JPH09142118A - Suspension control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve vehicle performance by a method wherein a relation between the tire of a vehicle and a road is constantly properly held by the active suspension of the vehicle. SOLUTION: From lateral acceleration Go or actual lateral acceleration G calculated from a car speed V and a steering angle θ, a lateral movement amount (w) of the center of gravity of a vehicle is estimated. To offset a roll occurring to a car body in correspondence to a lateral movement amount (w) of the center of gravity thereof, a control current Io fed to a control valve for an active suspension is read from a map 30. Meanwhile, to offset a total R of a camber angular change Ky read from from a map 31 in correspondence to a tire lateral force F calculated from actual lateral acceleration G and a camber angular change Kh read from a map 32 in correspondence to a steering angle θ, a control current IR fed to a control valve for an active suspension is read from a map 33. A control current I being a total thereof is outputted to an oil pressure control valve and the active suspension is controlled so that a ground camber angle is always adjusted to zero.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for controlling the attitude of a vehicle body by an active suspension.

[0002]

2. Description of the Related Art In order to reduce the vehicle body roll when the vehicle is turning, a so-called active suspension is used to adjust the height of the vehicle body in the front-rear and left-right directions by the fluid pressures supplied to the actuators of the left-right front-rear wheel suspension. As exemplified in Japanese Patent Application Laid-Open No. 125656, a technique for adding a control amount corresponding to a lateral acceleration acting on a vehicle body to a vehicle body at the time of turning of the vehicle has been conventionally known, and a roll control response generated at the time of vehicle steering. There is also known a technology in which the above-mentioned control amount is determined by the lateral acceleration calculated from the steering angle and the vehicle speed in consideration of the delay in the steering property. No consideration has been given to properly maintaining the relationship and sufficiently exhibiting the performance of the tire.

[0003]

SUMMARY OF THE INVENTION The present invention is intended to improve the performance of a vehicle by always maintaining an appropriate relationship between the tire of the vehicle and the road surface by an active suspension in the vehicle.

[0004]

Therefore, a suspension control device according to the present invention as set forth in claim 1 is a first means for detecting a traveling speed of a vehicle, a second means for detecting a steering angle of the vehicle, Third means for detecting the actual lateral acceleration of the vehicle, fourth means for calculating the lateral acceleration acting on the vehicle based on the vehicle speed detected by the first means and the steering angle detected by the second means, Fifth means for estimating the lateral displacement of the center of gravity of the vehicle from the actual lateral acceleration detected by the third means or the lateral acceleration calculated by the fourth means, and the lateral displacement of the center of gravity estimated by the fifth means. A first control means for determining a suspension control amount for canceling the roll of the vehicle from the amount; a sixth means for estimating a camber angle change of the vehicle from the actual lateral acceleration detected by the third means; A second control means for determining a suspension control amount for canceling the camber angle change estimated by the sixth means; and a final suspension control amount output based on the suspension control amounts from the both control means. It has three control means and controls so that the ground camber angle of the vehicle becomes substantially zero.

That is, the sixth means estimates the change in camber angle from the actual lateral acceleration detected by the third means, and the second control means determines the suspension control amount for canceling the change in the camber angle. The first control means determines a suspension control amount for canceling the roll of the vehicle from the lateral displacement amount of the center of gravity of the vehicle estimated by the fifth means, and the third control means determines the final suspension control amount based on both suspension control amounts. Is output, the camber angle to the ground of the vehicle is controlled to almost zero, so even if a lateral force actually acts on the tire, the change in the camber angle peculiar to the vehicle corresponding to the lateral force can be reliably ensured. By suppressing it, the ground camber angle of the vehicle is maintained at almost zero,
The relationship between the tire and the road surface can always be made appropriate.

According to a second aspect of the present invention, the suspension control device according to the present invention detects the traveling speed of the vehicle.
Means, second means for detecting the steering angle of the vehicle, third means for detecting the actual lateral acceleration of the vehicle, vehicle speed detected by the first means, and steering angle detected by the second means. Fourth means for calculating a lateral acceleration acting on the vehicle, fifth means for estimating a lateral movement amount of the center of gravity of the vehicle from the actual lateral acceleration detected by the third means or the lateral acceleration calculated by the fourth means. Means, a first control means for determining a suspension control amount for canceling the roll of the vehicle from the lateral displacement of the center of gravity estimated by the fifth means, and a camber angle of the vehicle from the steering angle detected by the second means. Sixth means for estimating a change, second control means for determining a suspension control amount for canceling the camber angle change estimated by the sixth means, and
It has a third control means for outputting the final suspension control amount based on the respective suspension control amounts from the both control means, and controls so that the ground camber angle of the vehicle becomes substantially zero.

