JPH08295222A - Antilock control device - Google Patents

Abstract

PURPOSE: To avoid extension of braking distance by providing the control means of a fluid pressure control device with a retention-time special pressure reduction execution means which constitutes normal pressure reduction control when a pressure reduction starting requirement different from that for normal pressure reduction control is met. CONSTITUTION: A first and a second solenoid switching valves 50, 56, a reservoir 54, a pump 62, and the like constitute a fluid pressure control device, and the portion of an electronic control unit 90 which performs special-duty pressure reduction control within the retention and execution times of normal-duty pressure reduction control constitutes a means for executing special pressure reduction during retention and execution. The portion of the electronic control unit 90 which executes a routine for measuring the retention time of the normal-duty pressure reduction control and which measures the expected retention and execution times constitutes 8 means for measuring the retention and execution times. Therefore wheels are rapidly restored from slip, and execution of the normal- duty pressure reduction control twice or more and extension of braking distance due to execution of sudden pressure reduction are avoided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antilock control device and, more particularly, to improving decompression control.

[0002]

2. Description of the Related Art A hydraulic pressure of a wheel cylinder in an anti-lock control device (hereinafter referred to as wheel cylinder pressure).
It may be desirable to gently reduce the pressure. In this case, the anti-lock control device includes (a) a hydraulic pressure control device that increases, decreases, and holds the hydraulic pressure of the wheel cylinder of the brake that suppresses wheel rotation, and (b) the hydraulic pressure control device. Control means to perform normal pressure reduction control consisting of pressure reduction and holding each time to reduce the hydraulic pressure of the wheel cylinder and maintain the slip state of the wheel in a proper state. Is configured as follows.

The anti-lock control device described in Japanese Patent Laid-Open No. 1-182155 is an example thereof. In this antilock control device, the hydraulic pressure control device control means normally carries out the pressure reduction control by duty control consisting of pressure reduction and holding once. A duty ratio determination map that defines a plurality of types of duty pressure reduction patterns with different ratios of pressure reduction time and holding time is provided, and the duty pressure reduction pattern is selected based on the slip rate of the wheels and the time change rate of the slip rate. The decompression time and the holding time are determined, and the decompression and the holding are performed. If the wheel cylinder pressure is gradually reduced by the duty reduction including the pressure reduction and the holding, the antilock control can be finely performed. Further, even if the duty reduction is continuously performed a plurality of times (for example, twice), if the slip state defined by the slip ratio, the slip amount, the wheel acceleration, etc. does not become an appropriate state, continuous operation without holding is performed. It is also known to perform pressure reduction control to rapidly reduce the wheel cylinder pressure.

[0004]

In the conventional antilock control device described above, the sense of deceleration may be insufficient. For example, when a driver generally has a high level of driving operation technology and can drive the vehicle with stability even if the wheels have a large slip, such as a sports specification vehicle,
If the decompression suitable for an ordinary driver is performed, the decompression amount becomes excessive and it is difficult to obtain a sufficient deceleration feeling. In such a case, if the decompression time in the normal decompression control is shortened, the decompression amount is reduced and the feeling of deceleration can be enhanced. In particular, it is effective to shorten the decompression time on a road surface having a high friction coefficient (referred to as a high μ road). But in this case,
If a deep slip should occur on a high μ road, the amount of pressure reduction is insufficient in one duty pressure reduction control and the duty pressure reduction control is executed a plurality of times, during which slip recovery is delayed and the braking distance is extended. Even when the duty pressure reducing control is performed a plurality of times, the pressure reducing amount is still insufficient and the continuous pressure reducing control is performed. On the contrary, the pressure reducing becomes excessive and the braking distance may be extended.

The inventor of the present invention has encountered this phenomenon in the process of converting an antilock control device for a normal specification vehicle into an antilock control device for a sports specification vehicle. As a type of anti-lock control device for normal specification vehicles, the decompression time and the holding time are usually determined according to the duty ratio determination map for both the front wheels and the rear wheels. If the duty ratio is corrected so that the decompression time is longer than when the decision map is followed, and if the decompression amount is still insufficient after performing the duty decompression control twice for both the front wheels and the rear wheels, sudden decompression is performed. Some anti-lock control devices are designed to perform control, while shortening the decompression time for high μ roads and eliminating the duty ratio correction during the first decompression of the rear wheels. I tried to change it to the anti-lock control device of the specification car. As a result, the result is that the braking distance is generally shortened and the feeling of deceleration is improved, but in special cases, for example, an excessively small wheel acceleration (excessive wheel deceleration) at the initial stage of the duty reduction control. In the case of occurrence of a slip, or when the slip that has started to recover once starts to increase again in the middle, normally, one duty reduction control is sufficient, but the second duty reduction control is performed. It has been found that there is a case where a sufficient deceleration feeling is not obtained due to a breakage or sudden decompression control, and the braking distance is rather extended.

Therefore, the present invention provides an antilock control device which can obtain a large deceleration as a whole and can prevent the braking distance from being extended even in a special case such as the above two cases. It was a task to provide.

[0007]

In order to solve the above-mentioned problems, the present invention provides (a) a hydraulic control device and (b).
When a pressure reduction start condition different from the pressure reduction start condition of the normal pressure reduction control is satisfied during execution of holding of the normal pressure reduction control, the hydraulic pressure control device control means of the antilock control device including the hydraulic pressure control device control means The present invention is characterized in that a holding-in-execution special decompression executing means for performing special decompression for a time shorter than a holding execution time which constitutes the pressure reduction control is provided.

[0008]

In the anti-lock control device configured as described above, special decompression is performed if the special decompression start condition is satisfied while the normal decompression control is being held, and the shortage of decompression amount due to the normal decompression control is compensated. . Usually, sufficient deceleration is ensured by the normal pressure reduction control with a short pressure reduction time, and in special cases, additional pressure reduction is performed during the holding time of the normal pressure reduction control. If the holding time of the normal pressure reducing control is shortened to shorten the execution time of the entire normal pressure reducing control so that the normal pressure reducing control can be executed a plurality of times in a short time, the pressure reduction amount is insufficient. Although the problem can be solved, in this case, whether or not the next normal depressurization control is necessary is determined before the depressurization effect sufficiently appears, because the elapsed time (holding time) from the completion of depressurization is short. Therefore, it is likely that the amount of pressure reduction is determined to be insufficient, and unnecessary normal pressure reduction control is repeated to cause an excessive amount of pressure reduction. For it,
In addition to the normal decompression control start condition, if the decompression start condition corresponding to the occurrence of a special situation is set and the special decompression is performed as necessary during the holding execution of the normal decompression control,
Unlike the case where the normal decompression control is repeatedly executed in a short time, it is possible to wait until the effect of the decompression is fully realized so as to determine whether or not the next normal decompression control is necessary. In addition, special decompression can be performed when a special situation occurs. Note that the special decompression here is as described in the section of Examples,
The pressure reduction may be performed by depressurizing and holding once, or only depressurizing without holding.

