JPS59227514A - Suspension of automobile - Google Patents

Abstract

PURPOSE:To reduce uncomfortableness resulting from rolling of a car body in a variable suspension by comparing the output of a steering angle sensor with the average steering angle up to the time of the output to derive the difference therebetween, comparing the difference to the reference determined according to car speed and controlling the steering characteristics according to the compared result. CONSTITUTION:A controller 15 receives a steering angle detecting signal 16a and a speed detecting signal 16b and calculates the difference between the signal 16 and the input steering angle calculated by averaging summed steering angle. Based on the input car speed, the controller determines the spring force changeover discriminating reference value Qx of each of springs 5 and 6 and the attenuating force changeover discriminating reference value Qy of each of dampers 3b and 4b. The absolute value of the difference between the steering angle and the average value is compared with the reference values Qx and Qy. If the absolute value is over Qx, the spring forces of the springs 5 and 6 are increased while if the value is over Qy, the attenuating forces of dampers 3b and 4b are increased. The uncomfortableness resulting from rolling of the car's body may be thus reduced.

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a suspension system for an automobile, and particularly to a suspension device that hardens suspension characteristics during cornering to reduce rolling of the vehicle body.

BACKGROUND ART Conventionally, attempts have been made to reduce the rolling of the vehicle body by stiffening the spring constant of the springs and the damping rate of the damper, that is, the suspension characteristics of the suspension joists, during cornering. For example, according to Japanese Utility Model Application Publication No. 56-147107, in a car equipped with shock absorbers on the front and rear wheels, roll speed is detected based on signals from a steering angle sensor and a vehicle speed sensor. A device has been disclosed in which the damping force of the shock absorber is increased when the above situation occurs. However, according to this invention, when the vehicle speed is high, there is a risk that the damping rate of the shock absorber will be increased even if the steering angle has a small amount of play in the steering wheel. Even during steady turning at a steering angle, that is, while the roll angle of the vehicle body is maintained substantially constant, the shock absorber remains unnecessarily stiff.

In other words, rolling of the vehicle body has a negative effect on ride comfort only during rolling movements when tilting sideways from a normal position and returning to a normal position from a tilted position, but only when the vehicle body is making steady turns. As long as the roll angle is maintained at a constant roll angle, there is no need to make the suspension characteristics particularly hard.

Therefore, it is conceivable to use the differential value of the steering angle to control the suspension characteristics, and make the suspension characteristics hard only when the differential value is above a certain value, that is, while the steering wheel is operated at a certain sharpness or above. . According to this, the suspension characteristics are returned to a soft state during steady turning, and a good ride comfort during steady turning can be obtained. However, even with this method, the problem of the suspension characteristics becoming too hard due to the play of the handle cannot be solved.

Purpose of the Invention The present invention provides a suspension with variable suspension characteristics.
Depending on the play of the steering wheel, the suspension characteristics will not be hard.
Another object of the present invention is to provide a suspension in which the suspension characteristics are made hard only when the vehicle body rolls from a normal posture to a tilted posture and when it rolls from a tilted posture to a normal posture, causing discomfort to the occupant. shall be.

The automobile suspension of the present invention includes a suspension device with variable suspension characteristics, a means for changing the suspension characteristics of the suspension device, a steering angle sensor for detecting a steering angle, and a control for controlling the operation of the adjusting device. and means;
The control means compares the output value of the steering angle sensor with the average value of the output value up to the relevant point in time, and the difference is small when the vehicle speed is large, and is set to a reference value that is large when the vehicle speed is small. The present invention is characterized in that it is configured to output an operating signal to the adjustment means to harden the suspension characteristics of the suspension device when the suspension exceeds the suspension characteristic.

In the automobile suspension of the present invention having the above configuration, the suspension characteristics are not hardened by a steering angle as small as the play of the steering wheel, and when turning, when the steering angle suddenly increases from zero, and When the steering angle is returned to zero, that is, when the vehicle body performs a rolling motion, the suspension characteristics are made hard and the rolling motion is suppressed.On the other hand, when the zero roll angle state continues, and the vehicle body is approximately constant. During a steady turn where the roll angle is maintained at a roll angle of In the present invention, the reference value for changing the cutting blade of the suspension characteristic is set to be small when the vehicle speed is high, and large when the vehicle speed is low. Therefore, regardless of the vehicle speed, the suspension characteristics can be set to bar P under the same roll conditions.

EXAMPLE Hereinafter, an automobile suspension according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a schematic perspective view showing a suspension system for an automobile according to an embodiment of the present invention, and FIG. 2 is a system diagram of its main parts.

A front wheel suspension 1 and a rear wheel suspension 2 are provided to accompany the front wheels and rear wheels, respectively.The suspensions 1 and 2 are each equipped with a spring sa
s 4a and oreodan/? 3 b.

