that the damping force adjusting valve 29 is replaced with a 3-port 3-position switching valve 30 in which the position D is omitted. In this case, the damping force characteristics can be selectively switched from among the four types among the three types of combinations except the combination corresponding to the position D.

Next, an example of a specific structure of the hydraulic shock absorber shown in FIG. 2 will be described with reference to FIGS.

As shown in FIG. 5, a first piston 32 and a second piston 33 are arranged in series and slidably fitted in a cylinder 31 in which an oil liquid is sealed.
The inside is divided into three chambers, a cylinder upper chamber 31a, a cylinder middle chamber 31b, and a cylinder lower chamber 31c. One end side of a piston rod 34 penetrates and is connected to the first and second pistons 32 and 33, and the other end of the piston rod 34 is a cylinder.
It has been extended to the outside of 31. In addition, in the cylinder 31,
A reservoir chamber (not shown) is provided for compensating for the oil liquid entering and leaving the piston rod 34 into and out of the cylinder 31.

The piston 32 is provided with an oil liquid passage 35 for communicating the cylinder upper chamber 31a and the cylinder middle chamber 31b, and the flow of the oil liquid in the oil liquid passage 35 is provided on both end faces of the piston 32. A damping force generation mechanism 36 is provided as a first damping force generation mechanism including an orifice and a disc valve that generate a damping force by control. Also, the piston 33 has
An oil passage 37 is provided which connects the cylinder inner chamber 31b and the cylinder lower chamber 31c to each other.
A damping force generating mechanism 38 is provided as a second damping force generating mechanism including an orifice and a disc valve for controlling the flow of the oil liquid in the oil liquid passage 37 to generate a damping force. The oil liquid passages 35 and 37 and the cylinder inner chamber 31b constitute a main oil liquid passage.

The piston rod 34 has openings 39a, 39 extending from the tip end along the axis and communicating with the cylinder upper chamber 31a, the cylinder middle chamber 31b and the cylinder lower chamber 31c, respectively.
A bypass passage 39 having b and 39c is provided. Then, the cylinder upper chamber 31a and the cylinder middle chamber of the bypass passage 39
A first bypass passage 39d that bypasses the damping force generation mechanism 36 is formed between the bypass passage 39 and the cylinder inner chamber 31b and the cylinder lower chamber 31c of the bypass passage 39.
Forming a second bypass passage 39e for bypassing. A cylindrical passage member is provided at the tip of the piston rod 34.
A check valve 40 is attached to the opening of the passage member 40, which allows the oil liquid to flow from the opening 39c of the bypass passage 39 to the cylinder lower chamber 31c side and blocks the flow in the opposite direction. 41 are provided.

A cylindrical passage member 42 is provided so as to surround the opening 39 of the piston rod 34, and the opening of the passage member 42 is filled with oil liquid from the opening 39a of the bypass passage 39 to the cylinder upper chamber 31a side. A check valve 43 is provided which allows the flow and blocks the flow in the opposite direction.

A bottomed cylindrical shutter 44 is rotatably fitted in the bypass passage 39 of the piston rod 34 so as to face the opening 39a, and a bottomed cylindrical shutter 45 faces the opening 39c. Are rotatably fitted together. A slit 44a is provided on the side wall of the shutter 44, and the opening 39a is opened and closed depending on whether or not the shutter 44 is rotated to align the slit 44a with the opening 39a. Also,
Similarly, a slit 45a is provided on the side wall of the shutter 45, and the shutter 45 is rotated to open the slit 45a in the opening 3.
The opening 39c is opened and closed depending on whether or not it is aligned with 9c.

The shutters 44 and 45 are for the piston rod 34.
Is connected together with an operating rod 46 extending along the axis of the operating rod 46, and the operating rod 46 extends along the piston rod 34 to the outside of the hydraulic shock absorber. Then, the shutter 44 is operated by operating the operation rod 46 from the outside of the hydraulic shock absorber.
And 45 are designed to rotate simultaneously.

As shown in FIG. 6, the openings 39a and 39c of the bypass passage 39 are opened in directions different from each other, and when the shutters 44 and 45 are at the position A, the slits 44a and the openings are formed. 39a is cut off and the slit 45a and the opening 39c are communicated with each other.
44a and the opening 39a and the slit 45a and the opening 39c are communicated with each other, and when in the position C, the slit 44a and the opening 39a are communicated with each other to cut off the slit 45a and the opening 39c, and the position D In the case of, the slit 44a and the opening 39a and the slit 45a and the opening 39c are both blocked.