[0009]

As described above, according to the present invention, the decompression time of the normal decompression control, which consists of decompression and holding once, is set short to obtain a sufficient deceleration feeling. By performing the above, it is possible to prevent the braking distance from being extended in a special case.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The preferred embodiments of the present invention will be listed below, and related explanations will be given if necessary. (1) The special decompression executing means during the holding execution, after decompression,
4. A special decompression start determining means for deciding whether or not to perform special decompression after a lapse of a certain time is included.
The anti-lock control device described in. According to the device of this aspect, it is determined whether or not to execute the special pressure reduction after waiting for the effect of the pressure reduction to some extent, at least one of after the pressure reduction in the normal pressure reduction control and after the end of the special pressure reduction, Unnecessary decompression is avoided. In order to determine whether or not the special depressurization should be performed after the depressurization is finished and after a certain period of time elapses, for example, the waiting time measurement is started at the same time when the depressurization is finished, and the waiting time is set to be the set time or more. If the need for special decompression is determined when it becomes, or if the execution cycle time of the program for determining the necessity of special decompression is set to a length at which the determination is made after a certain time has elapsed after the decompression ends. Good. For example, the decompression time of the normal decompression control and the decompression time of the special decompression may be the longer decompression time plus a certain time as the execution cycle time of the special decompression execution determination program. (2) The anti-lock control device according to claim 1, wherein the holding special pressure reducing execution means includes a constant special pressure reduction start determining means for determining whether or not to always perform the special pressure reduction at least after the pressure reduction ends. According to the apparatus of this aspect, it is possible to promptly grasp the occurrence of a situation where special decompression is required and perform decompression without delay. Further, according to the apparatus of this aspect, when the special decompression is executed by decompressing and holding once, if the special decompression start condition is not satisfied during the decompression, the decompression is canceled on the way. If the special decompression is performed only by the decompression, the determination can be made at the end of the decompression, and the decompression can be continuously performed if the special decompression start condition is satisfied. (3) The antilock control device according to aspect 2, wherein the start condition of the special decompression includes holding at least for a certain period of time after the decompression ends. After the decompression is completed, if the holding of a certain time is performed as a special decompression starting condition, even if it is determined whether or not the special decompression should be performed immediately after the decompression of the normal decompression control, We can wait for the effect of decompression to appear. (4) The start condition of the special decompression includes at least that the wheel acceleration is equal to or less than a set acceleration.
The anti-lock control device according to any one of 3 above. Even if the wheel cylinder pressure is reduced, the amount of pressure reduction is insufficient,
The slip may not tend to recover due to reasons such as the road surface friction coefficient decreasing during antilock control, but this fact can be seen by the fact that the wheel acceleration is below the set acceleration even at the time of judgment, and the special decompression Is performed so that the slip tends to recover. The wheel acceleration is detected by the wheel acceleration detecting means. The wheel acceleration detecting means may be, for example, one that obtains the wheel acceleration by calculation from the wheel speed. (5) The normal decompression start condition includes that the wheel acceleration is equal to or less than a set acceleration, and the set acceleration in the special decompression start condition is smaller than the set acceleration in the normal decompression start condition. Anti-lock control device. (6) The antilock control device according to aspect 4 or 5, wherein the special decompression start condition further includes that the road surface is a good road. A good road is, for example, that there are few irregularities. If the road surface is uneven, the wheel rotation speed fluctuates greatly and the slip amount and rate temporarily increase. However, since this increase is temporary, it is not necessary to reduce the wheel cylinder pressure. However, if the road surface is a good road with few irregularities and the wheel acceleration is less than the set acceleration, it is usually necessary to reduce the wheel cylinder pressure, so it is necessary to start special decompression when the road surface is a good road. It is a condition. The unevenness of the road surface is detected by the road surface unevenness detecting means. The road surface unevenness detecting means is configured to detect road surface unevenness based on, for example, fluctuations in wheel acceleration. When the wheel passes over the unevenness of the road surface, the fluctuation of the wheel speed becomes large. Therefore, for example, whether the wheel is on the uneven road surface can be detected based on the frequency at which the wheel acceleration exceeds the set acceleration. (7) The antilock control device according to any one of aspects 4 to 6, wherein the special decompression starting condition further includes a high road surface friction coefficient. On a road surface with a low coefficient of friction, the wheels easily slip and the wheel speed changes with a steep slope.Therefore, it is necessary to change the wheel cylinder pressure little by little while watching the wheel speed. Not desirable to do. On the other hand, on a road surface with a high coefficient of friction,
Wheels do not easily slip, and the wheel speed usually changes with a relatively gentle gradient.If the wheel acceleration is less than the set acceleration, it is assumed that a special situation has occurred and the pressure is further reduced by special decompression. Is desirable. The road surface friction coefficient is detected by the road surface friction coefficient detecting means. The road surface friction coefficient detecting means may be configured, for example, to estimate the vehicle body speed and the vehicle body deceleration from the wheel acceleration, and determine that the larger the vehicle body deceleration, the larger the road surface friction coefficient. In addition, a longitudinal acceleration sensor for detecting the longitudinal acceleration of the vehicle or a Doppler type vehicle body speed sensor for the ground is provided, and the road surface friction coefficient is calculated based on the vehicle body deceleration detected by these and the vehicle body deceleration calculated from the vehicle body speed. It may be detected. (8) The antilock control device according to any one of claims 1 and 1 to 7, further comprising a special decompression time determining means for determining the special decompression time. The special decompression time may be set based on the wheel acceleration, or may be obtained by multiplying the decompression time of the normal decompression control by a set ratio, and can be determined by various means. It should be noted that it may be set in advance according to the vehicle type and the like, and in this case, the special decompression time determining means is unnecessary. (9) The special depressurization is performed by depressurizing and holding once, and the sum of the execution times of the depressurizing and holding once each is shorter than the holding execution time in the normal depressurization control. The anti-lock control device according to any one of 1 to 8. In the apparatus of this aspect, the depressurization control generally includes once depressurization and holding, and can be regarded as a device in which the depressurization and holding are performed specially during the holding, or the depressurizing control is usually performed. Includes a plurality of depressurization patterns including depressurization and holding each time, but the depressurization patterns for the second time and thereafter can be regarded as an apparatus that is executed only in special cases. Whether or not the start condition of the special decompression is satisfied is constantly determined, and if the start condition is not satisfied during the decompression or holding of the special decompression, the execution of the special decompression may be stopped, or Judgment is always made, but decompression and holding for a fixed time are executed,
