JP2007099274A - Brake control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accomplish the reduction of power consumption and heat generation without deteriorating control quality in a brake control device. <P>SOLUTION: The brake control device is provided with a liquid pressure adjustment means having a solenoid valve for closing a valve so as to seal a brake liquid in a wheel cylinder; a brake control means by executing braking control for generating a desired braking force by increasing pressure, retention and pressure reduction by outputting a control signal toward the liquid pressure adjustment means according to the traveling state of the vehicle detected by a traveling state detection means. When the maximum pressure increase operation of the liquid pressure adjustment means is performed, the braking control means outputs a predetermined duty ratio control signal lower than a maximum duty ratio to the solenoid valve. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention has a hydraulic pressure source other than the master cylinder that mechanically generates pressure according to the operation of the driver, and supplies the hydraulic pressure of the hydraulic pressure source to the wheel cylinder to increase the pressure, The present invention relates to a brake control device that automatically controls a braking force by maintaining the hydraulic pressure of a wheel cylinder or by reducing the hydraulic pressure of the wheel cylinder to another.

  In recent years, various brake control devices that control braking force have been proposed. The control in such a brake control device includes automatic braking control that automatically performs braking according to the distance between the vehicle and the opposite obstacle such as a preceding vehicle, or when an overundersteer state or overoversteer state occurs during a turn. In addition, the vehicle behavior that stabilizes the vehicle behavior by generating the yaw moment that returns the vehicle to the neutral steer direction by automatically controlling the wheel cylinder hydraulic pressure of the front wheel outside the turn and the rear wheel inside the turn to generate the braking force Control, torque slip control that suppresses slip by applying braking force to the drive wheel when the drive wheel slips, and by-wire control that detects braking operation by the driver and generates hydraulic pressure based on this detection value In addition, assist control that assists the braking operation by further increasing the brake fluid pressure generated by the braking operation by the driver. There is.

In the various braking controls described above, control quality is improved so that the driver does not feel uncomfortable. As a technique for improving the control quality of the braking control as described above, for example, one described in Patent Document 1 is known. This conventional technique is a brake control device that automatically performs braking based on the distance between obstacles such as a preceding vehicle. The purpose is to achieve both the prevention and the rapid braking reliably during emergency braking. In order to achieve this object, in this prior art, first, the control deviation is obtained, and based on this control deviation, the proportional control gain is increased when the deviation is large, while the proportional control gain is decreased when the deviation is small. did. Therefore, when the control deviation is small, the hydraulic gradient becomes gentle and “cuckling braking” can be prevented. On the other hand, when braking is urgent, that is, when the control deviation is large, the hydraulic gradient becomes steep and has high responsiveness. Braking is possible, and the above object can be achieved.
JP-A-8-150909.

  However, in the above-described prior art, a signal having a constant duty ratio is always output as a control signal output to the solenoid valve when the hydraulic pressure is maintained. For this reason, there has been a problem that, when holding the hydraulic pressure for a long time, the battery power consumption is increased, and the heat generation amount is increased, which is disadvantageous in terms of durability. In particular, in recent years, the number of in-vehicle electrical equipment has increased, and it is desired to reduce power consumption.

  The present invention has been made paying attention to the above-described conventional problems, and aims to reduce power consumption and heat generation without reducing control quality in a brake control device.

  In order to achieve the above object, the present invention is capable of arbitrarily adjusting the wheel cylinder pressure by increasing / holding / depressurizing the wheel cylinder, and at least maintaining the wheel cylinder pressure. The hydraulic pressure adjusting means having an electromagnetic valve for closing the brake fluid, the traveling state detecting means for detecting the traveling state of the vehicle, and the liquid according to the traveling state of the vehicle detected by the traveling state detecting means. Brake control device comprising: a brake control unit that outputs a control signal to a pressure adjusting unit to execute pressure increase / hold / depressurization and generate a desired braking force. The means outputs a control signal for maintaining the solenoid valve in a closed state when the hydraulic pressure adjusting means is operated to be held, and the control signal indicates the wheel cylinder pressure to be held. Depending wheel cylinder pressure is a means which is a signal for changing to a higher value to execute the current value to be output to the higher solenoid valve.

