JPH048245B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an active control type suspension device that suppresses vibration and/or rocking of a vehicle body by actively controlling the suspension.

[Conventional technology]

As a conventional active control type suspension device, there is one disclosed in Japanese Patent Laid-Open No. 79438/1983 (first prior art example).

As shown in FIG. 2a, the cylinder tube 1a of a double-acting hydraulic cylinder 1 is attached to a wheel side member, the piston rod 1b of this hydraulic cylinder 1 is attached to a vehicle body side member 2, and as shown in FIG. In addition, the cylinder tube 1a and the vehicle body side member 2
A coil spring 3 is installed between the coil spring 3 to support the vehicle body side member 2, and to support both pressure chambers A and B of the hydraulic cylinder 1.
is connected to a hydraulic power source 5 via a center bypass type electromagnetic directional control valve 4. An orifice 6 is connected between both pressure chambers A and B of the hydraulic cylinder 1.

Another example is "Autocar", published in the UK on September 10, 1983.
(published by Haymarket Publishing Ltd.) (second conventional example).

This cylinder tube 1 of a single-acting hydraulic cylinder 1 has a schematic configuration shown in FIG. 2b.
a is attached to the vehicle body side member 2, a piston rod 1b is attached to the wheel side member, and the vehicle body side member 2 is supported by a gas spring 7, and the gas spring 7 and the hydraulic cylinder 1 pressure chamber through an orifice 8.

The electromagnetic directional control valves 4 of the first conventional example and the second conventional example are detected by a stroke sensor 9 that detects the relative displacement (stroke) between the unsprung portion and the unsprung portion, and the control device 10 detects stroke fluctuations. It is controlled to be small.

As schematically shown in Fig. 3, the control method in this case is that when the steering wheel is turned, the accelerator pedal is depressed, the brake pedal is depressed, etc. that cause the vehicle to change its attitude (block), In response to this, lateral acceleration or longitudinal acceleration occurs in the vehicle body (block), which causes posture changes such as rolling and pitching in the vehicle body (block). In this way, when a change in attitude occurs in the vehicle body, this is detected by the stroke sensor 9 (block), and the detected stroke value and the preset target stroke (zero in normal conditions without a change in the attitude of the vehicle) and control the actuator 1 by controlling the electromagnetic directional control valve 4 according to the deviation (block),
Thereby, control is performed to reduce changes in the posture of the vehicle body.

[Problem that the invention seeks to solve]

However, in the above-mentioned conventional active control suspension device, in the first conventional example,
When controlling the attitude of a vehicle, hydraulic oil is also directly supplied to the drain side through the orifice, which poses a problem in that power loss for driving the hydraulic power source becomes large.

In addition, since both the first conventional example and the second conventional example generate damping force using an orifice with fixed characteristics, the excitation force from under the spring is input to the vehicle body through the orifice, resulting in insufficient improvement in ride comfort. It was hot.

Therefore, this invention has been made by focusing on the above-mentioned conventional problems.The present invention is designed to reduce the vibration input to both the upper and lower pressure chambers of the fluid pressure cylinder by directly operating a switching valve due to the vibration input to the vehicle body. The purpose of this invention is to solve the above problems by controlling the pressure.

[Means for solving problems]

In order to solve the above problems, the present invention provides a double-acting fluid pressure cylinder that is interposed between a sprung mass and a sprung mass of a vehicle to absorb vibration input from the wheel side to the vehicle body side, and The piston rod of the fluid pressure cylinder is attached to the vehicle body via an elastic body, and includes a switching valve that controls the pressure in both the upper and lower pressure chambers of the cylinder, and a control device that controls the switching valve, and the piston rod of the fluid pressure cylinder is attached to the vehicle body through an elastic body.
One of the spool side and the valve housing side of the switching valve is directly connected to the piston rod of the fluid pressure cylinder and the other vehicle body side, respectively, and the vibration input is transmitted to the vehicle body via the fluid pressure cylinder. It is characterized in that the switching valve is directly controlled.

[Effect]

This invention is a double-acting type cylinder that is installed between the sprung and unsprung portions of a vehicle to absorb vibration input from the wheels to the vehicle body. allows a small movement of the piston rod due to the vibration input transmitted to the hydraulic cylinder of the piston rod, and transmits this small movement of the piston rod to the spool or valve housing of the switching valve, thereby switching the switching valve to absorb the vibration input. By controlling the pressure in both pressure chambers of the hydraulic cylinder so as to absorb vibration input, vibration input is reliably absorbed.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a sectional view showing an embodiment of the present invention.

