JP2008168785A - Brake control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To securely alleviate operation force for a parking brake actuation member under consideration of various states of a vehicle. <P>SOLUTION: In the brake control device 200, a wheel speed sensor 96 detects the speed of the vehicle 80, and a brake temperature estimation part estimates the temperature of a brake pad and a disc rotor by use of the detected speed of the vehicle 80. When an operation of a parking lever 93 is detected, an ECU 70 adds pressure in accordance with the estimated temperature of the brake pad and the disc rotor, to wheel cylinder pressure being fluid pressure of working fluid of a wheel cylinder 88. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a brake control technique, and more particularly to a brake control technique for reducing an operation force when operating a parking brake.

  The vehicle is provided with a parking brake for maintaining the vehicle stopped. This parking brake is generally activated by a driver operating a parking brake operating member such as a parking brake lever or a parking brake pedal. Since the driver must operate the parking brake operating member to such an extent that the vehicle can be maintained in a stopped state by his / her operating force, reduction of the operating force of the parking brake operating member is always required.

On the other hand, a so-called built-in caliper type disc brake device having both functions of a service brake and a parking brake is known. In such a disc brake device, the brake pad included in the service brake mechanism is pressed against the friction sliding surface of the disc rotor by operating the parking brake operating member. By utilizing the characteristics of such a built-in caliper disc brake device, the wheel cylinder pressure is increased when the parking brake is operated, and the brake pad is operated by both the operating force of the parking brake operating member and the wheel cylinder pressure. A technique for reducing the operating force of a brake operating member is known (see, for example, Patent Document 1 and Patent Document 2).
JP 2000-203410 A JP 2005-343194 A

  For example, when the temperature of the disc wheel and the brake pad becomes high, the friction coefficient between them becomes small. Further, for example, there are cases where many occupants of the vehicle are on board or heavy loads are loaded. In such a case, it may be necessary to operate the parking brake operating member with a large operating force in order to reliably brake the vehicle.

  The present invention has been made in view of these problems, and an object thereof is to reliably reduce the operating force of the parking brake operating member in consideration of various states of the vehicle.

  In order to solve the above problems, a brake control device according to an aspect of the present invention is configured to push a friction sliding member that rotates together with a wheel with a pressing force corresponding to a wheel cylinder pressure that is a hydraulic pressure of hydraulic fluid in the wheel cylinder. A hydraulic brake mechanism that applies a braking force to the wheel by pressing the contact member, a hydraulic brake control unit that increases the wheel cylinder pressure in accordance with the amount of operation of the brake pedal by the driver, and a pressing member. A parking brake operating member, and a parking brake operating detecting means for detecting an operation of the parking brake operating member, and a parking brake mechanism that presses the pressing member against the friction sliding member when the parking brake operating member is operated. And comprising. When the operation of the parking brake operating member is detected, the hydraulic brake control unit increases the wheel cylinder pressure to a pressure corresponding to the temperature of the friction sliding member or the pressing member.

  According to this aspect, the wheel cylinder pressure that is increased to reduce the operating force of the parking brake operating member is changed according to the difference in the frictional force between the pressing member and the frictional sliding member due to the difference in temperature. Can be made. For this reason, it is possible to appropriately reduce the operation force of the parking brake operating member while suppressing a decrease in the braking force.

  The brake control device according to an aspect of the present invention may further include vehicle speed detection means for detecting the speed of the vehicle. The hydraulic brake control unit may estimate the temperature of the frictional sliding member or the pressing member using a change in the vehicle speed detected by the vehicle speed detecting means.

  Generally, since the pressing member is provided so as to be replaceable, providing a temperature sensor or the like on the pressing member increases the cost. In addition, since the friction sliding member is rotatably provided with the wheel, it is difficult to provide a temperature sensor or the like. On the other hand, when the vehicle decelerates, the velocity energy of the vehicle is consumed as frictional heat between the pressing member and the friction sliding member. Therefore, by paying attention to the change in the speed of the vehicle, the pressing member or the friction sliding member is It is possible to estimate the temperature of the moving member. According to this aspect, it is possible to easily estimate the temperature of the frictional sliding member or the pressing member using the change in the speed of the vehicle that is easy to detect.

  Another aspect of the present invention is also a brake control device. This device is a hydraulic pressure that applies a braking force to a wheel by pressing the pressing member against a friction sliding member that rotates together with the wheel with a pressing force according to the wheel cylinder pressure that is the hydraulic pressure of the hydraulic fluid in the wheel cylinder. It has a brake mechanism, a hydraulic brake control unit that increases the wheel cylinder pressure according to the amount of operation of the brake pedal by the driver, and a parking brake operating member connected to the pressing member, and the parking brake operating member operates Thus, a parking brake mechanism that presses the pressing member against the friction sliding member, and a parking brake operation detecting means that detects the operation of the parking brake operating member are provided. The hydraulic brake control unit increases the wheel cylinder pressure to a pressure corresponding to the operating force of the brake pedal when the operation of the parking brake operating member is detected.

