JP3172881B2 - Active suspension device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an active suspension system which is most suitable for use in a hydraulic suspension system as a vehicle suspension system.

[0002]

2. Description of the Related Art There have been various proposals for an active suspension device as a hydraulic suspension system as a suspension system of a vehicle. However, basically, the active suspension device is disposed in each of four parts of a vehicle and an upper end thereof is located on a vehicle body side. The hydraulic pressure from a hydraulic source is supplied to each hydraulic cylinder, which is connected and the lower end is connected to the axle side, through a control valve, and the hydraulic pressure from each hydraulic cylinder is discharged to the tank through the control valve, so that the hydraulic pressure is reduced. The cylinder pressure in the cylinder is controlled to be high or low.

The control valve receives detection signals from various sensors disposed on the body of the vehicle or the like to detect the state of the vehicle, and processes the signals based on preset positions. This is controlled by a command signal from a controller that outputs the control valve.

Therefore, according to this conventional active suspension device, the control valve is appropriately controlled based on the traveling road surface condition of the vehicle to control the cylinder pressure in each hydraulic cylinder, thereby increasing or decreasing the cylinder pressure in each of the four wheels of the vehicle. , The vehicle attitude can be controlled according to the condition of the traveling road surface, and the riding comfort and steering stability of the vehicle can be improved.

[0005]

However, in the above-mentioned conventional active suspension device, one hydraulic source is provided to each hydraulic cylinder for supporting the vehicle load provided in each part of the four wheels. That and each of these hydraulics
The cylinder is a single-acting hydraulic series without a suspension spring.
Since it is configured to so that support the vehicle load as Sunda, becomes easier incurred is the following problem.

That is, since only one hydraulic source is provided to each hydraulic cylinder, the amount of oil required for performing a predetermined hydraulic control is increased. Therefore, a large hydraulic source is selected. As a result, the weight of the entire apparatus is increased and the mountability of the apparatus on a vehicle is deteriorated.

A single-acting type without a suspension spring
Supports vehicle load only by hydraulic pressure of hydraulic cylinder
Also becomes momentum pressure both control pressure when a large one is selected by the hydraulic pressure source from the fact that as, therefore, in particular,
In a hydraulic cylinder, a high sealing property is required, while a high pressure action on the seal increases the sliding resistance in the sealing portion, thereby deteriorating the slidability and causing a deterioration in ride quality.

Furthermore, in addition, depending truly hydraulic control format definitive the discharge side leading to the tank from a supply side and a control valve extending from the hydraulic source to the control valve, either in and from the hydraulic source be
The function to support the vehicle load only by the oil pressure by the pressure oil
As a matter of fact, a large hydraulic pump with high pressure and large discharge as a hydraulic source
And energy loss is more likely to be caused.

As a result, in the above-mentioned conventional active suspension device, inconveniences such as an increase in the weight of the entire device, deterioration in mountability in a vehicle, and deterioration in ride comfort and economy are likely to be caused. Become.

The present invention has been made in view of the above circumstances, and has as its object to increase the weight of the entire apparatus, to deteriorate the mountability on a vehicle, and to improve ride comfort and economy. SUMMARY OF THE INVENTION An object of the present invention is to provide an active suspension device which can be expected to improve its versatility without causing inconvenience such as deterioration of performance and the like, and which is optimal for use as a hydraulic suspension system as a suspension system of a vehicle.

[0011]

In order to achieve the above-mentioned object, a construction according to the present invention is provided by disposing a spring for supporting a vehicle load when the vehicle is empty, disposed on each of the four wheels of the vehicle, and having an upper end on the vehicle body side. And the lower end is connected to the axle side, and when the hydraulic pressure from the hydraulic pressure source is supplied via a control valve that operates based on the road surface conditions of the vehicle, the cylinder pressure on the extension side or the compression side is generated individually. Formed to
A double-acting hydraulic cylinder for active control is provided , and each hydraulic cylinder is supplied with hydraulic pressure from a respective hydraulic source via a respective supply path and a respective control valve, and the hydraulic pressure from the respective hydraulic cylinders is respectively The control valve and the respective discharge passages are configured to be discharged to the tank side, and the supply passage is provided with a check valve for preventing backflow in the supply passage and the discharge passage is provided with a damping valve. An accumulator via a valve is provided,
Further, a direction switching valve is provided in the discharge path, and the operation of the direction switching valve selectively enables communication between the discharge path and the supply path or between the discharge path and the tank.

