Brake system

Abstract

In the present invention, a simpler configuration enables control to be performed more reliably and maintenance to be performed more straightoforwardly. A brake system includes one brake caliper, one drive device, and one or more hoses. The drive device comprises a container in which is formed a hollow storage part of prescribed internal volume that is filled with brake fluid, a first internal volume change means for changing the internal volume of the storage part by entering and exiting the storage part, a first drive means for electrically driving the first internal volume change means so as to enter and exit the storage part, a second internal volume change means for changing the internal volume of the storage part by entering and exiting the storage part, and a second drive means for electrically driving the second internal volume change means so as to enter and exit the storage part. The cross-sectional area of the second internal volume change means, which is the cross-sectional area of a cross section orthogonal to the direction of displacement when the second internal volume change means enters and exits the storage part, is less than the cross-sectional area of a cross section of the first internal volume change means, which is the cross-sectional area of a cross section orthogonal to the direction of displacement when the first internal volume change means enters and exits the storage part. The brake fluid is sealed by the drive device, the brake caliper, and the hose(s), and is isolated from the outside.

Description

Brake system

[0001] The present invention relates to a brake system, and more particularly to a brake system for a disc brake.

[0002] Disc brakes are currently widely used as brakes for automobiles and other vehicles.

[0003] Vehicles are equipped with brake systems that detect wheel slippage during emergency braking or braking on slippery roads and control the pressure of brake fluid (hereinafter also referred to as brake fluid) to prevent wheel slippage caused by wheel lock, thereby ensuring directional stability and maneuverability while moving and improving braking performance. That is, wheel speed (rotational speed) is detected by signals from wheel speed sensors, wheel rotational status is detected, wheel slip status is measured or predicted, and the hydraulic system is controlled to prevent the wheels from locking. One hydraulic system control device is a motor direct-acting control device that controls brake fluid pressure by driving a piston with an electric motor.

[0004] For example, one system adds signals that are functions of wheel deceleration, wheel slip, the integral of the slip, and vehicle deceleration, and generates a pressure drop pulse when the sum reaches an instability threshold (see, for example, US Pat. No. 5,649,399).

[0005] When the wheel deceleration is measured and only one wheel falls below the current speed threshold, the wheel braking start threshold is raised to prevent braking start due to this, thereby selecting external disturbance factors due to the road.

[0006] When the wheels are rotated and the brakes are applied, the wheels lock completely, and the slip ratio between the wheels and the road surface changes until the vehicle comes to a stop. The brake fluid pressure is also controlled so that the coefficient of friction between the road surface and the wheels (tires) remains at a constant (ideal) value. In other words, the brake fluid pressure is increased until the slip ratio reaches the ideal slip ratio, and once it exceeds the ideal slip ratio, the brake fluid pressure is reduced to maintain the maximum value of the friction coefficient, shortening the braking distance and ensuring vehicle stability and maneuverability within the range of a high coefficient of friction for sideslip.

[0007] DE 3841977 A1

[0008] However, while modern automobiles are generally equipped with methods for controlling and executing vehicle behavior, such as deceleration, tire spin, and skidding, these systems typically rely on a pump in the ABS (Anti-lock Brake System) actuator to pump brake fluid from the wheel's brake calipers back into a master cylinder, controlling the hydraulic pressure. In two-channel systems that link the front and rear wheels or systems without G (acceleration) sensors, the system adjusts the grip of the other wheels to the wheel with the lowest grip (friction), reducing the overall braking force of the vehicle and resulting in insufficient braking. In addition, differences in braking force can occur due to component precision and aging. Furthermore, even in systems that can independently control all wheels, as mentioned above, the cylinder in the ABS actuator transmits pressure to the front, rear, left, and right brake calipers via hydraulic ducts and hydraulic tubing using brake fluid as a medium, which can lead to delays and lags in operation due to hydraulic duct and tubing expansion and other factors, making rapid control difficult.

[0009] Modern vehicle braking systems not only slow and stop the vehicle, but also perform functions such as vehicle stability control, skid prevention, brake distribution control, and traction control. Furthermore, collision safety devices are also activated to provide control during and after a vehicle collision. These controls require the installation and control of front and rear brake force distribution control devices, left and right brake force distribution devices, booster pumps, booster control valves, accumulators, and other devices, and transmit pressure via hydraulic ducts and hydraulic tubing. Therefore, expansion of hydraulic ducts and tubing and other factors can cause delays and stagnation in operation, making prompt control difficult and complicated. Furthermore, the increase in control equipment not only increases production costs, but also increases the weight of the vehicle and makes maintenance and inspection more complicated.

[0010] The present invention has been made in view of the above circumstances, and aims to provide a system with a simpler configuration, more reliable control, and easier maintenance.

[0011] A brake system according to one aspect of the present invention includes a brake caliper for a disc brake, the brake caliper pressing a brake pad against a brake disc with brake fluid filled therein, a drive unit applying pressure to the brake fluid to send the brake fluid to the brake caliper or to suck the brake fluid from the brake caliper, and one or more hoses connecting the brake caliper and the drive unit through the brake fluid to transmit the brake fluid pressure. The drive unit includes a container having a hollow storage section of a predetermined internal volume filled with brake fluid, and a fluid supply section for supplying the fluid to and from the storage section. The system includes a first internal volume changing means for changing the internal volume, a first drive means for electrically driving the first internal volume changing means so that it moves in and out of the storage section, a second internal volume changing means for moving in and out of the storage section and changing the internal volume of the storage section, and a second drive means for electrically driving the second internal volume changing means so that it moves in and out of the storage section, and the cross-sectional area of ​​the second internal volume changing means, which is perpendicular to the direction of displacement when it moves in and out of the storage section, is smaller than the cross-sectional area of ​​the first internal volume changing means, which is perpendicular to the direction of displacement when the first internal volume changing means moves in and out of the storage section, and the brake fluid is sealed by the drive unit, brake caliper, and hose and isolated from the outside.

[0012] The first internal volume changing means and the first driving means can be used to adjust the gap between the brake pad and the brake disc.

[0013] The second internal volume changing means and the second driving means can be used for braking.

[0014] The first internal volume changing means can incorporate the second internal volume changing means and the second driving means.

[0015] The drive device can further be provided with a third internal volume changing means that moves in and out of the storage section to change the internal volume of the storage section, and a third drive means that electrically drives the third internal volume changing means so that the third internal volume changing means moves in and out of the storage section, and the cross-sectional area of ​​the third internal volume changing means that is perpendicular to the direction of displacement when the third internal volume changing means moves in and out of the storage section is smaller than the cross-sectional area of ​​the second internal volume changing means that is perpendicular to the direction of displacement when the second internal volume changing means moves in and out of the storage section.

[0016] The third internal volume changing means and the third driving means can be used to control braking force in an antilock brake system, an electronically controlled brake system, a traction control system, or an anti-skid device.

[0017] The drive device may further be provided with a first valve at the end of the hose on the drive device side for stopping the flow of brake fluid from the storage section into the hose and a second valve for stopping the flow of brake fluid from the hose to the storage section.

[0018] The storage section of the drive device may further be provided with a partition that separates the brake fluid flowing from the first valve into the storage section from the brake fluid flowing from the storage section into the second valve.

[0019] Two hoses may be provided, and the drive unit may further be provided with a first valve at the end of one of the two hoses that faces the drive unit to stop the flow of brake fluid from the storage section into one of the hoses, and a second valve at the end of the other of the two hoses that faces the drive unit to stop the flow of brake fluid from the other hose into the storage section.

[0020] As described above, according to the present invention, a simpler configuration allows for more reliable control and easier maintenance.

[0021] Fig. 1 is a block diagram showing an example of the configuration of a vehicle brake system 11. Fig. 2 is a cross-sectional view showing the details of the configuration of the brake system 21. Fig. 3 is a block diagram explaining the hardware configuration of an ECU 22. Fig. 4 is a block diagram showing the configuration of functions realized by the ECU 22 executing a program. Fig. 5 is a flowchart explaining the process of adjusting the gap between a brake disc 124 and a brake pad 133. Fig. 6 is a cross-sectional view showing the details of the configuration of a brake system 221. Fig. 7 is a cross-sectional view showing the details of the configuration of a brake system 301. Fig. 8 is a flowchart explaining the process of replacing brake fluid 82. Fig. 9 is a cross-sectional view showing the details of the configuration of a brake system 401. Fig. 10 is a cross-sectional view showing the details of the configuration of a brake system 501.

[0022] A brake system according to an embodiment of the present invention will now be described with reference to FIGS.

