JPH06143957A - Suspension control device - Google Patents

Abstract

PURPOSE:To provide a suspension control device capable of preventing the damping force and spring constant of a suspension, or the torsional force of a stabilizer from being unnecessarily changed. CONSTITUTION:The suspension control device is composed of a switch 3 for selecting a target road clearance of a car body 1, a height sensor 4, means 5 to 7 for changing the damping force and spring constant of a suspension, or the torsional force of a stabilizer, a road clearance changing means 8, and a control device 9. The control device 9 transforms a relative displacement between the sprung- and unsprung masses of a vehicle detected by the height sensor 4 into a relative displacement to the target height, then performs Fourier transformation of the displacement to calculate power spectrum of vertical vibration of the car body, thus detects the frequency of vertical vibration of the car body, and properly controls the damping force, etc., of the suspension. Further, within a fixed time period from the time when the target road clearance is changed, switching of the damping force and spring constant of the suspension, and the torsional force of the stabilizer is not performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension controller for automatically adjusting a damping force of a suspension, a spring constant, a torsional force of a stabilizer and the like to optimum values according to vertical vibration of a vehicle body.

[0002]

2. Description of the Related Art Conventional suspension control devices for vehicles include those disclosed in, for example, Japanese Patent Application Laid-Open No. 3-227711 and Japanese Patent Application Laid-Open No. 61-18513. The former is to change the hard side value of the damping force commanded by the damping force control means in accordance with the spectrum sum calculation value obtained by Fourier transforming the vertical acceleration detection value of the vehicle. The latter is to control the damping force to an appropriate characteristic when it is determined that the vibration of the vehicle body is near the sprung resonance or the unsprung resonance above a predetermined level.

[0003]

By the way, after converting the relative displacement between the sprung and unsprung portions of the vehicle into the displacement with respect to the target vehicle height, Fourier transform is performed to calculate the power spectrum of the vertical vibration of the vehicle body. It is possible to detect the frequency of vertical vibration of the vehicle body using the power spectrum value and appropriately control the damping force of the suspension. in this case,
When the target vehicle height is switched with the vehicle height selection switch, etc., the amount of displacement with respect to the target vehicle height appears, so the power spectrum value is calculated even if the vehicle body is not actually vibrating.
There is a problem that the damping force of the suspension may be switched according to the power spectrum value.

Similarly, it is possible to detect the frequency of vertical vibration of the vehicle body by using the value of the power spectrum to appropriately control the spring constant of the suspension and the torsional force of the stabilizer. There is a problem that the spring constant and the twisting force may be switched even if the vehicle body is not actually vibrating when switching.

The present invention has been made to solve the above problems, and a suspension control device and a stabilizer control which can prevent unnecessary switching of the damping force and spring constant of the suspension or the twisting force of the stabilizer. The purpose is to provide a device.

[0006]

A suspension control device according to the present invention is provided between each wheel of a vehicle and a vehicle body, and includes a plurality of suspensions for supporting the vehicle body with respect to the corresponding wheels. A stabilizer arranged between wheels of a vehicle to prevent twisting of the vehicle body, a changing means for changing a damping force or a spring constant of the suspension or a twisting force of the stabilizer, and a vehicle height of the vehicle. Vehicle height changing means, relative displacement amount detecting means for detecting the relative displacement amount between the sprung and unsprung portions of the vehicle, target vehicle height selecting means for selecting the target vehicle height of the vehicle, and the relative displacement amount. Vehicle height control means for controlling the vehicle height changing means on the basis of the detection value of the detection means and the target vehicle height value selected by the target vehicle height selection means to set the vehicle height of the vehicle as a target value; Relative displacement amount calculating means for converting the detected value of the relative displacement amount detecting means into relative displacement amount with respect to the target vehicle height, and a power spectrum of vertical vibration of the vehicle body based on the relative displacement amount converted by this relative displacement amount calculating means. A power spectrum calculating means for calculating, a spectrum sum calculating means for calculating the sum of spectra near the sprung resonance frequency and the sum of spectra near the unsprung resonance frequency from the power spectrum calculated by the power spectrum calculating means, and Control means for switching at least one of the damping force or spring constant of the suspension or the twisting force of the stabilizer according to each spectrum sum calculated by the spectrum sum calculation means, and the target vehicle height selection means selects the target vehicle height. The suspension by the control means is maintained within a certain time from the time when the height is changed. Or of the damping force or spring constant is obtained so as not to perform switching control of the torsional force of the stabilizer.

