JPH0367762A - Acceleration slip control device - Google Patents

Abstract

PURPOSE:To correctly determine whether the start of a vehicle is easy or difficult by determining that the start of the vehicle is difficult if the speed of the vehicle body is less than a predetermined threshold at the start of a pressure increasing mode of a wheel cylinder for actuating the brake of a driving wheel. CONSTITUTION:A fluid pressure control device A controls the fluid pressure of a wheel cylinder for actuating the brake of a driving wheel, after patterns which are different according to whether the start of a vehicle is easy or difficult. In the above constitution, the speed of the vehicle body is detected by means B. The starting period of a pressure increasing mode to be carried out after the tendency of slip to decrease first appears in a driving wheel is detected by means C. The speed of the vehicle body is compared to a predetermined threshold at the start of the pressure increasing mode and, when the speed of the vehicle body is less than the threshold, such diagnosis is made by means D that the start of the vehicle is difficult. Thus the period at which the speed of the vehicle body is detected is properly selected so as to correctly determine whether the start of the vehicle is easy or difficult.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an acceleration slip control device of a type that changes a control pattern of wheel cylinder hydraulic pressure depending on the difficulty of starting a vehicle, and particularly relates to an acceleration slip control device that accurately determines the difficulty of starting a vehicle. It is related to the technology to

[Conventional technology]

The above-mentioned type of acceleration slip control device generally controls the hydraulic pressure of the wheel cylinder that operates the brakes of the drive wheels using different control patterns depending on whether the vehicle is easy to start and when it is difficult to start. The vehicle is configured to include a hydraulic pressure control device that controls the hydraulic pressure of the wheel cylinder to a level that keeps the slip of the driving wheels within an appropriate range when the vehicle accelerates.

The control pattern is a pressure increase mode (e.g. rapid pressure mode, il pressure increase mode) to increase the wheel cylinder hydraulic pressure.
and decompression mode (e.g. rapid decompression mode,
In some cases, the mode is configured in combination with a gradual pressure reduction mode), and in other cases, it is configured in combination with a pressure increase mode and a pressure reduction mode, and a pressure holding mode for keeping the wheel cylinder hydraulic pressure constant. In addition, the control pattern suitable for when starting is difficult is said to be closer to the pressure increasing side compared to the control pattern suitable when starting is easy, and as a result, even when starting is difficult, the slip of the drive wheels is suppressed to the same extent as when starting is easy. Ru.

The applicant previously developed one of this type of acceleration slip control device. This is the device described in Japanese Patent Laid-open No. 63-219465. This device includes a vehicle speed detecting means for detecting the vehicle speed, a timing detecting means for detecting the time when the speed of the driving wheels starts to decrease for the first time due to the operation of the hydraulic pressure control device, and a starting difficulty determining means. In addition, the difficult-to-start determination means compares the detection result of the vehicle body speed detection means when the timing detection means detects the start of decrease with a predetermined threshold value, and determines whether the detection result is a threshold value. If it is below this value, it is determined that it is difficult to start.

In addition, in this type of acceleration slip control device, when starting the vehicle on an uphill road, it is difficult to start, and when starting the vehicle on a flat road or a downhill road (hereinafter collectively referred to as a flat road), it is easy to start. Generally selected.

Furthermore, even if the road on which the vehicle is about to start is flat, the coefficient of friction of the road surface (hereinafter simply referred to as road surface μ) is 0. For roads with extremely low μ of less than 2, the difficult-to-start control pattern is suitable, as in the case of uphill roads. If the road on which the vehicle is about to start is flat, the flat road may be a snow-compacted road (a snow road where the snow that has accumulated on the road surface is compacted and hardened) or a rough ice-cover road (a snow road where the snow that has accumulated on the road surface is compressed and hardened) The road surface μ is 0.2 to 0, such as icy roads with protrusions.
．． When the road surface μ is 0.4, such as a road with a low μ of about 4, or a gravel road, etc. If the road is medium or high than 4, the easy-to-start # control pattern is suitable, but if the road is very low, the difficult-to-start control pattern is executed instead of the easy-to-start control pattern. It is better.

[Problem to be solved by the invention]

Subsequent research by the applicant revealed that there is room for improvement in the conventional device. When the conventional device performs acceleration slip control when starting a vehicle on a flat road, as is clear from the experimental results shown in Fig. 9,
If the road on which the vehicle is about to start is a flat, low-μ road (hereinafter referred to as a low-μ flat road), for example, if the drive torque applied to the drive wheels when starting the vehicle is excessive, it may cause the vehicle to start easily. It has been found that there is a problem in that the vehicle is incorrectly determined to be in a situation where it is difficult to start. If such difficult-to-start control is performed, an undesirable situation will occur in which the acceleration performance of the vehicle is insufficient.