That is, the camber angle change is estimated by the sixth means from the steering angle detected by the second means, and the second control means determines the suspension control amount for canceling this camber angle change. The first control means determines the suspension control amount for canceling the roll of the vehicle from the lateral movement amount of the center of gravity of the vehicle estimated by the five means,
Since the third control means outputs the final suspension control amount on the basis of both suspension control amounts, the ground camber angle of the vehicle is controlled to be substantially zero, so that the vehicle-specific steering angle corresponding to the vehicle steering angle is set. By reliably suppressing the camber angle change, the ground camber angle of the vehicle can be maintained at substantially zero, and the relationship between the tire and the road surface can always be made appropriate.

Further, the suspension control device according to the present invention as set forth in claim 3 comprises: a first means for detecting the traveling speed of the vehicle; a second means for detecting the steering angle of the vehicle; and an actual lateral acceleration of the vehicle. A fourth means for calculating a lateral acceleration acting on the vehicle by the third means for detecting, the vehicle speed detected by the first means, and the steering angle detected by the second means.
Means, the fifth means for estimating the lateral movement amount of the center of gravity of the vehicle from the actual lateral acceleration detected by the third means or the lateral acceleration calculated by the fourth means, and the above-mentioned means estimated by the fifth means. First control means for determining a suspension control amount for canceling the roll of the vehicle from a lateral movement amount of the center of gravity, sixth means for estimating a camber angle change of the vehicle from the actual lateral acceleration detected by the third means, and the sixth means. Seventh means for estimating the camber angle change of the vehicle from the steering angle detected by the two means, the sixth means and the seventh means
Second control means for determining a suspension control amount for canceling the camber angle change of the vehicle, which is respectively estimated by the means, and a final suspension control amount is output based on the suspension control amounts from the both control means. It has a third control means for controlling the vehicle so that the ground camber angle of the vehicle becomes substantially zero.

That is, the camber angle change is estimated by the seventh means from the steering angle detected by the second means, and the camber angle change is estimated by the sixth means from the actual lateral acceleration detected by the third means. The second control means determines the suspension control amount for canceling the change in the camber angle, and the first control means determines the suspension control amount for canceling the roll of the vehicle from the lateral movement amount of the center of gravity of the vehicle estimated by the fifth means when the vehicle turns. Is determined and the third control means outputs the final suspension control amount based on both suspension control amounts, so that the ground camber angle of the vehicle is controlled to be substantially zero. By reliably suppressing the change in camber angle peculiar to the corresponding vehicle, the ground camber angle of the vehicle is maintained at almost zero,
The relationship between the tire and the road surface can always be made appropriate.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention shown in the drawings will be described below. In FIG. 1, the hydraulic oil in a reservoir tank 1 mounted on a vehicle is sucked up by an oil pump 2 through an oil passage 3 and discharged to the oil passage 4 as pressure oil. 4F and rear wheel side oil passage 4R
The oil passages 4F, 4R further branch to the oil passages 4FL, 4FR, 4RL and 4RR for the left and right wheels, respectively, and to the suspension units 5FL, 5FR, 5RL and 5RR provided on the front, rear, left and right wheels, respectively. It is connected.

Each suspension unit 5FL, 5F
Since the R, 5RL, and 5RR have the same structure, the left front wheel suspension unit 5F is typically used.
Explaining L, a suspension spring 6 and a single-acting hydraulic actuator 7 are provided between the vehicle body and the wheels, and an oil passage 8 communicating with the hydraulic chamber of the hydraulic actuator 7 is connected via a control valve 9 which is a proportional solenoid valve. Is connected to the oil passage 4FL and the return oil passage 10.

The pilot oil pressure in the pilot oil pressure chamber for controlling the opening / closing of the control valve 9 is adjusted by the amount of pressure oil flowing from the pilot oil passage 11 branched from the oil passage 4FL to the return oil passage 10 via the oil passage 12. As a result of the pressure oil amount being controlled according to the control current from the controller 14, the opening of the control valve 9 is adjusted by the control current from the controller 14, and the hydraulic pressure in the hydraulic chamber of the hydraulic actuator 7 is controlled by the controller 14. It is controlled so as to be proportional to the current value.

