braking device

Abstract

When a deviation in an output of a pilot pressure sensor 353 is confirmed, a control unit 100 performs an output calibration for the pilot pressure sensor 353 in a state where a piston 512 of an electric cylinder 51 moves from a standby position in the retraction direction Zb.

Description

Technical field

[0001] The present invention relates to a braking device comprising an electric cylinder. State of the art

[0002] A device disclosed in PTL 1 is known as a braking device comprising an electric cylinder. The electric cylinder includes a piston movably housed within the cylinder, a hydraulic chamber defined by a circumferential wall of the cylinder and the piston, and an electric motor that drives the piston. The braking device generates a braking force by supplying brake fluid discharged from the electric cylinder to a wheel cylinder. The braking device further includes a hydraulic pressure sensor that detects the hydraulic pressure of the brake fluid discharged from the electric cylinder. Citation list of patent specifications

[0003] PTL 1: JP2009-137376A Brief description of the invention: Technical problem

[0004] The output characteristics of the hydraulic pressure sensor provided in such a device can change depending on environmental conditions or similar factors. The sensing accuracy of the hydraulic pressure sensor can decrease due to these changes in output characteristics. Solution to the problem

[0005] A braking device for solving the above problem comprises a reservoir tank configured to store brake fluid, an electric cylinder configured to discharge the brake fluid by moving a piston within the cylinder in response to drive by an electric motor, a hydraulic pressure sensor configured to detect the hydraulic pressure of the brake fluid being discharged by the electric cylinder, and a control unit configured to control the electric motor. The control device generates a braking force on a wheel by supplying brake fluid to a wheel cylinder in response to the discharge of brake fluid from the electric cylinder.The electric cylinder of the device comprises a hydraulic chamber, defined by a circumferential wall of the cylinder and the piston, an inlet port, which serves as an inlet for brake fluid from the reservoir tank into the hydraulic chamber, and an outlet port, which serves as an outlet for brake fluid from the hydraulic chamber. The electric cylinder is configured such that the inlet port is open when the piston is in a retraction limit position, and when the piston moves from the retraction limit position into a forward direction and the inlet port is closed, the hydraulic pressure in the hydraulic chamber increases and the brake fluid is discharged from the outlet port.The brake device's control unit holds the piston in a standby position, which lies between the position where the input port is switching between a closed and an open state, and the retraction limit position when braking force generation is not required. The control unit directs the electric motor to move the piston forward from the standby position when braking force generation is requested. After instructing the electric motor to move the piston in a retraction direction relative to the standby position, the control unit performs the output calibration processing for the hydraulic pressure sensor. The forward direction here specifies the direction of piston movement to reduce the volume of the hydraulic chamber. The retraction direction here specifies the direction opposite to the forward direction.The retraction limit position indicates the furthest position in the retraction direction within a movable area of ​​the piston.

[0006] At the start of the calibration process, there is a possibility that the piston has not returned to its ready position and the input port is not open. In response, during the calibration process, the brake device's control unit instructs the electric motor to move the piston in the direction of travel relative to the ready position and then performs the output calibration for the hydraulic pressure sensor. Therefore, even if the input port is not open at the start of the calibration process, there is a high probability that it will open when the output calibration is performed. Consequently, the output calibration for the hydraulic pressure sensor can be performed simply, provided that the hydraulic pressure is equivalent to atmospheric pressure.Therefore, the braking device has the effect that the detection accuracy of the hydraulic pressure sensor can be easily maintained with respect to a change in the output characteristics.

[0007] Another braking device for solving the above problem includes a reservoir tank configured to store brake fluid, an electric cylinder configured to discharge the brake fluid by moving a piston within the cylinder in response to drive by an electric motor, a hydraulic pressure sensor configured to detect the hydraulic pressure of the brake fluid being discharged by the electric cylinder, and a control unit configured to control the electric motor. The control device generates a braking force on a wheel by supplying brake fluid to a wheel cylinder in response to the discharge of brake fluid from the electric cylinder.The electric cylinder of the device comprises a hydraulic chamber, defined by a circumferential wall of the cylinder and the piston, an inlet port, which serves as an inlet for brake fluid from the reservoir tank into the hydraulic chamber, and an outlet port, which serves as an outlet for brake fluid from the hydraulic chamber. The electric cylinder is configured such that the inlet port is open when the piston is in a retraction limit position, and when the piston moves from the retraction limit position into a forward direction and the inlet port is closed, the hydraulic pressure in the hydraulic chamber increases and the brake fluid is discharged from the outlet port.The brake device further includes a release flow path configured to connect the outlet port to the reservoir tank without passing through the hydraulic pressure chamber, and a release valve configured to open and close the release flow path. The brake device's control unit holds the piston in a ready position, which lies between the position where the input port switches between a closed and an open state, and the retraction limit position when brake force generation is not requested. The control unit controls the electric motor to move the piston forward from the ready position when brake force generation is requested. Additionally, the control unit performs a calibration process to calibrate the hydraulic pressure sensor output in a state where the release valve is open.

[0008] During calibration, the brake device's control unit performs the output calibration for the hydraulic pressure sensor after the release valve opens. When the release valve opens, the electric cylinder's output port and the reservoir tank are connected via the release flow path. Therefore, the hydraulic pressure detected by the sensor is equivalent to atmospheric pressure, regardless of whether the input port is open. Consequently, the output calibration for the hydraulic pressure sensor can be performed assuming that the hydraulic pressure is equivalent to atmospheric pressure. This ensures that the brake device's detection accuracy can be easily maintained even with changes in output characteristics. (Brief description of the drawings) Fig. Figure 1 is a schematic representation of an embodiment of a brake device according to a first and a second embodiment. Fig. Figure 2 is a flowchart of a calibration performed by a control unit provided in the brake device according to the first embodiment. Fig. Figure 3 is a flowchart of a calibration routine performed by a braking section provided in the braking device according to the second embodiment. Description of exemplary embodiments (First exemplary embodiment)