[0023] Fig. 1 is a block diagram showing an example of the configuration of a vehicle brake system 11. The example of the vehicle brake system 11 shown in Fig. 1 generates braking force in brake discs provided on each wheel of a four-wheel vehicle. The vehicle brake system 11 is configured to include brake systems 21-1 to 21-4, an ECU (Electronic Control Unit) 22, a brake pedal sensor 23, and a sensor 24.

[0024] The brake systems 21-1 to 21-4 generate braking forces on brake discs provided for the respective wheels of the vehicle. The ECU 22 includes a so-called processor (computer) and controls and drives each of the brake systems 21-1 to 21-4 by referring to signals from the brake pedal sensor 23, the sensor 24, and each of the brake systems 21-1 to 21-4.

[0025] The brake pedal sensor 23 detects the amount of depression of the brake pedal (amount of brake pedal displacement), the force with which the brake pedal is depressed, the acceleration of the brake pedal when the vehicle driver depresses the brake pedal to generate a braking force in the vehicle brake system 11, and supplies signals indicating the detected amount of depression of the brake pedal (amount of brake pedal displacement), the force with which the brake pedal is depressed, the acceleration of the brake pedal when depressed, etc. to the ECU 22.

[0026] The sensor 24 is one or more sensors, including dedicated sensors, cameras, radar, or LiDAR (Laser Imaging Detection and Ranging), and is provided at various locations on the vehicle. The sensor 24 detects vehicle or road conditions, such as vehicle speed, outside vehicle temperature, atmospheric pressure, weather conditions (e.g., whether it is raining or not), vehicle inclination, the gradient of the road on which the vehicle is located, steering angle, road surface conditions, vehicle acceleration (six-axis acceleration), and the rotation speed of each wheel, and supplies signals indicating the detected conditions to the ECU 22. Note that, among multiple controllers (processors) that control the vehicle, a controller (processor) other than the ECU 22 may supply signals indicating the vehicle or road conditions to the ECU 22.

[0027] The brake system 21-1 includes a drive unit 41-1, a brake caliper 42-1, and a hose 43-1. The brake system 21-1 is provided for one specific wheel of the vehicle. The drive unit 41-1 drives the brake caliper 42-1 under the control and drive of the ECU 22. The drive unit 41-1 applies pressure to the brake fluid to send the brake fluid to the brake caliper 42-1 or to suck the brake fluid from the brake caliper 42-1. The brake caliper 42-1 generates braking force by pressing the brake pads against the brake disc using the brake fluid pressurized by the drive unit 41-1. In other words, the brake caliper 42-1 is a brake caliper for a disc brake, and presses the brake pads against the brake disc using the brake fluid filled therein. The hose 43-1 is a pipe through which the brake fluid passes. The hose 43-1 is a so-called brake hose, and connects the drive unit 41-1 and the brake caliper 42-1. That is, the hose 43-1 connects the brake caliper 42-1 and the drive unit 41-1 through the brake fluid so as to transmit the pressure of the brake fluid.

[0028] The ECU 22 controls and drives the drive unit 41-1 via a cable 31-1, which is an electric wire connecting the ECU 22 and the drive unit 41-1. The brake caliper 42-1 supplies a signal indicating the state of the brake caliper 42-1 to the ECU 22 from a sensor (described later) built into the brake caliper 42-1 via the cable 32-1, which is an electric wire connecting the ECU 22 and the brake caliper 42-1.

[0029] Similarly, the brake systems 21-2 to 21-4 include drive units 41-2 to 41-4, brake calipers 42-2 to 42-4, and hoses 43-2 to 43-4, respectively. Each of the brake systems 21-2 to 21-4 is provided for one predetermined wheel of the vehicle.

[0030] The drive units 41-2 to 41-4 drive the brake calipers 42-2 to 42-4, respectively, under the control and drive of the ECU 22. The drive units 41-2 to 41-4 apply pressure to the brake fluid to send the brake fluid to the brake calipers 42-2 to 42-4, respectively, or draw the brake fluid from the brake calipers 42-2 to 42-4, respectively. The brake calipers 42-2 to 42-4 pressurize the brake fluid against the brake discs, respectively, to generate braking force, using the brake fluid pressurized by the drive units 41-2 to 41-4, respectively. In other words, the brake calipers 42-2 to 42-4 are brake calipers for disc brakes, and press the brake pads against the brake discs using the brake fluid filled therein. The hoses 43-2 to 43-4 are pipes through which brake fluid passes. The hoses 43-2 to 43-4 are so-called brake hoses, and connect the drive units 41-2 to 41-4 to the brake calipers 42-2 to 42-4, respectively. That is, the hoses 43-2 to 43-4 connect the brake calipers 42-2 to 42-4 to the drive units 41-2 to 41-4, respectively, through the brake fluid so as to transmit the pressure of the brake fluid.

[0031] The ECU 22 controls and drives each of the drive units 41-2 to 41-4 via cables 31-2 to 31-4, which are electric wires connecting the ECU 22 to each of the drive units 41-2 to 41-4. The brake calipers 42-2 to 42-4 supply signals indicating the state of each of the brake calipers 42-2 to 42-4 to the ECU 22 from sensors (described later) built into each of the brake calipers 42-2 to 42-4 via cables 32-2 to 32-4, which are electric wires connecting the ECU 22 to each of the brake calipers 42-2 to 42-4.

[0032] Hereinafter, when there is no need to distinguish between the brake systems 21-1 to 21-4, they will simply be referred to as brake systems 21. Furthermore, hereinafter, when there is no need to distinguish between the drive units 41-1 to 41-4, they will simply be referred to as drive units 41. hereinafter, when there is no need to distinguish between the brake calipers 42-1 to 42-4, they will simply be referred to as brake calipers 42. Furthermore, hereinafter, when there is no need to distinguish between the hoses 43-1 to 43-4, they will simply be referred to as hoses 43. Furthermore, hereinafter, when there is no need to distinguish between the cables 31-1 to 31-4, they will simply be referred to as cables 31. hereinafter, when there is no need to distinguish between the cables 32-1 to 32-4, they will simply be referred to as cables 32.

[0033] FIG. 2 is a cross-sectional view showing the details of a brake system 21, an example of a brake system. The brake system 21 includes a drive unit 41, a brake caliper 42, and a hose 43. The drive unit 41 includes a sealed container 61, a clearance adjuster 62, and a braking pressure generator 63. The sealed container 61 hermetically contains brake fluid 82, excluding the connected hose 43. That is, the brake fluid 82 flows into and out of the sealed container 61 only through the hose 43. The sealed container 61 is made of a highly rigid and strong material, such as metal, resin, or a composite material, that can withstand high pressure. The sealed container 61 includes a hollow storage section 81 having a predetermined internal volume and filled with brake fluid 82. The volume of the storage section 81 of the sealed container 61 is larger than the volume of a cylinder 141 (described below) of the brake caliper 42. The outer shape of the sealed container 61 or the shape of the storage section 81 may be any desired shape.

[0034] Brake fluid 82, also referred to as brake oil, is a liquid filled in storage section 42, hose 43, and cylinder 141 (described later) of brake caliper 42. For example, brake fluid 82 is a glycol-based liquid whose main component is polyethylene glycol monoether or a silicone-based liquid whose main component is dimethylpolysiloxane.

[0035] The gap adjuster 62 increases or decreases its own volume in response to power or an electrical signal supplied from the ECU 22 via a cable 31, thereby changing the effective volume of the storage section 81 of the sealed container 61, thereby applying pressure to the brake fluid 82 stored in the storage section 81 of the sealed container 61 and sending the brake fluid 82 to the brake caliper 42 or sucking the brake fluid 82 from the brake caliper 42 through a hose 43.

[0036] In the brake system 21, a braking force is generated by friction caused by pressing a piston 132 installed in the brake caliper 42 against the brake disc 124 with a brake pad 133. As a result, a certain amount of wear occurs in the brake pad 133. As the brake pad 133 wears, the piston 132 needs to move the brake pad 133 closer to the brake disc 124 in order to press the brake disc 124. As the position of the piston 132 moves, the volume of the brake fluid 82 in the cylinder 141 of the brake caliper 42 increases. Therefore, to compensate for the increase in the brake fluid 82, it is necessary to add more brake fluid 82 to the cylinder 141 of the brake caliper 42.

[0037] 2, in the brake system 21, the brake fluid 82 is sealed by the drive unit 41, the brake caliper 42, and the hose 43 and isolated from the outside. Therefore, the volume of the brake fluid 82 stored in the brake system 21, which is isolated from the outside and sealed, is constant. As described above, the clearance adjuster 62 is provided in the drive unit 41 to compensate for the increase in the volume of the brake fluid 82 in the cylinder 141 of the brake caliper 42 that occurs as the brake pads 133 wear.

