JPH035220A - Suspension control device - Google Patents

Abstract

PURPOSE:To improve smooth ride and running stability by detecting the acceleration in the vertical direction on a car body, measuring the times of lasting the detected acceleration in the range of a specified time, and setting damping force at the time when the acceleration has reached the specified value. CONSTITUTION:The acceleration in the vertical direction on a car body 1 is detected by a means 2. The damping force of the shock-absorbers installed between respective wheels 3a and 3b and the car body 1 is also changed according to the command designated from the exterior by a means 4. In addition, car speed and door opening and closing are detected by means 6 and 6 respectively. The resonance on a spring is assumed detecting the lasting time of keeping the specified value of acceleration or higher, and the time of lasting is counted, and a command to change damping force based on the counted value is also output from a means 7. At this time, a command to keep the damping force slightly higher until the fact that the car stops and passengers riding or off is assumed, is output from the means 7.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a suspension control device that suppresses resonance due to sprung vibration of an automobile suspension.

[Conventional technology]

Generally, in a vibration model of a car, as shown in the equivalent model in Fig. 5, the mass of the car body (spring mass) is supported by the spring 1 of the suspension means and the damper C1, and the unsprung mass of the wheels etc. Ugly 2 is spring (tire) k! It is expressed as a two-degree-of-freedom system vibration supported by .

In such a vibration model, the vibration of the sprung member due to road surface stimulation has two resonance points as shown in Fig. 6, and the resonance point when the frequency is approximately 1.5 to 2H2 is the vibration of the sprung member due to road surface stimulation. The resonance point when the frequency is approximately 10 to 13 tlz is the unsprung resonance point due to the resonance of the unsprung member.

In order to improve riding comfort by reducing the vibration amplitude of the sprung member at such a resonance point, as can be seen from Fig. 6,
It is known that the damping force of the suspension means (the damping coefficient of the damper C) can be increased.

However, if the damping force of the suspension means is increased, a so-called "rugged" ride will be felt at areas other than the resonance point, which will actually worsen the riding comfort.

Therefore, by making the damping force of the suspension means variable and increasing the damping force from time to time when the resonant frequency region is on the sprung or unsprung side, vehicle body vibration can be effectively suppressed over the entire frequency range. However, there have been proposals for improving ride comfort (for example, Japanese Patent Laid-Open No. 59-227515). [Problems to be Solved by the Invention] In general, the damping of the main resonance of the spring is determined by the damping coefficient ratio (ζ-c /
2N■+), and the closer the damping coefficient ratio is to 1, the more the spring main resonance is suppressed, but it is usually set to 0.2 to 0.3 in consideration of riding comfort other than the resonance frequency.

Here, as the sprung mass increases due to an increase in the number of passengers and luggage, the damping coefficient ratio ζ becomes relatively small, and the damping of the spring main resonance becomes weaker, resulting in continued vibration and poor riding comfort.

Even if this spring main resonance is detected and the damping force is temporarily increased to increase the damping coefficient ratio to suppress the spring two-way resonance, if the damping force returns to its original state, the spring main resonance is likely to occur.

This invention was made to solve the above problems, and when the main spring resonance becomes more likely to occur due to an increase in the mass of the sprung mass, the vehicle stops and passengers and luggage are loaded and unloaded. It is an object of the present invention to provide a suspension control system capable of maintaining a high damping force until the end of the vehicle, suppressing spring main resonance, and improving riding comfort.

[Means to solve the problem]

The suspension control device according to the second invention, upon determining acceleration at a predetermined level or higher in both the vertical directions of the vehicle body, measures the number of times the acceleration is sustained within a predetermined time range, and attenuates when the number of times reaches a predetermined value. A control means for outputting a command to increase the force is provided.

[For production]

The control means 31 in the present invention measures the number of times that the acceleration of the vehicle body in both the vertical directions exceeds a predetermined level within a predetermined time range when the acceleration exceeds a predetermined level relative to a reference value, When this number of times exceeds a predetermined value, it is determined that the weight of the vehicle has increased and the damping coefficient ratio has become smaller, making it easier for spring L to resonate. Hold it high until it is
Suppresses spring main resonance.

〔Example〕

Hereinafter, embodiments of the suspension system jB Vi W of the present invention will be described based on the drawings. FIG. 1 is a block diagram showing the basic configuration of one embodiment, and the present invention is composed of the members described below.

That is, an acceleration detecting means 2 that detects the acceleration of the vehicle body 1 in both vertical directions, and a damping force that changes the damping force of the Shijisoku absorber disposed between the wheels 3a, 3b and the vehicle body 1 according to an external command. A changing means 4, a vehicle speed detecting means 5, a door opening/closing loading means 6 for detecting the opening/closing of the door, the magnitude of the acceleration, and the duration of the acceleration greater than a predetermined value, and the spring. Estimate the resonance frequency 1~,
The number of times of this duration is counted, and a command to change the damping force to a desired value is output to the damping force changing means 4 based on this count value. The control means outputs a command to the damping force changing means 4 to maintain a high damping force until the vehicle stops and it is estimated that passengers or cargo are loaded or unloaded.

FIG. 2 is a perspective view showing the arrangement of components mounted on a vehicle in an embodiment in which the present invention is applied to damping force switching, and FIG. 3 is a block diagram showing the configuration.

In FIGS. 2 and 3, reference numeral 11 indicates a steering sensor for detecting the operation status of the steering wheel, and reference numeral 5 indicates the vehicle speed detecting means, which will hereinafter be referred to as a vehicle speed sensor in this embodiment. 13 is an accelerator opening sensor for detecting acceleration/deceleration operations of the vehicle body 1, 14 is a brake switch, and 6 is a door opening/closing means, which will be hereinafter referred to as door switch 6 in this embodiment.

