JPH0481314A - Active suspension device for vehicle - Google Patents

Abstract

PURPOSE:To set the control pressure of oil pressure support means at an optimum value, and maintain a position of a vehicle constant by computing a weight of a car body on the basis of the oil pressure of each oil pressure support means against the car body, and correcting a position control gain of the car body on the basis of this real weight of the car body. CONSTITUTION:In suspension units 12 as oil pressure support means respectively provided in right and left front wheels and right and left rear wheels, a suspension spring 13 and a hydraulic actuator 14 are interposed between a car body and a wheel 8. A control valve 17 and a switching valve 22 of the suspension unit 12 are controlled by a controller 30 forming the oil pressure control means on the basis of each detecting signal from a lateral G sensor 31, a pressure sensor 35 and a front and rear G sensor 36 for detecting the acceleration in front and rear of the car body 7. In this case, the controller 30 computes a weight of the car body with the oil pressure inside of each hydraulic actuator 14, while correcting a position control gain of the car body on the basis of this weight of the car body.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention provides an active suspension for a vehicle that reduces roll or pitching of the vehicle body when turning or braking, and maintains a constant posture of the vehicle body. Regarding equipment.

(Prior Art) This type of active suspension device has a hydraulic actuator consisting of a hydraulic cylinder installed between the vehicle body and each wheel, and supports the vehicle body via these hydraulic actuators, that is, with hydraulic pressure. That's what I do. Therefore, if the vehicle body is supported hydraulically in this way, for example,
When the vehicle turns, the roll control pressure of the hydraulic actuator is calculated according to the lateral acceleration acting on the vehicle body and the roll control gain, and the hydraulic pressure of each hydraulic actuator is controlled based on this roll control pressure, thereby controlling the roll of the vehicle body. can be reduced or prevented.

Specifically, when the vehicle turns, control pressure is applied to the hydraulic pressure of the hydraulic actuator on the outer wheel of the turn to increase the oil pressure, while the oil pressure of the hydraulic actuator of the inner wheel of the turn is reduced by the amount equal to the control amount. This makes it possible to reduce or prevent the roll of the vehicle body and maintain a constant posture of the vehicle body.

(Problem to be Solved by the Invention) By the way, the roll control gain described above can be calculated from the vehicle weight, the height of the center of gravity, and the effective pressure receiving area of the tread and hydraulic actuator. Although each of the areas is a fixed value based on the vehicle specifications, especially regarding the vehicle weight,
It will fluctuate greatly depending on the increase or decrease in the number of passengers.

For this reason, conventionally, when calculating the roll control gain, the roll control gain is calculated assuming that the vehicle weight is a constant reference value.Therefore, the roll control gain is calculated regardless of the actual vehicle weight. , is always a constant value.

If the roll control gain is constant in this way, even if the vehicle weight increases or decreases, the roll control pressure of the hydraulic actuator will be calculated only from the magnitude of the vehicle's lateral acceleration, so the vehicle weight will be the standard. If the weight has increased from the standard value, the control pressure will be insufficient, causing the vehicle to roll; on the other hand, if the vehicle weight has decreased from the reference value, the control pressure will be excessive. This will result in

This invention was made based on the above-mentioned circumstances, and
The purpose is to appropriately calculate the control pressure for each hydraulic actuator regardless of changes in vehicle weight.
An object of the present invention is to provide an active suspension device for a vehicle that can optimally control the attitude of a vehicle body.

(Means for Solving the Problems) This invention provides hydraulic support means that are interposed between the vehicle body and each wheel to support the vehicle body, acceleration detection means that detects acceleration of the vehicle body, and changes in the posture of the vehicle body. In order to regulate the hydraulic pressure, the control pressure calculation means calculates the control pressure of the hydraulic support means based on the acceleration and the attitude control gain, and the hydraulic control means controls the supply and discharge of hydraulic pressure to each hydraulic support means based on the control pressure. In the active suspension device for a vehicle, the present invention includes pressure detection means for detecting the oil pressure in the control pressure calculation means or each hydraulic support means, and a vehicle weight for calculating the vehicle weight from the oil pressure in each hydraulic support means. The vehicle is configured to include a calculation means and a correction means for correcting the attitude control gain based on the vehicle weight.