4b, and further includes a shock absorber 3.4 consisting of
An air spring 5.6 constituted by a diaphragm made of a suitable elastic material is provided around the spring/f3b, 4i). The dampers 3b and 4b are variable dampers whose damping force can be adjusted, and therefore the orifice provided in the piston (not shown) has a variable diameter. In order to change the diameter of this orifice, a sylanger (not shown) driven by a solenoid 7.8 is provided in the piston condo 3044c, and this sylanger is rotated by the energized solenoid 7.8. The diameter of the orifice is reduced, and Dan/f3b
The damping force of %4b has been increased to make the suspension characteristics of suspension 1.2 harder. The air spring 5.6 is connected to the air chamber 11.1 controlled by the air pipe 9.10.
The state of communication between the air spring 5.6 and the air chamber 11.12 is controlled by the operation of the Tasolenoi P pulps 13 and 14 provided at the entrances of the chambers 11 and 12, respectively. In this example, communication is cut off when the solenoids of solenoid valves 13.14 are energized. When the communication between the air spring 5.6 and the air chamber 11.12 is cut off in this way, the effective volume of the air chamber of the air spring 5.6 decreases, so that the spring force of the air spring 5.6 decreases. Strong p
, the suspension characteristics of suspension 1.2 become harder.

The controller 15 excites the solenoid 7.8 for adjusting the damping force of the variable dampers 3b, 4b and the solenoid valve 13.14 for adjusting the spring force Wd of the air spring 5.6. A steering angle detector 168 is connected to the controller 15. The steering angle detector 168 detects the steering angle θ of the steering wheel H and outputs a steering angle signal S indicating the steering angle. Also connected to the controller 5 is a vehicle speed detector 16b that detects the vehicle speed of the automobile and outputs a vehicle speed signal Sv indicating this vehicle speed. The controller 5 receives a steering angle signal Sl, which is an analog signal output from the steering angle detector 16, as shown in FIG.
It has a D converter 17.

At the output end of this A/Q i converter 17, this A/D
The steering angle signal S, digitized by the transducer.

to the weighted average value of the steering angle shown by the following formula 111% (2) (hereinafter the first weighted average value, respectively)
An arithmetic circuit 18 is connected to calculate the second summer average value. Note that the weighted average value r is a value for spring control;

O no J? It is for control.

r-(k-1) return + θ', -0-8-, -111(
p-1) In-1+”1 θ.=□・・・・・・・・・(2) In the above formulas (1) and (2), 'm-1, θ.-1 is,
Each weighted average value K used in the previous control.

σ1 is the steering angle signal Sθ.
represents the current steering angle indicated by . Note that the weighted average value σm1%Io-1 used in the previous control is O stored in the storage circuit 19. The absolute values 1θl'ml and 1σ1-61 of the differences between the average values "m and /n" and the current steering angle /1 are calculated.

The arithmetic circuit 18 also receives a vehicle speed signal Sv from the vehicle speed detector 16b, and based on this vehicle speed signal Sv, a first reference value σ× for determining whether or not the spring force of the barb 5.6 should be changed. , and a second reference value σ for determining whether or not the damping force of the dampers 3b and 4b should be switched. These first and second reference values θ8, θ,
It is desirable that the setting is determined based on a semi-hyperbolic vehicle speed-reference value characteristic curve C as shown in FIG. That is, the first and second reference values l51x%
Iy is set to be small when the vehicle speed is high, and large when the vehicle speed is low.

Next, the absolute value lσI'ml calculated above is applied to the spring 5.
σ, which is the above setting value at which the spring force of 6 should be switched;
Determination of whether b is greater than or not, and absolute value lθI−frn
It is determined whether l is larger than θ, which is the set value for switching the damping force of the dampers 3b and 4b. When the above-mentioned determination of l'l G'>θx is YES, the arithmetic circuit 18 outputs a pulp actuation signal Ss to actuate the solenoid valves 13 and 14 via the output device 20. Then, increase the spring force of springs 5 and 6. Further, the arithmetic circuit 18 operates according to the above-mentioned 1/ll-/, 1. )P, if the judgment is YES, the output device 20f sends the solenoid activation signal S to the solenoid r7.8 to activate the solenoid 7.8.
By outputting o, the damping force of Danno, 3b, and 4b can be adjusted. However, the arithmetic circuit 18 receives the solenoid actuation signal S. When the valve actuation signal SS is outputted, the valve actuation signal SS is not outputted for a predetermined period of time (see Fig. 5) from the time of output. This is solenoid 7.
8 and solenoid valves 13 and 14 at the same time, this is to prevent power consumption from becoming large at one time.

The electric circuit 18 that performs each of the above functions of the arithmetic circuit 18 will be explained with reference to FIG.

The electric circuit 18 includes a spring control system including a first integrating circuit 188, a first differential amplifier 18b, and a first comparator 18c;
Second integrating circuit 18d1 Second differential amplifier 18e and second integrating circuit 18d1
It is equipped with a dan/thousand control system consisting of a comparator 18 and a reference value generating device 21 consisting of a frequency-voltage converter 19 and a function generator 20. The first and second integrating circuits 1
8a118d is the weighted number of shoes mentioned above! has a time constant corresponding to the current steering angle σ1 from the steering angle detector 16.
By inputting the steering angle signal Sσ indicating the above equations (1) and (2
), the weighted average value r% of the steering angle is calculated.
The first and second differential amplifiers 18b and 18e output weighted average value signals S''[11 and S,o2 indicating
is equipped with absolute value circuits 18b' and 188', and an integral circuit 1
8as 18d to weighted average value signal S,01',
02 and the steering angle signal S from the steering angle detector 16,
From these signals above +Il-rml i- and I'
Calculate iGl.