Based on the determination result at the end of those executions, the next special pressure reduction may be performed if the special pressure reduction start condition is satisfied, or may not be performed if the special pressure reduction start condition is not satisfied. In the latter case, if the special depressurization start condition is not satisfied when the execution time of depressurization and holding has elapsed, the determination is repeatedly executed thereafter, and the special depressurization is performed when the conditions are satisfied. Further, the determination may be performed every time the execution time of depressurization and holding elapses. When the special depressurization start condition is not satisfied, the holding is executed until the execution time of the depressurization and the holding elapses and the determination is made next. This can be realized, for example, by measuring the execution time or by setting the execution cycle time of the program for determining whether or not the special depressurization start condition is satisfied. In the anti-lock control device of this aspect, the hydraulic pressure control device control means executes the unit pattern pressure reduction consisting of the pressure reduction and the holding once, respectively, in principle, a plurality of predetermined number of times. The execution of the first depressurizing means to stop and hold if the first condition is not satisfied, and the first depressing means to command the pattern depressurizing means to start operation when a second condition different from the first condition is satisfied. When the third condition different from the first condition and the second condition is satisfied at the end time of the operation of the operation start commanding means and the pattern pressure reducing means started to operate by the first operation start commanding means, the pattern pressure reducing operation is performed. It can be said that the second operation start command means for reactivating the means is provided.
The third condition is different from the first condition, but may be the same as the second condition. Further, when the operation of the pattern pressure reducing means is finished, the number of determinations as to whether or not the special pressure reducing start condition is satisfied,
That is, it can be understood by counting the number of unit patterns,
Alternatively, it can be found by measuring the elapsed time from the start of the operation of the pattern pressure reducing means to the execution time of one unit pattern times the predetermined number of times of execution of the unit pattern. (10) The special decompression performed by decompressing and holding once each is performed by duty control, and the special decompression time determining means determines the decompression time by determining the duty ratio between the decompression time and the holding time. 10. The anti-lock control device according to aspect 9, which is a duty ratio determining means for performing. The duty ratio may be determined in advance, or may be determined when the special pressure reduction start condition is satisfied. In the latter case, for example, a duty ratio determination map that determines the duty ratio may be set so that the pressure reduction time becomes longer as the wheel acceleration becomes smaller when the special pressure reduction start condition is satisfied, and the duty ratio may be selected. When the control is performed by the duty reduction control, the duty ratio of the normal duty reduction control may be set to the duty ratio of the special duty reduction control, or the duty ratio of the normal duty reduction control may be determined by multiplying by the set ratio. Can be determined in the following manner. When the special pressure reduction control is performed a plurality of times, the duty ratio of the special pressure reduction control for each time may be the same or may be determined for each time according to the slip state of the wheel. (11) The antilock control device according to any one of claims 1 and 1 to 10, wherein the decompression time of the special decompression is the same as the decompression time of the normal decompression control. (12) The antilock control device according to any one of claims 1 and 1 to 10, wherein the decompression time of the special decompression is different from the decompression time of the normal decompression control. (13) The depressurizing times of a plurality of special depressurizing operations performed during the holding operation have the same length as each other.
The anti-lock control device according to any one of 1. (14) The depressurization time of a plurality of special depressurizations performed during the holding is different in length from each other.
The anti-lock control device according to any one of 1. For example, the decompression time is lengthened as the number of executions of the special decompression increases. (15) After the normal pressure reduction control, when a condition different from the start condition of the normal pressure reduction control and the start condition of the special pressure reduction is satisfied, a normal pressure reduction control repeating unit that performs the normal pressure reduction control again is included. Item 15. The antilock control device according to any one of items 1 to 1-14. For example, two kinds of control mode selection maps are prepared to select the wheel cylinder pressure control mode, that is, whether to increase, hold, or reduce the wheel cylinder pressure, and the normal pressure reduction control is the first time or the second time. If the control mode is selected according to the different control mode selection map, the start condition of the second normal pressure reducing control can be made different from that of the first normal pressure reducing control and the special pressure reducing control. The two different control mode selection maps are
Elements for selecting the control mode (eg wheel acceleration,
It is obtained by making at least one of the vehicle body deceleration) and the threshold value different. (16) When the same condition as the starting condition of the normal pressure reducing control is satisfied after the end of the normal pressure reducing control, including the normal pressure reducing control repeating means when the same condition for performing the normal pressure reducing is satisfied.
The anti-lock control device according to any one of aspects 1 to 15. (17) The special decompression ending means for terminating the special decompression when the execution time of the normal decompression control elapses.
16. The anti-lock control device according to any one of 16 to 16.
According to the apparatus of this aspect, if the execution time of the normal decompression control elapses, the special decompression can be terminated even in the middle, and the execution time of the normal decompression control does not become long. (18) The antilock control device according to aspect 17, which includes a normal pressure reduction control execution time elapse determination unit that determines whether the execution time of the normal pressure reduction control has elapsed. (19) The normal decompression control execution time elapse determination unit includes a planned retention execution time measuring unit for measuring a planned retention execution time of the normal decompression control, and the normal decompression control execution time depends on whether the planned retention execution time has elapsed. 19. The antilock control device according to aspect 18, which determines whether or not has elapsed.
Although it is possible to know whether or not the execution time of the normal pressure reduction control has elapsed by measuring the total execution time of the pressure reduction and the holding each time from the start of the normal pressure reduction control, in the normal pressure reduction control, the holding pressure is reduced. Is usually performed after, and the elapse of the execution time of the normal pressure reduction control can be determined by measuring the scheduled holding execution time. (20) The antilock control according to any one of claims 1 and 1 to 19, further comprising a special decompression canceling means for canceling the execution of the special decompression when the special decompression starting condition is not satisfied during execution of the special decompression. apparatus. When the special depressurization is executed by depressurizing and holding once, if the special depressurization start condition is not satisfied during depressurization, the depressurization is stopped and the holding is executed.
If the special depressurization start condition is not satisfied during the holding, the holding of the special depressurization is stopped and the normal depressurization control is held. To be done. When the special decompression is performed only by the decompression, if the special decompression start condition is not satisfied during the execution of the special decompression, the decompression is stopped and the normal decompression is executed, and the extra decompression is avoided. It

