Electric cylinder device

Abstract

An electric cylinder device is provided with an electric cylinder (51) and a control device. The electric cylinder (51) is provided with an elastic body (518) that, when the piston (512) is located at the end position (EP), applies a force to the piston (512) so as to press the piston (512) in the forward direction (Za). The control device executes an end-point movement process for moving the piston (512) to an end-point position (EP). The end point movement process is to drive the electric motor (513) so that the rotational speed of the electric motor (513) becomes a target rotational speed, move the piston (512) in the backward direction (Zb), and, when the value of the current flowing through the electric motor (513) increases compared to the determination value, determine that the piston (512) has reached the end point position (EP) and terminate the driving of the electric motor (513). The determination value is a value obtained by increasing the value of current flowing through the electric motor (513) when the rotational speed of the electric motor (513) follows the target rotational speed by an increase amount.

Description

TECHNICAL FIELD

[0001] The present application relates to an electric cylinder device. BACKGROUND

[0002] An electric cylinder in which a piston is moved in a cylinder according to driving of an electric motor is disclosed in Patent Literature 1. In the electric cylinder, a position after the piston is advanced by a prescribed amount after the piston is retracted to a terminal position is set as an origin position which becomes a base point of generation of hydraulic pressure. The terminal position is detected by setting the rotation angle on the most retraction direction side at the time when the time displacement of the rotation angle of the electric motor converges due to the piston abutting against the end on the retraction direction as the rotation angle corresponding to the terminal position.

[0003] Patent Literature 1: Japanese Patent Application Publication No. 2014-19246

[0004] If the driving of the electric motor is continued in a state where the movement of the piston in the retraction direction is restricted due to the piston abutting against the end on the retraction direction in the electric cylinder, there is a case where the rotational torque generated by the electric motor excessively increases.

[0005] If the terminal position is detected by the piston abutting as in Patent Literature 1, the load applied to the electric cylinder increases, so there is a concern that the durability of the components constituting the electric cylinder decreases. SUMMARY

[0006] An electric cylinder device for solving the above-described problem includes a liquid tank that stores a working liquid; an electric cylinder configured to supply the working liquid to a supply target by moving a piston in a cylinder in accordance with driving of an electric motor; and a control device that controls the electric motor, the electric cylinder device supplies the working liquid to the supply target, and the electric cylinder device is characterized in that: the electric cylinder includes a hydraulic chamber that is divided by the cylinder and the piston in the cylinder, an input port that communicates the liquid tank with the hydraulic chamber, and an output port that discharges the working liquid of the hydraulic chamber toward the supply target, a direction in which a volume of the hydraulic chamber is reduced in a moving direction of the piston is set as a forward direction, a direction opposite to the forward direction in the moving direction of the piston is set as a backward direction, the control device uses a home position to drive the electric motor when moving the piston, the home position is a position after the piston moves a prescribed movement amount from a position in which the piston moves to an end portion in the backward direction as a terminal position and moves in the forward direction, the electric cylinder includes an elastic body that exerts a force that presses the piston in the forward direction on the piston when the piston is positioned at the terminal position, the electric cylinder is configured such that the input port is open when the piston is positioned at the home position, and the input port is closed by the piston when the piston moves from the home position in the forward direction, and the hydraulic pressure of the hydraulic chamber increases, the control device performs terminal movement processing that moves the piston to the terminal position in order to set a relative position of the piston with respect to the input port, the terminal movement processing drives the electric motor such that a rotational speed of the electric motor becomes a target rotational speed and moves the piston in the backward direction, and the control device ends the driving of the electric motor when it is determined that the piston reaches the terminal position in a case where a current value that flows through the electric motor increases compared to a determination value, the determination value is a value in which the current value that flows through the electric motor when the rotational speed of the electric motor follows the target rotational speed is set as a reference and is increased by an increase amount compared to the current value.

[0007] According to the above-described configuration, in a case where the end point movement processing is executed, if the electric motor is driven in a manner that the rotational speed follows the target rotational speed to move the piston in the backward direction, the piston comes into contact with the elastic body. If the piston is continuously moved in the backward direction after the piston comes into contact with the elastic body, the torque gradually increases as the elastic body is elastically deformed after the contact of the piston with the elastic body. Therefore, if the piston approaches the end point position, the torque generated by the electric motor, that is, the current value flowing through the electric motor gradually increases. Therefore, in the above-described configuration, the current value flowing through the electric motor when the rotational speed of the electric motor follows the target rotational speed is set as a reference to set a determination value for determining that the piston reaches the end point position. By setting a value obtained by increasing the current value serving as the reference by an increase amount as the determination value, the current value is not easily excessively increased before the movement of the piston in the backward direction ends. Thus, it is possible to suppress an increase in the load applied to the electric cylinder when the piston is moved to the end point position. BRIEF DESCRIPTION OF DRAWINGS

[0008] Figure 1 is a schematic view that shows a brake device according to an embodiment of an electric cylinder device.

[0009] Figure 2 is a cross-sectional view that schematically shows a structure of an electric cylinder possessed by the electric cylinder device of Figure 1

[0010] Figure 3 is a cross-sectional view that schematically shows a structure of an electric cylinder possessed by the electric cylinder device of Figure 1

[0011] Figure 4 is a flowchart that shows a flow of processing executed by a control device possessed by the electric cylinder device of Figure 1

[0012] Figure 5 is a time chart that shows a change in a current value when a piston is moved to an end point position in the electric cylinder device of Figure 1

[0013] Figure 6 is a cross-sectional view that schematically shows a structure of an electric cylinder possessed by the electric cylinder device of Figure 1 DETAILED DESCRIPTION

[0014] Hereinafter, an embodiment of an electric cylinder device will be described with reference to Figures 1-6

[0015] Figure 1 ​​​​​​A brake device 20 of a vehicle is shown as one example of an application of the electric cylinder device. The brake device 20 has a brake portion that can apply a braking force to a wheel of the vehicle. The brake device 20 has a control device 100 that can control the brake portion. One example of the brake device 20 has a first brake portion 50 and a second brake portion 23 as the brake portion. The first brake portion 50 has an electric cylinder 51. The electric cylinder device is composed of the electric cylinder 51 and the control device 100. The electric cylinder device has a reservoir 24.

[0016] In Figure 1 Front wheels FL, FR and rear wheels RL, RR are shown as the wheels of the vehicle. The vehicle has a brake operation member 21. The brake operation member 21 can be operated by a driver of the vehicle. One example of the brake operation member 21 is a brake pedal.

[0017] The control device 100 is one example of a processing circuit provided in the vehicle. The vehicle is not limited to the control device 100, and can have other processing circuits. Part of the functions achieved by the control device 100 can be achieved by other processing circuits. The processing circuits provided in the vehicle are connected to each other so as to be able to transmit and receive information to and from each other. For example, a configuration in which each processing circuit is connected to an in-vehicle network provided in the vehicle can be adopted. Each processing circuit connected to the in-vehicle network can communicate with each other via the in-vehicle network. The in-vehicle network can be connected, for example, to various detection systems provided in the vehicle, such as various sensors.

[0018] < Brake Device >

[0019] The brake device 20 has brake mechanisms corresponding to the wheels FL, FR, RL, RR, respectively. By the brake mechanisms, a frictional braking force can be applied to each of the wheels FL, FR, RL, RR. The frictional braking force applied to each of the wheels FL, FR, RL, RR by each brake mechanism can be adjusted by the brake device 20. In Figure 1 A front wheel brake mechanism 10A corresponding to the front wheels FL, FR among the wheels, and a rear wheel brake mechanism 10B corresponding to the rear wheels RL, RR among the wheels are shown as the brake mechanisms.