In the figure, reference numeral 1 denotes a hydraulic cylinder as a fluid pressure cylinder interposed between an unsprung portion and an unsprung portion of a vehicle, and its cylinder tube 1a is rotatably attached to a wheel side member (not shown). Along with being there,
The upper end of the piston rod 1b is attached to the vehicle body member 2 via an elastic body 11, and a coil spring 3 is interposed between the cylinder tube 1a and the vehicle body member 2. Here, the cylinder tube 1a has a piston rod 1 extending therein.
The piston 1c attached to the lower end of the piston 1c defines an upper pressure chamber A and a lower pressure chamber B, and is configured as a double-acting type.

The elastic body 11 is, for example, a rubber elastic cylinder 11a.
and a metal disk 11 glued to its upper and lower surfaces.
b, 11c, and the peripheral edge of the through hole 2a formed in the vehicle body side member 2 is fitted into the annular slit 11d formed in the axial center of the elastic cylinder 11a. is installed on. Then, the small diameter end 1d of the piston rod 1b is fitted into the elastic cylinder 11a of the elastic body 11, and the nut 12 is screwed into the threaded part 1e connected upward to the small diameter end 1d of the piston rod 1b and tightened. It is fixed by.

Reference numeral 13 denotes a directional control valve, which includes a cylindrical valve housing 14 and a cylindrical sleeve 15 slidably but unrotatably disposed within the valve housing 14.
and a spool 16 slidably disposed within this sleeve 15. in this case,
The valve housing 14 has an input port 14a to which a hydraulic pipe 18 connected to the hydraulic oil supply side of the hydraulic power source 17 is connected, and an output port 14b to which a hydraulic pipe 19 connected to the drain side of the hydraulic power source 17 is connected. ，
14c, and pressure chambers B and A of the hydraulic cylinder 1.
Input/output ports 14d and 14e are provided, which are connected via hydraulic pipes 20 and 21, respectively.

The sleeve 15 also has oil holes 15a facing each port 14a to 14e of the valve housing 14.
- 15e are bored, and a female thread 15f is formed at the upper end, into which a screw shaft 23 fixed to the rotating shaft of a step motor 22 as a sleeve moving means fixed to the upper end of the valve housing 14 is screwed. are combined.

Additionally, the spool 16 includes a valve housing 14.
Input port 14a and output port 14b, 14
Lands 16a to 16c are formed opposite to the land 16c, and the tip 1f of the piston rod 1b is in contact with the lower end surface of the land 16c, and a pressing spring 24 is provided between the upper end surface of the land 16b and the sleeve 15. is interposed, thereby urging the spool 16 toward the tip 1f of the piston rod 1b.

Reference numeral 25 is a stroke sensor that detects the stroke (displacement amount) of the unsprung part with respect to the sprung part, and is composed of a detection part 25a fixed to the cylinder tube 1a of the hydraulic cylinder 1 and an actuator 25b attached to the vehicle body side member 2. The detecting section 25a is composed of, for example, a potentiometer, and outputs an electric signal according to the stroke to the control device 26.

The control device 26 is supplied with the detection signals of the stroke sensor 25, compares these with a preset target stroke, calculates a deviation between the two, and outputs a control signal CS to the step motor 22 in accordance with this. That is, when the actual stroke detected by the stroke sensor 25 is shorter than the target stroke, it is determined that the vehicle height at that wheel position is decreasing, and the step motor 2 is adjusted so that the vehicle height reaches the target vehicle height.
For example, by rotating the sleeve 15 in the normal direction and raising the sleeve 15 by a predetermined stroke from the neutral position shown in FIG.
This increases the pressure in cylinder tube 1.
a is lowered to make the actual stroke match the target stroke, and conversely, when the actual stroke detected by the stroke sensor 25 is longer than the target stroke, it is determined that the vehicle height at that wheel position is rising. Then, the step motor 22 is reversed to lower the sleeve 15 a predetermined distance from the neutral position, supplying hydraulic oil to the upper pressure chamber A of the hydraulic cylinder 1 and increasing the pressure in the pressure chamber A, thereby increasing the pressure in the cylinder tube 1a. is controlled so that the actual stroke is positioned at the target stroke.

Next, the operation will be explained. Now, it is assumed that the vehicle is traveling straight at a constant speed on a flat, good road, and there is almost no vibration input to the wheels from the road surface. Assuming that no posture changes such as bounce have occurred, in this state, the stroke of the unsprung portion relative to the sprung portion approximately matches the target stroke,
The control device 26 does not output the control signal CS,
The step motor 22 is stopped and the sleeve 1
5 is held in the neutral position, and its oil passage holes 15a~
15e represents each port 14a to 1 of the valve housing 14
It is facing 6e. Furthermore, since there is no vibration input transmitted from the wheel side to the vehicle body side member 2 via the hydraulic cylinder 1, no external force acting on the piston rod 1b to move it in the vertical direction is applied to the elastic body 11. Therefore, it is held at a neutral position with respect to the vehicle body side member 2. Therefore, the spool 16 of the directional control valve 13 is held in the neutral position, and its lands 16a, 16b, 16c
Input port 14a and output port 14b, 1 connected to hydraulic source 17 of valve housing 14 by
4c is occluded. As a result, the pressures in both pressure chambers A and B of the hydraulic cylinder 1 are maintained at the same predetermined value.