[0038] The gap adjuster 62 includes a piston 91, an actuator 92, and a frame 93. The piston 91 enters and leaves the storage section 81 of the sealed container 61. The piston 91 is formed of a highly rigid and strong material such as metal, resin, or a composite material. For example, the piston 91 is formed into a cylindrical shape from steel. For example, the piston 91 is formed into a cylindrical shape from steel, with the storage section 81 side being hemispherical. The shape of the piston 91 can be any desired shape, such as a prismatic shape, a pyramidal shape, a spherical shape, a hemispherical shape, or an oblong shape.

[0039] The actuator 92 electrically drives the piston 91 to move in and out of the storage section 81 of the sealed container 61 using power or an electric signal supplied from the ECU 22 via the cable 31. In other words, the actuator 92 displaces the piston 91 to move in and out of the storage section 81 of the sealed container 61. For example, the actuator 92 is a linear actuator. That is, the actuator 92 linearly displaces the piston 91 to move in and out of the storage section 81. For example, the actuator 92 is made up of an electric motor and a ball screw and drives the piston 91. Alternatively, for example, the actuator 92 is made up of an electric motor and a rack and pinion and drives the piston 91.

[0040] The frame 93 supports the piston 91 and the actuator 92. The frame 93 is made of a highly rigid and strong material such as metal, resin, or composite material.

[0041] The brake pressure generator 63 increases or decreases its own volume in response to power or an electrical signal supplied from the ECU 22 via a cable 31, thereby changing the effective volume of the storage section 81 of the sealed container 61, thereby applying pressure to the brake fluid 82 stored in the storage section 81 of the sealed container 61 and sending the brake fluid 82 to the brake caliper 42 or sucking the brake fluid 82 from the brake caliper 42 through the hose 43.

[0042] The braking pressure generator 63 includes a piston 101, an actuator 102, and a frame 103. The piston 101 enters and leaves the storage section 81 of the sealed container 61. The piston 101 is formed of a highly rigid and strong material such as metal, resin, or a composite material. For example, the piston 101 is formed into a cylindrical shape from steel. For example, the piston 101 is formed into a cylindrical shape from steel, with the storage section 81 side being hemispherical. The shape of the piston 101 can be any desired shape, such as a prismatic shape, a pyramidal shape, a spherical shape, a hemispherical shape, or an oblong shape.

[0043] The volume of piston 101 is smaller than the volume of piston 91. Furthermore, the cross-sectional area of ​​piston 101, which is perpendicular to the direction of displacement when piston 91 moves in and out of storage section 81, is smaller than the cross-sectional area of ​​piston 91, which is perpendicular to the direction of displacement when piston 91 moves in and out of storage section 81. In this case, for example, the cross-sectional area refers to the maximum cross-sectional area. Furthermore, for example, the cross-sectional area refers to the cross-sectional area at a position where piston 91 or piston 101, respectively, protrudes from frame 93 or frame 103 by a predetermined length (for example, a reference position for each operation).

[0044] In this way, as the piston 91 is displaced, a larger amount of brake fluid 82 can be sent from the drive device 41 to the brake caliper 42, or a larger amount of brake fluid 82 can be sucked from the brake caliper 42 into the drive device 41. Also, as the piston 101 is displaced, a higher pressure can be applied to the piston 132 of the brake caliper 42.

[0045] The actuator 102 electrically drives the piston 101 to move in and out of the storage section 81 of the sealed container 61 using power or an electric signal supplied from the ECU 22 via the cable 31. In other words, the actuator 102 displaces the piston 101 to move in and out of the storage section 81 of the sealed container 61. For example, the actuator 102 is a linear actuator. That is, the actuator 102 linearly displaces the piston 101 to move in and out of the storage section 81. For example, the actuator 102 is made up of an electric motor (motor) and a ball screw and drives the piston 101. For example, the actuator 102 is made up of an electric motor (motor) and a rack and pinion and drives the piston 101.

[0046] The frame 103 supports the piston 101 and the actuator 102. The frame 103 is made of a highly rigid and strong material such as metal, resin, or composite material.

[0047] The braking pressure generator 63 is disposed in the storage section 81 of the sealed container 61 so as not to interfere with the gap adjuster 62. That is, the gap adjuster 62 and the braking pressure generator 63 independently move the piston 91 and the piston 101 in and out of the storage section 81 of the sealed container 61, respectively.

[0048] The brake caliper 42 is a brake caliper for a disc brake provided on each wheel as a braking device for the vehicle. The brake caliper 42 is fixed to the vehicle body by a mounting bracket 122. More specifically, the brake caliper 42 is a so-called floating type (floating type / single-sided type) disc brake caliper that is supported on the mounting bracket 122 by a slide pin 123 of the mounting bracket 122 so as to be displaceable in the longitudinal direction of the slide pin 123.

[0049] The brake caliper 42 clamps a brake disc (rotor) 124, generating friction and resistance to the rotation of the brake disc 124. The brake disc 124 is rotatably supported on the vehicle by a hub 125. A wheel 126, on which a tire (not shown) is mounted, is fixed to the hub 125. In other words, the brake disc 124 is fixed to the wheel 126 in the direction of rotation. The resistance generated against the rotation of the brake disc 124 is transmitted to the wheel 126 and the tire, thereby generating a braking force on the vehicle.

[0050] The brake caliper 42 includes a cylinder body 131, a piston 132, a brake pad 133, and a sensor 134. Note that a description of piston seals or piston boots, pin boots, pad clips, shims, etc. will be omitted.

[0051] The cylinder body 131 supports the piston 132, the brake pads 133, and the sensor 134. The cylinder body 131 is formed to have high mechanical rigidity so that it is less likely to deform even when pressure or force is applied to the piston 132, the brake pads 133, the brake fluid 82, and the sensor 134. For example, the cylinder body 131 is formed from a metal material such as an aluminum alloy or iron.

[0052] The cylinder body 131 displaceably houses the piston 132. The cylinder body 131 also displaceably supports the brake pads 133 so that when the piston 132 displaces, the brake pads 133 also displace in accordance with the piston 132.

[0053] A cylinder 141 is formed in the cylinder body 131. The cylinder 141 is formed in a cylindrical shape with an inner diameter corresponding to the outer diameter of the piston 132. Because the inner diameter of the cylinder 141 corresponds to the outer diameter of the piston 132, the brake fluid 82 does not leak even when pressure is applied to the brake fluid 82.

[0054] The piston 132 is a so-called caliper piston and has a cylindrical outer shape. For example, the piston 132 is formed in a hollow cylindrical shape with a section inside that closes toward the bottom.

[0055] The brake pads 133 are friction members that sandwich both sides of the brake disc 124 when pressed by the piston 132, generating a friction force.

[0056] The sensor 134 is provided in the cylinder body 131. For example, the sensor 134 is provided so as to be in contact with the cylinder 141 of the cylinder body 131. The sensor 134 is formed of a piezoelectric sensor or the like, and detects the pressure of the brake fluid 82. The sensor 134 supplies a signal indicating the pressure of the brake fluid 82 to the ECU 22 via the cable 32.

[0057] The sensor 134 may be a magnetic sensor or the like that detects the position of the piston 132. In this case, the sensor 134 supplies a signal indicating the position of the piston 36 to the ECU 22 via the cable 32. The sensor 134 may be a thermistor or the like that detects the temperature of the brake fluid 82. In this case, the sensor 134 supplies a signal indicating the temperature of the brake fluid 82 to the ECU 22 via the cable 32.

[0058] Further, as the sensors 134, a sensor for detecting the position of the piston 132, a sensor for detecting the pressure of the brake fluid 82, and a sensor for detecting the temperature of the brake fluid 82 may be provided in the cylinder body 131, respectively.

[0059] More specifically, the hose 43 connects the storage section 81 of the drive unit 41 and the cylinder 141 of the cylinder body 131 .

[0060] Next, a description will be given of the hardware configuration of the ECU 22. Fig. 3 is a block diagram illustrating the hardware configuration of the ECU 22. The ECU 22 is a so-called computer.

[0061] In the ECU 22 , a CPU (Central Processing Unit) 181 , a ROM (Read Only Memory) 182 , and a RAM (Random Access Memory) 183 are interconnected by a bus 184 .

[0062] An input / output interface 185 is also connected to the bus 184. Connected to the input / output interface 185 are an input unit 186 for inputting signals from the brake pedal sensor 23, the sensor 24, and the brake calipers 42-1 to 42-4, a drive unit 187 for driving the drive devices 41-1 to 41-4, a storage unit 188 formed of a nonvolatile memory or the like, and a communication unit 189 formed of a network interface or the like.

