JP5583656B2 - Brake hydraulic pressure control device for vehicles - Google Patents

Description

  The present invention relates to a vehicular brake hydraulic pressure control device, and more particularly to a vehicular brake hydraulic pressure control device that stabilizes the operation at the start of antilock brake control.

  Conventionally, in order to suppress the lock of the wheel, anti-lock brake (ABS) control for determining that the wheel is about to lock from the wheel speed and reducing the hydraulic pressure of the brake corresponding to the wheel that is likely to be locked is widely used. It has been put into practical use. Further, as a vehicle brake hydraulic pressure control device that controls pressure increase and pressure reduction using a control valve means, as in Patent Document 1, the brake hydraulic pressure on the rear wheel side is limited according to the depression speed of the brake pedal. A configuration of braking force distribution control is disclosed.

Japanese Patent Laid-Open No. 11-180281

  However, when sudden braking is applied, the vehicle load is likely to be applied to the front wheels, so that the hydraulic pressure at which pressure reduction (ABS) control is started in the front wheel brake is increased. For this reason, when the front wheels are about to lock after sudden braking, the amount of pressure reduction until the locked state of the wheels is released increases, and after this pressure reduction, sudden pressure increase is likely to occur, and the initial operation of ABS control is likely to occur. There is a problem that it becomes unstable due to repeated rapid pressure reduction and pressure increase. In other words, there is a problem that the situation becomes similar to the overshoot in the control technology (which greatly exceeds the target value). Such a problem tends to be particularly problematic when adjusting the hydraulic pressure balance of the front and rear wheels by reducing the hydraulic pressure of the rear wheels as in Patent Document 1, since the ratio of using the braking force of the front wheels increases. .

  Therefore, an object of the present invention is to provide a vehicle brake hydraulic pressure control device that stabilizes the operation at the start of antilock brake control.

The present invention that solves the above problems is a normally open proportional solenoid valve provided in a hydraulic pressure path from a hydraulic pressure source to a wheel brake, and a normally closed type provided in a hydraulic pressure path from the wheel brake to the hydraulic pressure source. An anti-lock brake control is performed to control the solenoid valve, the normally open proportional solenoid valve, and the normally closed solenoid valve to increase, reduce or maintain the hydraulic pressure of the wheel brake to suppress the lock of the wheel. A brake hydraulic pressure control device for a vehicle having anti-lock brake control means, comprising: a sudden braking determination means for determining whether or not sudden braking has been performed based on a change amount of wheel speed; The presence or absence of sudden braking is determined based on whether or not the wheel deceleration exceeds a threshold, and the absolute value of the deceleration is determined according to the time from when the absolute value of the wheel deceleration exceeds a predetermined value. change to the large side, the antilock The brake control means, when it is determined that there is a sudden braking by the sudden braking determination means, fully closes the normally open proportional solenoid valve with respect to the wheel brake of the front wheel during the pressure increase by the sudden braking, During the first predetermined time, the holding control is performed, and thereafter, the pressure is increased at a predetermined gradient by flowing a current through the normally open proportional solenoid valve until the pressure reducing control is performed.

According to such a configuration, when it is determined by the rapid braking determination means that the sudden braking has occurred, the normally open proportional solenoid valve is fully closed during the pressure increase due to the sudden braking, and the hydraulic pressure of the front wheel brakes is increased. Is held for a first predetermined time. Due to the temporary holding control by fully closing the normally open proportional solenoid valve, it is possible to reliably stop the flow of the brake fluid from the hydraulic pressure source and perform the subsequent gradually increasing control. Then, after this temporary holding control, the current flowing through the normally open proportional solenoid valve is controlled to limit the brake fluid flowing from the fluid pressure source to the wheel brake side, thereby reducing the fluid pressure of the front wheel brake to a predetermined value. The ABS control can be executed by increasing the pressure with a gradient and searching for the tendency of the wheels to lock. In this way, by suppressing a sudden increase in hydraulic pressure of the front wheel brake during sudden braking, it is possible to reduce fluctuations in the brake hydraulic pressure at the start of ABS control and to stabilize the operation. Further, since the sudden braking determination means determines whether or not sudden braking has been performed based on the amount of change in wheel speed, whether or not sudden braking has been performed without using a sensor or the like that detects the amount of pedal depression is determined. Can be determined. Then, the sudden braking determination means determines whether or not there is sudden braking depending on whether or not the wheel deceleration exceeds a threshold, and according to the time from when the absolute value of the wheel deceleration becomes a predetermined value or more, Since the threshold value is changed to the larger absolute value of the deceleration, it is possible to accurately determine the presence or absence of the sudden braking based on the change in the wheel deceleration.