Note that since the judgment by the difficult-to-start determination means is made during the acceleration slip control, the vehicle speed used in the judgment is not necessarily the one obtained by the easy-to-start control; It may be obtained through control. However, FIG. 9 representatively shows the experimental results corresponding to the determination results based on the vehicle speed obtained in the former case.

The present invention has been made with the object of solving the above-mentioned problems by selecting an appropriate timing for detecting vehicle body speed for control when starting is difficult.

[Means to solve the problem]

The gist of the present invention is, as shown in FIG. 1, in an acceleration slip control device comprising the hydraulic pressure control device, a vehicle speed detection means, a two-timing detection means, and a difficult-to-start determination means. The time when the pressure increase mode is started is detected for the first time after the slip reduction tendency occurs in the drive wheels for the first time due to the operation of the pressure control device. The detection result of the vehicle body speed detection means at the time of detection is compared with a predetermined threshold value, and if the detection result is less than the threshold value, it is determined that it is difficult to start. .

[Effect]

In the device of the present invention, the vehicle body speed for determining the difficulty of starting is set at a later time than in the conventional device, that is, the start of the pressure increase mode is performed for the first time after a low N tendency of slip occurs in the drive wheels due to acceleration slip control. The vehicle speed at 7 o'clock is used.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An acceleration slip control device according to an embodiment of the present invention will be described in detail below with reference to the drawings. This acceleration slip control device is installed on a vehicle in which the front wheels are idle wheels and the rear wheels are drive wheels, and it also includes means for reducing the output torque of the engine and hydraulic pressure to suppress the rotation of the drive wheels. This is used in combination with a brake device.

In FIG. 2, 10 is an engine, and its intake manifold 12 is provided with a main throttle valve 14 and a sub-throttle valve 16 in series, and the output torque of the engine 10 is adjusted by opening and closing these valves. It looks like this. The main throttle valve 14 is opened and closed by operating an accelerator pedal 18, and the depression of the accelerator pedal 18 is detected by an accelerator sensor 20. The sub-throttle valve 16 is opened and closed by a sub-throttle control motor 22, and its opening degree is detected by a sub-throttle sensor 24.

At the bottom of Figure 2, left and right front wheels 26.28 and left and right rear wheels 3
0.32 is shown. Rear wheels 30 and 32 are connected to the engine 10 through a power transmission mechanism (not shown) and are driven by the engine 10. Each wheel 26 to 32 is provided with a hydraulic brake 34 to 40, respectively, and these hydraulic brakes are connected to the main mask cylinder 4.
It is operated by brake fluid supplied from 2.

The hydraulic brakes 34 to 40 each include a wheel cylinder, and the brake fluid pressure transmitted to each wheel cylinder causes the corresponding hydraulic brake 34 to 40 to be
is activated.

The main mask cylinder 42 generates equal height hydraulic pressure in two independent pressurizing chambers when the brake pedal 44 is depressed, and the hydraulic pressure generated in one pressurizing chamber is passed through a liquid passage 46. The hydraulic pressure generated in the other pressurizing chamber is transmitted to the hydraulic brakes 34, 36 of the front wheels, and is transmitted to the hydraulic brakes 38, 40 of the rear wheels via the liquid passage 48.

A change valve 50 connected to an auxiliary mask cylinder 52 is provided in the middle of the liquid passage 48 . The change valve 50 normally shuts off the hydraulic brake 38.40 from the sub-mask cylinder 52 and communicates it with the main mask cylinder 42, but when brake control belonging to acceleration slip control is performed, the change valve 50 disconnects the hydraulic brake 38.40 from the sub-mask cylinder 52. This is a switching valve that shuts off the main mask cylinder 42 and communicates with the sub mask cylinder 52.

The sub-mask cylinder 52 is operated by hydraulic fluid supplied from the accumulator 54 via the electromagnetic directional control valve 56 and the electromagnetic flow control valve 58 .

The electromagnetic directional switching valve 56 selectively communicates the accumulator 54 and the reservoir 61 with the sub-mask cylinder 52 under the control of the control device 60, so that brake fluid is supplied from the sub-mask cylinder 52 to the hydraulic brake 38.40. It increases or decreases the pressure. Further, the electromagnetic flow control valve 58 switches the flow rate into two stages, large and small, by changing the duty ratio of the solenoid excitation current supplied from the control device 60, and increases or decreases the pressure of the sub-mask cylinder 52 in two stages, slow and fast. The fluid pressure of the sub mask cylinder 52 can be kept constant by continuous excitation.

The hydraulic fluid pumped up by the pump 62 from the reservoir 61 is accumulated in the accumulator 54.
The hydraulic pressure of the accumulator 54 is detected by a hydraulic pressure sensor 64, and based on the detection result, the control device 60
Starting and stopping of a pump motor 65 that drives the pump 62 is controlled, so that the accumulator 54 always stores hydraulic fluid within a constant hydraulic pressure range.

