JP5044583B2 - Brake control device - Google Patents

Description

  The present invention relates to a brake control device that controls a brake pressure of a vehicle based on a driver's operation or a running state of the vehicle.

  Conventionally, it is possible to control the brake pressure independent of the brake operation by the driver (hereinafter referred to as automatic brake control), and improve the operation feeling of the brake operation member by the driver (depression feeling of the brake pedal). As a brake control device, there is a device disclosed in Patent Document 1.

  This device has a reservoir that can absorb the brake fluid discharged from the master cylinder, and a cut valve that can permit / prohibit the introduction of the brake fluid into the reservoir. If it is made, the cut valve is opened and the brake fluid discharged from the master cylinder is stored in the reservoir. This ensures an invalid stroke (stroke of the brake pedal that does not substantially increase the wheel cylinder pressure), and makes the wheel cylinder pressure increase characteristic relative to the pedal stroke closer to the characteristics during normal braking operation (non-automatic brake control). ing. Thereby, even when a brake operation is performed during execution of the automatic brake control, the operation feeling is improved so as not to give the driver a sense of incongruity.

JP 2006-159949 A

  However, in the above apparatus, since it is necessary to add a reservoir and a cut valve, there is a problem that the system becomes complicated and the unit becomes large. The present invention has been made paying attention to the above problems, and its purpose is to improve operation feeling even when a brake operation is performed during execution of automatic brake control without adding special parts. An object of the present invention is to provide a brake control device that can be used.

  In order to achieve the above object, the brake control device of the present invention includes a reservoir capable of storing brake fluid, a pump for supplying discharge pressure to the wheel cylinder, a master cylinder and the wheel cylinder, and a gate-out valve. The first passage, the master cylinder and the wheel cylinder communicate with each other, the second passage provided with the pump, the wheel cylinder communicates with the reservoir, the decompression passage provided with the pressure reducing valve, and the suction side of the reservoir and the pump. A scraping passage communicating therewith, and a gate-in valve provided between the master cylinder and the pump in the second passage. When an increase in the brake operation force by the driver is detected, the pump is driven and the gate-out valve is The valve was closed and the gate-in valve and the pressure reducing valve were opened.

  Therefore, even when the driver performs a brake operation while controlling the brake pressure, the brake operation member can be operated by sucking the brake fluid from the master cylinder by the pump. Therefore, without adding special parts, it is possible to suppress the driver from feeling uncomfortable (stepping feeling) and improve the brake operation feeling.

It is a hydraulic unit (brake circuit diagram) to which the brake control device of Example 1 is applied. The flow of the control performed by the automatic brake control of Example 1 is shown (when brake operation is performed). The flow of the control performed by the automatic brake control of Example 1 is shown (when brake operation is not performed). It is a time chart when automatic brake control is performed in Example 1 (when a brake operation is not performed). 6 is a time chart when a brake operation is performed during execution of automatic brake control in the first embodiment. The flow of the brake fluid during execution of the stone step prevention control in the first embodiment is shown. It is a time chart at the time of brake operation performed during execution of automatic brake control in Example 1 and a comparative example.

  Hereinafter, the form which implement | achieves the brake control apparatus of this invention is demonstrated based on the Example shown on drawing.

(Brake circuit configuration)
FIG. 1 is a brake circuit diagram of a hydraulic unit HU to which the brake control device of the first embodiment is applied. The hydraulic unit HU is connected to the master cylinder M / C and the wheel cylinders 5a to 5d of the wheels FL to RR. Hereinafter, a plurality of four wheels corresponding to each of the four wheels will be distinguished by adding symbols a, b, c and d, where a is the front left wheel FL, b is the front right wheel FR, and c is the rear. The left wheels RL and d represent those corresponding to the rear right wheel RR, respectively. Similarly, a plurality of pipe systems corresponding to each of the piping systems P and S are distinguished by adding symbols p and s.

  The brake piping system of the vehicle is divided into two independent systems, that is, a primary P system and a secondary S system. The P system is connected to the wheel cylinder 5a of the front left wheel FL and the wheel cylinder 5d of the rear right wheel RR, and the S system is connected to the wheel cylinder 5b of the front right wheel FR and the wheel cylinder 5c of the rear left wheel RL. It has a so-called X piping structure. In addition, not only X piping but front and rear piping may be used.

  The brake pedal BP is a brake operation member that strokes (displaces) in response to the driver's depression, and transmits the driver's depression operation force to the booster BS. The booster BS amplifies the force transmitted from the brake pedal BP and transmits the amplified force to the master cylinder M / C. As the power source of the booster BS, for example, the negative pressure of the engine can be used, but the power of the electric motor may be used and is not particularly limited.

  The master cylinder M / C is a so-called tandem type and is well known. The two hydraulic chambers arranged in the front-rear direction are connected to a reservoir tank (hereinafter referred to as an external reservoir RES) provided outside the hydraulic unit HU, and receive a supply of brake fluid. One hydraulic chamber is connected to a P-system brake circuit, and the other hydraulic chamber is connected to an S-system brake circuit. The master cylinder M / C generates a hydraulic pressure (master cylinder pressure) corresponding to the force transmitted from the booster BS in the two hydraulic pressure chambers and supplies it to the brake circuits of each system.

  In the hydraulic unit HU, a gate-out valve 1, a gate-in valve 2, a pressure increase control valve 6, a pressure reduction control valve 8, a pump P, and an internal reservoir 15 are provided for each brake circuit of each system. Is provided. Hereinafter, the configuration of the brake circuit will be described taking the P system as an example. The brake circuit of the P system is provided separately from the first passage 10p that communicates the master cylinder M / C and the wheel cylinder 5, and the first passage 10p, and communicates the master cylinder M / C and the wheel cylinders 5a and 5d. 2 passages (a suction passage 11p and a discharge passage 12p), a decompression passage 13p communicating the wheel cylinders 5a, 5d and the internal reservoir 15p, and a scraping passage 14p communicating the internal reservoir 15p and the suction side of the pump Pp. Yes.

  One end of the first passage 10p is connected to the master cylinder M / C. The other end of the first passage 10p is branched into two passages 10a and 10d, which are connected to the wheel cylinders 5a and 5d of the left front wheel FL and the right rear wheel RR, respectively.

  A gate-out valve 1p is provided in the first passage 10p. The gate-out valve 1p is a normally-open proportional solenoid valve that opens and closes at a valve opening proportional to the command current from the control unit CU. A check valve (check valve) 3p is provided in parallel with the gate-out valve 1p. When the master cylinder side is the upstream and the wheel cylinder side is the downstream, the check valve 3p prevents the flow of brake fluid from the downstream to the upstream.

  The branch passages 10a and 10d are provided with pressure increase control valves 6a and 6d, respectively. The pressure increase control valves 6a and 6d are normally open on / off solenoid valves which are controlled to two positions by a command current from the control unit CU and perform an opening / closing operation. A check valve 7a is provided in parallel with the pressure increase control valve 6a. The check valve 7a prevents the flow of brake fluid from upstream to downstream. The same applies to the check valve 7d.

  In the first passage 10p, one end of the suction passage 11p is connected between the master cylinder M / C and the gate-out valve 1p. The other end of the suction passage 11p is connected to the suction side of the pump Pp. A gate-in valve 2p is provided in the suction passage 11p. The gate-in valve 2p is a normally closed on / off solenoid valve that is controlled to two positions by a command current from the control unit CU and performs an opening / closing operation.