  In the apparatus described above, the predetermined gradient can be set so as to gradually become steep as time elapses.

  By making the predetermined gradient gradually steep with the passage of time, regardless of the brake fluid pressure of the front wheels when entering temporary retention control (for example, temporary retention control is performed at a low brake fluid pressure). Even if it does, it can make it easy to enter pressure reduction control.

  In the above-described device, the anti-lock brake control means is configured to perform the normally open type when pressure reduction control is not performed even after a second predetermined time has elapsed since the start of pressure increase by the predetermined gradient. It is desirable to fully open the proportional solenoid valve.

  According to such a configuration, when the pressure reduction control is not performed even after the second predetermined time has elapsed since the start of pressure increase by a predetermined gradient, the normally open proportional solenoid valve is fully opened. Even if there is an error in the determination of sudden braking, a normal braking force can be generated.

  According to the vehicle brake hydraulic pressure control device of the present invention, it is possible to reduce the fluctuation of the brake hydraulic pressure at the start of ABS control and stabilize the operation by suppressing the rapid hydraulic pressure increase of the front wheel brake during sudden braking. it can.

1 is a configuration diagram of a vehicle including a vehicle brake hydraulic pressure control device according to an embodiment of the present invention. It is a block diagram which shows the structure of a hydraulic unit. It is a block diagram which shows the structure of a control part. It is a flowchart which shows the process of ABS control. It is a flowchart which shows the process of sudden braking determination. It is a flowchart which shows the process of the control at the time of sudden braking of ABS control. It is an example of the table which shows the relationship between count value TM1 of a threshold value setting timer, and sudden braking determination threshold value WAth2. It is an example of the table which shows the relationship between count value TM2 of a pressure control timer, and a pressure increase gradient. It is a time chart which shows the time change of each parameter of (a) count value TM2, (b) caliper pressure, (c) pressure control state, (d) wheel acceleration, and (e) count value TM1.

Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.
As shown in FIG. 1, the vehicle brake fluid pressure control device 100 is a device that appropriately controls the braking force applied to each wheel T of the vehicle CR. The vehicle brake hydraulic pressure control device 100 includes a hydraulic unit 10 provided with a hydraulic path and various parts, and a control unit 20 as an example of a control unit for appropriately controlling various parts in the hydraulic unit 10. Mainly prepared.

  Each wheel T is provided with a wheel brake FL, RR, RL, FR, and each wheel brake FL, RR, RL, FR is supplied with a hydraulic pressure supplied from a master cylinder M as an example of a hydraulic pressure source. A wheel cylinder W that generates a braking force is provided. The master cylinder M and the wheel cylinder W are each connected to the hydraulic unit 10. The brake hydraulic pressure generated in the master cylinder M in response to the depression force of the brake pedal P (the driver's braking operation) is supplied to the wheel cylinder W after being controlled by the control unit 20 and the hydraulic pressure unit 10. .

  A pressure sensor 91 that detects the hydraulic pressure in the master cylinder M and a wheel speed sensor 92 that detects the wheel speed WV of each wheel T are connected to the control unit 20. The control unit 20 includes, for example, a CPU, a RAM, a ROM, and an input / output circuit. Based on inputs from the pressure sensor 91 and the wheel speed sensor 92, and various programs and data stored in the ROM, By performing arithmetic processing, control for increasing / decreasing the hydraulic pressure of the wheel brakes FL, RR, RL, FR is executed. Details of the control unit 20 will be described later.