The rotational speeds of the left and right front wheels 26.28 are detected by left and right front wheel speed sensors 66.68, respectively, and the rotational speeds of the left and right rear wheels 30.32 are detected by a rear wheel speed sensor 70. The rear wheel speed sensor 70 detects the rotational speed of the rear wheel 30.32 based on the rotational speed of the output shaft of the transmission provided between the engine 10 and the rear wheel 30.32. These speed sensors 66, 68, 70 are connected to the control device 60.

As shown in FIG. 3, the control device 60 includes a CPU 72, an RO
M74. It is mainly a computer equipped with a RAM 76, a bus 78, etc., and this computer has an input section 8.
The respective sensors are connected via the output section 82
via the auxiliary throttle control motor 22. Electromagnetic directional valve 56. Electromagnetic flow control valve 58 and pump motor 65
is connected.

The ROM 74 stores various control programs including a brake control routine shown in the flowchart of FIG. 4, a difficult start detection routine shown in the flowchart of FIG. 5, and an easy start detection routine shown in FIG. A pressure increase/decrease mode table for use when starting is difficult and a pressure increase/decrease mode table for when starting is difficult shown in FIG. 7 are stored.

An example of drive wheel slip control by the acceleration slip control device configured as described above is shown in FIG. If it is increased as shown in the center of the figure, the vehicle speed vv (the average value of the speed of the front wheels 26.28, hereinafter abbreviated as vehicle speed ■) will increase as shown in the center of the figure. However, in that case, the first reference speed vI and the second reference speed V! are the vehicle speeds V
, is determined to be larger by a predetermined value. and,
The driving wheel speed, that is, the rear wheel speed vr is the first reference speed vI
If the opening degree θ1 of the sub-throttle valve 16 is exceeded,
As a result, the output of the engine 10 is reduced, and the rear wheel speed V is controlled to be approximately equal to the first reference speed vl. However, when the rear wheel speed v2 further increases and exceeds the second reference speed ■, the brake fluid pressure P is transmitted to the hydraulic brake 38.40, so that the left and right rear wheels 30.32 Rotation is suppressed. By doing so, it is possible to suppress the rotation of the drive wheels while eliminating wasted energy and avoiding shortening of the life of the brake friction material as much as possible.

As is clear from FIG. 8, the sub-throttle valve 16 is rapidly rotated in the closing direction at the same time that the vehicle speed (2) exceeds the first reference speed (V), and its opening degree θ is changed to the initial target opening. After reaching the degree θ (□〉), the rear wheel speed vP is controlled by feedback control so as to approach the first reference speed ■1, but since this control is not directly related to the present invention, the details will be explained below. A detailed explanation will be omitted, and the control of the hydraulic brake device according to the present invention, which performs different controls depending on whether it is easy to start or when it is difficult to start, will be explained in detail below based on the flowcharts of FIGS. 4 and 5.

While the key switch of the vehicle is in the ON state, a determination routine (not shown) is executed to determine that engine output control, which belongs to acceleration slip control, needs to be performed because the rear wheel speed ■ has reached the first reference speed ■. If the determination is made, the computer executes the brake control routine shown in FIG. 4 at regular intervals. First, in step 3100 (hereinafter simply referred to as 5100, the same applies to other steps), a flag FII (
Since eFl, which is used to determine whether or not F (hereinafter simply referred to as F) is O, is set to 0 in the initial settings that are made at the same time as the computer is turned on, the result of the determination is YES.
Then, 3110 is executed.

At 3110, it is determined whether the brake control start condition is satisfied. Specifically, the vehicle speed Vv is calculated as the average value of the speeds of the left and right front wheels 26.28 which are idle wheels,
The speed vl and acceleration G of the rear wheels 30.32, which are the driving wheels, are calculated based on the output signal of the rear wheel speed sensor 70,
After a predetermined constant value is added to the vehicle speed (2) to calculate the second reference speed Vo, it is determined whether the rear wheel speed vr exceeds the second reference speed v2.

When the vehicle initially starts, the rear wheel speed V is smaller than the second reference speed V2, so the determination result is No, and the solenoid of the electromagnetic directional control valve 56 and the solenoid of the electromagnetic flow control valve 58 are kept in a demagnetized state, and the sub The mask cylinder 52 is the reservoir 6
1, and the hydraulic brakes 38, 40 are not activated.