  For example, when stopping a vehicle on a slope with many occupants or heavy loads loaded on the vehicle, not only the slope angle of the slope but also the mass of the vehicle is the operating force of the parking brake operating member. To affect. In such a case, it is considered that the operating force of the brake pedal by the driver increases. According to this aspect, it is possible to estimate the braking force required to maintain the stop state of the vehicle when the parking brake is operated, using the operation force of the brake pedal by the driver. For this reason, even with such a configuration, it is possible to appropriately reduce the operating force of the parking brake operating member while suppressing a decrease in the braking force.

  According to the brake control device of the present invention, it is possible to reliably reduce the operating force of the parking brake operating member in consideration of various states of the vehicle.

  Hereinafter, embodiments of the present invention (hereinafter referred to as “embodiments”) will be described in detail with reference to the drawings.

  FIG. 1 is an overall configuration diagram schematically showing the configuration of a vehicle 80 equipped with a brake control device 200 according to the present embodiment. The vehicle 80 includes a vehicle main body 82, a right front wheel 84FR, a left front wheel 84FL, a right rear wheel 84RR, and a left rear wheel 84RL (hereinafter collectively referred to as “wheels 84” as necessary).

  The vehicle body 82 includes a right front wheel brake unit 86FR, a left front wheel brake unit 86FL, a right rear wheel brake unit 86RR, and a left rear wheel brake unit 86RL (hereinafter collectively referred to as “brake” as necessary. The unit 86 "is provided in the vicinity of the corresponding wheel 84. A so-called disc brake device is employed for the brake unit 86, and a friction sliding surface of a disc rotor (not shown) that rotates together with the wheel 84 corresponds to a wheel cylinder pressure that is a working hydraulic pressure in the wheel cylinder 88. A braking force is applied to the wheel 84 by pressing a brake pad (not shown) with the applied force.

  Further, a built-in caliper disc brake device is employed for the right rear wheel brake unit 86RR and the left rear wheel brake unit 86RL. The configurations of the right rear wheel brake unit 86RR and the left rear wheel brake unit 86RL will be described later with reference to FIG.

  The right front wheel brake unit 86FR, the left front wheel brake unit 86FL, the right rear wheel brake unit 86RR, and the left rear wheel brake unit 86RL are respectively a right front wheel wheel cylinder 88FR, a left front wheel wheel cylinder 88FL, and a right rear wheel. Wheel cylinder 88RR and left rear wheel wheel cylinder 88RL (hereinafter collectively referred to as "wheel cylinder 88" as necessary). The hydraulic brake mechanism 10 includes the brake unit 86 and the hydraulic actuator 60. The configuration of the hydraulic brake mechanism 10 will be described in detail with reference to FIG.

  The brake control device 200 includes a hydraulic brake mechanism 10, a parking brake switch (hereinafter referred to as “PKB switch”) 90, a parking brake / stroke sensor (hereinafter referred to as “PKB stroke sensor”) 92, a G sensor 94, and a wheel speed sensor. 96 and an electronic control unit (hereinafter referred to as “ECU”) 70.

  The PKB switch 90 is turned on when a rotation operation of a parking brake lever 93 provided in the vicinity of a driver's seat in the vehicle cabin is manually started by the driver to operate the parking brake. Instead of the parking brake lever 93, a parking brake pedal that is depressed by the driver may be provided. The PKB stroke sensor 92 detects the operation amount of the parking brake lever 93.

  One end of a wire (not shown) is connected to the parking brake lever 93, and the wire is pulled when the parking brake lever 93 is rotated. The PKB stroke sensor 92 detects the operation amount of the parking brake lever 93 by detecting the pulling amount of the wire.

  The G sensor 94 is provided in the vehicle main body 82 and detects gravity applied to a predetermined direction of the vehicle 80 such as a downward direction of the vehicle 80 when the vehicle 80 is in a horizontal state. One wheel speed sensor 96 is provided corresponding to each of the four wheels 84, and detects the rotational speed of the wheels 84. The wheel speed sensor 96 has a pickup coil, detects a pulser that rotates with the wheel 84, and detects the rotation of the wheel 84. The PKB switch 90, the PKB stroke sensor 92, the G sensor 94, and the wheel speed sensor 96 are connected to the ECU 70, and each detection result is output to the ECU 70.

  FIG. 2 is a cross-sectional view showing in detail the configuration of a right rear wheel brake unit 86RR as an example of the built-in caliper brake unit 86 according to this embodiment. In FIG. 2, the left direction is the vehicle outer direction, and the right direction is the vehicle inner direction.

  The right rear wheel brake unit 86RR includes a caliper unit 110, a brake pad 132, and a disc rotor 134. The caliper unit 110 includes a caliper body 120, a piston 126, a right rear wheel wheel cylinder 88RR, and a parking brake mechanism 140. The configuration of the left rear wheel brake unit 86RL is the same as that of the right rear wheel brake unit 86RR except that a left rear wheel wheel cylinder 88RL having the same shape as that of the right rear wheel wheel cylinder 88RR is provided instead of the right rear wheel wheel cylinder 88RR. It is the same.

