JP2502141B2 - Vehicle propulsion control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary of the Invention] A propulsion force control method effective for preventing slip at the time of starting a vehicle, in which the initial responsiveness of brake fluid pressure control is enhanced, and quick and appropriate slip suppression is performed. The purpose of the present invention is to provide a propulsion force control method that can monitor the slip of the driving wheels that occurs when the vehicle starts or accelerates, and when the slip is detected, control the brake fluid pressure or control the engine output and brake fluid pressure. In a propulsion force control method for a vehicle that controls the slip of the drive wheels, a continuous arbitrary three pulses among the pulses sequentially generated by the pulse generation means provided in the drive wheels are first detected. 1 pulse, 2nd pulse, 3rd pulse,
The time T ₁₂ between the first pulse and the second pulse is compared with the time T ₂₃ between the second pulse and the third pulse, and the difference ΔT = T ₁₂ −
The brake fluid pressure is pre-pressurized when T ₂₃ is positive and equal to or larger than a predetermined value.

[Industrial applications]

The present invention relates to a propulsion force control method that is effective in preventing slip when the vehicle starts.

[Conventional technology]

If the driving force is large and / or the friction coefficient of the road surface is small when the vehicle starts, the driving force may slip. If the slip is left as it is, the road surface is polished and the friction coefficient becomes smaller, so that the slip is more likely to occur and eventually the vehicle may be unable to run.

In order to prevent the slip that occurs at the time of starting or accelerating, a propulsion force control device that controls the engine output, the clutch engagement amount, and the braking force individually or in combination has been developed.

FIG. 4 shows an outline of a vehicle drive / braking control system using an automatic transmission. Reference numeral 10 is an engine, 11 is a clutch, 12 is a transmission, 13a and 13b are driving wheels, 13c and 13d are driven wheels, 14 is an accelerator pedal, 15 is an electronic control device, output control of the engine 10, clutch 11 Engagement amount control and gear ratio change control of the transmission 12 are performed. 16 is also an electronic control unit, which performs brake control. Reference numeral 21 is a brake pedal, 20 is a master cylinder, 19 is a modulator for distributing pressure oil from the hydraulic pump P, 18a and 18b are rear cut valves, and 17a to 17d are speed detectors of the wheels 13a to 13d.

The rotation speed of the driven wheels 13c and 13d is the vehicle speed (vehicle ground speed).
Can be regarded as being represented, and thus the difference between the driven wheel speed and the driving wheel speed is the slip. Slip starts /
Although it occurs at the time of acceleration, excessive slip causes the above-mentioned problem and is therefore a target for suppression. Wheel speed detector
When the electronic control unit 16 receives the outputs of 17a to 17d and determines that the drive wheel slip to be suppressed has occurred, the modulator 19
To brake the left and right drive wheels 13a, 13b. At this time, the rear cut valves 18a and 13b are closed to prevent the left and right driven wheels 13c and 13d from being braked.

In the slip suppression control, the electronic control unit 15 may control the engine output and the clutch engagement amount individually or in combination. The braking system intersects as shown in the drawing, and the left front shaft and the right rear wheel, and the right front wheel and the left rear wheel are simultaneously braked with the same pressure oil.

By the way, the brake is operated by a method such as pressing the pad against the disc with a hydraulic cylinder, but there is usually a gap between the pad and the disc. If there is a gap, it will be used to fill the gap at first even if the valve is opened to send pressure oil, and after the gap disappears, braking force will be applied to the wheels. That is, the brake operation is delayed.
Conventionally, in order to eliminate this delay, the acceleration of the drive wheels is detected as a change in the calculated wheel speed, and when this is a predetermined value or more, pre-pressurization of the brake fluid pressure is performed, and the pressure between the brake disc and the pad of the vehicle is reduced. It was filling the void.

[Problems to be Solved by the Invention]

In the conventional method, when the vehicle speed is measured, various judgments and controls are performed based on the vehicle speed, and the wheel speed is measured at a constant time cycle so that this time can be sufficiently taken.

Therefore, conventionally, it takes time to calculate the acceleration based on the vehicle speed measured last time and the vehicle speed measured this time, and it takes time to determine whether or not to apply pre-pressurization, and brake control is performed without sufficient pre-pressurization time. Since there is a gap or backlash between the brake disc and the pad of the vehicle, it takes a certain amount of time to actually brake the brake, and the initial brake fluid pressure control response is poor. .

It is an object of the present invention to provide a propulsion force control method that can improve this point, improve the initial response of the brake fluid pressure control, and quickly and appropriately suppress slip.

[Means for solving the problem]

As shown in FIG. 1, in the present invention, the slip of the drive wheels generated when the vehicle starts or accelerates is monitored, and when the slip is detected, the control of the hydraulic pressure of the brake or the control of the engine output and the brake hydraulic pressure is performed. In the propulsive force control of the vehicle for preventing the slip of the drive wheels, the first pulse and the second pulse generated by the pulse generating means provided in the drive wheels.
The time between pulses and the time between the second pulse and the third pulse are compared to detect the acceleration (), and when the acceleration is equal to or more than a predetermined value (Y), preliminary pressurization of the brake fluid pressure is performed.
If the acceleration is not higher than the predetermined value, pre-pressurization is not performed. After this control, the normal propulsion force control for slip suppression is started.

