JPH02296517A - Suspension controller for vehicle - Google Patents

Abstract

PURPOSE:To preform excellent control with yet fewer sensors by detecting displacement or the like in the horizontal direction of a vehicle with a fork vibration type angular velocity sensor or the like making a specified shaft in the vehicle of its detection shaft, and thereby controlling a suspension. CONSTITUTION:Horizontal displacement of a vehicle is detected by a fork structural vibration type angular velocity sensor 11, and vertical displacement of the vehicle is detected by a supersonic wave road sensor 12, while vehicle speed is detected by a car speed sensor 13. Then, on the basis of each detection signal, a specified arithmetic process is performed by an electronic controller 14, while damping force of a shock absorber is regulated by an actuator 15. At this time, the angular velocity sensor 11 is attached so as to make a shaft in relation of mutually 45 degrees with an X-axis or a traveling direction of the vehicle and a Y-axis or car width direction of its detection shaft. With this constitution, angular velocity in the roll direction in an X-axis and another nagular velocity in the pitch direction in the Y-axis both are detected by one angular velocity sensor 11.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a vehicle suspension control device that controls the suspension of a vehicle to vary the state of the vehicle suspension in accordance with the driving conditions of the vehicle to improve ride comfort and handling. It is something.

BACKGROUND OF THE INVENTION In recent years, advances in semiconductors have led to the development of LSIs and microcomputers with complex arithmetic processing functions, and these have been used to realize control equipment with detailed control functions. The reliability of these control devices has also improved, and technology has been realized that guarantees normal operation even in extremely harsh environments such as those installed in vehicles. Against this background, it is being utilized particularly for vehicle control that requires fine-grained control. Particularly recently, suspension control devices have been actively developed for the purpose of improving ride comfort and handling of vehicles. Conventionally, this type of device uses information from multiple sensors installed on the vehicle to detect disturbances such as rolling and pitching of the vehicle that occur during vehicle operation, and calculates the suspension's spring constant and The damping force and stroke have been varied to ensure ride comfort and handling.

An embodiment of a conventional suspension control device will be described with reference to FIG. The vehicle is equipped with many sensors, and the detection information from these sensors is manually input to the electronic controller 1, which is a calculation processing unit, and switches the actuator built into the shock absorber 2, which is a component of the suspension, to adjust the damping force. It is designed to perform i'lil control by making it variable. For example, in order to prevent the tail from sinking during acceleration, there is an anti-dive function that uses input from the throttle position sensor 3 and vehicle speed sensor 4 to prevent the tail from sinking during braking or engine braking.
In order to prevent the water from sinking, an anti-dive function is provided which is controlled by input from the brake switch 5 and vehicle speed sensor 4.
In order to prevent horizontal vibrations caused by steering operations, an anti-roll function is controlled by inputs from the steering sensor 6 and vehicle speed sensor 4, and to prevent vertical vibrations caused by the condition of the road surface, the road surface sensor 7 and vehicle speed sensor 4 are used. Anti-bounce function, controlled by the input of
It has the following functions.

In addition to the vehicle speed sensor, throttle position sensor, brake switch, steering sensor, and road surface sensor mentioned above, other suspension control systems also include acceleration sensors, clutch switches, parking brake switches, door switches, and many other devices. There are also examples using sensors.

Problems to be Solved by the Invention In general, when emphasis is placed on ride comfort, the suspension is set to be softer, and when emphasis is placed on handling stability, the suspension is set to be stiffer. In conventional implementations, when steering stability is more important than ride comfort, there are many causes of disturbances such as rolling and pitching, such as changes in vehicle speed, changes in steering, and changes in road surface conditions. It is a system that changes the state of the suspension in anticipation of disturbances such as rolling and pitching of the vehicle that will occur next time, and detecting the phenomena that cause the disturbance. This may require a large number of sensors, the calculation process may become complicated because the control is based on predictions, and in the worst case, there is a possibility that incorrect control may be performed that does not match the actual displacement of the vehicle. There was also.

