JPS5973312A - Suspension of car - Google Patents

Abstract

PURPOSE:To provide optimum manipulating characteristic depending upon a steering angle, by constituting a device such that a damper unit, having a variable damping force, is mounted to a suspension means, and the damping force ratio between damper units for front and rear wheels is varied according to the output of a steering angle sensor. CONSTITUTION:The detected output of a steering angle sensor 5 is inputted to a controller 3. When the inputted steering angle signal exceeds a given value, the controller 3 outputs signals to actuators 1a and 2a, to decrease the damping force CF of a damper unit 1b of each of front wheels, and to increase the damping force CR of a damper unit 2b of each of rear wheels. Thus, CF/CR is decreased, and understeer is weakened. Conversely, in the case of non-steering, the CF/CR is kept at a large value, and under steer is strengthened. This provides optimum manipulating characteristic depending upon a steering angle.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automobile suspension, and more particularly to an automobile suspension that includes a damper with variable damping force and that controls the damping force depending on the situation.

In automobile suspensions, a system that controls the damping force of a damper according to the situation is, for example, as shown in Japanese Utility Model Application No. 109008/1983, which constantly changes the damping force according to the vehicle speed. Vehicles designed to obtain favorable handling characteristics are known. This enhances understeer characteristics at high speeds, and provides neutral steer or weak oversteer characteristics at low speeds, ensuring stable handling characteristics at all times in response to changes in vehicle speed.

However, there are various factors other than vehicle speed as changes in the situation that require changes in handling characteristics. For example, the width of the steering angle is also closely related to the required maneuvering characteristics.
It is desirable that the understeer characteristics be weaker when turning the wheel significantly. That is, it is desirable that the understeer characteristic be weakened when the steering angle is large, and strengthened when the steering angle is small. Therefore, sufficient running stability cannot be ensured only by control according to vehicle speed.

For example, when you turn the steering wheel suddenly and change the direction of the car significantly, the understeer characteristics are weakened and approaching oversteer results in better response and better steering control. However, when the vehicle is traveling straight without turning the steering wheel, it is desirable to have strong understeer characteristics because it improves straight-line performance. The understeer characteristic is particularly effective in correcting disturbances when the car is subjected to disturbances, and when this characteristic weakens, the straight-line stability decreases, making the car dangerous, especially at daytime speeds. Therefore, when the steering angle changes, it is desirable to always be able to obtain an appropriately strong understeer characteristic.

The present invention has focused on this point, and has as its object to provide an automatic military suspension that can always provide desirable handling characteristics as the steering angle changes.

In order to achieve this objective, the suspension of the present invention is characterized in that the damping force of the damper is made variable, and this is controlled in accordance with changes in the steering angle, so that desired steering characteristics are always obtained. .

That is, in the suspension system of the present invention, a damper unit that changes the damping force by changing the fluid passage area in the damper is provided on at least one of the front wheel and the rear wheel among the front and rear wheel suspensions, and the damping force of this damper unit is changed. It is controlled by electromagnetic means, and this electromagnetic means is
Control that receives the output of a steering angle sensor that detects the steering angle and outputs a control signal that makes the ratio of the damping force of the front wheel damper unit to the damping force of the rear wheel damper unit smaller during steering than when not steering. It is characterized in that it is controlled by means.

Here, making the ratio of the damping force of the front wheel side damper unit to the damping force of the rear wheel side damper unit smaller during steering than when not steering means that the damping force on the front wheel side is constant.
When steering, you can increase the damping force on the rear wheels, or conversely, you can keep the rear wheels constant and decrease the damping force on the front wheels, and you can change both in the opposite direction, i.e., decrease the front wheels and increase the rear wheels. (In each case, the damping force is changed in the opposite direction to the above when the vehicle is not being steered.)

Hereinafter, to simplify the explanation, the damping forces of the front and rear wheel damper units will be expressed as CF and CR, respectively. The ratio of CF to CR is CF/CL (.

Therefore, the above three cases mean that the CF during steering is
This means that CF/C is smaller than CF/C during non-steering. This can be expressed as shown in Table 1.

Table 1 When CF/CR is decreased, the understeer characteristics are weakened, so it is possible to weaken the understeer characteristics during steering and improve steering control. In the present invention, as described above, the CF/CR is changed depending on the magnitude of the steering angle, so that desirable understeer characteristics can always be obtained, and good maneuverability and running stability can be realized.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 shows an automobile equipped with a suspension according to an embodiment of the present invention, and FIG. 2 shows a system diagram of its main parts. In this embodiment, front wheel suspension 1.1,
A damper unit with variable damping force is provided for each of the rear wheel suspensions 2, 2, and these are controlled by a controller 3. The controller 3 receives the output from a steering angle sensor 5 provided on the steering wheel 4 and detects the magnitude of the steering angle through a lead wire 3a, and connects the front and rear wheel suspensions 1, 1 with built-in damper units with variable damping force. , 2.2 through lead wires 3b and 3c. Furthermore, in this embodiment, the output from the speedometer 6 is also input through the lead pin 3d.

