Vehicle braking system

Abstract

This suppresses the generation of drag torque when starting after releasing the brakes, and also prevents the piston from retracting too far. [Solution] The control unit of the brake device includes a starting detection unit that detects when the vehicle starts moving after stopping based on the vehicle speed detected by the vehicle speed detection unit, a pressure reduction processing unit that operates the brake fluid pressure circuit to reduce the brake pressure in the fluid chamber when the starting detection unit detects when the vehicle starts moving, and a pressure increase processing unit that operates the brake pressure circuit to increase the brake pressure in the fluid chamber when the brake pressure detected by the first brake pressure detection unit falls below a preset first threshold pressure.

Description

Technical Field

[0001] The present invention relates to a braking device for a vehicle.

Background Art

[0002] As a braking device for vehicles such as automobiles and motorcycles, a hydraulic disk brake device (hereinafter referred to as "disk brake device") is known. This type of disk brake device has a disk rotor that rotates with the wheel, and generates braking force by squeezing both surfaces of the disk rotor with a pair of opposing brake pads.

[0003] The braking force is obtained by hydraulically operating a caliper piston slidably inserted into a cylinder of a brake caliper (caliper cylinder), and pressing a brake pad connected to the piston against the disk rotor. A seal groove is formed on the inner circumference of the caliper cylinder.

[0004] A piston seal is fitted in this seal groove. The outer circumference of the caliper piston is in sliding contact with the inner circumference of this piston seal. This piston seal prevents leakage of the brake fluid that operates the caliper piston.

[0005] When the brake pressure is increased, the caliper piston slides and presses the brake pad against the disk rotor. At that time, the piston seal elastically deforms following the movement of the caliper piston. Also, when the brake pressure is reduced, the caliper piston is pulled back by the restoring force of the elastically deformed piston seal. When the caliper piston is pulled back, the brake pad is separated from the disk rotor and the brake is released.

[0006] By the way, the movement amount of the caliper piston during brake operation increases as the brake pressure increases. Naturally, when the movement amount of the caliper piston during brake operation is large, the return amount during brake release also becomes large.

[0007] The rigidity of the brake caliper and brake pads, as well as the deterioration of the piston seal, can increase the resistance when retracting the caliper piston. In such cases, if the amount of return of the caliper piston is large, the restoring force of the piston seal may not be sufficient to return the caliper piston to its original position.

[0008] If the caliper piston does not return to its original position, the brake pads will slide against the disc rotor during acceleration, generating drag torque. This drag torque not only worsens energy consumption (fuel efficiency, electric efficiency) but also accelerates wear on the brake pads and disc rotors, reducing their durability. Furthermore, drag torque can sometimes cause squeaking noises on the sliding surface of the disc brake.

[0009] As a countermeasure, for example, Patent Document 1 (Japanese Patent Application Publication No. 2023-144890) discloses a technology in which, when the brake pressure detected by a hydraulic pressure sensor exceeds a predetermined threshold during brake operation, an electric actuator is operated in a direction that causes the caliper piston to retract from the disc rotor when the brake is subsequently released. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Publication No. 2023-144890 [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] However, the technology disclosed in Patent Document 1 uses an electric actuator to forcibly retract the caliper piston. However, if the caliper piston is retracted uniformly by an electric actuator, over-retraction may occur.

[0012] If the caliper piston is retracted too far, a delay occurs before the brakes actually engage during subsequent braking operations. This delay causes a delay in brake activation.

[0013] The present invention aims to provide a vehicle braking system that can quickly suppress the generation of drag torque when starting after releasing the brakes, and can also prevent the piston from retracting too far, thereby preventing a delay in brake operation during the next brake operation. [Means for solving the problem]

