Brake system of vehicle

Abstract

A brake system (100) is provided with an electric cylinder (51) having a servo motor (513), a rotation angle sensor (SE2), and a control unit (81). The rotation angle sensor (SE2) is configured so as to detect a Z pulse generated per rotation of the servo motor (513) and a phase pulse generated per rotation of the servo motor (513) by a predetermined rotation angle. The control unit (81) executes a rotation angle sensor inspection process. In the rotation angle sensor inspection process, the control unit (81) rotates the servo motor (513) so as to retreat the piston (512). The control unit (81) counts the number of phase pulses during a period after the detection of the first Z pulse until the detection of the second Z pulse. The control unit (81) determines that the rotation angle sensor (SE2) is normal when the number of phase pulses is within a predetermined range.

Description

Technical Field

[0001] This invention relates to a braking system for a vehicle equipped with an electric cylinder. Background Technology

[0002] It is known that there are braking devices capable of generating braking force through an electric cylinder, which has a piston that moves according to the drive of an electric motor. For example, Patent Document 1 discloses a braking device that supplies brake fluid to a wheel cylinder through the operation of an electric cylinder.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2023-119255

[0004] The electric cylinder disclosed in Patent Document 1 can be controlled based on the rotation angle of the electric motor. The rotation angle of the electric motor can be detected by a rotation angle sensor.

[0005] When controlling an electric cylinder based on the rotation angle detected by a rotation angle sensor, the following problem exists: if the rotation angle detected by the rotation angle sensor is incorrect, the accuracy of controlling the electric cylinder will be reduced, and the control will be different from the original control. Summary of the Invention

[0006] A braking system for a vehicle designed to solve the aforementioned problems includes an electric cylinder that generates braking force. The electric cylinder comprises: a cylinder; a piston housed within the cylinder; a servo motor; a direct-acting conversion mechanism that converts the rotation of the servo motor into forward / reverse movement of the piston; a rotation angle sensor that detects a rotation angle corresponding to the rotation of the servo motor; and a control unit that controls the servo motor. The electric cylinder is configured such that when the piston is retracted from a predetermined pressurization start position, no hydraulic pressure is generated; when the piston moves forward from the pressurization start position, hydraulic pressure is generated. The rotation angle sensor is configured to detect the Z-pulse generated per revolution of the servo motor and the phase pulse generated per predetermined rotation angle of the servo motor. The control unit is configured to detect the rotation angle of the servo motor by counting the phase pulses detected by the rotation angle sensor. When the vehicle's braking system is activated, the control unit performs a rotation angle sensor check process. This check process confirms whether the rotation angle sensor is functioning properly. As the first check process in the rotation angle sensor check process, with a target rotation speed in the first phase as the target, the servo motor is rotated by supplying current to each phase in a predetermined pattern to cause the piston to retract. The Z-pulse detected during the rotation of the servo motor is designated as the first Z-pulse, and the Z-pulse detected after the first Z-pulse is designated as the second Z-pulse. The number of phase pulses during the period from the detection of the first Z-pulse to the detection of the second Z-pulse is counted, and it is confirmed whether the counted number of phase pulses is within a predetermined range. If the number of phase pulses is within the predetermined range, the rotation angle sensor is determined to be functioning properly.

[0007] According to the present invention, it is possible to inspect the rotation angle sensor. Attached Figure Description

[0008] Figure 1 This is a schematic diagram illustrating one implementation of a vehicle's braking system.

[0009] Figure 2 It is a schematic representation Figure 1 A cross-sectional view of the structure of the electric cylinder in the braking system.

[0010] Figure 3 It is a schematic representation Figure 1 A cross-sectional view of the structure of the electric cylinder in the braking system.

[0011] Figure 4 It means Figure 1 A flowchart illustrating the process of checking the rotation angle sensor in the braking system.

[0012] Figure 5 It means Figure 1A flowchart illustrating the process of checking the rotation angle sensor in the braking system.

[0013] Figure 6 Yes Figure 1 A schematic diagram illustrating the position of the piston in the electric cylinder of the braking system.

[0014] Figure 7 This is an example Figure 1 A timing diagram showing the relationship between the counter value of the phase pulse and the Z pulse when checking the rotation angle sensor in the braking system.

[0015] Figure 8 This is a timing diagram illustrating the braking system of the modified example. Detailed Implementation

[0016] The following is for reference Figures 1 to 7 Braking system 100, which is one embodiment of the braking system of a vehicle, will be described.

[0017] like Figure 1 As shown, the braking system 100 includes an electric cylinder 51. The braking system 100 also includes a control unit 81.

[0018] One example of the braking system 100 includes a braking device 20 and a control device 80. One example of the braking device 20 includes a first braking unit 50 and a second braking unit 23 as braking units. Although details will be described later, the first braking unit 50 includes an electric cylinder 51. The control device 80 is capable of controlling the braking device 20. The control device 80 includes a control unit 81.

[0019] exist Figure 1 The diagram illustrates multiple wheels FL, FR, RL, and RR, which are wheels of a vehicle using braking system 100. The multiple wheels FL, FR, RL, and RR include two front wheels FL and FR, and two rear wheels RL and RR. The vehicle is equipped with a brake operating component 21. The brake operating component 21 can be operated by the driver of the vehicle. An example of the brake operating component 21 is a brake pedal.

[0020] The control unit 81 is one example of a processing circuit in a vehicle. The braking system 100 is not limited to the control unit 81 and may include other processing circuits. Some of the functions implemented by the control unit 81 may also be implemented by other processing circuits. The processing circuits in the vehicle can be connected to each other to transmit and receive information. For example, each processing circuit can be configured to be connected to a vehicle-mounted network. The processing circuits connected to the vehicle-mounted network can communicate with each other via the vehicle-mounted network. Various sensors and other detection systems of the vehicle may also be connected to the vehicle-mounted network.

[0021] <Brake Device>

[0022] The braking device 20 includes braking mechanisms 10 corresponding to wheels FL, FR, RL, and RR respectively. The braking mechanisms 10 can apply frictional braking force to each wheel FL, FR, RL, and RR. The braking device 20 can adjust the frictional braking force applied to wheels FL, FR, RL, and RR by each braking mechanism 10.

[0023] One example of the braking device 20 is a hydraulic braking device. For example, the braking device 20 includes a reservoir 24 for storing brake fluid and a hydraulic generating device 22. An example of the hydraulic generating device 22 is a hydraulic generating device of a so-called brake-by-wire type. The hydraulic generating device 22 can generate hydraulic pressure according to the amount of operation of the braking operating component 21. The hydraulic generating device 22 consists of a main unit 30 and a first braking unit 50. The main unit 30 can supply brake fluid to the second braking unit 23. The first braking unit 50 can supply brake fluid to both the main unit 30 and the second braking unit 23.

[0024] <Brake Mechanism>

[0025] The braking mechanism 10 will be described. The braking mechanism 10 includes a wheel cylinder 11 supplied with brake fluid, a rotating plate 12 that rotates integrally with the wheel, and a friction material 13 that moves relative to the rotating plate 12 in the thickness direction of the rotating plate 12. The braking mechanism 10 is configured such that the higher the hydraulic pressure (WC) Pwc within the wheel cylinder 11, the more forcefully the friction material 13 is pressed against the rotating plate 12. According to the braking mechanism 10, the higher the WC pressure Pwc, the greater the frictional braking force applied to the wheels FL, FR, RL, and RR.