(Function) According to the above-mentioned active suspension device, since the pressure detection means for detecting the hydraulic pressure of each hydraulic support means, that is, the support hydraulic pressure of the vehicle body, is provided, the hydraulic pressure of each hydraulic support means and the hydraulic pressure of each hydraulic support means are detected. The actual weight of the vehicle can be calculated from the effective pressure receiving area and the like. If the actual vehicle weight is calculated in this way, the attitude control gain can be corrected based on this actual vehicle weight. Therefore, from this corrected attitude control gain and the acceleration of the vehicle body, it is possible to correct the attitude control gain. By appropriately calculating the control pressure and controlling the hydraulic pressure of each hydraulic support means based on this control pressure, the attitude of the vehicle body can be optimally controlled.

(Example) FIG. 1 shows the configuration of a hydraulic active suspension system for a vehicle. This figure shows a suspension unit I2 as a hydraulic support means provided for each wheel, that is, front left and right wheels and rear left and right wheels, and a suspension spring 13 of this suspension unit 12 and a single-acting hydraulic cylinder. A hydraulic actuator 14 consisting of
are interposed between the vehicle body 7 and the wheels 8. Furthermore, the first
In the figure, a suspension unit combined with one wheel is representatively illustrated.

The control valve 17 of the suspension unit 12 is inserted between an oil passage 16 communicating with the hydraulic chamber 15 of the hydraulic actuator 14, and a supply oil passage 14 and a discharge oil passage 6, which will be described later. One end of a branch passage 16a is connected to the middle of the oil passage 16, and an accumulator 2o is connected to the other end of the branch passage 16a. Gas is sealed in the accumulator 2o, and due to the compressibility of the gas, a so-called gas spring action is exerted. A first throttle 19 is disposed in the middle of the branch path 16a, and this first throttle 19
regulates the amount of hydraulic oil flowing between the accumulator 2o and the hydraulic chamber 15 of the hydraulic actuator 14, thereby achieving a desired vibration damping effect.

A first throttle 1 is provided between the oil passage 16 and the accumulator 20.
A bypass path 16b that bypasses 9 is connected,
A second throttle 21 and a switching valve 22 are arranged in this bypass passage 16b.

The second aperture 21 has a larger orifice diameter than the first aperture 19. The switching valve 22 is in a closed state (the state shown in the figure) when the switching valve 22 is not energized, and when the switching valve 22 is switched to the open state, the hydraulic oil is transferred to the switching valve 2 in the open state.
2 and the second throttle 21 can flow between the accumulator 20 and the hydraulic chamber 15, thereby weakening the vibration damping effect. That is, by opening and closing the switching valve 22, the spring rigidity of the suspension unit 12 changes in two stages.

The other end of the supply oil passage 4 mentioned above is connected to the discharge side of the oil pump 1, and the suction side of the oil pump 1 communicates with the inside of the reserve tank 3 via the oil passage 2. Therefore, when the oil pump 1 is driven, the reserve tank 3
The hydraulic oil stored therein is discharged to the supply oil path 4 side. In the supply oil path 4, an oil filter 9, a check valve IO, and an accumulator 11 for maintaining line pressure are arranged in order from the oil pump 1 side. The check valve IO only allows the flow of hydraulic oil from the oil pump 1 side toward the suspension unit 12 side, and this check valve 10 allows high-pressure hydraulic oil to be stored in the accumulator 11.

