JP6781580B2 - Vehicle braking device - Google Patents

Description

The present invention relates to a vehicle braking device.

Some vehicle braking devices perform traction control to generate braking force on the wheels regardless of the braking operation when the wheels slip when the vehicle is accelerating (for example, when starting). In the vehicle braking device, for example, a braking force is generated on a target wheel so that a predetermined slip ratio is maintained (see Patent Document 1). Further, as a braking device for a vehicle, a master cylinder having a master chamber in which a master hydraulic pressure is generated by driving a master piston, a driving hydraulic chamber for generating a driving hydraulic pressure for driving the master piston, and a driving hydraulic chamber. It is known that a valve portion for adjusting the inflow and outflow of fluid with respect to the valve portion and a hydraulic pressure control unit for controlling the valve portion are provided. The hydraulic pressure control unit sets a target pressure, which is a target value of the driving hydraulic pressure, and sets a range from a low pressure side threshold value lower than the target pressure to a high pressure side threshold value higher than the target pressure as a dead zone, and actually drives the hydraulic pressure. When the actual pressure, which is the value, is a value outside the dead zone, the valve portion is controlled so that the actual pressure approaches the target pressure, and when the actual pressure is a value inside the dead zone, the actual pressure is applied to the valve portion. Executes the retention control to retain.

Further, in the traction control in the vehicle braking device, a high-pressure master hydraulic pressure is generated by the valve portion, and the hydraulic pressure of each wheel cylinder (wheel liquid) is generated by an actuator provided between the master chamber and the plurality of wheel cylinders. Pressure) is controlled.

Japanese Unexamined Patent Publication No. 2008-296828

In such traction control, if the differential pressure between the master hydraulic pressure and the wheel hydraulic pressure is large, the operating noise (oil impact sound) in the actuator becomes loud, so the master hydraulic pressure is controlled so that the differential pressure becomes small. Is possible. In this way, it is conceivable that the master hydraulic pressure is controlled by the valve portion even during traction control. However, if the master hydraulic pressure is controlled by the valve portion during traction control, the operation frequency of the valve portion (control switching frequency) increases.

The vehicle braking device of the present invention includes a master cylinder having a master chamber in which a master hydraulic pressure is generated by driving a master piston, a driving hydraulic chamber for generating a driving hydraulic pressure for driving the master piston, and the driving liquid. A valve portion that adjusts the inflow and outflow of fluid to the pressure chamber and a target pressure, which is a target value of the driving fluid pressure, are set, and a low pressure side threshold lower than the target pressure to a high pressure side threshold value higher than the target pressure are set. When the actual pressure, which is the actual value of the driving hydraulic pressure, is a value outside the dead zone, the valve portion is controlled so that the actual pressure approaches the target pressure, and the actual pressure becomes the said. When the value is within the dead zone, the hydraulic pressure control unit that controls the valve portion to maintain the actual pressure and the hydraulic passage connecting the master chamber and the wheel cylinder are provided from the master chamber. An actuator that adjusts the outflow of fluid to the wheel cylinder, a traction control unit that executes traction control that suppresses slippage during acceleration of the vehicle by controlling the actuator, and the dead zone according to the control state of the traction control. It is equipped with a dead zone setting unit that expands the width of the wheel. In the vehicle braking device of the first aspect, the dead zone setting unit sets the first low pressure side threshold value as the low pressure side threshold value from the start of the traction control until a predetermined condition is satisfied, and in the traction control. After the predetermined condition is satisfied, a second low pressure side threshold value lower than the first low pressure side threshold value is set as the low pressure side threshold value, and the predetermined condition elapses a predetermined time from the start of the traction control. This includes the fact that the slip ratio of the slip is less than the predetermined value, or that a predetermined time has elapsed since the traction control was started and the slip ratio of the slip is less than the predetermined value. In the vehicle braking device of the second aspect, the actuator is the first solenoid valve provided in the hydraulic path, the second solenoid valve provided between the wheel cylinder and the reservoir, and the inside of the reservoir. It has a pump that discharges fluid to a portion of the hydraulic path on the master chamber side of the first solenoid valve, and the dead zone setting unit sets a first high pressure side threshold when the traction control is started. It is set as the high pressure side threshold, and when the pump operates in the traction control, a second high pressure side threshold higher than the first high pressure side threshold is set as the high pressure side threshold.

The vehicle braking device of the present invention includes a master cylinder having a master chamber in which a master hydraulic pressure is generated by driving a master piston, a driving hydraulic chamber for generating a driving hydraulic pressure for driving the master piston, and the driving liquid. A valve portion that adjusts the inflow and outflow of fluid to the pressure chamber and a target pressure, which is a target value of the driving fluid pressure, are set, and a low pressure side threshold lower than the target pressure to a high pressure side threshold value higher than the target pressure are set. When the actual pressure, which is the actual value of the driving hydraulic pressure, is a value outside the dead zone, the valve portion is controlled so that the actual pressure approaches the target pressure, and the actual pressure becomes the said. When the value is within the dead zone, the hydraulic pressure control unit that controls the valve portion to maintain the actual pressure and the hydraulic passage connecting the master chamber and the wheel cylinder are provided from the master chamber. An actuator that adjusts the outflow of fluid to the wheel cylinder, a traction control unit that executes traction control that suppresses slippage during acceleration of the vehicle by controlling the actuator, and the dead zone according to the control state of the traction control. It is equipped with a dead zone setting unit that expands the width of the wheel.

According to the present invention, by expanding the width of the dead zone with respect to the target pressure of the driving hydraulic pressure during traction control (hereinafter referred to as "expanding the dead zone width"), the number of times the valve portion is operated can be reduced, and eventually the valve portion can be operated. Durability can be improved. By expanding the dead zone width according to the control state of the traction control, it is possible to suppress a decrease in the accuracy of the traction control due to the increase in the dead zone width. That is, according to the present invention, it is possible to improve the durability of the valve portion while suppressing a decrease in the accuracy of traction control.

It is a block diagram which shows the structure of the vehicle braking device of this embodiment. It is a time chart for demonstrating the correction control of this embodiment. It is a flowchart for demonstrating the correction control of this embodiment.

Hereinafter, an embodiment in which the vehicle device according to the present invention is applied to a vehicle will be described with reference to the drawings. The vehicle directly applies a hydraulic braking force to each wheel Wfl, Wfr, Wrl, Wrr (hereinafter, also referred to as wheels W, front wheels Wf, and rear wheels Wr in the collective expression) to brake the vehicle. I have.

(overall structure)
As shown in FIG. 1, the vehicle braking device A includes a brake pedal 11, a master cylinder 12, a stroke simulator unit 13, a reservoir 14, a boosting mechanism (corresponding to a “valve portion”) 15, an actuator 16, and a brake ECU ( It includes 17 (corresponding to a "control unit") and a wheel cylinder WC.

The wheel cylinders WCfl, WCfr, WCrl, and WCrr (hereinafter, collectively referred to as wheel cylinders WC) regulate the rotation of the wheel W, and are provided in each caliper CL. The wheel cylinder WC is a braking force applying mechanism that applies a braking force to the wheels W of the vehicle based on the pressure (brake fluid pressure) of the brake fluid (corresponding to "fluid") from the actuator 16. When brake hydraulic pressure is supplied to the wheel cylinder WC, each piston of the wheel cylinder WC (not shown) presses a pair of brake pads (not shown), which are friction members, and is a rotating member that rotates integrally with the wheel W. The disc rotor DR is sandwiched from both sides to regulate its rotation. In this embodiment, the disc type brake is adopted, but the drum type brake may be adopted.