In the hydraulic shock absorber shown in FIG. 5, the first and second pistons 32 and 33 are used for the piston 10 of FIG. 2, the damping force generating mechanism 36 is used for the first damping force generating mechanism 12, and the damping force is generated. The mechanism 38 is the second damping force generating mechanism 13, and the check valve 43 is the check valve 16.
The check valve 41 to the check valve 17, the shutter 44 and the shutter.
45 corresponds to the damping force adjusting valve 18, and shutters 44, 45
The position of corresponds to the switching position of the damping force adjusting valve 18.

The operation of this configuration will be described. When the shutters 44 and 45 are at the position A, the opening 39a of the bypass passage 39 is closed and the opening 39c is opened, so that the check valve 43 is closed during the extension stroke of the piston rod 34 and the cylinder upper chamber is closed.
The oil liquid of 31a flows into the cylinder inner chamber 31b through the oil liquid passage 35 of the piston 32, and the oil liquid of the cylinder inner chamber 31b is opened 39b.
, Through the second bypass passage 39e and the opening 39c to open the check valve 41 and flow into the cylinder lower chamber 31c. Therefore, a relatively small damping force is generated only by the damping force generation mechanism 36 of the piston 32. On the other hand, during the compression stroke, the check valve 41 is closed and the bypass passage 39 is closed, so that the oil liquid is transferred to the piston 32.
A relatively large damping force is generated by the damping force generating mechanisms 36 and 38 that are arranged in series by flowing through the oil liquid passages 35 and 37 of 33 and 33. Therefore, the damping force characteristic becomes a soft characteristic on the extension side and a hard characteristic on the contraction side as indicated by A in FIG.

Since the openings 39a and 39c of the bypass passage 39 are open when the shutters 44 and 45 are at the position B,
During the extension stroke of the piston rod 34, as in the case of the position A, the oil liquid in the cylinder upper chamber 31a flows into the oil liquid passage 35 of the piston 32.
And flows into the cylinder inner chamber 31b, and the oil liquid in the cylinder inner chamber 31b passes through the opening 39b, the second bypass passage 39e and the opening 39c, opens the check valve 41, and flows into the cylinder lower chamber 31c. Therefore, a relatively small damping force is generated only by the damping force generation mechanism 36 of the piston 32. On the other hand, during the compression stroke, the check valve 41 is closed and the oil liquid in the cylinder lower chamber 31c flows into the cylinder inner chamber 31b through the oil liquid passage 37 of the piston 33, and the oil liquid in the cylinder inner chamber 31b is opened at the opening 39b, the first Bypass passage 39d
And the opening 39a to open the check valve 43 to open the cylinder upper chamber.
It flows to 31a. Therefore, the damping force generation mechanism 38 of the piston 33 is
Only a relatively small damping force is generated by this. Therefore, the damping force characteristic is a soft characteristic on both the extension side and the contraction side as indicated by B in FIG.

When the shutters 44 and 45 are in the position C, the opening 39a of the bypass passage 39 is opened and the opening 39c is closed. Therefore, during the compression stroke of the piston rod 34, as in the case of the position B, the lower chamber of the cylinder is closed. The oil liquid in 31c flows into the cylinder inner chamber 31b through the oil liquid passage 37 in the piston 33,
The oil liquid in 31b passes through the opening 39b, the first bypass passage 39d and the opening 39a to open the check valve 43 and open the cylinder upper chamber 31a.
Flows to. Therefore, a relatively small damping force is generated only by the damping force generation mechanism 38 of the piston 33. On the other hand, during the extension stroke, the check valve 43 is closed and the first bypass passage 39d is closed, so that the oil liquid passes through the oil liquid passages 35 of the pistons 32 and 33.
A relatively large damping force is generated by the damping force generating mechanisms 36 and 38 that flow in the 37 and are arranged in series. Therefore, the damping force characteristic is a hard characteristic on the extension side and a soft characteristic on the contraction side, as indicated by C in FIG.

When the shutters 44 and 45 are at the position D, the openings 39a and 39c of the bypass passage 39 are closed, and the bypass passage 39 is always closed. Flowing through the oil passages 35 and 37 of 33,
A relatively large damping force is generated by the damping force generating mechanisms 36 and 38 arranged in series. Therefore, the damping force characteristics are hard characteristics on both the extension side and the contraction side, as indicated by D in FIG.