[Action]

The time between the first pulse and the second pulse emitted from the pulse generating means provided in the driving wheel, the second pulse and the third pulse.
The time between pulses is compared, the acceleration is immediately calculated, and when the acceleration is above a specified value, the brake fluid pressure is pre-pressurized, and the brake is applied when slip occurs except for the gap between the pad and the disc. Immediately after entering control, the braking force is applied to the drive wheels. This enables effective slip control.

〔Example〕

FIG. 2 shows an example of propulsive force control according to the present invention. Driving wheel / driven wheel speed detecting means (17a and 17b, 17c and 17d in FIG. 4) 17A / 17B
A pulse generator is used for the measurement of the time T ₁₂ of the first and second pulses from the driving wheel speed detection means 17A by the arithmetic circuit 16A,
The time T ₂₃ of the second to third pulses is measured and the difference ΔT = T ₁₂ −T ₂₃ between these times is obtained. Then, it is further determined whether or not preliminary pressurization is performed. The set value or闘値as T _0, the determination if [Delta] TT ₀ is YES, and preliminary pressure of the brake fluid pressure. If ΔT <T _{0, the} judgment result is
NO, no preliminary pressurization.

The determination of steps can be easily and quickly performed using a map.

The arithmetic circuit 16A and the brake fluid pressure control means 16B shown in FIG.
Corresponds to the electronic control unit 16 in FIG.

The difference ΔT between the time T ₁₂ between the first pulse and the second pulse and the time T ₂₃ between the second pulse and the third pulse is a certain value T
_When it is larger than ₀ , it means that the initial acceleration of the driving wheels is large, and thus the probability of occurrence of slip (a suppression target) is high. Therefore, at this time, pre-pressurization of the brake fluid pressure is performed to eliminate the gap or play so that the brake can be suppressed before the brakes are applied to the drive wheels immediately after the brake suppression control is started and the slip does not increase.

When the difference ΔT is smaller than the set value T ₀ , it means that the initial acceleration is not large and therefore the probability of slip occurrence is low.
At this time, pre-pressurization is not performed.

Prepressurization is performed by turning on the valve for a certain period of time and feeding a certain amount of oil into the brake pipe in advance.

During startup and acceleration (during running), the difference between the driving wheel speed and the driven wheel speed, that is, the slip is monitored, and when the difference exceeds a set value, the propulsive force control is started. Even if the preliminary pressurization of the step is performed, the propulsive force control is not always entered. When the propulsive force control is not entered, the preliminary pressurization is released after a predetermined time. When the propulsive force control is started, the brake fluid pressure is released when the control is finished, and the preliminary pressurization is also released at this time.

It is easier and quicker to use the map to determine whether or not to carry out the preliminary pressurization of the step, than to calculate the time difference ΔT and compare it with the threshold value T ₀ . FIG. 3 is a diagram for explaining the map in a graph, and a curve C is a boundary line between pre-pressurization and non-pre-pressurization. The horizontal axis of this figure is the first
The time T ₁₂ between the pulse and the second pulse, the vertical axis is the time T ₂₃ between the second pulse and the third pulse. When T ₁₂ is x and T ₂₃ is y
If y) is calculated and displayed in FIG. 2, these boundaries C
Is found. If x and y are addresses of the memory (for example, x is a high-order bit group of the address and y is a low-order bit group of the address), and the point of coordinates x and y is in the lower area of the curve C in FIG. “1” (preliminary pressurization is performed), if it is in the upper area, the stored data is “0” (preliminary pressurization is not performed)
Then, if the data is stored at the address, x (T
₁₂ ), y (T ₁₃ ), the memory can be read and a simple and quick pre-pressurization can be output.

〔The invention's effect〕

As described above, in the present invention, the time between the first pulse and the second pulse and the time between the second pulse and the third pulse emitted from the pulse generating means for measuring the wheel speed are compared,
Acceleration is detected from the difference, and if it is large, the brake fluid pressure is pre-pressurized, so that the initial responsiveness of the brake fluid pressure control can be improved, and the startability can be improved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of the principle of the present invention, FIG. 2 is an explanatory diagram of an example of propulsive force control of the present invention, FIG. 3 is an explanatory diagram of a map, and FIG. 4 is a block diagram of a drive / braking control system of a vehicle. is there. FIG. 1 shows a step of detecting the acceleration of the drive wheel at the time of starting,
Is a step of determining whether the acceleration is equal to or more than a predetermined value, and is a step of prepressurizing the brake fluid pressure.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideo Akima, Hideo Akima 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited (72) Inventor, Tomomi Okubo, 5-4-1, Higashi, Hanyu, Saitama Prefecture Central Research Institute (72) Inventor Katsuya Miyake 5-471 Higashi, Hanyu City, Saitama Prefecture Akebono Brake Industry Co., Ltd. (56) References JP 62-99250 (JP, A) JP 63- 227451 (JP, A) International publication 88-3489 (WO, A)

Claims (1)

(57) [Claims] 1. A slip of a drive wheel generated when the vehicle starts or accelerates is monitored, and when the slip is detected, control of a brake hydraulic pressure or control of an engine output and a brake hydraulic pressure is performed, and the drive wheel is controlled. In a propulsive force control method for a vehicle that suppresses slip, any three consecutive pulses are first pulse, second pulse, and third pulse among pulses that are sequentially generated by pulse generation means provided in a drive wheel. When the pulse is used, the time T ₁₂ between the first pulse and the second pulse is compared with the time T ₂₃ between the second pulse and the third pulse, and the difference ΔT = T ₁₂ −T
A propulsive force control method for a vehicle, comprising: preliminarily pressurizing the brake fluid pressure when ₂₃ is positive and equal to or larger than a predetermined value.