In contrast, a system has been proposed in which the displacement of the vehicle is directly detected using a small number of sensors to control the state of the suspension, as described in, for example, Japanese Patent Application Laid-Open No. 63-68413.

An object of the present invention is to enable the state of a suspension to be controlled with a small number of sensors.

Means for Solving the Problems In order to solve the above problems, the present invention provides a tuning fork structure vibration type angular velocity sensor, a sensor for detecting vertical displacement of a vehicle, a vehicle speed sensor, and a system based on output signals of these sensors. The spring constant, damping force, and throat stroke of the suspension are changed based on the results of the calculation process using an electronic controller that performs calculation processing and an actuator installed in the suspension of the vehicle.

If the structure is configured as above, disturbances such as rolling, pitching, etc. can be directly and accurately detected using a tuning fork structure vibration type angular velocity sensor and a sensor that detects vertical displacement of the vehicle. The state of the vehicle during high-speed driving can be detected by a vehicle speed sensor, and the state of the suspension can be varied in accordance with these sensor output signals, making it possible to improve the ride comfort and handling of the vehicle.

Embodiment Hereinafter, an embodiment of a suspension control device for a vehicle according to the present invention will be described based on the drawings.

First, a tuning fork structure vibration type angular velocity sensor for detecting changes in a vehicle will be explained using FIGS. 5 to 7.

The angular velocity sensor has a structure as shown in FIG. 5, and is mainly composed of a driving element made of four piezoelectric bimorphs, and first and second sensing elements.
A first vibration unit 109 in which 03 is orthogonally joined at a joint 105, a monitor element 102, and a second detection element 104.
The second vibration unit 11 is orthogonally joined at the joining part 106.
0 are connected by a connecting plate 107, and this connecting plate 107 is supported at one point by a support rod 108 to form a tuning fork structure. When a sinusoidal voltage signal is applied to the drive element 101, the first vibration unit 109 starts to vibrate due to the inverse piezoelectric effect, and the second vibration unit 110 also starts to vibrate due to the tuning fork vibration. Therefore, the charge generated on the surface of the monitor element 102 due to the piezoelectric effect is proportional to the sinusoidal voltage signal applied to the drive element 101. The charge generated in the monitor element 102 is detected, and the drive element 102 is arranged so that the charge has a constant width.
By controlling the sinusoidal voltage signal applied to the tuning fork, stable tuning fork vibration can be obtained.

The mechanism by which this sensor generates an output proportional to the angular velocity will be explained using FIGS. 6 and 7. Figure 6 shows the angular velocity sensor shown in Figure 5 viewed from above, and shows the speed υ
When rotation at an angular velocity ω is applied to the sensing element 103 which is vibrating at , a "Coriolis force" is generated in the sensing element 103.

This "Coriolis force" is perpendicular to the speed υ and has a magnitude of 2 mυ
It is ω. Since the detection element 103 is vibrating like a tuning fork,
If the sensing element 103 is vibrating at a speed υ at a certain point, the sensing element 104 is vibrating at a speed -υ, and the "Coriolis force" is -2 mυω.

Therefore, the sensing elements 103 and 104 are connected to each other as shown in FIG.
The Coriolis force acts (deforms in the direction, and a charge is generated on the element surface due to the piezoelectric effect. Here, υ is the movement caused by the vibration of the tuning fork, and the vibration of the tuning fork is υ=a-sinωot a: the amplitude of tuning fork vibration ω0 :
If it is the period of sound or vibration, the "Coriolis force" is Fc=a 1 sin ωot, which is proportional to the angular velocity ω and the tuning fork amplitude a, and becomes a force that deforms the sensing elements 103 and 104 in the plane direction. Therefore, the surface charge Q of the sensing elements 103, 104 is Qαa″ω・SinωOt, and if the tuning fork amplitude a is controlled constant, QOCω6sin ωot, the surface charge Q generated on the sensing elements 103, 104.
is obtained as an output proportional to the angular velocity ω, and this signal is expressed as ω
If synchronous detection is performed at Ot, a DC signal proportional to the angular velocity ω can be obtained. Note that even if a translational motion other than angular velocity is applied to this sensor, charges of the same polarity are generated on the surfaces of the two sensing elements 103 and 104, so when converted to a DC signal, they cancel each other out and the output is output. It looks like there isn't.