While the above execution is repeated, as shown in FIG. 8, the rear wheel speed v,, comes to exceed the second reference speed Vz, and if the brake control start condition is satisfied, the determination result of 3110 becomes YES, After F is set to 1 in 3120, in 5130, while the solenoid of the electromagnetic directional control valve 56 is energized, an excitation current with a low duty ratio (for example, O) is supplied to the solenoid of the electromagnetic flow control valve 58, Initial control is performed in which the sub-mask cylinder 52 is communicated with the accumulator 54, and the brake fluid pressure P of the hydraulic brakes 38 and 40 is rapidly increased. In this initial control, the rear wheel acceleration V is changed from a positive value to OG to -0.5.
It continues until it decreases to G. The rapid pressure mode is executed until the rear wheels 30.32 reliably exhibit a tendency to reduce slip, and thereby the slip of the rear wheels 30.32 is quickly suppressed at the beginning of the acceleration slip control. Hereinafter, the rapid pressure increase mode in the initial control will be referred to as a simple pressure increase mode (represented by FFU in the figure). The computer executes the difficult-to-start detection routine shown in FIG. 5 only once when the initial control is started, and this process will be described in detail later.

If the initial control is completed in 3130, 5140
, a flag F (hereinafter simply referred to as F
) is 0 or not. F3 is Fl
Similarly to 1. It is set to 0 in the initial setting performed at the same time as the computer is powered on, and thereafter it is changed to 1 or returned to 0 by executing the difficult-to-start detection routine shown in FIG. However, since it is now just after the end of the initial control and the execution of the difficult-to-start detection routine has not yet finished, the value of F remains 0, the judgment result is YES, and at 3150 An easy-to-start control is performed to control the brake fluid pressure P based on the standard. Specifically, vehicle speed vv, rear wheel speed v1. Rear wheel acceleration G1. , the first and second reference speeds V, , V, etc. are calculated, and based on the calculation results, the pressure increase/decrease mode is determined according to the pressure increase/decrease mode table for easy start shown in FIG. , the brake fluid pressure P is controlled in the pressure increase/decrease mode.

If the easy start control is executed for a certain period of time in 3150, it is determined in 3190 whether it is necessary to terminate the brake control, that is, whether the brake control termination condition is satisfied. For example, if the accelerator pedal 18 is released and the opening degree θ of the main throttle valve 14 becomes smaller than the opening degree θ of the auxiliary throttle valve 16, it is determined that the brake control termination condition is satisfied. Ru. Assuming that the brake control termination condition is not currently met, the determination result of 5190 is NO, and 3
The execution of step 200 is bypassed and the current execution of the brake control routine ends.

When the execution of the brake control routine is restarted, since F is currently 1 and not O, the current determination result of 5100 is NO, and the actual 1 steps of 5IIO to 3130 are bypassed. As a result, once the brake control start condition is satisfied, the success or failure of the brake control start condition is not determined unless the brake wIllI end condition is satisfied, and the initial control is performed only once immediately after the brake control start condition is satisfied. will be held.

After that, if steps 3140, 3150, 3190 and 5100 are repeated many times, the brake fluid pressure P7 is increased or decreased according to the slip of the rear wheel 30.32, and the multiple pressure increase/decrease modes executed at that time are In this embodiment, each of which is suitable for multiple values of rear wheel speed V, rear wheel acceleration G1, and vehicle speed vv, the control pattern is a combination of the plurality of pressure increase/decrease modes.

In addition, in the rapid pressure reduction mode, which is the pressure increase/decrease mode, the solenoid of the electromagnetic directional control valve 56 is demagnetized and the solenoid of the electromagnetic flow control valve 58 is set at a low duty ratio (for example, O).
The slow pressure reduction mode is realized by supplying an excitation current of This is achieved by providing a high duty ratio excitation iit current.

In the slow pressure increase mode, while exciting the solenoid of the electromagnetic directional switching valve 56, an excitation current with a high duty ratio is supplied to the solenoid of the electromagnetic flow control valve 58, and the sub mask cylinder 52
The pressure holding mode is achieved by keeping the solenoid of the electromagnetic flow control valve 58 in communication with the reservoir 6.
This is achieved by cutting off both the Akiemulator 54 and the Akiemulator 54.

Above, we have explained the case where F, is O, but next, F, is 1
A case will be explained below.

After steps 5100-3130 are sequentially executed in the same way as when F, fJ<0, if it is determined in 5140 whether or not F is 0, then based on the above assumption, the current determination result in 8140 will be No. , 3160, the vehicle speed vv is 4b
/h or more is determined. Assuming that the vehicle speed vv is currently smaller than 4) aa/h, the determination result at 3160 is No, and the difficult-to-start control is performed at 3180. Specifically, similarly to the case of 3150, vehicle speed v1 rear wheel speed ■2. Rear wheel acceleration G, first and second reference speeds V,,V! Based on the calculation results, a pressure increase/decrease mode is determined according to the pressure increase/decrease mode table for when starting is difficult, and the brake fluid pressure P is controlled in the pressure increase/decrease mode. be done.

The table in FIG. 7 is closer to the pressure reduction side than the table in FIG. 6. Thereafter, it is determined in 3190 whether the brake control condition is satisfied, and if it is assumed that this is not the case, the current execution of the brake control routine ends.