The brake pedal 11 is a brake operating member and is connected to the stroke simulator unit 13 and the master cylinder 12 via the operating rod 11a.
A stroke sensor 11c is provided in the vicinity of the brake pedal 11 to detect a brake pedal stroke (operation amount: hereinafter, may be referred to as a stroke), which is a state in which the brake is operated by depressing the brake pedal 11. The stroke sensor 11c is connected to the brake ECU 17, and a detection signal (detection result) is output to the brake ECU 17.

The master cylinder 12 supplies brake fluid to the actuator 16 according to the amount of operation of the brake pedal 11, and is composed of a cylinder body 12a, an input piston 12b, a first master piston 12c, a second master piston 12d, and the like. ing.

The cylinder body 12a is formed in a substantially cylindrical shape with a bottom. A partition wall portion 12a2 protruding inwardly into a flange shape is provided on the inner peripheral portion of the cylinder body 12a. A through hole 12a3 penetrating in the front-rear direction is formed in the center of the partition wall portion 12a2. A first master piston 12c and a second master piston 12d are arranged on the inner peripheral portion of the cylinder body 12a in a portion in front of the partition wall portion 12a2 so as to be liquid-tight and movable along the axial direction.

An input piston 12b is provided on the inner peripheral portion of the cylinder body 12a in a portion rearward from the partition wall portion 12a2 so as to be liquid-tight and movable along the axial direction. The input piston 12b is a piston that slides in the cylinder body 12a in response to the operation of the brake pedal 11.

An operation rod 11a linked to the brake pedal 11 is connected to the input piston 12b. The input piston 12b is urged by the compression spring 11b in the direction in which the first hydraulic chamber R3 is expanded, that is, in the rearward direction (to the right in the drawing). When the brake pedal 11 is depressed, the operating rod 11a advances against the urging force of the compression spring 11b. As the operation rod 11a advances, the input piston 12b also advances in conjunction with it. When the stepping operation of the brake pedal 11 is released, the input piston 12b retracts due to the urging force of the compression spring 11b and is positioned in contact with the regulation convex portion 12a4.

The first master piston 12c is formed by integrally forming a pressure cylinder portion 12c1, a flange portion 12c2, and a protruding portion 12c3 in order from the front side. The pressure cylinder portion 12c1 is formed in a substantially cylindrical shape with a bottom having an opening at the front, and is arranged liquid-tightly and slidably with the inner peripheral surface of the cylinder body 12a. In the internal space of the pressurizing cylinder portion 12c1, a coil spring 12c4 which is an urging member is arranged between the pressure cylinder portion 12c1 and the second master piston 12d. The first master piston 12c is urged rearward by the coil spring 12c4. In other words, the first master piston 12c is urged rearward by the coil spring 12c4 and is finally positioned in contact with the regulation convex portion 12a5. This position is the original position (preset) when the depressing operation of the brake pedal 11 is released.

The flange portion 12c2 is formed to have a larger diameter than the pressure cylinder portion 12c1, and is liquidtightly and slidably arranged on the inner peripheral surface of the large diameter portion 12a6 in the cylinder body 12a. The protruding portion 12c3 is formed to have a smaller diameter than the pressure cylinder portion 12c1, and is arranged so as to slide liquid-tightly in the through hole 12a3 of the partition wall portion 12a2. The rear end portion of the projecting portion 12c3 passes through the through hole 12a3, projects into the internal space of the cylinder body 12a, and is separated from the inner peripheral surface of the cylinder body 12a. The rear end surface of the protrusion 12c3 is separated from the bottom surface of the input piston 12b, and the separation distance is configured to be variable.

The second master piston 12d is arranged on the front side of the first master piston 12c in the cylinder body 12a. The second master piston 12d is formed in a substantially cylindrical shape with a bottom having an opening at the front. In the internal space of the second master piston 12d, a coil spring coil 12d1 which is an urging member is arranged between the inner bottom surface of the cylinder body 12a. The second master piston 12d is urged rearward by the coil spring 12d1. In other words, the second master piston 12d is urged by the coil spring 12d1 toward the set in-situ position.

Further, the master cylinder 12 is formed with a first master chamber R1, a second master chamber R2, a first hydraulic chamber R3, a second hydraulic chamber R4, and a servo chamber R5. In the description, the first master room R1 and the second master room R2 may be collectively referred to as master rooms R1 and R2. The first master chamber R1 is partitioned by the inner peripheral surface of the cylinder body 12a, the first master piston 12c (the front side of the pressurized cylinder portion 12c1), and the second master piston 12d. The first master chamber R1 is connected to the reservoir 14 via an oil passage 21 connected to the port PT4. Further, the first master chamber R1 is connected to the oil passage 40a (actuator 16) via the oil passage 22 connected to the port PT5.

The second master chamber R2 is partitioned by the inner peripheral surface of the cylinder body 12a and the front side of the second master piston 12d. The second master chamber R2 is connected to the reservoir 14 via an oil passage 23 connected to the port PT6. Further, the second master chamber R2 is connected to the oil passage 50a (actuator 16) via the oil passage 24 connected to the port PT7.

The first hydraulic chamber R3 is formed between the partition wall portion 12a2 and the input piston 12b, and includes the inner peripheral surface of the cylinder body 12a, the partition wall portion 12a2, the protruding portion 12c3 of the first master piston 12c, and the input piston 12b. It is partitioned by. The second hydraulic chamber R4 is formed on the side of the pressure cylinder portion 12c1 of the first master piston 12c, and is the inner peripheral surface of the large diameter portion 12a6 of the inner peripheral surface of the cylinder body 12a and the pressure cylinder portion 12c1. , And a flange portion 12c2. The first hydraulic chamber R3 is connected to the second hydraulic chamber R4 via the oil passage 25 connected to the port PT1 and the port PT3.

The servo chamber R5 is formed between the partition wall portion 12a2 and the pressure cylinder portion 12c1 of the first master piston 12c, and is formed on the inner peripheral surface of the cylinder body 12a, the partition wall portion 12a2, and the protruding portion 12c3 of the first master piston 12c. , And a pressure cylinder portion 12c1. The servo chamber R5 is connected to the output chamber R12 via an oil passage 26 connected to the port PT2.

The pressure sensor 26a is a sensor that detects the servo pressure (corresponding to the "driving hydraulic pressure") supplied to the servo chamber (corresponding to the "hydraulic chamber") R5, and is connected to the oil passage 26. The pressure sensor 26a transmits a detection signal (detection result) to the brake ECU 17. The servo pressure detected by the pressure sensor 26a is an actual value of the hydraulic pressure of the servo chamber R5, and is hereinafter referred to as an actual servo pressure (corresponding to "actual pressure").

The stroke simulator unit 13 includes a cylinder body 12a, an input piston 12b, a first hydraulic chamber R3, and a stroke simulator 13a communicating with the first hydraulic chamber R3.
The first hydraulic chamber R3 communicates with the stroke simulator 13a via the oil passages 25 and 27 connected to the port PT1. The first hydraulic pressure chamber R3 communicates with the reservoir 14 via a connecting oil passage (not shown).