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A hydraulic brake device having an antilock control device according to an embodiment of the first invention will be described in detail below with reference to the drawings. In FIG. 1, 10 is a brake pedal as a brake operating member. In response to the depression operation of the brake pedal 10, hydraulic pressures of the same height are generated in two independent pressurizing chambers of the master cylinder 12. 14
Is a reservoir that is attached to the master cylinder 12 and supplies brake fluid to the master cylinder 12.

The hydraulic pressure generated in one pressurizing chamber of the master cylinder 12 is transmitted to the wheel cylinder 22 of the brake of the left front wheel 20 by the liquid passages 16 and 18, and the liquid passage 1
6, 24 is transmitted to the wheel cylinder 28 of the brake for the right rear wheel 26. The hydraulic pressure generated in the other pressurizing chamber of the master cylinder 12 is transmitted to the wheel cylinder 36 of the brake of the right front wheel 34 by the liquid passages 30 and 32,
It is transmitted to the wheel cylinder 42 of the brake of the left rear wheel 40 by the liquid passages 30 and 38. The braking device of this embodiment is a cross piping type braking device.

The hydraulic pressure transmitted from the master cylinder 12 to the wheel cylinders 28, 42 is proportionally reduced by the dual proportioning valve 44 in a region of a predetermined height or higher. According to the dual proportioning valve 44, the hydraulic pressure (hereinafter, referred to as wheel cylinder pressure) of both wheel cylinders 28 and 42 is irrespective of the manufacturing error of each component of the two proportioning valves constituting the dual proportioning valve 44. The pressure is precisely controlled to the same level, and the depressurization start hydraulic pressure in the normal system when the failure of one system is increased to almost double that in the normal system.

Left and right front wheels 20, 34 and rear wheels 40, 2
Each of the six wheels is independently antilock-controlled for the four wheels.
Therefore, although an anti-lock control actuator is provided for each of the four wheels, the configurations are the same, and the left front wheel system will be described as an example. The liquid passage 16 is provided with a normally open first electromagnetic opening / closing valve 50. Between the wheel cylinder 22 of the liquid passage 18 and the first electromagnetic opening / closing valve 50, a reservoir 54 is connected to the reservoir 54 and a normally closed second electromagnetic opening / closing valve 56 is provided. The combination of the opening and closing of the first and second electromagnetic on-off valves 50, 56 increases, decreases or maintains the wheel cylinder pressure.

The brake fluid flowing from the wheel cylinder 22 to the reservoir 54 is pumped up by a pump 62 driven by a pump motor 60, and a pump passage 64 is formed.
Is returned from the liquid passage 16 between the first solenoid on-off valve 50 and the master cylinder 12. The liquid passage 16 is provided with a bypass passage 70 that bypasses the first electromagnetic on-off valve 50 and has a check valve 68. The check valve 68 allows the flow of the brake fluid from the wheel cylinder 22 to the master cylinder 12, but blocks the reverse flow of the brake fluid. The check valve 68 prevents the brake pedal 10 from closing when the first electromagnetic opening / closing valve 50 is closed.
When the depression of the wheel cylinder is released, the brake fluid in the wheel cylinder 22 returns to the master cylinder 12 through the bypass passage 70, and the wheel cylinder pressure changes to the brake pedal 10.
It can be lowered to a height commensurate with the stepping force of.

Left and right front wheels 20, 34 and rear wheels 40, 2
The respective rotation speeds of 6 are the rotation speed sensors 80, 82, 84,
86, and the detection result is the electronic control unit 90.
Is supplied to. The electronic control unit 90 is mainly composed of a computer, and its RAM has a control mode memory 100, a duty ratio memory 102,
Pressure reduction time memory 104, holding time memory 106, measurement start time memory 107, cumulative holding time memory 108, normal duty pressure reduction control start flag 110, special duty pressure reduction control start flag 112, normal duty pressure reduction control holding start flag 114, holding time A measurement flag 115 and a hold interruption flag 116 are provided together with the working memory. Further, the ROM includes rotation speed sensors 80 to 86.
A vehicle speed calculation routine for calculating wheel speed, wheel acceleration, vehicle body speed, vehicle body deceleration, etc. based on the detection signal of
5 is a main routine shown in FIG. 3, a hydraulic control routine shown in FIG. 4, and an antilock control routine for controlling the first and second electromagnetic on-off valves 50 and 56 and the pump motor 60 to perform antilock control. The pressure reduction control command output routine shown in FIG. 6 and the normal duty pressure reduction control holding time measurement routine shown in FIG. 6 are stored. In order to execute these programs, the electronic control unit 90 is connected to a brake switch 120 that detects depression of the brake pedal 10.

Next, the operation will be described. Brake pedal 10
In the state in which is not depressed, the first and second solenoid on-off valves 50, 56 are in the state shown in FIG. 1, and the wheel cylinders 22, 28, 36, 42 are in communication with the master cylinder 12. If the brake pedal 10 is depressed,
The hydraulic pressure generated in the pressurizing chamber of the master cylinder 12 is transmitted to the wheel cylinders 22, 28, 36, 42, and the rotations of the left and right front wheels 20, 34 and the left and right rear wheels 40, 26 are suppressed. When the depression force of the brake pedal 10 is excessive with respect to the friction coefficient of the road surface and the slip of the wheels increases beyond the proper range, the routines of FIGS. 3 to 6 are sequentially executed every 6 ms to perform antilock control. Is done. The antilock control will be described below by taking the left front wheel 20 as an example. First,
The main routine shown in FIG. 3 is executed. Step S1
(Hereinafter, abbreviated as S1. The same applies to other steps.), And initial settings such as clearing the memories 100 to 108 and resetting the flags 110 to 116 are performed.

Next, after the wheel speed Vw and the wheel acceleration DVw are calculated in S2, the wheel speed Vw is calculated in S3.
And the vehicle speed V _SO is calculated based on the wheel acceleration DVw. The calculation of the vehicle body speed V _SO is already known and will not be described. Subsequently, S4 is executed, the slip ratio ΔV of the wheels is calculated based on the wheel speed Vw and the vehicle body speed V _SO , and the vehicle body deceleration DV _SO is calculated. Then, S5 is executed and the control mode of the wheel cylinder pressure is changed. To be selected. Although the vehicle body is only decelerated during braking, both deceleration and acceleration occur on the wheels due to increase and decrease of slip.
Therefore, the vehicle body is referred to as vehicle body deceleration, and the wheels are referred to as wheel acceleration. Wheel deceleration is negative wheel acceleration.

The control modes include a pulse pressure increasing mode, a holding mode, a duty decreasing mode and a rapid decreasing mode.
There are types. The pulse pressure increasing mode is a mode in which the pressure is increased for a certain period of time at regular intervals to gradually increase the wheel cylinder pressure, and the holding mode is a mode of keeping the wheel cylinder pressure at a constant height. The duty depressurization mode is a mode in which the wheel cylinder pressure is gently reduced by performing the pressure reduction and holding once each for a time determined by the duty ratio, and in the rapid pressure reduction mode, the wheel deceleration is performed only by continuously reducing the pressure. This is a mode in which the cylinder pressure is rapidly reduced.

The control mode can be selected on the basis of various rules, and in the present embodiment, it is selected on the basis of a map created using the wheel slip ratio and the wheel acceleration. This control mode selection map is one in which the control modes are set for each of a plurality of combinations of wheel slip ratio and wheel acceleration that are divided into a plurality of stages, and are stored in the ROM of the computer. The control mode selection map is
As the absolute value of the negative wheel acceleration is larger, the mode is on the pressure reducing side, and as the absolute value is smaller, the mode is on the pressure increasing side, and the control mode is selected based on the calculated slip ratio and the wheel acceleration. However, the duty pressure reduction mode and the rapid pressure reduction mode are selected as pressure reduction modes including both, and the duty pressure reduction mode is selected when the slip ratio ΔV is equal to or less than the set slip ratio, and the rapid pressure reduction mode is selected when the slip ratio ΔV exceeds the set slip ratio. It Control mode selection is always performed using the same control mode selection map. However, when the duty reduction mode is selected three times in succession, the duty reduction mode for the third time is changed to the rapid reduction mode. The control mode selection map is
The front wheel and the rear wheel may be the same, but they are different in this embodiment.