[0026] <Main Device>

[0027] One example of the main unit 30 includes a master cylinder 31, a stroke simulator 32, multiple flow paths 331, 332, and 333 connected to the master cylinder 31, and multiple control valves 341 and 342 for controlling the flow of brake fluid. The stroke simulator 32 is capable of generating a reaction force corresponding to the amount of operation of the brake operating component 21.

[0028] The master cylinder 31 includes a cylinder body 41 and a cylinder head 42. The master cylinder 31 includes a master piston 43 and an input piston 44. The master cylinder 31 includes a master spring 45 that applies force to the master piston 43 and an input spring 46 that applies force to the input piston 44. The master piston 43 and the input piston 44 are movable relative to the cylinder body 41 and the cylinder head 42.

[0029] A more detailed explanation is given of an example of master cylinder 31.

[0030] The main body 41 of the master cylinder 31 has a plate-shaped bottom wall 411 and a first peripheral wall 412 extending from the bottom wall 411 along its axis. The main body 41 also has a second peripheral wall 413 extending from the rear end of the first peripheral wall 412 along its axis, and a first annular wall 414 extending from the rear end of the second peripheral wall 413 toward its axis. Both the first peripheral wall 412 and the second peripheral wall 413 are cylindrical. A hole is formed in the first annular wall 414 for insertion of the rear end of the main piston 43, described later. The inner diameter of the first peripheral wall 412 is smaller than the inner diameter of the second peripheral wall 413.

[0031] Within the cylinder body 41, the main chamber Rm is defined by the bottom wall 411, the first peripheral wall 412, and the main piston 43. Hereinafter, within the main cylinder 31, the direction of movement of the main piston 43 will be... Figure 1 The direction to the left, which decreases the volume of the main chamber Rm, is called "forward." On the other hand, the direction opposite to the forward movement of the main piston 43 is called "rearward." The rearward direction is also the direction that increases the volume of the main chamber Rm.

[0032] Within the cylinder body 41, a first liquid chamber R1 is defined by a second peripheral wall 413 and a main piston 43, and a servo chamber Rs is defined by the second peripheral wall 413, a first annular wall 414, and the main piston 43. A main chamber Rm is formed near the front end of the main cylinder 31. The first liquid chamber R1 is formed rearward compared to the main chamber Rm. The servo chamber Rs is also formed rearward compared to the first liquid chamber R1. Inside the cylinder body 41, the main chamber Rm, the first liquid chamber R1, and the servo chamber Rs are not interconnected. Furthermore, the cross-sectional area of ​​the main chamber Rm is equal to the cross-sectional area of ​​the servo chamber Rs. Here, the cross-sectional area of ​​the servo chamber Rs refers to the cross-sectional area of ​​the servo chamber Rs with the main piston 43 housed within it.

[0033] The cylinder head 42 of the master cylinder 31 has a cylindrical third peripheral wall 421 and a second annular wall 422 extending from the rear end of the third peripheral wall 421 toward its axis. The third peripheral wall 421 is mounted on the first annular wall 414 such that its axis coincides with the second peripheral wall 413 of the cylinder body 41. The second annular wall 422 is provided with a hole for the rear end of the input piston 44, which will be described later, to be inserted.

[0034] Within the cylinder head 42, a second liquid chamber R2 is defined by a third peripheral wall 421, a second annular wall 422, and a first annular wall 414 of the cylinder body 41. In the main cylinder 31, the second liquid chamber R2 is formed at the rear compared to the servo chamber Rs.

[0035] The main piston 43 is housed in the main cylinder 31 in a state of surface contact with the inner circumferential surfaces of the first peripheral wall 412, the second peripheral wall 413, and the first annular wall 414 of the cylinder body 41. Therefore, when the main piston 43 moves axially, it slides against the inner circumferential surfaces of the first peripheral wall 412, the second peripheral wall 413, and the first annular wall 414. The rear end of the main piston 43 protrudes rearward relative to the first annular wall 414 and is located within the second liquid chamber R2. The area of ​​the rear end of the main piston 43 is equal to the cross-sectional area of ​​the first liquid chamber R1. Here, the area of ​​the rear end of the main piston 43 is the area subjected to axial force due to the hydraulic pressure of the second liquid chamber R2. The cross-sectional area of ​​the first liquid chamber R1 is the cross-sectional area of ​​the first liquid chamber R1 with the main piston 43 housed.

[0036] The input piston 44 is housed in the master cylinder 31 in a state of surface contact with the inner circumferential surface of the second annular wall 422 of the cylinder head 42. Therefore, when the input piston 44 moves axially, it slides against the inner circumferential surface of the second annular wall 422. The rear end of the input piston 44 protrudes rearward compared to the second annular wall 422. Furthermore, a brake operating member 21 is connected to the rear end of the input piston 44. Therefore, the input piston 44 moves towards the master piston 43 according to the amount of operation of the brake operating member 21. In addition, a gap is formed between the input piston 44 and the master piston 43 in the second fluid chamber R2.

[0037] The main spring 45 is disposed in the main chamber Rm of the cylinder body 41. The main spring 45 exerts a force on the main piston 43 to push it backward. Therefore, if the main piston 43 moves forward, the main spring 45 is elastically compressed.

[0038] An input spring 46 is disposed in the second fluid chamber R2 of the cylinder head 42. The input spring 46 applies a force to the input piston 44, pushing it backward. Therefore, if the input piston 44 moves forward, the input spring 46 is elastically compressed.

[0039] In the main cylinder 31, the main chamber Rm is connected to the reservoir 24. Specifically, the portion of the main chamber Rm near the rear end is connected to the reservoir 24 via a port formed in the first circumferential wall 412 of the cylinder body 41. Therefore, when the main piston 43 moves from... Figure 1 When the indicated position moves forward, the main chamber Rm is not connected to the reservoir 24. As a result, the hydraulic pressure in the main chamber Rm increases as the main piston 43 moves forward. For example, if the hydraulic pressure in the servo chamber Rs increases, the main piston 43 moves forward via the hydraulic pressure in the servo chamber Rs. Consequently, the hydraulic pressure in the main chamber Rm increases.

[0040] The first flow path 331 connects the main chamber Rm to the second brake unit 23. That is, the first flow path 331 connects a portion of the multiple wheel cylinders 11 to the main chamber Rm. Specifically, the first flow path 331 connects the wheel cylinders 11 used for the front wheels FL and FR to the main chamber Rm. The second flow path 332 connects the first fluid chamber R1 to the second fluid chamber R2. The third flow path 333 connects the fluid reservoir 24 to the second flow path 332.

[0041] 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 between the connection point of the first control valve 341 and the third flow path 333 on the second flow path 332 and the second liquid chamber R2. The second control valve 342 is located on the third flow path 333. When the braking system 100 is in operation, the first control valve 341 is opened and the second control valve 342 is closed.

[0042] The stroke simulator 32 is positioned between the first fluid chamber R1 and the first control valve 341 on the second flow path 332. For example, the stroke simulator 32 has an internal piston that is pushed from the back by a spring. In this case, if the piston inside the stroke simulator 32 displaces against the force of the spring due to the inflow of brake fluid from the second flow path 332, pressure is generated in the brake fluid according to the piston's displacement. (Diagram of the piston omitted). Specifically, with the first control valve 341 open and the second control valve 342 closed, if the input piston 44 moves forward due to the operation of the brake operating member 21, the volume of the second fluid chamber R2 decreases, reducing the volume of the input piston 44 entering the second fluid chamber R2. Consequently, brake fluid flowing from the second fluid chamber R2 to the second flow path 332 flows into the stroke simulator 32. As a result, the stroke simulator 32 generates the same pressure in the second fluid chamber R2 and the first fluid chamber R1 connected by the second flow path 332. When the area of ​​the rear end of the main piston 43 protruding into the second liquid chamber R2 is equal to the cross-sectional area of ​​the first liquid chamber R1, the main piston 43 will not move axially due to the pressure generated in the second liquid chamber R2 and the first liquid chamber R1.