[0020] One example of the brake device 20 is a hydraulic brake device. For example, the brake device 20 has a reservoir 24 that stores brake fluid, and a hydraulic pressure generating device 22. One example of the hydraulic pressure generating device 22 is a so-called brake-by-wire hydraulic pressure generating device. The hydraulic pressure generating device 22 can generate hydraulic pressure in accordance with an operation amount of the brake operation member 21. The hydraulic pressure generating device 22 is composed of a master device 30 and the first brake portion 50. The master device 30 can supply brake fluid to the second brake portion 23. The first brake portion 50 can supply brake fluid to the master device 30 and the second brake portion 23.

[0021] < Brake Mechanism >

[0022] The front-wheel brake mechanism 10A and the rear-wheel brake mechanism 10B will be described. The front-wheel brake mechanism 10A includes a wheel cylinder 11 to which brake fluid is supplied, 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 front-wheel brake mechanism 10A is configured so that the higher the hydraulic pressure within the wheel cylinder 11, or WC pressure Pwc, the stronger the friction material 13 is pressed against the rotating plate 12. The rear-wheel brake mechanism 10B, like the front-wheel brake mechanism 10A, comprises the wheel cylinder 11, the rotating plate 12, and the friction material 13. Depending on the brake mechanism, the higher the WC pressure Pwc, the greater the friction braking force applied to the wheels FL, FR, RL, and RR.

[0023] Main unit

[0024] An example of the master device 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 can generate a reaction force corresponding to the amount of operation of the brake operating member 21.

[0025] The master cylinder 31 includes a cylinder body 41 and a cylinder head 42. The master cylinder 31 includes a primary piston 43 and an input piston 44. The master cylinder 31 includes a main spring 45 that applies a force to press the primary piston 43, and an input spring 46 that applies a force to press the input piston 44. The primary piston 43 and the input piston 44 are movable relative to the cylinder body 41 and the cylinder head 42.

[0026] An example of the master cylinder 31 will be described in more detail.

[0027] The cylinder body 41 of the master cylinder 31 has a plate-shaped bottom wall 411 and a first circumferential wall 412 extending from the bottom wall 411 along the axis of the bottom wall 411. Furthermore, the cylinder body 41 has a second circumferential wall 413 extending from the rear end of the first circumferential wall 412 along the axis of the first circumferential wall 412, and a first annular wall 414 extending from the rear end of the second circumferential wall 413 toward the axis of the second circumferential wall 413. The first and second circumferential walls 412, 413 are each cylindrical. A hole is formed in the first annular wall 414 for inserting the rear end of the master piston 43, described later. The inner diameter of the first circumferential wall 412 is smaller than that of the second circumferential wall 413.

[0028] In the cylinder body 41, the main chamber Rm is divided by the bottom wall 411, the first peripheral wall 412 and the main piston 43. Figure 1 The left direction in the figure, that is, the direction in which the volume of the primary chamber Rm decreases, is referred to as "forward". On the other hand, the direction opposite to the forward direction of movement of the primary piston 43 is referred to as "rearward". The rearward direction is also the direction in which the volume of the primary chamber Rm increases.

[0029] In the cylinder main body 41, the first liquid chamber Rl is divided by the second peripheral wall 413 and the main piston 43, and the servo chamber Rs is divided by the second peripheral wall 413 and the first annular wall 414 and the main piston 43. The main chamber Rm is formed at a position close to the front end of the main cylinder 31. The first liquid chamber Rl is formed at the rear compared to the main chamber Rm. The servo chamber Rs is formed at the rear compared to the first liquid chamber Rl. In the inside of the cylinder main body 41, the main chamber Rm, the first liquid chamber Rl, and the servo chamber Rs are not connected to each other. In addition, 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 in a state where the main piston 43 is accommodated.

[0030] The cylinder cover 42 of the main cylinder 31 has a third peripheral wall 421 in a cylindrical shape and a second annular wall 422 extending from the rear end of the third peripheral wall 421 toward the axis of the third peripheral wall 421. The third peripheral wall 421 is attached to the first annular wall 414 in such a manner that the axis coincides with the second peripheral wall 413 of the cylinder main body 41. In the second annular wall 422, a hole into which the rear end portion of the input piston 44 described later is inserted is provided.

[0031] In the cylinder cover 42, the second liquid chamber R2 is divided by the third peripheral wall 421, the second annular wall 422, and the first annular wall 414 of the cylinder main body 41. In the main cylinder 31, the second liquid chamber R2 is formed at the rear compared to the servo chamber Rs.

[0032] The main piston 43 is accommodated in the main cylinder 31 in a state of contacting the inner peripheral surface of the first peripheral wall 412 of the cylinder main body 41, the inner peripheral surface of the second peripheral wall 413, and the inner peripheral surface of the first annular wall 414. Therefore, in the case where the main piston 43 moves in the axial direction, the main piston 43 slides with the inner peripheral surface of the first peripheral wall 412, the inner peripheral surface of the second peripheral wall 413, and the inner peripheral surface of the first annular wall 414. The rear end portion of the main piston 43 protrudes toward the rear compared to the first annular wall 414 and is located in the second liquid chamber R2. The area of the rear end portion of the main piston 43 is equal to the cross-sectional area of the first liquid chamber Rl. Here, the area of the rear end portion of the main piston 43 is the area subjected to force in the axial direction due to the hydraulic pressure of the second liquid chamber R2. The cross-sectional area of the first liquid chamber Rl refers to the cross-sectional area of the first liquid chamber Rl in a state where the main piston 43 is accommodated.

[0033] The input piston 44 is housed in the master cylinder 31 in a state of being in contact with the inner circumferential surface of the second annular wall 422 of the cylinder cover 42. Therefore, in a case where the input piston 44 moves in the axial direction, the input piston 44 slides with the inner circumferential surface of the second annular wall 422. The rear end portion of the input piston 44 protrudes rearward as compared with the second annular wall 422. Also, the brake operation member 21 is connected to the rear end portion of the input piston 44. Therefore, the input piston 44 moves in a direction approaching the master piston 43 in accordance with the operation amount of the brake operation member 21. In addition, a gap is formed between the input piston 44 and the master piston 43 in the second fluid chamber R2.

[0034] The master spring 45 is disposed in the master chamber Rm of the cylinder main body 41. The master spring 45 exerts a force that presses the master piston 43 rearward on the master piston 43. Therefore, if the master piston 43 moves forward, the master spring 45 is elastically compressed.

[0035] The input spring 46 is disposed in the second fluid chamber R2 of the cylinder cover 42. The input spring 46 exerts a force that presses the input piston 44 rearward on the input piston 44. Therefore, if the input piston 44 moves forward, the input spring 46 is elastically compressed.

[0036] In the master cylinder 31, the master chamber Rm is connected to the reservoir 24. Specifically, a portion of the master chamber Rm near the rear end is connected to the reservoir 24 via a port formed in the first peripheral wall 412 of the cylinder main body 41. Therefore, in a case where the master piston 43 moves forward from the initial position shown in FIG. 1, the master chamber Rm is not connected to the reservoir 24. As a result, as the master piston 43 moves forward, the hydraulic pressure of the master chamber Rm increases. For example, if the hydraulic pressure of the servo chamber Rs increases, the master piston 43 moves forward by the hydraulic pressure of the servo chamber Rs. Thus, the hydraulic pressure of the master chamber Rm increases. Figure 1 The first flow path 331 connects the master chamber Rm and the second brake portion 23. That is, the first flow path 331 is a flow path that connects a portion of the plurality of wheel cylinders 11 and the master chamber Rm. Specifically, the first flow path 331 connects the wheel cylinders 11 for the front wheels FL, FR and the master chamber Rm. The second flow path 332 connects the first fluid chamber Rl and the second fluid chamber R2. The third flow path 333 connects the reservoir 24 and the second flow path 332.

[0037] The first control valve 341 is a normally closed electromagnetic valve. The second control valve 342 is a normally open electromagnetic valve. The first control valve 341 is disposed on the second flow path 332 between the connection point with the third flow path 333 and the second fluid chamber R2. The second control valve 342 is provided to the third flow path 333. In a case where the control device 100 of the brake device 20 is operating, the first control valve 341 is opened and the second control valve 342 is closed.