[0014] The present invention provides a disc brake comprising: a vehicle speed detection unit for detecting the vehicle speed; a piston for pressing brake pads against a disc rotor; a cylinder through which the piston is inserted; and a piston seal fitted into a seal groove formed in the cylinder, with its inner circumference sliding against the piston, wherein a hydraulic chamber is defined by the piston, the cylinder, and the piston seal; a brake fluid pressure circuit for supplying and discharging brake fluid to and from the hydraulic chamber; a control unit for controlling the supply and discharge of brake fluid to and from the hydraulic chamber; and a unit for detecting the brake pressure in the hydraulic chamber. In a brake system comprising a first brake pressure detection unit, the control unit comprises a starting detection unit that detects when the vehicle starts moving after stopping based on the vehicle speed detected by the vehicle speed detection unit, a pressure reduction processing unit that operates the brake fluid pressure circuit to reduce the brake pressure in the fluid chamber when the starting detection unit detects when the vehicle starts moving, and a pressure increase processing unit that operates the brake pressure circuit to increase the brake pressure in the fluid chamber when the brake pressure detected by the first brake pressure detection unit falls below a preset first threshold pressure. [Effects of the Invention]

[0015] According to the present invention, when the vehicle is detected to be starting after being stopped, the brake fluid pressure circuit is activated to reduce the brake pressure in the fluid chamber provided in the disc brake, thereby quickly suppressing the generation of drag torque when starting after the brake is released. Furthermore, since the brake pressure in the fluid chamber is increased after being reduced, excessive piston return is suppressed, preventing any wasted time during the next brake operation and preventing a delay in brake operation. [Brief explanation of the drawing]

[0016] [Figure 1] Schematic cross-sectional view of the main components of a disc brake. [Figure 2] Configuration diagram of the brake control calculation unit [Figure 3] Diagram of the brake fluid pressure circuit and brake pedal mechanism. [Figure 4] Flowchart showing brake drag suppression control routine [Figure 5] Enlarged cross-sectional view showing the state of the piston seal when the brakes are applied. [Figure 6] Enlarged cross-sectional view showing the state of the piston seal when brake pressure is reduced. [Figure 7] Enlarged cross-sectional view showing the state of the piston seal after a slight increase in brake pressure. [Modes for carrying out the invention]

[0017] One embodiment of the present invention will be described below with reference to the drawings. The brake device according to this embodiment mainly consists of a disc brake 1 shown in Figure 1, a brake control calculation unit 41 shown in Figure 2, a brake fluid pressure circuit 11 shown in Figure 3, and a brake pedal mechanism 12.

[0018] FIG. 1 illustrates a caliper floating type disc brake 1. In this embodiment, the disc brakes 1 are respectively arranged on the four wheels on the front, rear, left and right. This disc brake 1 is mainly used as a service brake, but may also be used as a parking brake. This disc brake 1 includes a disc rotor 2, a brake caliper 3, an inner brake pad 4a, and an outer brake pad 4b.

[0019] The disc rotor 2 is connected to a wheel hub (not shown) and rotates integrally with the wheel. The brake caliper 3 is attached to the suspension via a mounting bracket (not shown). The brake caliper 3 has a caliper body 3a and a claw portion 3b. The caliper body 3a is disposed on the inner side constricted surface 2a side of the disc rotor 2.

[0020] The claw portion 3b straddles the disc rotor 2 from the caliper body 3a and faces the outer side constricted surface 2b of the disc rotor 2. In this embodiment, "inner" indicates the inner side in the vehicle body width direction, and "outer" indicates the outer side in the vehicle body width direction. Further, the mounting bracket supports the brake caliper 3 in a state movable in the axial direction of the disc rotor 2 via a pin mechanism (not shown).

[0021] The inner brake pad 4a is disposed between the caliper body 3a and the inner side constricted surface 2a of the disc rotor 2. The outer brake pad 4b is disposed between the claw portion 3b and the outer side constricted surface 2b of the disc rotor 2. The back surface of the inner brake pad 4a is fixed to the pressing surface of the caliper piston 5. The back surface of the outer brake pad 4b is fixed to the claw portion 3b. The caliper piston 5 is inserted into a cylinder (caliper cylinder) 3c formed in the caliper body 3a in a slidable state.

[0022] The space between the outer circumference of the pressing surface of the caliper piston 5 and the opening of the caliper cylinder 3c is sealed by a circular dust boot 7. This dust boot 7 prevents dust from entering the caliper cylinder 3c from the outside. This dust boot 7 is formed in a bellows shape and expands and contracts in accordance with the sliding motion of the caliper piston 5.