  As shown in FIG. 2, the hydraulic unit 10 is disposed between the master cylinder M and the wheel brakes FL, RR, RL, FR. The two output ports M1, M2 of the master cylinder M are connected to the inlet port 10A of the hydraulic unit 10, and the outlet port 10B is connected to each wheel brake FL, RR, RL, FR. In a normal state, the hydraulic pressure path in which the inlet port 10A to the outlet port 10B in the hydraulic pressure unit 10 communicates with each other allows the pedaling force of the brake pedal P to be transmitted to the wheel brakes FL, RR, RL, FR. It has come to be.

  The hydraulic pressure unit 10 is provided with four inlet valves 1, four outlet valves 2, and four check valves 1a corresponding to the wheel brakes FL, RR, RL, FR. Further, two reservoirs 3, two pumps 4, and two orifices 5a are provided corresponding to the respective output hydraulic pressure paths 81, 82 corresponding to the output ports M1, M2, and are electrically driven for driving the two pumps 4. A motor 6 is provided.

The inlet valve 1 is a normally open proportional solenoid valve arranged in a hydraulic pressure path (upstream of each wheel brake FL, RR, RL, FR) from the master cylinder M to each wheel brake FL, RR, RL, FR. is there. The inlet valve 1 is normally open to allow the brake hydraulic pressure to be transmitted from the master cylinder M to the wheel brakes FL, RR, RL, FR. Further, the inlet valve 1 is blocked by the control unit 20 when the wheel T is about to be locked, thereby blocking the hydraulic pressure transmitted from the brake pedal P to each wheel brake FL, RR, RL, FR.
Although not shown in detail, the valve body of the inlet valve 1 is urged toward the master cylinder M by an electromagnetic force corresponding to the applied current, and the liquid of the wheel brakes FL, RR, RL, FR is urged by this urging force. The pressure can be adjusted.

  The outlet valve 2 is located between each wheel brake FL, RR, RL, FR and each reservoir 3 (on the hydraulic pressure path leading from the hydraulic pressure path on the wheel cylinder W side of the inlet valve 1 to the reservoir 3, the pump 4 and the master cylinder M). ) Is a normally closed solenoid valve. Although the outlet valve 2 is normally closed, the hydraulic pressure applied to each wheel brake FL, RR, RL, FR is supplied to each reservoir by being opened by the control unit 20 when the wheel T is likely to be locked. Escape to 3.

  The check valve 1a is connected to each inlet valve 1 in parallel. This check valve 1a is a valve that allows only the flow of brake fluid from each wheel brake FL, RR, RL, FR side to the master cylinder M side, and an inlet valve when the input from the brake pedal P is released. Even when 1 is closed, the flow of brake fluid from each wheel brake FL, RR, RL, FR side to the master cylinder M side is allowed.

The reservoir 3 has a function of absorbing brake fluid that is released when each outlet valve 2 is opened.
The pump 4 has a function of sucking the brake fluid absorbed in the reservoir 3 and returning the brake fluid to the master cylinder M through the orifice 5a. As a result, the pressure state of each of the output hydraulic pressure paths 81 and 82 reduced by the absorption of the brake hydraulic pressure by the reservoir 3 is recovered.

  The opening and closing states of the inlet valve 1 and the outlet valve 2 are controlled by the control unit 20 so that the hydraulic pressure in the wheel cylinder W of each wheel brake FL, RR, RL, FR (hereinafter also referred to as “caliper pressure”). To control. For example, in a normal state in which the inlet valve 1 is open and the outlet valve 2 is closed, if the brake pedal P is depressed, the hydraulic pressure from the master cylinder M is transmitted to the wheel cylinder W as it is to increase the pressure. When the valve 1 is closed and the outlet valve 2 is opened, the brake fluid flows out from the wheel cylinder W to the reservoir 3 side so that the pressure is reduced. When both the inlet valve 1 and the outlet valve 2 are closed, the caliper pressure is maintained. Will be held. In addition, when the hydraulic pressure of the master cylinder M is rising, if an appropriate current that does not reach the full closing state is supplied to the inlet valve 1 with the outlet valve 2 closed, the master cylinder M is set according to the current. Inflow of brake fluid into the wheel cylinder W is restricted, and the hydraulic pressure in the wheel cylinder W can be gradually increased.