  According to a second aspect of the present invention, in the brake control device according to the first aspect, the traveling state detecting means is provided with an actual pressure detecting means for obtaining an actual pressure of the wheel cylinder, and the braking control means A target hydraulic pressure calculating means for calculating a target hydraulic pressure of the wheel cylinder based on an input from the detecting means; and an actual wheel cylinder pressure detected by the actual pressure detecting means during the braking control is determined by the target hydraulic pressure calculating means. The hydraulic pressure adjusting means is actuated so as to approach the calculated target hydraulic pressure.

  The invention according to claim 3 is the brake control device according to claim 2, wherein the actual pressure detecting means is means for calculating an actual wheel cylinder pressure based on a vehicle deceleration.

  According to a fourth aspect of the present invention, in the brake control device according to any one of the first to third aspects, the braking control executed by the braking control means obtains an inter-vehicle distance from a preceding vehicle by an input from the traveling state detecting means. The automatic braking control is characterized in that the braking force is generated so that the inter-vehicle distance becomes an optimum value.

  According to a fifth aspect of the present invention, in the brake control device according to the first to fourth aspects, the brake circuit is connected to the wheel cylinder and supplies brake fluid to the wheel cylinder, and the brake fluid is supplied toward the brake circuit. The solenoid valve is a normally open solenoid valve that is connected to a brake circuit and allows the brake fluid in the wheel cylinder to escape to a relatively low pressure circuit on the low pressure side, and the braking control means During braking control, brake fluid is supplied from the hydraulic pressure source to the brake circuit when the pressure is increased, and the electromagnetic valve is temporarily or continuously closed when the pressure is reduced, and supply of the brake fluid from the hydraulic pressure source is stopped when the pressure is maintained. And the electromagnetic valve is closed.

  In the present invention, when the braking control means performs the braking control, when the wheel cylinder pressure is maintained, a control signal, for example, a duty ratio signal for maintaining the valve closed state is output toward the electromagnetic valve. At this time, the control signal controls the execution current value (duty ratio) to be high if the holding pressure is high and the execution current value (duty ratio) to be low if the holding pressure is low, according to the wheel cylinder pressure to be held. Therefore, the control signal output to the solenoid valve can be a control signal having a minimum execution current value (duty ratio) that can keep the solenoid valve closed against the holding pressure. While reducing power consumption and heat generation in the valve and improving durability, it is possible to reliably maintain the valve closed state and maintain control quality.

  In the second aspect of the present invention, the braking control means calculates the target hydraulic pressure based on the input from the running state detection means when executing the braking control, and sets the actual hydraulic cylinder pressure close to the target hydraulic pressure. Activating the pressure adjusting means. In the control of the hydraulic pressure adjusting means, when the actual wheel cylinder pressure approaches the target hydraulic pressure, a control signal of an execution current value (duty ratio) corresponding to the actual wheel cylinder pressure to the solenoid valve to maintain the wheel cylinder pressure. Is output. Therefore, highly accurate braking control according to the control request can be executed.

In the invention according to claim 3, the actual wheel cylinder pressure is calculated based on the vehicle deceleration. That is, the braking force and the vehicle deceleration are correlated, and the actual wheel cylinder pressure can be obtained from the vehicle deceleration. Further, the vehicle deceleration can be obtained from a change in the vehicle body speed obtained from the vehicle body speed from the wheel speed. As an example, the current vehicle speed is Vn, the vehicle speed in the past once (meaning at the time of execution of the previous control routine, for example, 10 msec before) is (Vn-1), and the vehicle speed three times before. Is (Vn−3), the vehicle speed (Vn−4) four times before, deceleration G = [Vn + (Vn−1)] − [(Vn−3) + (Vn−4)]
It can ask for.