Further, an auto/manual changeover switch 7 is connected to the controller 3 through a lead wire 3e.

As shown in Figure 2, each suspension 1°1.2.2
actuators la, la, 2a consisting of electromagnetic means
, 2a, damper unit 1 b, 1 b, ' 2 b, 2 b, and this damper unit whose damping force can be changed by this damper unit) 11), 1 b, 2 b, 2
a coil spring lc that further supports spring b;
lc, 2C.

2C is provided, and the output from the controller 3 which receives the signal from the steering angle sensor 5 is sent to the actuators la, La, 2a of the left and right front and rear wheel suspensions 1, 1, 2.2 through the leads 113b and 3C. , 2a. The actuators la, la, 2a, 2a that receive this output, that is, the control signal, control the damping force of the damping force variable damping units lb, lb, 2b, 2b to a magnitude corresponding to the steering angle.

For example, when the steering angle sensor 5 detects a steering angle equal to or greater than a predetermined value and outputs a signal (voltage equal to or greater than a predetermined value) indicating a large steering angle, the controller 3 receiving the signal outputs a signal to the actuator 1a, 1a, 2a, 2a to reduce the fluid reduction force (CF) of the front wheel damper units 1-2b, 2b, and reduce the damping force (CF) of the front wheel damper units 1-2b, 2b.
CR) is increased, thereby decreasing CF/(, '1 likelihood.

Specifically, as shown in FIG. 3, for example, when the output of the steering angle sensor 5 exceeds a predetermined value, the positive input of the comparator 3A of the controller 3 becomes large, outputting a negative output (H), and this comparator The base voltage of the transistor 3C connected to the output to the comparator 3 is increased to turn off the transistor 3C by lowering the pace voltage of the transistor 3C connected to the output to the comparator 3 via the inverter 3B. is turned on, and the front wheel side actuators la and la (solenoids of electromagnetic means) connected to the collector side of the former transistor 3C are demagnetized to reduce the deformation force (CF) of the front wheel side suspensions 1 and 10. In addition, the latter transistor 3
Rear wheel side actuator 2a connected to the collector side of D
, 2a (solenoid of electromagnetic means) to increase the damping force (CR) of the rear wheel suspensions 2, 2, thereby cF7c1. (can be made smaller to weaken the understeer characteristics (standard understeer).

In the straight-ahead state, the output of the steering angle sensor 5 is below a predetermined value, so the output to the comparator 3 becomes a low output (L), and the transistor 3C connected via the inverter 3B is turned on to increase the damping force ( CF/C
By increasing 1, the understeer characteristics are strengthened.

Note that the output of the speedometer 6 (FIGS. 1 and 2), which is a vehicle speed sensor, is input to the controller 3 together with the output of the steering angle sensor 5, and in addition to the above-mentioned reducing force control by the steering angle sensor 5. , which enables control according to vehicle speed. Control according to vehicle speed means, for example, as is conventionally known, control to strengthen understeer characteristics at high speeds, that is, control to vehicle speed (V) in contrast to control to steering angle (θ). control, and control that weakens understeer characteristics as the vehicle speed increases during steering. In other words, in order to suppress roll due to centrifugal force during steering, the steering angle (θ) is multiplied by the square of the vehicle speed (V2). There are two possible control methods that weaken the understeer characteristics depending on the magnitude of (2).

Although the output of the vehicle speed sensor 6 is not used in Fig. 3, the output of the vehicle speed sensor 6 is not used.
In the embodiment shown in FIGS. 5 and 5, examples of the above two types of control using the output of the vehicle speed sensor 6 will be explained. (The embodiment shown in Fig. 5 is the one in the previous work that controls the steering angle and vehicle speed in the opposite direction, and the embodiment shown in Fig. 4 is the one that controls the steering angle and vehicle speed in the opposite direction.
This will be explained using the example shown in the figure. ) In addition to the above-mentioned automatic automatic control, the auto-manual changeover switch 7 also enables manual control when it is desired to manually change the damping force ratio (C-F/CR) of the front and rear wheels. .