  Next, details of the control unit 20 will be described. As shown in FIG. 3, the control unit 20 receives the master cylinder pressure PM from the pressure sensor 91 and the wheel speed WV from the wheel speed sensor 92, and the inlet valve 1 and the outlet valve 2 based on at least the wheel speed WV. To control. The control unit 20 includes an antilock brake control unit 110, a sudden braking determination unit 120, a valve drive unit 140, and a storage unit 180.

  The antilock brake control means 110 includes a slip ratio calculation unit 111 and a pressure control determination unit 112.

  The slip ratio calculation unit 111 has a function of calculating the slip ratio SL of each wheel T based on the output from the wheel speed sensor 92 by a known calculation method and outputting it to the pressure control determination unit 112. For example, the slip ratio SL can be obtained by dividing the difference (slip amount) between the vehicle body speed estimated from the wheel speed WV and the wheel speed WV by the wheel speed WV.

  The pressure control determination unit 112 increases the brake fluid pressure (caliper pressure) of each wheel T in a reduced state based on the wheel acceleration WA and the slip rate SL estimated from the wheel speed WV as in a known ABS control device. It has a function of determining whether to be in a pressure state or a holding state and outputting it to the valve drive unit 140. That is, when the slip ratio SL is larger than the predetermined threshold SLth and the wheel acceleration WA is 0 or less (wheel deceleration is 0 or more), it is determined that the wheel T is likely to be locked, and the caliper pressure is reduced. Decide what to do. Further, when the wheel acceleration WA is larger than 0, it is determined that the caliper pressure is held, and when the slip rate SL is equal to or smaller than a predetermined threshold and the wheel acceleration WA is equal to or smaller than 0, the caliper pressure is determined. Is determined to be in a pressure increasing state. In the present embodiment, the wheel acceleration and the wheel deceleration are handled by one parameter (wheel acceleration WA). When the wheel acceleration WA is negative, it can be seen that the wheel is decelerating.

  In addition to such general ABS control, the pressure control determination unit 112, in the present embodiment, in order to stabilize the operation during sudden braking, the temporary holding control unit 112A, the gradually increasing pressure control unit 112B, And a pressure control timer 112C.

  The temporary holding control unit 112A fully closes the inlet valve 1 corresponding to the wheel brakes FR and FL of the front wheels during the pressure increase by the sudden braking when the sudden braking determination unit 120 determines that there is sudden braking. 1 for a predetermined time (a time corresponding to a threshold value TM2th1 described later). This temporary holding control is for surely stopping the flow of the brake fluid flowing from the master cylinder M to the front wheel brakes FR and FL during sudden braking, and performing the subsequent incremental pressure control with certainty. Therefore, the current that flows through the inlet valve 1 is sufficient if it is sufficient to close the inlet valve 1, and the current can be simply flowed at a duty ratio of 100%, but as long as the inlet valve 1 can be closed, The duty ratio is not necessarily limited to 100%. The first predetermined time for closing the inlet valve 1 is sufficient if the inlet valve 1 can be closed once. Therefore, a time as short as possible is longer than the response time of the inlet valve 1. It is set accordingly. In the present embodiment, the temporary holding control unit 112A determines the predetermined time based on whether or not the count value TM2 of the pressure control timer 112C exceeds the threshold value TM2th1.

  The gradual pressure increase control unit 112B has a function of controlling the current flowing through the inlet valve 1 and increasing the pressure with a predetermined gradient immediately after the temporary holding control by the temporary holding control unit 112A. This gradually increasing pressure is performed until the pressure reducing condition (WA ≦ 0 and SL> SLth) in the basic ABS control of the pressure control determination unit 112 is satisfied. The predetermined gradient here is obtained by restricting the brake fluid flowing in from the master cylinder M by slightly closing the inlet valve 1, so that the inlet valve 1 is temporarily opened (no current flows). ), The slope is small. The current that flows through the inlet valve 1 to increase the pressure gradually may be a constant value, or the pressures of the wheel brakes FR and FL are predetermined while comparing the pressure of the master cylinder M and the pressure of the wheel brakes FR and FL. The current may be changed so as to increase at a slope of. When the current flowing through the inlet valve 1 is constant, the predetermined gradient is not necessarily constant, and when the current is changed as in the latter, the gradient is constant (as a target).