Further, the acceleration detecting means 2 detects the acceleration of the vehicle body 1 in both the vertical direction, and in this embodiment, it will be referred to as the vertical acceleration sensor 2 hereinafter.

As the vertical acceleration sensor 2, for example, an acceleration big amplifier or a differential transformer type acceleration sensor made of a piezoelectric material, or a semiconductor strain gauge type vertical acceleration sensor for automobiles is used.

In this embodiment, the vertical acceleration sensor 2 is installed at the center of gravity of the vehicle body 1, but it may be installed at the tip, at the front and rear, or at each suspension of each wheel.

Further, this vertical acceleration sensor 2 linearly outputs acceleration in both vertical directions as an analog voltage, centered on the output level at zero acceleration.

Note that 15 is a select switch, and 16 is an indicator, which includes the steering sensor 11, vehicle speed sensor 2, accelerator opening sensor 13, brake switch 14, vertical acceleration sensor 2, door switch 6, and select switch 15.
The output is manually inputted to the control means 7.

The output of the control means 7 controls the damping force of the damping force changing means 4, and also drives the indicator 16 to control the vehicle speed, opening/closing of the brake switch 13, etc.
Opening/closing of door switch 6, information on select switch 15,
Steering sensor 11 information, accelerator opening sensor 1
Information such as 3 is displayed.

Next, the operation will be explained. The output of the vertical acceleration sensor 2 is A/D (analog/digital) converted and input to a control means 7 constituted by a microcomputer, and the signal level change and vibration period of the vertical acceleration sensor 2 are calculated respectively.

Next, the processing procedure of the control means 7 will be explained according to the flowchart of FIG.

First, click "Start" and read the signal of the vertical acceleration sensor 2 in step S1, and in step s2 detect the magnitude of acceleration above a predetermined level in both the vertical direction with the specified value (±OG (acceleration)) of this signal as the boundary. Determine each.

In step S3, the duration of acceleration above a predetermined level is determined. If it is determined in step S4 based on the determination results in steps S2 and S3 that the duration of acceleration above a predetermined level is within a predetermined range, that is, that sprung mass resonance has occurred, the process proceeds to step S5; Increments the counter value by one.

Further, in step S4, if the duration of the acceleration equal to or higher than the predetermined level is not within the predetermined range, step S6
Proceed to.

In step S6, the value of the counter is determined, and if the value of the counter is greater than a predetermined value, that is, if the number of times of sprung resonance is greater than or equal to the predetermined number, the process proceeds to step S7, where the damping force is set higher.

If the number of sprung resonances is not greater than or equal to the predetermined number of times in step S6, the process advances to step S8.

In this step S8, it is determined whether there is an increase or decrease in the number of passengers or luggage in the vehicle.

That is, if the detection output of the vehicle speed sensor 5 is zero, the vehicle is stopped, and the door switch 6 detects that the door is open, it is determined that there has been an increase or decrease in the number of passengers or luggage.
Proceed to step S9.

In step S9, the counter is reset, and if the damping force is maintained at a high level, the damping force is returned to soft (rsOFTJ).

If rNOJ is determined in step S8, that is, there is no increase or decrease in the number of passengers or luggage, the process proceeds to the next step without changing the current state.

〔Effect of the invention〕

As described above, according to the present invention, when the number of times that the acceleration of the vehicle body in both the vertical directions equal to or higher than a predetermined level is sustained within a predetermined time range exceeds a predetermined value, the control device causes the damping force changing means to perform damping. Since the power was configured to be optimal,
As the number of passengers and luggage increases, the sprung mass of the vehicle increases, and the damping coefficient ratio becomes relatively small, making it easier for sprung resonance to occur. Switch to a higher setting to suppress sprung vibration and improve riding comfort.

In addition, by switching the damping force to a higher level, the higher damping force is maintained until passengers and luggage are loaded and unloaded, thereby constantly reducing the main vibration of the spring during driving due to the increase in the sprung mass, resulting in a comfortable ride. By increasing the damping force and increasing the damping force appropriately, it is possible to provide a suspension control device that prevents deterioration of running stability due to an increase in sprung mass.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the basic configuration of a suspension control device B according to an embodiment of the present invention, and FIG. 2 is a block diagram showing each embodiment in which the suspension control device of the present invention is applied to switching damping force. 3 is a block diagram showing the configuration of the embodiment shown in FIG. 2, and FIG. 4 is a flowchart of the operation of the control means in the embodiment shown in FIGS. 2 and 3. FIG. 5 is an equivalent schematic diagram showing a vibration model of an automobile, and FIG. 6 is a characteristic diagram showing resonance characteristics of a sprung member. DESCRIPTION OF SYMBOLS 1... Vehicle body, 2... Acceleration means, 4... Damping force changing means, 5... Duplex detection means, 6... Door opening/closing detection means, 7... Control means. In addition, it is shown. In the figure, the same No. 7γ is the same,

Claims (1)

[Claims] acceleration detection means for detecting acceleration in the vertical direction of the vehicle body;
A vehicle speed detection means for detecting vehicle speed, a door opening/closing detection means for detecting opening/closing of a door, and a plurality of suspensions provided between a wheel of a vehicle and the vehicle body and supporting the vehicle body for each corresponding wheel. The damping force changing means for varying the damping force of the suspension and the acceleration detecting means determine whether the magnitude of the acceleration is equal to or higher than a predetermined level in both the vertical direction with respect to the predetermined value of the output of the acceleration detecting means. and control means for controlling the damping force changing means so that the damping force of the suspension reaches an optimum value when the number of times the acceleration is sustained within a time range reaches a predetermined value.