JPH0443812B2 - - Google Patents

Description

[Detailed description of the invention] TECHNICAL FIELD The present invention relates to a suspension of a motor vehicle.

The suspension device of an automobile has the role of supporting the weight of the vehicle and cushioning road surface irregularities.
This has a significant impact not only on ride comfort, but also on pitching and rolling during driving, as well as stability and responsiveness when turning. Therefore, it is desirable to be able to variously change the dynamic characteristics of an automobile by appropriately changing the characteristics of the suspension of the front and rear wheels. For example, in Utility Model Application No. 56-147107, the roll speed (roll angle change rate) is detected using a steering sensor that detects changes in steering angle and a vehicle speed sensor, and control that increases the damping force of all-wheel shock absorbers is implemented. A device has been proposed that uses control to prevent the roll speed during turning from exceeding a predetermined value. According to this device, the roll speed is slowed down when turning, making it possible to improve both maneuverability and ride comfort, but controlling the shock absorber alone cannot reduce the roll angle itself, that is, the amount of change in the roll angle. This was not possible, and improvements in this respect were desired.

SUMMARY OF THE INVENTION An object of the present invention is to provide a suspension control device that can suppress not only the rate of change in roll angle but also the amount of change in roll angle when an automobile turns.

The present invention provides a suspension for an automobile that includes a variable damping force damper and a variable spring force spring for suspending automobile wheels on a vehicle body, and includes a damping force adjusting means for adjusting the damping force of the variable damper, and a damping force adjusting means for adjusting the damping force of the variable spring. A spring force adjusting means for adjusting a spring, a steering angle detecting means for detecting a steering angle of a steering wheel, and a steering angle signal outputted by the steering angle detecting means are inputted, and a roll angle change rate is indicated based on this steering angle signal. A steering angle signal processing means that calculates and outputs a roll angle change rate signal and a roll angle change amount signal indicating the roll angle change amount, and inputs the roll angle change rate signal and roll angle change amount signal, and calculates the roll angle change. When the rate of change in roll angle indicated by the rate signal is larger than a set value, a variable damper control signal that increases the damping force of the variable damper is output to the damping force adjustment means, while the roll angle indicated by the amount of change in roll angle signal is output to the damping force adjusting means. control means for outputting a variable spring control signal that increases the spring force of the variable spring to the spring force adjustment means when the amount of change is larger than a set value, and the steering angle signal processing means receives input from the steering angle detection means. The system generates a signal based on the difference between the reference steering angle and the actual steering angle obtained by averaging the steering angle signals obtained by going back a predetermined period of time, and in the averaging process, the roll angle change rate signal is It is characterized in that it is obtained by performing averaging processing in which the actual steering angle is weighted more heavily than the reference steering angle compared to the angular change amount signal.

In the automobile suspension of the present invention having the above structure, the spring force of the spring as well as the damper is variable, and when the amount of roll angle change exceeds a set value, the spring force adjustment means adjusts the spring force of the spring. Since the spring force can be increased, both the rate of change in roll angle (roll speed) and the amount of change in roll angle when the automobile turns can be suppressed, further improving riding comfort.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An automobile suspension according to a preferred embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic perspective view showing a suspension of 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 associated with the front wheels and the rear wheels, respectively. This suspension 1 and 2
are the springs 3a and 4a and the oleo damper 3, respectively.
Shock absorbers 3, 4 made up of shock absorbers 3b, 4b are provided, and air springs 5, 6 made of suitable elastic material diaphragms are provided around the dampers 3b, 4b. The above dampers 3b, 4
b is a variable damper whose damping force can be adjusted; therefore, the diameter of the orifice provided in the piston (not shown) is variable. In order to change the diameter of this orifice, plungers (not shown) driven by solenoids 7 and 8 are provided in the piston rods 3c and 4c, and the plungers are rotated by the energized solenoids 7 and 8. Therefore, the diameter of the orifice is reduced, the damping force of the dampers 3b and 4b is increased, and the suspension characteristics of the suspensions 1 and 2 are made harder. In addition, air springs 5 and 6
is controlled air chambers 11 and 1 by air pipes 9 and 10.
2, respectively, and these chambers 11 and 12
Solenoid valves 13 and 14 provided at the inlet of
Due to the operation of the air springs 5, 6 and air chambers 11, 12
The communication state between is controlled. In this example, when the solenoids of the solenoid valves 13 and 14 are energized, communication is cut off. When the communication between the air springs 5, 6 and the air chambers 11, 12 is cut off in this way, the effective volume of the air chambers of the air springs 5, 6 decreases, so that the spring force of the air springs 5, 6 becomes stronger. As a result, the suspension characteristics of suspensions 1 and 2 become harder.