  One end of a discharge passage 12p is connected to the discharge side of the pump Pp. The discharge passage 12p joins the downstream side of the gate-out valve 1p in the first passage 10p (and the upstream side of the pressure increase control valves 6a and 6d), and passes through the branch passages 10a and 10d (that is, the first passage 10p). Are connected to the wheel cylinders 5a and 5d. Further, the discharge passage 12p communicates with the master cylinder M / C through the first passage 10p (gate-out valve 1p). The discharge passage 12p is provided with a check valve 4p that prevents the flow of brake fluid from the master cylinder M / C toward the discharge side of the pump Pp.

  One end of a decompression passage 13a is connected to the branch passage 10a on the downstream side of the first passage 10p between the pressure increase control valve 6a and the wheel cylinder 5a. Similarly, one end of a pressure reducing passage 13d is connected to the branch passage 10d between the pressure increase control valve 6d and the wheel cylinder 5d. The other end sides of the decompression passages 13a and 13d join together to form one decompression passage 13p and are connected to the internal reservoir 15p. Thus, the decompression passage 13p (13a, 13d) communicates the wheel cylinders 5a, 5d and the internal reservoir 15p.

  Pressure reducing control valves 8a and 8d are provided in the pressure reducing passages 13a and 13d, respectively. The decompression control valves 8a and 8d are normally closed proportional solenoid valves that perform opening and closing operations at a valve opening degree proportional to the command current from the control unit CU.

  One end of the scraping passage 14p is connected to the internal reservoir 15p while sharing a part of the passage with the decompression passage 13p. The other end of the scraping passage 14p is connected between the gate-in valve 2p and the pump Pp in the suction passage 11p. In this manner, the scraping passage 14p shares a part of the passage with the decompression passage 13p and the suction passage 11p, thereby communicating the internal reservoir 15p with the suction side of the pump Pp. In other words, a scraping passage 14p for scraping the brake fluid stored in the internal reservoir 15p by the pump Pp is provided separately from the suction passage 11p.

  A check valve 9p is provided in the scraping passage 14p. The check valve 9p prevents the flow of brake fluid from the suction passage 11p (master cylinder M / C) side toward the internal reservoir 15p.

  In the P-system brake circuit configured as described above, the gate-out valve 1p intermittently connects (communication / shutoff) between the master cylinder M / C and the pressure increase control valves 6a and 6d in the first passage 10p. Intermittently between the discharge side of the pump Pp and the master cylinder M / C. The check valve 3p in parallel with the gate-out valve 1p prevents the flow of brake fluid from the circuit on the discharge side of the pump Pp (and the downstream side of the gate-out valve 1p) toward the master cylinder M / C. When the gate-out valve 1p and the gate-in valve 2p are closed, if the driver depresses the brake pedal BP and "master cylinder pressure> (circuit pressure on the discharge side of the pump Pp)", the check valve 3p opens. By controlling the valve, the master cylinder pressure can be transmitted to the circuit on the discharge side of the pump Pp.

  The gate-in valve 2p intermittently connects between the master cylinder M / C and the suction side of the pump Pp (suction passage 11p). The pressure increase control valves 6a and 6d supply the master cylinder pressure or pump pressure to the wheel cylinders 5a and 5d by opening the valve, and shut off the supply by closing the valve. In the check valve 7a, in particular, when the pressure increase control valve 6a is closed in the anti-skid control (ABS control), the driver depresses the brake pedal BP so that “(wheel cylinder pressure of the front left wheel FL)> master cylinder pressure”. When this happens, the valve is opened in response to this stepping back operation, and the wheel cylinder pressure is released to the master cylinder M / C so that the pressure can be reduced. The same applies to the check valve 7d.

  The decompression control valves 8a and 8d open the valve to supply the brake fluid of the wheel cylinders 5a and 5d to the internal reservoir 15p to release the wheel cylinder pressure, and close the supply by closing the valve. The internal reservoir 15p is a reservoir provided inside the hydraulic pressure unit HU, and stores brake fluid sent from the wheel cylinders 5a, 5d, etc. via the pressure reduction control valves 8a, 8d.

  The brake circuit of the S system is configured in the same manner as the P system. Note that the hydraulic pressure (master cylinder pressure) generated by the master cylinder M / C is detected in the first passage 10p (upstream of the gate-out valve 1p) or the suction passage 11p (upstream of the gate-in valve 2p) of the P system. A master cylinder pressure sensor 20 is provided. The detected value of the master cylinder pressure represents the operating force of the brake pedal BP by the driver.

  The pumps Pp and Ps are external gear pumps that are respectively provided in the P system and the S system and are rotationally driven by the same drive source (motor M). An inscribed gear pump such as a trochoid may be used, or a vane pump or a plunger pump may be used.

  The pumps Pp and Ps function as a hydraulic pressure source other than the master cylinder M / C in each system. For example, the pumps Pp and Ps scrape brake fluid from the internal reservoir 15 via the scraping passage 14 and via the discharge passage 12 and the first passage 10. Return the brake fluid to the master cylinder M / C. Further, the brake fluid is sucked from the master cylinder M / C through the suction passage 11 and supplied to the wheel cylinder 5 through the discharge passage 11.

  The motor M is a servo motor whose rotation speed is controlled by a command current from the control unit CU, and is integrally attached to the hydraulic unit HU. As the motor M, for example, a DC brushless electric motor can be used, but an AC motor or a brush motor may be used, and is not particularly limited.

  During normal braking that does not control the wheel cylinder pressure, the actuators (electromagnetic valves such as the gate-out valve 1 and motor M) are de-energized, the gate-in valve 2 and the pressure-reducing control valve 8 of both systems are closed, and gate-out occurs. The valve 1 and the pressure increase control valve 6 are opened, and the motor M is turned off. In this state (hereinafter referred to as a normal brake state), the master cylinder pressure generated by the driver's operation of the brake pedal is supplied to the wheel cylinders 5 of all the wheels, and the braking force according to the driver's request is generated.

  The control unit CU receives the detection value sent from the master cylinder pressure sensor 20 and the information on the running state sent from the vehicle side, and controls each actuator of the hydraulic unit HU based on the built-in program. As a result, automatic brake control and anti-skid control (hereinafter referred to as ABS control) in adaptive cruise control (hereinafter referred to as ACC) and vehicle behavior control (hereinafter referred to as VDC) can be executed.

  Here, ACC is a control that automatically accelerates or decelerates so as to travel following the preceding vehicle while ensuring an appropriate inter-vehicle distance. VDC is a control that maintains vehicle stability by controlling the vehicle attitude. Specifically, the actual yaw rate of the vehicle is detected by a yaw rate sensor or the like, and the target yaw rate is determined by using a steering angle sensor or the like. The braking force is applied only to specific wheels so that the target yaw rate matches the actual yaw rate. The ABS control is a control for preventing wheel lock by performing increase / decrease control of the wheel cylinder pressure so that the slip ratio of the wheel becomes a desired value.