[0009] A braking device according to a first embodiment is described with reference to the Fig. 1 to 3 described. Fig. Figure 1 illustrates a plurality of wheels and a plurality of braking mechanisms 10 together with a braking device 20 according to the exemplary embodiment. The plurality of wheels includes two front wheels and two rear wheels. For example, in Fig. 1 one wheel FL a left front wheel, one wheel FR a right front wheel, one wheel RL a left rear wheel and one wheel RR a right rear wheel. <Konfiguration des Bremsmechanismus 10>

[0010] First, a configuration of the brake mechanism 10 is described. A brake mechanism 10 is provided for each wheel. Each brake mechanism 10 comprises a wheel cylinder 11, to which a brake fluid is supplied, a rotating plate 12 that rotates integrally with the wheel, and a friction material 13 that is pressed against the rotating plate 12. The brake mechanism 10 generates a braking force on the wheel by pressing the friction material 13 against the rotating plate 12 through hydraulic pressure supplied to the wheel cylinder 11. <Konfiguration der Bremsvorrichtung 20>

[0011] Next, a configuration of the brake device 20 is described. The brake device 20 comprises a brake actuation element 21, a hydraulic pressure generating device 22, a brake actuator 23, a reservoir tank 24, and a control unit 100. The brake actuation element 21 is an element that is actuated when a driver requests braking of a vehicle. An example of the brake actuation element 21 is a brake pedal. The reservoir tank 24 is a reservoir in which the brake fluid is stored. The reservoir tank 24 is open to the atmosphere. Therefore, the hydraulic pressure of the brake fluid in the reservoir tank 24 is essentially equal to atmospheric pressure. The hydraulic pressure generating device 22 is a device that generates hydraulic pressure according to an actuation of the brake actuation element 21. The hydraulic pressure generating device 22 comprises a master device 30 and a brake section 50.The master device 30 can supply the brake fluid to the brake actuator 23. The brake section 50 can supply the brake fluid to both the master device 30 and the brake actuator 23. The control unit 100 controls the operation of the brake device 20. <Konfiguration der Master-Vorrichtung 30>

[0012] Next, a configuration of the master device 30 is described. The master device 30 comprises a master cylinder 31 and a lifting simulator 32.

[0013] The master cylinder 31 comprises a main cylinder 41 and a cover cylinder 42. The master cylinder 31 further comprises a main piston 43 and an input piston 44. The master cylinder 31 also includes a main spring 45, which biases the main piston 43, and an input spring 46, which biases the input piston 44. The master cylinder 43 and the input piston 44 can move relative to the main cylinder 41 and the cover cylinder 42.

[0014] The main cylinder 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 an axis of the bottom wall 411. The main cylinder 41 further comprises a second circumferential wall 413 extending from a rear end of the first circumferential wall 412 along an axis of the first circumferential wall 412, and a first annular wall 414 extending from a rear end of the second circumferential wall 413 toward an axis of the second circumferential wall 413. Both the first circumferential wall 412 and the second circumferential wall 413 are tubular in shape. A hole is formed in the first annular wall 414 into which a rear section of the master piston 43, described later, is inserted. The inner diameter of the first circumferential wall 412 is smaller than the inner diameter of the second circumferential wall 413.

[0015] A master chamber Rm is formed in the main cylinder 41 by the bottom wall 411, the first circumferential wall 412, and the main piston 43. In the following, a left side in the master cylinder 31 is described. Fig. 1. A direction of movement of the main piston 43 for reducing the volume of the master chamber Rm is referred to as the "front," and a direction opposite to the front is referred to as the "rear." The rear is also a direction for increasing the volume of the master chamber Rm.

[0016] In the master cylinder 41, a first fluid chamber R1 is bounded by the second circumferential wall 413 and the master piston 43, and a servo chamber Rs is bounded by the second circumferential wall 413, the first annular wall 414, and the master piston 43. The master chamber Rm is located near the front end of the master cylinder 31. The first fluid chamber R1 is located downstream of the master chamber Rm. The servo chamber Rs is located downstream of the first fluid chamber R1. Within the master cylinder 41, the master chamber Rm, the first fluid chamber R1, and the servo chamber Rs are not interconnected.

[0017] The cover cylinder 42 of the master cylinder 31 comprises a tubular third circumferential wall 421 and a second annular wall 422, which extends from a rear end of the third circumferential wall 421 toward an axis of the third circumferential wall 421. The third circumferential wall 421 is attached to the first annular wall 414 such that its axis coincides with the axis of the second circumferential wall 413 of the master cylinder 41. The second annular wall 422 is provided with a hole into which a rear end section of the inlet piston 44, described later, is inserted.

[0018] In the cover cylinder 42, a second fluid chamber R2 is formed by the first annular wall 414 of the main cylinder 41, the third circumferential wall 421, and the inlet piston 44. In the cover cylinder 42, a third fluid chamber R3 is bounded by the third circumferential wall 421, the second annular wall 422, and the inlet piston 44. In the master cylinder 31, the second fluid chamber R2 is located downstream of the servo chamber Rs. In the master cylinder 31, the third fluid chamber R3 is located downstream of the second fluid chamber R2. The second fluid chamber R2 and the third fluid chamber R3 are not connected to each other within the cover cylinder 42.

[0019] The master piston 43 is housed in the master cylinder 31 in surface contact with an inner circumferential surface of the first circumferential wall 412, an inner circumferential surface of the second circumferential wall 413, and an inner circumferential surface of the first annular wall 414 of the main cylinder 41. When the master piston 43 moves in an axial direction, it therefore slides on the inner circumferential surface of the first circumferential wall 412, the inner circumferential surface of the second circumferential wall 413, and the inner circumferential surface of the first annular wall 414. The rear end section of the main piston 43 projects further rearward relative to the first annular wall 414 and is located in the second fluid chamber R2.

