Brake control device

Abstract

The invention provides a brake control device capable of ensuring waterproofness of a sensor side and arranging a magnet and a sensor closer to each other. The opening of the shaft housing hole is sealed by the film of the sealing member.

Description

Technical Field

[0001] This invention relates to a braking control device. Background Technology

[0002] Patent Document 1 discloses a brake control device that uses a pump driven by an electric motor to control brake hydraulic pressure. A magnet mounted on the front end of the motor shaft and a magnetic flux detection sensor mounted on a control board are positioned opposite each other via a sealing member. The sensor detects the rotational position of the motor. The sealing member prevents brake fluid from seeping in from the housing side to the sensor side, blocking the opening on the sensor side of the shaft receiving hole in the housing.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent No. 6898888 Summary of the Invention

[0006] The technical problem that the invention aims to solve

[0007] However, in the aforementioned patent document 1, since a resin-made sealing component is used, the required thickness in the molding must be ensured, and the distance between the magnet and the sensor becomes farther, which leads to a problem of reduced magnetic flux detection accuracy of the sensor.

[0008] One of the objectives of this invention is to provide a braking control device that can place the magnet and the sensor closer together while ensuring the waterproofness of the sensor side.

[0009] Technical solutions for solving technical problems

[0010] A braking control device according to one embodiment of the present invention includes a sealing member, which is installed in the opening of the shaft receiving hole on the second side of the housing and has a thin film for sealing the opening.

[0011] Therefore, in one embodiment of the present invention, the waterproofness of the sensor side can be ensured, and the magnet and the sensor can be configured closer together. Attached Figure Description

[0012] Figure 1 This is a longitudinal cross-sectional view of the braking control device 1 according to Embodiment 1.

[0013] Figure 2 yes Figure 1 Enlarged view of the main parts.

[0014] Figure 3 This is a perspective view of the shaft storage hole 2d as seen from the back 22 side of the outer casing 2.

[0015] Figure 4 (a) is an exploded perspective view of the sealing component 10 of Embodiment 1. Figure 4 (b) is a cross-sectional perspective view of the sealing component 10 of Embodiment 1.

[0016] Figure 5 (a) is an exploded perspective view of the sealing component 10 of Embodiment 2. Figure 5 (b) is a cross-sectional perspective view of the sealing component 10 of Embodiment 2. Detailed Implementation

[0017] [Implementation Method 1]

[0018] Figure 1 This is a longitudinal cross-sectional view of the braking control device 1 according to Embodiment 1.

[0019] Braking control device 1 is applied, for example, to electric vehicles. Electric vehicles include hybrid vehicles, where the prime mover for driving the wheels is an engine and an electric generator, and electric vehicles, where the prime mover is only an electric generator. In electric vehicles, regenerative braking, which converts the vehicle's kinetic energy into electrical energy through electricity generation, can be performed to brake the vehicle. Braking control device 1 converts the vehicle's kinetic energy into heat energy through friction, thereby generating braking force. Braking actuation units are installed on each wheel. These braking actuation units are, for example, disc brakes with hydraulic calipers.

[0020] The brake caliper has a brake disc and brake pads. The brake disc is a brake rotor that rotates integrally with the tire. The brake pads are positioned relative to the brake disc with a specified gap and are moved by hydraulic pressure from the wheel cylinders. Braking force is generated by pressing the brake pads against the brake disc and utilizing their friction. The brake control device 1 has brake piping for both a main system and a sub-system. The brake piping type is, for example, an X-pipe type. Alternatively, other piping types such as front and rear piping can also be used. The brake control device 1 is positioned between the master cylinder and each brake actuation unit, supplies brake fluid to each brake actuation unit, and controls the brake hydraulic pressure of the wheel cylinders.

[0021] The brake control unit 1 is located in an electric motor compartment isolated from the vehicle's driver's cab. The brake control unit 1 includes a housing 2, an electric motor 3, a travel simulator (not shown), and a control unit 5. The housing 2 is fixed to the floor of the electric motor compartment via shock absorbers and brackets (not shown). The brackets are secured to the floor with multiple screws. The housing 2 is a frame that houses a pump 6, multiple solenoid valves 7, and multiple hydraulic sensors 8. The housing 2 is a generally rectangular block made of aluminum alloy. Inside the housing 2, there is a dual-system circuit for the flow of brake fluid, consisting of a main system and a secondary system. The dual-system circuit comprises multiple fluid lines.

[0022] The electric motor 3 is a brushless electric motor, comprising a motor housing 31, a stator 32, a rotor shaft 33, a rotor 34, and a power connector 35. The motor housing 31 is formed as a bottomed cylinder with a cylindrical portion 31a and two bottoms 31b and 31c. The bottom 31c has a central opening. The motor housing 31 is fastened to the front (first surface) 21 of the outer casing 2 using screws (not shown). The stator 32 is fixed to the inner circumferential surface of the cylindrical portion 31a. The rotor shaft 33 is formed as a cylinder and mounted on the motor housing 31 in a manner that allows it to rotate about the rotation axis O1. Hereinafter, the X-axis is defined as the direction in which the rotation axis O1 extends, and the direction from the bottom 31b side towards the bottom 31c side is defined as the positive X-axis direction. Furthermore, the radial direction of the rotation axis O1 is defined as radial, and the direction about the rotation axis O1 is defined as circumferential.

[0023] The negative X-axis end of the rotor shaft 33 is supported by a bearing 37a mounted on the bottom 31b, allowing it to rotate relative to the motor housing 31. The positive X-axis end of the rotor shaft 33 is supported by a bearing 37b mounted on the bottom 31c, allowing it to rotate relative to the motor housing 31. The positive X-axis end of the rotor shaft 33 protrudes further into the positive X-axis direction than the bottom 31c. The rotor 34 is fixed to the outer periphery of the rotor shaft 33 and is radially opposite to the stator 32. The rotor 34 rotates integrally with the rotor shaft 33.

[0024] Power connector 35 is connected to power supply unit 36a. Power supply unit 36a supplies power from the first control board 52 (described later) of control unit 5 to stator 32 via power connector 35. Power supply unit 36a protrudes to the outside of motor housing 31 and extends along the through hole 2a penetrating the interior of housing 2 in the X-axis direction toward the positive X-axis side. Most of power supply unit 36a is covered with synthetic resin. Rotor shaft 33 is a rotating shaft used to drive pump 6. The positive X-axis end of rotor shaft 33 is housed at a position closer to the negative X-axis side than the back surface (second surface) 22 of housing 2.

[0025] The stroke simulator (not shown) contains a spring-supported plunger. Movement of the plunger absorbs the brake fluid being discharged from the master cylinder, simultaneously generating a reaction force on the brake pedal. Although not shown, the stroke simulator is secured to the right side of housing 2 with screws.

[0026] Pump 6 is driven by the rotation of motor 3 to draw in brake fluid from a reservoir (not shown) and discharge it to the wheel cylinders. Pump 6 is shared by both the main system and the auxiliary system. In embodiment 1, pump 6 is a five-pump pump 6a with excellent sound and vibration performance. Each plunger pump 6a is housed in five cylinder housing holes 2b formed in the housing 2. Two cylinder housing holes 2b are arranged on the right side of the housing 2, two on the left side, and one on the bottom surface 24, and are arranged at equal intervals in the circumferential direction. Each cylinder housing hole 2b is connected to a cam chamber 2c. The cam chamber 2c forms part of the shaft housing hole 2d and opens on the front surface 21 of the housing 2.

[0027] The shaft receiving hole 2d is a generally bottomed cylindrical hole extending toward the X-axis direction, opening at the front 21 and back 22 of the housing 2. When viewed from the X-axis direction, the center of the shaft receiving hole 2d is located on the rotation axis O1. The sensor shaft 33b, integrally formed on the positive X-axis side end of the rotor shaft 33, is housed in the shaft receiving hole 2d. A cam portion 33a is formed on the positive X-axis side of the rotor shaft 33. A cam bearing 62 is mounted on the outer periphery of the cam portion 33a. When the cam portion 33a rotates driven by the rotation of the motor 3, the plungers 6a1 in each plunger pump 6a, which abut against the outer ring of the cam bearing 62, reciprocate, thereby pumping 6 to draw in and discharge brake fluid. The positive X-axis side of the cam bearing 62 abuts against a stop 63 for anti-disengagement.

[0028] Multiple solenoid valves 7, etc., are solenoid valves that operate according to control signals from the control unit 5. The valve core generates a stroke based on the energization of the solenoid, switching the opening and closing of the hydraulic circuit (disconnecting or connecting the hydraulic circuit). The solenoid valves 7, etc., control the connection state of the aforementioned circuit, adjusting the flow state of the brake fluid, thereby generating control hydraulic pressure. A portion of the solenoid valves 7, etc., is housed in multiple valve housing holes 2e. Each valve housing hole 2e extends towards the X-axis and opens on the back side 22 of the housing 2.

[0029] Multiple hydraulic sensors 8 detect the hydraulic pressure of the master cylinder, the hydraulic pressure of the wheel cylinders in the main and auxiliary systems, and the discharge pressure of the pump 6. A portion of the hydraulic sensors 8 are housed in multiple sensor housing holes 2f. Each sensor housing hole 2f extends towards the X-axis and opens on the back 22 of the housing 2. When viewed from the X-axis direction, each valve housing hole 2e and each sensor housing hole 2f are arranged separately from each other.

[0030] The control unit 5 receives input from hydraulic sensors 8 and other components mounted on the housing 2, a travel sensor that detects the travel of the brake pedal, and information related to the driving state from the vehicle side. Following a built-in program, the control unit 5 uses the input information to actuate multiple solenoid valves 7 and other components, as well as the electric motor 3, thereby controlling the hydraulic pressure of the wheel cylinders of each wheel. This enables the execution of various braking controls (anti-lock braking control to suppress wheel slippage caused by braking, power assist control to reduce the driver's braking force, braking control for vehicle motion control, automatic braking control such as following vehicle control, regenerative coordinated braking control, etc.). Vehicle motion control includes vehicle behavior stabilization controls such as anti-skid. In regenerative coordinated braking control, the wheel cylinder hydraulic pressure is controlled in coordination with regenerative braking to achieve a target deceleration (target braking force).

[0031] The control unit 5 includes a housing 51, a first control board 52, and a second control board 53. The first control board 52 and the second control board 53 are control board portions. The second control board 53 is formed to be housed among a plurality of solenoid valves 7 and is smaller in size than the first control board 52. The housing 51 has a main body portion 511 and a cover 512. The negative X-axis side of the main body portion 511 is concave, covering the solenoids 7a of the plurality of solenoid valves 7, etc. The main body portion 511 is fastened to the back surface 22 of the outer casing 2 by screws (not shown). The main body portion 511 has a first board housing portion 511a on the positive X-axis side. The first control board 52 is housed in the first board housing portion 511a. The outer casing side of the first board housing portion 511a, i.e., the negative X-axis side, has a second board housing portion 511b. The second control board 53 is housed in the second board housing portion 511b. When viewed from the axial direction, at least a portion of the second control board 53 is positioned overlapping the rotation axis O1. The first control board 52 and the second control board 53 are electrically connected via a busbar (not shown). The cover 512 is a cover component fixed to the positive X-axis side of the main body 511 and covering the first board storage portion 511a.

[0032] The first control board 52 is disposed parallel to the back surface 22 of the outer casing 2 within the board housing 511a. The first control board 52 includes a motor control circuit, a motor drive circuit, a solenoid drive circuit, and a solenoid control circuit for controlling the energizing state of the motor 3 and each solenoid 7a. The motor control circuit includes a microcomputer (or ASIC), a memory, etc., and is the circuit that drives the motor drive circuit (driving element). The motor drive circuit includes a MOSFET or other driving element and is the circuit that drives the motor 3. The solenoid control circuit includes a microcomputer (or ASIC), a memory, etc., and is the circuit that drives the solenoid drive circuit (driving element). The solenoid drive circuit includes a MOSFET or other driving element and is the circuit that drives each solenoid 7a.

[0033] The second control board 53 is parallel to the first control board 52 in the second board housing portion 511b and is disposed at a predetermined distance from the first control board 52 on the negative X-axis direction side. For example... Figure 2 As shown, a magnetic flux detection unit (motor speed sensor, hereinafter referred to as sensor) 9c is mounted on the surface of the second control board 53 on the negative X-axis side. Figure 2 yes Figure 1 The main part is enlarged. Sensor 9c approaches magnet 9a mounted on sensor shaft 33b via magnet holder 33c, and is axially opposite to magnet 9a. Sensor 9c has a detection element such as a Hall element, and detects the rotation angle (mechanical angle) of rotor shaft 33, i.e., motor speed, by detecting the change in magnetic flux density accompanying the rotation of magnet 9a. The rotation angle of rotor shaft 33 detected by sensor 9c is output to motor control circuit and solenoid control circuit of first control board 52 for the control of motor 3 and each solenoid 7a.

[0034] Figure 3 This is a perspective view of the shaft receiving hole 2d as seen from the back 22 side of the outer casing 2, as shown below. Figure 2 and Figure 3 As shown, a sealing member 10 is installed in the opening 22a of the shaft receiving hole 2d on the back side 22 of the housing 2. The sealing member 10 includes a fixing part 11 and a membrane 12. Figure 4 (a) is an exploded perspective view of the sealing component 10 of Embodiment 1. Figure 4 (b) is a cross-sectional perspective view of the sealing component 10 of Embodiment 1.

[0035] The fixing part 11 is formed into a generally annular shape using thermoplastic resin through injection molding or the like. The fixing part 11, used to fix the sealing member 10 to the opening 22a and to hold the fixing film 12, has a cylindrical part 11a, an outer flange part 11b, and an inner flange part 11c. The fixing part 11 is fixed to the periphery of the opening 22a by pressing or bonding, ensuring liquid tightness between the two. The cylindrical part 11a is inserted into the shaft receiving hole 2d. The outer flange part 11b abuts against the bottom surface of the countersunk hole 22b formed on the periphery of the opening 22a. The positive X-axis end of the inner flange part 11c is located on the negative X-axis side compared to the positive X-axis end of the outer flange part 11b.

[0036] The film 12, used to seal the opening 22a, is formed in a disc shape using a waterproof and breathable material. The film 12 is thinner than each part of the fixing part 11 (cylindrical part 11a, outer flange part 11b, and inner flange part 11c), and thinner than the thickness of the fixing part 11 in the X-axis direction. The film 12 is bonded and attached to the positive X-axis end of the inner flange part 11c by heat fusion or other methods, thereby ensuring liquid tightness between them. The positive X-axis end of the film 12 is located on the negative X-axis side compared to the positive X-axis end of the outer flange part 11b.

[0037] Next, the effects of Implementation Method 1 will be explained.

[0038] In recent years, from the perspective of improving hydraulic responsiveness, brushless motors are being adopted in braking control devices for autonomous driving. In the control of brushless motors, a sensor to detect rotational state is essential. In conventional braking control devices, a magnet mounted on the front end of the motor shaft and a flux detection sensor mounted on the control board are positioned opposite each other across a sealing component, and the sensor detects the motor's rotational position. The sealing component prevents brake fluid from seeping in from the housing side to the sensor side, thus preventing blockage of the sensor-side opening in the shaft housing hole of the housing.

[0039] However, conventional sealing components are molded from a single piece of resin, requiring precise molding thickness and making it impossible to place the magnet and sensor close together. This makes them susceptible to electrical interference from the solenoid of the solenoid valve, the circuit board, and high-temperature demagnetization, leading to a deterioration in the sensor's magnetic flux detection accuracy. Furthermore, while increasing the magnet's size can suppress this deterioration, it comes at the cost of increased price.

[0040] In contrast, the braking control device 1 in Embodiment 1 includes a sealing member 10, which is installed in the opening 22a of the shaft receiving hole 2d and has a thin film 12 that seals the opening 22a. That is, by setting the area where the magnet 9a and the sensor 9c face each other as the thin film 12, the magnet 9a and the sensor 9c can be positioned close together, thus making them less susceptible to electrical interference from the solenoid 7a of the solenoid valve 7, the second control board 53, and high-temperature demagnetization. As a result, waterproofing of the sensor 9c side is ensured, and the detection accuracy of the sensor 9c is improved. Furthermore, since a large magnet is not required, cost reduction is achieved.

[0041] The sealing member 10 of Embodiment 1 has a fixing portion 11 for fixing the film 12 to the housing 2, and the film 12 is formed to be thinner than the thickness of the fixing portion 11 in the axial direction of the rotor shaft 33. That is, the thickness of the film 12 can be designed without depending on the thickness of the resin-made fixing portion 11, so the fixing portion 11 can be formed to be thicker to ensure the necessary strength, and the film 12 can be formed to be thinner so that the magnet 9a and the sensor 9c can be configured closer together.

[0042] In Embodiment 1, the thin film 12 is formed of a waterproof material. This allows for more reliable prevention of brake fluid from seeping into the second control board 53, thereby improving the reliability of the brake control device 1.

[0043] Furthermore, the membrane 12 is formed of a waterproof and breathable material. Therefore, even when internal pressure fluctuations occur on the motor 3 and control unit 5 sides due to temperature changes, air circulates between the motor 3, control unit 5, and external air through the membrane 12 and the vent on the control unit 5 side, thus maintaining a constant state of equilibrium with the atmosphere. As a result, even when the internal pressure rises due to temperature increases within the motor 3 and control unit 5 during continuous high-load operation of the pump 6, damage to the low-pressure seals of the pump 6, the sealing components of the housing 51, etc., can be suppressed. Additionally, during the airtightness check performed after the assembly of the brake control device 1, by sealing in internal pressure through the vent on the control unit 5 side, the airtightness of the entire device, including the motor 3 side, can be confirmed in one step. This reduces the number of inspection steps during the assembly of the brake control device 1, thereby increasing productivity.

[0044] The electric motor 3 in Embodiment 1 is a brushless electric motor. Therefore, compared with the case of using a brushed electric motor, the hydraulic responsiveness is improved, making it suitable as a braking control device for vehicles requiring high responsiveness, such as autonomous driving. In addition, by using a brushless electric motor, advantages such as longer lifespan, improved maintainability, and quieter operation can be obtained.

[0045] In Embodiment 1, the sensor 9c is mounted on a second control board 53 disposed opposite to the magnet 9a. That is, by mounting the sensor 9c on the second control board 53 opposite to the magnet 9a, the layout of the sensor 9c can be improved.

[0046] [Implementation Method 2]

[0047] Figure 5 (a) is an exploded perspective view of the sealing component 10 of Embodiment 2. Figure 5 (b) is a cross-sectional perspective view of the sealing component 10 of Embodiment 2.

[0048] In Embodiment 2, a cross-shaped reinforcing rib 11d is provided on the inner periphery of the fixing portion 11, which differs from Embodiment 1. By adding the reinforcing rib 11d, the retaining strength of the film 12 can be further improved.

[0049] [Other Implementation Methods]

[0050] The embodiments for implementing the present invention have been described above, but the specific structure of the present invention is not limited to the structure of the embodiments. Design changes and the like that that do not depart from the spirit of the invention are also included in the present invention.

[0051] For example, in sealing components, the material and shape of the fixing part can be appropriately set.

[0052] This application claims priority based on Japanese Patent Application No. 2023-216497, filed on December 22, 2023. The entire disclosure of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2023-216497, filed on December 22, 2023, is incorporated herein by reference in its entirety.

[0053] Explanation of reference numerals in the attached figures

[0054] 1: Braking control device

[0055] 2: Outer shell

[0056] 2d: Shaft storage hole

[0057] 3: Electric motor

[0058] 9a: Magnet

[0059] 9c: Flux Detection Department (Detection Department)

[0060] 10: Sealing components

[0061] 11: Fixing part

[0062] 12: Film

[0063] 21: Front (First side)

[0064] 22: Back side (second side)

[0065] 33b: Sensor shaft (axis)

[0066] 53: Second control board (board)

Claims

1. A brake control device characterized by comprising: Possessing: an electric motor; a shaft that rotates by the electric motor, having a first end portion and a second end portion; a control unit that controls rotation of the electric motor; a housing, the housing having a first face, a second face, and a shaft receiving hole, the first face being provided with the electric motor, the second face being provided with the control unit, separated from the first face by a prescribed distance in the axial direction of the shaft, the shaft receiving hole passing between the first face and the second face, for insertion of the second end portion side of the shaft, the brake control device further having: a magnet installed to the second end portion of the shaft; a sealing member installed to an opening portion of the shaft receiving hole of the second face, having a film that seals the opening portion; a detection portion provided to the control unit in a manner that opposes the magnet across the film, that detects a rotational state of the shaft.

2. The brake control device according to claim 1, characterized in that the sealing member has a fixing portion for fixing the film to the housing, the film is formed thinner than the fixing portion in the axial direction of the shaft.

3. The brake control device according to claim 1, characterized in that the film is formed of a waterproof material.

4. The brake control device according to claim 1, characterized in that the film is formed of a waterproof, moisture-permeable material.

5. The brake control device according to claim 1, characterized in that the electric motor is a brushless electric motor.

6. The brake control device according to claim 1, characterized in that the detection portion is installed to a substrate provided in opposition to the magnet.

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