[0043] <First Braking Unit>

[0044] The first braking unit 50 includes an electric cylinder 51 with a servo motor 513 as a power source. The first braking unit 50 can adjust the WC pressure Pwc by means of the electric cylinder 51, which operates according to the drive amount of the servo motor 513. That is, the electric cylinder 51 can generate braking force for the vehicle's wheels FL, FR, RL, and RR.

[0045] An example of the first braking unit 50 will be described.

[0046] The first braking unit 50 includes an electric cylinder 51, a hydraulic adjusting valve 551, and a check valve 552.

[0047] The first braking unit 50 includes a fourth flow path 54 connecting the electric cylinder 51 to the reservoir 24. The first braking unit 50 includes a sixth flow path 58 connecting the second braking unit 23 to the electric cylinder 51. The first braking unit 50 includes a fifth flow path 55 connecting the servo chamber Rs of the master cylinder 31 to the sixth flow path 58.

[0048] Hydraulic regulating valve 551 is located in the fifth flow path 55. Hydraulic regulating valve 551 is a solenoid valve that adjusts the differential pressure between the portion of the fifth flow path 55 closer to the servo chamber Rs and the portion of the fifth flow path 55 closer to the electric cylinder 51. In other words, hydraulic regulating valve 551 can adjust the amount of brake fluid supplied to the servo chamber Rs.

[0049] A check valve 552 is provided in parallel with a hydraulic adjusting valve 551 in the fifth flow path 55. The check valve 552 allows the flow of brake fluid from the servo chamber Rs toward the electric cylinder 51 through the check valve 552. On the other hand, the check valve 552 restricts the flow of brake fluid from the electric cylinder 51 toward the servo chamber Rs through the check valve 552.

[0050] <Electric Cylinder>

[0051] The electric cylinder 51 of the first braking unit 50 is disposed between the fourth flow path 54 and the sixth flow path 58. The fourth flow path 54 is connected to the input port 515 of the electric cylinder 51. The sixth flow path 58 is connected to the output port 516 of the electric cylinder 51. The input port 515 and the output port 516 will be described later.

[0052] Reference Figure 1 , Figure 2 as well as Figure 3 The structure of the electric cylinder 51 will be explained.

[0053] The electric cylinder 51 includes a cylinder 511, a piston 512 enclosed within the cylinder 511, a servo motor 513, and a direct-drive conversion mechanism 514. The piston 512 is slidably disposed within the cylinder 511. The servo motor 513 is the power source for the electric cylinder 51. The direct-drive conversion mechanism 514 converts the rotational motion of the output shaft of the servo motor 513 into the linear motion of the piston 512. That is, the direct-drive conversion mechanism 514 converts the rotation of the servo motor 513 into the forward and backward movement of the piston 512.

[0054] An example of a servo motor 513 is a brushless motor. The servo motor 513 has, for example, a three-phase coil consisting of U-phase, V-phase, and W-phase coils. The servo motor 513 is driven by three-phase AC.

[0055] Inside cylinder 511, a hydraulic chamber Re for brake fluid introduction is defined by the peripheral wall of cylinder 511 and piston 512. The position of piston 512 inside cylinder 511 can be changed by driving servo motor 513. Hereinafter, the direction in which the piston 512 moves, decreasing the volume of hydraulic chamber Re, is referred to as the "forward direction Za". The direction in which the piston 512 moves, opposite to the forward direction Za, is referred to as the "reverse direction Zb". The reverse direction Zb is also the direction in which the piston 512 moves, increasing the volume of hydraulic chamber Re.

[0056] When moving piston 512, control device 80 uses end position EP and pressurization start position OP.

[0057] Figure 2 The electric cylinder 51 is shown with piston 512 in the pressurization start position OP. The pressurization start position OP is the position after piston 512 has moved a predetermined amount Xm from the end position EP in the forward direction Za. The pressurization start position OP is the base point when hydraulic pressure is generated by the electric cylinder 51. Here, the end position EP is the position where piston 512 is moved to the end in the reversing direction Zb.

[0058] like Figure 2 as well as Figure 3 As shown, the electric cylinder 51 includes an elastic body 518. When the piston 512 is at its end position EP, the elastic body 518 applies a force to the piston 512 in the forward direction Za, pushing the piston 512 forward. The elastic body 518 is configured to restrict the piston 512 from moving in the backward direction Zb through contact between the piston 512 and the elastic body 518. For example, as... Figure 2 as well as Figure 3 As shown, the elastomer 518 is configured to contact the rear inner wall 511a of the cylinder 511. For example, the elastomer 518 is configured to contact the end face of the piston 512 in the retraction direction Zb when the piston 512 is in the end position EP.

[0059] An example of the elastic body 518 is a disc spring. Leaf springs, coil springs, etc., can also be used as the elastic body 518. Furthermore, elastic components formed from elastic materials such as elastomeric materials and rubber can also be used as the elastic body 518. Figure 2 as well as Figure 3 In the figure, the elastic body 518 is a disc spring that can deform into a flat plate shape.

[0060] After the piston 512 moves backward in the Zb direction and comes into contact with the elastic body 518, and then moves further backward in the Zb direction, the elastic body 518 undergoes elastic deformation. If the piston 512 moves further backward in the Zb direction while the elastic body 518 is elastically deformed, the limit of elastic deformation is eventually reached. The endpoint position EP is set as the position between the position of the piston 512 where the elastic body 518 begins to elastically deform and the position of the piston 512 where the elastic body 518 has deformed to its limit.

[0061] Figure 3 The electric cylinder 51 is shown in the state where the piston 512 has moved to the final retracted position BE in the retracting direction Zb. The state where the piston 512 has moved to the final retracted position BE in the retracting direction Zb is such that, even with maximum driving force, the piston 512 cannot retract further when moved in the retracting direction Zb. Alternatively, the state where the piston has moved to the final retracted position BE in the retracting direction Zb is such that, mechanically, the piston 512 cannot retract further when moved in the retracting direction Zb.

[0062] exist Figure 3 The example illustrates an electric cylinder 51 in which piston 512 moves backward in the direction Zb from its endpoint position EP, and piston 512 abuts against the rear inner wall 511a of cylinder 511 via elastic body 518. At this point, the disc spring, which is the elastic body 518, deforms to its limit, thus becoming a flat plate. For example, as... Figure 3 As shown, when the piston 512 is in contact with the rear inner wall 511a via the elastic body 518, the end face of the piston 512 in the retraction direction Zb moves to the final retraction position BE in the retraction direction Zb. Furthermore, in a configuration assuming the electric cylinder does not have an elastic body, the state in which the end face of the piston in the retraction direction contacts the rear inner wall corresponds to the state in which the piston moves to its end face in the retraction direction.

[0063] An input port 515 and an output port 516 are formed on the peripheral wall of cylinder 511, serving as ports for connecting the hydraulic chamber Re to the outside. A through hole 517 is formed in piston 512. The through hole 517 is formed at a position that allows the input port 515 to communicate with the hydraulic chamber Re when piston 512 is at its end position EP. Thus, when piston 512 is at its end position EP, the hydraulic chamber Re of cylinder 511 communicates with the fourth flow path 54 via the input port 515 and the through hole 517. That is, the hydraulic chamber Re of cylinder 511 communicates with the reservoir 24 via the input port 515 and the through hole 517. Figure 2 as well as Figure 3As shown, input port 515 is open when piston 512 is between the end position EP and the pressurization start position OP. Electric cylinder 51 is configured to block input port 515 if piston 512 moves forward in the forward direction Za from the pressurization start position OP. After blocking input port 515 by piston 512 in this way, the hydraulic pressure in hydraulic chamber Re increases when piston 512 moves further in the forward direction Za. That is, electric cylinder 51 is configured not to generate hydraulic pressure when piston 512 is retracted from the predetermined pressurization start position OP. Electric cylinder 51 is configured to generate hydraulic pressure when piston 512 moves forward from the pressurization start position OP.