If the selected control mode is the pulse pressure increasing mode, S6 is executed, and the data indicating that the selected control mode is the pulse pressure increasing mode is stored in the control mode memory 100. If it is the holding mode, S
7, the holding mode is selected as the control mode memory 100.
If the duty reduction mode is stored in the control mode memory 1 in step S8.
00, and if it is the rapid pressure reduction mode, the selection of the rapid pressure reduction mode is stored in the control mode memory 100 in S9.

Next, the fluid pressure control routine shown in FIG. 4 is executed. First, it is determined whether or not the control mode selected in S11 is the pulse pressure increasing mode. If the pulse pressure increasing mode is selected, the determination result of S11 is YES, and the pulse pressure increasing process of S12 is performed. The pressure increase command is output at regular time intervals, and the first electromagnetic opening / closing valve 50 is opened based on the output. When the pressure increase command is not output, the hold command is output and the first and second electromagnetic on-off valves 50 and 56 are closed to hold the wheel cylinder pressure. If the selected control mode is the hold mode, S
The determination result of 11 is NO, the determination result of S13 is YES, S14 is executed, and the first and second solenoid on-off valves 50, 5 are executed.
6 is closed and the wheel cylinder pressure is maintained. If the selected control mode is the rapid depressurization mode, S11,1
The determination result of 3 is NO, the determination result of S15 is YES, S16 is executed, and the wheel cylinder pressure is continuously reduced. The first solenoid on-off valve 50 is closed and the second solenoid on-off valve 56 is opened, so that the wheel cylinder 22
The brake fluid continuously flows out of the reservoir 54 to the reservoir 54, and the wheel cylinder pressure is rapidly reduced.

Since the pulse pressure increasing process, the holding process and the rapid pressure decreasing process are not directly related to the present invention, the illustration and description of the process routine are omitted. In each of these processing routines, when the control mode executed immediately before the selected control mode is different from the selected control mode, the flags set in the processing routines of other control modes and the memory Execution end processing of another control mode such as clear is performed. If the control mode is the duty reduction mode, the determination results of S11, 13, and 15 are NO, and the duty reduction process is performed in S17. The program for the duty reduction processing is a pressure reduction control command output routine that outputs a pressure reduction control instruction, a duty reduction control execution routine that executes pressure reduction and holding based on the instruction, and a normal duty pressure reduction control that measures the holding execution time. A holding time measurement routine and the like are included, and only programs closely related to the present invention will be shown and described below.

During the duty reduction processing, the pressure reduction control command output routine shown in FIG. 5 is executed. This program determines the duty ratio of the duty reduction control, outputs the start instruction of the duty reduction control, and, while holding the duty reduction control, the condition different from the selection condition of the duty reduction mode in the control mode selection map When established, another start command for the duty reduction control is output. Hereinafter, the duty reduction control executed by selecting the control mode selection map will be referred to as normal duty reduction control, and the duty reduction control executed while the normal duty reduction control is held will be referred to as special duty reduction control.

First, it is determined whether or not the normal duty pressure reducing control has been started depending on whether or not the normal duty pressure reducing control start flag 110 is set in S21. The normal duty pressure reducing control start flag 110 is reset in the initial setting of the main routine, and when S21 is executed for the first time, the determination result is NO.
Then, S22 is executed, the duty ratio is determined and stored in the duty ratio memory 102. The duty ratio is selected from the duty ratio determination map stored in the ROM. The map is created based on the wheel acceleration DVw and the vehicle body deceleration DV _SO, it is set duty ratio according to a combination of each with the wheel acceleration DVw and the vehicle body deceleration DV _SO divided into a plurality of stages. The duty ratio is such that as the vehicle body deceleration DV _SO is larger and the wheel acceleration DVw is smaller, the decompression time becomes longer, and as the vehicle body deceleration DV _SO is smaller and the wheel acceleration DVw is larger, the decompression time becomes shorter. And the road friction coefficient is high, that is, the vehicle body deceleration DV _SO
On the high side, the decompression time is set to be shorter than that for the normal specification vehicle, and the duty ratio determination map for the sports specification vehicle is set. The duty ratio in this duty ratio determination map is set to various values from a value shorter than the cycle time 6 ms of each routine of FIGS. 3 to 6 to a value longer than that of the routine duty pressure reduction control. The duty ratio determination map may be the same for the front wheels and for the rear wheels, but different in this embodiment.

Next, S23 is executed, and a normal duty pressure reducing control start command is output. Since the normal duty pressure reduction control start flag 110 is set, a duty pressure reduction control execution routine (not shown) is performed thereby. The duty reduction control execution routine calculates the pressure reduction time and the holding time based on the set duty ratio and stores them in the pressure reduction time memory 104 and the holding time memory 105. First, the pressure reduction is executed for the set time and the holding is performed for the set time. Is configured to run. In the duty reduction control execution routine, execution termination processing of another control mode that was performed immediately before the start of the duty reduction control is also performed.

Normal duty pressure reduction control start flag 110
Is set, the next time S21 is executed, the determination result is YES and S24 is executed.
It is determined whether or not the special duty pressure reducing control is being executed. This determination is made based on whether or not the special duty pressure reduction control start flag 112 is set.
The special duty pressure reducing control start flag 112 is reset in the initial setting, and when S24 is performed for the first time, the determination result is NO. Next, S25 is executed, and it is determined whether or not the normal duty pressure reducing control is being held. This determination is made based on whether or not the normal duty pressure reducing control holding start flag 114 is set. The holding start flag 114 for normal duty pressure reduction control is set when the pressure reduction is completed and the holding is started in the duty pressure reduction control execution routine,
It is reset when the scheduled holding execution time of the normal duty pressure reduction control elapses (there is a case where the special duty pressure reduction control is not executed and a case where the special duty pressure reduction control is executed).

When S25 is executed, there are cases where the pressure reduction is still being executed and cases where the pressure reduction is finished and the holding is being executed. In the former case, the determination result of S25 is NO and S26 and the following steps are executed. Although it is skipped, it is executed in the latter case, and it is determined in S26 to 28 whether or not the start condition of the duty reduction control during the holding execution, that is, the special duty reduction control is satisfied. The conditions for starting the special duty pressure reduction control are that the road surface is a good road with few irregularities, that the road surface friction coefficient is high, that the wheel acceleration is less than or equal to the set acceleration, that is, that the front wheel is -7 G or less,
For the rear wheels, it is -5 G or less. On the other hand, as described above, the conditions for starting the normal duty pressure reducing control are that the wheel acceleration is equal to or less than the set acceleration, and the wheel slip rate is the set slip rate. As described above, the two are different, and the special duty pressure reducing control is started by the establishment of a special starting condition different from the normal duty pressure reducing control. Note that the set acceleration of the special duty pressure reducing control start condition is smaller than the minimum value of the plurality of setting accelerations of the normal duty pressure reducing control start condition (the plurality of setting accelerations for which the duty pressure reducing mode is selected in the control mode selection map). Is.