[0020] The input piston 44 is housed in the master cylinder 31 in surface contact with an inner circumferential surface of the third circumferential wall 421 and an inner circumferential surface of the second annular wall 422 of the cover cylinder 42. As the input piston 44 moves axially, it slides on the inner circumferential surface of the third circumferential wall 421 and the inner circumferential surface of the second annular wall 422. The rear end section of the input piston 44 projects further rearward relative to the second annular wall 422. The brake actuating element 21 is coupled to the rear end section of the input piston 44. Therefore, the input piston 44 moves in a direction of approach to the master piston 43 according to an actuation amount of the brake actuating element 21. Furthermore, a gap is formed in the second fluid chamber R2 between the input piston 44 and the master piston 43.

[0021] The master spring 45 is installed in the master chamber Rm of the main cylinder 41. The main spring 45 pushes the main piston 43 backwards. Therefore, the main spring 45 is elastically compressed when the master piston 43 moves forwards.

[0022] The inlet spring 46 is located in the second fluid chamber R2 of the cover cylinder 42. The inlet spring 46 pushes the inlet piston 44 backwards. Therefore, the inlet spring 46 is elastically compressed when the inlet piston 44 moves forwards.

[0023] In the master cylinder 31, the master chamber Rm is connected to the reservoir tank 24. In particular, a section near the rear end of the master chamber Rm is connected to the reservoir tank 24 via an opening formed in the first circumferential wall 412 of the master cylinder 41. When the main piston 43 extends from a Fig. In the starting position illustrated in Figure 1, the master chamber Rm and the reservoir tank 24 are not connected. Consequently, the hydraulic pressure in the master 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 is moved forward by the hydraulic pressure in the servo chamber Rs. Accordingly, the hydraulic pressure in the master chamber Rm increases.

[0024] The master chamber Rm and the brake actuator 23 are connected via a first flow path 331. This means that the first flow path 331 connects some of the multiple wheel cylinders 11 and the master chamber Rm. Specifically, the first flow path 331 connects the wheel cylinders 11 for wheels FL and FR, which correspond to a second wheel cylinder, and the master chamber Rm. The first fluid chamber R1 and the second fluid chamber R2 are connected via a second flow path 332. Furthermore, the third fluid chamber R3 is connected to the reservoir 24 via a third flow path 333. Thus, when the input piston 44 moves forward, brake fluid is supplied from the reservoir 24 to the third fluid chamber R3. Conversely, when the input piston 44 moves backward, the brake fluid is discharged from the third fluid chamber R3 into the reservoir 24.The third flow path 333 connects the reservoir tank 24 and the second flow path 332.

[0025] A first control valve 341 is located in a section of the second flow path 332 between a connection point with the third fluid path 333 and the second fluid chamber R2. The first control valve 341 is a normally closed electromagnetic valve. The third flow path 333 is equipped with a second control valve 342. The second control valve 342 is a normally open electromagnetic valve. When the control unit 100 of the brake device 20 is in operation, the first control valve 341 opens and the second control valve 342 closes.

[0026] On the other hand, the stroke simulator 32 provided in the master device 30, together with the master cylinder 31, generates a reaction force corresponding to the actuation amount of the brake actuating element 21. The stroke simulator 32 is located between the first fluid chamber R1 and the first control valve 341 in the second flow path 332. The stroke simulator 32 includes, for example, a piston (not illustrated) that is biased by a spring from a rear surface. In this case, the stroke simulator 32 generates pressure in the brake fluid in response to the displacement of the piston when the internal piston is moved against the spring bias by the brake fluid flowing in from the second flow path 332.In particular, when the input piston 44 is moved forward by actuation of the brake actuating element 21 in a state in which the first control valve 341 is open and the second control valve 342 is closed, the brake fluid flows into the stroke simulator 32. This causes the stroke simulator 32 to generate the same pressure in the second fluid chamber R2 and the first fluid chamber R1, which are connected by the second flow path 332. <Konfiguration des Bremsabschnitts 50>

[0027] Next, a configuration of the brake section 50 is described. The brake section 50 includes an electric cylinder 51. The brake section 50 can control hydraulic pressure in the plurality of wheel cylinders 11 by actuating the electric cylinder 51.

[0028] The brake section 50 comprises a fourth flow path 54, a fifth flow path 55, and a sixth flow path 58. The fourth flow path 54 connects the electric cylinder 51 and the reservoir tank 24. The sixth flow path 58 connects the brake actuator 23 and the electric cylinder 51. That is, the sixth flow path 58 is a flow path that connects some of the multiple wheel cylinders 11 and the electric cylinder 51. Specifically, the sixth flow path 58 connects the wheel cylinders 11 for wheels RL and RR, corresponding to a first wheel cylinder, and the electric cylinder 51. The fifth flow path 55 connects the servo chamber Rs of the master cylinder 31 and the sixth flow path 58. The electric cylinder 51 is located between the fourth flow path 54 and the sixth flow path 58.The fourth flow path 54 is connected to an input port 515 of the electric cylinder 51. The sixth flow path 58 is connected to an output port 516 of the electric cylinder 51.

[0029] The brake section 50 comprises a release flow path 56 and a release valve 57. The release valve 57 is located in the release flow path 56. The release flow path 56 is a flow path that connects the reservoir tank 24 and the wheel cylinder 11 to bypass the electric cylinder 51. Hereinafter, the two ends of the flow path 56 are referred to as a first and a second section. The first end section of the flow path 56 is connected to the fourth flow path 54. The second end section of the flow path 56, on the other hand, is connected to the sixth flow path 58. Specifically, the release flow path 56 connects a section between the reservoir tank 24 and the inlet port 515 in the fourth flow path 54 and a section between the outlet port 516 and the brake actuator 23 in the sixth flow path 58.The release valve 47 is a normally closed electromagnetic valve that opens and closes the release flow path 56. That is, the release flow path 56 is closed while the control of the opening of the release valve 57 is not executed. <Konfiguration des elektrischen Zylinders 51>

[0030] The following describes a configuration of the electric cylinder 51. The electric cylinder 51 comprises a cylinder 511, a piston 512, a first electric motor 513, and a conversion mechanism 514. The piston 512 is slidably provided within the cylinder 511. The first electric motor 513 is a power source for the electric cylinder 51. The conversion mechanism 514 converts a rotary motion from the output of the first electric motor 513 into a linear motion of the piston 512.

