JPH01266010A - Suspension control device for vehicle - Google Patents

Abstract

PURPOSE:To increase the grounding load of a slipping wheel to quickly end and dissolve the slipping of the wheel when the wheel is slipping by increasing a stroke between spring weight and unspring weight. CONSTITUTION:A vehicle is provided with a regulating means A for a stroke between spring weight and unspring weight and a detecting means B for the slip of a wheel. In addition, a means C for controlling the means A when the means B has detected the slip of the wheel is provided, namely when the wheel is slipping, the means C increases the stroke between the spring weight and the unspring weight to increases the grounding load of the slipping wheel. Thus the slip of the wheel can be quickly ended and dissolved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a suspension control device for a vehicle (Prior Art) In modern vehicles, there is a gap between the sprung weight and the unsprung weight, e.g. Some vehicles are designed to adjust the stroke between the unsprung weight and the unsprung weight by interposing a stroke adjusting means (also considered as a vehicle height adjusting means) such as a hydraulic cylinder. for example.

In the device disclosed in Japanese Patent Application Laid-Open No. 61-202913, vehicle height detection means are provided on both front axles, so that when one of the left and right front wheels passes through a concave or convex portion, the vehicle height is detected diagonally to the front wheel that has passed through the concave and convex portion. A vehicle has been proposed in which the vehicle height of a certain rear wheel is raised or lowered to reduce rolling of the vehicle.

Incidentally, recently, wheel slip has been increasingly controlled using ABS (anti-lock brake system) or traction control.

This 8BS prevents the wheels from locking during braking, and when the rotational speed of the wheels becomes too low, it is assumed that the wheels are slipping and the braking force is weakened.

Furthermore, traction control is intended to prevent the driving wheels from slipping excessively on the road surface when starting or accelerating, thereby obtaining effective propulsive force. Therefore, in traction control, when the rotational speed of the wheel becomes too high, it is assumed that the wheel is in a slip state, and the torque applied to the driving force is weakened (
(for example, adding braking force or reducing engine output).

(Problems to be Solved by the Invention) When performing slip control such as the above-mentioned ABS or traction control, the problem is how quickly the wheel slip can be brought to a conclusion. For this reason, although various improvements have been made to the GEM control system, there is a limit to how quickly the slippage of the heavy wheels can be brought to a close by using ABS control alone or traction control alone.

Therefore, an object of the present invention is to provide a suspension control device for a heavy vehicle that can quickly resolve slippage of heavy wheels.6 (Means and effects for solving problems) 1. In order to achieve the first objective, the present invention uses a lower stroke adjustment stage interposed between the spring L heavy electric current and the unsprung type electric current, and when the wheel is in a slipping state, this stroke adjustment is performed. The B stage is controlled to increase the stroke between the spring t't it and the unsprung Ichiharu, that is, to increase the ji before the slipping wheel touches the ground.Specifically, As shown in the block diagram in FIG. 4, there are a stroke adjusting means for adjusting the stroke between the spring market amount and the spring sales amount; a slip detecting means for detecting wheel slip; and a wheel slip detecting means. stroke control means for increasing the ground load of the slipping wheel by controlling the stroke adjustment means to increase the stroke between the upper and lower springs. The composition is as follows.

In this manner, in the present invention, the ground load of the wheel in which the slip has occurred is increased, so that the slip of the wheel is promptly contained.

(Embodiments) Hereinafter, embodiments of the present invention will be described based on the attached drawings.

In Figure 1, a car 1 has drive wheels on the left and right sides 1) 1
It has four middle wheels: one wheel 2, 3 and left and right rear wheels 4.5 serving as driven wheels. An engine 6 as a power source is mounted on the front of the car, and the torque generated by the engine 6 passes through a clutch 7, a transmission 8, and a differential gear 0 before being sent to the left and right drive shafts + I L
, 11 [(via the left and right front wheels as driving wheels 2.3
transmitted to. In this way, car l is dollar l? (front engine, front drive).

The engine 6 as a power source is connected to the intake passage 1 of
Throttle valve installed in 2! 3, load control, that is, control of generated torque is performed. More specifically, the engine 6 is assumed to be a gasoline engine, and the generated torque changes depending on the change in the amount of intake air, and the intake air (2) is adjusted by the L throttle valve 13. Then, the throttle valves 1:3 are operated by the throttle actuator 14.
Opening and closing is controlled electromagnetically. Note that the throttle actuator 14 may be constituted by, for example, a DC motor, a step motor, or an appropriate device driven by fluid pressure such as oil pressure and controlled electromagnetically.

Each wheel 2-5 has a brake 21, 22, 23, respectively.
Alternatively, 24 are provided, and each of the brakes 21 to 24 is a disc brake. As is known, this disc brake includes a disc that rotates together with the wheel and a caliper. This caliper holds the brake pads and is equipped with a wheel cylinder.
．． Braking force is generated by pressing the brake pad against the disc with a force that corresponds to the magnitude of brake fluid pressure supplied to the wheel cylinder.