[0064] The output port 516 of cylinder 511 is connected to the second braking unit 23 and the fifth flow path 55 via the sixth flow path 58. The output port 516 is always open regardless of the position of piston 512. Therefore, if piston 512 moves in the forward direction Za when the input port 515 is blocked by piston 512, the brake fluid in hydraulic chamber Re will be discharged from the output port 516 to the outside of cylinder 511.

[0065] In addition, such as Figures 1-3 As shown, the electric cylinder 51 of this embodiment does not have a spring that applies a force to push the piston 512 in the backward direction Zb. However, the electric cylinder 51 may also have a spring that applies a force to push the piston 512 in the backward direction Zb.

[0066] like Figure 1 As shown, the first braking unit 50 includes a release flow path 56 and a release valve 57 disposed in the release flow path 56. The release flow path 56 is a flow path that connects the reservoir 24 to the wheel cylinder 11 by bypassing the electric cylinder 51. The first end of the release flow path 56 is connected to the fourth flow path 54, and the second end of the release flow path 56 is connected to the sixth flow path 58. Specifically, the release flow path 56 connects the reservoir 24 on the fourth flow path 54 to the input port 515 and the output port 516 on the sixth flow path 58 to the second braking unit 23. The release valve 57 is a normally closed solenoid valve. Therefore, the release flow path 56 is blocked when the release valve 57 is not opened.

[0067] <Second Braking Unit>

[0068] An example of the second braking unit 23 will be described.

[0069] The second braking unit 23 is a brake actuator capable of independently adjusting the WC pressure Pwc of each wheel FL, FR, RL, RR.

[0070] like Figure 1As shown, the second braking unit 23 includes a front wheel-side pressure adjustment unit 231 and a rear wheel-side pressure adjustment unit 232. The front wheel-side pressure adjustment unit 231 generates friction braking force on the front wheels FL and FR by adjusting the hydraulic pressure of the wheel cylinders 11 used for the front wheels FL and FR. The rear wheel-side pressure adjustment unit 232 generates friction braking force on the rear wheels RL and RR by adjusting the hydraulic pressure of the wheel cylinders 11 used for the rear wheels RL and RR.

[0071] <Brake Device Detection System>

[0072] like Figure 1 As shown, the detection system of the braking device 20 has multiple sensors. The detection signals from the sensors are input to the control unit 80 of the braking device 20. Figure 1 In the diagram, multiple sensors are shown, including the main hydraulic sensor 351, the input hydraulic sensor 352, the control pressure sensor 353, the stroke sensor SE1, and the rotation angle sensor SE2.

[0073] The main hydraulic sensor 351 detects the hydraulic pressure within the main chamber Rm. For example, the main hydraulic sensor 351 is located in the first flow path 331.

[0074] The input hydraulic sensor 352 detects the hydraulic pressure in the second liquid chamber R2. For example, the input hydraulic sensor 352 is connected to the position between the first control valve 341 on the second flow path 332 and the second liquid chamber R2.

[0075] The control pressure sensor 353 is a pressure sensor that detects the hydraulic pressure of the brake fluid supplied from the electric cylinder 51. For example, the control pressure sensor 353 is located near the output port 516 in the electric cylinder 51. As an example, in Figure 1 The diagram shows a configuration in which a control pressure sensor 353 is connected between the release valve 57 on the release flow path 56 and the output port 516.

[0076] The stroke sensor SE1 detects the amount of operation of the braking operation component 21.

[0077] The rotation angle sensor SE2 detects the rotation angle corresponding to the rotation of the power source of the electric cylinder 51, namely the servo motor 513. The rotation angle sensor SE2 is configured to detect the Z pulse generated by the servo motor 513 for each revolution and the phase pulse generated by the servo motor 513 for each predetermined rotation angle. The control unit 81 can detect the rotation angle of the servo motor 513 by counting the phase pulses detected by the rotation angle sensor SE2.

[0078] An example of the rotation angle sensor SE2 is a three-phase rotary encoder consisting of phases A, B, and Z. The output pulse of phase Z corresponds to the Z pulse. The output pulses of phase A (A pulse) and phase B (B pulse) correspond to the phase pulses. The phases of phases A and B are staggered by a predetermined period. Therefore, the rotation direction of the servo motor 513 is determined based on the sequence of the rising and falling edges of the output pulses of phase A and phase B. The output pulses of phases A and B together generate a predetermined maximum value α during one revolution of the servo motor 513. The predetermined maximum value α is determined according to the specifications of the rotation angle sensor SE2.

[0079] <Control Device>

[0080] The control device 80 is capable of controlling the first braking unit 50 and the second braking unit 23.

[0081] The control unit 81 is a functional unit that controls the first braking unit 50 and the second braking unit 23. The control unit 81 can control the servo motor 513.

[0082] The control device 80 includes a drive circuit 82 for controlling the servo motor 513. The drive circuit 82 is, for example, an inverter circuit that converts direct current to three-phase alternating current and supplies it to the coil of the servo motor 513. The control device 80 supplies a current SG to the servo motor 513 for controlling the servo motor 513 by activating the drive circuit 82.

[0083] If the check start condition is met, the control unit 81 performs a rotation angle sensor check process to confirm whether the rotation angle sensor SE2 is functioning correctly. As an example, the check start condition is set to be met when the vehicle's braking system 100 is activated. The check start condition may be determined to be unmet if the rotation angle sensor check process has been performed. The check start condition may also be determined to be unmet if an abnormality determination or a normality determination (described later) is stored as the result of performing the rotation angle sensor check process.

[0084] The check start condition can also be set to be met when the anomaly judgment stored as a result of the rotation angle sensor check process is reset.

[0085] Here, "rotation angle sensor SE2 normal" means that the rotation angle sensor SE2 is not malfunctioning. "Rotation angle sensor SE2 malfunction" means that the rotation angle sensor SE2 cannot detect pulses according to its specifications. For example, it could be that when the servo motor 513 is rotated, it cannot detect more than one type of pulse.

[0086] [Rotation Angle Sensor Inspection and Handling]

[0087] use Figures 4-6 The inspection and processing of rotation angle sensors are explained.

[0088] Figure 4 The flow of processing performed by the control unit 81 is shown. The control unit 81 can execute this processing routine when the start conditions are met.

[0089] If this processing routine begins, the control unit 81 first starts counting the A / B pulses in step S101. Specifically, each time the control unit 81 detects an A pulse and a B pulse, it updates the A / B counter value Cab to a value that increments by 1. The initial value of the A / B counter value Cab is 0. If the control unit 81 starts counting the A / B pulses, the processing moves to step S102.

[0090] In step S102, the control unit 81 initiates an inspection drive that moves the piston 512 toward the decompression side. Specifically, current is supplied to each phase of the servo motor 513 in a predetermined pattern to move the piston 512 in the backward direction Zb. The inspection drive is performed as a sensorless control. Sensorless control is control that does not use signals from a rotation angle sensor. In the inspection drive, the servo motor 513 rotates at a constant rotational speed. The current value supplied to the servo motor 513 in the inspection drive is a current value that generates a torque greater than the resistance when the piston 512 slides within the cylinder 511 when the servo motor 513 is driven by this current value. If the control unit 81 initiates the inspection drive toward the decompression side, the process moves to step S103.