Next, FIG. 4 shows an embodiment of Rin 2. In this example,
The output θ of the Casarel steering angle sensor 5 is input to the controller 3o.
and the output S of the vehicle speed sensor 6, the steering angle θ is unchanged, and the vehicle speed V is a converter 31 that converts the output S of the vehicle speed sensor into a voltage.
The output V converted by is multiplied by the multiplier 32 and summed up to V2, and then input to the multiplier 33 to obtain θ×v2, and this output θ×V2 is sent to the buffer 34a and amplifier 34b.
The damping force is transmitted to the actuators la and 2b of the front and rear wheels through the damping force to control the damping force. In other words, vehicle speed (g)
The square of the value multiplied by the steering angle (θ) determines the damping force front and rear wheel ratio CF7cr? .

The size of is controlled so that the larger this value (θ×■2), the smaller it becomes. Due to this, the reduced force control side 1 for the steering angle multiplied by the influence of centrifugal force proportional to the square of the heavy speed.
can be done.

Next, an embodiment will be described in which the damping force of the front and rear wheels is controlled ILυ according to a combination of vehicle speed and steering angle.

This third embodiment performs basic control 1 of reducing the magnitude of CF/CB during steering, and also changes the magnitude of CF/Cl(,) depending on the heavy speed. That is, cF/C1t is made larger at high speeds than at low speeds to strengthen the understeer characteristics at high speeds.This relationship can be expressed as shown in Table 2.

In Table 2, "soft" means that the damping force (CF, CB) is small, and "hard" means that the damping force is large. Therefore, Table 2 shows that the understeer characteristics are weakened by changing the rear wheel damping force (Cit) from soft to hard when steering both at single speed and at high speed. When the vehicle becomes high, the damping force (Ci'') of the front wheels is changed from soft to hard to strengthen the understeer characteristics.

A circuit diagram of such an embodiment is shown in FIG.

As is clear from FIG. 5, the output from the vehicle speed sensor 6 is input to the first comparator 36 of the controller 35, which turns on and off the first transistor 37 connected to the output of the first comparator 36. , the actuator 1 of the front wheel suspension 1 connected to this
a, ], a is controlled. (First comparator 3 at high speed
On the other hand, the output of the steering angle sensor 5 is input to the second comparator 38, which turns the second transistor 39 on and off. , which controls the actuators 2a, 2a of the rear wheel suspension 2 connected thereto. (During steering, the output of the second comparator 38 becomes H, and turning on the actuator changes the soft to hard.) Next, a specific example of a damper unit with variable reduction force is shown in FIG. This will be explained in detail with reference to Figure '7.

As shown in FIG. 6, the suspension 2 has an upper end fixed to a part 10 of the vehicle body via an elastic body 11, and has an air chamber 12.
An upper case 13 forming an upper case 13, a lower case 16 consisting of an outer cylinder 14 and an inner cylinder 5 built into the lower end of the upper case so that the upper end can go in and out, and the insides of the upper and lower cases 13 and 16 are airtightly connected. connecting body 17 and upper and lower cases 13.1
6 coaxially penetrating the inside of the lower case 16 and slidable up and down with respect to the inner cylinder 15 of the lower case 16, and a main valve fixed to the lower end of the piston rod 18;
A bottom valve 20 is fixed to the lower end of the inner cylinder 15, and the main valve 19 divides the oil chamber in the inner cylinder 15 into eight parts above the main valve 19 and 13 parts below the main valve 19. The oil % C between the inner cylinder 15 and the inner cylinder 15 is communicated with the upper end of chamber A at the upper end, and with the lower end of chamber B at the lower end. Further, a control rod 21 is arranged above and below the center of the piston rod 18, and this control rod 21 has an upper end 21. a is engaged with a rotation key 22 which is rotated by an external force so that rotational force can be transmitted thereto. A lower end portion 188K of the piston rod 18 is connected to the lower end portion of the control rod 21 so as to communicate A% and Bg.
An orifice 21b is provided which communicates with the V-shaped communication hole 18b, and the rotation of the control rod 21 turns on and off communication between the orifice 21b and the communication hole 18I of the lower end portion 18a of the piston rod.

Details of the structure of the lower end of the main rod 18 including the lower end of the control rod 21, the main valve 19, and the bottom valve 20 will be described later with reference to FIG.

The relative vertical movement of the upper case 13 and the lower case 16 is caused by the air spring provided by the air chamber 12, as well as by the two lower cases 13,
Upper and lower spring cases 13a and 16 fixed to 1.6
It is elastically absorbed by the spring 30 (2C in FIG. 2) held between the parts a and a. Brackets 16b and 16c fixed to the outer surface of the lower case 16 are for fixing the wheel support structure including the wheel knobs that rotatably support the wheels, so that the wheels are attached to the L portion 10 of the vehicle body. It is held so that it can move up and down. That is, the single unit is suspended on wheels,
It is elastically supported so that it can move up and down.