  The disk rotor 134 is formed in a disk shape. Friction sliding surfaces 134 a are provided on both side surfaces of the disk rotor 134 in a range of a predetermined length from the vicinity of the outer periphery of the disk rotor 134 to the radially inward direction.

  The caliper body 120 has a cylinder housing 120a and a claw portion 120b. The cylinder housing 120a and the claw portion 120b are opposed to each other, and are partially coupled together. As a result, the caliper body 120 is formed in a U shape.

  The piston 126 is formed in a cup shape having an outer diameter substantially the same as the inner diameter of the cylinder portion 120c. The right rear wheel wheel cylinder 88RR is formed in a cup shape having an outer diameter substantially the same as the inner diameter of the piston 126. The right rear wheel wheel cylinder 88RR is inserted into the piston 126 so that the opening side is in the same direction.

  Inside the cylinder housing 120a, a cylinder portion 120c, which is a cylindrical space portion that opens toward the claw portion 120b, is provided. The piston 126 into which the right rear wheel wheel cylinder 88RR is inserted is fitted into the cylinder portion 120c so that the outer bottom surface thereof faces the claw portion 120b. Thus, a cylinder chamber in which the working fluid is accommodated is formed by the inner bottom surface of the cylinder portion 120c and the inner periphery of the right rear wheel wheel cylinder 88RR.

  The caliper body 120 according to the present embodiment is a floating type. The caliper body 120 is supported by a mounting (not shown) by a known slide pin mechanism or the like so as to be movable within a predetermined range in the left-right direction of the vehicle. At this time, the caliper body 120 is supported by the mounting so that the cylinder housing 120a is located in the vehicle interior direction, the claw portion 120b is located in the vehicle outer direction, and the central axis of the cylinder portion 120c is directed in the vehicle left-right direction. The caliper body 120 is disposed such that the friction sliding surface 134a of the disk rotor 134 is positioned between the claw portion 120b and the cylinder portion 120c.

  One brake pad 132 is disposed between the friction sliding surface 134a on the vehicle interior side and the piston 126, and between the friction sliding surface 134a on the vehicle exterior side and the claw portion 120b. The brake pad 132 is restricted from moving in the radial direction and the circumferential direction of the disk rotor 134 by mounting. However, each of the brake pads 132 is supported by the mounting so as to be movable in the axial direction of the disk rotor 134, and is positioned away from the friction sliding surface 134a of the disk rotor 134 before the piston 126 is propelled. Arranged at the initial position.

  When the wheel cylinder pressure, which is the hydraulic fluid pressure in the right rear wheel wheel cylinder 88RR, increases, the piston 126 propels toward the brake pad 132 on the vehicle inner side, and the brake pad 132 on the vehicle inner side is first moved by the piston 126. It is pushed and brought into contact with the friction sliding surface 134a inside the vehicle. Then, the entire caliper body 120 slides in the vehicle interior direction by the reaction force, and the brake pad 132 on the vehicle exterior side is pushed by the claw portion 120b and is brought into contact with the friction slide surface 134a on the vehicle exterior side. Thus, a braking force is applied to the wheel 84 by the frictional force between the brake pad 132 and the frictional sliding surface 134a of the disk rotor 134.

  When the wheel cylinder pressure in the right rear wheel wheel cylinder 88RR is reduced, the piston 126 is propelled toward the direction away from the claw 120b. As a result, each of the brake pads 132 is returned to the initial position, and the braking force applied to the wheels is released by separating from the friction sliding surface 134a of the disk rotor 134.

  The parking brake mechanism 140 includes a spindle 122, a sleeve 124, a return spring 125, a connecting link 128, and a spindle lever 130. The right rear wheel wheel cylinder 88RR is provided with an insertion hole that opens in the axial direction on the piston 126 side, and a cylindrical sleeve 124 is inserted into the insertion hole so as to be slidable in the axial direction. The sleeve 124 is disposed so as to contact the inner bottom surface of the piston 126. The spindle 122 is inserted into the through hole of the sleeve 124 and is fixed to the sleeve 124. The sleeve 124 is formed with a locking portion projecting radially outward, and a return spring 125 is disposed between the locking portion and the inner bottom surface of the piston 126. The return spring 125 biases the spindle 122 and the right rear wheel wheel cylinder 88RR against the piston 126 in a direction away from the inner bottom surface of the piston 126.

  One end of a connecting link 128 is in contact with the other end of the spindle 122. The spindle lever 130 is formed in a cylindrical shape, and a concave portion is provided on the outer peripheral portion thereof. The spindle lever 130 is inserted through the hole of the caliper body 120 so that the axial direction thereof is perpendicular to the axial direction of the piston 126. The other end of the connecting link 128 is in contact with the recess of the spindle lever 130.