(ABS control)
During ABS control, for example, when the front left wheel FL is detected to be locked and the wheel cylinder 5a is being controlled, the pressure increase control valve 6a is basically closed with the gate-out valve 1p open and the gate-in valve 2p closed. By opening the decompression control valve 8a, the brake fluid in the wheel cylinder 5a is discharged to the internal reservoir 15p to perform decompression. When the front left wheel FL recovers from the locking tendency, the pressure reducing control valve 8a is closed to maintain the wheel cylinder pressure. Further, the pressure increase control valve 6a is opened to increase the pressure appropriately. Also, the pump Pp is operated at the start of pressure reduction, and the brake fluid that has escaped to the internal reservoir 15p during pressure reduction is scraped from the reservoir 15p and returned to the master cylinder M / C side.

  On the other hand, the S system that does not perform ABS control is in a normal brake state except that the pump Ps operates. Since the brake fluid is not stored in the internal reservoir 15s and the gate-in valve 2s is also closed, the pump Ps runs idle and does not suck or discharge the brake fluid.

(Automatic brake control)
2 and 3 show the flow of control executed by the control unit CU of the first embodiment when the wheel cylinder pressure of each wheel is controlled by automatic brake control such as ACC.

  In step S10 in FIG. 2, it is determined whether or not the wheel cylinder pressure is to be controlled based on information relating to the running state sent from the vehicle. When the wheel cylinder pressure is controlled, the wheel cylinder pressure target value (command value) corresponding to the necessary braking force is received for each wheel cylinder 5a to 5d of each wheel, and the process proceeds to S11. If the wheel cylinder pressure is not controlled, the process proceeds to S17. The wheel cylinder pressure target value is determined from the target deceleration of the own vehicle (calculated from the deviation between the target value of the inter-vehicle distance and the detected value) in ACC, for example.

  In S11, based on the detected value of the master cylinder pressure sensor 20, it is detected whether or not the driver has depressed the brake pedal BP. When the master cylinder pressure detection value exceeds a predetermined value (a predetermined positive value close to zero), it is determined that the brake pedal BP has been depressed, and the process proceeds to S13. If the detected value is not more than the predetermined value (close to zero), it is determined that the brake pedal BP is not depressed, and the process proceeds to S12.

(When brake operation is not performed during automatic brake control)
Hereinafter, the contents of the control executed in S12 when it is determined NO in S11, that is, when the brake operation is not performed during the automatic brake control will be described with reference to FIG.
In S1, it is determined whether or not the wheel cylinder pressure (of the wheel cylinder 5) is increased. This determination is made by comparing the target value of the wheel cylinder pressure with the estimated value. Note that instead of the estimated value, a wheel cylinder pressure sensor may be provided to detect the actual value of the wheel cylinder pressure. If the pressure is increased, the process proceeds to S2. If the pressure is not increased, the process proceeds to S4.

In S2, the gate-in valve 2 (of the system to which the wheel cylinder 5 belongs) is opened, the gate-out valve 1 is closed, the pressure-increasing control valve 6 (corresponding to the wheel cylinder 5) is kept open, and the pressure-reducing control valve 8 is proportionally controlled. Also, the motor is turned on and the pump P is driven. As a result, the pump pressure is supplied to the wheel cylinder 5 via the pressure increase control valve 6, and the wheel cylinder pressure is increased. The pressure increase amount is adjusted by proportional control of the pressure reducing control valve 8. Thereafter, the process proceeds to S3.
When the pressure reduction control valve 8 is proportionally controlled, a large current is once applied immediately after the start of pressure increase to make it completely open. Thereafter, the current value is decreased until the pressure reducing control valve 8 reaches the intermediate opening.

  In S3, it is determined whether or not the wheel cylinder pressure has reached a target value. This determination is made by comparing the estimated value of the wheel cylinder pressure with the target value. When the target value is reached, the process proceeds to S16. If not, the process returns to S2 and continues to increase the wheel cylinder pressure.

  In S4, it is determined whether to reduce the wheel cylinder pressure. This determination is made by comparing the target value of the wheel cylinder pressure with the estimated value. If the pressure is reduced, the process proceeds to S5. If the pressure is not reduced, the process proceeds to S7.

  In S5, the gate-in valve 2 is closed, the opening degree of the gate-out valve 1 is proportionally controlled, the pressure increase control valve 6 is kept open, and the pressure reduction control valve is closed. Also, the motor is turned on and the pump P is driven. As a result, the brake fluid inside the wheel cylinder 5 is smoothly drained to the external reservoir RES via the gate-out valve 1 (first passage 10), and the wheel cylinder pressure is reduced. The amount of pressure reduction is adjusted by proportional control of the gate-out valve 1. Further, the brake fluid accumulated in the internal reservoir 15 is scraped out by the pump P and returned to the external reservoir RES via the gate-out valve 1 (first passage 10). Thereafter, the process proceeds to S6.

  In S6, as in S3, it is determined whether or not the wheel cylinder pressure has reached the target value. When the target value is reached, the process proceeds to S16. If not, the process returns to S5 and continues to reduce the wheel cylinder pressure.

  In S7, the wheel cylinder pressure is maintained without being increased or decreased. The gate-in valve 2 is closed, the gate-out valve 1 is closed, the pressure increase control valve 6 is kept open, and the opening degree of the pressure reduction control valve 8 is proportionally controlled. Further, the motor M is turned on and the pump P is driven. By proportionally controlling the pressure reducing control valve 8, the pressure reducing passage 13 is communicated, and the brake fluid leaks through the pressure reducing control valve 8. Further, since the pump P is operating, the brake fluid circulates as “(internal reservoir 15 →) pump P → pressure increase control valve 6 → pressure reduction control valve 8 (→ internal reservoir 15) → pump P”. For this reason, the amount of brake fluid entering and exiting the wheel cylinder 5 hardly changes, and the wheel cylinder pressure is maintained at the target value. Thereafter, the process proceeds to S16.

(When brake operation is performed during automatic brake control)
Next, the flow of control when a brake operation is performed during automatic brake control will be described. The steps after S13 in FIG. 2 are executed when the driver depresses the brake pedal BP during the automatic brake control, that is, while the wheel cylinder pressure is controlled by the flow of S11 → S12 → S16 → S11. Shows the flow.

  In S13, based on the detected value of the master cylinder pressure sensor 20, it is determined whether or not the master cylinder pressure is increasing. If it is increasing, it is determined that the brake operation force is increasing, and the process proceeds to S14. If it is not increasing, that is, if the master cylinder pressure is being maintained or decreasing, it is determined that the brake operating force has not increased, and the process proceeds to S18.

  In this control flow, after executing S13 for the first time (that is, after the brake pedal BP is depressed by the driver), until NO is determined in S11 (that is, the brake pedal BP cannot be depressed), the wheel cylinder The target value of pressure is determined as follows according to another control flow. That is, when the detected value of the master cylinder pressure is equal to or less than the target value of the wheel cylinder pressure in the automatic brake control, the wheel cylinder pressure target value set in the automatic brake control is maintained. On the other hand, when the master cylinder pressure detection value is higher than the wheel cylinder pressure target value in the automatic brake control, a wheel cylinder pressure target value corresponding to the master cylinder pressure detection value is set.

(Control while increasing operating force)
In S14, a stone step prevention control is performed. That is, the gate-in valve 2 (of the system to which the wheel cylinder 5 belongs) is opened (the opening degree of the gate-in valve 2 is duty-controlled), the gate-out valve 1 is closed, and the pressure is increased (corresponding to the wheel cylinder 5). The control valve 6 is kept open, and the opening degree of the pressure reducing control valve 8 is proportionally controlled. Further, the motor M is turned on and the pump P is driven.