The hydraulic power source, the control valve and the direction switching valve process detection signals from various sensors disposed on the vehicle body or the like for detecting the state of the vehicle based on predetermined positions and perform predetermined processing. It is assumed that each is controlled by a controller that outputs a command signal.

[0013] The hydraulic pressure source is used for a vehicle running engine .
It may be driven directly through a drive belt, but it can
Power is charged by the driving engine if it is
Driving through electric motor driven by vehicle battery
I'll do it like that.

[0014]

Therefore, it is possible to control each hydraulic cylinder in each part of the four wheels independently by the respective hydraulic pressure source, control valve, direction switching valve, etc., which has an effect on the traveling engine mounted on the vehicle. Not possible.

In controlling the cylinder pressure in the hydraulic cylinder, since a sprung load (vehicle load when the vehicle is idle, etc.) is supported by a spring attached to the hydraulic cylinder, a high pressure is not required to control the cylinder pressure. In addition to this, it is not necessary to generate a cylinder pressure in the hydraulic cylinder when the vehicle is stopped or when traveling straight on a good road.

Further, when the control valve is in a neutral position, which is a communication position, the control valve is configured to enable free communication between the supply side and the discharge side, thereby suppressing generation of a circuit load. It becomes possible.

Further, in the hydraulic pressure source, it is possible to generate the hydraulic pressure only when necessary and to generate the hydraulic pressure for the circuit loss.

As a result, it is possible to reduce the size of the hydraulic pressure source and to prevent the high hydraulic pressure from acting on the seals of the valves and cylinders in the circuit, thereby reducing friction and expecting control as set. Will be possible.

[0019]

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

As shown in FIG. 1, the active suspension apparatus according to one embodiment of the present invention is, in principle, disposed on each of four wheels (in the figure, T is a tire) of a vehicle (not shown). Control unit U.

Command signals from the electric motor driver D and the solenoid amplifier E are input to the control unit U, and command signals from the controller C are supplied to the electric motor driver D and the solenoid amplifier E, respectively. It is assumed that each signal is input.

The controller C includes vehicle sensors C1 and C2 disposed on the vehicle body B (see FIG. 2) for detecting the condition of the running vehicle, and the vehicle body B and the suspension arm A (the axle). It is assumed that a detection signal is input from a vehicle height sensor C3 or the like which detects the vehicle height and the like, and a signal obtained by processing the input signal based on a preset position is output to the controller C. Is output.

The control unit U is, as shown in FIG.
Hydraulic cylinder 1, hydraulic source 2, control valve 3, tank 4
The supply path 5 that connects the hydraulic pressure source 2 and the control valve 3 has a check valve 5a that prevents backflow in the supply path 5, and the control valve 3 and the tank 4 side. The discharge path 6 includes an accumulator 6b via a damping valve 6a. The discharge path 6 has a direction switching valve 7, and the discharge path 6 and the supply path are operated by the operation of the direction switching valve 7. 5 or a selected communication between the discharge path 6 and the tank 4 is enabled. That is, the direction switching valve 7 is unloaded.
Exhibits the function as a fail-safe valve.

The hydraulic oil from the hydraulic pressure source 2 is supplied to the extension side chamber 1a or the compression side chamber 1b of the hydraulic cylinder 1 via the control valve 3 and the oil passage 1c or 1d, and from the side chambers 1a and 1b. When the hydraulic pressure is released to the tank 4 side via the oil passage 1c or 1d and the control valve 3, the cylinder pressure in the hydraulic cylinder 1 is controlled to be high or low, whereby the vehicle height or the four wheels at each part of the four wheels of the vehicle is reduced. It is said that the supporting force can be adjusted in height to control the attitude of the vehicle.