[0031] Inside cylinder 511, a hydraulic chamber Re, into which the brake fluid is introduced, is bounded by a circumferential wall of the cylinder 511 and the piston 512. The position of the piston 512 within the cylinder 511 can be changed by the drive of the first electric motor 513. Hereinafter, a direction of movement of the piston 512 for reducing the volume of the hydraulic chamber Re is referred to as the "forward direction Za," and a direction opposite to the forward direction Za is referred to as the "retraction direction Zb." The retraction direction Zb is a direction of movement of the piston 512 for increasing the volume of the hydraulic chamber Re. Hereinafter, the end of a movable range of the piston 512 within the cylinder 511 in the retraction direction Zb is referred to as the "retraction limit position."

[0032] The inlet port 515 and the outlet port 516 are formed in the circumferential wall of the cylinder 511 as connecting openings between the hydraulic chamber Re and the outside world. A through-bore 517 is formed in the piston 512. The through-bore 517 is located at a position that allows a connection between the inlet port 515 and the hydraulic chamber Re when the piston 512 is in its retraction limit position. Thus, when the piston 512 is in its retraction limit position, the hydraulic chamber Re of the cylinder 511 is connected to the fourth flow path 54 via the inlet port 515 and the through-bore 517. That is, the hydraulic chamber Re of the cylinder 511 is connected to the reservoir tank 24 via the inlet port 515 and the through-bore 517.The inlet port 515 opens when the piston 512 is in its retraction limit position and is closed by the piston 512 when it moves from the retraction limit position in the forward direction Za. Thus, when the inlet port 515 is closed by the piston 512, the hydraulic pressure in the hydraulic chamber Re increases as the piston 512 moves in the forward direction Za. The inlet port 515 therefore serves as an inlet for brake fluid from the reservoir tank 24 into the hydraulic chamber Re.

[0033] The outlet port 516 of the cylinder 511 is connected to the brake actuator 23 and the fifth flow path 55 via the sixth flow path 58. The outlet port 516 is always open, regardless of the position of the piston 512. Therefore, if the inlet port 515 is closed by the piston 512, when the piston 512 moves in the forward direction Za, the brake fluid in the hydraulic chamber Re is discharged from the outlet port 516 to the outside of the cylinder 511. The outlet port 516 thus serves as an outlet for the brake fluid from the hydraulic chamber Re. <Konfiguration des Bremsstellglieds 23>

[0034] Next, a configuration of the brake actuator 23 is described. The brake actuator 23 is capable of individually controlling the hydraulic pressure in the plurality of wheel cylinders 11. The brake actuator 23 comprises two pumps 631 and 632, which use a second electric motor 64 as a power source.

[0035] The brake actuator 23 can increase the hydraulic pressure in the wheel cylinder 11 without increasing the hydraulic pressure controlled by the brake section 50. This means that the brake device 20 has a redundant configuration, with the brake section 50 located on an upstream side and the brake actuator 23 on a downstream side.

[0036] The brake actuator 23 comprises two hydraulic circuits, i.e., a first hydraulic circuit 611 and a second hydraulic circuit 612. The two wheel cylinders 11 for wheels FL and FR are connected to the first hydraulic circuit 611. The two wheel cylinders 11 for wheels RL and RR are connected to the second hydraulic circuit 612.

[0037] The first hydraulic circuit 611 is connected to the reservoir tank 24 via the first flow path 331 and the master chamber Rm. In the first circuit 611, a first differential pressure control valve 621, which is a normally open electromagnetic linear valve, is provided in a fluid path that connects a connection point to the first flow path 331 and the wheel cylinder 11.

[0038] The second hydraulic circuit 612 is connected to the reservoir tank 24 via the fourth flow path 54, the electric cylinder 51, and the sixth flow path 58. In the second circuit 612, a second differential pressure control valve 622, which is a normally open electromagnetic linear valve, is provided in a fluid path that connects a junction point to the sixth flow path 58 and the wheel cylinder 11.

[0039] Pump 631 is located in the first hydraulic circuit 611. Pump 631 supplies brake fluid to a fluid path connecting the first differential pressure control valve 621 and the wheel cylinder 11. Pump 632 is located in the second hydraulic circuit 612. Pump 632 supplies brake fluid to a fluid path connecting the second differential pressure control valve 622 and the wheel cylinder 11.

[0040] In the first hydraulic circuit 611, the same number of ports 65a and 65b as the wheel cylinders 11 connected to the first hydraulic circuit 611 are provided closer to the wheel cylinder 11 than the first differential pressure control valve 621. Similarly, in the second hydraulic circuit 612, the same number of ports 65c and 65d as the wheel cylinders 11 connected to the second hydraulic circuit 612 are provided closer to the wheel cylinder 11 than the second differential pressure control valve 622. Each of the plurality of ports 65a to 65d is provided with a holding valve 66, which closes when an increase in hydraulic pressure in the wheel cylinder 11 is limited, and a pressure reducing valve 67, which opens when the hydraulic pressure is reduced. That is, the holding valve 66 is located in the fluid path closer to the wheel cylinder 11 than the first differential pressure control valve 621 and the second differential pressure control valve 622.The multitude of holding valves 66 are normally open electromagnetic valves, and the multitude of pressure reducing valves 67 are normally closed electromagnetic valves.

[0041] The first hydraulic circuit 611 and the second hydraulic circuit 612 are connected to reservoirs 681 and 682, respectively, in which the brake fluid flowing from the wheel cylinder 11 via the pressure reducing valve 67 is temporarily stored when the pressure reducing valve 67 is open. The multiple reservoirs 681 and 682 are connected to the pumps 631 and 632 via flow paths 691 and 692.