  Since the pump P is operating, the brake fluid is sucked into the pump P from the master cylinder M / C through the suction passage 11 and discharged to the discharge passage 12. By adjusting the opening degree of the pressure reducing control valve 8 by proportional control, the amount of brake fluid required to achieve the wheel cylinder pressure target value among the brake fluid supplied to the discharge passage 12 is supplied to the wheel cylinder 5. At the same time, an unnecessary amount of brake fluid is leaked to the internal reservoir 15 via the pressure reducing passage 13. By such leakage control, excess brake fluid sent from the master cylinder M / C is stored in the internal reservoir 15 while adjusting the wheel cylinder pressure. Thereafter, the process proceeds to S15.

  In S15, it is determined whether or not the wheel cylinder pressure has reached a target value. This determination is made by comparing the estimated value of the wheel cylinder pressure with the target value. When the target value is reached, the process proceeds to S16. If it has not reached, the process returns to S14 and continues the stone step prevention control.

  In S16, it is determined whether or not to end the control of the wheel cylinder pressure based on the information on the running state sent from the vehicle. When the process ends, the process proceeds to S17. When continuing to control the wheel cylinder pressure, the process returns to S11.

  In S17, processing for terminating the automatic brake control is performed. That is, the gate-in valve 2 is closed, the gate-out valve 1 is opened, the pressure-increasing control valve 6 is kept open, the pressure-reducing control valve 8 is closed, the motor M is turned off, and the normal braking state is established. As a result, the master cylinder M / C and the wheel cylinder 5 communicate with each other (the first passage 10), and the master cylinder pressure can be directly supplied to the wheel cylinder 5. The wheel cylinder pressure is increased by the driver's brake operation. Will come to be.

(Control while operating force is not increasing)
In S18, as in S1, it is determined whether or not to increase the wheel cylinder pressure. When the pressure is increased, the process proceeds to S19, and when the pressure is not increased, the process proceeds to S21.

  In S19, the gate-in valve 2 is opened, the gate-out valve 1 is closed, the pressure-increasing control valve 6 is kept open, and the opening degree of the pressure-reducing control valve 8 is proportionally controlled. Further, the motor M is turned on and the pump P is driven. Thereby, the wheel cylinder pressure is increased. Since the pump P is operating, the brake fluid is drawn into the pump P from the master cylinder M / C and discharged to the discharge passage 12. The brake fluid supplied to the discharge passage 12 is supplied to the wheel cylinder 5 as necessary, and the remaining brake fluid is leaked to the internal reservoir 15 via the pressure reducing control valve 8. Thereafter, the process proceeds to S20.

  In S20, as in S15, it is determined whether or not the wheel cylinder pressure has reached the target value. When the target value is reached, the process proceeds to S16. If not, the process returns to S19 and continues to increase pressure.

  In S21, it is determined whether or not the wheel cylinder pressure is reduced as in S4. If the pressure is reduced, the process proceeds to S22. If the pressure is not reduced, the process proceeds to S24.

  In S22, processing different from S5 is performed to reduce the wheel cylinder pressure. That is, the gate-in valve 2 is closed, the gate-out valve 1 is closed, the pressure increase control valve 6 is kept open, and the opening degree of the pressure reduction control valve 8 is proportionally controlled. Further, the motor M is turned on and the pump P is driven. By proportionally controlling the depressurization control valve 8 (increasing the opening), the brake fluid in the wheel cylinder 5 is drained to the internal reservoir 15 via the depressurization control valve 8, and the wheel cylinder pressure is reduced. Since the pump P is operating, the brake fluid circulates as “(internal reservoir 15 →) pump P → pressure increase control valve 6 → pressure reduction control valve 8 (→ internal reservoir 15) → pump P”, The amount of brake fluid is stored in the internal reservoir 15. Thereafter, the process proceeds to S23.

  In S23, as in S15, it is determined whether or not the wheel cylinder pressure has reached the target value. When the target value is reached, the process proceeds to S16. If not, the process returns to S22 to continue the decompression.

  In S24, the same processing as in S7 is performed to maintain the wheel cylinder pressure. Thereafter, the process proceeds to S16.

  Next, the operation of the brake control device of the first embodiment will be described.

(Time chart when brake operation is not performed)
FIG. 4 is a time chart when the automatic brake control is executed according to the control flow of FIGS. 2 and 3 (when the brake operation is not performed during the control), and the operation of each valve and the motor M (pump P). The state, the amount of liquid in the internal reservoir 15 and the time change of the wheel cylinder pressure (actual value) are shown. Since no brake operation is performed, the stroke of the brake pedal BP (hereinafter referred to as pedal stroke) is zero, and no master cylinder pressure is generated. Hereinafter, only the front left wheel FL (P system) will be described by taking as an example the case where ACC is executed, that is, when similar wheel cylinder pressure control is executed on all wheels of the P system and S system.

  Until the time t1 when the control is started, the normal brake state (S17) and the master cylinder pressure are not generated, so the hydraulic pressure of the wheel cylinder 5a (hereinafter referred to as the wheel cylinder pressure) is zero. Further, the motor is turned off, the pump Pp is not operating, and the amount of liquid stored in the internal reservoir 15p (hereinafter referred to as the reservoir liquid amount) is zero.

  At time t1, ACC is started based on the information about the running state sent from the vehicle. During ACC, the wheel cylinder pressure target value (the one-dot chain line in FIG. 4) is sequentially received, the motor M is turned on to operate the pump Pp, and the pressure increase control valve 6a is maintained in a fully opened state.

  At t1, the pressure increase of the wheel cylinder 5a is started and the pressure is increased until t2 when the wheel cylinder pressure reaches the target value (S2, S3). During the pressure increase in the wheel cylinder 5a, the gate-in valve 2p of the system (P system) is opened and the gate-out valve 1p is closed. The opening degree of the pressure reducing control valve 8a is proportionally controlled after giving a large current to t1 immediately after the start of pressure increase to be fully opened and then gradually reduced to an intermediate opening degree by decreasing the current value.

  At this time, the brake fluid is sucked from the master cylinder M / C (external reservoir RES connected to the master cylinder M / C) via the suction passage 11p by the pump Pp, and a predetermined pump pressure is supplied to the discharge passage 12a. As a result, the discharge pressure of the pump Pp is supplied to the wheel cylinder 5a via the pressure increase control valve 6a (discharge passages 12p, 10a), and the wheel cylinder pressure is increased. At this time, the opening degree of the pressure reduction control valve 8a is proportionally controlled so that the wheel cylinder pressure approaches the target value. By the proportional control of the pressure reducing control valve 8a, the brake fluid leaks through the pressure reducing passages 13a and 13p to the internal reservoir 15p, and the amount of the reservoir fluid slightly increases.

  The proportional control is started after the decompression control valve 8a is fully opened as described above because the spring of the decompression control valve 8a (a return spring that constantly biases the valve body in the valve closing direction against the electromagnetic force). This is because it is easier to maintain the intermediate opening and to more accurately control the valve opening. Further, since the pressure reducing control valve 8a has a faster response to the command current than the motor M, even if it is fully opened once and then has an intermediate opening, the wheel cylinder pressure is reduced at the initial stage of motor rotation (from the wheel cylinder 5a to the pressure reducing passage). This is because a brake fluid leak to 13a is unlikely to occur.