  The other end of the wire whose one end is coupled to the parking brake lever 93 is joined to the spindle lever 130. When the parking brake lever 93 is turned to operate the parking brake and the wire is pulled, the spindle lever 130 is turned. When the spindle lever 130 rotates, the connecting link 128 slides from the concave portion of the spindle lever 130 toward the outer peripheral surface, thereby pushing the connecting link 128 and the spindle 122 toward the opening side of the cylinder portion 120c. As a result, the piston 126 is pushed out through the sleeve 124 and the return spring 125 in a direction protruding from the opening of the cylinder portion 120c, and the brake pad 132 is caused to frictionally slide on the disc rotor 134 in the same manner as when the wheel cylinder pressure is increased. A braking force is applied to the wheel 84 by pressing against the moving surface 134a.

  When the parking brake lever 93 is turned in the reverse direction to release the operation of the parking brake, the pulled wire is loosened and the spindle lever 130 is rotated in the reverse direction to the original initial position. As a result, the piston 126 is retracted into the cylinder portion 120c, and the brake pad 132 is separated from the friction sliding surface 134a of the disk rotor 134, and the braking force applied to the wheel 84 is reduced in the same manner as when the wheel cylinder pressure is reduced. Canceled.

  FIG. 3 is a system diagram of the hydraulic brake mechanism 10 according to the present embodiment. The hydraulic brake mechanism 10 employs an electronically controlled brake system (ECB), and independently and optimally sets the four-wheel brakes of the vehicle according to the operation of the brake pedal 12 as a brake operation member by the driver. .

  The brake pedal 12 is connected to a master cylinder 14 that sends out brake oil as hydraulic fluid in response to a depression operation by the driver. The brake pedal 12 is provided with a stroke sensor 46 that detects the depression stroke. Further, a reservoir tank 26 is connected to the master cylinder 14, and a reaction force corresponding to the operating force of the brake pedal 12 by the driver is created at one output port of the master cylinder 14 via the electromagnetic valve 23. A stroke simulator 24 is connected. The solenoid valve 23 is a so-called normally-closed linear valve, which is closed when no current is supplied, and is supplied with current when the driver depresses the brake pedal 12 and is opened.

  A brake hydraulic pressure control pipe 16 for the right front wheel 84FR is connected to one output port of the master cylinder 14. The brake hydraulic pressure control pipe 16 is connected to a right front wheel wheel cylinder 88FR that applies a braking force to the right front wheel 84FR. In addition, a brake hydraulic pressure control pipe 18 for the left front wheel 84FL is connected to the other output port of the master cylinder 14. The brake hydraulic control pipe 18 is connected to a left front wheel wheel cylinder 88FL that applies a braking force to the left front wheel 84FL.

  A right master valve 22FR is provided in the middle of the brake hydraulic pressure control pipe 16, and a left master valve 22FL is provided in the middle of the brake hydraulic pressure control pipe 18. Each of the right master valve 22FR and the left master valve 22FL is a so-called normally-open linear valve, which is closed in a state where electric current is supplied, and closes the master cylinder 14 and the right front wheel wheel cylinder 88FR or the left front wheel wheel. The communication with the cylinder 88FL is prevented, and the valve is opened by reducing or stopping the supply of current, so that the master cylinder 14 communicates with the right front wheel wheel cylinder 88FR or the left front wheel wheel cylinder 88FL.

  A right master pressure sensor 48FR that detects a master cylinder pressure on the right front wheel 84FR side is provided in the middle of the brake hydraulic pressure control pipe 16. A left master pressure sensor 48FL that detects the master cylinder pressure on the left front wheel 84FL side is provided in the middle of the brake hydraulic pressure control pipe 18 for the left front wheel. In the hydraulic brake mechanism 10, when the brake pedal 12 is depressed by the driver, the depression operation amount is detected by the stroke sensor 46, but the master cylinder detected by the right master pressure sensor 48FR and the left master pressure sensor 48FL. The depressing operation force (depressing force) of the brake pedal 12 can also be obtained from the pressure. The ECU 70 monitors the master cylinder pressure from the detection results of the right master pressure sensor 48FR and the left master pressure sensor 48FL from the viewpoint of fail-safe in consideration of the failure of the stroke sensor 46 and the like.

  One end of a hydraulic supply / discharge pipe 28 is connected to the reservoir tank 26. A suction port of a pump 34 driven by a motor 32 is connected to the other end of the hydraulic supply / discharge pipe 28. The discharge port of the pump 34 is connected to a high pressure pipe 30, and an accumulator 50 and a relief valve 53 are connected to the high pressure pipe 30. In the present embodiment, a reciprocating pump including two or more pistons (not shown) that are reciprocally moved by the motor 32 is employed as the pump 34. Further, as the accumulator 50, an accumulator that converts the pressure energy of the brake oil into the pressure energy of an enclosed gas such as nitrogen is stored.

  The accumulator 50 stores brake oil whose pressure has been increased to, for example, about 14 to 22 MPa by the pump 34. Further, the valve outlet of the relief valve 53 is connected to the hydraulic supply / discharge pipe 28. When the pressure of the brake oil in the accumulator 50 increases abnormally to about 25 MPa, for example, the relief valve 53 is opened and the high-pressure brake is opened. The oil is returned to the hydraulic supply / discharge pipe 28. Further, the high-pressure pipe 30 is provided with an accumulator pressure sensor 51 that detects the outlet pressure of the accumulator 50, that is, the pressure of the brake oil in the accumulator 50.