The road surface friction coefficient is estimated from the vehicle body deceleration. The larger the vehicle body deceleration, the larger the road surface friction coefficient. In this embodiment, when the vehicle body deceleration is 0.6 G or more, the road surface friction coefficient is high. Whether or not the wheel is on the uneven road surface is determined based on the frequency at which the wheel acceleration exceeds the set acceleration. The computer determines whether or not a situation in which the wheel acceleration becomes equal to or higher than a set acceleration occurs a predetermined number of times or more within a set time, and if the number is less than the predetermined number of times, the road surface unevenness detection routine determines that the road surface is a good road with less unevenness. Is provided and is always executed. In S26, the detection result of this is read to determine whether or not the road surface is a good road.

If any one of the conditions for starting the special duty pressure reducing control is not satisfied, the execution of this routine ends and the special duty pressure reducing control is not performed. On the other hand, if all the execution conditions of the special duty pressure reducing control are satisfied, S29 is executed and the holding of the normal duty pressure reducing control is interrupted. The hold interruption flag 116 is set, then S30 is executed and a special duty pressure reducing control start command is output. The special duty pressure reduction control start flag 112 is set. As a result, in the duty reduction control execution routine, pressure reduction and holding are performed instead of holding, and first, the second electromagnetic opening / closing valve 56 is opened for a set time to allow the brake fluid to flow out from the wheel cylinder. The duty ratio of the special duty pressure reducing control is set in advance, and the pressure reducing time and the holding time are set based on the duty ratio. In this embodiment, the depressurization time is set to 4 ms and the holding time is set to 10 ms.

If the special duty pressure reducing control is started,
When S24 is executed next, the determination result is YES. This is because the time of the special duty pressure reducing control is 14 ms in total including the pressure reducing time and the holding time, which is longer than the execution cycle time 6 ms of the pressure reducing control command output routine. Next, S31 is executed to hold the normal duty pressure reducing control. It is determined whether it is within the scheduled time. This determination is made based on whether or not the holding execution time of the normal duty pressure reducing control stored in the cumulative holding time memory 108 is within the holding execution scheduled time.

The holding execution time of the normal duty pressure reducing control is measured by executing the normal duty pressure reducing control holding time measuring routine shown in FIG. Whether or not the holding of the normal duty pressure reducing control is started in S41 is determined by whether or not the normal duty pressure reducing control holding start flag 114 is set. If the holding of the normal duty pressure reducing control is not started, the determination result of S41 is NO, and the execution of this routine ends. In the duty reduction control execution routine, pressure reduction is completed,
If the holding of the normal duty pressure reducing control is started and the holding start flag 114 for the normal duty pressure reducing control is set, the determination result of S41 is YES, S42 is executed, and whether the holding time measurement flag 115 is set or not. As a result, the determination result of S41 is YES, and it is determined whether or not it is the second or subsequent execution. If the determination result is NO, the value T _{1 of the} timer (not shown) provided in the computer is read in S42, stored in the measurement start time memory 107, and the holding time measurement flag 11 is stored.
5 is set. Therefore, when S42 is executed next time, the determination result becomes YES, the time of the timer is read in S44, and the time of the measurement start time memory 107 is subtracted from the read time to obtain the cumulative holding time. , Are stored in the cumulative holding time memory 108. Hold start flag 1 for normal duty pressure reduction control
14 and the holding time measurement flag 115 are not reset even if the holding is interrupted, and even during the special duty pressure reducing control,
The holding time of the normal duty pressure reducing control is measured.

If the holding time is within the scheduled holding execution time of the normal duty pressure reducing control, the determination result of S31 of the pressure reducing control command output routine is YES, and the continuation condition of the special duty pressure reducing control is satisfied in S32 to S34. It is determined whether or not there is. In the present embodiment, the continuation condition of the special duty pressure reduction control is the same as the start condition of the special duty pressure reduction control, and this determination is performed in the same manner as S26 to 28, and if all the continuation conditions are satisfied, this routine is performed. The execution of is ended as it is, and the holding of the special duty pressure reducing control is continued.

During execution of the holding of the special duty pressure reducing control, if all the continuation conditions of the special duty pressure reducing control are continuously satisfied and the holding time of the special duty pressure reducing control elapses,
In the duty reduction control execution routine, the special duty pressure reduction control is ended, and the normal duty pressure reduction control is resumed. The special duty pressure reduction control start flag 112 and the hold interruption flag 116 are reset.

Therefore, when S24 is executed after the end of the special duty pressure reducing control, the determination result is NO, the determination result of S25 is YES and S26 to 28 are executed, and the start condition of the special duty pressure reducing control is executed. It is determined whether or not is satisfied. After the previous decompression of the special duty decompression control is completed, it is determined whether or not the special duty decompression control should be performed when the holding time of the special duty decompression control of 10 ms or more has elapsed, and the effect of the decompression appears to some extent. After waiting for, it is determined whether or not the next special decompression is necessary. If all the conditions for starting the special duty pressure reducing control are satisfied, the special duty pressure reducing control is executed again.

If the scheduled holding execution time of the normal duty pressure reduction control elapses without the start condition of the special duty pressure reduction control being satisfied, the normal duty pressure reduction control is ended in the duty pressure reduction control execution routine. The duty ratio memory 102, the pressure reducing time memory 104, the holding time memory 106, the measurement start time memory 107, and the cumulative holding time memory 108 are cleared, and the normal duty pressure reducing control start flag 110, the normal duty pressure reducing control holding start flag 114, and Hold time measurement flag 1
15 is reset so that the wheel cylinder pressure is controlled according to the selected control mode.

If the start condition of the special duty pressure reducing control is satisfied a plurality of times and the scheduled execution time of the normal duty pressure reducing control passes during the execution of the special duty pressure reducing control, the determination result of S31 becomes NO, In S36, the termination process of the normal duty pressure reducing control and the special duty pressure reducing control is performed. Duty ratio memory 102,
The pressure reduction time memory 104, the holding time memory 106, the measurement start time memory 107, and the cumulative holding time memory 108 are cleared, and the special duty pressure reduction control start flag 112 and the normal duty pressure reduction control holding start flag 11
4, holding time measurement flag 115 and holding interruption flag 1
16 is reset. Note that S31 is executed when the duty pressure reducing mode is selected in the hydraulic pressure control routine of FIG. 4, and it is said that the holding time exceeds the scheduled holding execution time in the state where the duty pressure reducing mode is selected. This means that the normal duty pressure reducing control is executed again, and the normal duty pressure reducing control start flag 110 is not reset. Then S37
After the duty ratio is determined in the same manner as in S22, a duty reduction control execution routine is performed, and pressure reduction and holding are performed based on the newly determined duty ratio.