Function generator 201-j of the reference value generator 21: Generates a function as shown in FIG.
Upon receiving the voltage signal Sv indicating the vehicle speed from the voltage converter 19, a reference value x1θ, σset corresponding to the vehicle speed is determined.
Output. The comparators 18c and 18f are connected to the +t
It is determined whether i(-ttp + and +tii-o, 1) is larger than the set value θ8.19y, θset, and when it is larger, the valve actuation signal S and the solenoid valve -*So are outputted. Valve actuation signal SD is input, the predetermined time ΔT from the time of input, for example, 0.5
Open signal S after seconds. When the dart is received, the dart is opened, and only then the pulp actuation signal Ssf from the comparator 18C is passed through the solenoid valve 13.14, thereby causing the dunn/
The spring force of the spring 5.6 is switched with a delay in the switching operation of the damping force of f3E1%4b.

Next, the controller 5 configured as described above performs
The spring force of the above spring 5.6 and the above Dan” 3bs
Steering angle I, spring 5.6 when controlling the damping force of 4b
a first weighted average value C9 used to control the spring force of the valve actuation signal S5, to a second weighted average value used to control the damping force of Danno 43b, 4b;
The relationship between the solenoid actuation signal S, the roll angle change a%, and the roll angle change rate will be explained with reference to FIG.
If the first weighted average value changes as shown by the solid line, the first weighted average value changes as shown by the broken line in FIG. 6(A). For the first weighted average value width, it is desirable to set a large number of weighting k so that it changes gradually in this way, and to reduce the weight of the current steering angle θ.In the above case, the difference between θ and 4 is the above setting. A period larger than the value σset is a period marked with a slash.

During the above period, the controller 5 operates L1 as shown in FIG. 6 (8).
In addition, the above-mentioned valve actuation signal SS is output, the solenoid valves 13 and 14 are closed, and the spring force of the spring 5.6 is strengthened. As a result, the roll angle change amount is
As shown in Figure (C), it is controlled so that it does not exceed a predetermined value.

On the other hand, the second weighted average value 17rn changes as shown by the broken line in FIG. 6(D). The second weighted average value irn is thus relatively @1. It is desirable to set the number of times of weighting small so that the steering angle changes rapidly, and to set a large weight on the current steering angle θ. In the above case, the difference between I and to is the set value'
A period larger than set t is a period indicated by a slash in υ in Figure 6. During this period, the controller 15 outputs a solenoid activation signal S as shown in the sixth same color). output, reduce the diameter of the orifice of Dan"3bs4b, and increase the M force of Dan/#3b%4b. In other words, it is made to operate only during a predetermined period at the beginning of turning the steering handle H when the roll speed is high. In other words, the operation of the dampers 3b and 4b is stopped before the operation of the spring 5.6 is stopped.As a result, the steering wheel speed is changed as shown in FIG. 6(F). Dahan r le H
While the change is limited to only at the beginning of the turn, the damp/"3b%4b is softened in the middle of the car's turn, so the ride comfort is improved.

As described above, in this embodiment, the spring force of the spring and the damping force of the damper are comprehensively controlled when the automobile turns, thereby making the riding comfort even better. Furthermore, in this embodiment, the weighted average value of the steering angle is used as the reference value for controlling the spring force of the spring and the damping force of the damper, so the initial settings of the steering angle detector etc. can be made more precisely. Further, there is an advantage that a complicated differential circuit for detecting or calculating the rate of change in the steering angle is not required.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view showing an automobile suspension according to an embodiment of the present invention, FIG. 2 is a system diagram of the main parts of the suspension shown in FIG. 1, and FIG. 3 is a diagram similar to that shown in FIG. Figure 4 is a graph showing the characteristic curve showing the relationship between military speed and reference value; Figure 5 is the function of the arithmetic circuit shown in Figure 3. FIG. 6 is a time chart for explaining the function of the arithmetic circuit. 1.2...Suspension, 3b, 4b...Oleodan" %5%6... Electric spring, 7.8... Solenoid, 13.14... Solenoid valve, 15... Controller 16... Rudder angle detector. Patent applicant: Toyo Kogyo Co., Ltd. 6 Part 1, Part 2, 脩＄!r-shot〉 9 Ward summary

Claims (1)

[Claims] A suspension device with variable suspension characteristics, an adjustment device that changes the suspension characteristics of the suspension device, a steering angle sensor that detects a steering angle, and a control device that controls the operation of the adjustment device, the control device comprising: The output value of the steering angle sensor is compared with the average value of the output value up to the relevant point in time, and when the difference exceeds the base value, which is set small when the vehicle speed is high and large when the vehicle speed is low, A suspension system for an automobile, characterized in that the suspension system is configured to output an actuation signal for hardening the suspension characteristics of the suspension device to the adjustment means.