The mask cylinder 27 as a brake fluid pressure generation source is 2
It is of a tandem type having two discharges D 27 a and 27 b. Brake piping 28, 29 extending from each discharge port 27a, 27b is connected to a hydraulic pressure control unit: 30, and from this hydraulic pressure control unit 3o, 4
The brakes 21 to 24 are individually and independently connected to each other by pipes 31 to 34. Of course, the brake fluid pressure generated in the mask cylinder 27 depends on the amount of depression of the brake pedal 35 (depressing force) caused by the driving MD.

The hydraulic pressure control unit 3o has an electromagnetically controlled valve in addition to a pump as a brake fluid pressure generation source, and has a brake fluid F4 for each brake 21 to 24.
- It has the function of independently reducing and maintaining intravenous pressure. Note that the mechanism itself having such functions is well known as ABS and traction control have already been put into practical use, so further detailed explanation will be omitted.

On the other hand, each wheel (spring π) 2 to 5 and vehicle body B (spring π)
A hydraulic cylinder 41 as a stroke adjusting means is interposed between the pump and the pump. This hydraulic cylinder 41 has two chambers 43, 44 defined by a piston 42, and each chamber 4:3, 44 is connected to an electromagnetic control valve 47 via a pipe 45 or 46. A supply pipe 49 to which a pump 48 is connected is connected to the control valve 47, and a relief pipe 50 is also connected thereto. control valve 4
7, the piping 45 and 49 are communicated with each other, and the piping 46 and 50 are communicated with each other, so that the piston 42
is lowered and the vehicle height is increased by -t-+4 (large stroke).

Conversely, when the pipes 45 and 50 are communicated with each other, and the pipes 46 and 49 are also communicated with each other, the piston 42 moves to L'i? -The vehicle height decreases (small stroke). And both pipes 45
By closing both piping 49.5o and 46 (both are out of communication with the piping 49.5o, the piston 42 is stopped), the vehicle height is maintained constant.

Toukij 50 in Figure 1 is a control unit configured using a digital or analog computer, more specifically a microcomputer. This control unit 5
0, signals from each sensor 51 to 57 are input manually, and the control unit 50 sends signals to the actuator 14, hydraulic control unit 30. It is output to the control valve 47. The sensors 51 to 54 each independently detect the rotational speed of each wheel 2 to 5. The sensor 55 detects the stroke position of the piston 42, that is, the mid-height. The sensor 56 detects the pre-ground contact type of the small wheel. The sensor 57 detects the operation amount of an accelerator pedal (not shown), that is, the accelerator opening degree. Of course, sensors 55 and 56 are provided for each wheel. Note that the control unit 50 basically includes CPU, ROM, RAM,
In addition to the CLOCK, it also has an input/output interface and, if necessary, an A/D or l)/A converter, but these are known configurations when using a microcomputer, so a detailed explanation is omitted. Omitted.

Next, the contents of the control unit 50 will be explained.

First, the control unit 50 determines a target throttle opening according to the accelerator opening based on the basic throttle characteristics created and stored in advance, and operates the actuator 14 to achieve this target throttle opening. Drive control.

The control unit 50 performs traction control. In this traction control, the slip rate S of the driving wheels is
TR is found based on, for example, the following equation (1).

WD -WL S' [7=□... (1) WD WD: Number of rotations of driving wheels (2, 3'5) WL: Number of rotations (heavy speed) of driven wheels (4, 5) As the rotational speed of the driven wheels in equation (1), for example, the average value of the rotational speeds of the left and right rear wheels 4.5 is used.
) As is clear from the equation, the greater the slip ratio STR, the greater the slip rim of the drive wheels relative to the road surface. When this slip ratio STR becomes greater than 1, for example 0.2, traction control is started and the torque applied to the drive wheels is reduced. In order to reduce the torque applied to the driving wheels, in the embodiment, the torque generated by the engine is reduced, more specifically, the throttle valve 13 is driven in a direction to be throttled, and the brake force is controlled not based on the basic throttle characteristics. This is done by adding . Then, the target slip ratio for reducing the applied torque is set to, for example, 0.06. In this case, when the slip ratio STR is large (for example, 0.09 or more),
Traction control is performed by both reducing the torque generated by the engine and adding braking force, and STR is 0.09.
When it becomes smaller than , an appropriate method can be adopted, such as applying the brake force to medium+FL and performing traction control only by reducing the torque generated by the engine. The conditions for discontinuing traction control include: when the accelerator is fully closed, when the vehicle speed becomes low and heavy, and when the target throttle opening based on the 15 throttle characteristics is smaller than the target throttle opening based on traction control. It is set as appropriate, such as when the

Control unit 50 further performs ABS control. In this ABS control, the wheel slip rate SAB is calculated by the following equation (2).