The control valve 17 is of a type that changes its valve opening degree in proportion to the supplied current value, and depending on this valve opening degree, the control valve 17 changes the valve opening degree between the supply oil passage 4 side and the discharge oil passage 6 side. It is possible to control the supply and discharge of the amount of oil, that is, the supply and discharge of oil pressure to and from the hydraulic actuator 14. And control valve 17
The structure is such that the larger the current value supplied to the hydraulic actuator 14, the greater the hydraulic pressure within the hydraulic actuator 14, that is, the supporting force generated by the hydraulic actuator 14. The hydraulic oil discharged from the control valve 17 to the discharge oil path 6 side is returned to the reservoir tank 3 described above.

The control valve 17 and the switching valve 22 are electrically connected to the output side of a controller 30 constituting a hydraulic control means, and their operation is controlled by a drive signal from the controller 30. Therefore, controller 3
Various sensors are connected to the input side of 0, respectively.
These sensors include a lateral G sensor 31 that is attached to the vehicle body 7 and detects the lateral acceleration Gy acting on the vehicle body 7, a vehicle height sensor 32 that is provided for each wheel and detects the stroke amount of the wheel, and a steering wheel of the vehicle. A steering wheel angle sensor 33 that detects the steering angle θH (not shown), and a vehicle speed V of the vehicle.
There is a vehicle speed sensor 34 etc. that detects the vehicle speed.

Furthermore, the controller 30 includes each hydraulic actuator 1.
4 and the vehicle body 7.
A sensor signal from a longitudinal G sensor 36 that detects the longitudinal acceleration of the vehicle is also input. Pressure sensor 3
In this embodiment, in the oil passage 16 connecting between the hydraulic actuator 14 and the control valve 17, 5 detects the pressure led from the part of the oil passage 16 on the hydraulic actuator 14 side. ing.

Therefore, the aforementioned control valve 17 and switching valve 22 are
The operation is controlled by the controller 30 based on the detection signal of each sensor.

During normal driving, the switching valve 22 is closed, and slight vibrations input to the vehicle body from the road surface are suppressed because the hydraulic chamber 15 of the hydraulic actuator 14 communicates with the accumulator 20 via the first throttle 19. , absorbed and attenuated.

Next, the operation of the suspension unit H2 controlled by the controller 30, that is, the roll control which is one of the posture controls of the vehicle body 7, will be explained with reference to the block diagram shown in FIG.

First, the oil pressure p obtained from each pressure sensor 35 is supplied to the calculation condition determination section 40 . Here, this calculation condition determination unit 4
0, the oil pressure p++pt+p'll obtained from the four pressure sensors 35 that form a pair with each hydraulic actuator 14.
I) 4 will be supplied, and these oil pressure pz
p2.1)3. p4 indicates the oil pressure in the hydraulic actuator 14 on the front, rear, left, and right sides of the vehicle body. In addition, the calculation condition determination unit 40 also contains the lateral acceleration Gy obtained by the lateral G sensor 31 and the longitudinal acceleration Gf obtained by the longitudinal G sensor 36. The calculation condition determining unit 40 determines whether the calculation conditions are satisfied based on the magnitude of the lateral acceleration Gy and the longitudinal acceleration Gf. In the case of this embodiment, when each of the absolute value IGyl of the lateral acceleration Gy and the absolute value IGfl of the longitudinal acceleration Gf is 0.1 G or less, the calculation condition determination unit 40 performs calculation for the next calculation unit 41. A command signal S will be output.

The calculation unit 41 adds the oil pressures in each hydraulic actuator 14 obtained by the pressure sensor 35 based on the following formula, and calculates the vehicle body 7.
The total support hydraulic pressure P that supports the is calculated.

P=Σp.

Here, i represents the subscript of the oil pressure p.

The total support hydraulic pressure P calculated by the calculating part 41 is then multiplied by the actuator section coefficient A in the calculating part 42, thereby calculating the vehicle weight ~1.

Here, the actuator section modulus A is set in consideration of the total effective pressure receiving area of each hydraulic actuator 14 and the total supporting force of each suspension spring 13.