[0091] In step S103, if the piston 512 reaches the decompression side limit (S103: Yes), the control unit 81 moves the process to step S105. On the other hand, if the piston 512 does not reach the decompression side limit (S103: No), the control unit 81 moves the process to step S111.

[0092] The pressure relief limit is explained.

[0093] For example, if the piston 512 is moved backward in the direction Zb by a specified backward limit distance by checking the drive, it can be determined that the pressure relief limit has been reached.

[0094] For example, if the servo motor 513 is rotated by checking the drive to move the piston by the aforementioned retraction limit distance, it can be determined that the pressure reduction limit has been reached. The rotational speed of the servo motor 513 corresponding to the aforementioned retraction limit distance is set as the first phase target rotational speed. The first phase target rotational speed is, for example, more than two revolutions.

[0095] For example, if a first predetermined time has elapsed after the start of the drive check, it can be determined that the decompression limit has been reached. An example of the first predetermined time is the time required for the piston 512 to move in the retracting direction Zb from the state where its end face in the forward direction Za is at the pressurization start position OP until its end face in the retracting direction Zb reaches the final retracted position BE. The first predetermined time can be a value calculated in advance through experiments, etc.

[0096] In step S111, the control unit 81 performs a determination process. The determination process will be described later. If the determination process ends, the control unit 81 moves the process to step S104. In step S104, if the determination end flag is not turned on (S104: No), the control unit 81 moves the process back to step S103.

[0097] On the other hand, if the determination end flag is turned on (S104: Yes), the control unit 81 moves the processing to step S109. In step S109, the control unit 81 determines that the rotation angle sensor SE2 is normal. Thereafter, the control unit 81 ends the current processing routine. In step S109, the control unit 81 may also store information indicating that the rotation angle sensor SE2 is normal.

[0098] Figure 5 This illustrates the decision-making process performed by the control unit 81. The control unit 81... Figure 4 The processing routine can be started in the processing of step S111 shown and the processing of step S112 described later.

[0099] If this processing routine begins, in step S201, the control unit 81 first determines whether a Z-pulse is detected. If no Z-pulse is detected (S201: No), the control unit 81 terminates the processing routine. On the other hand, if a Z-pulse is detected (S201: Yes), the control unit 81 moves the processing to step S202.

[0100] In step S202, the Z counter value Cz is updated to its value after being incremented by 1. The initial value of the Z counter value Cz is 0. If the control unit 81 updates the Z counter value Cz, the process moves to step S203.

[0101] In step S203, if the Z counter value Cz is less than 2, i.e., the Z counter value Cz is 1 (S203: No), the control unit 81 moves the processing to step S205. In step S205, the control unit 81 resets the A / B counter value Cab to its initial value, i.e., 0. Thereafter, the control unit 81 ends the current processing routine.

[0102] On the other hand, if the Z counter value Cz is 2 or higher in step S203 (S203: Yes), the control unit 81 moves the process to step S204. In step S204, the control unit 81 stores the A / B counter value Cab as the counter storage value Cab′. Then, the process moves to step S206. In step S206, the control unit 81 resets the A / B counter value Cab to its initial value, i.e., 0. Then, the control unit 81 moves the process to step S207.

[0103] In step S207, the control unit 81 determines whether the counter's stored value Cab′ is within a specified range. For example, the control unit 81 makes the determination as follows: If the counter's stored value Cab′ is greater than or equal to "the specified maximum value α - Yab / 2" and less than or equal to "the specified maximum value α + Yab / 2", the control unit 81 determines that the counter's stored value Cab′ is outside the specified range. If the counter's stored value Cab′ is less than "the specified maximum value α - Yab / 2", the control unit 81 determines that the counter's stored value Cab′ is outside the specified range. If the counter's stored value Cab′ is greater than "the specified maximum value α + Yab / 2", the control unit 81 determines that the counter's stored value Cab′ is outside the specified range. Here, "Yab / 2" refers to the allowable deviation. The allowable deviation Yab / 2 can be calculated as a specified proportion relative to the specified maximum value α.

[0104] In step S207, if the counter value Cab′ is outside the specified range (S207: No), the control unit 81 terminates the current processing routine. On the other hand, if the counter value Cab′ is within the specified range (S207: Yes), the control unit 81 moves the processing to step S208.

[0105] In step S208, the control unit 81 turns on the decision end flag. The initial value of the decision end flag is off. If the decision end flag is turned on, the control unit 81 terminates this processing routine.

[0106] Return to Figure 4 In step S105, the control unit 81 resets both the A / B counter value Cab and the Z counter value Cz to 0. Then, the control unit 81 moves the processing to step S106.

[0107] In step S106, the control unit 81 initiates an inspection drive that moves the piston 512 toward the pressurization side. Specifically, current is supplied to each phase of the servo motor 513 in a predetermined pattern to move the piston 512 in the forward direction Za. Similar to the inspection drive toward the depressurization side, the inspection drive toward the pressurization side is performed without a rotation angle sensor. If the control unit 81 initiates the inspection drive toward the pressurization side, the process proceeds to step S107.

[0108] In step S107, if the piston 512 has not reached the pressurization side limit (S107: No), the control unit 81 moves the process to step S112. On the other hand, if the piston 512 has reached the pressurization side limit (S107: Yes), the control unit 81 moves the process to step S110.

[0109] The limits on the pressurized side are explained.

[0110] For example, if the piston 512 is moved a predetermined forward limit distance in the forward direction Za by checking the drive, it can be determined that the pressure side limit has been reached.

[0111] For example, if the servo motor 513 is rotated by a check drive to move the piston to the aforementioned advance limit distance, it can be determined that the pressurization limit has been reached. The rotational speed of the servo motor 513 corresponding to the aforementioned advance limit distance is set as the second phase target speed. The second phase target speed is, for example, more than two revolutions. The higher the second phase target speed, the more Z pulses are output, thus increasing the chance of the counter storing the value Cab′. However, it is preferable to set the upper limit of the second phase target speed based on the relationship between the piston 512 and the pressurization start position OP, as described later.

[0112] For example, if a second predetermined time has elapsed after the start of the drive check, it can be determined that the pressurization limit has been reached. An example of the second predetermined time is the time required for the piston 512 to move from its retracted position BE (end face in the retraction direction Zb) to its forward position OP (end face in the forward direction Za). The second predetermined time can be a value calculated beforehand through experiments, etc.

[0113] In step S112, the control unit 81 performs a determination process. If the determination process ends, the control unit 81 moves the process to step S108. In step S108, if the determination end flag is not turned on (S108: No), the control unit 81 moves the process back to step S107.

[0114] On the other hand, if the determination end flag is on (S108: Yes), the control unit 81 moves the processing to step S109. In step S109, the control unit 81 determines that the rotation angle sensor SE2 is normal. Thereafter, the control unit 81 ends the processing routine.

[0115] In step S110, the control unit 81 determines that the rotation angle sensor SE2 is malfunctioning. Thereafter, the control unit 81 terminates the current processing routine. In step S110, the control unit 81 may also store information indicating that the rotation angle sensor SE2 is malfunctioning.

[0116] If the control unit 81 ends the rotation angle sensor check process, it resets the A / B counter value Cab, the Z counter value Cz, the counter storage value Cab′, and the determination end flag to their initial values.