  Furthermore, as a more desirable form, the gradual pressure increase control unit 112B can set the pressure increase gradient to be gradually larger (steep) in accordance with the count value TM2 of the pressure control timer 112C. For example, as shown in FIG. 8, the pressure increase gradient may be a constant value as indicated by a solid line, or may gradually increase as TM2 increases as indicated by a broken line. When the pressure increase gradient is gradually increased, a certain value (upper limit value) may be obtained after a certain time has elapsed as indicated by a broken line in FIG.

  When the count value TM2 of the pressure control timer 112C exceeds the predetermined value TM2th2, that is, the second predetermined time (time corresponding to TM2th2-TM2th1) has elapsed from the start of the gradual pressure control. Even when the pressure reduction control is not performed, the function of stopping the gradually increasing pressure and fully opening the inlet valve 1 is provided. This makes it possible to return to normal ABS control even in the event of an abnormal situation, such as when a sudden braking decision is made.

  The pressure control timer 112 </ b> C is a timer that counts the time after the sudden braking determination unit 120 determines sudden braking. Based on the count value TM2 of the pressure control timer 112C, the time for the temporary holding control and the time for the gradually increasing pressure can be monitored.

  In the present embodiment, the temporary holding control and the gradual pressure increase control are intended only for the front wheels. This is because, when sudden braking is performed, the load on the front wheels increases while the load on the rear wheels decreases, so that at the initial stage of braking, the braking control of the front wheels has a great influence on the stability of the vehicle.

  The sudden braking determination means 120 is a means for determining the presence or absence of sudden braking based on the amount of change in the wheel speed WV. Specifically, the sudden braking determination means 120 determines whether or not there is sudden braking depending on whether or not the absolute value of wheel acceleration | WA | (that is, the absolute value of wheel deceleration) exceeds the sudden braking determination threshold WAth2. For this purpose, a threshold setting timer 121 and a threshold setting unit 122 are provided.

  The threshold setting timer 121 has a function of counting the time from when the absolute value of wheel acceleration | WA | (that is, the absolute value of wheel deceleration) becomes equal to or greater than a predetermined value WAth1. During deceleration, since the wheel acceleration decreases as it fluctuates up and down, only the pure deceleration tendency is reflected in the sudden braking determination threshold value WAth2. Therefore, the count value TM1 is calculated while the wheel acceleration is decreasing ( It counts only while the absolute value of wheel deceleration is increasing.

  The threshold setting unit 122 is a means for setting the sudden braking determination threshold WAth2. Specifically, the threshold setting unit 122 sets the sudden braking determination threshold WAth2 with reference to the table of FIG. 7 according to the count value TM1 of the threshold setting timer 121. As shown in FIG. 7, the table for determining the sudden braking determination threshold value WAth2 decreases stepwise as TM1 increases (the absolute value since the wheel T is decelerating when the wheel acceleration WA is negative). Is large). As a result, the sudden braking determination threshold value WAth2 is changed to the larger absolute value of deceleration according to the time (count value TM1) from the time when the absolute value of wheel deceleration becomes equal to or greater than the predetermined value WAth1. It has become.

  The valve driving unit 140 has a function of outputting a control signal to the inlet valve 1 and the outlet valve 2 in accordance with an instruction for pressure reduction, pressure increase, gradual pressure increase or maintenance output from the pressure control determination unit 112. That is, as described above, the inlet valve 1 is closed and the outlet valve 2 is opened in order to reduce the pressure, and the inlet valve 1 is closed and the outlet valve 2 is closed in order to increase the pressure. In order to restrict the flow from the master cylinder M to the front wheel brakes FR and FL by flowing an appropriate current to the inlet valve 1, and to close the outlet valve 2 and hold it, the inlet valve 1 The outlet valves 2 are closed together.

  The storage unit 180 stores threshold values and tables for the above-described controls.