In this way, by moving the shutters 44, 45 with the operation rod 46, the damping force characteristics are displayed at position A: extension side / soft (A ₁ ) compression side / hard (A ₂ ) position B: extension side / Soft (B ₁ ) Shrink side / Soft (B ₂ ) Position C: Stretch side / Hard (C ₁ ) Shrink side / Soft (C ₂ ) Position D: Stretch side / Hard (D ₁ ) Shrink side / Hard (D ₂ ) It is possible to selectively switch from the four combinations.

Next, an example of a specific structure of the hydraulic shock absorber shown in FIG. 4 will be described with reference to FIGS. 8 to 10.

As shown in FIG. 8, a piston 48 is slidably fitted in a cylinder 47 filled with an oil liquid, and the inside of the cylinder 47 is moved to the cylinder upper chamber 47a by this piston 48.
And a cylinder lower chamber 47b. The piston 48 has a piston rod 49 extending at the base end side that extends to the outside of the cylinder 47.
The cylindrical passage member 50 is screwed to the base end portion of the. The cylinder 47 is provided with a reservoir chamber (not shown) for compensating for the inflow and outflow of the oil liquid corresponding to the piston rod 49 entering and leaving the cylinder 47.

The piston 48 is provided with a main oil liquid passage 51 for communicating the cylinder upper chamber 47a and the cylinder lower chamber 47b, and the flow of the oil liquid in the main oil liquid passage 51 is provided on both end faces of the piston 48. A damping force generation mechanism 52 (large damping force) including an orifice and a disc valve that controls the above to generate a damping force is provided.

The piston rod 49 is provided with an oil liquid passage 53 having one end communicating with the cylinder upper chamber 47a and the other end communicating with the passage member 50 on the cylinder lower chamber 47b side. The passage member 50 constitutes a bypass passage 54 that connects the cylinder upper chamber 47a and the cylinder lower chamber 47b.

A valve main body 56 having an oil liquid passage 55 communicating with the bypass passage 54 is fitted in the opening of the passage member 50 on the cylinder lower chamber 47b side. A damping force generating mechanism 57 (small damping force) including an orifice and a disc valve that controls the flow of the oil liquid in the passage 55 to generate a damping force is provided.

A cylindrical guide member 58 is provided in the passage member 50.
Are fitted. At the end of the guide member 58 on the cylinder upper chamber 47a side, a check valve 59 that allows the flow of oil liquid from the inside of the guide member 58 to the cylinder upper chamber 47a side and blocks the flow of oil liquid in the opposite direction 59 Is provided to allow the oil liquid to flow from the inside of the guide member 58 to the cylinder lower chamber 47b side at the end of the guide member 58 on the cylinder lower chamber 47b side, and prevent the oil liquid from flowing in the opposite direction. A check valve 60 is provided.

In the bypass passage 54, between the passage member 50 and the guide member 58, an oil liquid passage 61 communicating with the cylinder upper chamber 47a side and an oil liquid passage communicating with the cylinder lower chamber 47b side.
62 are formed, and a hole 63 communicating with the oil liquid passage 61 and a hole 64 communicating with the oil liquid passage 62 are formed on the side wall of the guide member 58.
Is provided, the oil liquid passage 61 and the hole 63 constitute a first oil liquid passage that bypasses the check valve 59, and the oil liquid passage 62 and the hole 64 are provided.
And constitute a second oil liquid passage that bypasses the check valve 60.

Inside the guide member 58, a cylindrical shutter 65 having a bottom is rotatably fitted as first and second damping force adjusting valves. An oil liquid passage 66 that connects the inside of the shutter 65 and the check valve 59 side is provided at the bottom of the shutter 65. A pair of slits 67 are formed on the side wall of the shutter 65. The first slit is formed depending on whether the shutter 65 is rotated to align the slits 67 with the holes 63 of the guide member 58.
And the second oil passage can be opened and closed.