When the vehicle weight M is calculated based on the oil pressure from each pressure sensor 35 as described above, since the calculation command signal S is output from the calculation condition determination section 40 described above, in other words, the lateral acceleration Since the absolute value of GV (1 Gyl) and the absolute value IGf of longitudinal acceleration (Gf) are each less than 0.1 G, in such a situation, the vehicle is either stopped running or Even if the vehicle is running, it is in a stable constant speed running state. Therefore, when the vehicle is in such a state, if the vehicle weight M is calculated based on the oil pressure in each hydraulic actuator 14 obtained by the pressure sensor 35, the calculated vehicle weight M is
This will be an accurate value.

The vehicle weight M obtained by the calculation unit 42 is then processed by the calculation unit 43 as follows:
It is used to calculate the roll control gain KR.

The roll control gain KR is the hydraulic actuator 1 for canceling the load movement on the left and right sides of the vehicle body caused by the lateral acceleration Gy of the vehicle body 7 when the vehicle turns, that is, the moment force.
This is for finding the control pressure ΔP of No. 4, and can be calculated from the following equation.

KR=MxF(/(dxa)) Here, M indicates the vehicle weight as mentioned above, and as is clear from FIG. 3, H is the height of the center of gravity of the vehicle body 7,
d indicates the tread, and a indicates the effective pressure receiving area of the hydraulic actuator 14.

The calculated roll control gain KR is then calculated by the calculation unit 44.
The above-mentioned lateral acceleration Gy is also supplied to this calculation section 44. Therefore,
The calculation unit 44 calculates the roll control gain KR and the lateral acceleration Gy.
Therefore, as shown in the following equation, the hydraulic actuator 1
The roll control pressure ΔPR of 4 is calculated.

ΔPR=KRxGy When the roll control pressure ΔPR is calculated in this way, the controller 30 supplies a valve control signal corresponding to the roll control pressure ΔPR to the control valve 17 of the hydraulic actuator 14, thereby controlling this control valve. 17 is controlled, whereby the hydraulic pressure within the hydraulic actuator I4 is controlled based on the roll control pressure ΔPH.

Specifically, when the vehicle turns, the hydraulic pressure in the hydraulic actuator 14 on the outer wheel side of the turn is increased based on the roll control pressure ΔPR, while the hydraulic pressure in the hydraulic actuator 14 on the inner wheel side of the turn is increased based on the roll control pressure ΔPR.
The hydraulic pressure within the cylinder will be controlled based on the negative roll control pressure, i.e. -ΔPR. If the oil pressure in each hydraulic actuator 14 is controlled in this way, when the vehicle turns,
The load movement on the left and right sides of the car body 7 caused by the lateral acceleration of the car body 7, that is, the moment force, can be canceled out by the roll control pressure ΔPH, effectively reducing or preventing the roll of the car body 7, and keeping the attitude of the car body 7 constant. It becomes possible to maintain the

In the embodiment described above, when calculating the roll control pressure ΔPR, the roll control gain KR is corrected based on the actually calculated vehicle weight M, so the calculated roll control pressure ΔPR is based on the vehicle weight M. This is the optimum value for implementing roll control of the vehicle body 7 when turning. Therefore, even if the number of occupants of the vehicle changes and the vehicle weight M fluctuates, the roll control pressure ΔPR will not become insufficient or excessive when the vehicle turns, and the roll control pressure of the vehicle body 7 will not become insufficient or excessive. can be effectively reduced or prevented.

Furthermore, the vehicle weight M is determined when the lateral acceleration Gy and longitudinal acceleration Gf acting on the vehicle body 7 are small, that is, when the vehicle is at a standstill or is running at a stable constant speed.
Since it is calculated based on the sensor signal from the pressure sensor 35, the calculated vehicle weight M is an accurate value.

This invention is not limited to the one embodiment described above, and various modifications are possible. For example, in one embodiment:
Although the lateral acceleration GY acting on the vehicle body 7 is detected by the lateral G sensor 31, the present invention is not limited to this, and the lateral acceleration GY may be calculated based on the steering wheel angle θH and the vehicle speed V. That is, the lateral acceleration Gy can be calculated from the following equation.