[0038]

[0039] ​The stroke simulator 32 is provided between the first liquid chamber R1 on the second flow path 332 and the first control valve 341. For example, the stroke simulator 32 has a piston that is pressed from the back by a force of a spring inside. In this case, if the piston inside the stroke simulator 32 is displaced against the force of the spring due to the brake fluid flowing in from the second flow path 332, the brake fluid is pressurized according to the displacement of the piston. The illustration of the piston is omitted. Specifically, in a state in which the first control valve 341 is open and the second control valve 342 is closed, if the input piston 44 is moved forward by the operation of the brake operation member 21, the volume of the second liquid chamber R2 decreases by the amount of the volume of the input piston 44 that enters the second liquid chamber R2. Thus, the brake fluid that flows out of the second liquid chamber R2 to the second flow path 332 flows into the stroke simulator 32. As a result, the same pressure is generated in the second liquid chamber R2 and the first liquid chamber R1 through the stroke simulator 32 that connects the second liquid chamber R2 and the first liquid chamber R1 through the second flow path 332. In a case in which the area of the rear end portion of the master cylinder piston 43 that protrudes into the second liquid chamber R2 is equal to the cross-sectional area of the first liquid chamber R1, the master cylinder piston 43 does not move in the axial direction due to the pressure in a state in which the same pressure is generated in the second liquid chamber R2 and the first liquid chamber R1.

[0040] <First brake portion>

[0041] The first brake portion 50 includes the electric cylinder 51 that has the first electric motor 513 as a power source. The first brake portion 50 is capable of adjusting the WC pressure Pwc by the electric cylinder 51 that operates according to the amount of driving of the first electric motor 513. That is, the first brake portion 50 is capable of generating a braking force to the wheels FL, FR, RL, and RR of the vehicle.

[0042] One example of the first brake portion 50 will be described.

[0043] The first brake portion 50 includes the electric cylinder 51, the hydraulic pressure adjustment valve 551, and the check valve 552.

[0044] The first brake portion 50 includes the fourth flow path 54 that connects the electric cylinder 51 and the reservoir 24. The first brake portion 50 includes the sixth flow path 58 that connects the second brake portion 23 and the electric cylinder 51. The first brake portion 50 includes the fifth flow path 55 that connects the servo chamber Rs of the master cylinder 31 and the sixth flow path 58.

[0045] The hydraulic pressure adjustment valve 551 is provided to the fifth flow path 55. The hydraulic pressure adjustment valve 551 is a solenoid valve that adjusts the differential pressure of the portion of the fifth flow path 55 on the servo chamber Rs side compared to the hydraulic pressure adjustment valve 551 and the portion of the fifth flow path 55 on the electric cylinder 51 side compared to the hydraulic pressure adjustment valve 551. That is, the hydraulic pressure adjustment valve 551 is capable of adjusting the amount of supply of the brake fluid to the servo chamber Rs.

[0046] The check valve 552 is provided in parallel with the 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.

[0047]

[0048] The electric cylinder 51 provided in the first brake portion 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.

[0049] Reference Figure 1 Figure 2 and Figure 3 The configuration of the electric cylinder 51 will be described.

[0050] The electric cylinder 51 includes a cylinder 511, a piston 512, a first electric motor 513, and a conversion mechanism 514. The piston 512 is disposed in the cylinder 511 in a slidable manner. The first electric motor 513 is a power source of the electric cylinder 51. The conversion mechanism 514 converts the rotational motion of an output shaft of the first electric motor 513 into the linear motion of the piston 512.

[0051] Inside the cylinder 511, a hydraulic chamber Re into which brake fluid is introduced is partitioned by the peripheral wall of the cylinder 511 and the piston 512. The position of the piston 512 inside the cylinder 511 can be changed by driving the first electric motor 513. Hereinafter, the direction in which the volume of the hydraulic chamber Re is reduced among the moving directions of the piston 512 will be referred to as the "forward direction Za". The direction opposite to the forward direction Za among the moving directions of the piston 512 will be referred to as the "backward direction Zb". The backward direction Zb is also the direction in which the volume of the hydraulic chamber Re is increased among the moving directions of the piston 512.

[0052] When the piston 512 is moved, the control device 100 uses the end point position EP and the origin position OP. Figure 2 The electric cylinder 51 in which the piston 512 is located at the end point position EP. The end point position EP is a position at which the piston 512 is moved to the end portion in the backward direction Zb. Figure 3 The electric cylinder 51 in which the piston 512 is located at the origin position OP. The origin position OP is a position after the piston 512 is moved from the end point position EP in the forward direction Za by a predetermined movement amount Xm. The origin position OP becomes a base point when the hydraulic pressure is generated by the electric cylinder 51.

[0053] As Figure 2 and Figure 3 ​​As shown, the electric cylinder 51 is provided with an elastic body 518. The elastic body 518 exerts a force that presses the piston 512 in the advancing direction Za against the piston 512 in a case where the piston 512 is located at the end position EP. The elastic body 518 is configured to restrict the piston 512 from moving in the retreating direction Zb by contact of the piston 512 against the elastic body 518. For example, as shown in Figure 2 and Figure 3 As shown, the elastic body 518 is configured to be in contact with the rear inner wall 511a of the cylinder 511. For example, as shown in Figure 2 As shown, the elastic body 518 is configured to be in contact with an end surface of the piston 512 in the retreating direction Zb of the piston 512 located at the end position EP.

[0054] One example of the elastic body 518 is a disc spring. As the elastic body 518, a leaf spring, a coil spring, or the like can also be used. As the elastic body 518, an elastic member shaped from an elastic material such as a high-elasticity body or rubber can also be used. Further, in Figure 2 , Figure 3 , Figure 6 In the above, a disc spring that can be deformed to a flat plate shape is illustrated as the elastic body 518.

[0055] In a case where the piston 512 moves in the retreating direction Zb after the piston 512 moves in the retreating direction Zb and comes into contact with the elastic body 518, the elastic body 518 is elastically deformed. If the piston 512 is further moved in the retreating direction Zb while the elastic body 518 is elastically deformed, the elastic body 518 eventually reaches a limit of elastic deformation. The end position EP is set to a position between a position of the piston 512 at which the elastic body 518 starts to be elastically deformed and a position of the piston 512 at which the elastic body 518 is deformed to the limit. Figure 2 The elastic body 518 illustrated as an example shows a state in which elastic deformation starts.

[0056] The input port 515 and the output port 516 are formed in the peripheral wall of the cylinder 511 as ports that connect the hydraulic chamber Re with the outside. The through-hole 517 is formed in the piston 512. The through-hole 517 is formed at a position at which the input port 515 and the hydraulic chamber Re can be communicated with each other when the piston 512 is located at the end position EP. Thus, in a case where the piston 512 is located at the end position EP, the hydraulic chamber Re of the cylinder 511 is communicated with the fourth flow path 54 via the input port 515 and the through-hole 517. That is, the hydraulic chamber Re of the cylinder 511 is communicated with the reservoir 24 via the input port 515 and the through-hole 517. As shown in Figure 2 and Figure 3As shown, the input port 515 is open when the piston 512 is between the end position EP and the origin position OP. The electric cylinder 51 is configured so that when the piston 512 moves from the origin position OP in the forward direction Za, the input port 515 is closed by the piston 512. After the input port 515 is closed by the piston 512, if the piston 512 moves further in the forward direction Za, the hydraulic pressure in the hydraulic chamber Re increases.

[0057] The output port 516 of the cylinder 511 is connected to the second brake component 23 and the fifth flow path 55 via the sixth flow path 58. The output port 516 remains open regardless of the position of the piston 512. Therefore, when the input port 515 is closed by the piston 512 and the piston 512 moves in the forward direction Za, the brake fluid in the hydraulic chamber Re is discharged from the cylinder 511 through the output port 516.

[0058] In addition, if Figures 1-3 As shown, the electric cylinder 51 included in the brake device 20 does not include a spring that applies a force to press the piston 512 in the backward direction Zb. The electric cylinder 51 may include a spring that applies a force to press the piston 512 in the backward direction Zb.