The excitation of the solenoids 7 and 8 for adjusting the damping force of the variable dampers 3b and 4b and the solenoid valves 13 and 14 for adjusting the spring force of the air springs 5 and 6 is controlled by the controller 15.
It is carried out by. A steering angle detector 16 is connected to the controller 15, which detects the steering angle θ of the steering wheel H and outputs a steering angle signal S〓 indicating this steering angle. The controller 15 includes, for example, a steering angle detector 1 as shown in FIG.
The steering angle signal S is an analog signal output from 6.
A/D converter 17 which receives the signal and converts it into A/D.
have. The output terminal of this A/D converter 17 receives a steering angle signal S〓 digitized by this A/D converter, and receives a steering angle signal S〓 represented by the following equations (1) and (2). A calculation circuit 18 is connected to calculate a weighted average value (hereinafter referred to as a first weighted average value and a second weighted average value, respectively). In addition,
The weighted average value is for spring control,
θn is for damper control.

=(k-1)θm-1+θ/k...(1) =(l-1)θn-1+θ/l...(2) In the above formulas (1) and (2), -1 and -1 are respectively The weighted average value used in the previous control, k and l each indicate the number of times of weighting, and θ represents the current steering angle indicated by the steering angle signal S〓. Note that the weighted average values -1 and -1 used in the previous control are stored in the storage circuit 19.

After the calculation circuit 18 performs the calculation of the above formula,
The absolute value of the difference between the weighted average value obtained by this calculation and the current steering angle θ | θ
−| and |θ−| are calculated. Next, this calculated absolute value |θ−|
Determination of whether or not the spring force in step 6 is greater than the set value θx at which the spring force should be switched, and the absolute value |θ
-| is larger than θy, which is a set value for switching the damping force of the dampers 3b and 4b. Arithmetic circuit 18, above |θ−|
>θx is YES, a valve signal S _S to operate the solenoid valves 13 and 14 is outputted to the solenoid valves 13 and 14 via the output device 20, and the spring force of the springs 5 and 6 is strengthened. do.
Further, the arithmetic circuit 18 operates as described above |θ−|>θy
When the determination is YES, a solenoid activation signal S _D to activate the solenoids 7 and 8 is outputted to the solenoids 7 and 8 via the output device 20 to increase the damping force of the dampers 3b and 4b. It's getting old.

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 18a, a first differential amplifier 18b, and a first comparator 18c, and a second integrating circuit 18d, a second differential amplifier 18e, and a second comparator 18f. It is equipped with a damper control system. The first and second integration circuits 18a and 18d have time constants corresponding to the weighting times k and l, and receive a steering angle signal S〓 indicating the current steering angle θ from the steering angle detector 16. A weighted average value signal indicating the weighted average value of the steering angle is obtained by inputting the input and substantially performing the calculations of equations (1) and (2) above.
Output S〓 ₀₁ and S〓 ₀₂ . 1st and 2nd above
The differential amplifiers 18b and 18e are the absolute value circuit 18.
b', 18e', weighted average value signals S〓 ₀₁ , S〓 ₀₂ and steering angle detector 16 from integrating circuits 18a, 18d.
The steering angle signal S〓 is inputted from and the above-mentioned |θ−| and |θ−| are calculated from these signals. The comparators 18c and 18f are connected to the |θ−
It is determined whether θm| and |θ−| are larger than θset, which is the set value θx, θy, and when they are larger, the valve actuation signal S _S and the solenoid actuation signal S _D are output.