[0042] Reservoir 681 is connected via a tank-side flow path 701 to a fluid path that connects the first differential pressure control valve 621 and the master chamber Rm. Reservoir 682 is connected via a tank-side flow path 702 to a fluid path that connects the connection point to the sixth flow path 58 and the second differential pressure control valve 622 in the second hydraulic circuit 612.

[0043] The multiple pumps 631 and 632 can pump the brake fluid from reservoir tank 24 via reservoirs 681 and 682. The multiple pumps 631 and 632 discharge the pumped brake fluid into fluid paths between the first differential pressure control valve 621 and the second differential pressure control valve 622 and the holding valves 66. Hereinafter, the fluid paths between the fluid paths and pumps 631 and 632 are referred to as intermediate fluid paths 711 and 712, respectively. <Erfassungssystem der Bremsvorrichtung 20>

[0044] The brake device 20 includes a detection system with a variety of sensors. The variety of sensors that make up the detection system includes a stroke sensor SE1, a rotary angle sensor SE2, a master hydraulic pressure sensor 351, an input hydraulic pressure sensor 352, and a control pressure sensor 353.

[0045] The stroke sensor SE1 detects the actuation amount of the brake actuation element 21. The rotation angle sensor SE2 detects a rotation angle of the first electric motor 513, which is an energy source for the electric cylinder 51. The rotation angle of the first electric motor 513, based on a detection value from the rotation angle sensor SE2, is referred to as the "motor rotation angle θmt".

[0046] The master hydraulic pressure sensor 351 detects the hydraulic pressure in the master chamber Rm. The master hydraulic pressure sensor 351 is, for example, provided in the first flow path 331. The hydraulic pressure in the master chamber Rm, based on a reading from the master hydraulic pressure sensor 351, is referred to as the "master pressure".

[0047] The hydraulic pressure sensor 352 detects the hydraulic pressure in the second fluid chamber R2. For example, the hydraulic pressure sensor 352 is located between the first control valve 341 and the second fluid chamber R2 in the second flow path 332. The hydraulic pressure in the second fluid chamber R2, based on a detection value from the hydraulic pressure sensor 352, is referred to as the "hydraulic pressure at the inlet".

[0048] The control pressure sensor 353 is a hydraulic pressure sensor that detects the hydraulic pressure of the brake fluid discharged by the electric cylinder 51. The control pressure sensor 353 is, for example, located near the output port 516 of the electric cylinder 51. (Illustrated as an example.) Fig. 1. A configuration in which the control pressure sensor 353 is connected between the release valve 57 and the outlet port 516 in the release flow path 56. The discharged hydraulic pressure of the electric cylinder 51, based on a reading from the control pressure sensor 353, is referred to as the "control pressure Psc". In this embodiment, the control pressure sensor 353 corresponds to a hydraulic pressure sensor that detects the hydraulic pressure of the brake fluid discharged by the electric cylinder 51. <Konfiguration der Steuerungseinheit 100>

[0049] The brake device 20 includes the control unit 100. The control unit 100 is, for example, an electronic device. In this case, the control unit 100 includes a CPU and memory. The memory stores a control program to be executed by the CPU. The control unit 100 receives detection signals from the sensors that form the detection system of the brake device 20. The control unit 100 controls the operation of the hydraulic pressure generating device 22 and the brake actuator 23 by having the CPU execute the control program. Specifically, the control unit 100 controls the first control valve 341, the second control valve 342 and the release valve 57 of the hydraulic pressure generating device 22, as well as the first electric motor 513 of the electric cylinder 51. The control unit 100 also controls the various electromagnetic valves (621, 622, 66 and 77) of the brake actuator 23 and the second electric motor 64. <Antriebssteuerung für den elektrischen Zylinder 51>

[0050] Next, the drive control for the electric cylinder 51, performed by the control unit 100, is described. When the driver starts the vehicle, energy is supplied to the brake device 20. The control unit 100 is started by the supply of energy.

[0051] After startup, the control unit 100 executes a drive preparation process for the electric cylinder 51. During this process, the control unit 100 first instructs the first electric motor 513 of the electric cylinder 51 to rotate in a specific direction to move the piston 512 in the retraction direction Zb. As this command is continued, the piston 512 moves in the retraction direction Zb until it reaches the retraction limit position. When the piston 512 reaches the retraction limit position, the load on the first electric motor 513 increases, since the movement of the piston 512 is mechanically limited. Based on an increase in the current value of the first electric motor 513 with the increase in load, the control unit 100 confirms that the piston 512 has reached the retraction limit position.When the attainment of the retraction limit position is confirmed, the control unit 100 temporarily stops the rotation of the first electric motor 513. The control unit 100 then instructs the first electric motor 513 to rotate by a predetermined amount Xm in one direction to move the piston 512 in the forward direction Za. Accordingly, the piston 512 moves forward Za by a predetermined amount from the retraction limit position. The position of the piston 512 at this point is subsequently referred to as the ready position. A movement position of the piston 512 in which the inlet port 515 is switched between an open and a closed state by the piston 512 is referred to as the pressurization start position.The predetermined rotation amount Xm is set such that the ready position is a position shifted in the retraction direction Zb relative to the pressurization start position and in the forward direction Za relative to the retraction limit position. To improve the response of the braking device 20, it is desirable to set the ready position to a position close to the pressurization start position in a range where the input port 515 is reliably open.