Once the start condition of the special duty pressure reducing control is satisfied and the special duty pressure reducing control is started, the pressure reduction and the holding are normally executed for the predetermined times. However, the continuation condition of the special duty pressure reducing control (in the present embodiment, the same as the continuation condition of the special duty pressure reducing control) is satisfied during the execution of the special duty pressure reducing control because of a sudden change in the road surface condition or the like. It may not be done. In this case, the determination result of any of S32 to 34 is NO, S35 is executed to end the special duty pressure reducing control, and the normal duty pressure reducing control is resumed. The special duty pressure reduction control start flag 112 and the hold interruption flag 116 are reset.

As a result, when the determination in S24 is subsequently performed, the determination result is NO, and it is determined whether or not the start condition of the special duty pressure reducing control is satisfied by executing S26 to 28, and it is determined. If so, the special duty pressure reducing control is executed to reduce the wheel cylinder pressure. If the same special duty pressure reduction control continuation condition as the special duty pressure reduction control start condition is satisfied during the execution of S32 to S34, the special duty pressure reduction control is continued, the pressure reduction is performed if the pressure is being reduced, and the holding is maintained if the pressure is being retained. However, after the special duty pressure reducing control continuation condition is once unsatisfied at the time of executing S32 to S34 and the special duty pressure reducing control is ended in S35, the same condition is again satisfied (in this case, the special duty pressure reducing control start condition is set. If (Yes) is satisfied, the determination results of S26 to S28 are all YES, and the pressure reduction of the special duty pressure reduction control is started again. Even if the same condition is satisfied during the same holding execution, the meaning of the condition is different between during the holding execution of the special duty pressure reduction control and during the holding execution of the normal duty pressure reduction control.

When the start condition of the special duty pressure reducing control is satisfied a plurality of times within the holding execution time of the normal duty pressure reducing control and the special duty pressure reducing control is performed a plurality of times,
The depressurization and the holding are performed at the same time. If another control mode is selected during execution of the special duty pressure reduction control, the duty reduction mode is ended, such as resetting the special duty pressure reduction control start flag 112 and the normal duty pressure reduction control start flag 110 when the control mode is executed. Processing is performed.

The relationship among the wheel speed, wheel acceleration and wheel cylinder pressure control modes when antilock control is performed is shown in the graph of FIG. If the start condition of the special duty pressure reducing control is not satisfied within the scheduled holding execution time of the normal duty pressure reducing control, the holding is continued as shown by the solid line in FIG. 7, but if it is satisfied, it is shown by the broken line in FIG. As shown by the thick line in FIG. 8, the special duty pressure reducing control is performed. Therefore, the duty ratio determination map of the normal duty pressure reduction control is set so that the pressure reduction time is shorter than that of the duty ratio determination map for the normal specification vehicle on the side where the road surface friction coefficient is high, and is set for the sports specification vehicle. However, a sufficient feeling of deceleration is usually obtained. If a special situation occurs and the pressure reduction time is insufficient, the special duty pressure reduction control is executed to compensate for the insufficient pressure reduction amount, the wheel slip is quickly recovered, and the normal duty pressure reduction control is performed twice. It is satisfactorily avoided that the braking distance is extended due to the above execution or sudden decompression.

As is apparent from the above description, in the present embodiment, the first and second electromagnetic on-off valves 50, 56, the reservoir 54, the pump 62 and the like constitute a hydraulic pressure control device, and the electronic control unit 90 is provided. The portion that performs the special duty pressure reduction control within the holding execution time of the normal duty pressure reduction control constitutes the holding execution special pressure reduction execution means. Further, a part of the electronic control unit 90 that executes the holding time measuring routine for normal duty pressure reducing control to measure the scheduled holding execution time constitutes the holding execution time measuring means.

Another embodiment of the present invention is shown in FIG. In the present embodiment, the normal pressure reducing control is performed by the duty pressure reducing control as in the above embodiment, but the special pressure reducing control is performed only by the pressure reducing. Therefore, this will be referred to as special simple pressure reducing control in comparison with the special duty pressure reducing control. Of the brake device for a vehicle provided with the antilock control device of this embodiment, and the program for executing the antilock control, the main routine and the hydraulic pressure control routine are configured in the same manner as in the above embodiments, and The description is omitted. Hereinafter, the pressure reduction control will be described based on the pressure reduction control command output routine shown in FIG. 9.

S51 to S53 are executed in the same manner as S21 to 23 of the pressure reducing control command output routine shown in FIG.
If the normal duty pressure reducing control is started, the determination result in S51 is YES, and in S54, it is determined whether or not it is within the scheduled execution time of the normal duty pressure reducing control. Also in this embodiment, the holding time of the normal duty pressure reducing control is measured by the holding time measuring routine for normal duty pressure reducing control as in the case of the above embodiment, and it may be within the scheduled holding execution time obtained by determining the duty ratio. For example, the determination result of S54 is YES, and it is determined in S55 whether or not the holding is being executed. If the holding is not being executed, the determination result of S55 is NO, and the execution of this routine ends.

If the determination result of S55 is YES, S5
At 6 to 58, it is determined whether the special simple pressure reducing control start condition is satisfied. The starting condition of the special simple pressure reducing control is the same as the starting condition of the special duty pressure reducing control, and the special simple pressure reducing control is not performed unless any one of them is satisfied. If all start conditions are satisfied, S5
9 is executed, and the holding interruption command for the normal duty pressure reducing control is output. Computer RA as shown in FIG.
The holding interruption flag 116 provided in M is set. Next, in S60, the special simple decompression control start command is output, that is, the special simple decompression control start flag 130.
Is set and the execution of this routine ends. By setting the special simple pressure reduction control start flag 130, pressure reduction is started.

The decompression time of this special simple decompression control is set to 4 ms, and when the decompression command routine executed every 6 ms is executed next time, the special simple decompression control is completed and the special simple decompression control is started. The flag 130 and the hold interruption flag 116 are reset in the pressure reduction control execution routine. Therefore, the normal duty pressure reducing control is held, and if it is within the scheduled holding execution time, the determination result of S54 is YES, the determination result of S55 is also YES, and it is determined whether the special simple pressure reducing control should be started again. If it is determined and the condition is satisfied, the special simple pressure reducing control is started.

After the pressure reduction of the normal duty pressure reduction control is completed, if the scheduled execution time of the normal duty pressure reduction control elapses, the determination result of S54 becomes NO, and the termination process of the duty pressure reduction is performed in S61. Duty ratio memory 1
02, decompression time memory 104, holding time memory 106,
Measurement start time memory 107, cumulative holding time memory 108
Is cleared, the normal duty pressure reducing control holding start flag 114 and the holding time measuring flag 115 are reset. However, since the duty reduction is selected as the control mode, the normal duty reduction control start flag 110 is not reset. Then, if the duty ratio is determined in S62, the execution of this routine is ended, the duty reduction control execution routine is executed, and the normal duty reduction control is started. Since the normal duty pressure reducing control holding start flag 114 is reset and the normal duty pressure reducing control start flag 110 is set, the pressure reduction time and the holding time are calculated based on the newly determined duty ratio, and the pressure reduction time memory 104 is calculated. , Is stored in the holding time memory 106, and decompression and holding are executed.

