JPH01223064A - Slip preventing device for driving wheel - Google Patents

Abstract

PURPOSE:To improve the start accelerating property by detecting the friction coefficient between a tire and the road surface and the slip ratio during deceleration, estimating and storing the road surface condition based on the detection values, and controlling the driving torque in response to the road surface condition stored at the time of restart. CONSTITUTION:The slip ratio is detected by a slip ratio detecting means 14 based on the rotating speed of a driving wheel 11 detected by a wheel speed sensor 12 and the vehicle acceleration detected by an acceleration sensor 13, the road surface condition is calculated by a road surface condition calculating means 15 based on this slip ratio and the vehicle acceleration. This road surface condition is stored in a memory means 16 as a numerical value. At the time of restart after the vehicle is stopped, the driving force is calculated by a driving force control means 17 based on the road surface condition immediately before the stop. An actuator 18 is driven according to this calculation result, one of a throttle valve, a transmission, an ignition coil and an injector is controlled, the torque of the driving wheel is reduced, and the occurrence of a slip is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to drive wheel slip prevention control, and more particularly to a drive wheel slip prevention device suitable for preventing drive wheels from spinning when starting.

[Conventional technology]

Conventional devices are disclosed in Japanese Patent Application Laid-Open Nos. 58-38342 and 1983.
As described in No. 215434 and Japanese Unexamined Patent Publication No. 62-29461, controls and brakes that detect when the vehicle starts and the drive wheels start spinning and reduce the torque transmitted from the engine to the drive wheels. It was controlled by applying

[Problem to be solved by the invention]

In the above conventional technology, when starting on a low μ road, excessive torque is generated in the drive wheels → start of drive idle rotation → idle rotation detection → calculation → operation to reduce drive torque → reduction of drive torque → reduction of drive wheel idle rotation... It worked by following these steps.

Therefore, it is not possible to know the road surface condition until a wheel slip occurs, and the configuration is such that it is not possible to perform control in advance in accordance with the road surface condition.

An object of the present invention is to prevent even the slightest slip of the drive wheels when the vehicle starts by detecting the road surface condition immediately before the vehicle stops.

The purpose is to improve vehicle acceleration and stability.

[Means to solve the problem]

The above object can be achieved by reducing the drive torque before the drive wheels start spinning. Therefore, in the present invention, a configuration as shown in FIG. 1 is adopted.

The slip rate is detected by the slip rate detection means 14 from the rotational speed of the drive @ 11 detected by the wheel speed sensor 12 and the vehicle acceleration detected by the acceleration sensor 13. In the road surface condition calculation means 15.

The road surface condition is calculated from the slip rate and the vehicle acceleration, and the road surface condition is stored as a numerical value in the storage means 16. I memorized it when the vehicle stopped and restarted. The driving force control means 17 performs calculations based on the road surface condition immediately before stopping, and sends a signal to the driving force control actuator 18. Specifically, the driving force control actuator is any one of a throttle valve, a transmission, an ignition coil, an injector, a brake, etc., or a combination of these. The driving force control actuator reduces the torque of the driving wheels and suppresses wheel slipping.

[Effect]

Looking at the operation of a vehicle controlled by the method described above when decelerating → stopping → starting, first, while the brake is pressed and the vehicle is decelerating, the friction coefficient μ between the tires and the road surface is constantly calculated at every calculation cycle of the microcomputer. and calculate the slip rate S. Here, the friction coefficient μ between the tires and the road surface is calculated based on the vehicle acceleration α measured from the acceleration sensor. On the other hand, the slip rate S is calculated from the vehicle speed V calculated from the signal from the acceleration sensor and the signal V from the wheel speed sensor. The road surface condition is quantified from the calculated μ and S. The road surface condition here refers to whether the road surface is slippery or not. The numerical value of the road surface condition is stored and shifted each time new data is received. When the vehicle stops, the above-mentioned measurement, calculation, and storage operations are completed, and the road surface condition immediately before the vehicle stops is determined. If the road surface is determined to be slippery, the actuator is activated to quickly reduce the drive torque when starting the vehicle. in fact,
These include throttle valves, ignition coils, transmissions, injectors, brakes, etc. A vehicle controlled in this manner can improve acceleration and stability without causing even the slightest slip when starting.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 3 shows a hardware h1 diagram of the embodiment. Control unit 141
It consists of ROM, RAM, CPU, Ilo, registers, etc., and performs calculations based on the signals from sensors 2, and transmits 5. Throttle valve 6, ignition coil 7, injector 8. Control is performed to reduce the drive torque by operating the brake 9, etc., to prevent the drive wheels from spinning. Here, the sensors mainly include acceleration sensor 3. There is a wheel speed sensor 4. As an actuator, transmission 5. Throttle valve 62, ignition coil 7, injector 8. Although the five brakes 9 have been mentioned above, any other actuators may be used as long as they can reduce the driving torque6.Also, these actuators can be effective when used singly or in combination. The method of reducing the driving torque is to change the transmission 5 to a high speed gear.