In the control unit U, the hydraulic pressure source 2, the control valve 3, and the direction switching valve 7 are operated by a command signal from the controller C.

The hydraulic cylinder 1 is assumed to have a spring 1e according to the present invention, and the spring 1e is set to support a vehicle load when the vehicle is idle.

In this embodiment, the hydraulic cylinder 1 has a structure as shown in FIG. 3, and is formed as a so-called double cylinder type.

To explain a little, the piston 12 slidably accommodated in the cylinder 11 divides the expansion side chamber 1a and the compression side chamber 1b, and has a cylindrical shape by an outer cylinder 13 arranged on the outer periphery of the cylinder 11. It is assumed that a cap member 15 is disposed on the upper end side so that the passage 14 is formed, and a shaft sealing member 17 for inserting the piston rod 16 is disposed on the lower end side.

Then, an oil passage 1c is communicated with the extension side chamber 1a through a port 15a opened in the cap member 15,
A port 15b formed in the cap member 15, a communication hole 11a formed in the upper end of the cylinder 11, a communication passage 11b formed in the cylindrical passage 14, and a communication hole 11b formed in the lower end of the cylinder 11.
The oil passage 1d is communicated with the pressure side chamber 1b through the pressure passage.

On the other hand, a lower spring receiver 18 is held at the lower end of the piston rod 16, and an upper spring receiver 19 is held by the cap member 14.
9, the spring 1e is held.

As a result, in the hydraulic cylinder 1,
When the hydraulic pressure from the oil passage 1c is supplied to the extension side chamber 1a, the cylinder pressure on the extension side of the hydraulic cylinder 1 is increased, so that it is possible to counter the situation where the hydraulic cylinder 1 is about to be compressed. By supplying the oil pressure from the oil passage 1d to the compression side chamber 1b, the pressure side cylinder pressure in the hydraulic cylinder 1 is increased, and it is possible to counter the situation where the hydraulic cylinder 1 is about to be extended.

The hydraulic power source 2 is configured to suck hydraulic oil from the tank 4 and discharge the hydraulic oil to the supply passage 5, and in this embodiment, the hydraulic oil is supplied to the traveling engine of the vehicle.
Therefore, it is driven by the in-vehicle battery that is charged
It is set to be driven through the electric motor 2a .

When the control valve 3 is in the neutral position, which is a communication position, the supply path 5 and the discharge path 6, the extension side chamber 1a and the compression side chamber 1b in the hydraulic cylinder 1, and the free communication between them are possible. In this embodiment, specifically, it is formed as shown in FIG.

That is, the control valve 3 has a spool 32 slidably housed in a valve body 31, and springs 3a, 3b and plungers 3c, 3d are provided at both ends of the spool 32. It is said that it will be in contact.

The valve body 31 is connected to the oil passage 1
c, a port 31b communicating with the oil passage 1d, a port 31c communicating with the supply passage 5, and ports 31d and 31e communicating with the two discharge passages 6, respectively.
And an annular groove 3 communicating with the port 31c and facing the central land portion 32a of the spool 32.
1f and end lands 32b and 32c at both ends of the spool 32 in communication with the ports 31d and 31e, respectively.
And annular grooves 31g and 31h facing each other.

In this embodiment, when the spool 32 has the central land portion 32a formed to be shorter than the annular groove 31f opposed thereto, and the control valve 3 is in the neutral position as the communication position. As shown in the figure, the ports 31a and 31b can be communicated with each other, and the ports 31a and 31b and the port 31c can be connected to each other.
To enable communication with

When the spool 32 is at the neutral position, which is a communication position, the two end lands 32b and 32c open the opposed annular grooves 31g and 31h, respectively, so-called ports 3a and 3b.
It is set so that 1a and 31b can communicate with the ports 31d and 31e, respectively.