  In the invention according to claim 4, the electromagnetic valve of the hydraulic pressure adjusting means is controlled at the time of automatic braking control that keeps the distance between the vehicle and the preceding vehicle optimal, and the brake control that executes such automatic braking control. In the apparatus, it is possible to obtain the effect that the above-described power consumption can be reduced and the durability can be improved. In the invention according to claim 5, at the time of braking control including automatic braking control, the brake fluid is supplied from the fluid pressure source to the brake circuit to increase the pressure of the wheel cylinder, and the electromagnetic valve is opened. Then, the brake fluid in the brake circuit is released to the low pressure side to reduce the pressure. When holding, the supply from the hydraulic pressure source is stopped and the solenoid valve is closed.

  Embodiments of the present invention will be described below with reference to the drawings.

  The first embodiment is an example corresponding to the invention described in claims 1 to 5, and FIG. 1 is a brake circuit diagram showing the brake device of the first embodiment. In the figure, MC is a master cylinder, which is a known cylinder that supplies brake fluid to the wheel cylinder WC via the brake circuits 1 and 2 when the brake pedal BP is depressed. The master cylinder MC is provided with a reservoir RES that stores brake fluid.

  The brake circuits 1 and 2 have a connection structure called so-called X piping. That is, the brake circuit 1 connects the wheel cylinder WC (FL) of the left front wheel and the wheel cylinder WC (RR) of the right rear wheel, and the brake circuit 2 connects the wheel cylinder WC (FR) of the right front wheel and the left rear wheel. The wheel cylinder WC (RL) is connected.

  In the middle of the brake circuits 1 and 2, an out-side gate valve 3 is provided as an electromagnetic valve of the embodiment. The out-side gate valve 3 is a normally open solenoid valve that switches between connection and disconnection of the brake circuits 1 and 2.

  In parallel with the out-side gate valve 3 is a one-way valve 3a that allows only the flow of brake fluid from the master cylinder MC side (hereinafter referred to as upstream) to the wheel cylinder WC side (hereinafter referred to as downstream). Is provided.

  In addition, in the brake circuits 1 and 2, an inflow valve 5 comprising a solenoid-driven normally open ON / OFF valve is provided downstream of the out-side gate valve 3. In the middle of the return circuit 10 linking to 7, an outflow valve 6 composed of a solenoid-driven normally closed ON / OFF valve is provided.

  Further, a pump 4 is connected to the brake circuits 1 and 2 as a hydraulic pressure source other than the master cylinder MC (corresponding to a hydraulic pressure source according to claim 5). The pump 4 serves as a brake fluid pressure source when the driver is not performing a braking operation, and also serves as a return pump when the ABS control is executed.

  The pump 4 is a plunger pump that is operated by a motor 8. The pump 4 includes two plungers 4p and 4p, and a suction chamber in which a pump chamber 4r that performs suction and discharge by the plungers 4p and 4p is branched. The brake circuits 1 and 2 are connected to a position upstream of the out-side gate valve 3 and the reservoir 7 via 4a and 4b. On the other hand, the discharge circuit 4 c is connected to a position between the out-side gate valve 3 and the inflow valve 5 in the brake circuits 1 and 2.

  The suction circuit 4b is provided with a check valve 4d for preventing the brake fluid from flowing in the direction of the reservoir 7. The inflow valve 5, the outflow valve 6, the reservoir 7, the return circuit 10, and the suction circuit 4b constitute an ABS unit. When a wheel lock is likely to occur during braking, the inflow valve 5 is used as necessary. Is closed and the outflow valve 6 is opened to depressurize the wheel cylinder WC, both the inflow valve 5 and the outflow valve 6 are closed to maintain the hydraulic pressure of the wheel cylinder WC, or the inflow valve 5 is opened. At the same time, the outflow valve 6 can be closed to increase the pressure.