[0059] like Figure 1 As shown, the first brake part 50 includes a release flow path 56 and a release valve 57 disposed on the release flow path 56. The release flow path 56 is a flow path that connects the fluid reservoir 24 and the wheel cylinder 11 in a manner that bypasses the electric cylinder 51. A first end of the release flow path 56 is connected to the fourth flow path 54, while a second end of the release flow path 56 is connected to the sixth flow path 58. Specifically, the release flow path 56 connects between the fluid reservoir 24 and the input port 515 on the fourth flow path 54 and between the output port 516 and the second brake part 23 on the sixth flow path 58. The release valve 57 is a normally closed solenoid valve. Therefore, when the release valve 57 is not controlled to open, the release flow path 56 is closed.

[0060] <Second brake unit>

[0061] like Figure 1 As shown, the second brake unit 23 includes a second electric motor 64 as a power source. The second brake unit 23 can generate braking force on the vehicle wheels FL, FR, RL, and RR according to the driving force of the second electric motor 64. The second brake unit 23 is sandwiched between the first brake unit 50 and the wheel cylinder 11.

[0062] An example of the second braking portion 23 will be described.

[0063] The second brake portion 23 is a brake actuator that can independently adjust the WC pressure Pwc of each wheel FL, FR, RL, and RR. The second brake portion 23 includes pumps 631 and 632 that discharge brake fluid. The pumps 631 and 632 are driven by a second electric motor 64.

[0064] The second brake portion 23 can increase the WC pressure Pwc without increasing the hydraulic pressure of the brake fluid that has been pressure-adjusted by the first brake portion 50. The brake device 20 has a redundant configuration in which the first brake portion 50 is on the upstream side and the second brake portion 23 is on the downstream side.

[0065] The second brake portion 23 has a dual hydraulic circuit 611 and 612. The first hydraulic circuit 611 has two wheel cylinders 11 for the front wheels FL and FR connected thereto. The second hydraulic circuit 612 has two wheel cylinders 11 for the rear wheels RL and RR connected thereto.

[0066] The first hydraulic circuit 611 is connected to the reservoir 24 via a first flow path 331 and a main chamber Rm. In the first hydraulic circuit 611, a first differential pressure adjusting valve 621, which is a normally open type linear solenoid valve, is provided on a fluid path of the wheel cylinder 11 at a connection point with the first flow path 331. A check valve is provided in parallel with the first differential pressure adjusting valve 621 on the fluid path. The check valve allows the flow of brake fluid from the first flow path 331 to the wheel cylinder 11. On the other hand, the check valve restricts the flow of brake fluid from the wheel cylinder 11 to the first flow path 331.

[0067] The second hydraulic circuit 612 is connected to the reservoir 24 via a fourth flow path 54, an electric cylinder 51, and a sixth flow path 58. In the second hydraulic circuit 612, a second differential pressure adjusting valve 622, which is a normally open type linear solenoid valve, is provided on a fluid path of the wheel cylinder 11 at a connection point with the sixth flow path 58. A check valve is provided in parallel with the second differential pressure adjusting valve 622 on the fluid path. The check valve allows the flow of brake fluid from the sixth flow path 58 to the wheel cylinder 11. On the other hand, the check valve restricts the flow of brake fluid from the wheel cylinder 11 to the sixth flow path 58.

[0068] The pump 631 is provided in the first hydraulic circuit 611. The pump 631 supplies brake fluid to the fluid path connecting the first differential pressure adjusting valve 621 and the wheel cylinder 11. A check valve is provided in series between the pump 631 and the fluid path. The check valve allows the flow of brake fluid in the direction of discharge from the pump 631. On the other hand, the check valve restricts the flow of brake fluid in the direction of return of brake fluid discharged from the pump 631 to the pump 631.

[0069] A pump 632 is provided in the second hydraulic circuit 612. The pump 632 supplies brake fluid to a fluid path connecting the second differential pressure adjusting valve 622 and the wheel cylinder 11. A check valve is provided in series between the pump 632 and the fluid path. The check valve allows the flow of brake fluid in a direction from the pump 632. On the other hand, the check valve restricts the flow of brake fluid in a direction from the brake fluid discharged from the pump 632 back to the pump 632.

[0070] The same number of paths 65a, 65b as the number of wheel cylinders 11 to which the hydraulic circuit 611 is connected is provided in the hydraulic circuit 611 on the wheel cylinder 11 side compared with the first differential pressure adjusting valve 621. Similarly, the same number of paths 65c, 65d as the number of wheel cylinders 11 to which the hydraulic circuit 612 is connected is provided in the hydraulic circuit 612 on the wheel cylinder 11 side compared with the second differential pressure adjusting valve 622. Further, a hold valve 66 that closes when the increase in the hydraulic pressure of the wheel cylinder 11 is restricted and a pressure reducing valve 67 that opens when the hydraulic pressure is reduced are provided in the plurality of paths 65a to 65d. That is, the hold valve 66 is provided in the fluid path on the wheel cylinder 11 side compared with the differential pressure adjusting valves 621, 622. In addition, the plurality of hold valves 66 are solenoid valves of a normally open type, and the plurality of pressure reducing valves 67 are solenoid valves of a normally closed type.

[0071] A check valve is provided in parallel with the hold valve 66 in each of the plurality of paths 65a to 65d. The check valve allows the flow of brake fluid from the wheel cylinder 11 through the check valve in a direction to the differential pressure adjusting valves 621, 622. On the other hand, the check valve restricts the flow of brake fluid through the check valve in a direction from the differential pressure adjusting valves 621, 622 to the wheel cylinder 11.

[0072] A reservoir 681, 682 that temporarily stores brake fluid that flows from the wheel cylinder 11 through the pressure reducing valve 67 when the pressure reducing valve 67 opens is connected to the plurality of hydraulic circuits 611, 612. The plurality of reservoirs 681, 682 are connected to the pumps 631, 632 via fluid paths 691, 692 for suction.

[0073] The reservoir 681 is connected to a fluid path connecting the first differential pressure adjusting valve 621 and the main chamber Rm via a tank side fluid path 701. The reservoir 682 is connected to a fluid path connecting a connection point on the second hydraulic circuit 612 to the sixth fluid path 58 and the second differential pressure adjusting valve 622 via a tank side fluid path 702.

[0074] The plurality of pumps 631, 632 can draw brake fluid in the reservoir tank 24 via the reservoirs 681, 682. The plurality of pumps 631, 632 discharge the drawn brake fluid to a fluid path between the differential pressure adjusting valves 621, 622 and the hold valve 66. The fluid path between the pump 631, 632 and the fluid path is referred to as an "intermediate fluid path 711, 712".

[0075] ​

[0076] As Figure 1 shown, the detection system of the brake device 20 is provided with a plurality of sensors. The detection signals of the sensors are input to the control device 100 of the brake device 20. In Figure 1 , a master hydraulic pressure sensor 351, an input hydraulic pressure sensor 352, a control pressure sensor 353, a stroke sensor SE1, a rotation angle sensor SE2, and a current sensor SE3 are shown as the plurality of sensors.

[0077] The master hydraulic pressure sensor 351 detects the hydraulic pressure in the master chamber Rm. For example, the master hydraulic pressure sensor 351 is provided to the first flow path 331. The hydraulic pressure in the master chamber Rm based on the detection value of the master hydraulic pressure sensor 351 is referred to as "master pressure".

[0078] The input hydraulic pressure sensor 352 detects the hydraulic pressure in the second liquid chamber R2. For example, the input hydraulic pressure sensor 352 is connected at a position between the first control valve 341 and the second liquid chamber R2 on the second flow path 332. The hydraulic pressure of the second liquid chamber R2 based on the detection value of the input hydraulic pressure sensor 352 is referred to as "input hydraulic pressure".