As is apparent from the above description, in the present embodiment, when the special simple pressure reducing control start condition is satisfied while the duty reducing pressure control of the electronic control unit 90 is being held, the special simple pressure reducing control is started. The portion constitutes the special decompression executing means during the holding execution.

In the above two embodiments, the main routine, the hydraulic pressure control routine, the pressure reducing control command routine, the normal duty pressure reducing control holding time measuring routine, etc. are all executed in the same cycle time. It is also possible that at least two of these routines have different cycle times. It is also possible to change at least a part of these routines. For example, in the above-described embodiment, the start condition satisfaction determination and the continuation condition satisfaction determination of the special pressure reduction control are performed in the pressure reduction control command routine, but are performed in the interrupt pressure reduction control command routine. It is also possible. This interrupt pressure-reduction control command routine is started, for example, in response to the end of the pressure reduction of the normal duty pressure-reduction control, and the success or failure of the start condition or the continuation condition of the special pressure-reduction control is judged by interruption every certain short time, and then started. The execution of the special pressure reducing control may be instructed by an interrupt when the condition is satisfied and when the continuation condition is not satisfied. With this configuration, the success / failure determination of the special decompression control start condition or continuation condition can be repeatedly executed in a cycle time shorter than the cycle time of the main routine, the decompression control routine, the decompression control command routine, etc. Start and end can be done with less delay. In the above embodiment, the start condition and the continuation condition of the special pressure reduction control were the same,
You can make them different. For example, the continuation condition may be one in which the road acceleration is high and the road surface is a good road, in addition to the wheel acceleration being equal to or less than the set value during execution of holding, Alternatively, the continuation condition may be only that the wheel acceleration is less than or equal to the set value during the holding execution, or the wheel acceleration is less than or equal to the set value during the holding execution, the road surface is a good road, and the road surface friction coefficient. May be set as a continuation condition, and the set value for determining the magnitude of the wheel acceleration may be different from the set value for determining the magnitude of the wheel acceleration under the special decompression control start condition. In the start condition and the continuation condition, the types of elements constituting the condition such as wheel acceleration, road surface condition, road surface friction coefficient, etc. may be different from each other, or different set values may be used.

In the above-described two embodiments, the set acceleration in the start condition of the special pressure reducing control is smaller than the minimum of the plurality of set accelerations in the starting condition of the normal pressure reducing control, but the special pressure reducing control is usually performed. The fact that the wheel pressure is lower than the wheel acceleration at the start of the pressure reducing control can be set as at least one of the special pressure reducing control starting conditions, and the wheel acceleration is negative and the wheel acceleration at the time of starting the normal pressure reducing control is 1 It is also possible to set at least one of the special pressure reduction control start conditions to be smaller than a value obtained by multiplying a larger or smaller positive constant. In addition, in the above-described second embodiment, the three conditions for starting the special pressure reduction control are that the wheel acceleration is equal to or less than the set value during execution of holding, that the road surface is a good road, and that the road surface friction coefficient is high. However, the start condition may be that the wheel acceleration is less than or equal to the set value during holding, and that the road surface friction coefficient is high or the road is good. The starting condition may be that the acceleration becomes equal to or less than the set value. Further, in the above-described two embodiments, the starting condition for the second or subsequent normal pressure reducing control is the same as the starting condition for the first normal pressure reducing control, but it can be different. For example, under the second and subsequent start conditions, the normal pressure reduction control is started in a slip state shallower than the first time by at least one of decreasing the slip ratio and increasing the wheel acceleration (decreasing the wheel deceleration). To do so. In addition to the slip ratio and the wheel acceleration, there are slip amount, slip ratio change rate, vehicle deceleration, and the like as the amount that regulates the slip state, and these are appropriately combined to determine the hydraulic pressure control mode determination conditions (normal duty pressure reduction control). (Including the start condition of) and the start condition and the continuation condition of the special decompression control can be set. Besides, the present invention can be implemented in various modified and improved modes based on the knowledge of those skilled in the art without departing from the scope of the claims.

[Brief description of drawings]

FIG. 1 is a system diagram showing a hydraulic brake device including an antilock control device according to an embodiment of the present invention.

FIG. 2 is a diagram conceptually showing a portion deeply related to the present invention in a RAM of an electronic control unit constituting the antilock control device.

FIG. 3 is a ROM of a computer of the electronic control unit.
3 is a flowchart showing a main routine stored in FIG.

FIG. 4 is a flowchart showing a hydraulic pressure control routine stored in the ROM.

FIG. 5 is a flowchart showing a pressure reduction control command output routine stored in the ROM.

FIG. 6 is a flowchart showing a holding time measuring routine for normal duty pressure reducing control stored in the ROM.

FIG. 7 is a graph showing a relationship among wheel speeds, wheel accelerations, and wheel cylinder pressure control modes when antilock control is performed by the antilock control device.

FIG. 8 is a graph showing a control mode of wheel cylinder pressure when special duty pressure reducing control is performed.

FIG. 9 is a ROM of a computer of an electronic control unit that constitutes an antilock control device according to another embodiment of the present invention.
5 is a flowchart showing a pressure reduction control command output routine stored in FIG.

10 is a flow chart showing a pressure reduction control command output routine shown in FIG.
It is a figure which shows notionally the part deeply related with this invention among the RAMs of the computer stored in M.

[Explanation of symbols]

 20 Left front wheel 22 Wheel cylinder 26 Right rear wheel 28 Wheel cylinder 34 Right front wheel 36 Wheel cylinder 40 Left rear wheel 42 Wheel cylinder 50 First solenoid on-off valve 54 Reservoir 56 Second solenoid on-off valve 62 Pump 90 Electronic control unit

Claims (1)

[Claims] 1. A hydraulic pressure control device for increasing, reducing, and maintaining the hydraulic pressure of a wheel cylinder of a brake for suppressing the rotation of wheels, and controlling the hydraulic pressure control device to reduce the pressure once each. An anti-lock control device including a hydraulic pressure control device control means for performing a normal pressure reduction control consisting of holding to reduce the hydraulic pressure of the wheel cylinder to keep the slip state of the wheel in an appropriate state. When the pressure reduction start condition different from the pressure reduction start condition of the normal pressure reduction control is satisfied during the execution of the holding of the normal pressure reduction control, the control means performs the special pressure reduction for a time shorter than the execution time of the holding that constitutes the normal pressure reduction control. An anti-lock control device comprising special decompression executing means during holding execution.