  The suction circuit 4a is provided with an in-side gate valve 9 for switching communication / blockage of the suction circuit 4a. The in-side gate valve 9 is a normally closed solenoid valve.

  The operations of the two gate valves 3, 9, the inflow valve 5, the outflow valve 6 and the motor 8 are controlled by a control unit 11 as a braking control means. As shown in FIG. 2, the control unit 11 includes a wheel speed sensor 12 and is connected to a traveling state detection unit 13 that detects the traveling state of the vehicle. The control unit 11 will be described later based on an input from the traveling state detection unit 13. ABS control and automatic braking control are executed. Incidentally, the driving state detection means 13 includes means for detecting the driving operation state of the driver, that is, the braking operation, the steering, and the accelerator operation.

  The ABS control is a well-known control. In brief, in this embodiment, the wheel lock at the time of braking is determined based on the input from the wheel speed sensor 12, and the wheel is likely to be locked. After the wheel cylinder pressure is reduced to avoid wheel lock, the wheel speed of the target wheel is appropriately reduced, held, and adjusted so that the wheel speed is lower than the vehicle speed by a predetermined value and is the most effective speed for braking. The pressure is increased.

  The pressure reduction / holding / pressure increase in the ABS control is performed by closing the inflow valve 5 and opening the outflow valve 6 in the case of pressure reduction, and closing both valves 5 and 6 in the case of holding. In this case, the inflow valve 5 is opened and the outflow valve 6 is closed. During decompression, the brake fluid in the wheel cylinder WC is released to the reservoir 7. The brake fluid accumulated in the reservoir 7 is returned to the brake circuits 1 and 2 as needed based on the operation of the pump 4.

  In this embodiment, automatic braking control is executed. This automatic braking control detects a traveling state based on an input from the traveling state detection means 13 and automatically generates a braking force. For example, the inter-vehicle distance is detected from the preceding vehicle. Includes a control for automatically generating a braking force when the vehicle speed is shorter than the ideal inter-vehicle distance corresponding to the vehicle speed and maintaining the inter-vehicle distance at the ideal inter-vehicle distance.

  When executing the above-described automatic braking control, the in-side gate valve 9 is opened and the pump 4 is operated to discharge the brake fluid to the brake circuits 1 and 2. At this time, if the inflow valve 5 and the outflow valve 6 are deactivated, the inflow valve 5 is kept open, and the outflow valve 6 is kept closed, the wheel cylinder pressure is increased.

  In this embodiment, as will be described later, the amount of pressure increase is controlled by performing pulse modulation control (hereinafter referred to as PWM control) on the motor 8 (pump 4). On the other hand, when the out-side gate valve 3 is opened from this state, the brake fluid in the brake circuits 1 and 2 is released to the master cylinder MC side, and the pressure is reduced. In this embodiment, the amount of pressure reduction is controlled by performing the valve opening amount of the out-side gate valve 3 by PWM control.

  As automatic brake control, in addition to the above-described automatic braking control, torque slip control for preventing driving wheel slip by generating braking force on the driving wheel when it is detected that the driving wheel slips, Vehicle motion control that generates a yaw moment in the direction to return the vehicle to the neutral state by generating braking force on the desired wheel when the over-steer state or over-understeer state occurs, provided by the driver other than the brake pedal BP When a braking operation is performed by an operating means that does not generate a master cylinder pressure, a by-wire control that determines a target hydraulic pressure (target deceleration) according to the braking operation and generates a braking force according to the target hydraulic pressure is performed. May be executed.

  Incidentally, in the case of the automatic braking control or the by-wire control described above, the wheel cylinder pressure of all the wheels is controlled to the same pressure, or the hydraulic pressure is supplied to all the wheel cylinders WC while giving a predetermined hydraulic pressure difference between the front and rear wheels. On the other hand, in the case of vehicle motion control, braking force may be generated only on one wheel. Regarding torque slip control, hydraulic pressure is supplied only to the wheel cylinder WC of the drive wheel.