[0023] Furthermore, a seal groove 3d is formed in an annular shape on the inner circumference of the caliper cylinder 3c. The outer edge of the piston seal 8 is fitted into the seal groove 3d. This piston seal 8 is made from an elastic material such as EPMD (ethylene propylene rubber). The inner circumference of this piston seal 8 protrudes slightly inward from the inner circumference of the caliper cylinder 3c. The outer circumference of the caliper piston 5 slides against the inner circumference of this piston seal 8, sealing the gap between the caliper cylinder 3c and the caliper piston 5.

[0024] Furthermore, a closed hydraulic chamber 9 is defined by the caliper piston 5, caliper cylinder 3c, and piston seal 8. One end of a hydraulic passage 9a is open into this hydraulic chamber 9. The other end of this hydraulic passage 9a protrudes to the outside of the caliper body 3a. A brake hydraulic circuit (hydraulic unit) 11 is connected to the other end of the hydraulic passage 9a that protrudes to the outside. In addition, a brake pedal mechanism 12 is connected to this brake hydraulic circuit 11.

[0025] The brake pedal mechanism 12 is operated by the driver when they intend to decelerate the vehicle. As shown in Figure 3, the brake pedal mechanism 12 includes a tandem-type brake master cylinder (hereinafter simply referred to as "master cylinder") 13, a reservoir tank 14 attached to the master cylinder 13, and a brake pedal 16 connected to the master cylinder 13 via a brake booster 15. Brake fluid is stored in the reservoir tank 14. The brake pedal 16 is also connected to the brake booster 15 via an operating rod 17.

[0026] When the driver presses the brake pedal 16, the brake booster 15 doubles the force applied to the brake pedal 16, pressing the piston of the master cylinder 13. This pressurizes the brake fluid in the master cylinder 13, and the brake fluid in the brake fluid pressure circuit 11 is supplied to the hydraulic chamber 9 of the brake caliper 3. The hydraulic pressure supplied to the hydraulic chamber 9 presses the inner brake pad 4a via the caliper piston 5, and the floating action of the brake caliper 3 causes both brake pads 4a and 4b to press against the pressure-reducing surfaces 2a and 2b of the disc rotor 2.

[0027] Figure 3 illustrates the configuration of the brake fluid circuit 11. This brake fluid circuit 11 is already used in brake control systems such as ABS (Antilock Brake System) and VDC (Vehicle Dynamics Control).

[0028] This brake fluid pressure circuit 11 consists of two independent systems: a primary fluid pressure circuit 22 and a secondary fluid pressure circuit 23. The primary fluid pressure circuit 22 and the secondary fluid pressure circuit 23 are formed by cross piping or front-to-back piping. Since the primary fluid pressure circuit 22 and the secondary fluid pressure circuit 23 have the same configuration, the same reference numerals will be used below to simplify the explanation.

[0029] In the initial state when the brake fluid pressure circuit 11 is inactive, the pump motor 25 is stopped, and therefore the pump 24 is also stopped. In this state, when the driver presses the brake pedal 16, the brake fluid in the master cylinder 13 flows in the direction indicated by the solid arrow. That is, the brake fluid passes through the normally open atmospheric pressure valve 26, through the bifurcated passage, through the normally open holding valves 27a and 27b, and the hydraulic passage 9a, and flows into the hydraulic chamber 9 of the brake caliper 3.

[0030] When brake fluid is supplied to the hydraulic chamber 9, the pressure causes the caliper piston 5 and the caliper body 3a to move in opposite directions. As shown in Figure 1, the caliper piston 5 presses the inner brake pad 4a against the inner pressure surface 2a of the disc rotor 2. In reaction to this, the claw portion 3b, which is integrated with the caliper body 3a, presses the outer brake pad 4b against the outer pressure surface 2b of the disc rotor 2.

[0031] As a result, both pressure surfaces 2a and 2b of the disc rotor 2 are pressed against both brake pads 4a and 4b, and the brakes are applied to each wheel.