The stroke simulator 13a generates a stroke (reaction force) of a size corresponding to the operating state of the brake pedal 11 on the brake pedal 11. The stroke simulator 13a includes a cylinder portion 13a1, a piston portion 13a2, a reaction force hydraulic chamber 13a3, and a spring 13a4. The piston portion 13a2 slides in the cylinder portion 13a1 in a liquid-tight manner as the brake is operated to operate the brake pedal 11. The reaction force hydraulic chamber 13a3 is formed so as to be partitioned between the cylinder portion 13a1 and the piston portion 13a2. The reaction force hydraulic chamber 13a3 communicates with the first hydraulic chamber R3 and the second hydraulic chamber R4 via the connected oil passages 27 and 25. The spring 13a4 urges the piston portion 13a2 in a direction that reduces the volume of the reaction force hydraulic chamber 13a3.

The oil passage 25 is provided with a first solenoid valve 25a, which is a normally closed type solenoid valve. A second solenoid valve 28a, which is a normally open type solenoid valve, is provided in the oil passage 28 connecting the oil passage 25 and the reservoir 14. When the first solenoid valve 25a is closed, the first hydraulic chamber R3 and the second hydraulic chamber R4 are shut off. As a result, the input piston 12b and the first master piston 12c are interlocked with each other while maintaining a constant separation distance. Further, when the first solenoid valve 25a is in the open state, the first hydraulic chamber R3 and the second hydraulic chamber R4 are communicated with each other. As a result, the volume change of the first hydraulic chamber R3 and the second hydraulic chamber R4 accompanying the advance / retreat of the first master piston 12c is absorbed by the movement of the brake fluid.

The pressure sensor 25b is a sensor that detects the reaction force hydraulic pressure of the second hydraulic chamber R4 and the first hydraulic chamber R3, and is connected to the oil passage 25. The pressure sensor 25b is also an operating force sensor that detects an operating force on the brake pedal 11, and has an interrelationship with the operating amount of the brake pedal 11. The pressure sensor 25b detects the pressure in the second hydraulic chamber R4 when the first solenoid valve 25a is in the closed state, and communicates with the first hydraulic chamber R3 when the first solenoid valve 25a is in the open state. Pressure (or reaction force hydraulic pressure) will also be detected. The pressure sensor 25b transmits a detection signal (detection result) to the brake ECU 17.

The booster mechanism 15 generates a servo pressure according to the amount of operation of the brake pedal 11. The booster mechanism 15 is a hydraulic pressure generator that outputs an output pressure (servo pressure in the present embodiment) by the action of an input input pressure (pilot pressure in the present embodiment), and increases or decreases the output pressure. This is a hydraulic pressure generator in which a response delay of the output pressure occurs with respect to the input pressure at the beginning of the pressure increase or the start of the depressurization. The booster mechanism 15 includes a regulator 15a and a pressure supply device 15b.
The regulator 15a includes a cylinder body 15a1 and a spool 15a2 that slides in the cylinder body 15a1. A pilot chamber R11, an output chamber R12, and a third hydraulic pressure chamber R13 are formed in the regulator 15a.

The pilot chamber R11 is partitioned by the cylinder body 15a1 and the front end faces of the second large diameter portion 15a2b of the spool 15a2. The pilot chamber R11 is connected (to the oil passage 31) to the pressure reducing valve 15b6 and the pressure increasing valve 15b7 connected to the port PT11. Further, the inner peripheral surface of the cylinder body 15a1 is provided with a regulation convex portion 15a4 in which the front end surface of the second large diameter portion 15a2b of the spool 15a2 is in contact and positioned.

The output chamber R12 is partitioned by the cylinder body 15a1, the small diameter portion 15a2c of the spool 15a2, the rear end surface of the second large diameter portion 15a2b, and the front end surface of the first large diameter portion 15a2a. The output chamber R12 is connected to the servo chamber R5 of the master cylinder 12 via the oil passage 26 connected to the port PT12 and the port PT2. Further, the output chamber R12 can be connected to the accumulator 15b2 via the oil passage 32 connected to the port PT13.

The third hydraulic chamber R13 is partitioned by the cylinder body 15a1 and the rear end surface of the first large diameter portion 15a2a of the spool 15a2. The third hydraulic chamber R13 can be connected to the reservoir 15b1 via the oil passage 33 connected to the port PT14. Further, in the third hydraulic chamber R13, a spring 15a3 for urging the third hydraulic chamber R13 in the expanding direction is arranged.

The spool 15a2 includes a first large diameter portion 15a2a, a second large diameter portion 15a2b, and a small diameter portion 15a2c. The first large-diameter portion 15a2a and the second large-diameter portion 15a2b are configured to slide in the cylinder body 15a1 in a liquid-tight manner. The small diameter portion 15a2c is arranged between the first large diameter portion 15a2a and the second large diameter portion 15a2b, and is integrally formed with the first large diameter portion 15a2a and the second large diameter portion 15a2b. .. The small diameter portion 15a2c is formed to have a smaller diameter than the first large diameter portion 15a2a and the second large diameter portion 15a2b.
Further, the spool 15a2 is formed with a communication passage 15a5 that communicates the output chamber R12 and the third hydraulic pressure chamber R13.

The pressure supply device 15b is also a drive unit that drives the spool 15a2. The pressure supply device 15b sucks the reservoir 15b1 which is a low pressure source, the accumulator 15b2 which is a high pressure source and stores the brake fluid (corresponding to "fluid"), and the brake fluid of the reservoir 15b1 and pumps the brake fluid to the accumulator 15b2. It includes a pump 15b3 and an electric motor 15b4 for driving the pump 15b3. The reservoir 15b1 is open to the atmosphere, and the hydraulic pressure of the reservoir 15b1 is the same as the atmospheric pressure. The low pressure source is lower pressure than the high pressure source. The pressure supply device 15b includes a pressure sensor 15b5 that detects the pressure of the brake fluid supplied from the accumulator 15b2 and outputs the pressure to the brake ECU 17.

Further, the pressure supply device 15b includes a pressure reducing valve 15b6 and a pressure increasing valve 15b7. It can be said that the pressure reducing valve 15b6 and the pressure increasing valve 15b7 form a valve portion. Specifically, the pressure reducing valve 15b6 is a solenoid valve having a structure (normally open type) that opens in a non-energized state, and the flow rate is controlled by a command from the brake ECU 17. One of the pressure reducing valves 15b6 is connected to the pilot chamber R11 via the oil passage 31, and the other of the pressure reducing valves 15b6 is connected to the reservoir 15b1 via the oil passage 34. The pressure boosting valve 15b7 is a solenoid valve having a structure (normally closed type) that closes in a non-energized state, and the flow rate is controlled by a command from the brake ECU 17. One of the booster valves 15b7 is connected to the pilot chamber R11 via the oil passage 31, and the other of the booster valves 15b7 is connected to the accumulator 15b2 via the oil passage 35 and the oil passage 32 to which the oil passage 35 is connected. There is.

Here, the operation of the regulator 15a will be briefly described. When the pilot pressure (hydraulic pressure of the pilot chamber R11) is not supplied from the pressure reducing valve 15b6 and the pressure increasing valve 15b7 to the pilot chamber R11, the spool 15a2 is urged by the spring 15a3 and is in the original position (see FIG. 1). The original position of the spool 15a2 is a position where the front end surface of the spool 15a2 abuts on the regulation convex portion 15a4 and is positioned and fixed, and a position immediately before the rear end surface of the spool 15a2 closes the port PT14.
As described above, when the spool 15a2 is in the original position, the port PT14 and the port PT12 communicate with each other via the communication passage 15a5, and the port PT13 is blocked by the spool 15a2.