  Next, details of the above-described automatic braking control will be described with reference to the flowchart of FIG. First, in step 101, it is determined whether or not the target deceleration (corresponding to the target hydraulic pressure) GT is larger than a preset retention prohibition threshold GMAX. If GT> GMAX, the process proceeds to step 102. The holding prohibition flag F_GMAX = 1 is set, and the feedback gain DGAINB is reset to 0.

  On the other hand, if GT ≦ GMAX in step 101, step 102 is skipped and the process proceeds to step 103. In step 103, braking control is executed for pressure reduction / holding / pressure increase processing according to the target deceleration GT based on whether the target deceleration GT is larger than a preset OFF threshold value THOFF. If GT> THOFF, the process proceeds to step 104 to execute the process for the target deceleration GT. If GT ≦ THOFF, it is determined that the braking control is not necessary, and the process proceeds to step 114. Then, an OFF process for ending the braking control is performed.

  That is, when the target deceleration GT is extremely small, an OFF process is performed, the pump 4 (motor 8) is stopped, the out-side gate valve 3 is opened, and the in-side gate valve 9 is closed. Is.

  In step 104, rapid pressure increase is executed based on whether or not the target deceleration gradient DGT, which is the slope from the current deceleration to the target deceleration GT, is less than a preset rapid increase threshold value THKYU. When the non-rapid pressure increase determination of DGT <THKYU, the process proceeds to step 105, and when the rapid pressure increase determination of DGT ≧ THKYU, the process proceeds to step 113. In this step 113, a rapid pressure increasing process is performed. In this case, an output for opening the in-side gate valve 9 is performed, an output with a duty ratio of 100% is performed for the motor 8, and the out-side gate valve is also operated. 3 is output with a duty ratio of 60%. As described above, in this embodiment, when a sudden pressure increase is necessary, a high braking force can be generated to cope with this.

  In step 105, it is determined whether or not the holding prohibition flag F_GMAX is set. If F_GMAX = 1, the process proceeds to step 107. If F_GMAX ≠ 1 (F_GMAX = 0), the process proceeds to step 106. In step 106, it is determined whether or not the target deceleration gradient DGT is larger than the pressure increase threshold value DBIC. If DGT> DBIC, the process proceeds to step 107 to determine whether the pressure increase is maintained or not, and DGT ≦ In the case of DBIC, the process proceeds to step 108 to determine whether the pressure is reduced or maintained.

  In step 107, it is determined whether or not the control signal SIGCNT is larger than a preset pressure increase holding threshold value DBIU. If SIGCNT> DBIU, the process proceeds to step 112 to execute the pressure increasing process. When SIGCNT ≦ DBIU, the routine proceeds to step 111 where the holding process is executed. Note that the pressure increase holding threshold value DBIU is set to a value on the pressure reducing side with respect to the normal holding region.

When the pressure increasing process is executed in step 112, the output duty ratio DUTY_P for the motor 8 (pump 4) is set to a value fp (SIGCNT) based on the duty characteristic map corresponding to the control signal SIGCNT shown in FIG. In addition, the in-side gate valve 9 is kept open. At this time, the out-side gate valve 3 is maintained in a closed state. At this time, the duty ratio DUTY_V output to the out-side gate valve 3 is set in the same manner as in the case of holding described later. A value obtained by adding a holding duty margin Dα to a value fk (target hydraulic pressure signal) based on a characteristic map corresponding to the target hydraulic pressure shown in FIG. That is, it is calculated by an arithmetic expression of DUTY_V = fk (target hydraulic pressure signal) + Dα. The control signal SIGCNT is calculated from the following arithmetic expression.
SIGCNT = PGAINF × GT + DGAINF × DGT + PGAINB × (GT−GL) + DGAINB × (DGT−DGL)
Here, PGAINF is a feedforward P gain, GT is a target deceleration, DGAINF is a feedforward D gain, DGT is a target deceleration gradient, PGAINB is a feedback P gain, GL is a vehicle deceleration, DGAINB is a feedback D gain, and DGL is This is the vehicle deceleration gradient.