[0117] <Position of the moving piston during the rotation angle sensor inspection process>

[0118] use Figure 6 The position of the piston 512, which moves as detected by the rotation angle sensor in this embodiment, will be explained. Furthermore, Figures 1-3 as well as Figure 6 This is a schematic illustration; the dimensions of the parts in the diagram do not represent the actual dimensions.

[0119] The distance traveled by piston 512 when it moves between the state where its front end is in the pressurization start position OP and the state where its rear end is in the final retraction position BE is defined as the idle distance Li. Here, the front end of piston 512 is the end face of piston 512 in the forward direction Za, and the rear end of piston 512 is the end face of piston 512 in the retraction direction Zb.

[0120] exist Figure 6 The initial position X0, the first position X1, and the second position X2 are displayed. The initial position X0, the first position X1, and the second position X2 satisfy, for example, the relationship described below.

[0121] The initial position X0 is located between the last retraction position BE and the pressurization start position OP. The initial position X0 is a position that satisfies the following relationship with the first position X1 and the second position X2.

[0122] The first position X1 represents the position of the rear end of the piston 512 after it has moved a first displacement LLb in the backward direction Zb, starting from the initial position X0. The first displacement LLb corresponds to the distance the piston 512 retracts by the target rotational speed of the first phase. That is, the first displacement LLb is equal to the maximum retraction distance. The first position X1 is a position closer to the pressurization start position OP than the final retraction position BE. Preferably, the upper limit of the value of the target rotational speed of the first phase can be set to a value that makes the first position X1 closer to the pressurization start position OP than the final retraction position BE.

[0123] The second position X2 represents the position of the front end of the piston 512 when the piston 512 has moved a second displacement LLA in the forward direction Za from the state where the rear end of the piston 512 is in the first position X1. The second displacement LLA corresponds to the distance the piston 512 advances by the target rotational speed of the second phase. That is, the second displacement LLA is equal to the forward limit distance. The second position X2 is a position closer to the final retraction position BE than the pressurization start position OP. Preferably, the upper limit value that can be set for the target rotational speed of the second phase is a value in which the second position X2 is closer to the final retraction position BE than the pressurization start position OP. As the upper limit value that can be set for the target rotational speed of the second phase, it is more preferable that the second position X2 is a value in which the second position X2 is slightly rearward in the retraction direction Zb than the pressurization start position OP. In addition, the idle distance Li is larger than the second displacement LLA. Although the relationship between the magnitudes of the second displacement LLA and the first displacement LLA can be appropriately set, it is preferable that the second displacement LLA is larger than the first displacement LLA.

[0124] Based on the above, the following conclusions can be drawn. Even if piston 512 moves a first displacement LLb in the backward direction Zb from the initial position X0, the rear end of piston 512 will not reach the final retraction position BE. Even if piston 512 moves a second displacement LLa in the forward direction Za from the first position X1, no hydraulic pressure is generated.

[0125] Furthermore, the second position X2 can also be a position where, if the second displacement LLa is greater than the first displacement LLb, the piston 512 moves from the initial position X0 in the forward direction Za by a distance equal to the second displacement LLa minus the distance equivalent to the first displacement LLb. Therefore, even if the piston 512 moves from the initial position X0 in the forward direction Za by a distance equal to the second displacement LLa minus the distance equivalent to the first displacement LLb, no hydraulic pressure is generated.

[0126] <End Processing>

[0127] When disabling the braking system 100, the control unit 81 may also disabling the braking system 100 after performing a termination process that moves the piston 512 to a preset position. The state in which the braking system 100 is disabling refers to the state in which the control unit 81 is not activated. The state in which the control unit 81 is not activated may also include the state in which the control unit 81 is at rest. As an example, the braking system 100 is disabling when the vehicle's start switch is turned off.

[0128] In the final processing, for example, the control unit 81 may move the piston 512 so that the front end of the piston 512 is aligned with the initial position X0. For example, the control unit 81 may move the piston 512 so that the front end of the piston 512 is between the initial position X0 and the pressurization start position OP.

[0129] When the vehicle's braking system 100 is activated and rotation angle sensor check processing begins, the position of piston 512 after the process ends and it has moved is the same as the position of piston 512 when the rotation angle sensor check processing begins.

[0130] <Correspondence>

[0131] When the Z-counter value Cz is 2 or higher, the latest Z-pulse corresponds to the "second Z-pulse". The Z-pulse detected before the latest Z-pulse corresponds to the "first Z-pulse". That is, the Z-pulse detected after the first Z-pulse is the second Z-pulse. In addition, the counter value Cab′ corresponds to the "number of phase pulses in the period from the detection of the first Z-pulse to the detection of the second Z-pulse".

[0132] Figure 4 The process consisting of steps S101, S102, S103, S111, S104, and S109 in the rotation angle sensor inspection process shown corresponds to the first inspection process. Figure 4 The process consisting of steps S106, S107, S112, S108, S109, and S110 in the rotation angle sensor inspection process shown corresponds to the second inspection process. The second inspection process is performed when the rotation angle sensor SE2 is not determined to be normal even after the first inspection process is executed. The piston 512 reaching the decompression side limit can be considered the starting condition for the second inspection process if the normal determination is not made in the first inspection process.

[0133] <Functions and Effects>

[0134] The function and effects of this implementation method are explained.

[0135] Figure 7 The A / B counter value (Cab) and Z pulse are shown when the rotation angle sensor check process has been performed. As an example, the first check process is illustrated.

[0136] like Figure 7 As shown in (b), the first Z pulse is detected at time t1. The second Z pulse is detected at time t2.

[0137] When the first Z pulse is detected at time t1, such as Figure 7 As shown in (a), the A / B counter value Cab is reset to 0 (S205). Thereafter, the A / B counter value Cab is incremented each time an A pulse and a B pulse are detected. If a second Z pulse is detected at time t2, the A / B counter value Cab at this time is stored as the counter save value Cab′ (S204).

[0138] If the A / B counter value Cab at the time point when the second Z pulse is detected (time t2) is within a specified range including the maximum value α specified based on the specifications of the rotation angle sensor SE2, the determination process ends (S208). As a result, the rotation angle sensor SE2 is determined to be normal (S109). Furthermore, in Figure 7 The display shows the range obtained by adding or subtracting the allowable deviation Yab / 2 based on the specified maximum value α. If the counter's stored value Cab′ is within this range, the rotation angle sensor SE2 can be determined to be normal.

[0139] If the A / B counter value Cab is not within the specified range, the judgment process can be repeatedly performed until the piston 512 reaches the depressurization limit. If the piston 512 reaches the depressurization limit, the process can proceed to the second inspection process. In the second inspection process, the judgment process can also be repeatedly performed until the piston 512 reaches the pressurization limit.

[0140] Thus, according to this embodiment, it is possible to check whether the rotation angle sensor SE2 is functioning properly.

[0141] In the rotation angle sensor inspection process, a sensorless control method is used, where the rotation angle sensor signal is not used in the control, to rotate the servo motor 513. Therefore, there are cases where the rotor of the servo motor 513 does not rotate smoothly. For example, the rotor of the servo motor 513 may oscillate between the forward and reverse directions. Consequently, the number of phase pulses detected per revolution in the rotation angle sensor inspection process may deviate from the predetermined maximum value. Furthermore, depending on the relationship between the timing of the output phase pulses and the operation cycle of the control unit 81, the counter value Cab′ may deviate from the predetermined maximum value α. In this embodiment, a predetermined range including the predetermined maximum value α is used to determine whether the A / B counter value Cab from the detection of the first Z pulse until the detection of the second Z pulse is within the predetermined range. Therefore, deviations in the number of phase pulses are permissible when inspecting the rotation angle sensor SE2.