As shown in FIG. 9, the holes 63 of the guide member 58 and
64 is an opening from the center of the guide member 58 in directions different from each other, and when it is at position A, it is a slit.
Only 67 and the hole 64 are aligned, and when the shutter 65 is at the position B, the slit 67 and the holes 63 and 64 are aligned, and when the shutter 65 is at the position C, only the slit 67 and the hole 63 are aligned. It has become. An operating rod 68 is connected to the bottom of the shutter 65, and the operating rod 68 penetrates the check valve 59 and is connected to the piston rod.
The shutter 65 is extended along the line 49 to the outside, and the shutter 65 can be rotated from the outside of the damping force adjusting hydraulic shock absorber 1.

In the hydraulic shock absorber shown in FIG. 8, the main oil liquid passage 51 is provided in the main oil liquid passage 22 shown in FIG.
To the first damping force generating mechanism 21 in FIG. 4, the bypass passage 54 to the bypass passage 24 in FIG. 4, the damping force generating mechanism 57 to the second damping force generating mechanism 23 in FIG. 60 is the check valve in FIG.
25 and 26, the shutter 65 corresponds to the damping force adjusting valve 30 of FIG. 4, and the position of the shutter 65 corresponds to the switching position of the damping force adjusting valve 30.

The operation of this configuration will be described. The damping force characteristic can be switched by operating the operation rod 68 from the outside to rotate the shutter 65.

As shown in FIG. 9, when the shutter 65 is at the position A, the check valve 59 is bypassed by the oil passage 61 and the hole 63 by aligning the hole 63 with the slit 67. On the other hand, the hole 64 is closed by the shutter 65. Therefore, the bypass passage 54 is communicated via the check valve 60, and the cylinder upper chamber 47a side is connected to the cylinder lower chamber 47a.
The oil liquid is allowed to flow to the b side, and the oil liquid is prevented from flowing in the opposite direction. Therefore, during the extension stroke of the piston rod 49, the oil liquid in the cylinder 47 flows through the main oil liquid passage 51 and the bypass passage 54 due to the sliding of the piston 48, and the damping force generating mechanisms 52 and 57 generate relatively small damping force. Occurs. On the other hand, during the contraction stroke, the flow of the oil liquid in the bypass passage 54 is blocked, so that the sliding of the piston 48 causes the oil liquid in the cylinder 47 to flow only in the main oil liquid passage 51 so that the damping force generating mechanism 52 causes A relatively large damping force is generated. Therefore, as shown by A in FIG. 10, the damping force characteristic has a soft characteristic on the extension side and a hard characteristic on the contraction side.

When the shutter 65 is at the position B, the hole 63 and the slit 67 are aligned so that the oil liquid passage 61 and the hole 63 are aligned.
The check valve 59 is bypassed by, and the check valve 60 is bypassed by the oil liquid passage 62 and the hole 64 by aligning the hole 64 with the slit 67. Therefore, since the bypass passage 54 is always communicated, the oil liquid in the cylinder 47 is slid by the sliding of the piston 48 accompanying the expansion and contraction of the piston rod 49 in both the extension and contraction strokes.
A relatively small damping force is generated through the damping force generating mechanisms 52 and 57 flowing through 54. Therefore, the damping force characteristics are shown in Fig. 10.
As indicated by B in the figure, both the expansion side and the contraction side have soft characteristics.

When the shutter 65 is at the position C, the hole 63 is
It is closed by the shutter 65. On the other hand, hole 64 and slit 67
The check valve 60 is bypassed by the oil passage 62 and the hole 64 due to the matching of and. Therefore, the bypass passage 54
Is communicated via the check valve 59, allowing the oil liquid to flow from the cylinder lower chamber 47b side to the cylinder upper chamber 47a side and preventing the oil liquid from flowing in the opposite direction. Become. Therefore, during the compression stroke of the piston rod 49, the oil liquid in the cylinder 47 flows through the main oil liquid passage 51 and the bypass passage 54 due to the sliding of the piston 48, and the damping force generation mechanism 52 and
57 produces a relatively small damping force. On the other hand, during the extension stroke, the circulation of the oil liquid in the bypass passage 54 is blocked, so that the oil liquid in the cylinder 47 is circulated only in the main oil liquid passage 51 by the sliding of the piston 48, and the damping force generating mechanism 52 causes A relatively large damping force is generated. Therefore, the damping force characteristics are
As indicated by C in 10, the stretch side has hard characteristics and the shrink side has soft characteristics.