  The high pressure pipe 30 includes a right front wheel pressure increasing valve 40FR, a left front wheel pressure increasing valve 40FL, a right rear wheel pressure increasing valve 40RR, and a left rear wheel pressure increasing valve 40RL (hereinafter collectively referred to as “pressure increasing valve” as necessary. 40 ”), the right front wheel wheel cylinder 88FR, the left front wheel wheel cylinder 88FL, the right rear wheel wheel cylinder 88RR, and the left rear wheel wheel cylinder 88RL (hereinafter collectively referred to as necessary). (Referred to as “wheel cylinder 88”). Each of the pressure increasing valves 40 is a so-called normally closed linear valve (solenoid valve), which is closed when no current is supplied to open the wheel cylinder pressure without increasing the wheel cylinder pressure. Then, increase the wheel cylinder pressure.

  The right front wheel pressure reducing valve 42FR, the left front wheel pressure reducing valve 42FL, the right rear wheel pressure reducing valve 42RR, and the left rear wheel pressure reducing valve 42RL (hereinafter collectively referred to as “pressure reducing valve 42” as necessary) These are connected to the corresponding wheel cylinders 88. The right front wheel pressure reducing valve 42FR and the left front wheel pressure reducing valve 42FL are so-called normally-closed linear valves (solenoid valves). When the current is not supplied, the valve is closed and the wheel cylinder pressure is not reduced. When supplied, the valve opens to reduce the wheel cylinder pressure. On the other hand, the left rear wheel pressure reducing valve 42RL and the right rear wheel pressure reducing valve 42RR are so-called normally open linear valves (solenoid valves), which are closed when the current is supplied to reduce the wheel cylinder pressure. First, when the current supply is decreased or stopped, the valve is opened to reduce the wheel cylinder pressure.

  The right front wheel wheel cylinder 88FR, the left front wheel wheel cylinder 88FL, the right rear wheel wheel cylinder 88RR, and the hydraulic piping near the left rear wheel wheel cylinder 88RL respectively detect the hydraulic pressure of the corresponding wheel cylinder 88. Front wheel wheel cylinder pressure sensor 44FR, left front wheel wheel cylinder pressure sensor 44FL, right rear wheel wheel cylinder pressure sensor 44RR, and left rear wheel wheel cylinder pressure sensor 44RL (hereinafter collectively referred to as “ A wheel cylinder pressure sensor 44 ") is provided.

  The above-described master valve 22, pressure increasing valve 40, pressure reducing valve 42, pump 34, accumulator 50, master pressure sensor 48, wheel cylinder pressure sensor 44, accumulator pressure sensor 51, and the like constitute a hydraulic actuator 60. The operation of the hydraulic actuator 60 is controlled by the ECU 70.

  FIG. 4 is a functional block diagram of the brake control device 200 according to the present embodiment. In FIG. 4, the ECU 70 depicts functional blocks realized by cooperation of hardware such as CPU, ROM, or RAM and software. Therefore, these functional blocks can be realized in various forms by a combination of hardware and software.

  The ECU 70 determines the target wheel cylinder pressure to be applied to each wheel cylinder 88 using the detection results of the stroke sensor 46 and the wheel speed sensor 96. The ECU 70 determines the duty of the drive current supplied to the pressure increasing valve 40 or the pressure reducing valve 42 corresponding to the wheel cylinder 88 to be controlled so that the wheel cylinder pressure becomes the target wheel cylinder pressure. The ECU 70 supplies a control current corresponding to the determined duty to the drive circuit. The drive circuit supplies a drive current from a battery (not shown) to the pressure increasing valve 40 or the pressure reducing valve 42 to be actuated with a duty corresponding to the supplied control current. The pressure increasing valve 40 or the pressure reducing valve 42 that has received the current is opened according to the duty of the supplied driving current, and increases or decreases the wheel cylinder pressure. In this way, the ECU 70 gives each wheel 84 an optimum braking force according to the amount of depression of the brake pedal 12 or the speed of the vehicle 80. Therefore, the ECU 70 functions as a brake control unit that applies an appropriate braking force to each of the wheels 84.

  Since the frictional force between the brake pad 132 and the disc rotor 134 changes according to their temperatures, the braking force required to maintain the vehicle 80 in a stopped state is the temperature of the brake pad 132 and the disc rotor 134. It changes according to. In addition, the braking force required to maintain the stop state of the vehicle 80 also varies depending on the inclination angle of the vehicle 80 when the vehicle 80 is stopped on a slope. In addition, the braking force required to maintain the stopped state of the vehicle 80 changes according to the mass of the vehicle 80 including passengers and cargo when the vehicle 80 is stopped on a slope, for example.

  Therefore, if the wheel cylinder pressure is increased to reduce the operating force of the parking brake lever 93 without considering the values of these conditions, the parking brake lever 93 may not be sufficiently reduced. obtain. Therefore, the ECU 70 includes a brake temperature estimation unit 72, a vehicle tilt angle calculation unit 74, and a required braking force estimation unit 76.