When the pressure reducing valve 15b6 and the pressure increasing valve 15b7 increase the pilot pressure formed according to the operation amount of the brake pedal 11, the spool 15a2 moves rearward (to the right in FIG. 1) against the urging force of the spring 15a3. Move towards. Then, the spool 15a2 moves to a position where the port PT13 blocked by the spool 15a2 is opened. Further, the opened port PT14 is closed by the spool 15a2. Further, the opened port PT14 is closed by the spool 15a2. The position of the spool valve 15a2 in this state is defined as the “pressure boosting position”. At this time, the rear end surface of the second large diameter portion 15a2b of the spool 15a2 receives a force corresponding to the servo pressure (when the pressure is increased).

Then, the spool 15a2 is positioned by balancing the pressing force on the front end surface of the second large diameter portion 15a2b of the spool 15a2 with the resultant force of the force corresponding to the servo pressure and the urging force of the spring 15a3. At this time, the position of the spool 15a2 is set as the "holding position". At the holding position, the port PT13 and the port PT14 are blocked by the spool 15a2 (during holding).

Further, when the pilot pressure formed by the pressure reducing valve 15b6 and the pressure increasing valve 15b7 according to the operation amount of the brake pedal 11 is reduced, the spool 15a2 in the holding position moves forward by the urging force of the spring 15a3. To do. Then, the port PT13 blocked by the spool 15a2 is maintained in the blocked state. Further, the blocked port PT14 is opened. The position of the spool valve 15a2 in this state is defined as the "decompression position". At this time, the port PT14 and the port PT12 communicate with each other via the communication passage 15a5 (during decompression).

In the boosting mechanism 15 described above, the pressure reducing valve 15b6 and the pressure boosting valve 15b7 form a pilot pressure according to the stroke of the brake pedal 11, and the pilot pressure generates a servo pressure corresponding to the stroke of the brake pedal 11. The generated servo pressure is supplied to the servo chamber R5 of the master cylinder 12, and the master cylinder 12 supplies the master hydraulic pressure generated according to the stroke of the brake pedal 11 to the wheel cylinder WC. The master hydraulic pressure is the pressure of the master chambers R1 and R2. The pressure reducing valve 15b6 and the pressure increasing valve 15b7 form a valve portion that regulates the inflow and outflow of the brake fluid to and from the servo chamber R5.

In this way, the booster mechanism 15 has a spool 15a2 (piston) driven by a force corresponding to the pilot pressure, which is the hydraulic pressure of the pilot chamber R11, and a direction in which the spool 15a2 is driven by a force corresponding to the pilot pressure. Has a spring 15a3 (a urging portion) for urging the spool 15a2 on the opposite side, and is configured to adjust the flow rate of the brake fluid to the servo chamber R5 by moving the spool 15a2, and an accumulator 15b2 ( It is provided with a pressure boosting valve 15b7 arranged between the high pressure source) and the pilot chamber R11, and a pressure reducing valve 15b6 arranged between the reservoir 15b1 (low pressure source) and the pilot chamber R11.

The actuator 16 is provided in the hydraulic paths 22, 24, 40a, 50a connecting the master chambers R1 and R2 and the wheel cylinder WC, and is a device for adjusting the outflow of brake fluid from the master chambers R1 and R2 to the wheel cylinder WC. Is. The actuator 16 is a device for adjusting the braking hydraulic pressure applied to each wheel cylinder WC, and is provided with first and second piping systems 40 and 50. The first piping system 40 controls the brake fluid pressure applied to the right front wheel Wfr and the left rear wheel Wrl, and the second piping system 50 controls the brake fluid pressure applied to the left front wheel Wfl and the right rear wheel Wrr. In this embodiment, the piping configuration is X piping.

The hydraulic pressure supplied from the master cylinder 12 is transmitted to each wheel cylinder WC through the first piping system 40 and the second piping system 50. The first piping system 40 is provided with an oil passage 40a that connects the oil passage 22 with the wheel cylinders WCfr and WCrl. The second piping system 50 is provided with an oil passage 50a that connects the oil passage 24 with the wheel cylinders WCfl and WCRR. The hydraulic pressure supplied from the master cylinder 12 is transmitted to the wheel cylinder WC through the oil passages 40a and 50a.

The oil passages 40a and 50a branch into two oil passages 40a1, 40a2, 50a1 and 50a2. The oil passages 40a1 and 50a1 are provided with first pressure boosting control valves 41 and 51 for controlling the boosting of the brake fluid pressure to the wheel cylinders WCfr and WCfl. The oil passages 40a2 and 50a2 are provided with second pressure increasing control valves 42 and 52 for controlling the increase of the brake fluid pressure to the wheel cylinders WCrl and WCrr.

These first and second pressure boosting control valves 41, 42, 51, 52 (corresponding to the "first solenoid valve") are two-position solenoid valves or differential pressure control valves (linear valves) that can control the communication / shutoff state. It is composed of. The first and second booster control valves 41, 42, 51, and 52 are in a communicating state when the control current to the solenoid coil provided is zero (when not energized), and the control current is applied to the solenoid coil. It is a normally open type solenoid valve that shuts off when it is flushed (when energized). The master chambers R1 and R2 and the wheel cylinder WC are connected by oil passages 22, 24, 40a and 50a (corresponding to "hydraulic passages").

The first and second booster control valves 41, 42, 51, 52 in the oil passages 40a and 50a and the wheel cylinders WC are connected to the reservoirs 43 and 53 through the oil passages 40b and 50b as decompression oil passages. ing. The oil passage 40b is provided with decompression control valves 44 and 45 composed of a two-position solenoid valve or a differential pressure control valve (linear valve) capable of controlling the communication / shutoff state. Further, the oil passage 50b is also provided with pressure reducing control valves 54 and 55 composed of a two-position solenoid valve or a differential pressure control valve (linear valve) capable of controlling the communication / shutoff state. The pressure reducing control valve 44 is arranged between the first pressure increasing control valve 41 and the reservoir 43. The pressure reducing control valve 45 is arranged between the second pressure increasing control valve 42 and the reservoir 43. The pressure reducing control valve 54 is arranged between the first pressure increasing control valve 51 and the reservoir 53. The pressure reducing control valve 55 is arranged between the second pressure increasing control valve 52 and the reservoir 53. These pressure reducing control valves 44, 45, 54, 55 (corresponding to the "second solenoid valve") are shut off when the control current to the solenoid coil provided is zero (when not energized). This is a normally closed type solenoid valve that communicates when a control current is passed through the solenoid coil (when energized).

Oil passages 40c and 50c serving as reflux oil passages are arranged between the reservoirs 43 and 53 and the oil passages 40a and 50a which are the main oil passages. The oil passages 40c and 50c are provided with pumps 46 and 56 that suck and discharge the brake fluid from the reservoirs 43 and 53 toward the master cylinder 12 side or the wheel cylinder WC side. The pump 46 discharges the brake fluid to the upstream side (master chamber R1 side) of the pressure boosting control valves 41 and 42 of the oil passage 40a. The pump 56 discharges the brake fluid to the upstream side (master chamber R2 side) of the pressure boosting control valves 51 and 52 of the oil passage 50a. The pumps 46 and 56 are driven by a motor 47. The pumps 46 and 56 suck the brake fluid from the reservoirs 43 and 53 and discharge it to the oil passages 40a and 50a to supply (return) the brake fluid to the master chambers R1 and R2. In other words, the pumps 46 and 56 make the fluid in the reservoirs 43 and 53 more on the master chambers R1 and R2 than the first and second booster control valves 41, 42, 51 and 52 of the oil passages 40a and 50a. Discharge to.