The opening degree of the throttle valve 6 is reduced. Ignition coil 7
This will retard the ignition timing. In the injector 8, the amount of fuel supplied is reduced or the fuel supply is temporarily cut. In the brake 9, the brake hydraulic pressure is increased.

etc.

FIG. 4 shows the relationship between the slip rate S of the wheels during braking and the coefficient of friction μ between the tires and the road surface. As shown in the figure, the absolute value of the friction coefficient is large on dry asphalt roads, and small on snowy and frozen roads. Slip rate S and tires during deceleration
Calculating the friction coefficient μ between the road surfaces and plotting it in the figure gives a
t, a2. aa, it is possible to determine whether a slippery road surface is a non-slip road surface.

Next, the operation of the control section will be explained using the flowchart shown in FIG. 6V1, which is used to determine whether the vehicle speed V is greater than vl in step 201, is approximately 0 (hire/hour). If V > V 1, the process moves to step 202. In step 202, the coefficient of friction μ between the road surface and the tires is calculated. The actual situation is as follows.

Here, the equation of motion of the vehicle is set up as shown in equation (1), and the friction coefficient μ between the tires and the road surface is determined as shown in equation (5).

μmg=mα (1
) α μ =−・・・・・・ (2) m: Vehicle weight g: Gravitational acceleration α: Measured vehicle acceleration Next, in step 203, the brake lamp switch is turned on.
Determine whether or not. If it is ON (the brake is being pressed), it means that the brake is decelerating, so steps 204 and 205
It repeats this process, measuring, memorizing, and shifting the road surface condition until it comes to a stop.

In step 204, the road surface condition R is calculated. The actual situation is as follows.

First, calculate the vehicle speed ■. The vehicle speed V can be obtained by measuring the wheel speed Vw during steady running, but when the brakes are applied and deceleration begins, slipping occurs and the vehicle speed cannot be measured accurately. Therefore.

Using the wheel speed when the brake SW is turned ON as an initial value, integration is performed every calculation cycle as shown in equation (1) based on the output of the acceleration sensor.

Vn =Vn-t+a・At-(3
) V, : Calculate the rate S. The slip rate S can be expressed as in equation (4).

■V: Vehicle speed 7w determined by equation (1): Calculate the reference friction coefficient A for determining the road surface condition (high μ road or low μ road) based on the axle speed measured by the wheel speed sensor. The reference friction coefficient A is determined as a function of the slip ratio S as shown by the dashed line in FIG. Actually R.O.
I keep it inside M as a table.

A=f (S) ・Old...
(5) Using μ and A obtained so far, calculate the road surface condition R (
6) Calculate as shown in formula. If the road surface condition R is greater than 1, it is determined that the road surface is not slippery, and if it is less than 1, it is determined that the road surface is slippery.

R: Old... (6) After calculating the road surface condition R at the current time in step 204,
At step 205, R is stored in memory.

Shift n pieces of data one by one. In this way,
In steps 201 to 205, vehicle speed V>
While the brake pedal is depressed, R is calculated and the memory/data shift is repeated.

The above is an operation during deceleration, but if it is determined in step 201 that the vehicle has stopped, the process moves to step 208.

In step 208, road surface condition R1 (i-th data)
If it is smaller than 1, it is regarded as a low μ road, and control is performed to reduce the driving force torque. In this embodiment, steps 209~
Control was performed to apply brakes to the driving wheels as in 212. If it is determined in step 208 that \RI≧1, that is, the road is high μ, brake control is not performed during the first start.

If the road surface condition immediately before the stop is determined to be a low μ road, it is further divided into several stages (two stages in this embodiment) in step 209. In step 210, the target value of the brake torque Ta is set to a, and in step 211, the target value of the brake torque is set to b. In step 212, a signal for driving the brake hydraulic circuit is issued. In this way, braking torque is applied to the wheels depending on the road surface condition, and the driving force is reduced during the first start to prevent the axle from spinning. After the above-mentioned control is performed and the vehicle finishes spinning the drive wheels or starting, the process moves from steps 201, 202, and 203 to step 206. When entering step 206, the vehicle body is in a running state, so the brake torque is controlled in real time. First, engine torque TE is estimated. This is because engine torque is essential for calculating brake torque. The engine torque can be estimated from the engine speed N and the air IQ flowing into the engine. Figure 5 shows the engine torque Te at full throttle.
FIG. 6 shows the efficiency η depending on the amount of air flowing into the engine, and the engine torque can be expressed as in equation (7).