[0079] 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 provided in the vicinity of the output port 516 in the electric cylinder 51. As one example, the configuration in which the control pressure sensor 353 is connected between the release valve 57 on the release flow path 56 and the output port 516 is shown in Figure 1 . The discharge hydraulic pressure of the electric cylinder 51 based on the detection value of the control pressure sensor 353 is referred to as "pressure P".

[0080] The stroke sensor SE1 detects the operation amount of the brake operation member 21.

[0081] The rotation angle sensor SE2 detects the rotation angle of the power source of the electric cylinder 51, that is, the first electric motor 513. The rotation angle of the first electric motor 513 based on the detection value of the rotation angle sensor SE2 is referred to as "rotation angle Θ". Based on the rotation angle Θ, the position of the piston 512 can be estimated. Based on the rotation angle Θ, the rotation speed S of the first electric motor 513 can be calculated.

[0082] The current sensor SE3 can detect the current value flowing through the first electric motor 513. The current value of the first electric motor 513 based on the detection value of the current sensor SE3 is referred to as "current value T".

[0083] <Control device of brake device>

[0084] The control device 100 can control various solenoid valves 341, 342, 551, 57 provided in the hydraulic pressure generating device 22 and the first electric motor 513, and various solenoid valves 621, 622, 66, 67 provided in the second brake portion 23 and the second electric motor 64.

[0085] The control device 100 can execute a piston position setting process. The piston position setting process is a process of setting a relative position of the piston 512 with respect to the input port 515 with respect to the control of the electric cylinder 51.

[0086] The piston position setting process includes a terminal movement process of moving the piston 512 to the terminal position EP and an origin movement process of moving the piston 512 from the terminal position EP to the forward direction Za by a movement amount Xm. The origin movement process can be executed after the piston 512 is moved to the terminal position EP by the terminal movement process.

[0087] Using Figure 4 The piston position setting process will be described. Figure 4 A flow of the process executed by the control device 100 is shown. For example, the control device 100 can execute the present process routine at the time of starting the brake device 20. The brake device 20 is started, for example, in a case where the start switch of the vehicle is changed from off to on.

[0088] If the present process routine is started, first, in step S101, the control device 100 starts the drive of the first electric motor 513 in order to move the piston 512 to the backward direction Zb. At this time, the control device 100 performs feedback control to make the rotation speed S of the first electric motor 513 follow the target rotation speed ST. The target rotation speed ST is, for example, a constant value set in advance. If the drive of the first electric motor 513 is started, the control device 100 moves the process to step S102.

[0089] In step S102, the control device 100 determines whether or not the piston 512 reaches the terminal position EP. Here, the control device 100 detects that the piston 512 reaches the terminal position EP, for example, in a case where the current value T is larger than the second determination value Tth2 and the rotation speed S is smaller than the first threshold value Sth1.

[0090] The first threshold value Sth1 is set as a threshold value for determining whether or not the rotation of the first electric motor 513 is stopped. For example, if the rotation speed S of the first electric motor 513 is changed to be smaller than the first threshold value Sth1 at the first threshold value Sth1 or more, it can be determined that the rotation of the first electric motor 513 is stopped.

[0091] The second determination value Tth2 can be set to a value larger than the inrush current at the time of starting the drive of the first electric motor 513, for example.

[0092] The control device 100 determines that the piston 512 reaches the end position EP in a case where the rotation of the first electric motor 513 is stopped and a current value T larger than the impact current is detected.

[0093] In the processing of step S102, in a case where the piston 512 is detected to reach the end position EP (S102: YES), the control device 100 causes the processing to move to step S111.

[0094] In step S111, the control device 100 temporarily stops the drive of the first electric motor 513. At this time, the control device 100 can also acquire the rotation angle Θ at the time when the drive of the first electric motor 513 is stopped, as an end rotation angle Θep. The end rotation angle Θep corresponds to the rotation angle Θ at the time when the piston 512 moves to the end position EP. If the drive of the first electric motor 513 is stopped, the control device 100 causes the processing to move to step S121.

[0095] On the other hand, in a case where the piston 512 is not detected to reach the end position EP (S102: NO), the control device 100 causes the processing to move to step S103. In step S103, the control device 100 determines whether the rotation speed S is larger than a second threshold value Sth2.

[0096] The second threshold value Sth2 is set as a threshold value for determining whether the first electric motor 513 starts to operate. The second threshold value Sth2 is a value larger than the first threshold value Sth1. For example, if the rotation speed S below the second threshold value Sth2 becomes larger than the second threshold value Sth2, it can be determined that the first electric motor 513 starts to operate. Here, the start of the operation of the first electric motor 513 means that the piston 512 starts to move in the backward direction Zb.

[0097] In a case where the rotation speed S is below the second threshold value Sth2 (S103: NO), the control device 100 causes the processing to move to step S102 again. On the other hand, in a case where the rotation speed S is larger than the second threshold value Sth2 (S103: YES), the control device 100 causes the processing to move to step S104.

[0098] In step S102 and step S103, the processing of step S102 is repeatedly executed until the rotation speed S is larger than the second threshold value Sth2, that is, until the first electric motor 513 starts to operate, by the processing of step S103.

[0099] Further, in a case where at least one of the rotation speed S is equal to or higher than the first threshold value Sthl and the current value T is lower than the second determination value Tth2 is satisfied before the first electric motor 513 starts to operate, the processing is performed as follows. The processing of step S102 is repeated since the negative determination is made in step S102 and the negative determination is made in step S103. On the other hand, in a case where the current value T is greater than the second determination value Tth2 and the rotation speed S is lower than the first threshold value Sthl before the first electric motor 513 starts to operate, it is determined that the piston 512 has reached the end position EP, and the processing is moved to step Slll. As a result, the driving of the first electric motor 513 is temporarily ended.

[0100] Further, the "case where at least one is satisfied" means the following cases. The rotation speed S is equal to or higher than the first threshold value Sthl and the current value T is greater than the second determination value Tth2. Or, the rotation speed S is lower than the first threshold value Sthl and the current value T is lower than the second determination value Tth2. Or, the rotation speed S is equal to or higher than the first threshold value Sthl and the current value T is lower than the second determination value Tth2.

[0101] In step S104, the control device 100 determines whether the rotation speed S reaches the target rotation speed ST.

[0102] In a case where the rotation speed S does not reach the target rotation speed ST (S104: No), the control device 100 moves the processing to step S104. That is, the control device 100 repeatedly performs the determination whether the rotation speed S reaches the target rotation speed ST until the rotation speed S reaches the target rotation speed ST. During this period, the difference between the rotation speed S and the target rotation speed ST becomes small as time elapses by continuing the feedback control of the first electric motor 513. The control device 100 can determine whether the rotation speed S reaches the target rotation speed ST based on the rotation speed S and the target rotation speed ST, for example. The determination whether the rotation speed S reaches the target rotation speed ST can also be made based on the duration for which the rotation speed S is greater than the second threshold value Sth2 continues. For example, it can be determined that the rotation speed S reaches the target rotation speed ST in a case where the duration for which the rotation speed S is greater than the second threshold value Sth2 is longer than the rotation speed determination time calculated in advance by experiment or the like.

[0103] In a case where the rotation speed S reaches the target rotation speed ST, that is, in a case where the first electric motor 513 rotates in such a manner that the rotation speed S follows the target rotation speed ST (S104: Yes), the control device 100 moves the processing to step S105. In step S105, the control device 100 sets the first determination value Tthl. The control device 100 sets the first determination value Tthl based on the current value T flowing through the first electric motor 513 when the rotation speed S follows the target rotation speed ST after the first electric motor 513 starts to operate.

[0104] The first determination value Tth1 will be described in more detail.

[0105] The first determination value Tth1 is a value set for determining that the piston 512 has moved to the end position EP. The control device 100 sets the first determination value Tth1 as a reference value of the current value T when the rotation speed S of the first electric motor 513 is following the target rotation speed ST. In addition, the first determination value Tth1 is set to a value smaller than the second determination value Tth2.