  Further, as shown in FIG. 7, the vehicle deceleration GL is obtained by averaging the wheel speed signals from the four wheels by the averaging processing unit a, differentiating them by the differentiating unit b, and amplifying them by the amplifying unit c. It can be obtained by performing band pass processing with the filter d. Further, in this embodiment, a predetermined gain is given to the vehicle deceleration GL by the gain processing unit e, thereby forming a hydraulic pressure signal indicating the actual wheel cylinder pressure, which is used for the processing in this flowchart.

  In step 108, it is determined whether or not the target deceleration gradient DGT is smaller than the depressurization threshold value DBDC. If DGT <DBDC, the routine further proceeds to step 109, where the control signal SIGCNT is smaller than the depressurization holding threshold value DBDC. If it is determined whether or not the determination is YES, and if YES is determined in both step 108 and step 109, the process proceeds to step 110 to perform the decompression process, while if NO is determined in either step 108 or step 109 Then, the process proceeds to step 111 to perform holding processing. Note that the depressurization holding threshold value DBDC is set to a value on the pressure increasing side with respect to the normal holding region.

  In the case where the decompression process is executed in step 110, the in-side gate valve 9 is closed, the output duty ratio to the motor 8 (pump 4) is set to 0%, and the output duty ratio DUTY_V to the out-side gate valve 3 is It sets based on the map according to the control signal SIGCNT shown in FIG.

  In the case where the holding process is executed in step 111, in this embodiment, the driving of the motor 8 (pump 4) is stopped, the in-side gate valve 9 is closed, and the holding pressure is applied to the out-side gate valve 3. The duty ratio is output based on That is, the output duty ratio for the out-side gate valve 3 is set to a value fk (target hydraulic pressure signal) based on the characteristic map corresponding to the target hydraulic pressure shown in FIG. The value is added. That is, it is calculated by an arithmetic expression of DUTY_V = fk (target hydraulic pressure signal) + Dα.

  After performing any one of steps 110 to 114, the process proceeds to step 115, where a feedback process is performed on the out-side gate valve 3.

  FIG. 8 is a time chart showing an operation example of the first embodiment. As shown in this figure, when the pressure is increased, the output duty ratio DUTY_V with respect to the out-side gate valve 3 is changed according to the target hydraulic pressure, and when held, according to the target hydraulic pressure that is the actual wheel cylinder pressure at that time. Maintain the value. Therefore, the lower the target hydraulic pressure, the lower the output duty ratio DUTY_V. Further, at the time of pressure reduction, the output duty ratio DUTY_V corresponding to the control signal SIGCNT is output. In this case, the out-side gate valve 3 is opened by the wheel cylinder pressure and the urging force of the return spring (not shown).

  As described above, in the present embodiment, when the out-side gate valve 3 is closed, the duty ratio DUTY_V output to the out-side gate valve 3 at the time of pressure increase and during pressure reduction is set to the out-side gate. Since the determination is made based on the map shown in FIG. 5 in accordance with the target hydraulic pressure, which is the hydraulic pressure in the brake circuits 1 and 2 to be closed by the valve 3, while the out-side gate valve 3 is reliably maintained in the closed state. The operation of the out-side gate valve 3 can be performed with the minimum necessary current, and the effect that the power consumption and the amount of generated heat can be reduced while maintaining the control quality can be obtained. Incidentally, FIG. 9 shows the relationship between the hydraulic pressure that can maintain the closed state of the out-side gate valve 3 and the duty ratio. Thus, if the hydraulic pressure to be held decreases, the output duty ratio DUTY_V is It can be kept low. Note that the duty ratio DUTY_V output to the solenoid valve in this way may be corrected by the coil temperature or the ambient temperature of the solenoid valve.