[0007]

According to the present invention, the switching control of the damping force of the suspension or the spring constant or the torsional force of the stabilizer is not performed by the control means within a fixed time after the target vehicle height is changed by the target vehicle height selection means. It is possible to prevent unnecessary switching of the damping force or spring constant of the suspension or the torsional force of the stabilizer when the target vehicle height is switched.

[0008]

【Example】

Example 1. 1 is a block diagram showing an embodiment of a suspension control device according to the present invention. In this example, a select switch 3 as a target vehicle height selecting means for selecting a target vehicle height of the vehicle body 1, and a vehicle height as a relative displacement amount detecting means for detecting a relative displacement amount between the sprung and unsprung portions of the vehicle body 1. A sensor 4, damping force changing means 5 for changing the damping force of a suspension arranged between the vehicle body 1 and the wheel 2, spring constant changing means 6 for changing the spring constant of the suspension, and between the wheel 2 and the wheel 2. It comprises a twisting force changing means 7 for changing the twisting force of the arranged stabilizer, a vehicle height changing means 8 for controlling the vehicle body 1 to a set vehicle height, and a control device 9 for controlling the suspension and the stabilizer as a whole.

The control device 9 converts the detected value of the vehicle height sensor 4 into a relative displacement amount with respect to the target vehicle height and a relative displacement amount calculation means 9a, and the relative displacement amount converted by the relative displacement amount calculation means 9a is Fourier-transformed. Power spectrum calculation means 9b for converting and calculating a power spectrum of vertical vibration of the vehicle body;
A spectrum sum calculating means 9c for calculating the sum of spectra near the sprung resonance frequency and the sum of spectra near the unsprung resonance frequency from the power spectrum calculated by the power spectrum calculating means 9b, and the spectrum sum calculating means 9c. A determination unit 9d that determines the damping force of the suspension, the spring constant, and the torsional force of the stabilizer according to the calculated spectrum sums, and the damping force changing unit 5 and the spring constant that change based on the determination result of the damping force determination unit 9d. Control means 9e for controlling the means 6 and the twisting force changing means 7 to switch the damping force and spring constant of the suspension or the twisting force of the stabilizer, and the vehicle height controlling means for controlling the vehicle height changing means 8 so as to reach the target vehicle height. 9f.

In this example, the damping force changing means 5, the spring constant changing means 6, and the torsional force changing means 7 are used for a fixed time from the time when the target vehicle height is changed by the select switch 3 by the damping force of the suspension or the spring. Control so that the constant and the twisting force of the stabilizer are not switched.

FIG. 2 shows a specific embodiment of the suspension control device, and is a perspective view of a state in which the above-mentioned components are mounted on a vehicle. Further, FIG. 3 is a block diagram showing its configuration. 2 and 3, parts corresponding to those in FIG. 1 are designated by the same reference numerals. In the figure, 10 is a vehicle speed sensor as a vehicle speed detecting means, 11 is a steering angular velocity sensor for detecting an operation state of a steering wheel, 12 is a lateral G sensor for detecting lateral acceleration of the vehicle body, and 13 is an acceleration / deceleration operation of the vehicle body 1. Is an accelerator opening sensor, 14 is an indicator. In addition, 8a-8
Reference numeral f indicates a vehicle height changing means.

The outputs of the select switch 3, the vehicle height sensor 4, the vehicle speed sensor 10, the steering angular velocity sensor 11, the lateral G sensor 12, and the accelerator opening sensor 13 are input to the control device 9, which controls the damping force changing means. 5,
The vehicle height changing means 8 and the indicator 14 are controlled.
The vehicle height sensor 4 outputs an analog voltage value according to a relative displacement amount between the sprung portion and the unsprung portion of the vehicle body 1. This vehicle height sensor 4
A / D conversion of the analog voltage value output by (A /
The D converter is not shown), and is input to the control device 9 composed of a microcomputer.

Next, the operation procedure of the controller 9 will be described with reference to FIGS.
It will be described with reference to the flowchart of FIG.
FIG. 4 shows a process executed every predetermined sampling time ΔT (for example, 6 msec) to determine an appropriate damping force from the frequency and magnitude of the vehicle body vibration obtained from the target vehicle height and the relative displacement amount with respect to the target vehicle height. There is. Further, FIG. 5 also shows processing executed every predetermined sampling time ΔT to control the damping force of the suspension to the appropriate damping force obtained in FIG. 4 and to control the vehicle height to the target vehicle height.