Further, a detection signal from the wheel speed sensor S provided on each wheel W of the vehicle is input to the brake ECU 17. The brake ECU 17 calculates each wheel speed, an estimated vehicle body speed, a slip ratio, and the like based on the detection signal of the wheel speed sensor S. The brake ECU 17 executes ABS control (anti-skid control) or the like based on these calculation results. A dead zone having a certain width is set for the target servo pressure (corresponding to the "target pressure") set by the brake ECU 17 according to the brake operation and the situation. The initial setting values of the dead zone (first low-voltage side threshold value and second high-voltage side threshold value described later) may be set to a constant width centered on the target servo pressure, but the target servo is based on a preset rule. It may be set for each pressure change status and the target servo pressure. In normal brake control (control that is not traction control), the brake ECU 17 sets a target servo pressure based on at least one of the stroke and the operating force (treading force) of the brake pedal 11.

Various controls using the actuator 16 are commanded by the brake ECU 17. For example, the brake ECU 17 outputs a control current for controlling various control valves 41, 42, 44, 45, 51, 52, 54, 55 of the actuator 16 and a motor 47 for driving a pump, thereby outputting the actuator 16. The hydraulic circuit of the wheel cylinder WC is controlled, and the wheel hydraulic pressure, which is the pressure of the wheel cylinder WC, is individually controlled. The brake ECU 17 can control the actuator 16 when the wheel slips during braking, and can perform ABS control to prevent wheel lock by reducing, holding, and increasing the wheel hydraulic pressure. For example, the brake ECU 17 changes the target braking force of a slipped wheel when the wheel slips. It can be said that the actuator 16 is an ABS (anti-lock braking system).

(Correction control of dead zone during traction control)
The brake ECU 17 includes a hydraulic pressure control unit 171, a slip calculation unit 172, a traction control unit 173, and a dead zone setting unit 174 as functions. The hydraulic pressure control unit 171 sets the target servo pressure, which is the target value of the servo pressure, and sets the range from the low pressure side threshold value lower than the target servo pressure to the high pressure side threshold value higher than the target servo pressure as a dead zone, and sets the servo pressure. When the actual servo pressure, which is the actual value, is a value outside the dead zone, the booster mechanism 15 is controlled so that the actual servo pressure approaches the target servo pressure, and when the actual servo pressure is a value within the dead zone, the actual servo pressure is actually measured. The booster mechanism 15 is controlled (holding control) so as to hold the servo pressure. The hydraulic pressure control unit 171 executes pressure boosting control on the boosting mechanism 15 when the actual servo pressure is less than the low pressure side threshold value, and controls the boosting mechanism 15 when the actual servo pressure is higher than the high pressure side threshold value. And execute decompression control.

More specifically, when the actual servo pressure is less than the low pressure side threshold value, the hydraulic pressure control unit 171 closes the pressure reducing valve 15b6 and opens the pressure increasing valve 15b7. When the actual servo pressure is higher than the high pressure side threshold value, the hydraulic pressure control unit 171 opens the pressure reducing valve 15b6 and closes the pressure increasing valve 15b7. When the actual servo pressure is a value within the dead zone, the hydraulic pressure control unit 171 closes the pressure reducing valve 15b6 and the pressure increasing valve 15b7.

The slip calculation unit 172 calculates a slip-related value related to the degree of slip (acceleration slip) when the vehicle is accelerating. The slip calculation unit 172 calculates a slip-related value using the detection result (wheel speed) of the wheel speed sensor S. The slip-related value is a value indicating the degree of slip of each drive wheel (in the case of front wheel drive, front wheel Wfr, Wfl), and examples thereof include a slip ratio, a slip amount, and a value corresponding thereto. The slip ratio can be defined as the ratio of the wheel speed minus the vehicle body speed to the vehicle body speed during acceleration. The slip ratio during deceleration can also be defined as the ratio of the value obtained by subtracting the wheel speed from the vehicle body speed to the vehicle body speed. Further, the slip amount can be defined as a value obtained by subtracting the vehicle body speed from the wheel speed. The slip-related value of the present embodiment is the slip ratio at the time of acceleration, and the larger the value, the more slip (idle rotation) is indicated. The brake ECU 17 can estimate (calculate) the vehicle body speed from a known method, for example, the wheel speed of a driven wheel (non-driving wheel), a detection result of an acceleration sensor (not shown), a detection result of an optical sensor, or the like. Further, since all slip-related values other than the slip ratio such as the slip amount can be converted into the slip ratio, the concept of comparing the magnitude of the slip ratio and its threshold is based on the comparison of the magnitude of other slip-related values and their thresholds. Is included.

The traction control unit 173 sets a target braking force according to the slip-related value regardless of the operation of the brake pedal based on the slip-related value calculated by the slip calculation unit 172, and sets a target servo pressure according to the target braking force. Execute traction control to set. The target braking force is set as a target value (target wheel hydraulic pressure) of the pressure of each wheel cylinder WC. The target braking force (ie, target wheel hydraulic pressure) is set based on the difference between the actual slip-related value and the preset target slip-related value. Traction control is a control that brings a slip-related value (slip ratio) closer to a target value (target slip ratio) by generating a braking force on the wheel W regardless of the driver's intention, or a predetermined slip-related value. The control is within the permissible range. As described above, the vehicle braking device A includes a traction control system. Further, the traction control of the present embodiment can be said to be acceleration slip suppression control.

The traction control unit 173 first determines whether or not the slip-related value is larger than the first threshold value. The traction control unit 173 executes traction control when the slip-related value is larger than the first threshold value (for example, the upper limit of the allowable range). Specifically, the traction control unit 173 sets the maximum value of the target braking force of each wheel W, that is, the target servo pressure corresponding to the maximum value of the hydraulic pressure of each target wheel. In this way, the traction control unit 173 increases the target servo pressure according to the slip-related value when the traction control is started. The traction control unit 173 ends the traction control when the slip-related value becomes equal to or less than the first threshold value during the traction control.

Further, when the traction control unit 173 decompresses only a part of the plurality of wheel cylinders WC according to the slip-related value of each wheel W during the traction control, the traction control unit 173 executes a specific decompression control on the wheel cylinder WC to be decompressed. To do. In the specific decompression control, for example, when only the wheel cylinder WC of the right front wheel Wfr is depressurized, the first pressure boosting control valve 41 is closed, the pressure reducing control valve 44 is opened, and the pump 46 is driven. The specific decompression control for the other wheel cylinder WC also performs the same control for the corresponding solenoid valves (pressure increase control valve and decompression control valve). When the pressure is reduced only for some wheel cylinders WC, for example, the road surface μ (coefficient of friction) is different for each wheel, so that only the slip-related value of some wheels W becomes near the target value first. For example.