  Since the wheel cylinder pressure reaches the target value at t2, the wheel cylinder pressure is maintained thereafter (S7). While the hydraulic pressure of the wheel cylinder 5a is maintained, the gate-in valve 2p and the gate-out valve 1p of the system (P system) are closed, and the opening degree of the pressure reducing control valve 8a is proportionally controlled (maintained at an intermediate opening degree). A closed passage “(internal reservoir 15p →) pump Pp → pressure increase control valve 6a → depressurization control valve 8a (→ internal reservoir 15p) → pump Pp” is formed, and brake fluid circulates in the closed passage. No brake fluid is supplied to or discharged from the cylinder 5a, and no brake fluid is stored in the internal reservoir 15p. Therefore, the wheel cylinder pressure is maintained at the target value, and the reservoir fluid amount does not change.

  At t3, the wheel cylinder pressure target value is set to zero, and the start of pressure reduction is determined. After t3, the wheel cylinder 5a is depressurized until the wheel cylinder pressure reaches the target value t4 (S5, S6). By closing the pressure reducing control valve 8a and proportionally controlling (gradually increasing) the opening degree of the gate-out valve 1p of the system (P system), the discharge side of the wheel cylinder 5a and the pump Pp and the master cylinder M / Communicate with C. As a result, the brake fluid is returned from the wheel cylinder 5a to the external reservoir RES, and the wheel cylinder pressure is reduced. Further, by closing the gate-in valve 2p and driving the pump Pp, the brake fluid is scraped from the internal reservoir 15 and returned to the external reservoir RES. Accordingly, the reservoir fluid amount is reduced.

  At t4, the wheel cylinder pressure is reduced to the target value (zero), and the reservoir fluid volume is reduced to zero. Further, the gate-out valve 1p is fully opened. Also, at t4, the ACC is terminated based on the information on the traveling state sent from the vehicle. Thereafter, the normal brake state (S17) is restored.

(Time chart when brake operation is performed)
FIG. 5 is a time chart similar to FIG. 4 when the control is executed according to the control flow of FIGS. 2 and 3 when the brake operation is performed during the automatic brake control. The change in (detected value) is also shown. Only the front left wheel FL (P system) will be described by taking as an example a case where a brake operation is performed during execution of ACC (foil cylinder pressure maintenance).

  The process is the same as in FIG. 4 until t21 when the brake operation is performed. After t2, the wheel cylinder pressure is maintained until t21 (S7). That is, the brake fluid circulates in the closed passage “(internal reservoir 15p →) pump Pp → pressure increase control valve 6a → pressure reduction control valve 8a (→ internal reservoir 15p) → pump Pp”, and the wheel cylinder pressure reaches the target value. Is retained. For convenience of explanation, the reservoir liquid amount at this time is considered to be zero. As in FIG. 4, it is assumed that the wheel cylinder pressure target value in ACC (hereinafter referred to as holding pressure Pw0) is constant until t3.

  At t21, the brake pedal BP is depressed by the driver. The master cylinder pressure is generated by depressing the brake pedal BP, and the detected value of the master cylinder pressure exceeds a predetermined value (set to a positive value close to zero) immediately after t21. Therefore, after t21, the control flow from S13 onward in FIG. 2 is executed until the pedal depression is completed (the master cylinder pressure detection value is equal to or less than the predetermined value) t26.

  From t21 to t23, the brake pedal BP is increased. Thereby, the master cylinder pressure (detected value) increases from t21 to t23. Therefore, the stone step prevention control is executed (S14), and the hydraulic pressure (wheel cylinder pressure) of the wheel cylinder 5a is controlled to the target value (holding pressure Pw0) (S15). Specifically, the opening degree of the gate-in valve 2p is duty-controlled while the gate-out valve 1p of the system (P system) is closed, and the opening degree of the decompression control valve 8a is proportionally controlled.

  FIG. 6 schematically shows the flow of brake fluid in the oil passage during execution of the stone step prevention control. Although the hydraulic pressure from the master cylinder M / C is applied to the pump Pp via the suction passage 11p, since the pump Pp is operating, the brake fluid is sucked by the pump Pp and supplied to the discharge passage 12p. The brake fluid supplied to the discharge passage 12p is sent to the internal reservoir 15p side through the open pressure reducing control valve 8a.

  In FIG. 6, the gate-in valve 2p and the pressure-reducing control valve 8a are shown in a closed state for convenience, but are energized and opened during execution of the stone-step prevention control. Similarly, although the gate-out valve 1p is shown in the open state in FIG. 6, the gate-out valve 1p is energized and closed during execution of the stone step prevention control. Further, the stepping prevention control can be executed for all wheels or only one wheel, both P and S systems or only one system.

  From t21 to t22, the master cylinder pressure (detected value) is the holding pressure Pw0 or less. For this reason, the holding pressure Pw0 is maintained as the wheel cylinder pressure target value. Then, the opening degree of the pressure reducing control valve 8a is increased by proportional control so that the brake fluid newly sucked from the master cylinder M / C is leaked (supplied) to the internal reservoir 15p and not supplied to the wheel cylinder 5a. Then, the opening degree of the pressure reducing control valve 8a is adjusted. As a result, the wheel cylinder pressure is maintained at the target value (holding pressure Pw0), and the brake fluid is accumulated in the internal reservoir 15p by the amount of fluid sent from the master cylinder M / C, so that the reservoir fluid amount increases.

  After t22, the master cylinder pressure (detected value) becomes higher than the holding pressure Pw0. Therefore, the wheel cylinder pressure target value is adjusted in accordance with the increase in the master cylinder pressure so that the wheel cylinder pressure becomes a value corresponding to the master cylinder pressure. Set (re). Then, the opening degree of the pressure reducing control valve 8a is decreased by proportional control, and the brake fluid newly sucked from the master cylinder M / C is supplied to the wheel cylinder 5a so as not to leak (do not supply) to the internal reservoir 15p. Next, the opening degree of the pressure reducing control valve 8a is adjusted. As a result, the wheel cylinder pressure is increased to be equivalent to the master cylinder pressure, and the reservoir fluid amount becomes constant.

  As described above, during the period from t21 to t23 when the driver depresses the brake pedal BP, the brake fluid from the master cylinder M / C is supplied to the internal reservoir 15p or the wheel cylinder 5a. Therefore, as shown in FIG. 5, the pedal stroke increases in accordance with the driver's brake operation force (pedal depression force) from t21 to t23. That is, while maintaining and controlling the wheel cylinder pressure at the target value, it is possible to increase the pedal stroke in accordance with the pedal depression force immediately after the start of the pedal depression, thereby ensuring good operation feeling.

  In addition, while the master cylinder pressure is increasing from t21 to t23, the opening degree of the gate-in valve 2 is duty-controlled (S14). As a result, an excessive increase in pressure in the suction passage 11p connecting the downstream side of the gate-in valve 2p and the suction side of the pump Pp is suppressed, and an appropriate amount of brake fluid is supplied to the pump Pp. Therefore, the brake fluid from the master cylinder M / C can be supplied into the closed passage at an appropriate speed, and the brake fluid can smoothly flow through the closed passage. It is possible to improve the above-described effect of ensuring good operation feeling while maintaining and controlling.