In FIG. 4, the target vehicle height is set according to the state of the select switch 3 in step 101, and it is determined in step 102 whether the target vehicle height has been switched. If the target vehicle height has been switched, the damping force is determined in step 103. The determination prohibition time T1 is set to a predetermined value, and if not switched, the time T1 is decremented in step 104. Next, in step 105, the vehicle body 1 detected by the vehicle height sensor 4
And the relative displacement amount x1 of the wheel 2 is detected.

Next, in step 106, the relative displacement amount x2 of the vehicle body with respect to the target vehicle height set in step 101 is calculated. Then, in step 107, the relative displacement amount x2 with respect to the target vehicle height read every ΔT time is subjected to fast Fourier transform. By performing the process of step 107, the power spectrum data as shown in FIG. 7 is obtained from the data of the relative displacement amount as shown in FIG. Next, in step 108, power spectra are added in a width of ± 1 Hz centered on the sprung resonance frequency of the vehicle (1 Hz in this embodiment) from the power spectrum data obtained in step 107, and the value is set as P1. To do. Also in step 109, the power spectrum is added from the data of the power spectrum obtained in step 107 with a width of ± 1 Hz centered on the unsprung resonance frequency of the vehicle (10 Hz in this embodiment), and the value is set to P2. .

Next, at step 110, it is judged whether the time T1 or more has elapsed since the target vehicle height was switched, and if it has elapsed, the routine proceeds to step 111. In step 111, the optimum damping force for suppressing the vibration of the vehicle body is set based on the values of P1 and P2 calculated in steps 108 and 109 and the map of FIG. That is, when the power spectrum P1 near the sprung resonance frequency increases, the damping force is set to be solid (HARD), and when the power spectrum P2 near the unsprung resonance frequency is increased, the damping force is softened (SOFT). Set.

Next, referring to FIG. 5, steps 201 to 2
At 06, a command is issued to the damping force changing means 5 according to the damping force set at step 111 to switch to the target damping force.
Then, in step 206, the displacement amount x2 with respect to the target vehicle height
Is greater than or equal to a predetermined value, a command is issued to the vehicle height changing means 8 to start vehicle height adjustment (step 207), and when the displacement x2 with respect to the target vehicle height becomes smaller than a predetermined value, vehicle height adjustment is ended (step 208). .

Here, the processing shown in the flow charts of FIGS. 4 and 5 will be described with reference to FIG. Before the target vehicle height is switched (see time t0), the relative displacement x2 with respect to the target vehicle height is almost 0, so P1 and P2
Is not detected. When the target vehicle height is switched at time t1, the relative displacement amount x2 with respect to the target vehicle height is detected until time t3 when the actual vehicle height x1 is controlled to the target vehicle height. At this time, P1 and P2 are calculated by the value of the detected relative displacement amount x2, and even if the target damping force is normally in the SOFT region, if the map of FIG. 8 is followed, it will fall within the MEDIUM or HARD region. Become. Therefore, a damping force determination prohibition time T1 (t2-t1) is provided immediately after the target vehicle height is switched until the spectral values of P1 and P2 settle down to prevent unnecessary switching.

[0019]

According to the present invention, a plurality of suspensions are provided between each wheel of a vehicle and a vehicle body and support the vehicle body with respect to the corresponding wheels, and between the wheels of the vehicle. A stabilizer for preventing twisting of the vehicle body, a changing means for changing the damping force or spring constant of the suspension or the twisting force of the stabilizer, and a vehicle height changing means for changing the vehicle height of the vehicle, Relative displacement amount detection means for detecting the relative displacement amount between the sprung and unsprung portions of the vehicle, target vehicle height selection means for selecting the target vehicle height of the vehicle, detection value of the relative displacement amount detection means, and the above The vehicle height control means for controlling the vehicle height changing means based on the target vehicle height value selected by the target vehicle height selecting means to set the vehicle height of the vehicle as a target value, and the detection value of the relative displacement amount detecting means. Target car Relative displacement amount calculating means for converting into a relative displacement amount, power spectrum calculating means for calculating a power spectrum of vertical vibration of the vehicle body based on the relative displacement amount converted by the relative displacement amount calculating means, and this power spectrum calculating means The spectrum sum calculation means for calculating the sum of spectra near the sprung resonance frequency and the sum of spectra near the unsprung resonance frequency from the power spectrum calculated by the means, and the spectrum sum calculated by the spectrum sum calculation means. A control means for switching at least one of the damping force or spring constant of the suspension or the twisting force of the stabilizer in accordance with the above, and within a certain time from the time when the target vehicle height is changed by the target vehicle height selection means. The damping force or spring constant of the suspension by the control means or the stabilizer Since the switching control of the twisting force of the riser is not performed, it is possible to satisfactorily prevent the damping force of the suspension or the spring constant or the twisting force of the stabilizer from being unnecessarily switched when the target vehicle height is switched. There is.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a suspension control device according to the present invention.