FIG. 1 shows an embodiment of the vehicle suspension control device according to the present invention, which is composed of a sensor group including the tuning fork structure vibration type angular velocity sensor 11, the ultrasonic road surface sensor 12, and the vehicle speed sensor 13 described above in FIG. The suspension control device includes an electronic controller 14 that performs arithmetic processing based on the output signals of these sensors, and an actuator 15 that varies the damping force of a shock absorber that is a component of the suspension.

FIG. 2 is a diagram in which the above-mentioned sensor, control unit, and actuator are mounted on a vehicle. The axis with the same relationship as the detection axis should be installed. With this configuration, one angular velocity sensor can detect the angular velocity in the roll direction occurring on the X-axis and the angular velocity in the pitch direction occurring on the Y-axis. Further, the ultrasonic road surface sensor 12 is attached to the lower part of the chassis of the vehicle so as to be able to detect the displacement of the vehicle in the vehicle height direction, and detects the vertical position of the vehicle. Further, the vehicle speed sensor 13 outputs a digital signal according to the running of the vehicle. These sensor groups installed on the vehicle detect the vehicle's attitude, and the electronic controller 14 performs calculation processing to minimize the displacement of the vehicle due to external disturbances. The actuator 15 that changes the damping force of the shock absorber, which is a component of the controller, is controlled. The specific operation will be explained based on FIGS. 3 and 4. FIGS. 3 and 4 show control during boarding and traveling and control for disturbance phenomena to be controlled, based on signals from various sensors. First of all, the running conditions of a normal vehicle are divided into three categories: when the vehicle is stopped or running at low speed (~5 km/h), when people are getting on and off the vehicle, when the vehicle is stopped, and when loading and unloading luggage. The suspension condition is set to be stiffer (stopping control function) due to changes in the load on the entire vehicle, as well as disturbances immediately after starting or just before stopping (stopping control function).When the vehicle is running at medium speed (approx.
km/h), and ride comfort is emphasized, so unless there is a particular disturbance, the suspension condition is set to be soft (medium speed driving tense function). If the vehicle is traveling at high speed (approximately 8
0 to km/h), and the suspension is set to be stiffer to emphasize maneuverability (high-speed driving control function).

Here, the suspension is unconditionally set to be stiff when the vehicle is stopped, traveling at low speeds, or traveling at high speeds, so that the displacement of the vehicle in response to external disturbances is not large.

Next, when the vehicle is running at medium speed (approximately 5 to 80 km/h
), the suspension is set to be soft to improve ride comfort, but as soon as a disturbance occurs, the suspension is set to be stiffer and controlled to minimize vehicle displacement. For example, as shown in FIG. 4(b), when cornering, the vehicle is displaced in the roll direction, so an angular velocity is generated in the X-axis direction, and a signal detected by the angular velocity sensor 11 is sent to the electronic controller 14. As an anti-roll function, the electronic controller 14 sends a command to the actuator 15 to stiffen the suspension. Further, as shown in FIG. 4(a), when the vehicle accelerates rapidly, an angular velocity is generated in the Y-axis direction because the vehicle is displaced in the pitch direction, and a signal detected by the angular velocity sensor 11 is sent to the electronic controller 14. Then, as an anti-dive function, the electronic controller 14 sends a command to the actuator 15 to stiffen the suspension. Similarly, as shown in FIG. 4(C), angular velocity is generated in the pitch direction during control such as braking, and a command is sent to stiffen the suspension as an anti-dive function. Furthermore, as shown in Figure 4(d), if there are protrusions or dents on the road surface, or if the vehicle pitches vertically due to road conditions, the vehicle will be displaced in the Z-axis direction, which is the vehicle height direction. occurs, a signal detected by the road surface sensor 12 is sent to the electronic controller 14,
As an anti-bounce function, the electronic controller 14 sends a command to the actuator 15 to stiffen the suspension. After these disturbances subside, the suspension returns to its softer state due to the normal medium-speed driving tense function.