[0032] As shown by the arrows in Figure 5, when the caliper piston 5 slides toward the inner brake pad 4a, the inner circumference of the piston seal 8, which slides against the outer circumference of the caliper piston 5, elastically deforms in accordance with the movement of the caliper piston 5. Note that the amount of this elastic deformation increases as the amount of movement of the caliper piston 5 increases (stronger braking force).

[0033] On the other hand, when the driver releases the pressure on the brake pedal 16, the brake pressure in the hydraulic chamber 9 is reduced. Then, the restoring force of the piston seal 8 causes the caliper piston 5 to return, releasing the pressure applied by both brake pads 4a and 4b to the two pressure surfaces 2a and 2b of the disc rotor 2, and releasing the brakes on each wheel.

[0034] Incidentally, when releasing the brakes, if the elastic deformation of the piston seal 8 is large, it may be difficult to return the caliper piston 5 to its original position using only the restoring force of the piston seal 8. If the caliper piston 5 does not return to its original position, drag torque will be generated.

[0035] As will be described later, the brake control calculation unit 41 shown in Figure 2 controls the supply and discharge of brake fluid to and from the hydraulic chamber 9 by operating the actuators (valve actuators) of each valve 26, 27a, 27b, 28a, 28b provided in the brake hydraulic circuit 11, as well as the pump motor 25.

[0036] This brake control calculation unit 41 is composed of a microcontroller. The microcontroller includes a CPU, RAM, ROM, rewritable non-volatile memory (flash memory or EEPROM), and peripheral devices. The RAM of the microcontroller is provided as the CPU's work area, where various data from the CPU is temporarily stored. The ROM stores programs and fixed data necessary for the CPU to execute various processes. The CPU is also called an MPU (Microprocessor) or processor. Alternatively, a GPU (Graphics Processing Unit) or GSP (Graph Streaming Processor) may be used instead of the CPU. Alternatively, a selective combination of CPU, GPU, and GSP may be used.

[0037] A drag suppression control unit 41a is provided in this brake control calculation unit 41. This drag suppression control unit 41a has the function of assisting in the restoration of the piston seal 8 when the brake is released and suppressing the generation of drag torque.

[0038] The drag suppression control unit 41a uses the brake fluid pressure circuit 11 to assist in the restoration of the piston seal 8 when the brake is released.

[0039] The input side of the brake control calculation unit 41 is connected to the following sensors for detecting the generation of brake drag torque: a vehicle speed sensor 42 as a vehicle speed detection unit, a master pressure sensor 43 as a second brake pressure detection unit, a brake pressure sensor 44 as a first brake pressure detection unit, and a brake switch 45.

[0040] Here, the vehicle speed sensor 42 detects the vehicle speed. The vehicle speed sensor 42 may consist of wheel speed sensors installed on all four wheels. In this case, the vehicle speed sensor 42 detects the vehicle speed from the average value of the wheel speeds of each wheel detected by the wheel speed sensors. The master pressure sensor 43 detects the master pressure supplied from the master cylinder 13.

[0041] The brake pressure sensor 44 detects the pressure of the brake fluid supplied to the hydraulic chamber 9. The brake switch 45 is a switch that detects when the driver depresses the brake pedal 16. The brake switch 45 turns ON when the driver depresses the brake pedal 16 and turns OFF when the driver releases the brake pedal 16.

[0042] On the other hand, the output side of the brake control calculation unit 41 is connected to the actuators (valve actuators) of each valve 26, 27a, 27b, 28a, and 28b, which operate the brake fluid pressure circuit 11 when the brake is released, and the pump motor 25. The operation of the actuators of each valve 26, 27a, 27b, 28a, and 28b, and the pump motor 25 when the brake pressure is released will be described later.

[0043] The brake drag suppression control performed by the drag suppression control unit 41a is specifically processed according to the brake drag suppression control routine shown in Figure 4. This routine is executed at predetermined calculation cycles after the driver turns on the system.

[0044] When the system is started, the drag suppression control unit 41a first checks whether the brake switch 45 is ON or OFF (step S1). If the brake switch 45 is ON (YES), the driver is pressing down on the brake pedal 16. If the brake switch 45 is OFF (NO), the driver has released the brake pedal 16, and the routine is exited.