[0063] In the ECU 22 (computer) configured as described above, the CPU 181 loads a program stored in the storage unit 188, for example, into the RAM 183 via the input / output interface 185 and the bus 184, and executes the program, thereby performing a series of processes described below.

[0064] The program executed by the ECU 22 (CPU 181) is stored in a removable medium, which is a package medium such as a semiconductor memory, or is provided via the communication unit 189 from a wired or wireless transmission medium such as a local area network, the Internet, or digital satellite broadcasting.

[0065] The program can be installed in the computer by receiving it via a wired or wireless transmission medium at the communication unit 189 and recording it in the storage unit 188. Alternatively, the program can be pre-installed in the computer by storing it in the ROM 182 or the storage unit 188 in advance.

[0066] That is, the ECU 22 (computer) executes the installed programs to realize the functions described below.

[0067] Next, the functions of the ECU 22 that executes the program will be described. FIG. 4 is a block diagram showing the configuration of functions realized by the ECU 22, which is a computer, executing the program. The ECU 22's execution of the program realizes a clearance adjustment control unit 201, a braking force generation control unit 202, a control force generation control unit 203, and a fluid replacement control unit 204. The clearance adjustment control unit 201 drives the drive unit 41 to adjust the position of the piston 132 so as to maintain an appropriate clearance between the brake disc 124 and the brake pad 133. The braking force generation control unit 202 drives the drive unit 41 to generate a braking force in the brake caliper 42 to stop or decelerate the vehicle. More specifically, the braking force generation control unit 202 causes the drive unit 187 to drive the actuator 92 of the braking pressure generator 63 of the drive unit 41 to generate a braking force in the brake caliper 42 to stop or decelerate the vehicle. The control force generation control unit 203 drives the drive unit 41 to generate braking force in the brake caliper 42 in order to control the vehicle attitude, prevent wheel spin when the vehicle starts or accelerates, or prevent the wheels from locking during braking. The fluid replacement control unit 204 drives the drive unit 41 to replace the brake fluid 82 filled in the brake caliper 42. Alternatively, the fluid replacement control unit 204 drives the drive unit 41 to circulate the brake fluid 82 filled in the drive unit 41, the brake caliper 42, and the hose 43.

[0068] Next, the process of adjusting the gap between the brake disc 124 and the brake pad 133 will be described. The process of adjusting the gap between the brake disc 124 and the brake pad 133 is performed, for example, when starting the vehicle or when the vehicle has finished operating. FIG. 5 is a flowchart illustrating the process of adjusting the gap between the brake disc 124 and the brake pad 133. In step S21, the gap adjustment control unit 201 causes the drive unit 187 to drive the actuator 102 of the brake pressure generator 63 of the drive device 41 to displace the piston 101 of the brake pressure generator 63 to a reference position. Here, the reference position of the piston 101 is the initial position of the piston 101 to be displaced. For example, the reference position of the piston 101 is set to a midpoint of the maximum width of the piston 101's displacement. For example, the reference position of the piston 101 is set to a position where the piston 101 is most retracted toward the actuator 102.

[0069] In step S22, the gap adjustment control unit 201 causes the drive unit 187 to drive the actuator 92 of the braking pressure generator 63 of the drive device 41 to continue displacing the piston 91 of the gap adjuster 62 so as to increase the amount of protrusion of the piston 91 of the gap adjuster 62 toward the storage unit 81. That is, in step S22, the gap adjustment control unit 201 displaces the piston 91 so as to enter the storage unit 81. In other words, in step S22, the piston 91 gradually protrudes toward the storage unit 81.

[0070] In step S23, the gap adjustment control unit 201 acquires, via the input unit 186, a signal from the sensor 134 of the brake caliper 42 that detects the pressure of the brake fluid 82, and detects the pressure of the brake fluid 82.

[0071] In step S24, the gap adjustment control unit 201 refers to the pressure of the brake fluid 82 detected in step S23 and determines whether or not pressure exceeding a predetermined threshold has occurred in the brake fluid 82. If it is determined in step S24 that pressure exceeding the predetermined threshold has not occurred in the brake fluid 82, the procedure returns to step S23, and the above-described procedure is repeated. If it is determined in step S24 that pressure exceeding the predetermined threshold has occurred in the brake fluid 82, the brake pad 133 is pressed in contact with the brake disc 124, so the procedure proceeds to step S25, and the gap adjustment control unit 201 causes the drive unit 187 to drive the actuator 92 of the drive device 41 to stop the displacement of the piston 91 of the gap adjuster 62.

[0072] In step S26, the gap adjustment control unit 201 causes the drive unit 187 to drive the actuator 92 of the braking pressure generator 63 of the drive device 41 to continue displacing the piston 91 of the gap adjuster 62 so as to reduce the amount of protrusion of the piston 91 of the gap adjuster 62 toward the storage unit 81. That is, in step S26, the gap adjustment control unit 201 displaces the piston 91 so as to move out of the storage unit 81. In other words, in step S26, the piston 91 gradually retracts from the storage unit 81.

[0073] In step S27, the gap adjustment control unit 201 acquires, via the input unit 186, a signal from the sensor 134 of the brake caliper 42 that detects the pressure of the brake fluid 82, and detects the pressure of the brake fluid 82.

[0074] In step S28, the gap adjustment control unit 201 refers to the pressure of the brake fluid 82 detected in step S23 and determines whether the pressure of the brake fluid 82 has become zero. If it is determined in step S28 that the pressure of the brake fluid 82 has not become zero, the procedure returns to step S27, and the above-mentioned procedure is repeated. If it is determined in step S28 that the pressure of the brake fluid 82 has become zero, the force with which the brake pads 133 press against the brake discs 124 has become zero, so the procedure proceeds to step S29, and the gap adjustment control unit 201 causes the drive unit 187 to drive the actuator 92 of the braking pressure generator 63 of the drive device 41 to stop the displacement of the piston 91 of the gap adjuster 62.

[0075] In step S30, the gap adjustment control unit 201 causes the drive unit 187 to drive the actuator 92 of the braking pressure generator 63 of the drive device 41, thereby displacing the piston 91 of the gap adjuster 62 so as to reduce the volume of the amount of protrusion of the piston 91 of the gap adjuster 62 toward the storage unit 81 by a predetermined volume, and the process of adjusting the gap between the brake disc 124 and the brake pad 133 is completed.

[0076] In step S30, the gap adjustment control unit 201 causes the drive unit 187 to drive the actuator 92 of the braking pressure generator 63 of the drive device 41, displacing the piston 91 of the gap adjuster 62 so as to reduce the volume of the amount of protrusion of the piston 91 of the gap adjuster 62 toward the storage unit 81 by a predetermined volume, and displacing the piston 132 by a predetermined distance toward the cylinder 141 to a position in the brake caliper 42 where dragging between the brake pad 133 and the brake disc 124 can be avoided.

[0077] The process of adjusting the gap between the brake disc 124 and the brake pad 133 can be performed when a predetermined time has elapsed since the previous gap adjustment process, when a predetermined distance has been traveled, when braking has been performed a predetermined number of times, or in response to a manual command from the vehicle driver.

[0078] In addition, when the braking pressure generator 63 is generating a braking force on the brake caliper 42, the process of adjusting the gap between the brake disc 124 and the brake pad 133 may be performed by having the sensor 134 that detects the position of the piston 132 detect the position of the piston 132, and having the gap adjuster 62 adjust the gap between the brake disc 124 and the brake pad 133 based on the positions of the piston 101 and the piston 132.

[0079] Furthermore, after processing for adjusting the gap between the brake disc 124 and the brake pad 133, the gap adjustment control unit 201 detects the position of the piston 91 of the gap adjuster 62 via the actuator 92 of the braking pressure generator 63 from the drive unit 187, thereby enabling the degree of wear of the brake pad 133 (the thickness of the brake lining of the brake pad 133) to be detected with higher accuracy. This allows for the display of a message urging the replacement of the brake pad 133, for example.

[0080] 6 is a cross-sectional view showing the details of the configuration of a brake system 221, which is another example of an embodiment of the brake system. The brake system 221 is configured to include a drive device 231, a brake caliper 42, and a hose 43. The drive device 231 is configured to include a sealed container 61, a gap adjuster 62, a braking pressure generator 63, and a control pressure generator 241. Of the elements that make up the brake system 221, elements that are similar to the elements that make up the brake system 21 are given the same reference numerals, and descriptions thereof will be omitted.