An accumulator 15 filled with gas is connected to the oil passage 8 through a throttle 16. The accumulator 15 is configured to perform a gas spring action and a vibration damping action.

On the other hand, a relief valve 18 is provided in a relief oil passage 17 which connects the oil passage 4 and the return oil passage 10,
When the discharge hydraulic pressure of the oil pump 2 exceeds a predetermined value, the relief valve 18 is opened and the working oil is returned from the oil passage 4 to the reservoir tank 1.

The controller 14 includes a vehicle speed sensor 20 for detecting the vehicle speed V, a steering angle sensor 21 for detecting the steering angle θ of the steering wheel of the vehicle, and an actual lateral acceleration actually acting on the vehicle body in the lateral direction. The respective detection signals are sent from the lateral acceleration sensor 22 which detects G, and the controller 14 individually controls each control valve 9 based on these detection signals as will be described later, and the suspension units 5FL and 5FR for the respective wheels. 5RL and 5R
By controlling the stroke and spring constant of R independently,
It is possible to perform vehicle height adjustment and body attitude control.

Next, the control operation of the controller 14 will be described. When the vehicle is traveling, that is, the vehicle speed sensor 20
When the vehicle speed V> 3 km / h is detected, the controller 14 receiving the detection signal starts the control operation shown in the control block diagram of FIG. 2, and the steering angular speed dθ / dt> 1.
In the case of 5 ° / sec, the lateral acceleration Go acting on the vehicle body is calculated from the vehicle speed V and the steering angle θ, and the lateral movement amount w of the center of gravity of the vehicle body is estimated from the lateral acceleration Go based on the vehicle specifications. By estimating the lateral movement amount w of the center of gravity from the lateral acceleration Go,
There is no time delay in estimating the lateral movement amount w of the center of gravity at the beginning of steering or during sudden steering.

When the steering angular velocity dθ / dt ≦ 15 ° / sec, that is, when the steering angular velocity dθ / dt is small and the actual lateral acceleration G is detected with little time delay, or
When the actual lateral acceleration G acts on the running vehicle body due to side wind, inclination of the road surface, ruts on the road surface, etc. regardless of whether steering is performed, the center of gravity of the vehicle body is calculated from the actual lateral acceleration G based on the vehicle specifications. The lateral movement amount w is estimated.

Further, the suspension units 5FL, 5FR, 5RL are used to cancel the roll generated on the vehicle body in accordance with the lateral movement amount w of the center of gravity of the vehicle body estimated as described above.
A control current Io to the control valve 9 for controlling the vehicle body attitude control by controlling 5 and 5RR respectively is read from the value of the center-of-gravity lateral movement amount w in the map 30.

On the other hand, the lateral force F acting on the tire is calculated from the actual lateral acceleration G detected by the lateral acceleration sensor 22, and the camber angle change Ky predicted to be caused by the lateral force F is obtained by actual measurement. The camber angle change Kh predicted from the steering angle θ detected by the steering angle sensor 21 is read from the value of the lateral force F based on the map 31 and the steering angle θ based on the map 32 obtained by actual measurement. Read from the value of.

Next, the camber angle change Ky and the camber angle change Kh are added, and the suspension unit 5FL,
By the control of 5FR, 5RL and 5RR, the above added value R
The control current IR to the control valve 9 for making the camber angle change of 0 is read from the value of the addition value R in the map 33, and the final control current I which is the sum of the control current Io and the control current IR, that is, A vehicle roll control amount signal is output from the controller 14 to the control valve 9.

Therefore, each control valve 9 is individually controlled by the control current I, and the suspension units 5FL, 5FR, 5RL and 5RR for each wheel are independently controlled, so that the ground camber angle is always zero. Since the suspension can be controlled, the relationship between the tires and the road surface can be maintained properly regardless of the driving conditions, and the tires can be improved in turning limit performance, braking performance, steering feel, etc. By making full use of the performance possessed, it is possible to surely improve the performance of the vehicle.