In this state, when an excitation force generated by riding over a convex portion of the road surface is input to the wheel, the hydraulic cylinder 1 is pressed upward. At this time, since both pressure chambers A and B are in a blocked state, the piston rod 1b is pressed upward via the piston 1c, and the elastic body 11 is displaced in accordance with the pressing force, causing the piston rod 1b to move upward. . This movement of the piston rod 1b causes the spool 16 to rise from the neutral position to the upper offset position against the pressure spring 24, thereby causing the input port 14a to become the input/output port 14e and the output port 14b to become the input/output port 14d. will be connected to each other. Therefore, the hydraulic oil from the hydraulic source 17 is transferred to the hydraulic piping 18,
The hydraulic oil in the lower pressure chamber B is supplied to the upper pressure chamber A of the hydraulic cylinder 1 via the directional switching valve 13 and the hydraulic piping 21, and the hydraulic oil in the lower pressure chamber B is supplied to the hydraulic piping 20 and the directional switching valve 1.
3 and the hydraulic piping 19 to the drain side of the hydraulic power source 17, whereby the pressure in the pressure chamber A increases and the pressure in the pressure chamber B decreases.
As a result, the cylinder tube 1a rises relative to the piston rod 1b, and the pressing force from the hydraulic cylinder 1 that presses the vehicle body upward via the piston rod 1b is reduced.

Conversely, when the wheel engages with a road surface depression and a vibration input is input that causes the hydraulic cylinder 1 to displace downward, the piston rod 1b descends and the spool 1
6 is also lowered from the neutral position to the lower offset position, and accordingly, the input port 14a becomes the input/output port 14d, and the output port 14c becomes the input/output port 1.
4e, respectively, and thereby the hydraulic cylinder 1
The pressure in the upper pressure chamber A decreases and the pressure in the lower pressure chamber B increases. As a result, the cylinder tube 1a is lowered relative to the piston rod 1b, reducing the vibration input that lowers the vehicle body.

In this way, vibration input from the road surface to the wheels can be absorbed without time delay, and vibration of the vehicle body can be reduced to improve ride comfort.

Furthermore, when the vehicle moves from a straight-ahead running state to a right (or left) turn state by operating the steering wheel (not shown), the vehicle body rolls, and the vehicle height at the front left wheel and rear left wheel positions decreases. As the vehicle height decreases, the vehicle height at the front right wheel and rear right wheel positions increases. In this way, when a change in the posture of the vehicle body occurs, this is detected by the stroke sensor 25, and the detection signal is supplied to the control device 26, so that the control device 26 can control the suspension device's steps at the front left wheel and rear left wheel positions. For the motor 22, a control signal CS that commands reverse rotation is sent to the motor 22.
A control signal CS instructing forward rotation is output to the step motors 22 of the suspension device at the front right wheel and rear right wheel positions, respectively. Therefore,
In the suspension device on the left side of the vehicle, the sleeve 15 of the directional control valve 13 rises from the neutral position to connect the input port 14a to the input/output port 14d.
Then, the output port 14c is communicated with the input/output port 14e, and the pressure in the upper pressure chamber A of the hydraulic cylinder 1 is lowered, and the pressure in the lower pressure chamber B is increased, causing the piston rod 1b to rise. Raise the left side of. Conversely, in the suspension device on the right side of the vehicle, the directional control valve 13
The sleeve 15 is lowered from the neutral position to communicate the input port 14a with the input/output port 14e and the output port 14b with the input/output port 14d, thereby increasing the pressure in the upper pressure chamber A of the hydraulic cylinder 1 and increasing the pressure in the lower pressure chamber A. The pressure in the pressure chamber B is lowered, thereby lowering the piston rod 1b and lowering the right side of the vehicle body to exert an anti-roll effect.