B -VW SAB=□... (2) B VB=Vehicle speed ■■: Wheel rotation speed The above VB is actually convenient to use the slowest rotation speed among the rotation speeds of each wheel 2 to 4. used in many ways. During braking, the hydraulic pressure control unit 30 is controlled so that 5At3 is within the range of 0.1 to 0.2. In other words, when SAB exceeds 0.2,
A state in which a large slip has occurred (a state in which wheel lock has occurred) requires BS control.

The control unit 40 basically adjusts the vehicle height, that is, adjusts the stroke between the spring height and the weight of the spring 1, based on the following equation (3).

5=So (F/k C-3/k)...
(3) S: stroke position of the piston 42 S = speed of the piston 42 F = ground load C, = constant, in addition to L, the control unit 50 controls the above-mentioned A B
When S control or traction control is being performed, the stroke of the wheel being controlled is
3) A value obtained by adding a predetermined amount ΔS′ to the value of S determined by the formula. The larger S is, the larger the stroke, ie, the vehicle height is, and therefore, by adding ΔS, the stroke is corrected to be further increased. As a result, the ground load of the wheels subject to ABS control or traction control is increased, and the slip is brought to a halt more quickly.

Flowcharts showing the control contents of the control unit 50 described in "Flowchart 11" are shown in FIGS. 2 and 3.

Note that in the following explanation, P or Q indicates a step.

First, in Pl of FIG. 2, which is the main flow, after the signals of each sensor 51 to 57 are read, the anti-skid control (ABS control), traction control, and suspension (stroke) control described above are performed (P2 ~P
4).

The details of the above P4 are as shown in FIG.

At Ql in FIG. 3, it is determined whether anti-skid control is currently being performed. When the determination in Ql is NO, it is determined in Q2 whether or not traction control is currently being performed.

When the determination in Q2 is No, it means that no wheel slip occurs. In this case, after resetting the stroke S correction flag to O in Q3, in Q4, [target stroke position i7 of the suspension (piston 42) based on equation (3) in i1? s is calculated. After this, in Q5, the control valve 47 is controlled so as to realize this target stroke S.

When the control in Q1 or Q2 is No, it is determined in Q6 whether the correction flag is set to 1 or not. If the determination in Q6 is No, it is the time to start slip control, so the supplementary IF flag is set in Q7.
Set to . After this, in Q8, the correction flag is set to 1.
It is determined whether a predetermined period of time has elapsed since the setting. This determination is made only for a predetermined period of time from the start of sleeve control.
This is for adding the stroke ΔS of the correction valve mentioned above. When the determination in Q8 is No, the target stroke S is newly set by adding ΔS of the correction valve to the value of S calculated by equation (3) in Q9, and then the process in Q5 is performed. Ru.

When the determination in Q6 is YES, the process directly proceeds to Q8 without passing through Q7. Also, if the determination in Q8 is YES, proceed directly to Q5 without going through Q9 (
(No stroke supplement iE).

Although the embodiments have been explained above, the stroke of the correction valve △
The magnitude of S may be made larger as the slippage of the heavy wheels becomes more severe. In this case, in consideration of changes in vehicle height, the magnitude of ΔS may be determined as a ratio to the value of S obtained based on equation (3). Further, as the stroke adjustment means, an air suspension that adjusts the vehicle height by adjusting air pressure in a flexible bag (diaphragm), which has already been put into practical use, can be used. Of course, the present invention detects wheel slip immediately (Equation (2) or Equation (3)) without performing ABS control or traction control, and detects when this slip exceeds a predetermined value. It can also be made to operate.

(Effects of the Invention) As is clear from the above description, the present invention effectively utilizes the stroke adjustment means interposed between the spring F heavy electric and the unsprung weight to quickly correct wheel slip. can be done.

[Brief explanation of the drawing]

FIG. 1 is an overall system diagram showing one embodiment of the present invention. FIGS. 2 and 3 are flowcharts illustrating a control example of the present invention. FIG. 4 is a block diagram showing the configuration of the present invention. 1: Cars 2-5: Wheels (unsprung weight) 41: Hydraulic cylinder (stroke adjustment means) 50: Control unit 47: Control valves 51-54: Sensor (rotation speed) 55: Sensor (stroke) 56: Sensor (load) )

Claims (1)

[Claims] (1) A stroke adjusting means for adjusting the stroke between the sprung weight and the unsprung weight, a slip detecting means for detecting wheel slip, and controlling the stroke adjusting means when wheel slip is detected. and stroke control means for increasing the ground load of the slipping wheel by increasing the stroke between the sprung weight and the unsprung weight. Device.