Further, the control is performed so that the ground camber angle is set to zero rather than the change in the roll attitude of the vehicle body, so that the uneven wear of the tire can be easily reduced. When the vehicle is traveling at high speed, a relatively large actual lateral acceleration G occurs even at a small steering angle θ. However, since the steering angle θ is small, the negative camber effect due to the steering angle θ is small. Since the roll of is large and the change in camber angle becomes relatively large, canceling this change in camber angle and setting the ground camber angle to zero results in a gentle reverse roll posture of the vehicle, and Since the negative camber effect due to the steering angle θ is great at low speed and large steering angle, the ground camber angle should be zero even if the roll control amount is relatively small. It can be, there is an advantage that handling characteristics with a sense of security can be obtained.

[0023]

In the suspension control device according to the present invention, the vehicle is controlled so that the ground camber angle becomes substantially zero, and therefore even if a lateral force actually acts on the tire, the lateral force can be dealt with. By reliably suppressing the camber angle change peculiar to the vehicle, the ground camber angle of the vehicle can be maintained at almost zero, and the relationship between the tire and the road surface can always be made proper regardless of the running condition. It is possible to sufficiently exhibit the performance possessed by the tire, such as improvement in turning limit performance of the vehicle, improvement in braking performance, and improvement in steering feeling.

[Brief description of the drawings]

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

FIG. 2 is a control block diagram of the embodiment.

[Explanation of reference symbols] 2 Oil pump 7 Hydraulic actuator 9 Control valve 14 Controller 20 Vehicle speed sensor 21 Steering angle sensor 22 Lateral acceleration sensor 30, 31, 32, 33 Map

Claims (3)

[Claims] 1. A first means for detecting a traveling speed of a vehicle, a second means for detecting a steering angle of the vehicle, a third means for detecting an actual lateral acceleration of the vehicle, and a vehicle speed detected by the first means. And fourth means for calculating a lateral acceleration acting on the vehicle based on the steering angle detected by the second means, the actual lateral acceleration detected by the third means, or the lateral acceleration calculated by the fourth means. Fifth means for estimating the lateral displacement of the vehicle from the acceleration, first control means for determining the suspension control amount for canceling the roll of the vehicle from the lateral displacement of the vehicle estimated by the fifth means, and the third means. A sixth means for estimating a camber angle change of the vehicle from the actual lateral acceleration detected by the means; and a suspension control amount for canceling the camber angle change estimated by the sixth means. It has a second control means for determining and a third control means for outputting a final suspension control amount based on the suspension control amounts from both the control means, and the ground camber angle of the vehicle becomes substantially zero. Suspension control device to control as. 2. A first means for detecting a traveling speed of a vehicle, a second means for detecting a steering angle of the vehicle, a third means for detecting an actual lateral acceleration of the vehicle, and a vehicle speed detected by the first means. And fourth means for calculating a lateral acceleration acting on the vehicle based on the steering angle detected by the second means, the actual lateral acceleration detected by the third means, or the lateral acceleration calculated by the fourth means. Fifth means for estimating the lateral displacement of the vehicle from the acceleration, first control means for determining the suspension control amount for canceling the roll of the vehicle from the lateral displacement of the vehicle estimated by the fifth means, and the second means. Sixth means for estimating a camber angle change of the vehicle from the steering angle detected by the means, and a suspension control amount for canceling the camber angle change estimated by the sixth means And second control means for outputting the final suspension control amount based on the suspension control amounts from the both control means, so that the ground camber angle of the vehicle becomes substantially zero. Suspension control device to control. 3. A first means for detecting a traveling speed of a vehicle, a second means for detecting a steering angle of the vehicle, a third means for detecting an actual lateral acceleration of the vehicle, and a vehicle speed detected by the first means. And fourth means for calculating a lateral acceleration acting on the vehicle based on the steering angle detected by the second means, the actual lateral acceleration detected by the third means, or the lateral acceleration calculated by the fourth means. Fifth means for estimating the lateral displacement of the vehicle from the acceleration, first control means for determining the suspension control amount for canceling the roll of the vehicle from the lateral displacement of the vehicle estimated by the fifth means, and the third means. A sixth means for estimating a change in the camber angle of the vehicle from the actual lateral acceleration detected by the means, and a seventh means for estimating a change in the camber angle of the vehicle from the steering angle detected by the second means. The second control means for determining the suspension control amount for canceling the change in the camber angle of the vehicle estimated by the sixth means and the seventh means, and the suspension control amounts from the both control means. A suspension control device which has a third control means for outputting a final suspension control amount based on the above, and controls so that the ground camber angle of the vehicle becomes substantially zero.