JPS611519A - Suspension control device - Google Patents

Abstract

PURPOSE:To improve the comfortableness to drive a three-step damping force variable car and its operating stability by determining running and road surface states from upper and lower oscillation acceleration, steering, and car speed signals in a suspension for the car and controlling them according to the size of the upper and lower oscillation acceleration signal. CONSTITUTION:An upper and lower oscillation acceleration signal G is input to a logic circuit 8 through a low pass filter 4, comparator 5, and delay circuit 6 and processed and a steering signal S is input to it through a delay circuit 7 and processed and then a car speed signal V is input directly to it. Road surface and running states are determined, 8-step environmental conditions are combined and determined, hard H, normal N, or soft S signals are output, and then a damper 16 is controlled in three steps through an actuator 15. In other words, when the upper and lower oscillation acceleration signal is low, the damper is controlled to the N or H and when it is high, the damper is controlled to the S or N. As a result of this structure, damping force can be controlled according to the running and road surface states, laying stress on the comfortableness to drive a three- step damping force variable car and its operating stability.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) Undeveloped IJI relates to suspension control devices for vehicles.

(Background technology) As a method to ensure ride comfort and handling stability of a vehicle, a manual control type in which the driver switches the manual sweep and changes the damping force of the damper using an actuator such as a motor or a damper is used. There is an automatic control type that detects the condition and automatically changes the damping force, and there is also a manual suspension control device that variably controls the damping force in three stages: hard, normal, and soft. .

However, in the past, the steering operation state and the final speed m
Since the damping force is only automatically controlled according to the driving conditions caused by the driver's operations, it has not been possible to variably control the damping force in accordance with changes in road surface conditions.

(Object of the Invention) The object of the present invention is to focus on the correlation between the road surface condition and the vertical vibration acceleration of the vehicle body in a vehicle in which the damping force of the damper is automatically variably controlled in three stages. The damping force can be automatically variably controlled to follow changes in road surface conditions, and the damping force variable range changes between normal and hard, with emphasis on handling, especially when driving on relatively good roads. Another object of the present invention is to provide a suspension control device in which the damping force variable range is set to normal and soft when driving on a relatively bad road surface, with emphasis on riding comfort.

(Structure of the Invention) In order to achieve the above object, the present invention provides a sensor for detecting vertical vibration acceleration of a vehicle body, a sensor for detecting a steering operation state, a sensor for detecting vehicle speed, and signals from these three types of sensors. The system consists of a control circuit that inputs a signal and outputs a three-stage signal depending on the road surface and driving conditions, and a drive device that automatically switches the damper's damping force between hard, normal, and soft in response to the output signal. The present invention is characterized in that a suspension control device is configured to automatically and variably control the damping force to normal and node when the vertical vibration acceleration of the vehicle body is small, and to normal and soft when the acceleration is large.

Then, when driving on a relatively good road surface, the damping force is controlled to hard to suppress the roll rate only when the steering angle is relatively large while driving at high speed, and when driving on a relatively bad road surface, the damping force is controlled to hard to suppress the roll rate. When the vehicle is running at a relatively high speed and the steering angle is relatively large, the damping force is controlled to normal while suppressing the roll rate while taking both ride comfort and steering stability into consideration.

(Embodiment) A preferred embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

Fig. 2 is a vertical cross-sectional view of the main part showing an example of a hydraulic damper, in which a piston (23) is slidably fitted into a cylinder (22) set up in a bottom tube (21), and is vertically movable. Piston (2) with piston valves (24) and (25)
3) Inside the piston rod (26) is an adjustment row,
(27) is rotatably installed vertically, and the adjustment rod (27)
27) A potentiometer (28) and a DC motor (29) are connected to the upper end.

An oil hole (31) is provided in a portion of the piston rod (26) above the piston (25), and a select valve case (32) is provided at the lower end of the piston rod (26) that projects downward from the piston (25). , this case (32
) A check valve (33) is installed inside the check valve (33), and a select valve (34) is provided at the lower end of the adjustment rod (27) facing above the check valve (33).