[0081] The control pressure generator 241 increases or decreases its own volume in response to power or an electrical signal supplied from the ECU 22 via a cable 31, thereby changing the effective volume of the storage section 81 of the sealed container 61, thereby applying pressure to the brake fluid 82 stored in the storage section 81 of the sealed container 61 and sending the brake fluid 82 to the brake caliper 42 or sucking the brake fluid 82 from the brake caliper 42 through the hose 43.

[0082] The control pressure generator 241 is used to control braking force in an antilock brake system, an electronically controlled brake system, a traction control system, or an anti-skid system. In the brake system 221, the amount of brake fluid 82 stored can be reduced, thereby increasing the rigidity of the portion containing the brake fluid 82. This improves the responsiveness of braking force control in the antilock brake system, the electronically controlled brake system, the traction control system, or the anti-skid system, thereby widening the range of braking force control. Furthermore, the brake system 221 can control the braking force for each wheel without being affected by fluctuations in the braking force of other wheels. For example, in the brake system 221, the control pressure generator 241 actively generates pulsations in the brake fluid 82 during braking, detects the vehicle posture and the state of braking force generation, and generates a stronger braking force more safely, enabling the vehicle to decelerate or stop in a shorter distance.

[0083] In this case, the ECU 22 acquires from the brake pedal sensor 23 the amount of brake pedal depression, the force with which the brake pedal is depressed, the acceleration of the brake pedal being depressed, etc., and from the sensor 24 the vehicle speed, the outside temperature of the vehicle, the atmospheric pressure, weather such as whether it is raining, the inclination of the vehicle, the gradient of the road on which the vehicle is located, the steering angle, the road surface conditions, the vehicle acceleration (six-axis acceleration), and the rotation speed of each wheel, and by referring to this information, causes the control pressure generator 241 to control the braking force. Furthermore, the ECU 22 acquires and stores the characteristics and habits of the driver who is driving the vehicle (for example, how to depress the brake pedal when stopping or how to depress the brake pedal while steering), and by referring to this information, causes the control pressure generator 241 to control the braking force. That is, the control force generation control unit 203 causes the drive unit 187 to drive the actuator 262 (described later) of the control pressure generator 241 of the drive device 231 to generate a braking force in the brake caliper 42 in order to control the vehicle attitude, to prevent the wheels from spinning when the vehicle starts or accelerates, or to prevent the wheels from locking when braking.

[0084] The control pressure generator 241 includes a piston 261, an actuator 262, and a frame 263. The piston 261 enters and leaves the storage section 81 of the sealed container 61. The piston 261 is formed of a material with high rigidity and strength, such as metal, resin, or a composite material. For example, the piston 261 is formed into a cylindrical shape from a steel material. For example, the piston 261 is formed into a cylindrical shape from a steel material, with the storage section 81 side being hemispherical. The shape of the piston 261 can be any desired shape, such as a prismatic shape, a pyramidal shape, a spherical shape, a hemispherical shape, or an oblong shape.

[0085] The volume of the piston 261 is smaller than the volume of the piston 101. Furthermore, the cross-sectional area of ​​the piston 261, which is perpendicular to the direction of displacement when the piston 261 moves in and out of the storage section 81, is smaller than the cross-sectional area of ​​the piston 101, which is perpendicular to the direction of displacement when the piston 101 moves in and out of the storage section 81. In this case, for example, the cross-sectional area refers to the maximum cross-sectional area. Furthermore, for example, the cross-sectional area refers to the cross-sectional area at a position where the piston 261 or the piston 101 protrudes from the frame 103 or the frame 263 by a predetermined length (for example, a reference position for each operation).

[0086] By doing so, the weight of the piston 261 can be made smaller, which improves the response of the control and enables the pressure applied to the brake fluid 82 to be changed more quickly.

[0087] The actuator 262 electrically drives the piston 261 to move in and out of the storage section 81 of the sealed container 61. In other words, the actuator 262 displaces the piston 261 to move in and out of the storage section 81 of the sealed container 61. For example, the actuator 262 is a linear actuator. That is, the actuator 262 linearly displaces the piston 261 to move in and out of the storage section 81. For example, the actuator 262 is made up of an electric motor (motor) and a ball screw, and drives the piston 261. Alternatively, for example, the actuator 262 is made up of an electric motor (motor) and a rack and pinion, and drives the piston 261.

[0088] The frame 263 supports the piston 261 and the actuator 262. The frame 263 is made of a highly rigid and strong material such as metal, resin, or composite material.

[0089] The control pressure generator 241 is disposed in the storage section 81 of the sealed container 61 so as not to interfere with both the gap adjuster 62 and the braking pressure generator 63. That is, the gap adjuster 62, the braking pressure generator 63, and the control pressure generator 241 each independently move the piston 91, the piston 101, and the piston 261 in and out of the storage section 81 of the sealed container 61.

[0090] Furthermore, although the actuator 262 has been described as consisting of an electric motor and a ball screw or an electric motor and a rack and pinion, it is not limited to this and mechanisms that perform electromechanical operations, such as a solenoid, a cam mechanism, or a yoke mechanism, can also be used.

[0091] 7 is a cross-sectional view showing the details of the configuration of a brake system 301, which is yet another example of an embodiment of the brake system. The brake system 301 is configured to include a drive unit 311, a brake caliper 312, and hoses 322 and 323. Of the elements constituting the brake system 301, elements that are similar to the elements constituting the brake system 21 are assigned the same reference numerals, and description thereof will be omitted.

[0092] The drive device 311 is configured to include a sealed container 61, a gap adjuster 62, and a braking pressure generator 321. The sealed container 61 hermetically contains the brake fluid 82, except for the connected hoses 322 and 323. In other words, the brake fluid 82 contained in the sealed container 61 flows in and out of the sealed container 61 only from the hose 322 or 323.

[0093] The hose 322 and the hose 323 connect the brake caliper 312 and the drive unit 311, respectively, through the brake fluid 82 so as to transmit the pressure of the brake fluid 82.

[0094] One end of the hose 322 is connected to the sealed container 61 of the drive unit 311, and the other end of the hose 322 is connected to a cylinder 371 formed in the cylinder body 131. For example, one end of the hose 322 is connected near a piston 341 (described later) of the braking pressure generator 321. A valve 361 is provided at one end of the hose 322. The valve 361 is a so-called check valve (a check valve). The valve 361 stops the brake fluid 82 from flowing from the hose 322 into the storage portion 81 of the sealed container 61. The brake fluid 82 can flow from the storage portion 81 of the sealed container 61 to the hose 322 through the valve 361.

[0095] One end of the hose 323 is connected to the sealed container 61 of the drive unit 311, and the other end of the hose 323 is connected to a cylinder 371 formed in the cylinder body 131. For example, one end of the hose 323 is connected near the piston 91 of the gap adjuster 62. A valve 362 is provided at one end of the hose 323. The valve 362 is a so-called check valve. The valve 362 stops the brake fluid 82 from flowing from the storage section 81 of the sealed container 61 into the hose 323. The brake fluid 82 can flow from the hose 323 into the storage section 81 of the sealed container 61 through the valve 362.

[0096] The brake pressure generator 321 increases or decreases its own volume in response to power or an electrical signal supplied from the ECU 22 via the cable 31, thereby changing the effective volume of the storage section 81 of the sealed container 61, thereby applying pressure to the brake fluid 82 stored in the storage section 81 of the sealed container 61 and sending the brake fluid 82 from the storage section 81 to the brake caliper 42 through the hose 322, or sucking the brake fluid 82 from the brake caliper 42 into the storage section 81 through the hose 323.

[0097] The braking pressure generator 321 includes a piston 341, an actuator 342, and a frame 343. The piston 341 enters and leaves the storage section 81 of the sealed container 61. The piston 341 is formed of a highly rigid and strong material such as metal, resin, or a composite material. For example, the piston 341 is formed into a cylindrical shape from steel. For example, the piston 341 is formed into a cylindrical shape from steel, with the storage section 81 side being hemispherical. The shape of the piston 341 can be any desired shape, such as a prismatic shape, a pyramidal shape, a spherical shape, a hemispherical shape, or an oblong shape.

[0098] The volume of piston 341 is smaller than the volume of piston 91. In addition, the cross-sectional area of ​​piston 341, which is perpendicular to the direction of displacement when piston 341 moves in and out of storage section 81, is smaller than the cross-sectional area of ​​piston 91, which is perpendicular to the direction of displacement when piston 91 moves in and out of storage section 81.