  The brake temperature estimation unit 72 estimates the temperatures of the brake pad 132 and the disk rotor 134. For example, when the driver depresses the brake pedal 12 to stop the vehicle 80 from a certain speed, much of the speed energy of the vehicle 80 is between the brake pad 132 and the frictional sliding surface 134 a of the disc rotor 134. Consumed as frictional heat. Therefore, it is possible to estimate the temperature of the brake pad 132 and the disk rotor 134 from the change in the speed of the vehicle 80.

  For this reason, the brake temperature estimation unit 72 uses the detection result of the wheel speed sensor 96 every predetermined time from when an ignition switch (not shown) is turned on to when it is turned off, to determine the speed of the vehicle 80. The calculated speed data of the vehicle 80 is stored and accumulated in the RAM. The brake temperature estimation unit 72 estimates the current temperatures of the brake pad 132 and the disc rotor 134 from the speed data of the vehicle 80 accumulated every predetermined time. The brake pad 132 may be directly provided with a temperature sensor such as a thermocouple, and the ECU 70 may calculate the temperature of the brake pad 132 using the detected value of the temperature sensor.

  For example, when the vehicle 80 is inclined because the vehicle 80 stops on a slope, the detection value of the G sensor 94 also changes. Therefore, the vehicle tilt angle calculation unit 74 calculates the tilt angle of the vehicle 80 using the detection result of the G sensor 94. The ROM of the ECU 70 stores a correspondence relationship between the detected value of the G sensor 94 and the inclination angle of the vehicle 80 in advance, and the vehicle inclination angle calculation unit 74 calculates the inclination angle of the vehicle 80 with reference to this. As described above, the G sensor 94 also functions as a tilt angle detection unit of the vehicle 80.

  For example, when the vehicle 80 is stopped on a slope, not only the inclination angle of the vehicle 80 but also the mass of the vehicle 80 including passengers and luggage affects the turning operation force of the parking brake lever 93. When the vehicle 80 is stopped on a slope with heavy loads or passengers, the driver operates the brake pedal 12 with a strong stepping force. Thus, the braking force required to maintain the stop state of the vehicle 80 can be estimated from the depression operation force of the brake pedal 12 when the parking brake lever 93 is rotated. The detection result of the master pressure sensor 48 changes according to the operating force of the brake pedal 12 by the driver. For this reason, the required braking force estimation unit 76 uses the detection result of the master pressure sensor 48 to estimate the depressing operation force of the brake pedal 12 by the driver, and is required for maintaining the vehicle 80 in the stopped state. Estimate the braking force.

  Note that the detection result of the stroke sensor 46 and the detection result of the wheel cylinder pressure sensor 44 also change according to the operating force of the brake pedal 12 by the driver. For this reason, the required braking force estimation unit 76 estimates the depressing operation force of the brake pedal 12 by the driver using the detection result of the stroke sensor 46 or the wheel cylinder pressure sensor 44, and maintains the vehicle 80 in the stopped state. The required braking force required may be estimated.

  The ECU 70 uses the estimated temperature of the brake pad 132 and the disk rotor 134, the required braking force, and the calculated inclination angle of the vehicle 80 to increase the wheel cylinder so as to reduce the turning operation force of the parking brake lever 93. The pressure is determined, and the operation of the pressure increasing valve 40 or the pressure reducing valve 42 is controlled so as to be the determined wheel cylinder pressure. Hereinafter, the operation force reduction control of the parking brake lever 93 will be described in detail with reference to FIG.

  FIG. 5 is a flowchart illustrating a processing procedure of the operation force reduction control of the parking brake lever 93 in the brake control device 200 according to the present embodiment. The processing in this flowchart starts when the ignition switch is turned on, and is then repeatedly performed every predetermined time until the ignition switch is turned off.

  The ECU 70 determines whether the speed of the vehicle 80 is zero using the detection result of the wheel speed sensor 96 (S10). Since the operation force reduction control of the parking brake lever 93 affects the braking force applied to the wheels 84 and is not preferably performed during traveling, it is determined that the vehicle speed is not zero, that is, the vehicle 80 is traveling. If this occurs (N in S10), the processing in this flowchart ends.

When it is determined that the vehicle speed is zero, that is, the vehicle 80 is stopped (Y in S10), the ECU 70 uses the detection result of the stroke sensor 46 to determine whether or not the driver depresses the brake pedal 12. Determine (S12). If the brake pedal 12 is not depressed, it is difficult for the required braking force estimation unit 76 to estimate the required braking force, and it is difficult to determine an appropriate value for the PKB operating pressure P _PKB described later. For this reason, when the brake pedal 12 is not depressed (N in S12), the processing in this flowchart ends.

  When the brake pedal 12 is depressed (Y in S12), the ECU 70 determines whether or not the PKB switch 90 is on, so that the parking brake lever 93 is rotated to operate the parking brake. It is determined whether it has been done (S14). If the PKB switch 90 is not turned on (N in S14), the parking brake lever 93 is not operated, and it is not necessary to reduce the operating force of the parking brake lever 93, so the processing in this flowchart is terminated.