FIG. 2 is a perspective view showing a positional relationship when members of a specific embodiment of the suspension control device according to the present invention are mounted on a vehicle.

FIG. 3 is a block diagram showing the configuration of the embodiment of FIG.

FIG. 4 is a flowchart showing the operation of the control device in the embodiment of FIG.

5 is a flowchart showing the operation of the control device in the embodiment of FIG.

FIG. 6 is a diagram showing a variation in the relative displacement amount of the vehicle body with respect to the target vehicle height when the target vehicle height is constant during traveling on a sloping road.

FIG. 7 is a diagram showing a power spectrum obtained by performing a fast Fourier transform on the relative displacement amount of FIG.

FIG. 8 is a power spectrum P1 in the sprung resonance frequency region.
It is a figure which shows the appropriate damping force map with respect to the power spectrum P2 of the unsprung resonance frequency region.

9 is a target vehicle height for explaining the embodiment of FIG. 2, a relative displacement amount x1 between the sprung and unsprung portions, a relative displacement amount x2 with respect to the target vehicle height, a power spectrum P1 in a sprung resonance frequency region, and a spring. 7 is a timing chart showing a power spectrum P2 and the like in the lower resonance frequency region.

[Explanation of symbols]

 1 Vehicle Body 2 Wheels 3 Select Switch 4 Vehicle Height Sensor 5 Damping Force Changing Means 6 Spring Constant Changing Means 7 Torsional Force Changing Means 8 Vehicle Height Changing Means 9 Control Device 10 Vehicle Speed Sensor 11 Suspending Angular Speed Sensor 12 Lateral G Sensor 13 Accelerator Opening Sensor 14 Indicator

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[Procedure amendment]

[Submission date] May 13, 1993

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

[Fig. 2]

Claims (1)

[Claims] 1. A vehicle body is provided between each wheel of a vehicle and a vehicle body,
A plurality of suspensions that support the vehicle body with respect to the corresponding wheels, a stabilizer that is disposed between the wheels of the vehicle and prevents the vehicle body from twisting, a damping force or a spring constant of the suspension, or Changing means for changing the twisting force of the stabilizer; vehicle height changing means for changing the vehicle height of the vehicle; relative displacement amount detecting means for detecting the relative displacement amount between the sprung and unsprung portions of the vehicle; Target vehicle height selecting means for selecting a target vehicle height of the vehicle, and controlling the vehicle height changing means based on the detection value of the relative displacement amount detecting means and the target vehicle height value selected by the target vehicle height selecting means. Vehicle height control means for setting the vehicle height of the vehicle as a target value, relative displacement amount calculation means for converting the detected value of the relative displacement amount detection means into relative displacement amount with respect to the target vehicle height, and the relative displacement amount The power spectrum calculation means for calculating the power spectrum of the vertical vibration of the vehicle body based on the relative displacement amount converted by the quantity calculation means, and the sum of the spectra near the sprung resonance frequency from the power spectrum calculated by this power spectrum calculation means. And a spectrum sum calculating means for calculating the sum of spectra in the vicinity of the unsprung resonance frequency, and a damping force of the suspension or a spring constant or a twisting force of the stabilizer according to each spectrum sum calculated by the spectrum sum calculating means. A control means for switching at least one of the above, and within a certain time from the time when the target vehicle height is changed by the target vehicle height selection means, the damping force or spring constant of the suspension or the twist of the stabilizer by the control means. Characterized by not performing force switching control Suspension control device.