As mentioned above, the damper unit is constituted by the constructed suspension T, A, B, and CD in the T case 16, and the communicating passages and grooves that communicate these. The details of the structure of the damper unit that generates the damping force will be explained below with reference to FIG.

As shown in FIG. 7, the main valve 19 is formed with an orifice 19a on the sardine side and an orifice 19b on the elongation side.
Valve in each orifice 19a, 19b], 9c
, 1.9d are provided. Similarly, the bottom valve 20 has a contraction side orifice 20a and an expansion side orifice 201.
) are formed, and each is provided with a valve 20C220d. In the main valve 190 portion where the A chamber and the B chamber are adjacent, if the damping force is to be increased, the orifice 19a,
Only the orifice 21b at the lower end of the control rod 21 and the communication hole 18b at the lower end 18a of the piston rod 18 need to be rotated L'' to reduce the damping force. is in communication with the orifice 21b at the lower end of the control rod 21.
Room A and B are communicated with each other through a communication hole 18A- which is opened from the inside to Bz. Therefore, A\ and B
The fluid passage area between the chambers becomes large and the damping force of this damper unit becomes small.

The control rod 21c is rotated by rotating the engaged rotation key 22 (for example, 901i), thereby connecting the orifice 21b and the communication hole 1.
8b is turned on and off. The rotation key 22 is driven and rotated by electromagnetic means such as a solenoid, and performs variable control of the damping force of the damper unit.

When using the damper unit with the above configuration on the rear wheel side, the orifice 21b of the control rod 21 is turned off during steering to reduce the fluid passage area between the A chamber and the B chamber. When the steering angle sensor detects a large steering angle, the orifice 21b is turned on to increase the area and reduce the damping force. Furthermore, when using this for the front wheels, the orifice 21b is turned on during steering and turned off when the vehicle goes straight. Furthermore, when this is used inside the front and rear wheels, the above two types may be used in combination as they are.

The automobile suspension according to the present invention uses a damper with variable damping force as described above, and controls this according to changes in the steering angle to reduce CF/C)t during steering. The understeer characteristic, which is weakened when the vehicle is not being steered, can be maintained at a desired level, and stable driving can be achieved regardless of changes in the steering angle.

In the above embodiment, the magnitude of the damping force is switched between two types, large and small, but this is due to the difference between the orifice 21b and the communication hole 1.
By continuously changing the communication cross-sectional area of 8b, it can be changed continuously, and if the output of the steering angle sensor is also a continuous analog value, it can be changed in response to subtle changes in the steering angle. Continuous control is also possible. Of course, it goes without saying that multistage control in which this is divided into three or more stages is also possible.

[Brief explanation of drawings]

Figure 1 shows an outline of an automobile equipped with the suspension of the present invention.
Figure 116 and Figure 2 are system diagrams of embodiments of the suspension of the present invention, Figures 3 to 5 are circuit diagrams showing specific examples of Figure 2, and Figure 6 is a system diagram of an embodiment of the suspension of the present invention. FIG. 7 is a cross-sectional view showing an example of a damper unit according to the present invention, and FIG. 7 is a cross-sectional view showing the main part of FIG. 6 in detail. 1.2... Suspension la, 2a... Actuator 3... Controller 5.
......Steering angle sensor 6...
・・Single sensor 7・・・Auto manual changeover switch 1
2... Air room 13...
・・Upper case 14・・・・・Outer tube 15
・・・・・・・・・Inner cylinder 16・・・・・・・・・
Lower case 18...Piston rod]9...Main pulp 20...
...Bottom pulp 18b...Connection
Hole 21... Control rod 21b.
...Orifice 22 ...Rotation key
-Figure 1 Figure 2

Claims (1)

[Claims] By changing the suspension means for suspending the original body on the front wheel and the rear wheel, respectively, and the fluid passage surface 48 provided on at least one of the front wheel and the rear wheel among the suspension means,
A damper unit that changes the damping force, a damper unit that changes the fluid passage surface of this damping unit, a steering angle sensor that calculates the steering angle, and a damping unit on the front wheel side that receives the output of this steering angle sensor. A suspension for an automobile comprising a control means for inputting a control signal to the electromagnetic means to make the ratio of the damping force of the damper unit to the damping force of the rear wheel side damper unit smaller during steering than when not steering.