In the above-mentioned embodiments, a road surface sensor that detects the condition of the road surface using ultrasonic waves is used as a sensor that detects the vertical displacement of the vehicle, but an acceleration sensor that detects acceleration may be configured. Also good. Further, in the embodiment, the shock absorber of the suspension is controlled by the actuator, but the spring constant and stroke of the suspension can also be controlled by the actuator.

As described in detail, the present invention uses a tuning fork structure vibration type angular velocity sensor, a sensor that detects the vertical displacement of both, and a vehicle speed sensor to directly detect displacement due to vehicle disturbance, and improves suspension performance. It is possible to provide a suspension performance control device that can control the spring constant, damping force, and stroke, and takes both riding comfort and handling stability into consideration.

In addition, a road surface sensor or acceleration sensor using ultrasonic waves is placed as a sensor to detect vertical displacement of the vehicle, and an angular velocity sensor detects axes that are at a 45 degree angle with respect to the vehicle's traveling direction and vehicle width direction. By arranging the sensor around the axis, it is possible to detect roll and pitch displacements and accurately capture displacements caused by vehicle disturbances.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the suspension control device according to the present invention, FIG. 2 is a schematic diagram showing how sensors are mounted on a vehicle, FIGS. FIG. 5 is a perspective view of the tuning fork structure vibration type angular velocity sensor in FIG. FIG. 11... Angular velocity sensor, 12... Road surface sensor, 13... Vehicle speed sensor, 14...
・Electronic controller, 15... Actuator, 101... Drive element, 102...
・Monitor element, 103...first detection element,
104...Second sensing element, 105°106.
...Joint part, 107...Connection plate, 109
...First vibration unit, 110...
Second vibration unit. Name of agent Patent attorney Shigetaka Awano Idiot 1 @ 1 Figure Figure 3 Figure 2 Ward 2 # Figure Figure Figure 6 Figure Figure

Claims (4)

[Claims] (1) An angular velocity sensor whose detection axes are axes that are parallel to the road surface on which the vehicle is running and are at a 45 degree relationship with respect to the X-axis in the direction of travel of the vehicle and the Y-axis in the width direction of the vehicle; A sensor that detects directional displacement, a vehicle speed sensor that detects vehicle speed, an arithmetic processing section that performs arithmetic processing based on these sensor output signals, and an actuator that is controlled based on the arithmetic processing and is provided on the suspension of the vehicle. A suspension control device for a vehicle, comprising: controlling the attitude of the vehicle by changing the spring constant, damping force, stroke, etc. of the suspension using the actuator. (2) The angular velocity sensor includes a first vibration unit formed by orthogonally joining a driving piezoelectric bimorph element and a first sensing bimorph element, and a monitoring piezoelectric bimorph element and a second sensing bimorph element. It consists of a second vibration unit which is orthogonally connected to each other and the first and second vibration units.
The angular velocity sensor has a tuning fork structure in which the free ends of the driving piezoelectric bimorph element and the monitoring piezoelectric bimorph element are connected to each other by a connecting plate so that the vibration units are parallel to each other along the detection axis. The vehicle suspension control device according to claim (1). (3) The vehicle suspension control device according to claim (1), wherein the sensor that detects the vertical displacement of the vehicle is a road surface sensor that detects the condition of the road surface using ultrasonic waves. (4) The vehicle suspension control device according to claim (1), wherein the sensor that detects vertical displacement of the vehicle is an acceleration sensor that detects acceleration of the vehicle.