Gy=θHXV2/C(1+Ksxy2)XIXO] Here, Ks is a stability factor, and ρ is a handle gear ratio.

If the lateral acceleration GY is calculated from the above equation, the problem of response delay that the lateral G sensor 31 has can be solved.

Further, in one embodiment, the present invention is applied to one of the posture control of the vehicle body 7.
Although the present invention has been applied to roll control, it goes without saying that the present invention can also be applied to pitching control of the vehicle body 7 in addition to roll control.

In the case of pitching control, each of the pitch control gain Kp corresponding to the roll control gain KR and the pitch control pressure ΔPp in the hydraulic actuator 14 can be calculated from the following equation.

Kp = MxH/ (LXa) Δpp = Kp XGf Here, L indicates the wheel base of the vehicle as shown in FIG.

As is clear from the above two equations, pitch control pressure ΔPp
In calculating the vehicle weight M, the pressure sensor 35
If the pitch control gain Kp is calculated based on the sensor signal from the vehicle and calculated from the calculated vehicle weight M, then the pitch control gain Kp can be calculated, regardless of the fluctuation of the vehicle weight M, when the vehicle is braking or accelerating when starting. The dive or swat of the vehicle body 7 can be optimally regulated by the pitch control pressure Δpp. Specifically, even when the vehicle is braking, the hydraulic pressure in the hydraulic actuator 14 at the front of the vehicle is increased based on the pitch control pressure Δpp, whereas the hydraulic actuator 14 at the rear of the vehicle increases its hydraulic pressure. is reduced based on the pitch control pressure. Note that when the vehicle accelerates, such as when starting, the oil pressure in each hydraulic actuator 14 is controlled based on the pitch control pressure ΔPp in a direction opposite to that during braking.

(Effects of the Invention) As explained above, according to the active 4° suspension system for a vehicle of the present invention, the hydraulic pressure of each hydraulic support means is detected by the pressure detection means. The weight of the vehicle can be calculated based on the pressure applied, that is, the oil pressure of each hydraulic support means. Therefore, if the vehicle weight is actually calculated in this way, even if the vehicle weight varies due to the number of occupants, it is possible to correct the vehicle attitude control gain based on the actual vehicle weight. The control pressure of the hydraulic support means calculated from the attitude control gain and the acceleration of the vehicle body becomes the optimal value for implementing attitude control such as roll control or pitching control of the vehicle body, and as a result, the attitude of the vehicle body is maintained constant. It has excellent effects such as:

[Brief explanation of the drawing]

FIGS. 1 to 3 show one embodiment of the present invention.
The figure is a schematic configuration diagram of the active suspension system, Figure 2 is a block diagram for explaining the calculation of vehicle weight carried out by the controller, and Figure 3 is a roll control that cancels the roll of the vehicle body when turning. A diagram to explain pressure,
FIG. 4 is a diagram for explaining the pitch control pressure that cancels the dive of the vehicle body during braking. 7... Vehicle body, 8... Wheel, 14... Hydraulic actuator, 17... Control valve, 30... Controller, 31... Lateral G sensor, 33... Handle angle sensor, 34... ...Vehicle speed sensor, 35...Pressure sensor, 3
6... Front and rear G sensor. Applicant Mitsubishi Motors Corporation Agent Patent Attorney Kan Nagato Figure 3 Figure 4

Claims (1)

[Claims] Hydraulic support means interposed between the vehicle body and each wheel to support the vehicle body; An active suspension device for a vehicle, comprising: a control pressure calculation means for calculating a control pressure of a hydraulic support means based on an attitude control gain; and a hydraulic control means for controlling supply and discharge of hydraulic pressure to each hydraulic support means based on the control pressure. The control pressure calculation means includes a pressure detection means for detecting the oil pressure of each hydraulic support means, a vehicle weight calculation means for calculating the vehicle weight from the oil pressure of each hydraulic support means, and an attitude control gain based on the vehicle weight. An active suspension device for a vehicle, comprising a correction means for correcting.