After that, if steps 5IO0, 5140, 5160, 5180, and 5I90 are repeated many times, the brake fluid pressure P is controlled with a control pattern closer to the pressure increase side in the easy-to-start control, and the brake fluid pressure P is controlled during difficult-to-start and easy-to-start. The brake fluid pressure P is controlled using different control patterns depending on the time.

If the vehicle accelerates to the point where it is no longer necessary to carry out difficult-to-start control while the difficult-to-start control continues, the system shifts to easy-to-start control even if the road is on a boarding road. In the example, the condition for this is vehicle speed■9
4b/h or more, and the above-mentioned step 3160 determines whether or not this condition is met. 5160
If the determination result is YES, F! at 5170! After is returned to 0, easy-to-start control is performed at 5150.

If the brake control termination condition is satisfied while the execution of the brake control routine described above is repeated, 519
The determination result of 0 becomes YES, and after Fm is returned to 0 at 5200, the current execution of the brake control routine ends.

Next, how to detect when starting is difficult will be explained based on the flowchart of FIG.

First, at 5300, it is determined whether the current pressure increase/decrease mode in brake control is one of the pressure holding mode, IIM pressure mode, and rapid pressure decrease mode (represented by H, SD, or FD in the figure).

Assuming that the current simple pressure increase mode has started and the simple pressure increase mode has not ended, the determination result at 5300 is No, and at 3310 the vehicle speed Vv is 4h/h.
It is determined whether or not the value is greater than or equal to the value. Currently, vehicle speed vv is 4)
If it is assumed that the speed does not reach cm/h, the result of the determination is No, and the process returns to 3300.

While the execution of 5300 and 3310 is repeated,
If the mode shifts to one of the pressure holding mode, slow pressure reduction mode, and rapid pressure reduction mode, the determination result in step 3300 becomes YES and step 3320 is executed, but before the shift, the vehicle speed ■ becomes 4b.
/h or more, F is returned to O in 3360.

5320, the current pressure increase/decrease mode is either rapid pressure increase mode or slow pressure increase mode (FU or SU in the figure).
) is determined. Assuming that it is currently in pressure holding mode, slow pressure reduction mode, or rapid pressure reduction mode, the determination result of 5320 is No, and 533
At 0, it is determined whether the vehicle speed ■ is equal to or higher than 4 kgt/h.

While the execution of 3320 and 5330 is repeated,
If the mode is shifted to either the rapid pressure increase mode or the slow pressure increase mode, the determination result in 5320 becomes YES and step 3340 is executed, but if the vehicle speed vv becomes 4 km/h or more before the shift, At 5360, Fs is returned to zero.

3340, the vehicle speed vv at that time is 1.5b/
It is determined whether or not it is less than or equal to h. If it is easy to start, the vehicle speed vv is 1.5 km/
Normally, the speed exceeds 1.5 km/h, but if it is difficult to start, the speed will not exceed 1.5 km/h, so the Y of 5320
Depending on whether the vehicle speed vv at the time of ES determination exceeds 1.5 km/h, it is possible to detect whether it is difficult to start. As shown in FIG. 8, conventionally, the vehicle speed is at the time when the rear wheels 30.32 first start to show a tendency to reduce slip due to acceleration slip control, that is, for example, at the end of the simple pressure increase mode.

Difficulty starting was detected based on whether or not the speed exceeded 1.5 km/h, but at the end of the simple pressure increase mode, if the road on which the vehicle is trying to start is a flat road with a low μ, the accelerator pedal If 18 is strongly depressed, the vehicle speed vv may not exceed 1.51 as/h, and it may be erroneously detected that the vehicle is in a state where it is difficult to start. However, in this embodiment, the vehicle speed vv at the start of the rapid pressure increase mode or the slow pressure increase mode, which is performed for the first time after the simple pressure increase mode, which is later than the end of the simple pressure increase mode, is 1.5 km. Since starting difficulty is detected based on whether or not the vehicle speed exceeds 1.51a1/h, even if the driving road is a low μ flat road, the vehicle speed ■1 will more reliably exceed 1.51a1/h, indicating that it is easy to start. Able to accurately detect facts.

Furthermore, while the road on which the vehicle is about to start is flat,
In the case of a high μ road, the vehicle will continue to accelerate even if the pressure holding mode, rapid pressure reduction mode, or slow pressure reduction mode is executed after the simple pressure increase mode ends. Rear wheel 30.32 by running mode
In many cases, the slip does not increase that much. In this case, since the rapid pressure increase mode does not change to the slow pressure increase mode, it is detected that starting is difficult based on the vehicle speed vv, that is, the 5340
is not executed, and therefore, when the vehicle speed vv exceeds 4 tan/h, F is set to O.