The process of pressure reduction control by the vehicle brake hydraulic pressure control device 100 configured as described above will be described with reference to FIGS.
First, the overall processing of ABS control will be described with reference to FIG. During braking of the vehicle CR, the anti-lock brake control means 110 acquires the wheel speed WV from the wheel speed sensor 92 (S1), and calculates the slip ratio SL from the wheel speed WV (S2). Then, the sudden braking determination means 120 determines the presence or absence of sudden braking (S100). The details of the sudden braking determination process will be described later. If the sudden braking is determined, the sudden braking flag is turned on. If not, the sudden braking flag is turned off. In step S3, the sudden braking determination means 120 determines whether or not the sudden braking flag is ON. When it is determined that sudden braking has been performed and the sudden braking flag is ON (S3, Yes), control during sudden braking (S200) is performed. On the other hand, if the sudden braking flag is OFF (S3, No), it is determined whether the wheel acceleration WA is 0 or less. If not (S4, No), the inlet valve 1 is fully closed to hold control. (S8). When the wheel acceleration WA is equal to or less than 0 (S4, Yes), it is determined whether the slip ratio SL is larger than the threshold value SLth. When the slip rate SL is larger (S5, Yes), the outlet valve 2 is opened and pressure reduction control is performed (S6). ), If not large (S5, No), the inlet valve 1 is fully opened and pressure increase control is performed (S7).

  In the ABS control described above, the sudden braking determination process will be described. As shown in FIG. 5, first, the threshold setting timer 121 determines the absolute value of the wheel acceleration in order to determine whether or not to increment the count value TM1. It is determined whether the value | WA | (absolute value of wheel deceleration) is equal to or greater than a predetermined value WAth1. Here, since wheel acceleration WA is a variable, it is determined whether WA is negative and the absolute value of WA is equal to or greater than WAth1 (S101). If these two conditions are satisfied (S101, Yes), it is further determined whether dWA / dt is negative in order to determine whether the wheel acceleration WA is decreasing (S102). When dWA / dt is negative (S102, Yes), the count value TM1 is incremented (S103), and the process proceeds to step S104. When dWA / dt is not negative (S102, No) and when the condition of step S101 is not satisfied, the process proceeds to step S104 without incrementing the count value TM1. Then, the threshold setting unit 122 sets the sudden braking determination threshold WAth2 according to the table of FIG. 7 according to the count value TM1 (S104). Then, the sudden braking determination means 120 determines whether the wheel acceleration WA is smaller than the sudden braking determination threshold WAth2 (whether the wheel deceleration exceeds the threshold), and if the wheel acceleration WA is smaller than the sudden braking determination threshold WAth2 ( (S105, Yes), it is determined that sudden braking has been performed, and the sudden braking flag is turned ON (S107). On the other hand, when the wheel acceleration WA is not smaller than the sudden braking determination threshold value WAth2 (S105, No), it is determined that the sudden braking is not performed (S106).

Next, the process for the sudden braking control in step S200 will be described.
As shown in FIG. 6, in step S201, the pressure control determination unit 112 determines whether or not a pressure reducing condition is satisfied as a condition determination for exiting the sudden braking control (S201). This determination is the same as the pressure reduction determination of normal ABS control, and corresponds to step S4 and step S5 in FIG. That is, it is determined whether the wheel acceleration WA is 0 or less and the slip rate SL is larger than the threshold value SLth. If it is determined that the decompression condition is satisfied (S201, Yes), the purpose of the sudden braking control has been fulfilled, so the sudden braking flag is turned off (S202), the decompression is instructed, and the valve drive unit 140 opens the outlet valve 2. Pressure reduction control is performed (S203).

  When the pressure reducing condition is not satisfied in step S201 (S201, No), the pressure control timer 112C increments the count value TM2 as the time during which the sudden braking control is performed (S204). Then, the gradually increasing pressure control unit 112B determines whether or not the count value TM2 is greater than a predetermined value TM2th2. Since the count value TM2 is small when it has just entered the sudden braking control, it does not exceed the predetermined value TM2th2 (S205, No), and the process proceeds to step S206. In step S206, the pressure control determination unit 112 determines whether the count value TM2 is greater than the threshold value TM2th1. Since the count value TM2 is small when it has just entered sudden braking, it is not greater than the threshold value TM2th1 (S206, No), and the holding control is performed by the temporary holding control unit 112A (S207). That is, holding is instructed to the valve driving unit 140, and the inlet valve 1 is fully closed.