[0045] When the brake switch 45 is determined to be ON (step S1: YES), the skid suppression control unit 41a compares the master pressure Pms detected by the master pressure sensor 43 with the depression determination pressure Pmo (step S2). When the driver stops the vehicle, the driver tends to depress the brake pedal 16 relatively strongly. This depression determination pressure Pmo is a value for determining whether the driver has depressed the brake pedal 16 strongly when stopping the vehicle while decelerating. This depression determination pressure Pmo is set for each vehicle type in advance based on experiments or the like.

[0046] Then, when Pms≥Pmo (YES), the skid suppression control unit 41a determines that the driver is depressing the brake pedal 16 with a relatively strong force. Also, when Pms<Pmo (NO), the skid suppression control unit 41a determines that the driver is depressing the brake pedal 16 with a normal depressing force and exits the routine.

[0047] When the skid suppression control unit 41a determines that Pms≥Pmo (step S2: YES), it reads the vehicle speed Vs detected by the vehicle speed sensor 42 and determines whether the vehicle has stopped (step S3). Then, when the skid suppression control unit 41a determines that the vehicle is running (Vs>0: NO), it waits until the vehicle stops.

[0048] Also, when the skid suppression control unit 41a determines that the vehicle has stopped (Vs = 0: YES), it checks whether the brake switch 45 has operated to OFF (step S4). Note that when the system is turned off after the vehicle has stopped, this routine ends.

[0049] When the skid suppression control unit 41a determines that the brake switch 45 is continuously in the ON state (NO), it waits until the brake switch 45 operates to OFF. On the other hand, when the skid suppression control unit 41a determines that the brake switch 45 has operated to OFF (YES), it reads the vehicle speed Vs detected by the vehicle speed sensor 42 and checks whether the vehicle has started (step S5). Note that the processing in this step S5 corresponds to the start detection unit of the present invention.

[0050] Then, if the drag suppression control unit 41a determines that the vehicle is stopped (Vs=0) (step S5: NO), it waits until the vehicle starts moving. On the other hand, if the drag suppression control unit 41a determines that the vehicle has started moving (Vs>0) (YES), it executes control to reduce the brake pressure (step S6).

[0051] The driver keeps the brake pedal 16 pressed down while the vehicle is stopped. Then, when starting the vehicle, the driver releases the brake pedal 16 and presses the accelerator pedal. Thus, the driver's actions of releasing the brake pedal 16 and then pressing the accelerator pedal are continuous. Therefore, if the caliper piston 5 does not return to its original position immediately after the driver releases the brake pedal 16, drag torque will be generated.

[0052] In step S6, when the driver attempts to start the vehicle, the drag suppression control unit 41a quickly reduces the brake pressure Pbr in the hydraulic chamber 9. As a control to reduce the brake pressure, the drag suppression control unit 41a first turns on the pump motor 25. Next, the drag suppression control unit 41a closes the normally open holding valves 27a and 27b and opens the normally closed pressure reducing valves 28a and 28b.

[0053] When the pump motor 25 is turned ON, the pump 24 is driven, and as shown by the dashed arrow in Figure 3, the brake fluid stored in the hydraulic chamber 9 of the brake caliper 3 is drawn up to the pump 24 via the pressure reducing valves 28a and 28b and the reservoir 29. The drawn-up brake fluid passes through the damper chamber 31 and is returned to the master cylinder 13 side via the normal pressure valve 26. As a result, the brake pressure in the hydraulic chamber 9 is actively reduced, and the caliper piston 5 is returned. This assists in the restoration of the piston seal 8, and the generation of drag torque is quickly suppressed.

[0054] Thereafter, the drag torque suppression control unit 41a compares the brake pressure Pbr in the hydraulic chamber 9 detected by the brake pressure sensor 44 with a preset first threshold pressure Pb1 (step S7). This first threshold pressure Pb1 is a fixed value preset for each vehicle type. To quickly suppress the drag torque, it is necessary to reduce the brake pressure Pbr in the hydraulic chamber 9 until it becomes lower than the brake pressure when the driver releases the depression of the brake pedal 16.