  At t23, the driver finishes increasing the brake pedal BP. That is, the depression force (pedal depression force) becomes constant and does not increase. Along with this, the master cylinder pressure (detected value) also becomes constant. Therefore, the stone step prevention control is stopped, and the predetermined wheel cylinder pressure control is executed (S18 to S24).

  After t23, the master cylinder pressure is constant and higher than the holding pressure Pw0 until t24 when the brake pedal BP starts to be returned, so the wheel cylinder pressure target value is set to a constant value Pw1 corresponding to the master cylinder pressure. The wheel cylinder pressure is maintained at the master cylinder pressure equivalent value Pw1 (S24). Specifically, similarly to t2 to t3 in FIG. 4, the gate-in valve 2p and the gate-out valve 1p are closed, and the opening degree of the pressure reducing control valve 8a is proportionally controlled (maintained at a predetermined opening degree). Since the brake fluid circulates in the closed passage, no brake fluid is supplied to the wheel cylinder 5a, and no brake fluid is stored in the internal reservoir 15p. Therefore, the wheel cylinder pressure is maintained at the target value Pw1, and the reservoir fluid amount does not change. Also, the pedal stroke is kept constant.

  At t24, the driver starts to depress the brake pedal BP, and until t26, the brake pedal BP is depressed. That is, the treading force (pedal pressing force) decreases from t24 to t26, and thereby the master cylinder pressure (detected value) decreases. Therefore, predetermined wheel cylinder pressure control is executed from t24 to t26 (S18 to S24). Incidentally, the pedal stroke is reduced and the master cylinder pressure is smoothly reduced by the well-known cup seal structure of the master cylinder M / C that adjusts the communication between the external reservoir RES and the hydraulic chamber of the master cylinder M / C.

  From t24 to t25, the master cylinder pressure (detected value) is higher than the holding pressure Pw0. For this reason, the wheel cylinder pressure target value is (re) set in accordance with the decrease in the master cylinder pressure so that the wheel cylinder pressure becomes a value corresponding to the master cylinder pressure. Therefore, the wheel cylinder pressure is reduced so as to coincide with the target value that decreases (S22, S23). Specifically, the opening degree of the pressure reducing control valve 8a is increased by proportional control while the gate-in valve 2 and the gate-out valve 1 are closed. As a result, the brake fluid circulates in the closed passage, and the brake fluid in the wheel cylinder 5a is discharged to the internal reservoir 15p through the decompression control valve 8a, increasing the reservoir fluid amount and reducing the wheel cylinder pressure.

  At t25, the master cylinder pressure (detected value) = the wheel cylinder pressure decreases to the holding pressure Pw0. From t25 to t26, the master cylinder pressure (detected value) is equal to or lower than the holding pressure Pw0, so the holding pressure Pw0 is maintained as the wheel cylinder pressure target value, and the wheel cylinder pressure is held at the holding pressure Pw0 (S24). While the brake fluid circulates in the closed passage, the brake fluid is not supplied to or discharged from the wheel cylinder 5a and the internal reservoir 15p.

  At t26, the driver depresses the brake pedal BP, and the pedal stroke and master cylinder pressure are reduced to zero. After t26, since the driver does not operate the brake pedal, the wheel cylinder pressure control in ACC is continued (S12). Specifically, the wheel cylinder pressure is held at a target value (holding pressure Pw0) in ACC (S7). t3 to t4 are the same as in FIG. 4 (S5, S17).

(Effect of Example 1 in contrast with a comparative example)
As a comparative example, consider an apparatus that can execute automatic brake control by using a hydraulic unit HU (FIG. 1) similar to that of the first embodiment and does not perform the stepping prevention control as in the first embodiment. . In the comparative example, when the brake pedal BP is depressed by the driver while the automatic brake control is being executed (for example, when the gate cylinder valve 1 is closed and the wheel cylinder pressure is reduced or maintained), the brake pedal BP is provided in parallel with the gate-out valve 1. The brake fluid from the master cylinder M / C is supplied to the wheel cylinder 5 via the check valve 3. The check valve 3 opens when the master cylinder pressure exceeds the wheel cylinder pressure, and allows the brake fluid to flow. Thereby, the displacement (stroke) of the brake pedal BP and the increase of the wheel cylinder pressure according to the increase of the master cylinder pressure can be made to a certain extent. However, this device cannot sufficiently improve the driver's brake operation feeling as described below.

  FIG. 7 is a time chart (only wheel wheel pressure, master cylinder pressure, and pedal stroke changes are shown) when a brake operation is performed during automatic brake control (maintaining wheel cylinder pressure in ACC), as in FIG. The change of the pedal stroke is shown in comparison with the first embodiment and the comparative example.

  As shown in FIG. 7, in the comparative example, the master cylinder pressure rises to the wheel cylinder pressure (target value in ACC = holding pressure Pw0) after t21 when the master cylinder pressure is generated by the driver's depression of the brake pedal BP. Since the brake fluid cannot be supplied from the master cylinder M / C to the wheel cylinder 5 via the check valve 3, the stroke of the brake pedal BP is impossible. The time t22 at which the pedal stroke is possible is later than the pedal depression start time t21 by the driver.

  Therefore, from the time when the operating force (master cylinder pressure) starts to increase until the pedal stroke becomes possible, a feeling of “hardness” (a feeling of stepping on the brake pedal) occurs in the initial stage of the brake operation. Further, even if the same wheel cylinder pressure is generated by the delay, the pedal stroke for that is reduced. As described above, in the comparative example, the brake pedal BP does not operate (stroke) as intended by the driver, so that the driver may feel uncomfortable and the brake operation feeling cannot be sufficiently improved.

  In the comparative example, when an increase in the brake pedal BP is detected during automatic brake control, the pressure is reduced (with the gate-out valve 1 closed and the master cylinder M / C and the suction side of the pump P are not in communication). It is also conceivable to accelerate the stroke of the brake pedal BP by opening the control valve 8. That is, when the pressure reducing control valve 8 is opened, the brake fluid in the wheel cylinder 5 is drawn into the internal reservoir 15 and the wheel cylinder pressure (the fluid pressure downstream of the check valve 3) is lowered. For this reason, it becomes easy for the master cylinder pressure (the hydraulic pressure upstream of the check valve 3) to exceed the wheel cylinder pressure. That is, the brake fluid delivered from the master cylinder M / C can easily move through the check valve 3, and the time when the stroke of the brake pedal BP becomes possible is advanced.

  However, even in this case, the check valve 3 is not opened until the master cylinder pressure exceeds the wheel cylinder pressure, and therefore the brake pedal BP cannot be stroked. Therefore, the problem that the “hardness” (stepping feeling) in the initial depression of the brake pedal BP occurs cannot be solved. In addition, since the wheel cylinder pressure needs to be once lower than the control target (holding pressure Pw0), there is a trade-off between the wheel cylinder pressure control and the improvement of the brake operation feeling, and there is a risk that these cannot be optimally achieved. There is.

  On the other hand, in the first embodiment, the brake fluid from the master cylinder M / C is sucked by the pump P according to the driver's brake operation, so that the master cylinder pressure increases (the brake pedal BP is depressed). (Increase) Pedal stroke is possible almost simultaneously with the start time t21. That is, the pedal stroke starts to increase immediately before t22 when the master cylinder pressure increases to the wheel cylinder pressure (holding pressure Pw0) and immediately after t21 when the brake operation force (master cylinder pressure) starts to increase. Therefore, it is possible to prevent the driver from feeling a stepping stone.