[0052] The control unit 100 then determines, based on a detection signal from the stroke sensor SE1 or similar, whether a braking request exists or not. If it is determined that there is no braking request, the control unit 100 holds the piston 512 of the electric cylinder 51 in the ready position. If, however, it is determined that there is a braking request, the control unit 100 activates the first electric motor 513 to move the piston 512 in the forward direction Za. When the piston 512 moves from the ready position into the forward direction Za, the input port 515 is closed by the piston 512. The brake fluid in the hydraulic chamber Re is discharged from the output port 516 by the pressure of the piston 512. In this way, the brake device 20 supplies the brake fluid to the wheel cylinders 11 of the wheels FL, FR, RL, and RR to generate a braking force.If the request is released during the generation of the braking force, the control unit 100 activates the first electric motor 513 to move the piston 512 in the retraction direction Zb into the ready position. <Ausgangskalibrierung für Steuerdrucksensor 353>

[0053] As described above, the brake device 20 includes the control pressure sensor 353, which detects the control pressure Psc, corresponding to the hydraulic pressure of the brake fluid discharged by the electric cylinder 51. The control unit 100 calculates the control pressure Psc based on an output from the control pressure sensor 353. Hereinafter, the control pressure Psc calculated by the control unit 100 based on the output of the control pressure sensor 353 is referred to as the detected control pressure Psc value.

[0054] The output characteristics of the control pressure sensor 353 are temperature-dependent. The measured value of the control pressure Psc can deviate from the actual value due to a temperature-related change in the output characteristics of the control pressure sensor 353. In the brake device 20 according to the exemplary embodiment, an output calibration for the control pressure sensor 353 is performed to correct the deviation of the measured value of the control pressure Psc resulting from such a change in the output characteristics.

[0055] Fig. Figure 2 illustrates a flowchart of a calibration performed by the control unit 100 to carry out the output calibration for the control pressure sensor 353. The control unit 100 performs the same routine repeatedly in each predetermined control cycle during the operation of the device 20.

[0056] When this routine is started, the control unit 100 first determines in step S100 whether a braking request exists. For example, if the detected value of the actuation amount of the brake actuator 21, detected by the stroke sensor SE1, is not "0", the control unit 100 determines that a control request exists.

[0057] If a braking request is received (S100: YES), control unit 100 proceeds to step S110. In step S110, control unit 100 sets the value of a calibration flag F to "0" and then terminates the processing of this routine in the current control cycle. The calibration request flag F indicates that output calibration for the control pressure sensor 353 is performed when the value is "1".

[0058] If, however, there is no braking request (S100: NO), the control unit 100 continues the process up to step S120. In step S120, the control unit 100 determines whether the value of flag F for the calibration request is "1". If the value of flag F for the calibration request is "0" (NO), the control unit 100 proceeds to step S130, and if the value is "1" (YES), the control unit 100 proceeds to step S160.

[0059] As processing progresses to step S130, the control unit 100 determines in step S130 whether there is a deviation in the control pressure Psc reading received from the control pressure sensor 353. If there is no braking request, the control unit 100 controls the first electric motor 513 so that the piston 512 of the electric cylinder 51 is in the ready position. Since the input port 515 is open in the ready position, the hydraulic chamber Re of the electric cylinder 51 is connected to the reservoir tank 24. At this point, the control pressure Psc has a value equivalent to atmospheric pressure. Therefore, the control unit 100 determines that a deviation in the control pressure Psc reading exists if the magnitude of the deviation from the atmospheric pressure equivalent is equal to or greater than a predetermined threshold.

[0060] If it is determined that there is no deviation in the measured value of the control pressure Psc (S130: NO), the control unit 100 terminates the current processing of this routine. However, if it is determined that there is a deviation in the measured value of the control pressure Psc (S130: YES), the control unit 100 continues processing to step S140.

[0061] In step S140, the control unit 100 sets the value of flag F for the calibration request to "1". In the subsequent step S150, the control unit 100 instructs piston 512 to retract from its ready position. That is, the control unit 100 instructs the first electric motor 513 to move piston 512 to a position that is offset in the retraction direction Zb relative to the ready position. After the command, the control unit 100 terminates the processing of this routine in the current control cycle.

[0062] If, however, the process continues to step S160, the control unit 100 determines in step S160 whether the retraction of piston 512, as instructed in step S150, is complete. For example, if the rotational speed of the first electric motor 513 reaches a predetermined value after the command in step S150, the control unit 100 determines that the retraction of piston 512 is complete. If the retraction of piston 512 is not complete (NO), the control unit 100 terminates the processing of this routine in the current control cycle. If, on the other hand, the retraction of piston 512 is complete (YES), the control unit 100 continues processing to step S170.

[0063] In step S170, the control unit 100 performs the output calibration for the control pressure sensor 353. For example, the control unit 100 receives a deviation value of the output of the control pressure sensor 353 based on an average value of the output over a predetermined period. The control unit 100 then corrects the output of the control pressure sensor 353 by the amount of the deviation. In this embodiment, the output calibration for the control pressure sensor 353 requires a large number of control cycles.

[0064] The control unit 100 then determines in step S180 whether the output calibration for the control pressure sensor 353 is complete in the current control cycle. If the output calibration is not complete (NO), the control unit 100 terminates the processing of this routine in the current control cycle. If, however, the output calibration is complete (YES), the control unit 100 sets the value of flag F for the calibration request in step S110 to "0" and then terminates the processing of this routine in the current control cycle. <Operation und Effekt der Ausführungsbeispiele>

[0065] The functionality and effect of the exemplary embodiment are described. If a deviation in the output of the control pressure sensor 353 is detected during operation of the brake device 20, the control unit 100 performs the output calibration for the control pressure sensor 353. This output calibration is performed under the premise that the input port 515 of the electric cylinder 51 is open.

[0066] After the requested braking action is released, the control unit 100 controls the first electric motor 513 to retract the piston 512 to the ready position. However, it is conceivable that the piston 512 remains in a position shifted forward relative to the ready position (Za) without fully returning to the ready position. In this case, since the input port 515 is not open, residual pressure builds up in the hydraulic chamber (Re). In such a state, where residual pressure is generated, the output calibration for the control pressure sensor 353 cannot be performed correctly.