As shown in FIGS. 3 and 4, the peripheral wall of the valve case (32) has vertically elongated openings (35) facing each other in the radial direction.

(35), and four oil holes (36)... are provided radially in the earthen wall of the select valve (34).
Furthermore, on the peripheral wall of the select valve (34), three sets of orifices (37), (37
).

(38), (3B), (39), and (39) are provided. Namely, large orifice (37), medium orifice (38),
Three types of small orifices (38) are provided, and these are two-stage orifices (3) above and below the check valve (33).
7a), (37b).

(3tla), (38b), (39a),
(39b).

To describe the operation of such a variable damping force hydraulic damper, the select valve (34) is rotated by the motor (29) via the potentiometer (28) and the adjustment rod (26), and is at its stop position, i.e. Select valve (3
Each orifice (37) of 4)... is connected to the valve case (3).
Detection of the position matching the opening (35) in 2) is performed by a potentiometer (28).

Since the check valve (33) is pushed up, the damping force when the piston speed on the tampon contraction side is low is the orifice (37a) at the upper stage of the select valve (34)...
and the lower orifice (37b)...
In the high speed range, this occurs at the piston valve (24) and the lower orifices (37a), (37b), etc.

In addition, the damping force in the low speed range of the extension side piston speed is generated only by the upper orifice (37a) of the select valve (34) because the check valve (33) acts, and in the middle and high speed range It occurs at the valve (25) and this upper orifice (37m)...

Therefore, the select valve (30 orifices (37)).

By selecting (38) and (39), the damping force is
As shown in the characteristic diagram in Figure 5, the medium orifice (38) is normal (N), and the large orifice (37) is soft) (S).
), and the small orifice (39) is variably controlled in three stages: hard (H).

Next, the control circuit will be explained based on FIG.

(1) is a sensor (hereinafter referred to as G sensor) that detects the vertical vibration acceleration of the vehicle body corresponding to changes in road surface conditions and vehicle speed;
(2) is a sensor that detects each steering wheel 15I (hereinafter referred to as S sensor), and (3) is a sensor that detects vehicle speed (hereinafter referred to as V sensor).

The output signal from the G sensor (1) is filtered through a low-pass filter (
4), outputs a signal with relatively low frequency components necessary to know the road surface condition, and inputs it to the comparator (5). is [0] signal, delay times 1 & (8)
This input signal is provided with a certain delay time and is input to the N07 circuit (8) of the logic circuit (8). Here, the delay circuit (9) is provided to delay the road surface with joints.

The output signal +31 from the S sensor (2) is set to a certain predetermined value of 1 or more as a [l] signal, and less than a certain value as a [01 signal, and is input to the delay circuit (7), and this input signal is given a certain delay time. establish. The output signal V from the V sensor (3) is set to a certain predetermined value V, and those above are [11] and those below are [01], and both of these signals are input to the AND circuit (10) of the logic circuit (8). . Here, the delay circuit (7) is provided to delay play in the steering wheel.

Then, the signals of the N07 circuit (9) and the AND circuit (lO) are transferred to the +AND circuit (11), the XOR circuit (lO), and the N07 circuit (lO).

It is input to 8 circuits (13), and each output terminal has a damping force [
)1], [N], and [Sl.

Such output signal is inputted to the actuator drive circuit (14), which operates the actuator (15), ie, the motor (29), which drives the select valve (34) and the orifices (37), (38), (39). ) and damper (1
6) The damping force is automatically controlled to hard (H), normal (N), or soft (S).

In the above, when the vertical vibration acceleration q of the vehicle body is greater than the set value 1, that is, it is large, the output signal of the logic circuit (8) is set to [8
1 and [Sl only, if small, [N] and [)l]
Only.

The truth table is shown below along with the road surface and driving conditions, that is, the environmental conditions.

Next, each environmental condition will be explained.

First of all, conditions 1 to 4 are when driving on a relatively good road surface and have little effect on ride comfort, so we focused on steering stability and changed the damping force between normal (N) and hard (H). ■Make it a variable area.