The aforementioned FIG. 9 shows experimental results when acceleration slip control is performed by the conventional device when the vehicle starts on a flat road, as well as experimental results when acceleration slip control is performed by the device of this embodiment. As is clear from this figure, in the case of this embodiment, when the vehicle starts on a low μ flat road, it is determined that it is easy to start, and
The range in which the range of road surface μ for which it is determined that starting is easy and the range of road surface μ for which starting is determined to be difficult is narrower than in the conventional example. In this way, in this embodiment, the accuracy of detecting difficult-to-start conditions is improved, and inappropriate starting-difficult-to-start control is suppressed from being performed when the vehicle starts on a flat road with a low μ.

If the determination result at 3340 in FIG. 5 is YES, Fs is set to l at 5350, but N
If o, then F at 3360.

is returned to O.

It should be noted that in this embodiment, the vehicle speed ■ at the start of the rapid pressure increase mode or slow pressure increase mode is 1.5)
In addition to the case where the vehicle speed exceeds AS/h, the vehicle speed increases to 4.
tan/h or more, or if the vehicle speed vv becomes 4b/h or more while waiting for the start of rapid pressure increase mode or slow pressure increase mode, by setting F to O, unnecessary Difficult start control is now prevented.

Figures 10 and 11 show the case where the difficult-to-start control is performed when starting the vehicle at full acceleration on a flat and rough ice slope (road surface μ of 0.2 to 0.3), and the case where the vehicle starts. Fl value and brake fluid pressure P when easy control is performed,
, rear wheel speed ■, vehicle speed vv, and subthrottle opening θ.As is clear from this figure, the vehicle is in good condition in both cases from changes in rear wheel speed v, . However, when the difficult-to-start control is performed, the brake fluid pressure P fluctuates more than when the easy-to-start control is performed.

is controlled to the pressure increasing side. Therefore, if the difficult-to-start control is performed when starting a vehicle on a flat road with low μ, the acceleration of the vehicle is insufficient, and the brake fluid pressure P,
However, in this embodiment, when starting the vehicle on a flat road with a low μ, the easy starting control is used instead of the difficult starting control. Therefore, problems such as insufficient vehicle acceleration and deterioration of driving feeling do not occur.

Furthermore, since the difficult-to-start detection is performed during the execution of acceleration slip control, control that does not match the detection result before F is set, that is, in the non-detection stage before the difficult-to-start detection results are obtained. There are cases in which the easy-to-start control is executed even though it is difficult to start, and there are cases in which the difficult-to-start control is executed even though it is easy to start. In the former case, since the brake fluid pressure Pr is controlled from its original state to the pressure reduction side in the undetected stage, there is a possibility that the slip of the rear wheels 30, 32 will increase and the acceleration slip control will not be able to be performed normally. There is. In addition, in the latter case, since the brake fluid pressure P is controlled from its original state to the pressure increasing side in the undetected stage,
There is a possibility that the slip of the rear wheels 30, 32 is suppressed to a small level, and the acceleration performance of the vehicle is reduced.

However, in this embodiment, the period during which the non-matching control pattern is executed until the detection of difficult start is from the end of the simple pressure increase mode until the start of the rapid pressure increase mode or the slow pressure increase mode. Actually, for example, 100~
Since it is 200Ils, except for special cases mentioned below,
Even if the easy-to-start control is executed when it is difficult to start, the slip will not become excessive, and even if the difficult-to-start control is executed when it is easy to start, the slip will not be suppressed too much. In either case, there is no problem with the smooth start of the vehicle.

A special case is, for example, a case where the slope of the climbing road is close to the maximum value at which the vehicle can climb. In this case, if the easy-to-start control is performed in the non-detection stage, the vehicle may become unable to start. For example, when originally pressure holding mode should be executed, slow depressurization mode or! , the pressure mode is executed, the slip of the rear wheels 30, 32 is not well suppressed, and the slip causes the road surface μ to become even lower, which may cause the vehicle to start moving backwards.

However, in this case, the driver releases the accelerator pedal 18 and depresses the brake pedal 44, thereby ending the inappropriate acceleration slip. In this way, by the time the accelerator pedal 18 is released, the vehicle speed vv normally reaches 1.5 at 3340 in FIG.
km/h or less, F at 5350
, is set to 1. In this embodiment, the value of F cannot be reset to 0 even after the current acceleration slip control ends unless the power of the computer is turned off. Therefore, the next acceleration slip control starts from the value of Fl. is 1
As a result, in the next acceleration slip control when starting on the same metal plate road, the difficult-to-start control is executed from the beginning of the control. As a result, it is unlikely that the car will be unable to start again on the same pitched road. In this embodiment, the final value of F3 in the previous acceleration slip control is set as the initial value of F in the next acceleration slip control, so that This prevents the vehicle from becoming unable to start.