[0067] On the other hand, in the exemplary embodiment, when the deviation in the output of the control pressure sensor 353 is confirmed, the control unit 100 first instructs the first electric motor 513 to move the piston 512 in the retraction direction Zb relative to the ready position. Then, the control unit 100 performs the output calibration for the control pressure sensor 353 based on an output from the control pressure sensor 353 after the command. That is, after instructing the first electric motor 513 to move the piston 512 in the retraction direction Zb relative to the ready position, the control unit 100 performs the calibration processing to execute the output calibration for the control pressure sensor 353.In such a case, even if the piston 512 is stopped in a forward-moving position Za relative to the ready position before the output calibration is performed, and residual pressure is generated in the hydraulic chamber Re, there is a high probability that the input port 515 will open during the output calibration. Therefore, it is less likely that the output calibration will be performed incorrectly in a state where the input port 515 is not open. Thus, according to the exemplary embodiment, the brake device 20 has the effect that the detection accuracy of the control pressure sensor 353 can be easily maintained even if the output characteristics change.

[0068] Since the electric cylinder 51 is controlled in a state where the input port 515 is open when no braking force is required, the control pressure Psc has a value equivalent to atmospheric pressure. Therefore, if the hydraulic pressure reading from the control pressure sensor 353 at this time deviates from the value equivalent to atmospheric pressure, it can be determined that there is a deviation in the output of the control pressure sensor 353. Conversely, the control unit 100 performs calibration processing if the difference between the hydraulic pressure reading received by the hydraulic pressure sensor 353 when no braking force is required and the value equivalent to atmospheric pressure is equal to or greater than a threshold value.Therefore, if there is a deviation in the output of the control pressure sensor 353 due to the ambient temperature or the like during the operation of the brake device 20, the deviation can be quickly corrected.

[0069] If the generation of a braking force is requested during the execution of the calibration process, the control unit 100 immediately stops the calibration process at that time. Therefore, it is less likely that the generation of a braking force will be delayed by the execution of the calibration process.

[0070] The control unit 100 retracts the piston 512 to a retraction limit during the processing of the drive preparation for the electric cylinder 51. The control unit 100 also performs the output calibration for the control pressure sensor 353 if the piston 512 moves in the retraction direction Zb relative to the ready position during the drive preparation process. (Second example)

[0071] A braking device according to a second embodiment is described below with reference to Fig. 3 described in detail. <Ausgangskalibrierung für Steuerdrucksensor 353>

[0072] The hardware configuration of the braking device according to the exemplary embodiment is the same as in Fig. 1. The braking device according to the exemplary embodiment differs from the device according to the first exemplary embodiment in the content of the calibration process.

[0073] Fig. Figure 3 illustrates a flowchart of a calibration performed by the control unit 100 of the brake device 20 according to the exemplary embodiment. The control unit 100 performs the same routine repeatedly in each predetermined control cycle during the operation of the device 20.

[0074] When this routine starts, the control unit 100 first determines in step S200 whether a braking request exists. If a braking request exists (YES), the control unit 100 controls the process to step S210; if no braking request exists (NO), it controls the process to step S230.

[0075] In step S210, control unit 100 sets the value of flag F for the calibration request to "0". In step S220, control unit 100 instructs the release valve 57 to close and then terminates the processing of this routine in the current control cycle.

[0076] On the other hand, in step S230, the control unit 100 determines whether the value of flag F for calibration is "1". If the value of flag F for the calibration request is "0" (NO), the control unit 100 continues with processing in step S240, and if the value is "1" (YES), the control unit 100 continues with processing in step S270.

[0077] In step S240, the control unit 100 determines whether there is a deviation in a control pressure Psc measurement value received from the control pressure sensor 353. If it is determined that there is no deviation in the control pressure Psc measurement value (S240: NO), the control unit 100 terminates the current processing of this routine. If, however, it is determined that there is a deviation in the control pressure Psc measurement value (S240: YES), the control unit 100 advances the processing to step S250.

[0078] In step S250, the control unit 100 sets the value of the flag for the calibration request F to "1". After instructing the opening of the release valve 57 in the subsequent step S260, the control unit 100 terminates the processing of this routine in the current control cycle.

[0079] On the other hand, in step S270, the control unit 100 performs the calibration processing as in step S170. Fig. 2. In the subsequent step S280, the control unit 100 determines whether the calibration processing is complete. If the calibration processing is complete (YES), the control unit 100 proceeds to step S210 described above, and if the calibration processing is not complete (NO), the control unit 100 terminates the processing of this routine in the current control cycle. <Operation und Effekt der Ausführungsbeispiele>

[0080] The functionality and effect of the exemplary embodiment are described. In this embodiment as well, the control unit 100 performs the output calibration for the control pressure sensor 353 when a deviation in the output of the control pressure sensor 353 is confirmed during operation of the brake device 20. During the output calibration, the control unit 100 opens the release valve 57. When the release valve 57 opens, the output port 516 of the electric cylinder 51 and the reservoir tank 24 are connected via the release flow path 56. As a result, the control pressure Psc has a value equivalent to atmospheric pressure, regardless of whether the input port 515 of the electric cylinder 51 is open. Therefore, according to this embodiment, the brake device 20 also has the effect of easily maintaining the detection accuracy of the control pressure sensor 353 with respect to changes in its output.When the calibration processing is complete, and if the generation of a braking force is requested during the calibration processing, the control unit 100 quickly closes the release valve 57. (Further examples)

[0081] The above embodiments can be modified and implemented as follows. Within a technically consistent range, the embodiment and the following modifications can also be combined.

[0082] In step S150 in Fig. 2. The retraction of piston 512 to the retraction limit position can be instructed. In this case, the determination of the completion of the retraction can be made in step S160. Fig. 2 based on an increase in the current value of the first electric motor 513.

[0083] The content of the calibration processing in step S170 in Fig. 2 and step S270 in Fig. 3 can be changed as needed. For example, the calibration process can be performed by obtaining a deviation of the output of the control pressure sensor 353 from an instantaneous value of the output.

[0084] The initial calibration for the master hydraulic pressure sensor 351 can be performed together with the initial calibration for the control pressure sensor 353 via the calibration routine in Fig. 2 or Fig. 3 will be executed. The configuration of the brake device 20 can be determined from the one in Fig. 1 may differ as long as the brake device 20 includes the electric cylinder 51 and a hydraulic pressure sensor that detects the hydraulic pressure of the brake fluid discharged by the electric cylinder 51.