In this way, by rotating the shutter 65 and changing its position, the damping force characteristics are changed to position A: extension side / soft (A ₁ ) compression side / hard (A ₂ ) position B: extension side / Soft (B ₁ ) shrink side / soft (B ₂ ) position C: extension side / hard (C ₁ ) shrink side / soft (C ₂ ) It is possible to selectively switch from among the three combinations.

Next, the controller 8 will be described.
The controller 8 includes an acceleration sensor 6 and a vehicle height sensor 7.
The damping force characteristic of the hydraulic shock absorber 5 is selected from the four combinations on the basis of the detection signal from and the control signal for operating the actuator for switching the damping force characteristic of the hydraulic shock absorber 5 is output.

The first control method by the controller 8 will be described. The damping force characteristics are switched by four groups of damping force characteristics during one stroke (extension or contraction stroke) in the expansion and contraction stroke of the piston rod 11 of the hydraulic shock absorber 5 due to the sprung and unsprung vibrations that occur during traveling. Among the adjustments, switching to similar damping force characteristics is performed. That is, only the soft characteristic is switched to the soft characteristic and the hard characteristic is switched to the hard characteristic.

Therefore, the switching of the damping force characteristic of the hydraulic shock absorber 5 is performed according to the pattern shown in FIG. FIG. 11 shows the relationship between the damping force characteristic of one arbitrary stroke (current stroke) and the damping force characteristic of the next stroke (next stroke). The damping force characteristics on the hard side are shown in the upper row, the damping force characteristics on the soft side are shown in the lower row, and the four damping force characteristics that the hydraulic shock absorber 5 can take on the hard side and the soft side are shown in circles. The upper part of the circle shows the damping force characteristic on the extension side, and the lower part shows the damping force characteristic on the contraction side. In the figure,
The thin arrow indicates switching of the position of the damping force adjusting valve of the hydraulic shock absorber by the control signal of the controller 8, and the position of the damping force adjusting valve that can be changed during the extension stroke is shown above the arrow.
The position of the damping force control valve which can be switched during the compression stroke is shown below the arrow. In the figure, the thick arrows indicate the change in the stroke from extension to contraction or from contraction to extension.When changing from extension to contraction stroke, the symbol above the arrow corresponds to the position of the damping force control valve. The damping force characteristic switches along the arrow, and when the compression stroke changes to the extension stroke, the damping force characteristic switches along the arrow where the symbol shown below the arrow matches the position of the damping force control valve. It will be.

Therefore, the damping force characteristics can be switched as follows. When switching from the current stroke (extension / hard side) to the next stroke (shrink / hard side), set the damping force adjusting valve to position D at the current stroke.
When switching to the current stroke (extension / hard side) to the next stroke (shrink / soft side), set the damping force adjusting valve to position C at the current stroke.
When switching to the current stroke (extension / soft side) to the next stroke (shrink / soft side), set the damping force adjusting valve to position B at the current stroke.
When switching to the current stroke (extension / soft side) to the next stroke (shrink / hard side), set the damping force adjusting valve to position A at the current stroke.
When switching to the current stroke (shrink / hard side) to the next stroke (extension / hard side), set the damping force adjusting valve to position D at the current stroke.
When switching to the current stroke (shrink / hard side) to the next stroke (extension / soft side), set the damping force adjusting valve to position A at the current stroke.
When switching to the current stroke (shrink / soft side) to the next stroke (extension / soft side), set the damping force adjusting valve to position B at the current stroke.
When switching to the current stroke (shrink / soft side) to the next stroke (extension / hard side), set the damping force adjusting valve to position C at the current stroke.
By switching to, it is possible to switch to a desired damping force characteristic when the stroke changes from the current stroke to the next stroke. When the desired damping force characteristic of the next stroke is obtained at the current damping force adjusting valve position, the damping force characteristic is not switched as a matter of course.

A case as an example will be described with circles added to the symbols in FIG. For example, when the damping force adjusting valve is at the position B in the contracting stroke at present, the damping force characteristic is B ₂ (soft characteristic), and when the damping force adjusting valve is switched to the position C, the damping force characteristic is C ₂ (soft characteristic). ), And then, when changing from the current stroke (contraction stroke) to the next stroke (extension stroke), the damping force adjusting valve is in position C, so the damping force characteristic is C
₁ (hard characteristic).