[0099] The actuator 342 electrically drives the piston 341 to move in and out of the storage section 81 of the sealed container 61. In other words, the actuator 342 displaces the piston 341 to move in and out of the storage section 81 of the sealed container 61. For example, the actuator 342 is a linear actuator. That is, the actuator 342 linearly displaces the piston 341 to move in and out of the storage section 81. For example, the actuator 342 is made up of an electric motor and a ball screw and drives the piston 341. Alternatively, for example, the actuator 342 is made up of an electric motor and a rack and pinion and drives the piston 341.

[0100] The frame 343 supports the piston 341 and the actuator 342. The frame 343 is made of a highly rigid and strong material such as metal, resin, or composite material.

[0101] A partition 351 is also provided to be connected to the frame 343. The partition 351 separates the brake fluid 82 flowing out from the valve 362 to the storage section 81 from the brake fluid 82 flowing from the storage section 81 to the valve 361. The partition 351 separates the inside of the storage section 81 so that the brake fluid 82 flowing out from the valve 362 to the storage section 81 and the brake fluid 82 flowing from the storage section 81 to the valve 361 circulate within the storage section 81.

[0102] The braking pressure generator 321 is disposed in the storage section 81 of the sealed container 61 so as not to interfere with the gap adjuster 62. That is, the gap adjuster 62 and the braking pressure generator 321 independently move the piston 91 and the piston 341 in and out of the storage section 81 of the sealed container 61, respectively.

[0103] A cylinder 371 is formed in the cylinder body 131. The cylinder 371 is formed in a cylindrical shape with an inner diameter corresponding to the outer diameter of the piston 132. Because the inner diameter of the cylinder 371 corresponds to the outer diameter of the piston 132, the brake fluid 82 does not leak even when pressure is applied to the brake fluid 82.

[0104] A partition 372 is provided inside the cylinder 371. The partition 371 separates the brake fluid 82 flowing into the cylinder 371 from the hose 322 and the brake fluid 82 flowing out from the cylinder 371 to the hose 323. The partition 371 separates the inside of the cylinder 371 so that the brake fluid 82 flowing into the cylinder 371 from the hose 322 and the brake fluid 82 flowing out from the cylinder 371 to the hose 323 circulate inside the cylinder 371.

[0105] Next, the process of replacing the brake fluid 82 in the cylinder 371 in the brake system 301 will be described. The process of replacing the brake fluid 82 in the cylinder 371 is performed, for example, when the vehicle is started or when the vehicle is finished operating. FIG. 8 is a flowchart illustrating the process of replacing the brake fluid 82. In step S41, the fluid replacement control unit 204 causes the drive unit 187 to drive the actuator 342 of the brake pressure generator 321 of the drive device 311 to retract the piston 341 of the brake pressure generator 321 to the maximum extent. As a result, the piston 341 is retracted toward the frame 343, and the volume of the storage unit 81 becomes larger.

[0106] In step S42, the fluid replacement control unit 204 acquires data indicating the position of the piston 91 from the drive unit 187, which drives the actuator 92 of the drive device 311, and stores the position of the piston 91 of the gap adjuster 62 in the memory unit 188.

[0107] In step S43, the fluid replacement control unit 204 causes the drive unit 187 to drive the actuator 92 of the gap adjuster 62 of the drive device 311 to retract the piston 91 of the gap adjuster 62 toward the frame 93 so as to increase the internal volume of the storage unit 81 by a predetermined volume. As a result, the piston 91 is retracted toward the frame 93, and the volume of the storage unit 81 becomes larger, so that the brake fluid 82 is sucked into the storage unit 81 from the cylinder 371 through the hose 323. In this case, a valve 361 is provided at one end of the hose 322, which prevents the brake fluid 82 from flowing out from the hose 322 into the storage section 81 of the sealed container 61. Also, a valve 362 is provided at one end of the hose 323, and the brake fluid 82 can flow from the hose 323 into the storage section 81 of the sealed container 61 through the valve 362, so that the brake fluid 82 is sucked into the storage section 81 from the cylinder 371 only through the hose 323.

[0108] In step S44, the fluid replacement control unit 204 causes the drive unit 187 to drive the actuator 92 of the gap adjuster 62 of the drive device 311, causing the piston 91 of the gap adjuster 62 to protrude toward the storage unit 81 so as to reduce the internal volume of the storage unit 81 by a predetermined volume. As a result, the piston 91 protrudes from the frame 93, and the volume of the storage unit 81 becomes smaller, so that the brake fluid 82 is sent from the storage unit 81 through the hose 322 to the cylinder 371. In this case, a valve 362 is provided at one end of the hose 323, and the valve 362 stops the flow of brake fluid 82 from inside the storage section 81 of the sealed container 61 into the hose 323. Also, a valve 361 is provided at one end of the hose 322, and the brake fluid 82 can flow from inside the storage section 81 of the sealed container 61 into the hose 322 through the valve 361, so that the brake fluid 82 is sent from the storage section 81 to the cylinder 371 only through the hose 322.

[0109] A partition 351 is provided to be connected to the frame 343, and the partition 351 separates the brake fluid 82 flowing out from the valve 362 to the storage section 81 from the brake fluid 82 flowing from the storage section 81 to the valve 361, so that the brake fluid 82 circulates in a predetermined direction within the storage section 81.

[0110] Furthermore, a partition 372 is provided within the cylinder 371, and the partition 371 separates the brake fluid 82 flowing into the cylinder 371 from the hose 322 and the brake fluid 82 flowing out from the cylinder 371 to the hose 323, so that the brake fluid 82 circulates within the cylinder 371 in a predetermined direction.

[0111] As a result, the brake fluid 82 in the cylinder 371 is replaced.

[0112] In step S45, the fluid replacement control unit 204 determines whether the displacement of the piston 91 of the gap adjuster 62 in steps S43 and S44 has been repeated a predetermined number of times. If it is determined in step S45 that the displacement of the piston 91 of the gap adjuster 62 has not been repeated the predetermined number of times, the procedure returns to step S43, and the displacement of the piston 91 of the gap adjuster 62 is repeated.

[0113] If it is determined in step S45 that the displacement of the piston 91 of the gap adjuster 62 has been repeated a predetermined number of times, the procedure proceeds to step S46, where the fluid replacement control unit 204 reads the position of the piston 91 of the gap adjuster 62 from the memory unit 188 and causes the drive unit 187 to drive the actuator 92 of the gap adjuster 62 of the drive device 311 to return the piston 91 of the gap adjuster 62 to the stored position.

[0114] In step S47, the fluid replacement control unit 204 causes the drive unit 187 to drive the actuator 342 of the brake pressure generator 321 of the drive device 311, thereby displacing the piston 341 of the brake pressure generator 321 to the reference position, and the process of replacing the brake fluid 82 is completed.

[0115] In conventional disc brakes, brake fluid is replenished from a reservoir to compensate for the increase in the amount of brake fluid in the brake caliper as the brake pads wear. However, the brake fluid in the brake caliper is not replaced or circulated, but remains there until it is replaced periodically as specified in the scheduled maintenance instructions. During this time, the brake fluid deteriorates due to thermal stress at relative temperatures exceeding 300°C, and further deterioration is accelerated physically and chemically by oxygen and moisture in the air.

[0116] In brake system 21, brake system 221, or brake system 301, brake fluid 82 is completely isolated from the outside and is not mixed with outside air, preventing deterioration due to chemical reactions such as oxidation. On the other hand, with regard to deterioration due to thermal stress, recent technological advances in brake fluids (for example, improvements in the heat resistance of DOT6, etc.) have somewhat extended the replacement interval, but this does not mean that the system can be called maintenance-free.

[0117] Therefore, in the brake system 301, the brake fluid 82 in the cylinder 371 is replaced to distribute the deterioration due to thermal stress throughout the brake fluid 82 in the brake system 301, preventing localized deterioration. This makes it possible to extend the life of the brake fluid 82 while maintaining its functionality. By circulating the brake fluid 82 within the closed brake system 301, maintenance is no longer required almost indefinitely (20 years or 200,000 km longer than the normal vehicle lifespan), achieving a maintenance-free system.

[0118] The process of replacing the brake fluid 82 in the cylinder 371 can be performed when a predetermined time has passed since the previous replacement process, when a predetermined distance has been driven, when the brakes have been applied a predetermined number of times, or in response to a manual command from the vehicle driver.

[0119] 9 is a cross-sectional view showing the details of the configuration of a brake system 401, which is yet another example of an embodiment of the brake system. The brake system 401 is configured to include a drive unit 421, a brake caliper 42, and a hose 422. Of the elements constituting the brake system 401, elements that are similar to the elements constituting the brake system 221 are assigned the same reference numerals, and description thereof will be omitted.