TE = Te Xη ・・・・・・ (
7) Next, the driving torque at the driving wheels is expressed as in equation (8).

T"wheem = TE X G X -...-(
8) In equation (8), G is the total reduction ratio of 1-transmission and differential gear, and the value multiplied by - is the torque distribution by the differential gear.

Next, in step 207, a target value Ta of brake torque is calculated. If we draw up an equation of motion focusing on the drive wheels of a running vehicle, it can be expressed as equation (9).

w ■・:= Twheem −TO−μmW−R−(9)
t I: Moment of inertia of the wheel W: Rotation angular velocity of the wheel W: Load applied to the axle R: If the radius W of the wheel has a target value, the brake torque T.

The target value of is given as in equation (10).

t (10) After setting the brake torque target value TB during running in this way, the process moves to step 212, and a drive signal for the brake hydraulic circuit is output.

Figure 7 shows the control effect when performing the above series of operations. Figure 7 shows the brake lamp SW, throttle angle, and drive wheel slip when decelerating → stopping → starting on a low μ road. This shows the rate and brake oil pressure. To explain step by step, there is a vehicle that is decelerating only by engine braking, and the brake is stepped on at time a. Then, the calculation of the road surface condition R and the vehicle speed V is repeatedly performed, and the process ends at point b when the vehicle speed becomes around O. Since it is determined that the road is a low μ road based on the road surface condition RL, a predetermined amount of brake torque is applied before starting the vehicle. Next, when the throttle is opened from time C to start the vehicle, the present invention applies brake torque in advance, so that no extra slip of the drive wheels occurs. In the conventional example, the vehicle starts without applying brake torque, so
Immediately, the drive wheels begin to spin excessively, and this is detected at time d.

Furthermore, a signal is issued to increase the brake hydraulic pressure, and the actuator receives this signal and completes the pressure increase, and the drive wheels are prevented from spinning at time e.

As mentioned above, the effects of the present invention have been described in comparison with the conventional example, but the effects of the present invention are not limited to the case where the drive torque is reduced by brake control, but also when reducing the drive torque by controlling the throttle valve, transmission control, etc. This can also be expected when timing control, fuel injection control, etc. are used, and in either case, it is possible to improve acceleration and stability when starting on a low μ road.

〔Effect of the invention〕

According to the present invention, control is performed to reduce the excessive torque of the drive wheels at the time of starting according to the road surface condition immediately before the vehicle stops, so that acceleration is achieved without causing even the slightest slip when starting on a low μ road. , which is effective in improving stability.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a flowchart showing the operation of the control section, FIG. 3 is a hardware configuration diagram of an embodiment of the present invention, and FIG. 4 is a slip ratio S.
Fig. 5 is a diagram showing a table of engine torque, Fig. 6 is a diagram showing engine torque efficiency, and Fig. 7 shows the effects of the present invention. It is a diagram. DESCRIPTION OF SYMBOLS 1... Control part, 2... Sensors, 3... Acceleration sensor, 4... Wheel speed sensor, 5... Transmission, 6... Throttle valve, 7... Ignition coil, 8
...Injector, 9...Brake. Fig. 1 Fig. 2 Fig. 3 Fig. 4

Claims (1)

[Claims] 1. A driving wheel slip prevention device comprising various sensors for detecting vehicle conditions and means for reducing the torque transmitted from the engine to the driving wheels based on the signals thereof. means for detecting the friction coefficient μ between the two, means for detecting the slip rate S during deceleration, means for estimating the road surface condition by comparing the obtained μ, S with a reference friction coefficient pattern, and a means for estimating the road surface condition. A drive wheel slip prevention device characterized in that it is provided with a memorizing means and a means for reducing the drive torque in accordance with the memorized road surface condition when restarting. 2. In the means for detecting the friction coefficient μ between the tire and the road surface as described in item 1, the driving wheel slip prevention device is characterized in that μ is calculated based on an output signal of an acceleration sensor. 3. The means for detecting the slip rate S described in item 1 is characterized in that the slip rate S is calculated based on the vehicle speed V obtained from the output signal of the acceleration sensor and the wheel speed Vw measured by the wheel speed sensor. Drive wheel slip prevention device. 4. A driving wheel slip prevention device characterized in that the means for reducing the driving torque described in item 1 applies a driving wheel brake. 5. A driving wheel slip prevention device characterized in that the means for reducing the driving torque described in item 1 closes a throttle valve. 6. In the means for reducing the drive torque as described in item 1, the driving wheel slip prevention device is characterized in that the gear is shifted to a high speed side by a transmission. 7. A drive wheel slip prevention device characterized by retarding ignition timing in the means for reducing drive torque as described in item 1. 8. A driving wheel slip prevention device characterized in that the means for reducing the driving torque described in item 1 reduces the amount of fuel supplied.