  When the PKB switch 90 is turned on (Y in S14), since the parking brake lever 93 is considered to be turned to operate the parking brake, the ECU 70 displays the detection result of the PKB stroke sensor 92. Utilizing this, it is determined whether or not the operation amount of the parking brake lever 93 is equal to or less than a threshold operation amount Lth that can be considered that the rotation operation of the parking brake lever 93 has been completed (S16). If the operation amount of the parking brake lever 93 is larger than the threshold operation amount Lth (N in S16), the rotation operation of the parking brake lever 93 is considered to be completed, and the processing in this flowchart is ended.

When it is determined that the operation amount of the parking brake lever 93 is equal to or less than the threshold operation amount Lth (Y in S16), the ECU 70 is a hydraulic brake mechanism in order to reduce the operation force of the rotation operation of the parking brake lever 93 by the driver. 10 determines whether or not the PKB operating pressure P _PKB, which is the wheel cylinder pressure for pressing the piston 126, has been determined (S18). At this time, the ECU 70 determines whether or not the PKB operation pressure P _PKB has been determined by determining whether or not the PKB operation pressure P _PKB is stored in the RAM.

When the PKB operating pressure P _PKB has not yet been determined (N in S18), the brake temperature estimation unit 72 estimates the brake pad and brake pad temperature (S20), and the vehicle inclination angle calculation unit 74 calculates the vehicle inclination. The angle is calculated (S22), and the required braking force estimation unit 76 estimates the required braking force (S24).

Next, the ECU 70 determines the PKB operating pressure P _PKB by using the estimated brake pad and brake pad temperature, the calculated vehicle inclination angle, and the estimated required braking force values (S26). ). Specifically, when the estimated temperature of the brake pad and the brake pad is high and the values of other conditions are the same, ECU 70 determines a higher PKB operating pressure P _PKB than when the temperature is low. . Further, when the calculated vehicle inclination angle is large and the values of other conditions are the same, the ECU 70 determines a higher PKB operation pressure P _PKB than when the vehicle inclination angle is small. Further, when the estimated required braking force is high and the values of other conditions are the same, the ECU 70 determines a higher PKB operating pressure P _PKB than when the required braking force is low.

The ECU 70 may determine the PKB operation pressure P _PKB by comparing the value of each condition using a threshold value, and may substitute an appropriate PKB operation pressure P by substituting the value of each condition. _The pressure P _PKB at the time of PKB operation may be determined using an arithmetic expression for obtaining _PKB . The ECU 70 stores the determined PKB operating pressure P _PKB in the RAM. The threshold value or arithmetic expression for each condition used for determining the PKB operating pressure P _PKB is stored in advance in the ROM of the ECU 70.

When the pressure P _PKB during operation P _PKB has been determined (Y in S18) or newly determined (S26), the ECU 70 determines whether the right rear wheel wheel cylinder pressure sensor 44RR and the left rear wheel wheel cylinder pressure sensor 44RL Using the detection result, it is determined whether or not the wheel cylinder pressure P _{W / S of} the right rear wheel wheel cylinder 88RR and the left rear wheel wheel cylinder 88RL is equal to or higher than the determined PKB operating pressure P _PKB (S28).

When the wheel cylinder pressure P _{W / S} is less than the PKB operating pressure P _PKB (N in S28), the ECU 70 opens the right rear wheel pressure-increasing valve 40RR and the left rear wheel pressure-increasing valve 40RL. The wheel cylinder pressure P _{W / S} of the wheel cylinder 88RR and the left rear wheel wheel cylinder 88RL is increased (S32). The ECU 70 increases the wheel cylinder pressure P _{W / S} until the wheel cylinder pressure P _{W / S} of the wheel cylinder 88RR for the right rear wheel and the wheel cylinder 88RL for the left rear wheel reaches the pressure P _PKB during PKB operation. When these wheel cylinder pressures P _{W / S} reach the PKB operating pressure P _PKB (Y in S28), the right rear wheel pressure-increasing valve 40RR and the left rear wheel pressure-increasing valve 40RL are closed and these wheels are closed. The cylinder pressure P _{W / S} is maintained (S30).

In order to reduce the turning operation force of the parking brake lever 93, the wheel cylinder pressure P _{W / S} of the right rear wheel wheel cylinder 88RR and the left rear wheel wheel cylinder 88RL is being increased or maintained. Even in this case, when the depression of the brake pedal 12 by the driver is released, the ECU 70 cancels the operation force reduction control of the parking brake lever 93 shown in FIG. 5, and the right rear wheel pressure reducing valve 42RR. Of course, the wheel cylinder pressure P _{W / S} is reduced by opening the left rear wheel pressure reducing valve 42RL.