Condition 1 for tel is low speed driving and straight-line condition, so I
For NF, condition 2 is high speed driving, but because it is going straight,
In the same <(N), condition 3 is a cornering g, but since it is running at a low speed, the roll rate is small, so it is 1 length for the same [N].Condition 4 is a cornering state while driving at high speed, and the roll rate is small. Since it is large, 1. In order to suppress the roll rate, we automatically control the number of rolls to [H].

Conditions 5 to 8 are when the vehicle is traveling on a relatively bad road surface, so ride comfort is emphasized and the damping force is set in a variable range between normal (N) and soft (S).

In other words, condition 6 is a high-speed driving condition, but since it is a heavy speed condition, the condition 6 is a turning condition, and condition 7 is a cornering condition.
Since it is running at low speed, the roll rate is small, so a similar [
In condition 8, roll rate occurs when cornering while driving at a relatively high speed, but in this case, the vehicle speed is generally lower than when driving on a relatively good road surface, so the roll rate is suppressed while suppressing the roll rate. Automatic control is performed to [N] in consideration of both riding comfort and handling stability.

Note that the variable damping force type hydraulic damper is not limited to the one in the embodiment, and of course any arbitrary one can be adopted.

(Effects of the Invention) As described above, according to the suspension control device of the present invention, the vertical vibration acceleration sensor of the vehicle body, the steering sensor, the vehicle speed sensor, and their signals are inputted to respond to the road surface and driving conditions. It consists of a control circuit that outputs a three-step signal, and a drive device that receives the output signal and automatically switches the damping force of the tamper between hard, normal, and soft.
It not only monitors the driving state by detecting the steering operation state and vehicle speed, but also tracks changes in road surface conditions by detecting the vertical vibration acceleration of the vehicle body. The damper's damping force can be automatically variably controlled between hard and normal 5 to soft in response to changes in environmental conditions.Especially when driving on a relatively good road surface, the system eliminates the soft damping force in order to emphasize maneuverability. , with a variable range of damping force between normal and hard, and when driving on relatively bad roads, remove hard to emphasize ride comfort.
The damping force can be automatically controlled between normal and soft damping force variable ranges. Furthermore, when driving on a relatively good road surface, the damping force can be controlled hard only when the steering angle is relatively large while driving at high speed. Therefore, it is possible to suppress the roll rate when cornering at high speed on a good road surface, and when driving on a relatively bad road surface, the damping force is applied only when the steering angle is relatively large while driving at a relatively high speed. Since it is controlled normally, it is possible to ensure both ride comfort and handling while suppressing roll rate during rough road surfaces and high-speed cornering.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the control circuit, and Fig. ff12 is a vertical cross-sectional view of main parts showing an example of a hydraulic damper. Figure 3 is a vertical sectional view of the select valve part, Figure 4 is a sectional view taken along the line ■-■ in Figure 3,
FIG. 5 is a damping force characteristic diagram. In addition, (27) in the drawing is an adjustment rod, (28) is a potentiometer, (29) is an actuator, (3
2) is the valve case, (34) is the select valve, (3
? ). (38) and (39) are orifices, and (8) is a logic circuit.

Claims (2)

[Claims] (1) The damping force of the damper can be set to hard, normal, or soft.
In a vehicle suspension that is controlled in stages, signals from three types of sensors are input: a sensor that detects the vertical vibration acceleration of the vehicle body, a sensor that detects the steering operation status, and a sensor that detects the vehicle speed. a control circuit that outputs signals in three stages depending on the road surface and driving conditions; and a drive device that automatically switches the damping force of the damper in response to the signal from the control circuit, and A suspension control device characterized in that the damping force is automatically variably controlled between normal and hard when the damping force is small, and between normal and soft when the vertical vibration acceleration of the vehicle body is large. (2) In claim 1, when the vertical vibration acceleration of the vehicle body is small, the damping force is set hard only when the steering angle is relatively large during high-speed driving, and when the vertical vibration acceleration of the vehicle body is large. In this case, the suspension control device controls the damping force to normal only when the steering angle is relatively large while driving at relatively high speeds.