[0120] The drive device 421 is configured to include a sealed container 61, a gap adjuster 62, a braking pressure generator 63, and a control pressure generator 241. The sealed container 61 hermetically contains the brake fluid 82 except for the hose 422 connected thereto. That is, the brake fluid 82 contained in the sealed container 61 flows in and out of the sealed container 61 only through the hose 422.

[0121] A hose 422 connects the brake caliper 312 and the drive unit 421 through the brake fluid 82 to transmit the pressure of the brake fluid 82 .

[0122] One end of the hose 422 is connected to the sealed container 61 of the drive unit 421, and the other end of the hose 422 is connected to the cylinder 141 formed in the cylinder body 131. Valves 431 and 432 are provided at one end of the hose 422. The valves 431 and 432 are each a so-called check valve. The valves 431 and 432 are arranged in contact with and opposite to the partition 441.

[0123] The valve 431 stops the brake fluid 82 from flowing out of the hose 422 into the storage section 81 of the sealed container 61. The brake fluid 82 can flow from the storage section 81 of the sealed container 61 to the hose 422 through the valve 431.

[0124] The valve 432 prevents the brake fluid 82 from flowing from the storage section 81 of the sealed container 61 into the hose 422. The brake fluid 82 can flow from the hose 422 into the storage section 81 of the sealed container 61 through the valve 432.

[0125] The partition 441 separates the brake fluid 82 flowing out from the valve 432 to the storage section 81 from the brake fluid 82 flowing from the storage section 81 into the valve 431. The partition 441 separates the inside of the storage section 81 so that the brake fluid 82 flowing out from the valve 432 to the storage section 81 and the brake fluid 82 flowing from the storage section 81 to the valve 431 circulate within the storage section 81.

[0126] The process of replacing the brake fluid 82 in the cylinder 141 in the brake system 401 is the same as the process described with reference to the flowchart of FIG. 8, and therefore a description thereof will be omitted.

[0127] 10 is a cross-sectional view showing the details of the configuration of a brake system 501, which is yet another example of an embodiment of the brake system. The brake system 501 is configured to include a drive unit 511, a brake caliper 42, and a hose 422. Of the elements constituting the brake system 501, elements that are similar to the elements constituting the brake system 401 are assigned the same reference numerals, and description thereof will be omitted.

[0128] The drive device 511 drives the brake caliper 42 under the control and drive of the ECU 22. The drive device 511 applies pressure to the brake fluid 82 to send the brake fluid 82 to the brake caliper 42 or sucks the brake fluid 82 from the brake caliper 42.

[0129] The drive device 511 is configured to include a sealed container 61 and a gap adjustment brake pressure generator 522. The gap adjustment brake pressure generator 522 increases or decreases its own volume in response to power or an electric signal supplied from the ECU 22 via the cable 31, thereby changing the effective volume of the storage section 81 of the sealed container 61, thereby applying pressure to the brake fluid 82 stored in the storage section 81 of the sealed container 61 and sending the brake fluid 82 to the brake caliper 42 or sucking the brake fluid 82 from the brake caliper 42 through the hose 422.

[0130] The gap adjustment braking pressure generator 522 includes a piston 531, an actuator 532, a piston 533, an actuator 534, and a frame 535. The piston 531 moves in and out of the storage section 81 of the sealed container 61. The piston 531 is made of a material with high rigidity and strength, such as metal, resin, or a composite material. For example, the piston 531 is made of steel and has a cylindrical shape.

[0131] Piston 531 also incorporates piston 533 and actuator 534. Piston 533 and actuator 534 are stored in a hole formed in a portion of piston 531 on the storage section 81 side. Piston 531 stores piston 533 in a displaceable manner. Piston 531 supports piston 533 and actuator 534.

[0132] For example, the piston 531 may be made of steel and formed into a cylindrical shape with a hemispherical side facing the storage section 81. The shape of the piston 531 may be any desired shape, such as a prismatic shape, a pyramidal shape, a spherical shape, a hemispherical shape, or an oblong shape.

[0133] The actuator 532 electrically drives the piston 531 to move in and out of the storage section 81 of the sealed container 61 using power or an electric signal supplied from the ECU 22 via the cable 31. In other words, the actuator 532 displaces the piston 531 to move in and out of the storage section 81 of the sealed container 61. For example, the actuator 532 is a linear actuator. That is, the actuator 532 linearly displaces the piston 531 to move in and out of the storage section 81. For example, the actuator 532 is made up of an electric motor (motor) and a ball screw and drives the piston 531. Alternatively, for example, the actuator 532 is made up of an electric motor (motor) and a rack and pinion and drives the piston 531.

[0134] The piston 533 enters and leaves the storage section 81 of the sealed container 61. The piston 533 enters and leaves the storage section 81 through a hole formed in the piston 531. The piston 533 is formed of a material with high rigidity and strength, such as metal, resin, or a composite material. For example, the piston 533 is formed into a cylindrical shape from a steel material. For example, the piston 533 is formed into a cylindrical shape from a steel material, with the storage section 81 side being hemispherical. The shape of the piston 533 can be any desired shape, such as a prismatic shape, a pyramidal shape, a spherical shape, a hemispherical shape, or an oblong shape.

[0135] The volume of piston 533 is smaller than the volume of piston 531. In addition, the cross-sectional area of ​​piston 533, which is perpendicular to the direction of displacement when piston 533 moves in and out of storage section 81, is smaller than the cross-sectional area of ​​piston 531, which is perpendicular to the direction of displacement when piston 531 moves in and out of storage section 81.

[0136] For example, when piston 531 and piston 533 are each formed in a cylindrical shape, the radius of the circular bottom surface of piston 533 is set to be less than half the radius of the circular bottom surface of piston 531.

[0137] The actuator 534 is fixed to a hole formed in the piston 531. The actuator 534 electrically drives the piston 533 to move in and out of the storage section 81 of the sealed container 61. In other words, the actuator 534 displaces the piston 533 from the hole formed in the piston 531 to move in and out of the storage section 81 of the sealed container 61. For example, the actuator 534 is a linear actuator. That is, the actuator 534 linearly displaces the piston 533 to move in and out of the storage section 81. For example, the actuator 534 is made up of an electric motor (motor) and a ball screw and drives the piston 533. Alternatively, for example, the actuator 534 is made up of an electric motor (motor) and a rack and pinion and drives the piston 533.

[0138] The frame 535 supports the piston 531 and the actuator 532. The frame 535 is made of a highly rigid and strong material such as metal, resin, or composite material.

[0139] Instead of piston 91, piston 101, piston 261, piston 341, piston 531 or piston 533, a rotor having a fan-shaped columnar bottom or a cylindrical cam having an eccentric shaft may be electrically rotated by actuator 92, actuator 102, actuator 262, actuator 342, actuator 532 or actuator 534, causing the rotor or cam to move in and out of storage section 81 and changing the internal volume of storage section 81. Also, instead of piston 91, piston 101, piston 261, piston 341, piston 531 or piston 533, a plunger may be provided.

[0140] Furthermore, although the valves 361, 362, 431, and 432 have been described as check valves, they may be electromagnetic on-off valves. In this case, the valves 361, 362, 431, and 432 are opened and closed as appropriate under the control of the ECU 22 in accordance with the operating state or timing, such as when generating braking force or when ending the generation of braking force.

[0141] Note that a sensor for detecting the position of piston 91, piston 101, piston 261, piston 341, piston 531, or piston 533, a sensor for detecting the pressure of brake fluid 82, or a sensor for detecting the temperature of brake fluid 82 may be provided in drive unit 41, drive unit 231, drive unit 311, drive unit 421, or drive unit 511. In this case, a signal from the sensor provided in drive unit 41, drive unit 231, drive unit 311, drive unit 421, or drive unit 511 is supplied to ECU 22 via cable 31.

[0142] According to the brake system 21, the brake system 221, the brake system 301, the brake system 401 or the brake system 501, when the brake pad 133 is worn, the brake pad 133 can be replaced easily, quickly and reliably.

[0143] The ECU 22 executes the maintenance and inspection program, causing the drive unit 187 to drive the gap adjuster 62 or the gap adjustment brake pressure generator 522 to retract the piston 91 toward the frame 93 or the piston 531 toward the frame 535 so as to increase the internal volume of the storage unit 81 to its maximum. As a result, the brake fluid 82 is sucked into the storage unit 81 from the cylinder 141 or the cylinder 371 through the hose 323, and the piston 132 is drawn into the cylinder 141 or the cylinder 371. This allows a gap to be generated between the brake pads 133 and the piston 132, making it possible to easily remove the brake pads 133 from the brake caliper 42 or the brake caliper 312 and to insert new or cleaned brake pads 133 into the brake caliper 42 or the brake caliper 312.