  Further, since the start of the pedal stroke is not delayed with respect to the start of the brake operation (depressing the pedal), even if the same wheel cylinder pressure is generated, the pedal stroke for that purpose is not reduced. In other words, the relationship between the pedal stroke and the wheel cylinder pressure has the same characteristics as during normal braking. Therefore, it is possible to achieve a pedal stroke similar to that during normal braking in combination with the suppression of the feeling of stepping on the foot, and to generate a good pedal feeling as intended by the driver.

  Further, since brake fluid from the master cylinder M / C sucked by the pump P can be stored in the internal reservoir 15 via the pressure reducing passage 13 and the like, the control of the wheel cylinder pressure is not greatly affected. For example, even if the stepping prevention control according to the first embodiment is executed while the wheel cylinder pressure is maintained, if all the brake fluid from the master cylinder M / C is stored in the internal reservoir 15, the brake fluid supplied to the wheel cylinder 5 is retained. Since the amount remains unchanged, the wheel cylinder pressure does not fluctuate. That is, there is no trade-off relationship between stone-step prevention control (improvement of brake operation feeling) and wheel cylinder pressure control, and both can be achieved.

  As described above, in the first embodiment, when the brake operation is performed during the automatic brake control, the internal reservoir 15 absorbs the brake fluid from the master cylinder M / C. The simulator functions are being demonstrated. Here, the stroke simulator is for generating a stroke or reaction force corresponding to the brake operation on the brake operation member (brake pedal BP) even when the passage connecting the master cylinder M / C and the wheel cylinder 5 is blocked. A member, such as a reservoir, is composed of a piston that can move while receiving the force of a spring. Further, it is usual to provide a cut valve capable of blocking communication between the stroke simulator and the master cylinder M / C in the input passage to the stroke simulator.

  In the apparatus according to the first embodiment, when a brake operation is performed during the automatic brake control, the internal reservoir 15 conventionally provided in the hydraulic unit also functions as a stroke simulator. For this reason, without adding parts such as a stroke simulator (new reservoir) or a cut valve, the automatic brake control is continued while the automatic brake control is continued (with the communication between the master cylinder M / C and the wheel cylinder 5 cut off). Operation feeling can be generated. In other words, like a brake control device with a stroke simulator, automatic brake control (for example, regenerative cooperative control in a hybrid vehicle) can be performed while ensuring a brake operation feeling, and no additional parts such as a stroke simulator are required. Therefore, the system can be simplified and the apparatus can be downsized.

  On the other hand, since the booster BS is provided in the first embodiment, even when the automatic brake control system (pump P or the like) fails, the desired wheel cylinder pressure (control) according to the driver's brake operation is reduced. Power) can be generated, and the reliability of the brake control device is high.

[Effect of Example 1]
Hereinafter, effects of the brake control device according to the first embodiment will be listed.
(1) The device of the first embodiment is provided in the master cylinder M / C and the wheels FL to RR that generate hydraulic pressure (master cylinder pressure) according to the operation of the brake operation member by the driver, and generates brake hydraulic pressure. The hydraulic unit HU provided between the wheel cylinder 5 and the operating force increase detecting means for detecting an increase in the force by which the driver operates the brake operating member is provided. A first passage 10 in which a gate-out valve 1 is provided, and a master cylinder M / C and a wheel cylinder 5 communicate with each other. The master cylinder M / C and the wheel cylinder 5 communicate with each other, the second passage (intake passage 11 and discharge passage 12) provided with the pump P, the wheel cylinder 5 and the reservoir (internal reservoir 15) communicate with each other, and the pressure is reduced. valve A decompression passage 13 provided with a (decompression control valve 8), a scraping passage 14 communicating the reservoir (internal reservoir 15) and the suction side of the pump P, and between the master cylinder M / C and the pump P in the second passage. It has a gate-in valve 2 provided and a control unit CU that controls the operation of the pump P and each of the valves 1, 2, and 8. Then, the pump P is driven, the gate-out valve 1 is closed, and the gate-in valve 2 and the pressure reducing valve are opened.

  Specifically, the brake operation member is a brake pedal BP, and the operation force increase detection means is an increase detection means (master cylinder pressure sensor 20) that detects an increase in the brake pedal BP by the driver. The HU includes a pump P that can automatically pressurize the wheel cylinder 5, a reservoir (internal reservoir 15) that can store brake fluid, a first passage 10 that communicates the master cylinder M / C and the wheel cylinder 5, and a master cylinder. A suction passage 11 that communicates the suction side of the M / C and the pump P, a discharge passage 12 that communicates the discharge side of the pump P and the wheel cylinder 5, and a decompression passage 13 that communicates the wheel cylinder 5 and the reservoir (internal reservoir 15). A scraping passage 14 that communicates the reservoir (internal reservoir 15) and the suction side of the pump P, a gate-out valve 1 disposed on the first passage 10, and a suction passage The fluid in the wheel cylinder 5 is controlled by controlling the gate-in valve 2 disposed on the pressure reducing valve 11, the pressure reducing valve (pressure reducing control valve 8) disposed on the pressure reducing passage 13, and the pump P and the valves 1, 2 and 8. A control unit CU for controlling the pressure, and the control unit CU drives the pump P when an increase in the brake pedal BP is detected by the additional step detection means while controlling the hydraulic pressure in the wheel cylinder 5. The gate-out valve 1 is closed, the gate-in valve 2 is opened, the opening degree of the pressure reducing valve is controlled, the hydraulic pressure in the wheel cylinder 5 is controlled to the target value, and the brake fluid from the master cylinder M / C is stored in the reservoir. It was decided to store in (internal reservoir 15).

  Therefore, even when the driver performs a brake operation during the control of the wheel cylinder pressure, the same pedal stroke as that during normal braking can be realized. Therefore, it is possible to prevent the driver from feeling a stepping stone and to improve the brake operation feeling. Further, additional parts such as a stroke simulator are unnecessary, and the apparatus can be miniaturized.

  (2) When the increase in operating force is detected by the operating force increase detection means (specifically, when the increase in the brake pedal BP is detected by the increase detection means), the control unit CU detects the gate-in valve 2 The hydraulic pressure on the pump suction side was controlled by controlling the opening degree.

  Therefore, the suction of the brake fluid from the master cylinder M / C by the pump P is smoothly performed, so that the effect (1) can be further improved.

  (3) The control unit CU closes the gate-out valve 1 and the gate-in valve 2 during the brake fluid pressure retention control (while maintaining the wheel cylinder pressure at the target value), drives the pump P, and The brake fluid is recirculated in the closed passage formed by the two passages (discharge passage 12), the decompression passage 13, and the scraping passage 14.

  Therefore, even when the driver depresses the brake pedal BP during the holding control, the brake fluid is recirculated in the closed passage, and the brake fluid discharged from the master cylinder M / C is sucked and sucked by the pump P. By releasing the minute amount of brake fluid to the internal reservoir 15, the brake pedal BP can be stroked without a stepping feeling while maintaining the brake fluid pressure at a desired value.

  (4) The hydraulic pressure generated by the master cylinder M / C is increased by the booster BS connected to the brake operation member (brake pedal BP).