Additionally, the first acceleration slip that occurs after the vehicle's key switch is turned on is normally when the vehicle starts easily.In this embodiment, due to such circumstances, the computer of The initial value, which is the value immediately after the power is turned on, is set to O, which indicates when starting is easy.

As is clear from the above explanation, in this example,
The front wheel speed sensor 66.68 and a section 3340 in FIG. The part that executes constitutes the timing detection means. Also, the part that compares the vehicle speed vv of 3340 and 1.5 km/h of the computer, 5310, 5330
．． The part that executes each of 3350 and 3360 constitutes a control stage for when starting is difficult, and 1.5101
/h is the threshold for determination. Also, change pulp 50. Sub-mask cylinder 52. Accumulator 54. Electromagnetic directional valve 56. Electromagnetic flow control valve 58. Reservoir 61. Speed sensor 66, 68, 70. A hydraulic control device is constituted by a portion of the computer that executes the control program shown in FIG. 4, and the like. Front wheel speed sensor 66
．． Reference numeral 68 is shared by the vehicle speed detection means and the hydraulic pressure control device.

Although one embodiment of the present invention has been described above in detail based on the drawings, the present invention can be implemented in other embodiments.

For example, in this embodiment, the pressure increase/decrease mode table for when starting is difficult is set closer to the pressure increase side compared to the pressure increase/decrease mode table for easy to start, and the first and second reference speeds V, V is common to both tables, but the pressure increase/decrease mode table for when starting is difficult is set closer to the pressure increase side as in the case above, and the first and second reference speeds V , , V in the pressure increase/decrease mode table for difficult to start is smaller than that in the pressure increase/decrease mode table for easy to start, or and at least one of the first and second reference speeds V, , V is smaller in the pressure increase/decrease mode table for when starting is difficult than in the pressure increase/decrease mode table for easy to start. You can do it like this. In either case, the control pattern of the brake fluid pressure P during the difficult-to-start control can be made closer to the pressure increase side than the control pattern during the easy-to-start control.

In addition, the hydraulic ram device shown in FIG. 2 can be modified as shown in the example shown in FIG. During the change pulp 50
Instead, a normally open electromagnetic on-off valve 100 is used. The main mask cylinder 42 is connected to the sub mask cylinder 52 via an electromagnetic on-off valve 100, while the hydraulic brake 38.4
0 is always connected to the mask cylinder 52 on the side. Further, a bypass passage 102 is provided that bypasses the electromagnetic on-off valve 100, and a bypass passage 102 is provided in the middle of the bypass passage 102, which allows the flow of brake fluid from the main mask cylinder 42 side to the auxiliary mask cylinder 52 side, but prevents the flow in the opposite direction. Stop valve 10
4 are provided.

Further, between the sub mask cylinder 52 and the accumulator 54 and the reservoir 61, the electromagnetic directional control valve 56 is provided.
In place of the electromagnetic flow control valve 58, a normally closed am on-off valve 1 is used.
06 and a normally open electromagnetic on-off valve 108 are used. The sub mask cylinder 52 is connected to the accumulator 54 via the electromagnetic on-off valve 106, and to the reservoir 61 via the on-off valve 108.
It is connected to These electromagnetic on-off valves 1°O, 106, and 108 are connected to a control device 2110 as shown in FIG.

If the control device 110 determines that it is necessary to perform acceleration slip control, it continues to energize the solenoid of the electromagnetic on-off valve 100 to move the sub mask cylinder 52 to the main mask cylinder 42.
cut off from When the brake fluid pressure P7 of the hydraulic brake 38, 40 is rapidly increased, the control device 110 applies an excitation current with a high duty ratio to the solenoid of the electromagnetic on-off valve 106 while energizing the solenoid of the electromagnetic on-off valve 108. When the pressure is gradually increased, the solenoid of the electromagnetic on-off valve 108 is energized and a low duty is applied to the solenoid of the electromagnetic on-off valve 106. When supplying a specific excitation current and rapidly reducing the pressure, !
While energizing the solenoid of the breaker opening/closing valve 106, an excitation current with a low duty ratio is supplied to the solenoid of the electromagnetic opening/closing valve 108, thereby cutting off the sub-mask cylinder 52 from the accumulator 54 and communicating it with the reservoir 61. When the solenoid of the electromagnetic on-off valve 106 is demagnetized, an excitation current with a high duty ratio is supplied to the solenoid of the electromagnetic on-off valve 108, and when the pressure is maintained, the solenoid of the electromagnetic on-off valve 106 is demagnetized. At the same time, the solenoid of the electromagnetic on-off valve 108 is kept in an energized state, and the sub mask cylinder 52 is connected to the reservoir 61 from the Akiemulator 54 as well.
Also cut off from

As is clear from the above explanation, in this example,
Sub-mask cylinder 52. Accumulator 54, reservoir 61. Separate the speed sensor 66.6B, To, and open/close valve 100
, 106.108. Control device [110, electromagnetic on-off valve 11
A hydraulic pressure control device is comprised of parts that perform acceleration slip control of 0.0, 106.108, and the like.