[0055] The first threshold pressure Pb1 is the brake pressure required to release the clamping force on the clamping surfaces 2a and 2b of the brake pads 4a and 4b before the vehicle speed at start-up reaches a predetermined vehicle speed (for example, 5 [Km / h]). This first threshold pressure Pb1 is a fixed value preset for each vehicle type based on experiments and the like in advance.

[0056] When Pbr≥Pb1 (step S7: NO), the drag torque suppression control unit 41a returns to step S6 and repeatedly executes the brake pressure reduction process. When the drag torque suppression control unit 41a detects Pbr<Pb1 (step S7: YES), it executes a fine pressure increase process to slightly increase the brake pressure (step S8). The processes in steps S6 and S7 correspond to the pressure reduction processing unit of the present invention.

[0057] If the pressure in the hydraulic chamber 9 is rapidly reduced in the brake hydraulic circuit 11, the caliper piston 5 will be in a position where it has retracted too far from its original position. Then, as shown in FIG. 6, the inner circumference of the piston seal 8 that slidably contacts the caliper piston 5 elastically deforms following the retraction of the caliper piston 5. Due to this elastic deformation, a restoring force remains as internal stress in the piston seal 8, resulting in a decrease in durability.

[0058] Also, due to excessive return of the caliper piston 5, the gaps between the brake pads 4a, 4b and the pressed surfaces 2a, 2b of the disk rotor 2 become large. When the gaps between the brake pads 4a, 4b and the pressed surfaces 2a, 2b of the disk rotor 2 become large, an ineffective time occurs when the driver depresses the brake pedal 16 next time. When an ineffective time occurs during the braking operation, a delay in the operation of the brake occurs, and the braking effect deteriorates. Also, the delay in the operation of the brake causes a sense of discomfort to the driver during the brake operation.

[0059] Therefore, when the drag suppression control unit 41a detects that Pbr < Pb1 (step S7: YES), it executes a process of slightly increasing the brake pressure Pbr (step S8). When the drag suppression control unit 41a slightly increases the brake pressure Pbr, first, it continues the ON state of the pump motor 25 from the process of step S6. Next, the drag suppression control unit 41a closes the constant pressure valve 26. Further, the drag suppression control unit 41a opens the holding valves 27a, 27b and closes the pressure reducing valves 28a, 28b.

[0060] Then, the brake fluid stored in the reservoir 29 is supplied to the hydraulic chambers 9 of each brake caliper 3 via the pump 24. As a result, due to the pressure of the brake fluid supplied to the hydraulic chamber 9, the caliper piston 5 and the caliper body 3a are separated from each other. Then, the caliper piston 5 and the claw portion 3b move in the direction of their original positions, and the gaps between the brake pads 4a, 4b and the pressed surfaces 2a, 2b of the disk rotor 2 become narrow.

[0061] Thereafter, the drag suppression control unit 41a compares the brake pressure Pbr detected by the brake pressure sensor 44 with a second threshold pressure (step S9). The second threshold pressure is a value (for example, 1 [MPa]) for returning the caliper piston 5 to its original position (initial position). The second threshold pressure is obtained in advance through experiments or the like and is set for each vehicle type.

[0062] Then, when Pbr < Pb2 (step S9: NO), the drag suppression control unit 41a repeatedly executes the process of slightly increasing the brake pressure. When the drag suppression control unit 41a detects that Pbr ≥ Pb2 (step S9: YES), it turns off the actuators of the pump motor 25 and the valves 26, 27a, 27b, 28a, 28b (step S10) and exits the routine.

[0063] As a result, the brake hydraulic circuit 11 returns to the initial non-operating state. Also, as shown in FIG. 7, the caliper piston 5 is returned to its original position, and the restoring force (internal stress) remaining in the piston seal 8 is depressurized. Note that the processes in steps S8 to S10 correspond to the pressure increasing processing unit of the present invention.

[0064] Thus, according to the present embodiment, after the driver strongly presses the brake pedal 16 to stop the vehicle and then attempts to start the vehicle, the drag suppression control unit 41a operates the brake hydraulic circuit 11 to quickly reduce the brake pressure in the hydraulic chamber 9 of the brake caliper 3, so that the generation of drag torque can be suppressed.