  When the time of TM2th1 has elapsed after entering the sudden braking control, it is determined in step S206 that the count value TM2 is greater than TM2th1, and the gradually increasing pressure control unit 112B performs gradually increasing pressure control (S208). That is, when a predetermined current that does not reach the fully closed state flows through the inlet valve 1, the brake fluid from the master cylinder M is restricted from flowing to the front wheel brakes FR and FL, and the incremental pressure control is not performed. Compared to the above, the brake fluid pressure of the front wheel brakes FR, FL gradually increases. When the brake fluid pressure of the front wheel brakes FR and FL increases and the slip ratio SL increases, it is determined in step S201 that the pressure reducing condition is satisfied, the sudden braking flag is turned OFF (S202), and normal The pressure reduction control (S203) is entered.

  After entering the control at the time of sudden braking, when the gradually increasing pressure in step S208 continues to be satisfied and the pressure reducing condition is not satisfied, the gradually increasing pressure control unit 112B determines that the count value TM2 becomes larger than the predetermined value TM2th2 (S205, Yes), the flow of current to the inlet valve 1 is stopped, the inlet valve 1 is opened (S209), the sudden braking flag is turned off (S210), and the sudden braking control is terminated.

  An example of the behavior of the vehicle CR by the above processing will be described with reference to FIG. In FIG. 9, the wheel acceleration WA chart and the TM1 chart show the time axis in an enlarged manner (see the position of t3).

  When sudden braking is performed, the caliper pressure rapidly increases as shown in the caliper pressure chart in FIG. Then, the vehicle CR suddenly decelerates and the wheel acceleration WA (negative value) decreases (the absolute value of the wheel deceleration increases). When the wheel acceleration WA becomes equal to or less than the predetermined value WAth1, (t1), the count value TM1 is counted as shown in (e) (t1 to t5), and the sudden braking determination threshold value WAth2 is set according to the value of the count value TM1. (See t1, t2, t4, (d)). When the wheel acceleration WA falls below the sudden braking determination threshold value WAth2 at time t3, sudden braking is determined and temporary holding control is performed (see t3 to t6 in (b) and (c)).

  After the temporary holding control, when the time corresponding to the threshold value TM2th1 has elapsed since the sudden braking was determined (see t6, (a)), the gradually increasing pressure control is performed (t6 to t7 in (b) and (c). reference). Then, by satisfying the depressurization condition, depressurization is performed (t7 to t8 in (b) and (c)). Thereafter, similarly to the normal ABS control, the pressure is maintained according to the wheel acceleration WA and the slip rate SL (t8 to t9 in (b) and (c)), and the pressure is increased (t9 to t10 in (b) and (c). ) And brake pressure control continues. In addition, from time t9 to t10, the pressure increase control is performed in two stages, but the pressure increase may be performed in one stage.

  As described above as a modified example, when the pressure increase gradient is increased in accordance with the increase in the count value TM2, as shown by the broken line in the caliper pressure chart in FIG. Since the pressure increasing gradient gradually becomes steeper in FIG. 3, even if the brake fluid pressure of the front wheels when entering the temporary holding control is low, it is possible to easily enter the pressure reducing control.

  When temporary holding control and gradual pressure increase control are not performed as in this embodiment, as shown by the two-dot chain line in the caliper pressure chart, the brake pressure rises excessively and excessive slip occurs. If the pressure is not reduced excessively, the slip will not be eliminated, and the change in the caliper pressure becomes very large. On the other hand, when the temporary holding control and the gradual pressure reduction control are performed as in the present embodiment, as shown by the solid line in the caliper pressure chart, an excessive increase in the brake fluid pressure is suppressed, and even in the subsequent pressure reduction, Slip can be eliminated with minimal pressure reduction. In this way, in the vehicle brake hydraulic pressure control apparatus 100 of the present embodiment, the fluctuation of the brake hydraulic pressure at the start of the ABS control can be reduced, and the ABS control and the operation of the vehicle CR can be stabilized.