In the embodiment detailed above, if a certain condition is satisfied among a plurality of conditions predetermined by the combination of rear wheel speed ■2 and rear wheel acceleration G2, the pressure increase/decrease mode corresponding to that condition is activated. If this condition is no longer satisfied and a different condition is met, a pressure increase/decrease mode corresponding to the different condition is determined. Both the start and end times of the determined pressure increase/decrease mode are determined based on the actual values of rear wheel speed V and rear wheel acceleration G1.

However, it is also possible to determine when to start and when to end the pressure increase/decrease mode under different conditions.

For example, if a certain condition is satisfied among a plurality of predetermined conditions for the slip ratio of the rear wheels 30.32, a pressure increase/decrease mode corresponding to that condition is determined, and the determined pressure increase/decrease mode is set in advance. You can set it to run only for a certain amount of time. When starting the determined pressure increase/decrease mode, the rear wheel speed is
, and the rear wheel acceleration G7, but the end time can be determined based on a predetermined time. In this case, the purpose of the pressure increase/decrease mode is not always achieved when the scheduled time has elapsed, and it may be necessary to continue the same pressure increase/decrease mode. Therefore, it is desirable to determine whether the purpose of the determined pressure increase/decrease mode has been sufficiently achieved at the end of the determined pressure increase/decrease mode, and to be able to continue the same pressure increase/decrease mode if the objective has not been achieved.

No matter what conditions determine when to start and end the pressure increase/decrease mode, the pressure increase mode is performed after the rear wheels 30. The present invention can be applied to any acceleration slip control device.

In addition to these, the present invention can be implemented in various modifications and improvements based on the knowledge of those skilled in the art, although they will not be illustrated individually.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, it is possible to determine when it is difficult to start with higher accuracy.
In addition to improving the accuracy of determining whether it is difficult to start, the acceleration of the vehicle when starting is easy is improved due to execution of inappropriate control patterns caused by incorrectly determining that it is difficult to start when starting is easy. The occurrence of a situation where there is a shortage of
The effect of improving acceleration feeling can be obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram conceptually showing the configuration of the present invention. FIG. 2 is a system diagram showing an acceleration slip control device which is an embodiment of the present invention. FIG. 3 is a block diagram showing details of the control device in FIG. 2. Figures 4 and 5
Each of the figures is a flowchart showing only a portion of the control program stored in the ROM in FIG. 3 that is particularly closely related to the present invention. FIGS. 6 and 7 are diagrams each showing a pressure increase/decrease mode selection table stored in the ROM for use in executing the flowchart in FIG. 4. FIG. 8 is a graph showing an example of control by the acceleration slip control device in FIG. 2. FIG. Fig. 9 shows the experimental results of the range of road surface μ in which starting is determined to be easy when starting a vehicle on a flat road, and the range of road surface μ in which starting is judged to be difficult. 3 is a graph shown for each example shown in FIG. Figure 1O is a graph showing the results of an experiment when the acceleration slip control device shown in Figure 2 performs difficult-to-start control when starting a vehicle on a flat and rough ice slope, and Figure 11 shows the difficult-to-start control. 12 is a graph showing the results of an experiment when easy-to-start control is performed instead of . FIG. 12 is a system diagram showing the main parts of an acceleration slip control device according to another embodiment. 1st
FIG. 3 is a block diagram showing details of the control device in FIG. 12. 30.32: Left and right rear wheels 38.40: Hydraulic brake 50: Change valve 52: Sub-mask cylinder 54:
Accumulator 56: Electromagnetic directional switching valve 58: Electromagnetic flow control valve 60.110: Control device 66.68: Left and right front wheel speed sensor 70: Rear wheel speed sensor 100° 106°

Claims (1)

[Claims] By controlling the hydraulic pressure of the wheel cylinder that operates the brakes of the driving wheels using different control patterns depending on whether the vehicle is easy to start and when it is difficult to start. An acceleration slip control device equipped with a hydraulic pressure control device that controls pressure to a height such that the slip of the driving wheels during vehicle acceleration is within an appropriate range, comprising: a vehicle speed detection means for detecting vehicle speed; timing detection means for detecting the start time of the pressure increase mode that is carried out for the first time after the drive wheels first exhibit a slip reduction tendency due to operation; and the vehicle body speed detection means when the timing detection means detects the start time. The vehicle is characterized by being provided with a difficult-to-start state determination means that compares the detection result with a predetermined threshold value and determines that the vehicle is in a difficult-to-start state if the detection result is less than or equal to the threshold value. Acceleration slip control device.