Utilizing the above control, for example, in order to reduce the impact at the time of riding over a road surface protrusion and to improve the rest after that, the damping force characteristic is passed over in a soft state, and then the damping force characteristic is passed over. When considering the control to make hard, first, the damping force characteristics of expansion and contraction pass over time at position B on the expansion side / soft-contraction side / soft side, and in the subsequent expansion stroke, the damping force characteristics of the next stroke are set. Select the extension side / soft-shrink side / hard position A to switch. If it opposes, the damping force characteristic will only switch from soft to soft in the extension stroke, and no shock will occur due to the switching. Then, in the next compression stroke, the desired damping force characteristic hardware is switched. If the position D is further selected and switched during this process, it is possible to switch to a state in which both expansion and contraction have hard damping force characteristics without being accompanied by a shock due to a sudden change in damping force. After that, when the vibration subsides and the expansion / contraction is changed to the position of the soft damping force characteristic, position D →
By sequentially switching the position C → the position B or the position D → the position A → the position B, the switching can be completed without the sudden change of the damping force.

In this way, the position of the damping force adjusting valve is set to 4
The damping force characteristics can be freely switched by selecting from one of the combinations. At this time, since the damping force adjusting valve is switched only to a similar damping force characteristic within one stroke, the damping force does not suddenly change at the time of switching and no impact occurs. Also, in the next stroke, the switching of the damping force characteristics of the hydraulic shock absorber 5 to different characteristics (from the hard side to the soft side or from the soft side to the hard side) changes the stroke direction of the operating rod to the next stroke. Since it can be performed before moving, that is, before the stroke speed becomes zero, the damping force generation mechanism that generates the damping force in the next stroke does not generate the damping force in the current stage at the time of switching, No shock will occur due to force switching. Furthermore, there is no delay in switching the damping force, and the occurrence of impact can be reliably prevented.

Next, the second control method by the controller 8 will be described with reference to FIG. Note that FIG. 12 is created according to the same rules as in FIG. In this control method,
As shown in FIG. 12, in addition to switching the damping force control valve during one stroke (expansion or contraction stroke) to one of the four positions having the same damping force characteristics within that stroke, It is possible to switch from hard characteristics to soft characteristics.
That is, the soft characteristic is switched to the soft characteristic, the hard characteristic is switched to the hard characteristic, and the hard characteristic is switched to the soft characteristic.

According to this control method, it is possible to freely change the damping force characteristic as in the case of the first control method, and in addition, in addition to the current state, the change from the hard characteristic to the soft characteristic is performed. Can be done freely. In this case, the damping force characteristic is switched during the stroke of the operating rod, but since the switching is from the hard side to the soft side, the impact of the shock at the time of switching is slight.

Next, as a third control method, a case will be described with reference to FIG. 13 in which a hydraulic shock absorber having three damping force adjusting valves, as shown in FIGS. 4 and 8, is used. Note that FIG. 13 is created according to the same rules as in FIG. In this control method, as shown in FIG. 13, one stroke (expansion or contraction stroke) is performed as in the second control method.
Switching of damping force adjusting valve in the three positions (four positions in the second control method) are switched to positions having similar damping force characteristics within the stroke, and switching from hard characteristics to soft characteristics And are possible. That is, the soft characteristic is switched to the soft characteristic and the hard characteristic is switched to the soft characteristic.

According to this control method, the damping force characteristics can be freely switched as in the second control method. However, in this case, when the switching of the damping force characteristics from the current stroke to the next stroke is to switch to the same damping force characteristics, by switching to a different damping force characteristic in the current stroke, the original damping force characteristics are changed in the next stroke. You need to turn it back.
Therefore, for example, when switching from the current stroke (extension / hard side) to the next stroke (contraction / hard side), the damping force adjusting valve is switched to position C at the current stroke, and once the current stroke is set to the soft side, the next stroke is performed. It will be switched to (shrink / hard side).

As the third control method, as shown in FIGS. 4 and 8, the damping force adjusting valve is set to the soft side on the expansion side and the hard side on the contraction side (position A), and similarly the soft-soft (position B) and the hard side. -While it has been described as a control for taking three positions of soft (position C), instead of soft-soft at position B, a hydraulic shock absorber having a damping force characteristic of expansion hard at position B-hard at position B is used. It is also possible to perform the control method of No. 3. However, in this case, since it is not possible to maintain the current stroke (stretch / soft) from the next stroke (shrink / soft) without switching, it is often considered that both stretch and shrink are soft characteristics in general driving. This is not the preferred control method.