[0144] After inserting new brake pads 133 or cleaned brake pads 133 into the brake caliper 42 or brake caliper 312, the replacement or cleaning of the brake pads 133 is completed by performing the process of adjusting the gap between the brake disc 124 and the brake pads 133, as described with reference to the flowchart of Figure 5.

[0145] In this way, the brake system 21 is configured to include one drive unit 41, one brake caliper 42, and one hose 43. Alternatively, the brake system 301 is configured to include one drive unit 311, one brake caliper 312, and the hoses 322 and 323.

[0146] The brake caliper 42 in the brake system 21 is a brake caliper 42 for a disc brake 124, and presses the brake pads 133 against the brake disc 124 with brake fluid 82 filled therein. The drive unit 41 applies pressure to the brake fluid 82 to send the brake fluid 82 to the brake caliper 42 or to suck the brake fluid 82 from the brake caliper 42. The hose 43 connects the brake caliper 42 and the drive unit 41 through the brake fluid 82 to transmit the pressure of the brake fluid 82. The hose 322 and the hose 323 connect the brake caliper 312 and the drive unit 311 through the brake fluid 82 to transmit the pressure of the brake fluid 82.

[0147] The drive device 41 is provided with a sealed container 61 in which a hollow storage section 81 of a predetermined internal volume is formed and filled with brake fluid 82, a piston 91 that moves in and out of the storage section 81 to change the internal volume of the storage section 81, and an actuator 92 that electrically drives the piston 91 to move in and out of the storage section 81. The brake fluid 82 is sealed by the drive device 41, the brake caliper 42, and the hose 43, and is isolated from the outside.

[0148] The driving device 41 may further include a piston 101 that moves in and out of the storage section 81 to change the internal volume of the storage section 81, and an actuator 102 that electrically drives the piston 101 to move in and out of the storage section 81. The cross-sectional area of ​​the piston 101, which is perpendicular to the direction of displacement when the piston 101 moves in and out of the storage section 81, is smaller than the cross-sectional area of ​​the piston 91, which is perpendicular to the direction of displacement when the piston 91 moves in and out of the storage section 81.

[0149] The piston 91 and actuator 92 can be used to adjust the gap between the brake pad 133 and the brake disc 124 .

[0150] The piston 101 and actuator 102 can be used for braking.

[0151] Piston 531 may house piston 533 and actuator 534 .

[0152] The drive device 41 can further be provided with a piston 261 that moves in and out of the storage section 81 to change the internal volume of the storage section 81, and an actuator 262 that electrically drives the piston 261 to move in and out of the storage section 81, and the cross-sectional area of ​​the piston 261, which is the cross-sectional area of ​​the cross section perpendicular to the direction of displacement when the piston 261 moves in and out of the storage section 81, is smaller than the cross-sectional area of ​​the piston 101, which is the cross-sectional area of ​​the cross section perpendicular to the direction of displacement when the piston 101 moves in and out of the storage section 81.

[0153] The piston 261 and actuator 262 can be used to control braking force in an anti-lock braking system, an electronically controlled braking system, a traction control system, or an electronic stability control system.

[0154] The drive unit 41 can further be provided with a valve 432 at the end of the hose 422 on the drive unit 421 side to stop the flow of brake fluid 82 from the storage unit 81 into the hose 422, and a valve 431 to stop the flow of brake fluid 82 from the hose 422 to the storage unit 81.

[0155] The storage section 81 of the drive device 41 may further be provided with a partition 441 that separates the brake fluid 82 flowing from the valve 432 into the storage section 81 from the brake fluid 82 flowing from the storage section 81 into the valve 431 .

[0156] A valve 362 for stopping the flow of brake fluid 82 from the storage section 81 into the hose 323 can be further provided at the end of the hose 323 on the drive device 311 side, and a valve 361 for stopping the flow of brake fluid 82 from the hose 322 into the storage section 81 can be further provided at the end of the hose 322 on the drive device 311 side.

[0157] Furthermore, the embodiments of the present invention are not limited to the above-described embodiments, and various modifications are possible within the scope of the gist of the present invention.

[0158] 11 Vehicle brake system, 21 and 21-1 to 21-4, 221, 301, 401 and 501 Brake system, 22 ECU, 23 Brake pedal sensor, 24 Sensor, 31 and 31-1 to 31-4 and 32 and 32-1 to 32-4 Cable, 41 and 41-1 to 41-4, 231, 311, 421 and 511 Drive device, 42 and 42-1 to 42-4 and 312 Brake caliper, 43 and 43-1 to 43-4, 322 and 323 and 422 Hose, 61 Sealed container, 62 Gap adjuster, 63 and 321 Brake pressure generator, 81 Storage section, 82 Brake fluid, 91, 101, 261, 341, 531 and 533 Piston, 92, 102, 262, 342, 532 and 534 Actuator, 93, 103, 263, 343, 535 Frame, 122 Mounting bracket, 123 Slide pin, 124 Brake disc, 125 Hub, 126 Wheel, 131 Cylinder body, 132 Piston, 133 Brake pad, Sensor, 141 and 371 Cylinder, 181 CPU, 182 ROM, 183 RAM, 184 Bus, 185 Input / output interface, 186 Input unit, 187 Drive unit, 188 Memory unit, 189 Communication unit, 201 Gap adjustment control unit, 202 Braking force generation control unit, 203 Control force generation control unit, 204 Fluid replacement control unit, 241 Control pressure generator 351, 372 and 441 partitions, 361, 362, 431 and 432 valves, 522 gap adjustment brake pressure generator

Claims

1. A brake system including a brake caliper for disc brakes, the brake caliper pressing brake pads against a brake disc by brake fluid filled therein, a drive unit applying pressure to the brake fluid to send the brake fluid to the brake caliper or to suck the brake fluid from the brake caliper, and one or more hoses connecting the brake caliper and the drive unit through the brake fluid to transmit the pressure of the brake fluid, the drive unit being provided with: a container in which a hollow storage section of a predetermined internal volume in which the brake fluid is filled is formed; first internal volume changing means for changing the internal volume of the storage section by entering and exiting the storage section; first drive means for electrically driving the first internal volume changing means so as to enter and exit the storage section; second internal volume changing means for changing the internal volume of the storage section by entering and exiting the storage section; and second drive means for electrically driving the second internal volume changing means so as to enter and exit the storage section, a cross-sectional area of ​​the second volume changing means, which is a cross-sectional area perpendicular to the direction of displacement when the second volume changing means enters and leaves the storage section, is smaller than a cross-sectional area of ​​the first volume changing means, which is a cross-sectional area perpendicular to the direction of displacement when the first volume changing means enters and leaves the storage section, and the brake fluid is sealed by the drive unit, the brake caliper and the hose and isolated from the outside.

2. A brake system according to claim 1, wherein the first internal volume changing means and the first driving means are used to adjust the gap between the brake pad and the brake disc.

3. A brake system according to claim 1, wherein the second internal volume changing means and the second driving means are used for braking.

4. A brake system according to claim 1, wherein the first internal volume changing means incorporates the second internal volume changing means and the second drive means.

5. A brake system as described in claim 1, wherein the drive device is further provided with a third volume change means which moves in and out of the storage section to change the volume of the storage section, and a third drive means which electrically drives the third volume change means so that the third volume change means moves in and out of the storage section, and the cross-sectional area of ​​the third volume change means which is perpendicular to the direction of displacement when the third volume change means moves in and out of the storage section is smaller than the cross-sectional area of ​​the second volume change means which is perpendicular to the direction of displacement when the second volume change means moves in and out of the storage section.

6. A brake system according to claim 5, wherein the third internal volume changing means and the third driving means are used to control the braking force in an anti-lock brake system, an electronically controlled brake system, a traction control system or an anti-skid device.

7. A brake system as claimed in claim 1, wherein the drive device is further provided with a first valve at the end of the hose on the drive device side for stopping the inflow of the brake fluid from the storage section into the hose, and a second valve for stopping the outflow of the brake fluid from the hose to the storage section.

8. A brake system as described in claim 7, wherein the storage section of the drive device is further provided with a partition that separates the brake fluid flowing out from the first valve to the storage section from the brake fluid flowing from the storage section to the second valve.

9. A brake system as described in claim 1, wherein the number of hoses is two, and the drive device is further provided with a first valve at an end of one of the two hoses that is on the drive device side, for stopping the inflow of the brake fluid from the storage section into one of the hoses, and a second valve at an end of the other of the two hoses that is on the drive device side, for stopping the outflow of the brake fluid from the other hose to the storage section.

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