  In the vehicular brake hydraulic pressure control device 100 according to the present embodiment, the inlet valve 1 is set when the pressure reducing control condition is not satisfied even after the second predetermined time has elapsed since the gradual pressure increasing control is started. Since the pressure is increased with the valve fully opened, even if there is an error in the determination of sudden braking, a normal braking force can be generated.

  Further, in the vehicle brake hydraulic pressure control device 100 of the present embodiment, it is determined whether or not sudden braking has been performed based on the change amount of the wheel speed WV (wheel acceleration WA), and therefore, the pedal depression amount is detected. It is possible to determine whether or not sudden braking has been performed without using a sensor or the like.

  Further, the sudden braking determination means 120 changes the sudden braking determination threshold WAth2 to the larger absolute value of the deceleration according to the time from the time when the absolute value of the wheel deceleration becomes equal to or greater than the predetermined value WAth1. The presence or absence of sudden braking can be accurately determined.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment and can be appropriately modified and implemented.
For example, in the above-described embodiment, the sudden braking determination threshold value WAth2 is decreased stepwise (the absolute value is increased), but may be decreased gradually (continuously).
In the above embodiment, the temporary holding control and the gradual pressure reduction control are performed only for the front wheels. However, the temporary holding control and the gradual pressure reduction control may be performed for the rear wheels in the same manner.

  In the above embodiment, for the sake of simplicity, the vehicle brake hydraulic pressure control device that performs only ABS control is illustrated. However, a control valve is appropriately added to control the vehicle posture, brake assist control, etc. These controls may be combined.

  Further, the sudden braking determination can be performed by using another known method regardless of the method of the embodiment.

DESCRIPTION OF SYMBOLS 1 Inlet valve 2 Outlet valve 10 Hydraulic pressure unit 20 Control part 92 Wheel speed sensor 100 Vehicle brake hydraulic pressure control apparatus 110 Anti-lock brake control means 111 Slip rate calculating part 112 Pressure control determination part 112A Temporary holding control part 112B Gradually increasing pressure control Part 112C Pressure control timer 120 Rapid braking determination means 121 Threshold setting timer 122 Threshold setting part 140 Valve drive part 180 Storage part CR Vehicle FL Wheel brake FR Wheel brake

Claims (3)

A normally open proportional solenoid valve provided in the hydraulic pressure path from the hydraulic pressure source to the wheel brake, a normally closed solenoid valve provided in the hydraulic pressure path from the wheel brake to the hydraulic pressure source, and the normally open proportional solenoid valve Vehicle having anti-lock brake control means for controlling solenoid valve and anti-lock brake control for controlling wheel lock by increasing, depressurizing or maintaining hydraulic pressure of wheel brake by controlling said normally closed solenoid valve Brake fluid pressure control device,
Rapid braking determination means for determining whether or not rapid braking has been performed based on the amount of change in wheel speed ,
The sudden braking determination means determines whether or not sudden braking is performed based on whether or not the wheel deceleration exceeds a threshold value, and sets the threshold value according to a time from when the absolute value of the wheel deceleration becomes a predetermined value or more. Change the deceleration to a larger absolute value,
The anti-lock brake control means fully closes the normally open proportional solenoid valve with respect to the wheel brake of the front wheel during the pressure increase by the sudden braking when the sudden braking determination means determines that there is sudden braking. Then, the vehicle brake fluid is characterized in that the holding control is performed for a first predetermined time and thereafter the pressure is increased at a predetermined gradient by supplying a current to the normally open proportional solenoid valve until the pressure reducing control is performed. Pressure control device.   The vehicular brake hydraulic pressure control apparatus according to claim 1, wherein the predetermined gradient is set so as to gradually become a steep gradient as time elapses. The antilock brake control means includes:
2. The normally open proportional solenoid valve is fully opened when pressure reduction control is not performed even after a second predetermined time has elapsed since the start of pressure increase by the predetermined gradient. Alternatively, the vehicle brake hydraulic pressure control device according to claim 2.

Images