As a result, in the control valve 3, when the spool 32 is at the neutral position as shown in the figure, communication between the oil passages 1c and 1d, the supply passage 5, and the discharge passage 6 is enabled. At the same time, when the spool 32 moves rightward in the drawing due to the thrust of the plunger 3c, the oil passage 1c and the supply passage 5
And communication between the oil passage 1d and the discharge passage 6 becomes possible, and
When the spool 32 moves leftward in the drawing due to the thrust of the plunger 3d, the oil passage 1c and the discharge passage 6 and the oil passage 1d and the supply passage 5
Each communication becomes possible.

When the control valve 3 is at the neutral position, an annular groove 31f formed in the valve body 31 and a central land portion 3 formed in the spool 32 are formed.
It is not necessary to ensure a so-called sealing property between the control valve 3a and the second valve 2a. Therefore, there is an advantage that a high precision control is not required in forming the control valve 3.

Damping valve 6a and accumulator 6b
Are the same as those conventionally provided as this type, and are configured to operate when the hydraulic cylinder 1 expands and contracts to cause the hydraulic cylinder 1 to exhibit a shock absorber function.

The directional control valve 7 is configured to function as a so-called fail-safe valve. In this embodiment, as shown in FIG. 5, the directional control valve 7 is formed in the form of a three-port electromagnetic directional control valve. ing.

That is, the directional control valve 7 is provided with a solenoid 7
a poppet 72 slidably housed in a valve body 71 connected to the valve body 71. A spring 7b is provided adjacent to a rear end of the poppet 72 which is the left end in the drawing. The plunger 7c protruding from the solenoid 7a is brought into contact with the other end, which is the right end.

The valve body 71 has a port 71a communicating with the discharge path 6 and a port 71b communicating with the discharge path 6 on the tank 4 side, and has a port 71c communicating with the supply path 5, and It has a chamber 71d for accommodating the spring 7b while communicating with the inflow port 71a, and has an annular seat portion 71e adjacent to the poppet portion 72a of the poppet 72 facing the poppet 72.

Further, the valve body 71 has an annular groove 71f communicating with the port 71b, and the land 72b of the poppet 72 is set to face the annular groove 71f.

As long as there is no acting force from the plunger 7c, the poppet 72 is
b, the poppet portion 72a is adjacent to the opposed annular seat portion 71e to prevent the flow of hydraulic oil in the portion, and the land portion 72b is The groove 71f is positioned so as to open, so that the oil pressure from the supply path 5 can be released to the tank 4 side.

As a result, in the directional control valve 7, when the solenoid 7a is energized, the plunger 7c causes the poppet 72 to move.
Is retracted so as to move to the left in the drawing, the poppet portion 72a separates from the annular seat portion 71d, enabling the flow of hydraulic oil in the portion and the land portion 72b.
Will close the annular groove 71f, and at this time, the hydraulic pressure from the discharge path 6 will be released to the tank 4 side.

Next, various operations in the hydraulic circuit formed as described above will be described. In the present invention, it is premised that the control units U in each part of the four wheels of the vehicle operate independently. is there.

First, during normal operation where control of the cylinder pressure in the hydraulic cylinder 1 is not required, the direction switching valve 7
, The power supply to the solenoid 7a is released, and the control valve 3 is also in the neutral position in the inoperative state.

Therefore, the hydraulic oil from the hydraulic power source 2 driven by the command signal from the controller C is drained to the tank 4 via the directional control valve 7, while the extension side chamber 1a of the hydraulic cylinder 1 The pressure side chamber 1b is connected to the accumulator 6b via the control valve 3 and the accumulator 6b via the damping valve 6a.

At this time, since the spring 1e provided in the hydraulic cylinder 1 bears the sprung load of the vehicle, the hydraulic cylinder 1 does not need to generate the cylinder pressure.

Therefore, during normal operation, no load acts on the hydraulic power source 2 and the control unit U serving as the hydraulic circuit is not operated.
In this case, unnecessary power consumption can be avoided.

Next, when the vehicle height is adjusted, various changes in the vehicle height, for example, a decrease in the vehicle height, are detected by various sensors such as a vehicle height sensor C3 and other sensors C1 and C2. The value is input to the controller C, and the controller C
First, the solenoid 7a in the direction switching valve 7 is excited, and a predetermined operation is induced in the control valve 3.