Thus, when the parking brake lever 93 is turned by the driver, the wheel cylinder pressure P _{W / S} of the right rear wheel wheel cylinder 88RR and the left rear wheel wheel cylinder 88RL is increased, The force that pushes the piston 126 in the direction opposite to the biasing direction of the return spring 125 can be assisted by the hydraulic pressure. Specifically, when the piston 126 is pushed toward the brake pad 132 by the wheel cylinder pressure P _{W / S} , the piston 126 advances in a direction in which the return spring 125 in the piston 126 extends. For this reason, the force required for contracting the return spring 125 can be reduced, and the operating force for rotating the parking brake lever 93 can be reduced. Therefore, the ECU 70 also functions as an operation force reduction control unit for the parking brake lever 93.

In the present embodiment, the wheel cylinder pressure P _{W / S applied} to the right rear wheel wheel cylinder 88RR and the left rear wheel wheel cylinder 88RL at this time is determined based on the temperature of the brake pad 132 and the disk rotor 134, the inclination angle of the vehicle 80, Further, it can be determined in consideration of the required braking force estimated to be requested by the driver. For this reason, even if the values of these conditions change, it is possible to determine an appropriate wheel cylinder pressure P _{W / S} corresponding to these values.

  The present invention is not limited to the above-described embodiments, and various modifications such as design changes can be added to the embodiments based on the knowledge of those skilled in the art. Embodiments described may also fall within the scope of the present invention. Here are some examples.

  In a modification, an electric parking brake mechanism is provided instead of the parking brake lever 93 that is rotated by the driver. The electric parking mechanism has a parking brake switch and an actuator such as a motor. The parking brake switch is provided on an instrument panel or the like in the vehicle cabin. The actuator is actuated when the switch is turned on, and pulls the other end of the wire having one end coupled to the parking brake mechanism 140 until the wire has a predetermined tension. Since the electric parking mechanism is a known technique, further explanation is omitted.

  As described above, also in the electric parking mechanism, the burden on the actuator can be reduced by assisting the force for pushing the piston 126 when the parking brake is operated. For this reason, failure of the actuator can be suppressed, and it is possible to reduce the cost of the actuator by adopting an actuator with a small output.

1 is an overall configuration diagram schematically showing a configuration of a vehicle on which a brake control device according to an embodiment is mounted. It is sectional drawing which shows in detail the structure of the brake unit for right rear wheels as an example of the brake unit of the built-in caliper system which concerns on this embodiment. It is a systematic diagram of the hydraulic brake mechanism concerning this embodiment. It is a functional block diagram of a brake control device concerning this embodiment. It is a flowchart which shows the process sequence of the operation force reduction control of the parking brake lever in the brake control apparatus which concerns on this embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Hydraulic brake mechanism, 12 Brake pedal, 40 Pressure increase valve, 42 Pressure reduction valve, 44 Wheel cylinder pressure sensor, 48 Master pressure sensor, 60 Hydraulic actuator, 70 ECU, 72 Brake temperature estimation part, 74 Vehicle inclination angle calculation part, 76 Required braking force estimation unit, 86 Brake unit, 88 Wheel cylinder, 90 PKB switch, 92 PKB stroke sensor, 93 Parking brake lever, 94 G sensor, 96 Wheel speed sensor, 120 Caliper body, 122 Spindle, 124 Sleeve, 125 Return Spring, 126 Piston, 128 Connecting link, 130 Spindle lever, 132 Brake pad, 134 Disc rotor, 140 Parking brake Structure, 200 brake control unit.

Claims (3)

A hydraulic brake mechanism that applies a braking force to the wheel by pressing the pressing member against a friction sliding member that rotates together with the wheel with a pressing force according to the wheel cylinder pressure that is the hydraulic pressure of the hydraulic fluid in the wheel cylinder;
A hydraulic brake control unit for increasing the wheel cylinder pressure according to the amount of operation of the brake pedal by the driver;
A parking brake operating member connected to the pressing member, and a parking brake mechanism that presses the pressing member against the friction sliding member by operating the parking brake operating member;
Parking brake operation detecting means for detecting the operation of the parking brake operating member;
With
The hydraulic brake control unit increases the wheel cylinder pressure to a pressure corresponding to the temperature of the friction sliding member or the pressing member when the operation of the parking brake operating member is detected. Brake control device. Vehicle speed detecting means for detecting the speed of the vehicle,
The said hydraulic brake control part estimates the temperature of the said friction sliding member or a pressing member using the change of the speed of the vehicle detected by the said vehicle speed detection means. Brake control device. A hydraulic brake mechanism that applies a braking force to the wheel by pressing the pressing member against a friction sliding member that rotates together with the wheel with a pressing force according to the wheel cylinder pressure that is the hydraulic pressure of the hydraulic fluid in the wheel cylinder;
A hydraulic brake control unit for increasing the wheel cylinder pressure according to the amount of operation of the brake pedal by the driver;
A parking brake operating member connected to the pressing member, and a parking brake mechanism that presses the pressing member against the friction sliding member by operating the parking brake operating member;
Parking brake operation detecting means for detecting the operation of the parking brake operating member;
With
The fluid pressure brake control unit increases the wheel cylinder pressure to a pressure corresponding to an operating force of the brake pedal when the operation of the parking brake operation member is detected.

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