Although the above control is damping control for vertical vibration, it may be used in combination with posture control such as anti-roll and anti-dive for switching the damping force for maintaining the posture of the vehicle body. In this case, when both controls are performed at the same time and the controls are inconsistent with each other (for example, when one requires a soft characteristic and the other requires a hard characteristic), either one of them is controlled depending on the situation. Should be prioritized.

Further, the same damping force characteristic in one stroke which is switched by the damping force adjusting valve, for example, the soft characteristic A ₁ on the extension side and the soft characteristic B ₁ do not have to be exactly the same damping force characteristic, and are the same. Hard characteristic C ₁ during the process,
As long as the damping force is lower than that of D ₁ , the soft characteristic A ₁ and the soft characteristic B ₁ may have different damping force characteristics to some extent. The same applies to the hard characteristics C ₁ and D ₁ on the expansion side, the soft characteristics B ₂ and C ₂ on the contraction side, and the hard characteristics A ₁ and D ₁ on the contraction side.

[0075]

According to the suspension control device of the present invention, the damping force characteristic of the damping force adjusting type hydraulic shock absorber has the same damping force characteristic even when switching the damping force during one stroke of expansion or contraction. Since the change from the hard side to the soft side is performed, the shock caused by a sudden change in the damping force at the time of change is small, and then the desired damping in the next stroke is performed before the stroke is changed and the stroke is changed to the next stroke. Since it is possible to switch to the force characteristic, there is no impact due to switching to the desired damping force characteristic in the next stroke. In this way, it is possible to prevent a shock from occurring due to a sudden change in the damping force when switching the damping force characteristics.

[Brief description of drawings]

FIG. 1 is a diagram showing the overall configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing a main part of an example of a damping force adjustable hydraulic shock absorber of the device of FIG.

FIG. 3 is a view showing a main part of another example of the damping force adjusting hydraulic shock absorber of the apparatus of FIG. 1.

FIG. 4 is a view showing a main part of still another example of the damping force adjusting hydraulic shock absorber of the apparatus of FIG. 1.

5 is a vertical cross-sectional view of a main part of an example of the damping force adjusting hydraulic shock absorber of FIG. 2. FIG.

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

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

8 is a vertical cross-sectional view of a main part of an example of the damping force adjusting hydraulic shock absorber of FIG.

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

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

11 is a diagram showing an example of a control method by a controller of the apparatus of FIG.

12 is a diagram showing another example of the control method by the controller of the apparatus of FIG.

13 is a diagram showing still another example of the control method by the controller of the apparatus of FIG.

[Explanation of symbols]

 1 Suspension control device 2 Vehicle body 3 Wheel 5 Damping force adjusting hydraulic shock absorber 8 Controller (control device) 10a, 20 Hydraulic circuit (damping force adjusting means) 19 Actuator (damping force adjusting means)

Claims (2)

[Claims] 1. A suspension control in which a damping force characteristic of a damping force adjusting hydraulic shock absorber interposed between a wheel side and a vehicle body side of a vehicle suspension device is appropriately switched by a control device according to a running situation. In the device, the damping force adjusting type hydraulic shock absorber has at least three combinations of damping force characteristics, soft on the extension side and soft on the contraction side, soft on the extension side and hard on the contraction side, and hard on the extension side and soft on the contraction side. A damping force adjusting means that is selectively switchable from among the damping force adjusting hydraulic shock absorbers. The damping force adjusting means is made to perform non-switching of the damping force characteristic or switching to a similar damping force characteristic during the one stroke so as to be a desired one of the softening. A suspension control device that outputs a control signal that 2. A suspension control in which a damping force characteristic of a damping force adjusting hydraulic shock absorber interposed between a wheel side and a vehicle body side of a vehicle suspension device is appropriately switched by a control device according to a running situation. In the device, the damping force adjusting type hydraulic shock absorber has at least three combinations of damping force characteristics, soft on the extension side and soft on the contraction side, soft on the extension side and hard on the contraction side, and hard on the extension side and soft on the contraction side. A damping force adjusting means that is selectively switchable from among the damping force adjusting hydraulic shock absorbers. In order to obtain the desired one of the softening, the damping force characteristic is not switched during the one stroke, the damping force characteristic is switched to the same, or the hard side is switched to the soft side. A suspension control device which outputs a control signal for causing the damping force adjusting means to perform switching.