[0106] For example, the first determination value Tth1 can be calculated as a value increased by an increase amount d from the current value T when the rotation speed S is following the target rotation speed ST. The increase amount d is a prescribed amount set based on the elasticity that the elastic body 518 has. In the electric cylinder 51 provided with the elastic body 518, the piston 512 that has moved to a position in contact with the elastic body 518 moves in the retreat direction Zb while elastically deforming the elastic body 518, and thus the current value T gradually increases. The first determination value Tth1 is a value corresponding to the current value T when the piston 512 is moved to the end position EP while elastically deforming the elastic body 518. For example, the more difficult it is for the elastic body 518 to be elastically deformed, the larger the increase amount d can be.

[0107] If the first determination value Tth1 is set, the control device 100 causes the process to proceed to step S106.

[0108] In step S106, the control device 100 determines whether the current value T is larger than the first determination value Tth1. In the case where the current value T is larger than the first determination value Tth1 (S106: YES), the control device 100 causes the process to proceed to step S110. On the other hand, in the case where the current value T is equal to or smaller than the first determination value Tth1 (S106: NO), the control device 100 causes the process to proceed to step S107.

[0109] In step S107, the control device 100 determines whether the rotation speed S is smaller than the first threshold value Sth1. In the case where the rotation speed S is smaller than the first threshold value Sth1, that is, in the case where the rotation of the first electric motor 513 has stopped (S107: YES), the control device 100 causes the process to proceed to step S110. For example, in the case where the rotation of the first electric motor 513 has stopped before the current value T is detected to be larger than the first determination value Tth1, affirmative determination is made in the process of step S107 and the process is caused to proceed to step S110. On the other hand, in the case where the rotation speed S is equal to or larger than the first threshold value Sth1, that is, in the case where the rotation of the first electric motor 513 has not stopped (S107: NO), the control device 100 causes the process to proceed to step S108.

[0110] In step S108, the control device 100 determines whether the time for which the first electric motor 513 is driven to move the piston 512 in the backward direction Zb, i.e., the backward time, is longer than a determination time. The determination time is a value calculated in advance through experiments or the like. The determination time can be set to, for example, the time required to move the piston 512 from the end portion in the forward direction Za to the end portion BE in the backward direction Zb when the first electric motor 513 is driven at the target rotational speed ST. That is, the time for which the first electric motor 513 is driven is longer than the determination time means that an abnormality occurs. The state in which the piston moves to the end portion BE in the backward direction Zb is a state in which the piston 512 cannot further move backward even if the largest driving force is generated in moving the piston 512 in the backward direction Zb. Alternatively, the state in which the piston moves to the end portion BE in the backward direction Zb is a state in which the piston 512 cannot further move backward in terms of mechanical structure in moving the piston 512 in the backward direction Zb. The use of the determination time makes it possible to determine whether the piston 512 has moved to the end portion BE in the backward direction Zb. The determination time can be set to, for example, the time required to move the piston 512 from the end portion in the forward direction Za to the end portion BE in the backward direction Zb when the first electric motor 513 is driven at the target rotational speed ST. That is, the time for which the first electric motor 513 is driven is longer than the determination time means that an abnormality occurs. The state in which the piston moves to the end portion BE in the backward direction Zb is a state in which the piston 512 cannot further move backward even if the largest driving force is generated in moving the piston 512 in the backward direction Zb. Alternatively, the state in which the piston moves to the end portion BE in the backward direction Zb is a state in which the piston 512 cannot further move backward in terms of mechanical structure in moving the piston 512 in the backward direction Zb. The use of the determination time makes it possible to determine whether the piston 512 has moved to the end portion BE in the backward direction Zb. Figure 6 The description will be continued.

[0111] In Figure 6 the present embodiment, the piston 512 moves in the backward direction Zb with respect to the end point position EP, and the piston 512 abuts against the rear inner wall 511a of the cylinder 511 via the elastic body 518. At this time, the disc-shaped spring as the elastic body 518 is deformed to the limit, and thus becomes a flat plate. For example, as shown in FIG. 6, in the state in which the piston 512 abuts against the rear inner wall 511a via the elastic body 518, the end surface of the piston 512 in the backward direction Zb moves to the end portion BE in the backward direction Zb. Further, in a configuration in which the elastic body is not provided, the state in which the end surface of the piston in the backward direction is in contact with the rear inner wall corresponds to the state in which the piston moves to the end portion in the backward direction. Figure 6

[0112] Returning to Figure 4 , in the case where the backward time is longer than the determination time in step S108 (S108: YES), the control device 100 causes the process to proceed to step S109. In step S109, the control device 100 determines that an abnormality occurs in the detection of the end point position EP. For example, the control device 100 can store the case where an abnormality occurs as history in a storage medium such as a memory. Thereafter, the control device 100 ends the present processing routine. On the other hand, in the case where the backward time is equal to or shorter than the determination time (S108: NO), the control device 100 causes the process to proceed to step S106 again.

[0113] ​If the processes of steps S106, S107, and S108 are summarized, the following can be stated. That is, in a case where either of the current value T is greater than the first determination value Tthl and the rotation speed S is less than the first threshold value Sthl is established during the retreat time is below the determination time, the process of step S110 is executed. In a case where neither of the current value T is greater than the first determination value Tthl and the rotation speed S is less than the first threshold value Sthl is established during the retreat time is below the determination time, the drive of the first electric motor 513 is continued.

[0114] In step S110, the control device 100 temporarily stops the drive of the first electric motor 513. That is, the control device 100 determines that the piston 512 reaches the end position EP and ends the drive of the first electric motor 513 in a case where the current value T increases compared with the first determination value Tthl. Alternatively, the control device 100 determines that the piston 512 reaches the end position EP and ends the drive of the first electric motor 513 in a case where the rotation speed S is less than the first threshold value Sthl.

[0115] Also, in step S110, the control device 100 acquires the rotation angle Θ of the time when the piston 512 reaches the end position EP as the end rotation angle Θep. For example, the control device 100 acquires the rotation angle Θ of the time when the current value T increases compared with the first determination value Tthl as the end rotation angle Θep. For example, the control device 100 acquires the rotation angle Θ of the time when the rotation speed S becomes less than the first threshold value Sthl as the end rotation angle Θep. After the process of step S110 is performed, the control device 100 shifts the process to step S121.

[0116] In step S121, the control device 100 starts the drive of the first electric motor 513 in order to move the piston 512 in the advancing direction Za. The control device 100 ends the drive of the first electric motor 513 if the piston 512 is moved in the advancing direction Za by a prescribed movement amount Xm. The movement amount Xm is a value calculated in advance by experiment or the like as the movement amount of the piston 512 from the end position EP to the origin position OP.

[0117] The control device 100 drives the first electric motor 513 based on the end rotation angle Θep and a rotation angle for moving the piston 512 in the advancing direction Za by the movement amount Xm to move the piston 512 in the advancing direction Za.

[0118] In other words, the control device 100 moves the piston 512 to a position that is a distance Xm in the advancing direction Za from a position of the piston 512 corresponding to the end point rotation angle θep as a base point. Therefore, the amount by which the piston 512 actually moves in the advancing direction Za from the time when the driving of the first electric motor 513 is started in order to move the piston 512 in the advancing direction Za is not necessarily equal to the distance Xm.

[0119] Further, the control device 100 also has a case where the process of step S111 is followed by the process of step S121. In this case, the control device 100 can also drive the first electric motor 513 to move the piston 512 in the advancing direction Za by the distance Xm from the time when the driving of the first electric motor 513 is started in order to move the piston 512 in the advancing direction Za.

[0120] If the piston 512 is moved in the advancing direction Za in the process of step S121, the control device 100 moves the process to step S122.

[0121] In step S122, the control device 100 determines whether the pressure P is less than the closing determination value Pth.