[0085] The brake section 50 of the first embodiment cannot include the release flow path 56 and the release valve 57. In this case, the release flow path 56 is located in Fig.1 installed control pressure sensor 353 preferably in the fifth flow path 55 or in a section between the second differential pressure control valve 622 and the output port 516 of the electric cylinder 51 in the sixth flow path 58.

[0086] During the calibration process for the control pressure sensor 353, it can be selected, according to a predetermined condition, whether the control pressure Psc is equivalent to atmospheric pressure by using the piston 512 or the release valve 57. For example, while driving, the calibration process for the control pressure sensor 353 is performed by setting the control pressure Psc equivalent to atmospheric pressure using the release valve 57. Conversely, the calibration process for the control pressure sensor 353 can be performed when the vehicle is stationary by setting the control pressure Psc equivalent to atmospheric pressure using the piston 512.

[0087] The control unit 100 can be implemented as a circuit comprising one or more processors that operate according to a computer program, one or more dedicated hardware circuits, such as dedicated hardware that performs part of the processing of various processing types, or a combination thereof. Examples of dedicated hardware include an application-specific integrated circuit (ASIC). The processor comprises a CPU and memory, such as RAM and ROM, and the memory stores program code or instructions configured to cause the CPU to perform processing. The memory, i.e., a storage medium, comprises any available medium accessible to a general-purpose or dedicated computer. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2009-137376A

[0003]

Claims

[1] Brake device, with: a reservoir tank (24) configured to store brake fluid; an electric cylinder (51) configured to discharge the brake fluid by moving a piston (512) in the cylinder (51) in response to a drive by an electric motor (513); a hydraulic pressure sensor (351) configured to detect the hydraulic pressure of the brake fluid discharged through the electric cylinder (51); and a control unit (100) configured to control the electric motor (513), wherein the braking device is configured to generate a braking force on a wheel by supplying the brake fluid to a wheel cylinder (11) in response to the discharge of the brake fluid from the electric cylinder (51), wherein the electric cylinder (51) comprises a hydraulic chamber (Re) defined by a circumferential wall of the cylinder and the piston, an inlet port (515) which provides an inlet for the brake fluid from the reservoir tank (24) into the hydraulic chamber (Re), and an outlet port (516) which provides an outlet for the brake fluid from the hydraulic chamber (Re), the electric cylinder (51) is configured such that, if a direction of movement of the piston (512) for reducing a volume of the hydraulic chamber (Re) is defined as a forward direction, a direction opposite to the forward direction is defined as a retraction direction, and a furthest position in the retraction direction in a movable area of ​​the piston (512) is defined as a retraction limit position, the input port (515) is open when the piston (512) is at the retraction limit position, and when the piston (512) is moved from the retraction limit position in the forward direction and the input port (515) is closed, the hydraulic pressure in the hydraulic chamber (Re) increases and the brake fluid is discharged from the output port (516). the control unit (100) holds the piston in a ready position, which is set between a position in which the input port (515) switches between a closed state and an open state, and the retraction limit position when brake force generation is not requested, and controls the electric motor (513) to move the piston (512) from the ready position in the forward direction when brake force generation is requested, and The control unit (100) performs a calibration processing operation of executing an output calibration of the hydraulic pressure sensor (351) after the electric motor (513) is instructed to move the piston (512) in the retraction direction relative to the ready position. [2] Brake device, with: a reservoir tank (24) configured to store brake fluid; an electric cylinder (51) configured to discharge the brake fluid by moving a piston (512) in the cylinder (51) in response to a drive by an electric motor (513); a hydraulic pressure sensor (351) configured to detect the hydraulic pressure of the brake fluid discharged through the electric cylinder (51); and a control unit (100) configured to control the electric motor (513), wherein the braking device is configured to generate a braking force on a wheel by supplying the brake fluid to a wheel cylinder (11) in response to a discharge of the brake fluid from the electric cylinder (51), wherein the electric cylinder (51) comprises a hydraulic chamber (Re) defined by a circumferential wall of the cylinder and the piston, an inlet port (515) which provides an inlet for the brake fluid from the reservoir tank (24) into the hydraulic chamber (Re), and an outlet port (516) which provides an outlet for the brake fluid from the hydraulic chamber (Re), the electric cylinder (51) is configured such that, if a direction of movement of the piston (512) for reducing a volume of the hydraulic chamber (Re) is defined as a forward direction, a direction opposite to the forward direction is defined as a retraction direction, and a furthest position in the retraction direction in a movable area of ​​the piston (512) is defined as a retraction limit position, the input port (515) is open when the piston is at the retraction limit position, and when the piston (512) is moved forward from the retraction limit position and the input port (515) is closed, the hydraulic pressure in the hydraulic chamber (Re) increases and the brake fluid is discharged from the output port (516). the brake device further comprises a release flow path (56) configured to establish a connection between the outlet port (516) and the reservoir tank (24) without passing through the hydraulic chamber (Re), and a release valve (57) configured to open and close the release flow path (56), the control unit (100) holds the piston (512) in a standby position, which is set between a position in which the input port (515) switches between a closed state and an open state, and the retraction limit position when brake force generation is not requested, and controls the electric motor (513) to move the piston (512) from the standby position in the forward direction when brake force generation is requested, and the control unit (100) performs a calibration processing by executing an output calibration for the hydraulic pressure sensor (351) in a state in which the release valve (57) is open. [3] Braking device according to claim 1 or 2, wherein the control unit (100) performs the calibration processing in a case where a difference between a detection value of the hydraulic pressure received by the hydraulic pressure sensor (351) when the generation of the braking force is not requested and a value equivalent to atmospheric pressure is equal to or greater than a threshold value. [4] Braking device according to claim 1 or 2, wherein the control unit (100) stops the calibration processing when the generation of the braking force is requested during the execution of the calibration processing.

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