Similarly, if the vehicle body becomes tight, such as when the brake pedal is depressed and the vehicle body experiences a so-called nose dive phenomenon, or when the accelerator pedal is depressed and the vehicle body causes a so-called scat phenomenon, the vehicle height may be lowered. The pressure in the upper pressure chamber A of the hydraulic cylinder 1 of the suspension device on the side that has been raised decreases, and the pressure in the lower pressure chamber B increases, raising the vehicle body. The pressure in the upper pressure chamber A increases, the pressure in the lower pressure chamber B decreases, and the vehicle body is lowered to produce an anti-pitch effect. Also, when the vehicle bounces, such as when driving on an undulating road surface, the pressure in the upper pressure chamber A of the hydraulic cylinder 1 of all suspension devices increases ( or decrease)
However, the pressure in lower pressure chamber B decreases (or increases),
It can exhibit an anti-bounce effect.

In this way, changes in the posture of the vehicle body due to roll, pitch, bounce, etc. are much gentler than the vibration input from the road surface, so the control device 26 controls the sleeve 15 of the directional control valve 13.
can be easily and reliably suppressed by displacing it from its neutral position.

In addition, in the above embodiment, a case has been described in which the hydraulic cylinder 1 is applied as the fluid pressure cylinder, but the invention is not limited to this, and a fluid pressure cylinder operated by other fluid pressure such as air pressure may also be used. Of course, it can be applied.

Further, in the above embodiment, a case has been described in which the spool 16 of the switching valve 13 is displaced according to the amount of displacement of the piston rod 1b, but the spool 16 is fixed to the vehicle body side member 2, and the valve housing A hydraulic pipe 21, which connects the piston rod 1b to the pressure chambers A and B,
Even if 22 are connected in an inverse relationship, the same effect as in the above embodiment can be obtained.

Further, in the above embodiment, the case where a spool valve is applied as the switching valve is explained, but the switching valve is not limited to this, and a rotary valve can also be applied. In this case, the displacement of the piston rod 1b The rotational spool or valve housing of the switching valve may be rotated by converting the amount into a rotational displacement amount.

Furthermore, the means for moving the sleeve is not limited to the step motor 22, but a linear drive mechanism such as an electromagnetic solenoid may be used.

Further, in the above embodiment, a case was described in which a stroke sensor made of a potentiometer was applied as a relative displacement detection means for detecting relative displacement between an unsprung part and an unsprung part, but the invention is not limited to this. Of course, any relative displacement detection means such as a differential transformer can be applied.

〔Effect of the invention〕

As explained above, according to the present invention, the vibration input input to the fluid pressure cylinder interposed between the unsprung portion and the unsprung portion of the vehicle causes the piston rod to act directly on the switching valve, thereby reducing the vibration input. Because the configuration controls the pressure in the upper and lower pressure chambers of the fluid pressure cylinder, it is possible to omit the orifice that was conventionally required to absorb vibration input, eliminating power loss from differential oil flowing to the drain through the orifice, and improving the car body. In addition to efficiently controlling transmission to the vehicle and controlling changes in vehicle body posture, the vibration input directly acts on the switching valve, eliminating the need for attached equipment such as a load sensor that detects the vibration input and its control circuit. This has the effect of simplifying the process and improving responsiveness.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIGS. 2a and 2b are configuration diagrams of a conventional device, and FIG. 3 is an explanatory diagram for explaining the control method thereof. 1...Hydraulic cylinder (fluid pressure cylinder), 1a
...Cylinder tube, 1b...Piston rod, 1c...Piston, A...Upper pressure chamber, B...
lower pressure chamber, 2... vehicle body side member, 11... elastic body,
13... Directional switching valve, 14... Valve housing, 1
5... Sleeve, 16... Spool, 22... Step motor (sleeve moving means), 25... Stroke sensor, 26... Control device.

Claims (1)

[Scope of Claims] 1. A double-acting fluid pressure cylinder that is interposed between the sprung mass and the unsprung mass of a vehicle to absorb vibration input from the wheel side to the vehicle body side, and both upper and lower pressure chambers of the fluid pressure cylinder. a switching valve for controlling the pressure of the switching valve; and a control device for controlling the switching valve; the piston rod of the fluid pressure cylinder is attached to the vehicle body via an elastic body; One of the switching valves is directly connected to the piston rod of the fluid pressure cylinder, and the other is directly connected to the vehicle body, and the switching valve is directly controlled in response to vibration input transmitted to the vehicle body via the fluid pressure cylinder. Actively controlled suspension device. 2. The control device has relative displacement detection means for detecting relative displacement between the sprung mass and the unsprung mass, and uses the detection signal of the relative displacement detection means to suppress posture changes such as roll, pitch, and bounce of the vehicle body. 2. An actively controlled suspension device according to claim 1, wherein said switching valve is controlled. 3 The switching valve is comprised of an axially slidable sleeve interposed between a spool and a valve housing, and a sleeve moving means for moving the sleeve in response to a control signal from a control device. An actively controlled suspension device according to claim 1 or 2.