[0142] However, to confirm whether the rotation angle sensor SE2 is functioning correctly, as described above, it is necessary to output Z-pulses and phase pulses by rotating the servo motor 513. Here, when checking the rotation angle sensor SE2, if the electric cylinder 51 generates hydraulic pressure as the servo motor 513 rotates, a braking force corresponding to the hydraulic pressure will be generated in the vehicle. If braking force is generated when checking the rotation angle sensor SE2, it will be a braking force that does not correspond to the driver's operation, thus raising concerns about giving the driver a sense of incongruity.

[0143] In this respect, according to this embodiment, the rotation angle sensor inspection process can be performed without generating hydraulic pressure.

[0144] For example, in the first inspection process, the servo motor 513 is rotated to move the piston 512 in the backward direction Zb, so no hydraulic pressure is generated. In the first inspection process, the target rotational speed of the first phase is more than two revolutions, so at least two Z pulses are output. Thus, an opportunity is obtained to count the phase pulses between the first Z pulse and the second Z pulse.

[0145] In this embodiment, the first phase target rotational speed is set such that the rear end of the piston 512 does not reach the final retraction position BE when the piston retracts by a first displacement LLb corresponding to the first phase target rotational speed. This prevents the rear end of the piston 512 from reaching the final retraction position BE, thus suppressing excessive stress on the electric cylinder 51.

[0146] In this embodiment, the position of piston 512 at the start of the first inspection process is set such that the rear end of piston 512 does not reach the final retraction position BE when the piston retracts by a first displacement LLb corresponding to the target rotational speed of the first phase. This prevents the rear end of piston 512 from reaching the final retraction position BE, thus suppressing excessive stress on the electric cylinder 51.

[0147] In the second inspection process, the second phase target speed is set such that the front end of piston 512 does not reach the pressurization start position OP when the piston advances by a second displacement LLa corresponding to the second phase target speed. Therefore, hydraulic pressure can be suppressed even when piston 512 moves in the forward direction Za. In the second inspection process, the second phase target speed is more than two revolutions, so at least two Z pulses are output. This provides an opportunity to count the phase pulses between the first and second Z pulses.

[0148] In this embodiment, the idle distance Li is made larger than the second displacement LLa. Therefore, when the second inspection process begins, even if the rear end of the piston 512 reaches the final retraction position BE, the front end of the piston 512, which has advanced through the second inspection process, will not reach the pressurization start position OP. As a result, hydraulic pressure generated during the second inspection process can be suppressed.

[0149] There are cases where, even if the rotation angle sensor SE2 is normal, a normal determination is not performed in the first inspection process. For example, if the rear end of piston 512 reaches the final retraction position BE due to the inspection drive towards the decompression side in the first inspection process, the A / B counter value Cab does not increase after the rear end of piston 512 reaches the final retraction position BE. Therefore, there are cases where the counter value Cab′ is outside the specified range. If an abnormal determination is performed under the above situation, there is a possibility that an abnormal determination is incorrectly made even though the rotation angle sensor SE2 is normal.

[0150] In this respect, according to this embodiment, if a normal determination is not made in the first inspection process, the inspection can continue by moving to the second inspection process. This improves the accuracy of checking whether the rotation angle sensor SE2 is functioning correctly.

[0151] By using the termination process to move piston 512, the position of piston 512 at the start time of the rotation angle sensor inspection process can be set to a predetermined position. Therefore, the rotation angle sensor inspection process can be performed without generating hydraulic pressure.

[0152] (Example of amendment)

[0153] This embodiment can be modified as follows. This embodiment and the following modifications can be combined with each other within the scope of technical inconsistency.

[0154] • In the above embodiment, the range obtained by adding or subtracting the allowable deviation Yab / 2 based on the specified maximum value α is set as the specified range. The specified range does not necessarily have to be the specified maximum value α located in the center. For example, the specified range may also be a value above the specified maximum value α minus the value obtained by reducing the allowable β, and below the specified maximum value α plus the value obtained by increasing the allowable γ (β > γ or γ > β).

[0155] • In the above embodiment, the second inspection process is performed if the decompression limit is reached during the first inspection process. Alternatively, an anomaly determination may be performed if the decompression limit is reached instead.

[0156] • In the above embodiment, if a negative determination is made in step S104, the processing in step S103 is performed again. Alternatively, if a negative determination is made in step S104 and the Z counter value Cz is 2 or higher, the processing can be moved to step S105. That is, if the determination of whether the counter stored value Cab′ is within the specified range is performed and the determination end flag is not turned on, the first check process can be ended and the second check process can be started. Alternatively, if a negative determination is made in step S104 and the Z counter value Cz is 2 or higher, the processing can be moved to step S110. That is, if the determination of whether the counter stored value Cab′ is within the specified range is performed and the determination end flag is not turned on, an anomaly determination can be performed.

[0157] • In the above embodiment, if a negative determination is made in step S108, the processing in step S107 is performed again. Alternatively, if a negative determination is made in step S108 and the Z counter value Cz is 2 or higher, the processing can be moved to step S110. That is, an anomaly determination can be performed if the determination end flag is not turned on as a result of determining whether the counter stored value Cab′ is within a specified range.

[0158] • In the above embodiment, the control device 80 receives the Z pulse and phase pulse signals from the rotation angle sensor SE2 and calculates the A / B counter value Cab. Unlike the above embodiment, even when the A / B counter value Cab is calculated at the rotation angle sensor side and the calculated A / B counter value Cab and the presence or absence of the Z pulse are periodically sent, the first check process and the second check process can be performed in the same way to check whether the rotation angle sensor SE2 is normal.

[0159] More specifically, the rotation angle sensor SE2 calculates the A / B counter value Cab related to the rotation angle. For example, if the A / B counter value Cab is 0 (zero) at the Z-pulse detection position, and the rotation is forward from that position, the A / B counter value Cab increases in accordance with the rotation angle, reaching a predetermined maximum value α immediately before the next Z-pulse. Conversely, if the rotation is backward, the A / B counter value Cab decreases in accordance with the rotation angle, reaching 0 (zero) at the next Z-pulse position. In this case, for example, the A / B counter value Cab reaches a predetermined maximum value α immediately after the Z-pulse detection position, and is 0 (zero) immediately before the next Z-pulse. Furthermore, the rotation angle sensor SE2 communicates at predetermined communication intervals CT. When the rotation angle sensor SE2 is in a communication timing state, it transmits the A / B counter value Cab at that time point, and whether the Z-pulse position has passed during the period from the last communication timing to the current communication timing.

[0160] Figure 8 The image shows the A / B counter values ​​(Cab) before and after the Z-pulse position in a normal rotation angle sensor SE2. Figure 8 In, such as Figure 8 (b) shows the Z-pulse passing positions T1Z and T2Z as the detection positions of the Z-pulse. As the rotation angle sensor SE2 rotates in the forward direction Za during the second inspection process, over time... Figure 8The Z-pulse changes from left to right (from position T1Z to position T2Z). First, at communication timing T11 immediately following the first Z-pulse, a value within the specified error range starting from 0 (zero) at the Z-pulse position is sent as the A / B counter value Cab, and the first Z-pulse has passed. At this time, the control device 80 sets the Z-counter value Cz to 1. The control device 80 can also confirm that the value of the A / B counter value Cab is within the specified error range starting from 0 (zero). The control device 80 saves the A / B counter value Cab as the counter save value Cab′ each time it is sent. When the control device 80 sends the A / B counter value Cab at communication timing T20 immediately preceding the second Z-pulse from the rotation angle sensor SE2, it also saves the A / B counter value Cab as the counter save value Cab′. Furthermore, at communication timing T21, which is immediately following the second Z pulse, the A / B counter value Cab is sent as a value within the specified error range starting from 0 (zero) at the position of the Z pulse, and the condition that the Z pulse has passed is also sent. Therefore, when the control device 80 receives a Z pulse equivalent to the second Z pulse passing from the rotation angle sensor SE2 at communication timing T21, it first sets the Z counter value Cz to 2. Then, before updating the counter stored value Cab′, it determines whether the stored counter stored value Cab′ is within the specified range based on the specified maximum value α and the aforementioned specified error range. Thus, it is possible to determine whether the rotation angle sensor SE2 is functioning properly. After the determination, the control device 80 saves the A / B counter value Cab received from the rotation angle sensor SE2 as the counter stored value Cab′.