At the start of traction control, the dead zone setting unit 174 sets the first low-voltage side threshold value as the low-voltage side threshold value and sets the first high-voltage side threshold value as the high-voltage side threshold value. The first low-voltage side threshold value and the first high-voltage side threshold value can be said to be initial values of the dead zone. Then, the dead zone setting unit 174 executes a control for expanding the width of the dead zone according to the control state of the traction control. Specifically, the dead zone setting unit 174 executes "first correction control" for setting the low voltage side threshold value of the dead zone to the second low voltage side threshold value lower than the first low voltage side threshold value according to the control state of the traction control. To do. The dead zone setting unit 174 of the present embodiment determines whether or not the slip-related value has changed from a state in which the slip-related value is equal to or higher than the second threshold value (corresponding to a “predetermined value”) to a state smaller than the second threshold value as a determination of the control state of the traction control. Is determined. The second threshold value is set to a value larger than the first threshold value (second threshold value> first threshold value).

The dead zone setting unit 174 makes the first correction when the slip-related value changes from a state of the second threshold value or higher to a state smaller than the second threshold value (hereinafter, also referred to as a “predetermined decrease state”) during traction control. Take control. In other words, the dead zone setting unit 174 sets the low pressure side threshold value of the dead zone to the second low voltage side threshold value lower than the first low pressure side threshold value in a state where the acceleration slip is toward convergence during traction control. Whether or not it is in a predetermined decrease state can be determined based on, for example, a plurality of slip-related values calculated at predetermined intervals.
Here, the dead zone setting unit 174 of the present embodiment does not execute the first correction control until a predetermined time elapses after the traction control is started. That is, the dead zone setting unit 174 executes the first correction control when a predetermined time has elapsed from the start time of the traction control and the slip-related value becomes a predetermined decrease state even once during the traction control. In other words, the dead zone setting unit 174 sets the first low-voltage side threshold value as the low-voltage side threshold value from the start of the traction control until the predetermined condition is satisfied, and after the predetermined condition is satisfied in the traction control, The second low-voltage side threshold value lower than the first low-voltage side threshold value is set as the low-voltage side threshold value, and this predetermined condition states that "a predetermined time has elapsed since the traction control was started and the slip-related value is once in a predetermined decrease state. It is set to "That".

In this way, the dead zone setting unit 174 does not execute the first correction control in the state before the slip tends to converge (initial stage of traction control), and the normal dead zone (initial setting dead zone) is maintained. It can be said that the dead zone setting unit 174 determines whether or not the traction control is in the initial stage based on the elapsed time and the change state of the slip-related value.
Further, the dead zone setting unit 174 executes "second correction control" for setting the high voltage side threshold value of the dead zone to a second high voltage side threshold value higher than the first high voltage side threshold value according to the control state of the traction control. .. The dead zone setting unit 174 executes the second correction control when the specific decompression control is executed during the traction control. Specifically, the dead zone setting unit 174 sets the first high-voltage side threshold value as the high-voltage side threshold value when the traction control is started, and when the pumps 46 and 56 are operated in the traction control, the first high-voltage side threshold value is used. The second high-voltage side threshold, which is also high, is set as the high-voltage side threshold. The dead zone setting unit 174 of the present embodiment sets the first high pressure side threshold value as the high pressure side threshold value when the pumps 46 and 56 are stopped, and when the pumps 46 and 56 are operating, the first high pressure side threshold value is set. 1 A second high-voltage side threshold value higher than the high-voltage side threshold value is set as the high-voltage side threshold value.

The dead zone setting unit 174 ends the correction control (first and second correction control) when the traction control ends. That is, when the traction control is completed, the dead zone setting unit 174 returns the dead zone to the initial setting value before correction. Once executed, the first correction control of the present embodiment is set to continue during the traction control. The second correction control of the present embodiment is set to end with the end of the specific decompression control.

Here, an example of correction control will be described by taking a front-wheel drive vehicle having an engine E as a drive source for the wheels W as an example. As shown in FIG. 2, when the vehicle starts, acceleration slip occurs in the front wheels Wf, and traction control is started when the slip ratio exceeds the first threshold value. The dead zone setting unit 174 turns on the initial determination when the traction control is started (that is, determines that it is "initial"), and the first is from the state where a predetermined time has elapsed from the start of the traction control and the slip ratio is equal to or higher than the second threshold value. 2 Turns off the initial judgment when the state shifts to a state smaller than the threshold value (that is, it is judged as "not initial").

The target servo pressure set by the traction control unit 173 increases as the calculated slip ratio (calculated slip ratio) increases, that is, as the difference between the calculated slip ratio and the target slip ratio (constant) increases. Become. Then, the target servo pressure becomes lower as the calculated slip ratio decreases. Then, when the acceleration slip tends to converge and the slip ratio becomes constant, the target servo pressure also becomes constant.

Here, when the initial determination is turned off (t1), the dead zone setting unit 174 executes the first correction control to lower the low voltage side threshold value of the dead zone by a predetermined pressure lower than the first low voltage side threshold value (initial value). To do. As a result, the width of the dead zone with respect to the target servo pressure becomes wider on the low voltage side than before the correction control is executed. Then, when the slip ratio temporarily rises again due to a change in the road surface μ (t2), the target braking force also rises and the target servo pressure also rises accordingly. In this case as well, the dead zone follows the change in the target servo pressure while expanding to the low voltage side.

Then, when only the calculated slip ratio of the left front wheel Wfl decreases (t3), for example, only the road surface μ of the left front wheel Wfl changes, the traction control unit 173 targets the left front wheel Wfl according to the decrease of the slip ratio. Only the braking force is reduced. That is, the traction control unit 173 executes the specific decompression control on the wheel cylinder WC of the left front wheel Wfl. At this time (t3), the dead zone setting unit 174 executes the second correction control. That is, the dead zone setting unit 174 raises the high pressure side threshold value of the dead zone by a predetermined pressure higher than the first high pressure side threshold value (initial value). The dead zone setting unit 174 ends the second correction control when the specific decompression control ends (t4).

Here, an example of the flow up to the execution of the correction control by the brake ECU 17 will be described with reference to FIG. First, the brake ECU 17 determines whether or not traction control is being executed (S101). When the traction control is executed (S101: Yes), the brake ECU 17 determines whether or not the acceleration slip is heading toward convergence, that is, whether or not the initial stage of the traction control is completed (S102). In other words, the brake ECU 17 determines whether or not the control state of the traction control satisfies a predetermined condition (S102). When the brake ECU 17 determines that the acceleration slip is heading toward convergence (S102: Yes), the brake ECU 17 executes the first correction control (S103). Then, the brake ECU 17 determines whether or not the specific decompression control is being executed (S104). When the brake ECU 17 is executing the specific decompression control (S104: Yes), the brake ECU 17 executes the second correction control (S105).

When the traction control is not executed (S101: No), or when it is determined that the acceleration slip is not heading toward convergence, that is, when the traction control is in the initial stage (S102: No), the brake ECU 17 is the third. The correction control of 1 is not executed. Further, when the specific decompression control is not executed (S104: No), the second correction control is not executed.

(effect)
According to the present embodiment, in traction control, a target servo pressure is set according to a slip-related value, and a braking force can be generated on the wheels mainly by controlling the boosting mechanism 15. With this configuration, it is not necessary to raise the master hydraulic pressure in advance when generating braking force in traction control, and it is possible to reduce the operating noise of the actuator 16. Then, during the traction control, the low-voltage side threshold value of the dead zone is set (corrected) to the second low-voltage side threshold value lower than the first low-voltage side threshold value, which is the initial value, according to the state of the vehicle, so that the target servo pressure is obtained. The width of the dead zone becomes large, and it is possible to suppress an increase in the number of operations of the pressure reducing valve 15b6 and the pressure increasing valve 15b7.