[0122] The closing determination value Pth is a value that indicates that the input port 515 is closed by the piston 512 in a case where the pressure P is equal to or higher than the closing determination value Pth, and is set to a value that is calculated in advance through experiments or the like. Therefore, the pressure P being less than the closing determination value Pth indicates that the input port 515 is not closed by the piston 512. That is, it indicates that the piston 512 is positioned at a position that is further in the retreating direction Zb than a position at which the input port 515 is closed by the piston 512.

[0123] In a case where the pressure P is less than the closing determination value Pth (S122: YES), the control device 100 ends the present processing routine. The control device 100 acquires the position of the piston 512 at this time as the origin position OP. For example, the control device 100 updates the origin position OP stored in a storage medium such as a memory to the newly acquired origin position OP. The origin position OP can be acquired as the rotation angle θ of the first electric motor 513, for example.

[0124] On the other hand, in a case where the pressure P is equal to or higher than the closing determination value Pth (S122: NO), the control device 100 moves the process to step S123. The pressure P being equal to or higher than the closing determination value Pth can be estimated as the piston 512 being excessively moved in the advancing direction Za.

[0125] In step S123, the control device 100 determines that an abnormality has occurred in the detection of the origin position OP. For example, the control device 100 can also store a case where an abnormality has occurred as history in a storage medium such as a memory. Thereafter, the control device 100 ends the present processing routine.

[0126] In the flow of the processing shown in the above description Figure 4 The processing of steps S101 to S111 corresponds to the end point moving processing. The processing of steps S121 to S123 corresponds to the origin point moving processing.

[0127] The end point rotation angle θep acquired in the processing of step S110 can be eliminated at the end of the piston position setting processing, or can be maintained after the end of the piston position setting processing by storing as a rotation angle θ corresponding to the end point position EP.

[0128] <Effects>

[0129] The effects of the present embodiment will be described.

[0130] Using Figure 5 One example of the control device 100 performing the piston position setting processing in the electric cylinder device will be described.

[0131] In the example shown in Figure 5 The piston position setting processing is started at time t1. In other words, the end point moving processing is started at time t1.

[0132] As shown in (a) of Figure 5 The current value T starts to increase at time t1. A rush current is temporarily generated after time t1. Further, in (a) of Figure 5 The second determination value Tth2 is exemplified in (a) of

[0133] As shown in (b) of Figure 5 During the period from time t1 to time t2, the rotation speed S starts to increase. At time t2, the rotation speed S increases to the second threshold value Sth2. Further, in (b) of Figure 5 The first threshold value Sth1 which is a value smaller than the second threshold value Sth2 is exemplified in (b) of

[0134] Thereafter, at time t3, as shown in (b) of Figure 5 The rotation speed S reaches the target rotation speed ST. Thereby, the processing of setting the first determination value Tth1 is performed (S105). If time t3 elapses, as shown in (a) of Figure 5 The current value T is shifted at a constant value through the period during which the rush current is generated. In Figure 5 The current value T at this time is shown as a reference current value Tx. The control device 100 sets a value which is increased by an increase amount d compared to the reference current value Tx as the first determination value Tth1.

[0135] After time t3, the rotation speed S follows the target rotation speed ST. Therefore, the estimated position of the piston 512 is as shown in Figure 5As shown in (c), the movement approaches the end position EP at a constant speed.

[0136] At time t4, if Figure 5 As shown in (a), the current value T begins to increase compared to the reference current value Tx. Figure 5 As shown in (b), the rotation speed S begins to decrease. This is because at time t4, the piston 512 comes into contact with the elastic body 518. As the elastic body 518 elastically deforms, the current value T increases and the rotation speed S decreases.

[0137] At time t5, if Figure 5 As shown in (a), the current value T is larger than the first determination value Tth1. Therefore, the driving of the first electric motor 513 is stopped (S110). Then, the control device 100 obtains the rotation angle θ at this time as the end point rotation angle θep.

[0138] Here, if the piston is moved to abut against the end in the backward direction, there is a concern that the load applied to the electric motor will increase, causing the current value to increase excessively. In this case, not only will the load on the electric motor increase, but as the piston abuts, there is a possibility that excessive load will be applied to components of the electric cylinder other than the electric motor.

[0139] In this regard, the electric cylinder device of this embodiment uses a value increased by an amount d from the reference current value Tx as the first determination value Tth1. This allows the determination that the end position EP has been reached before the current value T increases excessively. In other words, the current value T is less likely to increase excessively before the piston 512 completes its movement in the backward direction Zb. Therefore, the driving of the first electric motor 513 can be stopped before the current value T increases excessively. This prevents excessive load from being applied to the electric cylinder 51.

[0140] In the electric cylinder device of this embodiment, the inclusion of the elastic body 518 reduces the rate of change in the current value T while the elastic body 518 is elastically deformed by the movement of the piston 512 in the backward direction Zb. For example, this rate of change is gentler than in an electric cylinder device without an elastic body, where the piston is brought into contact with the end portion in the backward direction. Therefore, a sharp increase in the current value T can be suppressed when detecting the end position EP. This prevents the current value T from increasing excessively. Furthermore, according to the electric cylinder device of this embodiment, the end position EP can be detected while the elastic body 518 is elastically deformed. Thus, in the electric cylinder device of this embodiment, the end position EP can be detected without bringing the piston 512 into contact with the end portion BE in the backward direction Zb.

[0141] exist Figure 4The origin movement processing can be executed after the time t5, that is, after the end of the end point movement processing. As a result of executing the origin movement processing, the piston 512 moves to a position that is distanced from the position corresponding to the end point rotation angle θep by the movement amount Xm in the advancing direction Za. Thus, the control device 100 can set the origin position OP based on the end point rotation angle θep and the movement amount Xm.

[0142] Since the driving of the first electric motor 513 is ended at the time t5, the piston 512 also stops the movement in the retreating direction Zb. In the example shown in (c) of FIG. 9, the position of the piston 512 after the time t5 is moved from the position of the piston 512 at the time point of the time t5. Figure 6

[0143] Thus, even after the driving of the first electric motor 513 is temporarily ended in the judgment of reaching the end point position EP, there are cases where the piston 512 moves without depending on the driving of the first electric motor 513. For example, there are cases where the piston 512 moves in the retreating direction Zb due to a response delay after the first electric motor 513 is stopped. For example, there are cases where the piston 512 moves due to the piston 512 being pressed in the advancing direction Za by the elastic body 518. If the piston 512 further moves after the movement of the piston 512 by the end point movement processing is ended, an error in setting the origin position OP can occur.

[0144] In view of this, the electric cylinder device of the present embodiment is configured to acquire the rotation angle θ at the time of reaching the end point position EP as the end point rotation angle θep, and thereby drive the first electric motor 513 based on the end point rotation angle θep when the piston 512 is moved in the advancing direction Za. Thus, the piston 512 can be correctly moved by the movement amount Xm from the position detected as the end point position EP. Thereby, the origin position OP can be set with good precision.

[0145] However, in the electric cylinder 51, there are cases where the dynamic frictional resistance when the piston 512 is moved varies. For example, there are cases where the dynamic frictional resistance varies due to expansion, contraction, aging change, or the like of the components that constitute the electric cylinder 51. In the case where the dynamic frictional resistance when the piston 512 is moved varies, the torque generated by the first electric motor 513 varies depending on the dynamic frictional resistance. Thus, for example, the current value T that flows through the first electric motor 513 when the rotational speed S is caused to follow the target rotational speed ST varies. In a configuration where it is intended to detect that the piston 512 reaches the end point position EP based on the change in the current value T, assuming that the variation in the dynamic frictional resistance is not taken into account, the variation in the dynamic frictional resistance can become an important factor in lowering the precision in the judgment of reaching the end point position EP.