[0161] Similarly, as the rotation angle sensor SE2 rotates in the backward direction Zb after passing the first inspection process, over time, from Figure 8The Z-pulse changes from right to left (from position T2Z to position T1Z). First, at communication timing T20, immediately following the first Z-pulse, a value within a specified error range from the maximum value α is transmitted as the A / B counter value Cab, and the first Z-pulse has passed. At this time, the control device 80 sets the Z-counter value Cz to 1. Furthermore, the control device 80 can confirm that the value of the A / B counter value Cab is within the specified error range from the maximum value α. The control device 80 saves the A / B counter value Cab as a counter save value Cab′ each time it receives the A / B counter value Cab. When the control device 80 receives the A / B counter value Cab at communication timing T11, immediately preceding the second Z-pulse, from the rotation angle sensor SE2, it also saves the A / B counter value Cab as a counter save value Cab′. Furthermore, at communication timing T10, which is immediately following the second Z pulse, the control device 80 transmits a value within the error range specified from the maximum value α, representing the A / B counter value Cab, and transmits a value that has passed the Z pulse. Therefore, when the control device 80 receives a Z pulse equivalent to the second pulse from the rotation angle sensor SE2 at communication timing T10, it first sets the Z counter value Cz to 2. Then, before updating the stored counter value Cab′, it determines whether the stored counter value Cab′ is within the specified range based on 0 (zero) and the aforementioned specified error range. Thus, it is possible to determine whether the rotation angle sensor SE2 is functioning correctly. After the determination, the control device 80 stores the A / B counter value Cab received from the rotation angle sensor SE2 as the stored counter value Cab′.

[0162] Furthermore, it is preferable to set the aforementioned error range by taking into account the motor rotation speed and communication interval CT in the first inspection process, or the motor rotation speed and communication interval CT in the second inspection process.

[0163] Specifically, the first communication error Y1 caused by the communication delay can be inferred by calculating the A / B counter value Cab at the time point T1L before the communication interval CT, starting from the Z pulse passing through position T1Z. Alternatively, the second communication error Y2 caused by the communication delay can be inferred by calculating the A / B counter value Cab at the time point T2L before the communication interval CT, starting from the Z pulse passing through position T2Z. The specified error range is then calculated based on the allowable deviation Yab / 2 and the first communication error Y1, as well as the allowable deviation Yab / 2 and the second communication error Y2.

[0164] In the above configuration, for example, the rotation angle sensor SE2 includes a processing circuit that performs the functions described above. Specifically, this processing circuit has the functions of calculating the A / B counter value Cab and sending the A / B counter value Cab and the presence or absence of the Z pulse to the control device 80.

[0165] also, Figure 8 As illustrated below. Figure 8 In (a) and (b), the time elapsed between the aforementioned time point T1L and the aforementioned time point T2L is omitted. Figure 8 In (a), a portion of the shift in the A / B counter value Cab between 0 (zero) and the specified maximum value α is omitted. Figure 8 In (b), with Figure 7 (b) shows a smaller interval between the rising and falling edges in a Z pulse.

[0166] • In the above embodiment, a braking system 100 is illustrated, which includes a braking device 20 consisting of a first braking unit 50 and a second braking unit 23. Even if the braking system is different from the above embodiment, as long as it is configured to generate braking force based on the drive of an electric cylinder, it is possible to use a rotation angle sensor for inspection and processing.

[0167] • The control unit 81 and other processing circuits can be configured as follows: The processing circuit can be configured as a circuit that includes one or more processors that execute various processes according to a computer program. The processing circuit can be configured as a circuit that includes one or more hardware circuits that execute various processes. The processing circuit can be configured as a circuit that combines one or more processors that execute a portion of the various processes with one or more hardware circuits that execute the remaining processes.

[0168] A processor includes processing devices such as a CPU. It also includes memory such as RAM and ROM. Memory stores program code or instructions configured to enable the processing devices to execute processing. Memory, or storage medium, encompasses all available media accessible through a general-purpose or special-purpose computer. Examples of hardware circuits include application-specific integrated circuits (ASICs). Other examples of hardware circuits include FPGAs.

Claims

1. A braking system for a vehicle, comprising an electric cylinder that generates braking force on the vehicle, wherein, The aforementioned electric cylinder comprises: a cylinder; a piston housed within the cylinder; a servo motor; a direct-acting conversion mechanism that converts the rotation of the servo motor into the forward and backward movement of the piston; a rotation angle sensor that detects the rotation angle corresponding to the rotation of the servo motor; and a control unit that controls the servo motor. The electric cylinder described above is configured such that no hydraulic pressure is generated when the piston is in a position retracted from the predetermined pressurization start position, and hydraulic pressure is generated when the piston moves forward from the pressurization start position. The aforementioned rotation angle sensor is configured to detect the Z-pulse generated by the servo motor for each revolution and the phase pulse generated by the servo motor for each predetermined rotation angle. The control unit described above is configured to detect the rotation angle of the servo motor by counting the phase pulses detected by the rotation angle sensor. When the vehicle's braking system is activated, the aforementioned control unit performs a rotation angle sensor check process to confirm whether the rotation angle sensor is functioning properly. As the first inspection process in the aforementioned rotation angle sensor inspection process, with the first phase target rotation speed as the target, the servo motor is rotated by supplying current to each phase of the servo motor in a predetermined pattern to cause the piston to retract. The Z pulse detected during the rotation of the servo motor is designated as the first Z pulse, and the Z pulse detected after the first Z pulse is designated as the second Z pulse. The number of phase pulses during the period from the detection of the first Z pulse to the detection of the second Z pulse is counted, and it is confirmed whether the counted number of phase pulses is within a predetermined range. If the number of phase pulses is within the predetermined range, the rotation angle sensor is determined to be normal.

2. The braking system of the vehicle according to claim 1, wherein, If the control unit fails to determine that the rotation angle sensor is normal even after performing the first check process, it will perform the second check process within the rotation angle sensor check process. In the second inspection process described above, with the second phase target speed as the target, the servo motor is rotated by supplying current to each phase of the servo motor in a predetermined pattern to make the piston move forward. The Z pulse detected during the rotation of the servo motor is designated as the first Z pulse, and the Z pulse detected after the first Z pulse is designated as the second Z pulse. The number of phase pulses during the period from the detection of the first Z pulse to the detection of the second Z pulse is counted, and it is confirmed whether the counted number of phase pulses is within the predetermined range. If the number of phase pulses is within the predetermined range, the rotation angle sensor is determined to be normal.

3. The braking system of the vehicle according to claim 2, wherein, The idling distance is set to be greater than the second displacement. The idling distance is the distance the piston moves from its last retraction position (where it will not retract further) to the pressurization start position. The second displacement is the distance the piston travels by the target rotational speed of the second phase.

Images