  Further, in this embodiment, when the target deceleration GT is larger than the holding prohibition threshold value GMAX, the determination based on the target deceleration gradient in step 106 is skipped, and it is determined whether the pressure is increased or held in step 107. At this time, the feedback D gain DGAINB is reset to 0, and the deviation between the target deceleration gradient and the vehicle deceleration gradient is no longer reflected in the control signal SIGCNT, so that the vehicle deceleration GL becomes the target deceleration GT. The pressure is increased until the pressure reaches the value, and a high deceleration is reliably obtained without causing a delay in response, and a high control quality can also be obtained.

  Next, the brake device of Example 2 will be described. The brake device according to the second embodiment is a so-called brake-by-wire brake device that does not include the master cylinder MC and controls the wheel cylinder pressure using the hydraulic pressure of the pump as a hydraulic pressure source even during normal braking. The out-side gate valve 3 uses the same structure as that of the first embodiment, and the same components as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment. The description is omitted.

  That is, FIG. 10 is a brake circuit diagram showing only one system portion in the brake device of the second embodiment, and the main configuration is common to the first embodiment. The difference from the first embodiment is that the out-side gate valve 3 is connected to the suction side of the pump 4 via the low-pressure circuit 201. Therefore, when the out-side gate valve 3 is opened, the hydraulic pressure in the brake circuit 1 is reduced.

  A control unit (not shown) for controlling the operation of the valves 3, 5, 6 and the motor 8 is connected to a brake operation detecting means for detecting the operation of a brake pedal or a manual brake switch. When the driver performs a braking operation, the target hydraulic pressure and the control signal SIGCNT are obtained based on the detected value of the braking operation detecting means, and the out-side gate valve 3 and the motor 8 are PWM-controlled based on these values. Similarly to the first embodiment, during the ABS control, the inflow valve 5, the outflow valve 6 and the motor 8 are controlled.

  Although the embodiments have been described with reference to the drawings, the present invention is not limited to the configurations of the above embodiments. For example, the brake control device to which the present invention is applicable is not limited to the one shown in the embodiment. Further, in the embodiment, the pressure increase amount is controlled by driving the motor 8 (pump 4) at the time of pressure increase. However, an electromagnetic valve provided in the middle of the circuit connecting the hydraulic pressure source and the wheel cylinder is shown. You may make it control by opening and closing.

It is a brake circuit diagram showing a brake circuit in the brake control device of Example 1. FIG. 3 is a block diagram illustrating a configuration of a control unit according to the first embodiment. 3 is a flowchart illustrating braking control according to the first embodiment. It is a duty characteristic figure outputted to a pump in Example 1. It is a duty characteristic figure outputted to an out side gate valve at the time of pressure increase and maintenance in Example 1. It is a duty characteristic figure outputted to an out side gate valve at the time of pressure reduction in Example 1. FIG. 1 is a block diagram illustrating a configuration of a main part of Example 1. FIG. 3 is a time chart showing an operation example of the first embodiment. FIG. 6 is a characteristic diagram showing the relationship between the holding fluid pressure and the current value in Example 1. It is a brake circuit diagram which shows the brake circuit in the brake control apparatus of Example 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Brake circuit 2 Brake circuit 3 Out side gate valve 3a One valve 4 Pump 4a Suction circuit 4b Suction circuit 4c Discharge circuit 4d Check valve 4p Plunger 4r Pump chamber 5 Inflow valve 6 Outflow valve 7 Reservoir 8 Motor 9 Inside gate valve 10 Return circuit 11 Control unit 12 Wheel speed sensor 13 Running state detection means 201 Low pressure circuit BP Brake pedal MC Master cylinder RES Reservoir WC Wheel cylinder a Averaging unit b Differentiating unit c Amplifying unit d Low pass filter e Gain processing unit

Claims (6)