  Therefore, the reliability of the brake control device at the time of failure can be improved.

[Other embodiments]
The best mode for carrying out the present invention has been described based on the first embodiment. However, the specific configuration of the present invention is not limited to the first embodiment and does not depart from the gist of the present invention. Any changes in the design of the range are included in the present invention.

  For example, in the first embodiment, the master cylinder pressure sensor is used as the operation force increase detection means for detecting the increase in the brake operation force of the driver, but a pedal depression force sensor or the like may be used.

  In the first embodiment, when the increase in the brake operation force (master cylinder pressure) is detected, the stepping prevention control is performed immediately after the increase is detected. The prevention control may be started.

  In the first embodiment, the stone-step prevention control is executed only when the brake operation is performed during the automatic brake control. However, the present invention is not limited to this case. The stepping prevention control may be executed in accordance with the brake operation. In this case, the wheel cylinder pressure can be adjusted freely without additional components such as a stroke simulator while ensuring operational feeling. For example, cooperative control between the regenerative braking force and the hydraulic braking force of the wheel cylinder can be executed. It becomes.

  In the first embodiment, the booster BS is provided. However, the booster is omitted, and a desired wheel cylinder pressure corresponding to the (detected) brake operating force is supplied to the pump or the like even during normal braking. It is good also as generating by. In this case, an appropriate operational feeling can be ensured by executing the stone step prevention control.

  In the first embodiment, proportional control valves are used for the gate-out valve 1 and the pressure reducing control valve 8, but duty control may be performed using an on / off control valve having a simpler configuration. Further, in the first embodiment, the on / off control valve is used for the gate-in valve 2 and the pressure increase control valve 6, but it is also possible to use a proportional control valve with better control accuracy.

  In the first embodiment, a servo motor with excellent controllability is used as a pump drive source. However, a drive source such as an internal combustion engine may be used.

  In the first embodiment, on the premise that the motor M is on / off controlled and the pressure reducing control valve 8 is proportionally controlled, the opening degree (leakage amount) of the pressure reducing control valve 8 is proportionally controlled while the motor M is on. Thus, the amount of brake fluid supplied to or discharged from the wheel cylinder is adjusted, but the rotation speed of the motor M (pump discharge amount) is proportionally controlled while the pressure reducing control valve 8 is fixed at a predetermined opening. It is good also as adjusting the amount of liquid supply / drain to a wheel cylinder.

  In the first embodiment, the amount of reduction in the wheel cylinder pressure is adjusted by proportionally controlling the opening degree of the gate-out valve 1 (when there is no brake operation during automatic brake control). As in the case where the brake operation is performed, the amount of reduction in the wheel cylinder pressure may be adjusted by proportionally controlling the opening of the pressure reducing control valve 8.

  In the first embodiment, the brake control device of the present invention is applied to a four-wheeled vehicle, but may be applied to a two-wheeled vehicle. For example, a motorcycle having a brake circuit configuration similar to that of one piping system of the hydraulic unit HU in FIG. 1 or a brake circuit configuration having one wheel in each system of the hydraulic unit HU in FIG. The present invention can also be applied to a motorcycle equipped with a vehicle that can execute automatic brake control and the like.

1 Gate-out valve 2 Gate-in valve 5 Wheel cylinder 8 Pressure reduction control valve (pressure reduction valve)
10 First passage 11 Suction passage (second passage)
12 Discharge passage (second passage)
13 Decompression passage 14 Scraping passage 15 Internal reservoir (reservoir)
20 Master cylinder pressure sensor (operation force increase detection means, stepping increase detection means)
BP Brake pedal (brake operating member)
M / C Master cylinder FL to RR Wheel HU Hydraulic unit P Pump CU Control unit

Claims (8)

A hydraulic unit provided between a master cylinder that generates hydraulic pressure in response to an operation of a brake operation member by a driver and a wheel cylinder that is provided on a wheel and generates brake hydraulic pressure;
An operation force increase detection means for detecting an increase in force with which the driver operates the brake operation member, and
The hydraulic unit is
A reservoir capable of storing brake fluid;
A pump for supplying discharge pressure to the wheel cylinder;
A first passage that communicates the master cylinder and the wheel cylinder and is provided with a gate-out valve;
A second passage in which the master cylinder and the wheel cylinder communicate with each other, and the pump is provided;
A pressure reducing passage that communicates the wheel cylinder and the reservoir and is provided with a pressure reducing valve;
A scraping passage communicating the reservoir and the suction side of the pump;
A gate-in valve provided between the master cylinder and the pump in the second passage;
A control unit for controlling the operation of the pump and the valves,
The control unit drives the pump, closes the gate-out valve, and opens the gate-in valve and the pressure-reducing valve when an increase in operating force is detected by the operating force increase detection means. Brake control device. The brake control device according to claim 1, wherein
The control unit is configured to control a hydraulic pressure on a suction side of the pump by controlling an opening degree of the gate-in valve when an increase in the operation force is detected by the operation force increase detection unit. Control device. The brake control device according to claim 1 or 2,
The control unit closes the gate-out valve and the gate-in valve during the brake fluid pressure holding control, drives the pump, the second passage on the discharge side of the pump, the pressure reducing passage, and the scraping passage. A brake control device that recirculates brake fluid in a closed passage formed by In the brake control device according to any one of claims 1 to 3,
The hydraulic pressure generated by the master cylinder is increased by a booster connected to the brake operation member. A hydraulic unit provided between a master cylinder that generates brake pressure in response to an operation of a brake pedal by a driver and a wheel cylinder provided on a wheel;
A stepping detection means for detecting a stepping on the brake pedal by the driver,
The hydraulic unit is
A pump capable of automatically pressurizing the wheel cylinder;
A reservoir capable of storing brake fluid;
A first passage communicating the master cylinder and the wheel cylinder;
A suction passage communicating the master cylinder and the suction side of the pump;
A discharge passage communicating the discharge side of the pump and the wheel cylinder;
A decompression passage communicating the wheel cylinder and the reservoir;
A scraping passage communicating the reservoir and the suction side of the pump;
A gate-out valve disposed on the first passage;
A gate-in valve disposed on the suction passage;
A pressure reducing valve disposed on the pressure reducing passage;
A control unit that controls the hydraulic pressure of the wheel cylinder by controlling the pump and the valves;
The control unit drives the pump, closes the gate-out valve, and closes the gate-in valve when the increase in the brake pedal is detected by the step-up detection means while controlling the hydraulic pressure of the wheel cylinder. And controlling the opening of the pressure reducing valve to control the hydraulic pressure of the wheel cylinder to a target value, and storing the brake fluid from the master cylinder in the reservoir. The brake control device according to claim 5,
The control unit is configured to control the hydraulic pressure on the suction side of the pump by controlling the opening of the gate-in valve when the increase in the brake pedal is detected by the increase detection means. Brake control device. The brake control device according to claim 5 or 6,
The control unit closes the gate-out valve and the gate-in valve during the control to maintain the hydraulic pressure of the wheel cylinder at a target value, drives the pump, and discharges, decompresses, and scrapes. A brake control device that recirculates brake fluid in a closed passage formed by In the brake control device according to any one of claims 5 to 7,
The hydraulic pressure generated by the master cylinder is boosted by a booster connected to the brake pedal.

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