[0065] Also, since the brake hydraulic circuit 11 quickly reduces the brake pressure in the hydraulic chamber 9 of the brake caliper 3, even if the resistance when returning the caliper piston 5 increases due to the rigidity of the brake caliper 3 and brake pads 4a, 4b or the deterioration of the piston seal 8, etc., the generation of drag torque can be quickly suppressed.

[0066] Furthermore, after the brake in the hydraulic chamber is depressurized by the brake hydraulic circuit 11 and then slightly increased, over-return of the caliper piston 5 is suppressed, and the caliper piston 5 can be quickly returned to its original position. Furthermore, since the caliper piston 5 can be quickly returned to its original position, no invalid time occurs in the next brake operation, and brake operation delay can be prevented.

[0067] Furthermore, the present invention is not limited to the embodiments described above. For example, the disc brake 1 is not limited to a floating caliper type, but may also be a piston-opposed type. [Explanation of Symbols]

[0068] 1… Disc brakes, 2…Disc rotor, 2a...Inner side narrowed pressure surface, 2b...Outer side narrow pressure surface, 3...Brake caliper, 3a... Caliper body, 3b...Claw part, 3c... Caliper cylinder, 3D... seal groove, 4a... Inner brake pads, 4b...Outer brake pads, 5... Caliper piston, 7... Dust boots, 8... Piston seal, 9... Hydraulic chamber, 9a... Hydraulic passage, 11...Brake fluid pressure circuit, 12...Brake pedal mechanism, 13…Master cylinder, 14... Reservoir tank, 15...Brake booster, 16...Brake pedal, 17…Operating rod, 22... Primary hydraulic circuit, 23...Secondary hydraulic circuit, 24... pump, 25... Pump motor, 26...Normal pressure valve, 27a, 27b... retaining valves, 28a, 28b... pressure reducing valves, 29...Reservoir, 31...Dump room, 41...Brake control calculation unit, 41a... Drag suppression control unit, 42... Vehicle speed sensor, 43…Master pressure sensor, 44...Brake pressure sensor, 45...Brake switch, Pb1...First threshold pressure, Pb2... Second threshold pressure, Pbr...Brake pressure, Pmo... Step detection pressure, PMS... Master pressure, Vs…vehicle speed

Claims

1. A vehicle speed detection unit that detects the vehicle's speed, A disc brake comprising a piston that presses a brake pad against a disc rotor, a cylinder through which the piston is inserted, and a piston seal fitted into a seal groove formed in the cylinder, the inner circumference of which is in sliding contact with the piston, wherein a hydraulic chamber is defined by the piston, the cylinder, and the piston seal, A brake fluid pressure circuit for supplying and discharging brake fluid to the aforementioned hydraulic chamber, A control unit that controls the supply and discharge of the brake fluid to and from the hydraulic chamber, A first brake pressure detection unit for detecting the brake pressure in the hydraulic chamber and In a braking system equipped with, The control unit, A starting detection unit detects the vehicle starting after it has stopped, based on the vehicle speed detected by the vehicle speed detection unit. When the starting detection unit detects the vehicle starting, the pressure reduction processing unit operates the brake fluid pressure circuit to reduce the brake pressure in the fluid pressure chamber, When the brake pressure detected by the first brake pressure detection unit falls below a preset first threshold pressure, the brake fluid pressure circuit is activated to increase the brake pressure in the fluid chamber. A vehicle braking system characterized by comprising the following:

2. The pressure boosting unit stops the operation of the brake fluid pressure circuit when the brake pressure detected by the first brake pressure detection unit becomes higher than a preset second threshold pressure. The brake device for a vehicle according to claim 1, characterized in that it is a brake device for a vehicle.

3. The brake pedal mechanism, in which the driver operates the brakes, A second brake pressure detection unit for detecting the brake pressure generated in the brake pedal mechanism, Furthermore, The pressure reduction processing unit reduces the brake pressure in the hydraulic chamber when the brake pressure detected by the second brake pressure detection unit exceeds a preset depression determination pressure. The brake device for a vehicle according to claim 1, characterized in that it is a brake device for a vehicle.

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