Next, when the spring force of the springs 5 and 6 and the damping force of the dampers 3b and 4b are controlled by the controller 15 having the above configuration,
Steering angle θ, first weighted average value used to control the spring force of springs 5 and 6, damper 3
Figure 5 shows the relationship between the second weighted average value used to control the damping force of b and 4b, the valve actuation signal S _S , the solenoid actuation signal S _D , the roll angle change a, and the roll angle change rate b. I will explain while referring to it.

First, if the steering angle θ of the steering wheel H changes as shown by the solid line in FIG. 5A, then
The first weighted average value changes as shown by the dashed line in FIG. 5A. For the first weighted average value, it is desirable to increase the number of times k of weighting so that it changes gradually in this way, and to reduce the weight of the current steering angle θ. In the above case, a period in which the difference from θ is greater than the set value θset is a period in which slashing is applied. During the above period, the controller 15 outputs the valve actuation signal S _S as shown in FIG. 5B, closes the solenoid valves 13 and 14, and increases the spring force of the air springs 5 and 6. As a result, the amount of change in roll angle is controlled so as not to exceed a predetermined value, as shown in FIG. 5C.

On the other hand, the second weighted average value changes as shown by the broken line in FIG. 5D. The second weighted average value is
It is desirable to set the number of times of weighting 1 small and to increase the weight of the current steering angle θ so that the current steering angle θ changes relatively rapidly in this way. In the above case, the period in which the difference between θ and θn is greater than the set value θset corresponds to the period marked with a slash in FIG. 5D. Controller 15
During the above period, the solenoid actuation signal S _D as shown in FIG. 5E is output, the diameters of the orifices of the dampers 3b and 4b are reduced, and the damping force of the dampers 3b and 4b is increased. As a result, the roll angle change rate, that is, the roll speed becomes high only at the beginning of turning the steering wheel H, as shown in FIG. 5F, and its magnitude can be suppressed. Therefore, while the automobile is turning, the dampers 3b and 4b are softened, so that the riding 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. are not too precise. Further, there is an advantage that a complicated differential circuit for detecting or calculating the steering angle change rate 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, and FIG.
Figure 3 is a circuit diagram showing the electronic control system of the suspension shown in Figure 1. Figure 4 is the function of the arithmetic circuit shown in Figure 3. FIG. 5 is a time chart for explaining the function of the arithmetic circuit. 1, 2... Suspension, 3b, 4b... Oleo damper, 5, 6... Air spring, 7, 8... Solenoid, 13, 14... Solenoid valve, 1
5... Controller, 16... Rudder angle detector.

Claims (1)

[Scope of Claims] 1. An automobile suspension comprising a variable damping force damper for suspending automobile wheels on a vehicle body and a variable spring force spring, comprising a damping force adjusting means for adjusting the damping force of the variable damper; spring force adjustment means for adjusting the spring force of the variable spring;
A steering angle detection means for detecting a steering angle of a steering wheel, a steering angle signal outputted by the steering angle detection means is inputted, and based on this steering angle signal, a roll angle change rate signal indicating a roll angle change rate, and a roll angle are generated. A steering angle signal processing means that calculates and outputs a roll angle change amount signal indicating the amount of change, and inputs the roll angle change rate signal and the roll angle change amount signal, and calculates the roll angle change rate indicated by the roll angle change rate signal. is larger than a set value, a variable damper control signal that increases the damping force of the variable damper is output to the damping force adjustment means, while when the roll angle change amount indicated by the roll angle change amount signal is larger than the set value, The steering angle signal processing means includes a control means for outputting a variable spring control signal for increasing the spring force of the variable spring to the spring force adjustment means, and the steering angle signal processing means retrogrades the steering angle signal input from the steering angle detection means for a predetermined time period. The system generates a signal based on the difference between the reference steering angle and the actual steering angle, which are average-processed, and in the averaging process,
The suspension of an automobile, wherein the roll angle change rate signal is obtained by comparing the roll angle change amount signal with averaging processing in which the actual steering angle is weighted more heavily than the reference steering angle.