For example, when the first correction control is not executed when the target servo pressure rises at t2 in FIG. 2, the low-voltage side threshold value of the dead zone also rises following the rise of the target servo pressure, so that the actual servo pressure rises. It can be a value outside the dead zone. In this case, the hydraulic pressure control unit 171 transmits a pressure boosting signal to the boosting mechanism 15 to execute the pressure boosting control. That is, the hydraulic pressure control by the boosting mechanism 15 is switched from the holding control to the boosting control, and the boosting valve 15b7 operates. As a result, the number of times the pressure boosting valve 15b7 is operated increases.

On the other hand, according to the present embodiment, since the width of the low-voltage side of the dead zone is increased by the first correction control, the actual servo pressure is within the dead zone even if the target servo pressure temporarily rises. It is easy to fit in and the holding control is maintained. Therefore, according to the present embodiment, it is possible to suppress an increase in the number of operations of the pressure boosting valve 15b7. Further, after the acceleration slip converges during the traction control, the slip can be suppressed by using a braking force other than the hydraulic braking force by the wheel cylinder WC, such as the generation of the engine brake by the torque control of the engine E, so that the boosting force is applied. The need for responsive control by the mechanism 15 is reduced. Therefore, the influence of the first correction control on the traction control is suppressed.

As described above, according to the present embodiment, it is possible to achieve both reduction of the operating noise of the actuator 16 and improvement of the durability of the boosting mechanism 15. Further, in the present embodiment, in the first correction control, the first correction control is executed with respect to the low voltage side threshold value of the dead zone, so that the occurrence of delay in braking force due to the large width of the upper limit side of the dead zone is generated. Be prevented.

Further, during the initial period of traction control (before the elapse of a predetermined time), there is a high possibility that the acceleration slip is before the convergence, the slip ratio is large, and it is required that the acceleration slip is quickly directed to the convergence. Here, according to the present embodiment, the first correction control is not executed during the initial period of the traction control. As a result, the boosting mechanism 15 is pressure-increased and controlled by a normal reaction in response to an increase in the target servo pressure, and the acceleration slip can be quickly converged. During the initial period of traction control, control is executed in which the convergence of the acceleration slip is prioritized over the number of times the solenoid valve of the booster mechanism 15 is operated.

In addition, the dead zone setting unit 174 also determines "whether or not the acceleration slip is heading toward convergence" based on whether or not the slip-related value has changed from a state of the second threshold value or higher to a state of being smaller than the second threshold value. There is. As a result, the correction control can be executed at a more appropriate timing according to the actual slip state of the vehicle. After the slip-related value becomes less than the second threshold value, it becomes possible to respond to the subsequent increase in the slip-related value by, for example, the engine brake of the engine E, and the influence of the first correction control on the traction control is suppressed. Will be done. Examples of the braking force other than the hydraulic braking force include engine braking and regenerative braking force.

Further, in a configuration in which common master chambers R1 and R2 are provided for a plurality of wheel cylinders WC as in the present embodiment, in order to reduce the wheel hydraulic pressure of some of the wheels W, the actuator 16 is used. Specific decompression control is executed by. That is, at this time, the pumps 46 and 56 start to function. By driving the pumps 46 and 56, the brake fluid in the wheel cylinder WC to be decompressed is discharged toward the master chambers R1 and R2 of the actuator 16 via the reservoirs 43 and 53. Due to this pump back, the master hydraulic pressure rises during the specific decompression control, and the actual servo pressure also rises in conjunction with it. Due to this increase in the actual servo pressure, the actual servo pressure may become larger than the threshold value on the high voltage side of the dead zone. On the other hand, according to the present embodiment, since the width of the upper limit side of the dead zone is increased by the second correction control during the specific decompression control, it is suppressed that the actual servo pressure becomes a value outside the dead zone. To. That is, it is possible to suppress an increase in the number of operations of the pressure reducing valve 15b6.

In the present embodiment, since the booster mechanism 15 has the regulator 15a, the actual servo pressure increased by the specific decompression control is adjusted to the value before the increase with the passage of time due to the mechanical operation of the regulator 15a. It will decrease. Specifically, the spool valve 15a2 moves forward (moves to the left side in FIG. 1) due to an increase in the actual servo pressure, the port PT14 opens, and the brake fluid flows out to the reservoir 15b1. As a result, the actual servo pressure is reduced to a pressure corresponding to the pilot pressure. Therefore, the second correction control of the present embodiment is set to end when the specific decompression control ends. As a result, the expansion of unnecessary dead zones is suppressed. Further, since all the correction control ends when the traction control ends, unnecessary expansion of the dead zone is prevented.

(Other)
The present invention is not limited to the above embodiment. For example, the dead zone setting unit 174 may simply set the slip ratio to be less than a predetermined value (that is, an execution condition of the first correction control) regardless of whether or not it is in a predetermined decrease state. For example, the dead zone setting unit 174 sets the first low-voltage side threshold value as the low-voltage side threshold value when the slip ratio is equal to or higher than a predetermined value, and sets the second low-voltage side threshold value when the slip ratio is less than the predetermined value. May be set as the low pressure side threshold value. Since the increase in the slip ratio during acceleration occurs in a relatively short period of time, the period in which the slip ratio is less than a predetermined value at the initial stage of traction control is relatively short. Therefore, the first correction control executed during the period does not significantly affect the control of the braking force. Then, even in this case, since the first correction control is executed in the predetermined reduction state, the same effect as that of the above embodiment is exhibited. Further, by setting "the slip ratio is less than the predetermined value and the predetermined time has elapsed from the start of the traction control" as a predetermined condition, the state in which the slip ratio that occurs at the initial stage of the traction control is less than the predetermined value is the execution target of the correction control. Can be excluded from the state. As a result, the same effect as that of the above embodiment is exhibited.

Further, the second correction control may be set to be executed until the traction control is completed. When the booster mechanism 15 does not have the regulator 15a with respect to the servo chamber R5, the actual servo pressure once increased is maintained as long as the holding control is continued. Therefore, in the case of such a configuration, it is preferable that the second correction control is executed until the traction control is completed. Further, the second correction control may be set to end after a predetermined time from the end of the specific decompression control.

In addition, the first correction control is predetermined after the traction control is started without setting the slip-related value to be in the predetermined decrease state (or simply the slip-related value is less than the predetermined value) as a predetermined condition. It may be set to be executed after a lapse of time. Further, the predetermined time related to the passage from the start of traction control may be set based on, for example, the time (average time, etc.) required for the acceleration slip to converge, which is obtained in advance by simulation or the like. Further, in the first correction control, when the slip-related value becomes a predetermined decrease state (or the slip-related value is simply less than the predetermined value) without setting a predetermined time elapses from the start of the traction control as a predetermined condition. It may be set to be executed when (when becomes). Further, the predetermined condition may be "the slip-related value has been constantly switched from the decreasing gradient". In any case, the dead zone setting unit 174 does not execute the first correction control at the initial stage of the traction control, and executes the first correction control when the initial stage of the traction control ends.