As a result, the hydraulic oil from the hydraulic power source 2 is guided to the hydraulic cylinder 1 via the supply passage 5, and at this time, the control valve 3 is moved, for example, rightward in the drawing. When the switching is performed, the hydraulic oil from the supply path 5 is supplied to the extension side chamber 1a of the hydraulic cylinder 1.

Therefore, in the hydraulic cylinder 1, the cylinder pressure in the extension side chamber 1a is increased so as to restore the lowered vehicle height and to balance the load causing the vehicle height reduction, thereby preventing the vehicle height change. Will be done.

At this time, the hydraulic oil from the pressure side chamber 1b is discharged to the tank 4 via the control valve 3 and the direction switching valve 7.

When controlling the posture, for example,
When the cylinder pressure of the hydraulic cylinder 1 that is about to be contracted by a roll or the like is increased as in the above-described vehicle height adjustment, and the cylinder pressure of the opposite hydraulic cylinder 1 that is about to be extended by a roll or the like is adjusted for the vehicle height. So as to descend.

As a result, the contraction of the hydraulic cylinder 1 that is about to contract is prevented, and the extension of the hydraulic cylinder 1 that is about to extend is prevented.
A change in the vehicle body posture due to a roll or the like is effectively prevented.

Further, when the ride comfort is controlled, it is possible to control each of the frequencies near the sprung resonance frequency and the unsprung resonance frequency, and when the frequency is higher.

That is, when the resonance frequency is around the sprung resonance frequency and the unsprung resonance frequency, the riding comfort can be controlled by controlling the cylinder pressure in the hydraulic cylinder 1 as in the case of the attitude control.

At this time, since the spring 1e bears most of the sprung load, the spring constant of the rubber bush provided at the connection between the upper and lower ends of the hydraulic cylinder 1 and the vehicle body B or the axle A can be set lower. become.

As a result, it is possible to reduce the transmission of vibration in the high frequency range, and the riding comfort at about the unsprung resonance frequency or higher is improved.

Further, since the hydraulic cylinder 1 has no spring element, responsiveness for controlling the resonance frequency to around the unsprung resonance frequency can be ensured, so that the ride comfort can be controlled to around the unsprung resonance frequency.

When the frequency is equal to or higher than the unsprung resonance frequency, the control valve 3 does not respond, that is, does not operate. At this time, the control valve 3 is in the neutral position and the port 31c is connected to the ports 31d and 31e. In communication,
The extension side chamber 1a and the compression side chamber 1b of the hydraulic cylinder 1 are in communication.

As a result, the hydraulic cylinder 1 enters a so-called free state and does not transmit vibration.
Since almost no neutral pressure is generated in the hydraulic cylinder 1, sliding resistance at the seal portion is reduced, and ride comfort control at a frequency equal to or higher than the unsprung resonance frequency becomes possible.

In the fail-safe state, that is, when an abnormality occurs in the electric system, the power supply to the solenoid 7a of the directional control valve 7 is stopped, and the control valve 3 is also maintained at the so-called neutral position of the inoperative state. You.

As a result, as in the case of the normal operation described above, the hydraulic cylinder 1 forms a closed circuit with the accumulator 6b via the control valve 3 but via the damping valve 6a. At this time, the pressure in the closed circuit is maintained as a pressure necessary to maintain a predetermined vehicle height.

Further, even in the fail-safe state in which a failure has occurred in the hydraulic system, since the body load is borne by the spring 1e, the vehicle height is not significantly reduced, and the vehicle travels. Enable.

When the vehicle is parked or stopped, discharge of hydraulic oil from the hydraulic power source 2 is stopped by turning off the ignition switch, and the control valve 3 and the direction switching valve 7 are in a so-called shut-off state.
Since the hydraulic oil is prevented from flowing out to the tank 4 through the discharge path 6, the hydraulic pressure for preventing the contraction of the hydraulic cylinder 1 is maintained, and the decrease in the vehicle height is prevented.