[0146] ​For this, the electric cylinder device of the present embodiment sets the current value T at the time when the rotation speed S follows the target rotation speed ST as the reference current value Tx to the first determination value Tthl. For example, if the current value T at the time when the rotation speed S follows the target rotation speed ST is large, the first determination value Tthl is also increased. For example, if the current value T at the time when the rotation speed S follows the target rotation speed ST is small, the first determination value Tthl is also decreased. Therefore, even in the case where the dynamic frictional resistance varies as described above, it is possible to ensure the accuracy of determination of the end position EP. Thus, it is possible to reduce the deviation of the estimated end position EP. By detecting the end position EP with good accuracy, it is possible to set the origin position OP with good accuracy.

[0147] According to the electric cylinder device of the present embodiment, it is possible to set the origin position OP with good accuracy, so it is possible to improve the responsiveness at the time of hydraulic pressure generation by controlling the electric cylinder 51.

[0148] In the electric cylinder device of the present embodiment, in the case where it has been determined that the end position EP is reached before the piston 512 starts to move, it is possible to set the position of the piston 512 at that time as the end position EP (S111). Thus, it is possible to suppress the case where the first electric motor 513 is continued to be driven even though the piston 512 moves to the end portion BE in the retreat direction Zb.

[0149] (Variations)

[0150] The present embodiment can be implemented as follows. The present embodiment and the following variations can be implemented in combination with each other within a range where there is no technical contradiction.

[0151] • In the above-described embodiment, the processing routine is ended after the processing of step S109 of ​ is performed. Instead of this, it is also possible to perform the processing of moving the piston 512 in the advance direction Za after the processing of step S109 is performed. For example, it is also possible to move the processing to step S121 after the processing of step S109 is performed. In this case, for example, the piston 512 is moved in the advance direction Za by the movement amount Xm from the position of the piston 512 at the time when the affirmative determination is made in the processing of step S108.

[0152] • In the above embodiment, as the step S102, an example is shown in which the piston 512 is detected to reach the end position EP in a case where the current value T is larger than the second determination value Tth2 and the rotation speed S is smaller than the first threshold value Sthl. Instead of this case, as the process of the step S102, it is also possible to determine whether or not the piston 512 reaches the end position EP regardless of the rotation speed S. For example, it is also possible to make the process proceed to the step S103 in a case where the current value T is below the second determination value Tth2 and proceed to the step Sll l in a case where the current value T is larger than the second determination value Tth2 in the step S102.

[0153] • The above embodiment is configured to make the process proceed to the step S121 after the step Sll l, and thereby the origin moving process of the steps S121 to S123 is executed. Instead of this case, it is also possible to execute the following retry process after the step Sll l. For example, in the retry process, the piston 512 is moved by a predetermined retry distance in the advancing direction Za after the process of the step Sll l stops the driving of the first electric motor 513. Thereafter, the process returns to the step S101, and the piston position setting process is started again. In a case where the process of the step Sll l and the retry process are repeatedly executed in this way, for example, it is also possible to determine that an abnormality occurs and not perform the retry process when the retry process is executed a predetermined maximum number of times from the start of the piston position setting process. In a case where the retry process is not performed, for example, it is also possible to execute the origin moving process by making the process proceed from the step Sll l to the step S121.

[0154] • The brake fluid exemplified in the above embodiment is one example of the working fluid. The wheel cylinder 11 for the rear wheels RL, RR in the above embodiment is one example of the supply target of the working fluid supplied by the electric cylinder 51. The master cylinder 31 is one example of the supply target of the working fluid supplied by the electric cylinder 51. The wheel cylinder 11 for the front wheels FL, FR is supplied with the brake fluid discharged from the electric cylinder 51 via the master cylinder 31. Therefore, the wheel cylinder 11 for the front wheels FL, FR can also be said to be one example of the supply target of the working fluid supplied by the electric cylinder 51.

[0155] • With respect to the elastic body, for example, if the elastic body is plastically deformed due to the application of an excessively large load or the repeated application of a load, there is a possibility that a phenomenon of elastic change, so-called creep, occurs.

[0156] If it is assumed that the creep occurs in the elastic body 518, the force by which the elastic body 518 presses the piston 512, which has moved to the end portion on the retreating direction Zb of the cylinder 511, in the advancing direction Za becomes small. In this case, when the piston 512 is moved to the end position EP, the piston 512 is not pressed by the elastic body 518 in the advancing direction Za, and the piston 512 is not moved to the end position EP. In this case, the piston 512 is not moved to the end position EP, and the piston position setting process is not completed. ​The piston 512 is shown as abutting against the rear inner wall 511a of the cylinder 511 via the elastic body 518. Therefore, it is preferable to set the increase amount d so that the piston 512 is determined to have moved to the end position EP before the piston 512 abuts against the rear inner wall 511a of the cylinder 511 via the elastic body 518 even in a case where the elastic body 518 is assumed to have undergone creep. That is, the increase amount d can also be a value set in consideration of the creep that the elastic body 518 can undergo. Also, the increase amount d can be set so that the pressing force of the piston 512 in a case where the first electric motor 513 is driven in such a manner that a current value increased by the increase amount d from the reference current value Tx flows can be as follows. The increase amount d can also be set so that even if the deformation of the elastic body 518 caused by the pressing of the piston 512 is repeated a prescribed number of times, the pressing force of the elastic body 518 can be limited within an allowable range.

[0157] The processing circuit of the control device 100 or the like can be configured as follows. The processing circuit can be configured as a circuit including one or more processors that execute various processes according to computer programs. The processing circuit can be configured as a circuit including one or more hardware circuits that execute various processes. The processing circuit can be configured as a circuit in which one or more processors that execute part of the various processes and one or more hardware circuits that execute the remaining processes of the various processes are combined.

[0158] The processor includes a processing device such as a CPU. The processor includes a memory such as a RAM and a ROM. The memory stores program codes or instructions that cause the processing device to execute processes. The memory, that is, the storage medium includes all usable media that can be accessed by a general-purpose or special-purpose computer. As the hardware circuit, for example, an application-specific integrated circuit (ASIC) can be cited. As other examples of the hardware circuit, a FPGA or the like can be cited.

Claims

1. An electric cylinder device comprising: a liquid reservoir that stores working liquid; an electric cylinder configured to supply the working liquid to a supply target by moving a piston in a cylinder in accordance with driving of an electric motor; and a control device that controls the electric motor, the electric cylinder device supplies the working liquid to the supply target, the electric cylinder has a hydraulic chamber that is divided by the cylinder and the piston in the cylinder, an input port that communicates the liquid reservoir with the hydraulic chamber, and an output port that discharges the working liquid of the hydraulic chamber toward the supply target, a direction in which a volume of the hydraulic chamber is reduced in a moving direction of the piston is set as a forward direction, and a direction opposite to the forward direction in the moving direction of the piston is set as a backward direction, the control device uses a home position to drive the electric motor when moving the piston, the home position is a position at which the piston is moved to an end portion in the backward direction as a final position, and a position at which the piston is moved from the final position in the forward direction by a prescribed movement amount, the electric cylinder has an elastic body that exerts a force to press the piston in the forward direction on the piston when the piston is positioned at the final position, the electric cylinder is configured such that the input port is open when the piston is positioned at the home position, and the hydraulic pressure of the hydraulic chamber is increased by the input port being closed by the piston if the piston is moved from the home position in the forward direction, the control device performs a final movement process of moving the piston to the final position in order to set a relative position of the piston with respect to the input port, the final movement process drives the electric motor such that a rotational speed of the electric motor becomes a target rotational speed to move the piston in the backward direction, and ends the driving of the electric motor when a current value flowing through the electric motor is increased compared to a determination value, and determines that the piston reaches the final position, the determination value is a value that is increased by an increase amount compared to a current value flowing through the electric motor when the rotational speed of the electric motor follows the target rotational speed.

2. The electric cylinder device according to claim 1, wherein the control device sets the determination value after the electric motor starts operating in the final movement process.

3. The electric cylinder device according to claim 2, wherein the determination value is a first determination value, the control device determines that the piston reaches the final position and ends the driving of the electric motor when a current value flowing through the electric motor before the electric motor starts operating is increased compared to a second determination value in the final movement process, and the control device sets the first determination value to be a value smaller than the second determination value. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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