Further, the slip ratio may be defined by wheel speed / vehicle body speed. In addition, the servo pressure corresponds to the master hydraulic pressure and also corresponds to the pilot pressure. Further, the traction control may be as follows. That is, the brake ECU 17 calculates the wheel acceleration or the vehicle body acceleration from the detection result of the wheel speed sensor S, calculates the target acceleration from the target braking force of each wheel W, and the excess or deficiency from the deviation between the target acceleration and the actual acceleration. The braking force of each wheel W may be calculated and the braking force of each wheel W may be corrected based on the calculation result. Further, the brake ECU 17 estimates the road surface μ or the road surface condition (for example, usually a snowy road or a gravel road), and sets the second threshold value and the predetermined time required for the passage from the start of traction control according to the estimation result. You may change it.

(Summary)
In the vehicle braking device A of the present embodiment, the master cylinder 12 having the master chambers R1 and R2 in which the master hydraulic pressure is generated by driving the master pistons 12c and 12d, and the driving hydraulic pressure applied to the driving of the master pistons 12c and 12d ( The drive hydraulic pressure chamber R5 that generates the drive hydraulic pressure), the valve portion 15 that adjusts the inflow and outflow of fluid to and from the drive hydraulic pressure chamber R5, and the target pressure (target servo pressure) that is the target value of the drive hydraulic pressure are set. The range from the low pressure side threshold value lower than the target pressure to the high pressure side threshold value higher than the target pressure is set as the dead zone, and when the actual pressure, which is the actual value of the driving fluid pressure, is a value outside the dead zone, the actual pressure is set to the target pressure. The hydraulic pressure control unit 171 that controls the valve unit 15 so as to bring them closer to each other and controls the valve unit 15 so as to maintain the actual pressure when the actual pressure is within the dead zone, the master chambers R1 and R2, and the wheel cylinder. An actuator 16 provided in the hydraulic passages 22, 24, 40a, 50a connecting the WC and adjusting the outflow of fluid from the master chambers R1 and R2 to the wheel cylinder WC, and an actuator 16 controlled by the actuator 16 when accelerating the vehicle. It includes a traction control unit 173 that executes traction control that suppresses slippage, and a dead zone setting unit 174 that expands the width of the dead zone according to the control state of the traction control.
Further, the dead zone setting unit 174 sets the first low pressure side threshold value as the low pressure side threshold value from the start of the traction control until the predetermined condition is satisfied, and after the predetermined condition is satisfied in the traction control, the first low pressure side threshold value is set. 1 The second low-voltage side threshold value lower than the low-voltage side threshold value is set as the low-voltage side threshold value, and the predetermined conditions are (1) a predetermined time has elapsed since the traction control was started, and (2) the slip ratio of the slip. It includes being less than a predetermined value, or (3) a predetermined time has elapsed since the traction control was started, and the slip ratio is less than the predetermined value. That is, the dead zone setting unit 174 executes the first correction control when the predetermined condition including any one of the above (1) to (3) is satisfied.
Further, the actuator 16 includes the first solenoid valves 41, 42, 51 and 52 provided in the hydraulic passages 40a and 50a, and the second solenoid valves 44 provided between the wheel cylinder WC and the reservoirs 43 and 53. Pumps 46, 56 that discharge the fluid in the reservoirs 43, 53 and the fluids in the reservoirs 43, 53 to the parts on the master chambers R1, R2 side of the first solenoid valves 41, 42, 51, 52 of the hydraulic passages 40a, 50a. When the traction control is started, the dead zone setting unit 174 sets the first high pressure side threshold value as the high pressure side threshold value, and when the pumps 46 and 56 are operated in the traction control, the first high pressure side is set. A second high-pressure side threshold value higher than the threshold value is set as the high-pressure side threshold value (that is, the second correction control is executed).

11 ... Brake pedal (brake operating member), 12 ... Master cylinder, 12c ... First master piston, 12d ... Second master piston, 15 ... Boost mechanism (valve), 16 ... Actuator, 41, 42, 51, 52 ... 1st, 2nd boost control valve (1st solenoid valve), 44, 45, 54, 55 ... Pressure reducing control valve (2nd solenoid valve), 46, 56 ... Pump, 17 ... Brake ECU, 171 ... Hydraulic pressure Control unit, 172 ... Slip calculation unit, 173 ... Traction control unit, 174 ... Dead zone setting unit, A ... Vehicle braking device, R1 ... First master room, R2 ... Second master room, R5: Servo room (driving hydraulic pressure) Room), W ... Wheels, WC ... Wheel cylinders.

Claims (2)

A master cylinder having a master chamber in which a master hydraulic pressure is generated by driving a master piston,
A drive hydraulic chamber that generates a drive hydraulic pressure for driving the master piston, and
A valve portion that adjusts the inflow and outflow of fluid to and from the drive hydraulic chamber,
The target pressure, which is the target value of the driving hydraulic pressure, is set, and the actual value of the driving hydraulic pressure is set with the range from the low pressure side threshold value lower than the target pressure to the high pressure side threshold value higher than the target pressure as a dead zone. When the actual pressure is a value outside the dead zone, the valve portion is controlled so that the actual pressure approaches the target pressure, and when the actual pressure is a value within the dead zone, the actual pressure is held. A hydraulic pressure control unit that controls the valve unit so as to
An actuator provided in a hydraulic path connecting the master chamber and the wheel cylinder to adjust the outflow of fluid from the master chamber to the wheel cylinder.
A traction control unit that executes traction control that suppresses slippage during acceleration of the vehicle by controlling the actuator, and
A dead zone setting unit that expands the width of the dead zone according to the control state of the traction control, and
Equipped with a,
The dead zone setting unit sets the first low-voltage side threshold value as the low-voltage side threshold value from the start of the traction control until the predetermined condition is satisfied, and after the predetermined condition is satisfied in the traction control, A second low-voltage side threshold value lower than the first low-voltage side threshold value is set as the low-voltage side threshold value.
The predetermined conditions are that a predetermined time has elapsed since the traction control was started, that the slip ratio of the slip is less than a predetermined value, or that a predetermined time has elapsed since the traction control was started and the slip. A braking device for a vehicle , including that the slip ratio of the vehicle is less than a predetermined value . A master cylinder having a master chamber in which a master hydraulic pressure is generated by driving a master piston,
A drive hydraulic chamber that generates a drive hydraulic pressure for driving the master piston, and
A valve portion that adjusts the inflow and outflow of fluid to and from the drive hydraulic chamber,
The target pressure, which is the target value of the driving hydraulic pressure, is set, and the actual value of the driving hydraulic pressure is set with the range from the low pressure side threshold value lower than the target pressure to the high pressure side threshold value higher than the target pressure as a dead zone. When the actual pressure is a value outside the dead zone, the valve portion is controlled so that the actual pressure approaches the target pressure, and when the actual pressure is a value within the dead zone, the actual pressure is held. A hydraulic pressure control unit that controls the valve unit so as to
An actuator provided in a hydraulic path connecting the master chamber and the wheel cylinder to adjust the outflow of fluid from the master chamber to the wheel cylinder.
A traction control unit that executes traction control that suppresses slippage during acceleration of the vehicle by controlling the actuator, and
A dead zone setting unit that expands the width of the dead zone according to the control state of the traction control, and
With
The actuator uses a first solenoid valve provided in the hydraulic path, a second solenoid valve provided between the wheel cylinder and the reservoir, and the fluid in the reservoir as the first solenoid valve of the hydraulic path. It has a pump that discharges to the part on the master chamber side of the solenoid valve.
The dead zone setting unit sets the first high pressure side threshold value as the high pressure side threshold value when the traction control is started, and is higher than the first high pressure side threshold value when the pump is operated in the traction control. setting the second high side threshold as the high-side threshold, the car dual braking system.

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