Since the load on the vehicle body is basically held by the spring 1e, the vehicle height does not decrease even if the vehicle is parked and stopped for a long time.

In the above embodiment, the control valve 3 is actuated by energizing the solenoid. Alternatively, the control valve 3 may be operated by another power source. Of course.

[0071]

As described above, according to the present invention, the control units provided at the respective four-wheel portions of the vehicle are configured to operate, respectively. Not only do not cause inconveniences such as an increase in the weight of the entire device and deterioration in mountability in a vehicle, and in riding comfort and economy, but also when the vehicle is stopped or traveling straight on a good road. Since the sprung load can be borne by the spring attached to the cylinder, it is not necessary to always maintain the cylinder pressure at a high pressure in the cylinder, and when the cylinder pressure control is not required, such as when the vehicle is stopped, the hydraulic pressure may be reduced. At the source, only the hydraulic pressure of the circuit loss can be generated, and therefore the neutral pressure can be made very small, and the control pressure required to generate the same cylinder pressure as before Half of it is possible to below.

When the input vibration from the road surface is high-frequency vibration, the control valve is switched to the communication position, whereby the extension side chamber and the compression side chamber of the cylinder communicate with each other, and the high frequency vibration is not transmitted to the cylinder. It is possible to suppress even a transmitted signal to a very small one.

On the other hand, since the so-called neutral control oil pressure is very small, the sliding resistance in each valve section such as the control valve can be suppressed to a small value, so that the circuit can operate smoothly.

Since the control oil pressure at the time of neutral is substantially zero, if the same maximum supply oil pressure as in the prior art is secured, the control oil pressure for controlling the cylinder pressure may be doubled. Will be possible.

Further, since there is no spring term in the system, the response of pressure control can be improved.

Further, even if the vibration isolating rubber is provided in the cylinder, it is possible to prevent the spring load from acting on the vibration isolating rubber, and it is possible to perform the vibration isolating using the vibration isolating rubber efficiently.

Further, the control oil pressure is generated only when controlling the cylinder pressure of the cylinder, and the control oil pressure can be reduced. Therefore, the sound vibration in the circuit can be suppressed to a small value, and the high pressure is always maintained. It is possible to improve the durability as compared with the conventional one that has been generated.

As described above, the running engine mounted on a vehicle has a great reduction in the load other than its intended purpose, and has the advantage that the total amount of exhaust gas can be suppressed.

[Brief description of the drawings]

FIG. 1 is a diagram showing in principle an active suspension device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing one embodiment of a control unit in FIG.

FIG. 3 is a sectional view showing one embodiment of a hydraulic cylinder in FIG. 2;

FIG. 4 is a sectional view showing one embodiment of the control valve in FIG. 2;

FIG. 5 is a sectional view showing an embodiment of the directional control valve in FIG. 2;

[Explanation of symbols]

 Reference Signs List 1 hydraulic cylinder 1e spring 2 hydraulic source 3 control valve 4 tank 5 supply path 5a check valve 6 discharge path 6a damping valve 6b accumulator 7 direction switching valve A axle suspension arm B body

Claims (1)

(57) [Claims] A vehicle is provided with a spring for supporting a vehicle load when the vehicle is empty. The spring is disposed on each of the four wheels of the vehicle. The upper end is connected to the vehicle body and the lower end is connected to the axle side. An active control for active control formed to individually generate the extension side or compression side cylinder pressure when supplied through a control valve that operates based on the road surface condition of the vehicle.
A double-acting hydraulic cylinder is provided , and the hydraulic pressure from each hydraulic source is supplied to each hydraulic cylinder via each supply path and each control valve, and the hydraulic pressure from each hydraulic cylinder is applied to the control valve and each hydraulic cylinder. And a check valve for preventing backflow in the supply path is provided in the supply path, and a discharge valve is provided via a damping valve in the discharge path. Accumulator is disposed, and a directional control valve is disposed in the discharge path, and the discharge path and the supply path or the discharge path and the tank can be selectively communicated by the operation of the directional control valve. An active suspension device, characterized in that: