Braking device

Abstract

To enable the detection of abnormalities in the rotation angle sensor. [Solution] The first processing circuit functions as a rotation angle detection unit M17 that acquires a rotation angle detection value θmt based on phase pulse signals SPA and SPB output from a rotation angle sensor; a motor control unit M21 that controls the first electric motor 513 so that it can output a torque including correction torque based on feedback control that takes the deviation Δθ between the target rotation angle θTr and the rotation angle detection value θmt as input; a phase pulse abnormality determination unit M25 that determines that a phase pulse sticking abnormality has occurred if the absolute value of the deviation Δθ is greater than or equal to the deviation threshold Δθth and the state in which the signal levels of the phase pulse signals SPA and SPB are maintained continues even after exceeding the abnormality determination time; and a deviation threshold derivation unit M23 that derives a deviation threshold Δθth so that the correction torque when the absolute value of the deviation Δθ is greater than or equal to the deviation threshold Δθth is greater than the loss torque of the first electric motor 513.

Description

Technical Field

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[0001] The present invention relates to a braking device that generates a braking force for a vehicle by pressing a friction portion against a rotating body that rotates integrally with a wheel.

Background Art

[0002] The braking device disclosed in Patent Document 1 includes an electric cylinder that supplies brake fluid to a wheel cylinder. The electric cylinder has an electric motor as a power source and a rotation angle sensor that outputs a signal corresponding to the rotation speed of the rotor of the electric motor. When the control unit of the braking device drives the electric motor, it detects the rotation angle of the rotor of the electric motor based on the output signal of the rotation angle sensor.

Prior Art Documents

Patent Documents

[0003]

Patent Document

Summary of the Invention

Problems to be Solved by the Invention

[0004] As a rotation angle sensor, a sensor that outputs a pulse signal including a phase pulse generated every time the rotation angle of the rotor rotates by a predetermined angle is known. When such a sensor is adopted as the rotation angle sensor, the control unit detects the rotation angle by counting the number of rising edges and falling edges of the phase pulses included in the pulse signal. Therefore, when the signal level of the pulse signal does not change due to a failure of the rotation angle sensor, the control unit cannot detect the rotation angle. As a result, the control unit cannot appropriately control the electric motor.

Means for Solving the Problems

[0005] A braking device for solving the above problems includes an electric motor and a rotation angle sensor, and a braking unit that generates a braking force on the vehicle in accordance with the drive of the electric motor. The rotation angle sensor is a sensor that outputs a phase pulse signal including a phase pulse that is generated each time the rotor, which rotates in accordance with the drive of the electric motor, rotates by a predetermined angle. The braking device includes: a rotation angle detection unit that acquires a rotation angle detection value, which is a detected value of the rotation angle of the rotor, based on the phase pulse signal output from the rotation angle sensor; a motor control unit that controls the electric motor to output a torque including a correction torque, which is a torque that can eliminate the discrepancy between the target rotation angle and the rotation angle detection value, based on feedback control that takes the deviation between the target rotation angle, which is a target value of the rotation angle of the rotor, and the rotation angle detection value as input; a phase pulse abnormality determination unit that determines that a phase pulse sticking abnormality has occurred, which is an abnormality in which the phase pulse is not generated by the rotation angle sensor, when the absolute value of the deviation is greater than or equal to a deviation threshold, and the state in which the signal level of the phase pulse signal is maintained continues even after exceeding the abnormality determination time; and a deviation threshold derivation unit that derives the deviation threshold such that the correction torque when the absolute value of the deviation is greater than or equal to the deviation threshold is greater than the loss torque of the electric motor. [Effects of the Invention]

[0006] The above braking device has the effect of being able to detect abnormalities in the rotation angle sensor. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a schematic diagram showing a vehicle equipped with one embodiment of a braking system. [Figure 2] Figure 2 is a schematic diagram showing the rotation angle sensor and the first controller included in the braking device of Figure 1. [Figure 3] Figure 3(a) is a timing chart showing the progression of the count, and Figure 3(b) is a timing chart showing the Z pulse signal output from the rotation angle sensor in Figure 1. [Figure 4]Figure 4 is a block diagram showing the functional configuration of the first controller in Figure 1. [Figure 5] Figure 5 shows the relationship between the output torque of the first electric motor and the servo pressure of the braking device shown in Figure 1. [Figure 6] Figure 6 is a flowchart showing a series of processes for determining whether or not a phase pulse sticking abnormality has occurred in the rotation angle sensor shown in Figure 1. [Figure 7] Figure 7 is a flowchart showing a series of processes for determining whether or not a Z-pulse sticking abnormality has occurred in the rotation angle sensor shown in Figure 1. [Figure 8] Figures 8(a) to 8(c) are timing charts showing the changes in various parameters as the target servo pressure is increased. [Modes for carrying out the invention]

[0008] One embodiment of the braking device will be described with reference to Figures 1 to 8. Figure 1 shows a vehicle 10 equipped with a braking system 100. The vehicle 10 has two first wheels 11 and two second wheels 12. The vehicle 10 is equipped with multiple friction brakes 15 corresponding to each of the multiple wheels 11, 12.

[0009] <Configuration of friction brakes> Multiple friction brakes 15 generate braking force on the corresponding wheels 11 and 12. Each friction brake 15 comprises a wheel cylinder 16, a rotating body 17, and a friction part 18. Since the rotating body 17 rotates integrally with the wheels 11 and 12, the friction part 18 presses against the rotating body 17, generating braking force on the wheels 11 and 12. The pressing force, which is the force pressing the friction part 18 against the rotating body 17, increases with increasing wheel pressure, which is the hydraulic pressure inside the wheel cylinder 16. Therefore, the friction brake 15 can generate greater braking force on the wheels 11 and 12 as the wheel pressure increases.

[0010] Hereafter, the braking force generated at the wheels 11 and 12 by the operation of the friction brake 15 will be referred to as "friction braking force". The sum of the friction braking forces generated at multiple wheels 11 and 12 will be referred to as "friction braking force FbM of the vehicle 10" or simply "friction braking force FbM".

[0011] <Configuration of the braking system> The braking system 100 adjusts the frictional braking force FbM of the vehicle 10 by controlling the wheel pressure of a plurality of wheel cylinders 16. The braking system 100 comprises an upstream unit 110 and a downstream unit 120. Each of the upstream unit 110 and the downstream unit 120 is configured to control the wheel pressure of a plurality of wheel cylinders 16.

[0012] <Configuration of the upstream unit> The upstream unit 110 includes a hydraulic pressure generator 20 and a first controller 210 that controls the hydraulic pressure generator 20. The first controller 210 will be described later.

[0013] The hydraulic pressure generator 20 includes a reservoir tank 21, a braking operating member 22, a brake sensor 23, a master device 30, and an electrically operated pressurized unit 50. The pressurized unit 50 corresponds to the "braking unit".

[0014] The reservoir tank 21 stores brake fluid and is open to the atmosphere. The braking operation member 22 is a member operated by the driver of the vehicle 10 when adjusting the deceleration of the vehicle 10. An example of the braking operation member 22 is the brake pedal. The act of the driver operating the braking operation member 22 is called "braking operation". When braking operation is being performed, the hydraulic pressure generator 20 can generate wheel pressure in multiple wheel cylinders 16 according to the amount of operation of the braking operation member 22.

[0015] The brake sensor 23 detects information regarding the operation of the braking operation member 22 by the driver. The brake sensor 23 detects, for example, the amount of operation of the braking operation member 22 by the driver as information regarding the operation of the braking operation member 22. Hereinafter, the amount of operation based on the detection signal of the brake sensor 23 is referred to as "braking operation amount Ba".

[0016] <Master device> The master device 30 includes a master cylinder 31, a stroke simulator 32, a plurality of flow paths 331, 332, 333 connected to the master cylinder 31, and a plurality of control valves 341, 342 that control the flow of the brake fluid. The master device 30 includes a hydraulic pressure sensor 351 that detects the hydraulic pressure of the brake fluid.

[0017] The stroke simulator 32 can generate a reaction force corresponding to the amount of operation of the braking operation member 22. The master cylinder 31 includes a main cylinder 41, a cover cylinder 42, a master piston 43, and an input piston 44. Each of the master piston 43 and the input piston 44 can move relative to the main cylinder 41 and the cover cylinder 42. The master cylinder 31 includes a master spring 45 that biases the master piston 43 and an input spring 46 that biases the input piston 44.

[0018] The main cylinder 41 has a plate-shaped bottom wall 411, a cylindrical peripheral wall 412 that extends from the bottom wall 411 along the axis of the bottom wall 411, and a first annular wall 413 that extends from the rear end of the peripheral wall 412 toward the axis of the peripheral wall 412. A hole into which the rear end portion of the master piston 43 described later is inserted is formed in the first annular wall 413.

[0019] Within the main cylinder 41, the master chamber Rm is partitioned by the bottom wall 411, the peripheral wall 412, and the master piston 43. Hereafter, in the master cylinder 31, the direction of movement of the master piston 43 that reduces the volume of the master chamber Rm, which is to the left in Figure 1, will be referred to as "forward." Conversely, the opposite direction to forward will be referred to as "rearward." Rearward is also the direction that increases the volume of the master chamber Rm.

[0020] Rearward of the master chamber Rm within the main cylinder 41, the first fluid chamber R1 is partitioned by the circumferential wall 412 and the master piston 43. Rearward of the first fluid chamber R1 within the main cylinder 41, the servo chamber Rs is partitioned by the circumferential wall 412, the first annular wall 413 and the master piston 43. Within the main cylinder 41, the master chamber Rm, the first fluid chamber R1, and the servo chamber Rs are not connected to each other.

[0021] The cover cylinder 42 has a cylindrical circumferential wall 421 and a second annular wall 422 extending from the rear end of the circumferential wall 421 toward the axis of the circumferential wall 421. The circumferential wall 421 is attached to the first annular wall 413 so that its axis coincides with that of the circumferential wall 412 of the main cylinder 41. The second annular wall 422 is provided with a hole into which the rear end of the input piston 44, which will be described later, is inserted.

[0022] Within the cover cylinder 42, the second fluid chamber R2 is partitioned by the peripheral wall 421, the second annular wall 422, and the first annular wall 413 of the main cylinder 41. In the master cylinder 31, the second fluid chamber R2 is located behind the servo chamber Rs.

[0023] The master piston 43 is housed in the master cylinder 31 with a seal ring interposed between the master piston 43 and the inner surface of the circumferential wall 412 and the inner surface of the first annular wall 413 of the main cylinder 41. When the master piston 43 moves axially, it slides along the inner surface of the circumferential wall 412 and the inner surface of the first annular wall 413. The rear end of the master piston 43 protrudes rearward from the first annular wall 413 and is located within the second fluid chamber R2.

[0024] The input piston 44 is housed in the master cylinder 31 with a seal ring interposed between the input piston 44 and the inner circumferential surface of the second annular wall 422 of the cover cylinder 42. When the input piston 44 moves axially, it slides along the inner circumferential surface of the second annular wall 422. The rear end of the input piston 44 protrudes rearward from the second annular wall 422. A braking operating member 22 is connected to the rear end of the input piston 44. In the second fluid chamber R2, a gap is formed between the input piston 44 and the master piston 43. When the braking operating member 22 is operated, the input piston 44 moves in a direction toward the master piston 43.

[0025] The master spring 45 is positioned between the bottom wall 411 of the main cylinder 41 and the master piston 43. The master spring 45 biases the master piston 43 backward, so when the master piston 43 moves forward, the master spring 45 is elastically compressed.

[0026] The input spring 46 is positioned between the first annular wall 413 of the main cylinder 41 and the input piston 44. The input spring 46 biases the input piston 44 backward, so when the input piston 44 moves forward, the input spring 46 is elastically compressed.

[0027] In the master cylinder 31, the master chamber Rm is connected to the reservoir tank 21. More specifically, the rear end portion of the master chamber Rm is connected to the reservoir tank 21 via a port formed in the peripheral wall 412 of the main cylinder 41. Therefore, when the master piston 43 moves forward from the initial position shown in Figure 1, the connection between the master chamber Rm and the reservoir tank 21 is released. From this point onward, the hydraulic pressure in the master chamber Rm increases as the master piston 43 moves forward. For example, if the hydraulic pressure in the servo chamber Rs increases, the hydraulic pressure in the servo chamber Rs will move the master piston 43 forward. This will increase the hydraulic pressure in the master chamber Rm.

[0028] The first flow path 331 connects the first hydraulic circuit 711 of the braking actuator 70 (described later) to the master chamber Rm. The second flow path 332 connects the first liquid chamber R1 to the third flow path 333. The stroke simulator 32 is also connected to the second flow path 332. The third flow path 333 connects the second liquid chamber R2 to the reservoir tank 21.

[0029] The first control valve 341 is a normally closed solenoid valve. The second control valve 342 is a normally open solenoid valve. The first control valve 341 is located in the third flow path 333, in the portion between the connection point with the second flow path 332 and the second liquid chamber R2. The second control valve 342 is located in the third flow path 333, in the portion opposite to the first control valve 341, with the connection point with the second flow path 332 in between. When the control device 200 is operating, the first control valve 341 is opened and the second control valve 342 is closed.

[0030] The hydraulic pressure sensor 351 detects the hydraulic pressure in the second liquid chamber R2. For example, the hydraulic pressure sensor 351 is installed in the portion of the third flow path 333 between the connection point with the second liquid chamber R2 and the first control valve 341. In the following description, the hydraulic pressure based on the detection signal from the hydraulic pressure sensor 351 will be referred to as the "input hydraulic pressure Pgs".

[0031] <Pressure Unit> The pressurizing unit 50 is equipped with an electric cylinder 51. The pressurizing unit 50 can adjust the wheel pressure of multiple wheel cylinders 16 by operating the electric cylinder 51.

[0032] The pressurizing unit 50 is equipped with a fourth passage 54, a fifth passage 55, and a sixth passage 56 as brake fluid passages. The fourth passage 54 is connected to the input port 515 of the electric cylinder 51 and the reservoir tank 21. The fifth passage 55 is connected to the servo chamber Rs of the master cylinder 31 and the output port 516 of the electric cylinder 51. The sixth passage 56 is connected to the second hydraulic circuit 712 of the brake actuator 70 (described later) and the fifth passage 55. Therefore, the electric cylinder 51 can supply brake fluid discharged from the output port 516 to both the servo chamber Rs and the second hydraulic circuit 712.

[0033] The pressurizing unit 50 includes a differential pressure regulating valve 551 installed in the portion of the fifth flow path 55 between the connection point with the sixth flow path 56 and the servo chamber Rs. The differential pressure regulating valve 551 is a normally open linear solenoid valve that adjusts the differential pressure between the portion of the fifth flow path 55 between the differential pressure regulating valve 551 and the servo chamber Rs and between the portion of the fifth flow path 55 between the differential pressure regulating valve 551 and the electric cylinder 51. By adjusting the indicated opening degree of the differential pressure regulating valve 551, the pressurizing unit 50 can adjust the amount of brake fluid supplied to the servo chamber Rs, i.e., the hydraulic pressure in the servo chamber Rs.

[0034] Furthermore, a check valve 552 is provided in parallel with the differential pressure regulating valve 551 in the fifth flow path 55. The check valve 552 allows the flow of brake fluid through it from the servo chamber Rs toward the electric cylinder 51. On the other hand, the check valve 552 restricts the flow of brake fluid through it toward the servo chamber Rs toward the servo chamber Rs.

[0035] The electric cylinder 51 comprises a cylinder 511, a piston 512, a first electric motor 513, and a conversion mechanism 514. The piston 512 is slidably mounted within the cylinder 511. The first electric motor 513 functions as the power source for the electric cylinder 51. The output shaft 513a of the first electric motor 513 is connected to the conversion mechanism 514. The output shaft 513a corresponds to a "rotor" that rotates in a direction corresponding to the drive of the first electric motor 513. The conversion mechanism 514 converts the rotational motion of the output shaft 513a into the linear motion of the piston 512.

[0036] An example of the first electric motor 513 is a brushless motor having multiple phase coils. In this case, the motor rotation angle can be adjusted by adjusting the current flowing through the multiple phase coils. The motor rotation angle is the rotation angle of the output shaft of the first electric motor 513.

[0037] Inside cylinder 511, a hydraulic chamber Re into which brake fluid is introduced is partitioned by the peripheral wall of cylinder 511 and piston 512. The position of piston 512 inside cylinder 511 can be changed by driving first electric motor 513. Hereafter, the direction of linear movement of piston 512 when reducing the volume of hydraulic chamber Re will be described as "forward direction Za," and the opposite direction of forward direction Za will be described as "reverse direction Zb." Reverse direction Zb is also the direction of linear movement of piston 512 when increasing the volume of hydraulic chamber Re.

[0038] An input port 515 and an output port 516 are formed on the peripheral wall of the cylinder 511 as ports connecting the hydraulic chamber Re to the outside. A through hole 517 is formed in the piston 512. The through hole 517 is positioned so that the input port 515 and the hydraulic chamber Re can communicate when the piston 512 is in its rearmost position. As a result, when the piston 512 is in its rearmost position, the hydraulic chamber Re of the cylinder 511 communicates with the reservoir tank 21 via the through hole 517, the input port 515, and the fourth flow path 54. The input port 515 is open when the piston 512 is in its rearmost position and is configured to be closed by the piston 512 when the piston 512 moves forward in the Za direction from the rearmost position. Even after the input port 515 is closed by the piston 512, if the piston 512 moves forward in the Za direction, the hydraulic pressure in the hydraulic chamber Re increases.

[0039] The output port 516 is connected to the master cylinder 31 and the sixth flow path 56 via the fifth flow path 55. The output port 516 is always open regardless of the position of the piston 512. Therefore, when the input port 515 is blocked by the piston 512, the brake fluid from the hydraulic chamber Re is discharged from the output port 516 into the fifth flow path 55 as the piston 512 moves in the forward direction Za within the cylinder 511 in response to the drive of the first electric motor 513. On the other hand, as the piston 512 moves in the backward direction Zb within the cylinder 511 in response to the drive of the first electric motor 513, the brake fluid from the fifth flow path 55 is drawn into the hydraulic chamber Re from the output port 516.

[0040] In the hydraulic pressure generator 20, when brake fluid is discharged from the output port 516 of the electric cylinder 51, the brake fluid flows through the fifth passage 55. A portion of the brake fluid flowing through the fifth passage 55 flows towards the wheel cylinder 16 for the second wheel 12 via the sixth passage 56. The remaining brake fluid flows into the servo chamber Rs of the master device 30. As a result, the hydraulic pressure in the servo chamber Rs increases, causing the master piston 43 to move forward and increasing the hydraulic pressure in the master chamber Rm. This causes the brake fluid in the master chamber Rm to flow through the first passage 331 towards the wheel cylinder 16 for the first wheel 11.

[0041] On the other hand, when the electric cylinder 51 is drawing brake fluid through the output port 516, brake fluid flows out from each of the wheel cylinders 16 for the multiple wheels 11 and 12. As a result, the brake fluid flows in the sixth passage 56 toward the fifth passage 55. Also, in the first passage 331, brake fluid flows toward the master chamber Rm. As a result, the hydraulic pressure in the master chamber Rm increases, causing the master piston 43 to move backward. Consequently, the brake fluid in the servo chamber Rs flows out into the fifth passage 55. This causes the brake fluid to flow toward the electric cylinder 51 in the fifth passage 55.

[0042] The pressurizing unit 50 is equipped with a servo pressure sensor 58 and a rotation angle sensor 59. The servo pressure sensor 58 detects the servo pressure, which is the discharge pressure of the brake fluid from the electric cylinder 51. The rotation angle sensor 59 detects the motor rotation angle of the first electric motor 513. Hereafter, the servo pressure based on the detection signal of the servo pressure sensor 58 will be referred to as the "servo pressure detection value Ps". The motor rotation angle based on the detection signal of the rotation angle sensor 59 will be referred to as the "rotation angle detection value θmt".

[0043] <Downstream Unit> The downstream unit 120 includes a braking actuator 70 and a second controller 220 for controlling the braking actuator 70. An example of the braking actuator 70 is the actuator disclosed in "Japanese Patent Application Publication No. 2024-170913". The braking actuator 70 may have a different configuration from the actuator disclosed in the above publication, as long as it can individually adjust the wheel pressure of multiple wheel cylinders 16. The second controller 220 will be described later.

[0044] <Rotation Angle Sensor> Refer to Figures 2 and 3 to describe in detail the configuration of the rotation angle sensor 59. As shown in Figure 2, an example of a rotation angle sensor 59 is a three-phase rotary encoder consisting of A-phase, B-phase, and Z-phase. The output signal of the A-phase is denoted as "A pulse signal SPA". The output signal of the B-phase is denoted as "B pulse signal SPB". The output signal of the Z-phase is denoted as "Z pulse signal SPZ".

[0045] Each of the A pulse signal SPA and the B pulse signal SPB is a phase pulse signal that includes a phase pulse generated each time the output shaft 513a of the first electric motor 513 rotates by a predetermined angle. The predetermined angle is smaller than the rotation angle of one full rotation of the output shaft 513a. The phase pulse included in the A pulse signal SPA is denoted as "A pulse PLSA". The phase pulse included in the B pulse signal SPB is denoted as "B pulse PLSB".

[0046] The phases of phase A and phase B are shifted by a specified period. Therefore, the first controller 210 can determine the rotation direction of the output shaft 513a, i.e., the rotation direction of the first electric motor 513, based on the input order of the rising edge of the A pulse PLSA, the falling edge of the A pulse PLSA, the rising edge of the B pulse PLSB, and the falling edge of the B pulse PLSB. The A pulse PLSA and B pulse PLSB are generated a total of a specified number of times during one rotation of the first electric motor 513. The specified number of occurrences is determined by the specifications of the first electric motor 513.

[0047] The Z pulse signal SPZ is a signal that includes the Z pulse PLSZ which is generated each time the output shaft 513a of the first electric motor 513 rotates. Figure 3(a) shows the transition of the edge count Cab of the A pulse PLSA and B pulse when the output shaft 513a rotates in a direction that moves the piston 512 of the electric cylinder 51 linearly in the forward direction Za. Figure 3(b) shows the transition of the signal level of the Z pulse PLSZ. Note that the rotation direction of the output shaft 513a that moves the piston 512 linearly in the forward direction Za is sometimes referred to as the "count-up direction," and the direction in which the count-up direction is determined is sometimes referred to as the "count-down direction." The count-down direction is also the rotation direction of the output shaft 513a that moves the piston 512 linearly in the backward direction Zb.

[0048] In the first controller 210, the count Cab is acquired based on the A pulse signal SPA and B pulse signal SPB input from the rotation angle sensor 59. When the output shaft 513a rotates in the count-up direction, the count Cab increases as shown in Figure 3(a). Then, as shown in Figures 3(a) and (b), when the count Cab reaches a specified count Cabth and the output shaft 513a continues to rotate in the count-up direction, the signal level of the Z pulse signal SPZ changes from "Low" to "High," that is, a Z pulse PLSZ is generated. The generation of a Z pulse PLSZ means that the output shaft 513a has completed one rotation. In other words, the specified count Cabth is the count for one rotation of the output shaft 513a. When the signal level of the Z pulse signal SPZ changes from "Low" to "High" while the output shaft 513a is rotating in the count-up direction, the first controller 210 resets the count Cab to 0 (zero) as a hardware process.

[0049] On the other hand, as the output shaft 513a rotates in the countdown direction, the count Cab decreases. When the output shaft 513a continues to rotate in the countdown direction even after the count Cab reaches 0 (zero), the signal level of the Z pulse signal SPZ changes from "High" to "Low," meaning that the state in which the Z pulse PLSZ is generated ends. When the signal level of the Z pulse signal SPZ changes from "High" to "Low" while the output shaft 513a is rotating in the countdown direction, the first controller 210 resets the count Cab to a specified count Cabth as a hardware process.

[0050] Here, the rotation angle sensor 59 may experience a Z-pulse sticking anomaly, in which the signal level of the Z-pulse signal SPZ becomes unchangeable. When a Z-pulse sticking anomaly occurs, the count Cab exceeds the range of one rotation of the output shaft 513a, which may affect the control of the first electric motor 513. Therefore, the first controller 210, as a software process, when the count Cab reaches a specified count Cabth while the output shaft 513a is rotating in the count-up direction, the count Cab is reset to 0 (zero) without increasing when the output shaft 513a rotates further in the count-up direction. Also, when the count Cab reaches 0 (zero) while the output shaft 513a is rotating in the count-down direction, the count Cab is reset to the specified count Cabth without decreasing when the output shaft 513a rotates further in the count-down direction.

[0051] In addition to the count Cab, the first controller 210 also measures a specific count Cabz. As will be explained in more detail later, the specific count Cabz is used to determine whether or not a Z pulse sticking abnormality has occurred. If a Z pulse sticking abnormality has not occurred, the specific count Cabz will be the same value as the count Cab. In other words, even if the specific count Cabz reaches a specified count Cabth due to the output shaft 513a rotating in the count-up direction, if the output shaft 513a rotates further in the count-up direction, the specific count Cabz will be reset to 0 (zero). Similarly, even if the specific count Cabz reaches 0 (zero) due to the output shaft 513a rotating in the count-down direction, if the output shaft 513a rotates further in the count-down direction, the specific count Cabz will be reset to the specified count Cabth.

[0052] However, if a Z-pulse locking anomaly occurs, the specific count Cabz is not reset to 0 (zero) or the specified count Cabth by the software. Therefore, if the output shaft 513a rotates further in the count-up direction even after the specific count Cabz reaches the specified count Cabth, the specific count Cabz will increase without being reset to 0 (zero). Also, if the output shaft 513a rotates further in the count-down direction even after the specific count Cabz reaches 0 (zero), the specific count Cabz will decrease without being reset to the specified count Cabth. In other words, if a Z-pulse locking anomaly occurs, the specific count Cabz may become less than 0 (zero) or greater than the specified count Cabth.

[0053] <Control device configuration> As shown in Figure 1, the control device 200 of the braking device 100 can operate the hydraulic pressure generator 20 and the braking actuator 70 based on detection signals from multiple sensors 351, 58, and 59. For example, the control device 200 can control the servo pressure by driving the first electric motor 513. This allows the control device 200 to generate wheel pressure in multiple wheel cylinders 16 according to the servo pressure. Furthermore, even when the pressurizing unit 50 of the hydraulic pressure generator 20 is not operating, the control device 200 can adjust the wheel pressure of multiple wheel cylinders 16 by operating the braking actuator 70.

[0054] The control device 200 includes the first controller 210 and the second controller 220 described above. The multiple controllers 210 and 220 can send and receive various information and commands from each other via the in-vehicle network 230.

[0055] The first controller 210 has a first processing circuit 211. The second controller 220 has a second processing circuit 221. An example of the processing circuits 211 and 221 is an electronic control unit. In this case, each of the multiple processing circuits 211 and 221 has a CPU and a memory that stores a control program executed by the CPU. The first processing circuit 211 operates the hydraulic pressure generator 20 by having the CPU execute the control program in the memory. The second processing circuit 221 operates the braking actuator 70 by having the CPU execute the control program in the memory.

[0056] <Functional Configuration of the First Controller> Referring to Figures 4 and 5, the functional configuration of the first controller 210 will be described. The first processing circuit 211 of the first controller 210 functions as a plurality of functional units when the CPU executes a control program in memory. The plurality of functional units include a functional unit for driving the first electric motor 513 and a functional unit for determining abnormalities of the rotation angle sensor 59. As shown in Figure 4, the plurality of functional units include a target friction braking force derivation unit M11, a target servo pressure derivation unit M13, a target rotation angle derivation unit M15, a rotation angle detection unit M17, a deviation derivation unit M19, and a motor control unit M21. The plurality of functional units further include a deviation threshold derivation unit M23, a phase pulse abnormality determination unit M25, and a Z pulse abnormality determination unit M27.

[0057] The target friction braking force derivation unit M11 derives a target friction braking force FbMTr, which is a target value for the friction braking force FbM of the vehicle 10, at predetermined control cycles. The target friction braking force derivation unit M11 derives the target friction braking force FbMTr based on the braking operation amount Ba and the regenerative braking force FbE of the vehicle 10. For example, the target friction braking force derivation unit M11 derives the target braking force FbTr such that its value increases as the braking operation amount Ba increases. The target braking force FbTr is the target value of the sum of the regenerative braking force FbE and the friction braking force FbM. The target friction braking force derivation unit M11 derives the value obtained by subtracting the regenerative braking force FbE from the target braking force FbTr as the target friction braking force FbMTr.

[0058] The target servo pressure derivation unit M13 derives the target servo pressure PsTr based on the target friction braking force FbMTr at predetermined control cycles. The target servo pressure PsTr is the target value of the servo pressure Ps. The target servo pressure derivation unit M13 derives the target servo pressure PsTr such that its value increases as the target friction braking force FbMTr increases.

[0059] The target rotation angle derivation unit M15 derives the target rotation angle θTr based on the target servo pressure PsTr at predetermined control cycles. The target rotation angle θTr is the target value of the detected rotation angle value θmt. In the pressurizing unit 50, when the position of the piston 512 when no servo pressure is generated is considered the standby position, there is a correlation between the amount of movement of the piston 512 in the forward direction Za from the standby position and the motor rotation angle of the first electric motor 513. Furthermore, there is a correlation between the amount of movement of the piston 512 in the forward direction Za from the standby position and the servo pressure. In other words, there is a correlation between the motor rotation angle and the servo pressure.

[0060] Therefore, the target rotation angle derivation unit M15 derives the rotation angle corresponding to the target servo pressure PsTr as the target rotation angle θTr, based on a map showing the correlation between the motor rotation angle of the first electric motor 513 and the servo pressure.

[0061] The rotation angle detection unit M17 acquires the rotation angle detection value θmt at predetermined control cycles based on the detection signal from the rotation angle sensor 59, i.e., the phase pulse signals SPA, SPB and the Z pulse signal SPZ. For example, the rotation angle detection unit M17 acquires the rotation angle detection value θmt based on the count Cab shown in Figure 3(a) and the number of rotations of the output shaft 513a of the first electric motor 513.

[0062] The deviation derivation unit M19 derives the deviation Δθ between the target rotation angle θTr and the detected rotation angle value θmt at predetermined control cycles. For example, the deviation derivation unit M19 derives the value obtained by subtracting the detected rotation angle value θmt from the target rotation angle θTr as the deviation Δθ.

[0063] The motor control unit M21 controls the first electric motor 513. The motor control unit M21 includes, for example, a reference torque derivation unit M211, a correction torque derivation unit M212, a target torque derivation unit M213, and a command unit M214.

[0064] The reference torque derivation unit M211 derives a reference torque TqB, which is a reference value of the output torque of the first electric motor 513, at predetermined control cycles. The reference torque derivation unit M211 derives the reference torque TqB based on the target servo pressure PsTr. For example, the reference torque derivation unit M211 derives a larger torque as the target servo pressure PsTr is larger as the reference torque TqB.

[0065] The corrected torque derivation unit M212 derives the corrected torque TqC of the first electric motor 513 at predetermined control cycles. The corrected torque derivation unit M212 derives the corrected torque TqC by feedback control with the deviation Δθ as input. This feedback control includes at least proportional control among proportional control, integral control, and differential control.

[0066] The target torque derivation unit M213 derives a target torque TqTr, which is the target value of the output torque of the first electric motor 513, at predetermined control cycles. The target torque derivation unit M213 derives the sum of the reference torque TqB and the correction torque TqC as the target torque TqTr.

[0067] The command unit M214 derives a command value ITr for the motor current, which is the current supplied to the first electric motor 513, based on the target torque TqTr. Then, the command unit M214 activates the driver circuit for the first electric motor 513 according to the drive signal based on the command value ITr. This allows the command unit M214 to drive the first electric motor 513.

[0068] However, if the phase pulse abnormality determination unit M25, described later, determines that a phase pulse sticking abnormality has occurred in the rotation angle sensor 59, the command unit M214 stops the operation of the pressurizing unit 50 by stopping the control of the first electric motor 513.

[0069] The deviation threshold derivation unit M23 derives a deviation threshold Δθth at predetermined control cycles. The deviation threshold Δθth is a criterion for determining whether the correction torque TqC derived by feedback control with the deviation Δθ as input is greater than or equal to the lost torque TqLS of the first electric motor 513.

[0070] Here, with reference to Figure 5, the lost torque TqLS of the first electric motor 513 will be explained. Figure 5 shows the relationship between the motor torque Tq, which is the output torque of the first electric motor 513, and the servo pressure Ps. Specifically, the pressure-increasing characteristic line L1 in Figure 5 shows an example of the relationship between the motor torque Tq and the servo pressure Ps when the servo pressure Ps is increased. The pressure-decreasing characteristic line L2 in Figure 5 shows an example of the relationship between the motor torque Tq and the servo pressure Ps when the servo pressure Ps is decreased.

[0071] As shown in Figure 5, the magnitude of the difference between the motor torque Tq shown on the pressure-boosting characteristic curve L1 and the motor torque Tq shown on the pressure-reducing characteristic curve L2 corresponds to the lost torque TqLS. Specifically, among the motor torque Tq based on the pressure-boosting characteristic curve L1, the motor torque Tq corresponding to the servo pressure Ps at that time is defined as the pressure-boosting torque Tq1. Among the motor torque Tq based on the pressure-reducing characteristic curve L2, the motor torque Tq corresponding to the servo pressure Ps at that time is defined as the pressure-reducing torque Tq2. In this case, the magnitude of the difference between the pressure-boosting torque Tq1 and the pressure-reducing torque Tq2 is the lost torque TqLS. Therefore, the larger the servo pressure Ps at that time, the larger the lost torque TqLS will be.

[0072] Returning to Figure 4, the deviation threshold derivation unit M23 derives the lost torque TqLS based on the pressure increase characteristic line L1 and the pressure decrease characteristic line L2 shown in Figure 5, and the servo pressure Ps at those times. Here, the corrected torque TqC is the torque that can eliminate the discrepancy between the target rotation angle θTr and the detected rotation angle value θmt. Of these corrected torques TqC, the torque derived by the proportional control of the feedback control that takes the deviation Δθ as input is the deviation correction torque TqDC. In other words, the corrected torque TqC includes the deviation correction torque TqDC. Furthermore, if the above feedback control is proportional control only, the corrected torque TqC will be equal to the deviation correction torque TqDC. That is, the deviation correction torque TqDC is the absolute value of the product of the proportional gain Gp, which is the gain of the proportional control, and the deviation Δθ. As will be described later, the phase pulse abnormality determination unit M25 determines whether or not a phase pulse sticking abnormality has occurred when the absolute value of the above deviation Δθ is greater than or equal to the deviation threshold Δθth.

[0073] Therefore, the deviation threshold derivation unit M23 derives the deviation threshold Δθth based on the gain of the feedback control performed by the correction torque derivation unit M212, the derived lost torque TqLS, and a predetermined offset value ΔTq. For example, the deviation threshold derivation unit M23 derives the deviation threshold Δθth such that the absolute value of the product of the proportional gain Gp, which is the gain of the proportional control of the feedback control, and the deviation threshold Δθth is greater than the sum of the lost torque TqLS and the offset value ΔTq. As a result, when the absolute value of the deviation Δθ is greater than or equal to the deviation threshold Δθth, the deviation correction torque TqDC is greater than the sum of the lost torque TqLS and the offset value ΔTq. Therefore, the correction torque TqC, which includes the deviation correction torque TqDC, is greater than the lost torque TqLS. And even when the lost torque TqLS is generated, the output shaft 513a should be able to rotate by the drive of the first electric motor 513. Furthermore, it is preferable that the offset value ΔTq is set to a motor torque of a magnitude that allows the output shaft 513a to begin rotating within the time period indicated by the derivation period of the corrected torque TqC.

[0074] Furthermore, if the absolute value of the deviation Δθ is close to 0 (zero), the rotation angle detection value θmt may be considered substantially equal to the target rotation angle θTr. In this case, if the absolute value of the deviation Δθ falls within the dead zone, even if the absolute value of the deviation Δθ is greater than or equal to the deviation threshold Δθth, the output shaft 513a may not rotate due to the drive of the first electric motor 513. For this reason, if the deviation threshold Δθth derived as described above falls within the dead zone, it is preferable to modify the deviation threshold Δθth so that it is greater than the value defining the dead zone.

[0075] The phase pulse abnormality determination unit M25 determines whether a phase pulse sticking abnormality has occurred in the rotation angle sensor 59 at predetermined determination cycles. The length of this determination cycle is preferably longer than, for example, the derivation cycle of the corrected torque TqC. A phase pulse sticking abnormality is an abnormality in which the signal level of at least one of the phase pulse signals, the A pulse signal SPA and the B pulse signal SPB, does not change even when the output shaft 513a of the first electric motor 513 is rotating. The processing details of the phase pulse abnormality determination unit M25 will be described later with reference to Figure 6.

[0076] If the phase pulse abnormality detection unit M25 determines that a phase pulse sticking abnormality has occurred, it transmits a signal to that effect to the second controller 220. If a phase pulse sticking abnormality occurs, the pressurizing unit 50 cannot adjust the servo pressure Ps. Therefore, when the second processing circuit 221 of the second controller 220 receives the above signal, it controls the wheel pressure of the multiple wheel cylinders 16 by activating the braking actuator 70.

[0077] The Z-pulse abnormality determination unit M27 determines whether or not a Z-pulse sticking abnormality has occurred at predetermined determination cycles. A Z-pulse sticking abnormality is an abnormality in which, when the first electric motor 513 is driven in a direction that increases or decreases the rotation angle detection value θmt, a specific count number Cabz changes, but the Z-pulse PLSZ is not generated. The processing details of the Z-pulse abnormality determination unit M27 will be described later with reference to Figure 7.

[0078] <Processing details of the phase pulse abnormality detection unit> Referring to Figure 6, the processing details of the phase pulse abnormality determination unit M25 will be explained. In step S11, the phase pulse abnormality determination unit M25 determines whether the servo pressure Ps is less than the high-pressure determination value Psth. The criterion for determining whether the servo pressure Ps is high pressure is set as the high-pressure determination value Psth.

[0079] Here, if the servo pressure Ps is high, the motor torque Tq of the first electric motor 513 is also high. If the motor torque Tq is excessively high, the protective control of the first electric motor 513 may intervene. When protective control is executed, motor control that would further increase the servo pressure Ps is not performed, and the rotation angle of the first electric motor 513 may be maintained. If the rotation angle is maintained, the signal levels of the A pulse signal SPA and the B pulse signal SPB do not change even if a phase pulse sticking abnormality does not occur. Therefore, a high-voltage judgment value Psth is set to suppress the occurrence of misjudgments.

[0080] The servo pressure Ps is correlated with the pressing force, which is the force that presses the rotating body 17 of the friction brake 15 against the friction part 18. Therefore, if the servo pressure Ps is greater than or equal to the high-pressure threshold Psth, the pressing force can be considered to be greater than or equal to the pressing threshold. On the other hand, if the servo pressure Ps is less than the high-pressure threshold Psth, the pressing force can be considered to be less than the pressing threshold.

[0081] In step S11, if the servo pressure Ps is less than the high-pressure judgment value Psth (S11: YES), the phase pulse abnormality determination unit M25 can determine that the pressing force is less than the pressing force judgment value. Therefore, the phase pulse abnormality determination unit M25 proceeds to step S13. On the other hand, if the servo pressure Ps is equal to or greater than the high-pressure judgment value Psth (S11: NO), the phase pulse abnormality determination unit M25 can determine that the pressing force is equal to or greater than the pressing force judgment value. Therefore, the phase pulse abnormality determination unit M25 terminates the series of processes shown in Figure 6. In other words, the phase pulse abnormality determination unit M25 does not determine whether or not a phase pulse sticking abnormality has occurred.

[0082] In step S13, the phase pulse abnormality determination unit M25 determines whether the absolute value of the deviation Δθ is greater than or equal to the deviation threshold Δθth. If the absolute value of the deviation Δθ is greater than or equal to the deviation threshold Δθth, it can be considered that the first electric motor 513 is capable of rotating the output shaft 513a even when lost torque TqLS is generated. On the other hand, if the absolute value of the deviation Δθ is less than the deviation threshold Δθth, it can be considered that the rotation of the output shaft 513a driven by the first electric motor 513 may be hindered by lost torque TqLS.

[0083] In step S13, if the absolute value of the deviation Δθ is greater than or equal to the deviation threshold Δθth (S13: YES), the phase pulse abnormality determination unit M25 proceeds to step S17. On the other hand, if the absolute value of the deviation Δθ is less than the deviation threshold Δθth (S13: NO), the phase pulse abnormality determination unit M25 terminates the series of processes shown in Figure 6. In other words, the phase pulse abnormality determination unit M25 does not determine whether or not a phase pulse sticking abnormality has occurred.

[0084] In step S17, the phase pulse abnormality determination unit M25 determines whether the signal level of at least one of the phase pulse signals, A pulse signal SPA and B pulse signal SPB, is maintained. If the signal level of at least one of the phase pulse signals is maintained (S17: YES), the phase pulse abnormality determination unit M25 proceeds to step S19. On the other hand, if the signal levels of A pulse signal SPA and B pulse signal SPB have changed (S17: NO), the phase pulse abnormality determination unit M25 proceeds to step S21. That is, if A pulse PLSA and B pulse PLSB are generated by the rotation angle sensor 59 in conjunction with the driving of the first electric motor 513, the phase pulse abnormality determination unit M25 proceeds to step S21.

[0085] In step S19, the phase pulse abnormality determination unit M25 updates the duration TM of the state in which the signal level of at least one of the A pulse signal SPA and the B pulse signal SPB is held. Then, the phase pulse abnormality determination unit M25 transfers the process to step S23.

[0086] In step S21, the phase pulse abnormality determination unit M25 resets the above-mentioned duration TM to 0 (zero). Then, the phase pulse abnormality determination unit M25 temporarily ends the series of processes shown in FIG. 6.

[0087] In step S23, the phase pulse abnormality determination unit M25 determines whether the duration TM updated in step S19 exceeds the abnormality determination time TMth. For example, a time longer than the determination cycle time, which is the length of the time of the execution cycle of the series of processes shown in FIG. 6, is set as the abnormality determination time TMth. The abnormality determination time TMth may be fixed at a preset predetermined time or may be variable according to the change speed of the target rotation angle θTr or the like. If the duration TM does not exceed the abnormality determination time TMth (S23: NO), the phase pulse abnormality determination unit M25 temporarily ends the series of processes shown in FIG. 6. On the other hand, if the duration TM exceeds the abnormality determination time TMth (S23: YES), the phase pulse abnormality determination unit M25 transfers the process to step S25.

[0088] In step S25, the phase pulse abnormality determination unit M25 determines that a phase pulse sticking abnormality has occurred in the rotation angle sensor 59. Then, the phase pulse abnormality determination unit M25 temporarily ends the series of processes shown in FIG. 6.

[0089] <Processing content of Z pulse abnormality determination unit> Referring to FIG. 7, the processing content of the Z pulse abnormality determination unit M27 will be described. In step S51, the Z-pulse abnormality determination unit M27 determines whether the phase pulse abnormality determination unit M25 has determined that a phase pulse sticking abnormality has occurred. If the phase pulse abnormality determination unit M25 has determined that a phase pulse sticking abnormality has occurred (S51: YES), the Z-pulse abnormality determination unit M27 terminates the series of processes shown in Figure 7. On the other hand, if the phase pulse abnormality determination unit M25 has determined that a phase pulse sticking abnormality has not occurred (S51: NO), the Z-pulse abnormality determination unit M27 proceeds to step S53. If a phase pulse sticking abnormality has not occurred, the specific count Cabz changes as the first electric motor 513 is driven, so the Z-pulse abnormality determination unit M27 proceeds to step S53. As described above, the specific count Cabz is a counter used to determine whether or not a Z-pulse sticking abnormality has occurred.

[0090] In step S53, the Z pulse anomaly determination unit M27 acquires the current specific count number Cabz. As mentioned above, when a Z-pulse sticking abnormality occurs, unlike the count Cab, the specific count Cabz is not reset to 0 (zero) or the specified count Cabth. Therefore, if the rotation angle detection value θmt continues to increase, the specific count Cabz will continue to increase even if it exceeds the specified count Cabth. On the other hand, if the rotation angle detection value θmt continues to decrease, the specific count Cabz will continue to decrease even if it falls below 0 (zero). In other words, even if the specific count Cabz becomes a negative value, the absolute value of the specific count Cabz will continue to increase.

[0091] In the next step S55, the Z-pulse abnormality determination unit M27 determines whether the absolute value of the current specific count Cabz is greater than the abnormality determination count Cabzth. The abnormality determination count Cabzth is the count corresponding to N rotations of the output shaft 513a. "N" is a positive number of 1 or more. Preferably, "N" is 2 or more. If the absolute value of the specific count Cabz is greater than the abnormality determination count Cabzth (S55: YES), the Z-pulse abnormality determination unit M27 proceeds to step S59. On the other hand, if the absolute value of the specific count Cabz is less than or equal to the abnormality determination count Cabzth (S55: NO), the Z-pulse abnormality determination unit M27 terminates the series of processes shown in Figure 7.

[0092] In step S59, the Z-pulse abnormality determination unit M27 determines that a Z-pulse sticking abnormality has occurred. The Z-pulse abnormality determination unit M27 then terminates the series of processes shown in Figure 7.

[0093] <Operation and Effects of This Embodiment> Referring to Figure 8, the operation and effects of this embodiment will be explained. Figure 8 illustrates the changes in servo pressure Ps, target rotation angle θTr, rotation angle detection value θmt, and the determination of whether or not a phase pulse sticking abnormality has occurred when the servo pressure Ps is increased.

[0094] (1) As shown by the dashed line in Figure 8(a), when the target servo pressure PsTr increases from timing t11, the target rotation angle θTr begins to increase as shown in Figure 8(b). The first electric motor 513 is then driven to correct the discrepancy between the target rotation angle θTr and the detected rotation angle θmt. As a result, the detected rotation angle θmt increases. Consequently, as shown by the solid line in Figure 8(a), brake fluid is discharged from the electric cylinder 51 in conjunction with the driving of the first electric motor 513, causing the servo pressure Ps to increase.

[0095] In the example shown in Figure 8, after timing t12, while the target servo pressure PsTr is increasing, the rotation angle sensor 59 stops generating A pulse PLSA and B pulse PLSB. As a result, the count Cab is retained, and therefore the rotation angle detection value θmt is retained.

[0096] At timing t13 in that state, the absolute value of the deviation Δθ between the target rotation angle θTr and the detected rotation angle θmt becomes greater than or equal to the deviation threshold Δθth. From this point onward, the duration TM of the state in which the signal level of the phase pulse signal does not change, even though the deviation correction torque TqDC is greater than the lost torque TqLS, that is, the correction torque TqC including the deviation correction torque TqDC is greater than the lost torque TqLS, is measured. Then, at timing t14, if this duration TM exceeds the abnormality determination time TMth, the first processing circuit 211 determines that a phase pulse sticking abnormality has occurred, as shown in Figure 8(c). Therefore, the first processing circuit 211 can detect that a phase pulse sticking abnormality has occurred at the rotation angle sensor 59.

[0097] (2) The deviation threshold Δθth is derived such that the value increases as the lost torque TqLS shown in Figure 5 increases. If the rotation angle sensor 59 is functioning correctly, the first electric motor 513 should be driven to correct the discrepancy between the target rotation angle θTr and the detected rotation angle θmt if the absolute value of the deviation Δθ is greater than the deviation threshold Δθth. Therefore, if the signal level of the phase pulse signal does not change despite the absolute value of the deviation Δθ being greater than the deviation threshold Δθth, it is possible that a phase pulse sticking abnormality has occurred.

[0098] Therefore, the first processing circuit 211 determines that a phase pulse sticking abnormality has occurred if the signal level of the phase pulse signal remains maintained even after exceeding the abnormality determination time TMth, despite the absolute value of the deviation Δθ being greater than the deviation threshold Δθth. As a result, the first processing circuit 211 can accurately determine whether or not a phase pulse sticking abnormality has occurred at the rotation angle sensor 59.

[0099] (3) The first processing circuit 211 determines that a Z pulse sticking abnormality has occurred in the rotation angle sensor 59 when no phase pulse sticking abnormality has occurred, the rotation angle detection value θmt is increasing or decreasing, and the absolute value of a specific count Cabz exceeds the abnormality determination count Cabzth. In other words, the first processing circuit 211 can determine whether or not a Z pulse sticking abnormality has occurred in the rotation angle sensor 59.

[0100] <Example of changes> The above embodiment can be implemented with the following modifications. The above embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0101] The first processing circuit 211, i.e., the Z pulse abnormality determination unit M27, may perform a different process from the one described in the above embodiment if it can determine that a Z pulse sticking abnormality has occurred. For example, the Z pulse abnormality determination unit M27 may determine that a Z pulse sticking abnormality has occurred when, under the circumstances where no phase pulse sticking abnormality has occurred and the rotation angle detection value θmt continues to increase, the duration TM1 of the state in which the signal level of the Z pulse signal is maintained exceeds the Z pulse abnormality determination time TM1th. Alternatively, the Z pulse abnormality determination unit M27 may determine that a Z pulse sticking abnormality has occurred when, under the circumstances where no phase pulse sticking abnormality has occurred and the rotation angle detection value θmt continues to decrease, the duration TM1 of the state in which the signal level of the Z pulse signal is maintained exceeds the Z pulse abnormality determination time TM1th. The generation period of the Z pulse PLSZ is longer than the generation period of the A pulse PLSA and the B pulse PLSB. Therefore, it is preferable that the Z pulse abnormality determination time TM1th be set to a time longer than the above abnormality determination time TMth.

[0102] The first processing circuit 211 does not need to determine whether or not a Z-pulse sticking abnormality has occurred. In other words, the first processing circuit 211 does not need to have the function of a Z-pulse abnormality determination unit M27.

[0103] The first processing circuit 211, i.e., the deviation threshold derivation unit M23, may derive the deviation threshold Δθth without considering the offset value ΔTq. If the feedback control for deriving the corrected torque TqC includes differential control, the first processing circuit 211, i.e., the deviation threshold derivation unit M23, may also derive the deviation threshold Δθth by considering the differential gain, which is the gain of the differential control.

[0104] If the feedback control for deriving the corrected torque TqC includes integral control, the first processing circuit 211, i.e., the deviation threshold derivation unit M23, may also derive the deviation threshold Δθth by considering the differential gain, which is the gain of the integral control.

[0105] In the above embodiment, when the deviation threshold Δθth is included in the dead zone, the first processing circuit 211, i.e., the deviation threshold derivation unit M23, corrects the deviation threshold Δθth to a predetermined value whose absolute value is greater than the value defining the dead zone, but it is not limited to this. For example, instead of correcting the deviation threshold Δθth, the first processing circuit 211 may determine whether the signal level of at least one of the phase pulse signals, A pulse signal SPA and B pulse signal SPB, is maintained when the deviation Δθ is not included in the dead zone and the absolute value of the deviation Δθ is greater than or equal to the deviation threshold Δθth.

[0106] The rotation angle sensor 59 can also be a sensor that detects the rotation angle of a rotating member other than the output shaft 513a, as long as it detects the rotation angle of the rotor that rotates in response to the drive of the first electric motor 513. For example, the rotation angle sensor 59 can be a sensor that detects the rotation of the rotating part of the conversion mechanism 514.

[0107] A sensor that outputs phase pulse signals SPA and SPB but does not output a Z pulse signal SPZ may be used as the rotation angle sensor 59. The braking unit may have a different configuration from the pressurizing unit 50 shown in Figure 1, as long as it is a unit that can generate a braking force in the vehicle 10 in accordance with the drive of the electric motor. For example, the braking unit may be an electric braking device disclosed in, for example, "Japanese Patent Application Publication No. 2024-143525".

[0108] The first processing circuit 211 is not limited to one that includes a CPU and ROM and executes software processing. That is, the first processing circuit 211 may have any of the following configurations: (a), (b), and (c).

[0109] (a) The first processing circuit 211 comprises one or more processors that perform various processes according to a computer program. The processor includes a CPU and memory such as RAM and ROM. The memory stores program code or instructions configured to cause the CPU to perform the processes. The memory, i.e., computer-readable media, includes any available media that can be accessed by a general-purpose or dedicated computer.

[0110] (b) The first processing circuit 211 includes one or more dedicated hardware circuits that perform various processes. Examples of dedicated hardware circuits include application-specific integrated circuits, i.e., ASICs or FPGAs. ASIC is an abbreviation for "Application Specific Integrated Circuit". FPGA is an abbreviation for "Field Programmable Gate Array".

[0111] (c) The first processing circuit 211 comprises one or more processors that execute a portion of the various processes according to a computer program, and one or more dedicated hardware circuits that execute the remaining processes of the various processes.

[0112] <Other technological ideas> The technical concepts that can be understood from the above embodiments and modified examples are described below. [Note 1] The deviation threshold derivation unit preferably derives the deviation threshold such that its value increases as the output torque of the electric motor increases.

[0113] [Note 2] The vehicle has a friction brake that generates a braking force that increases with increasing pressure, which is the force that presses the friction part against a rotating body that rotates integrally with the wheel. If the phase pulse abnormality determination unit determines that the pressing force is equal to or greater than the pressing force determination value, it is preferable that it does not determine whether or not the phase pulse sticking abnormality has occurred.

[0114] [Note 3] The friction brake has a wheel cylinder to which brake fluid is supplied, and is configured such that the pressing force can be increased as the hydraulic pressure inside the wheel cylinder increases. Preferably, the braking unit includes an electric cylinder configured such that when the rotation angle of the rotor increases due to the drive of the electric motor, the piston moves forward within the cylinder, causing brake fluid to be discharged from the cylinder through an output port.

[0115] In this specification, the expression "at least one" means "one or more" of the desired options. For example, if there are two options, the expression "at least one" means "only one option" or "both of the two options." As another example, if there are three or more options, the expression "at least one" means "only one option" or "a combination of two or more arbitrary options." [Explanation of Symbols]

[0116] 10... Vehicles 11,12...Wheel 15… Friction brakes 16... Wheel cylinder 17…Rotational body 18...Friction part 50…Pressurizing unit (an example of a braking unit) 51…Electric Cylinder 511...Cylinder 512... Piston 513...First electric motor 513a... Output shaft (an example of a rotor) 516…Output port 59… Rotation angle sensor 100...braking device 210...First controller 211...First processing circuit M17... Rotation angle detection unit M21...Motor control unit M23... Deviation threshold derivation unit M25... Phase pulse anomaly detection unit M27...Z pulse anomaly detection unit

Claims

1. A braking device comprising an electric motor and a rotation angle sensor, and a braking unit that generates a braking force on the vehicle in accordance with the drive of the electric motor, The rotation angle sensor is a sensor that outputs a phase pulse signal including a phase pulse that is generated each time the rotor, which rotates in response to the drive of the electric motor, rotates by a predetermined angle. A rotation angle detection unit acquires a rotation angle detection value, which is the detected rotation angle of the rotor, based on the phase pulse signal output from the rotation angle sensor. A motor control unit controls the electric motor so as to output a torque that includes a correction torque, which is a torque that can eliminate the discrepancy between the target rotation angle and the detected rotation angle, based on feedback control that takes the deviation between the target rotation angle, which is the target value of the rotor's rotation angle, and the detected rotation angle as input. A phase pulse abnormality determination unit determines that a phase pulse sticking abnormality, which is an abnormality in which the phase pulse is not generated, has occurred in the rotation angle sensor, if the absolute value of the deviation is greater than or equal to the deviation threshold, and the state in which the signal level of the phase pulse signal is maintained continues even after exceeding the abnormality determination time. The system includes a deviation threshold derivation unit that derives the deviation threshold such that the corrected torque is greater than the lost torque of the electric motor when the absolute value of the deviation is greater than or equal to the deviation threshold. Braking device.

2. The correction torque is a torque that includes a deviation correction torque which is the product of the gain of the feedback control and the deviation. The deviation threshold derivation unit derives the deviation threshold such that the absolute value of the product of the feedback control gain and the deviation threshold is greater than the sum of the lost torque and a predetermined offset value. The braking device according to claim 1.

3. The rotation angle sensor is a sensor that outputs a Z pulse signal including a Z pulse that is generated each time the rotor rotates once. The count of the edges of the phase pulses included in the phase pulse signal output from the rotation angle sensor is reset to 0 (zero) or the count for one rotation of the rotor based on the change in the Z pulse signal. The Z pulse abnormality determination unit determines that an abnormality has occurred in the rotation angle sensor where the Z pulse is not generated when the electric motor is driven in a direction that increases or decreases the rotation angle of the rotor, under conditions where it has been determined that the aforementioned phase pulse sticking abnormality has not occurred, and the absolute value of the edge count exceeds an abnormality determination count which is the number of counts corresponding to N rotations of the rotor. A braking device according to claim 1 or claim 2.

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