The wheel cylinder pressure can be arbitrarily adjusted by increasing, holding, and reducing the pressure to the wheel cylinder, and at least when the wheel cylinder pressure is held, there is a solenoid valve that closes the brake fluid to confine the brake fluid. Hydraulic pressure adjusting means,
Traveling state detecting means for detecting the traveling state of the vehicle;
In accordance with the traveling state of the vehicle detected by the traveling state detecting means, a control signal is outputted to the hydraulic pressure adjusting means to execute pressure increase / hold / reduced pressure to generate a desired braking force. Braking control means to execute;
In a brake control device comprising:
The brake control device according to claim 1, wherein the brake control unit outputs a predetermined duty ratio control signal lower than the maximum duty ratio to the solenoid valve when the hydraulic pressure adjusting unit is operated to increase the pressure. The running state detecting means is provided with an actual pressure detecting means for obtaining an actual pressure of the wheel cylinder,
The braking control means includes target hydraulic pressure calculation means for calculating a target hydraulic pressure of the wheel cylinder based on an input from the traveling state detection means, and an actual wheel cylinder detected by the actual pressure detection means during the braking control. 2. The brake control device according to claim 1, wherein the hydraulic pressure adjusting means is operated so that the pressure approaches the target hydraulic pressure calculated by the target hydraulic pressure calculating means.   The brake control device according to claim 2, wherein the actual pressure detecting means is means for calculating an actual wheel cylinder pressure based on a vehicle deceleration.   The braking control executed by the braking control means is an automatic braking control that obtains an inter-vehicle distance from a preceding vehicle based on an input from the traveling state detecting means and generates a braking force so that the inter-vehicle distance is an optimum value. The brake control device according to any one of claims 1 to 3, characterized in that: A brake circuit connected to the wheel cylinder for supplying brake fluid to the wheel cylinder;
A hydraulic pressure source for supplying brake fluid toward the brake circuit;
With
The solenoid valve is a normally open solenoid valve that is connected to a brake circuit and allows the brake fluid in the wheel cylinder to escape to a relatively low pressure circuit on the low pressure side,
The brake control means supplies the brake fluid from the hydraulic pressure source to the brake circuit at the time of pressure increase during braking control, temporarily or continuously closes the electromagnetic valve at the time of pressure reduction, and brakes from the hydraulic pressure source at the time of holding. The brake control device according to any one of claims 1 to 4, wherein the supply of the liquid is stopped and the electromagnetic valve is closed. A master cylinder,
A pump,
A first brake circuit connecting the master cylinder and the wheel cylinder;
A second brake circuit that connects the first brake circuit and the discharge side of the pump via a check valve that only allows flow to the first brake circuit side;
The normally open solenoid valve provided on the master cylinder side of the first brake circuit and on the master cylinder side of the connection position of the second brake circuit;
A third brake circuit on the first brake circuit for connecting a position closer to the master cylinder than the solenoid valve and a suction side of the pump;
A normally-open inflow valve provided on the wheel cylinder side from the connection position of the second brake circuit on the first brake circuit;
A fourth brake circuit on the first brake circuit for connecting a position closer to the wheel cylinder than the inflow valve and a suction side of the pump;
A normally closed outflow valve provided on the fourth brake circuit;
A reservoir provided on the suction side of the pump above the outflow valve on the fourth brake circuit;
When the wheel is likely to be locked, the inflow valve is closed, the outflow valve is opened to release the brake fluid in the wheel cylinder to the reservoir, and the brake fluid accumulated in the reservoir is discharged from the pump. Wheel lock avoidance control means for returning to the master cylinder side by operation;
When the braking control is automatically performed, the inflow valve and the outflow valve are deactivated, the pump is operated when increasing the pressure, the electromagnetic valve is closed when holding the pressure, and the electromagnetic valve is closed when reducing the pressure. Hydraulic pressure adjusting means for opening the valve;
The brake control device according to any one of claims 1 to 5, further comprising:

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