Vehicle braking system

Abstract

To provide a vehicle braking device that is configured so that two braking units having a shared function can appropriately control rotation of an electric motor although element components that are individually designed for each wheel are reduced.SOLUTION: A vehicle braking device comprises first and second braking units 10L and 10R and a brake ECU 30. The braking units 10L and 10R have electric motors 14L and 14R that rotate in both normal and reverse directions, and circuit boards 20L and 20R provided with driving circuits 22 for generating driving currents for the electric motors 14L and 14R, respectively. The brake ECU 30 is configured to set a command signal which is outputted to the second braking unit 10R when commanding rotation in the normal direction (or in the reverse direction) of the electric motor 14R to a signal for rotating the electric motor 14L in the reverse direction (or in the normal direction) when the command signal is outputted to the first braking unit 10L.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a vehicle braking system. [Background technology]

[0002] Conventionally, electric braking devices such as that disclosed in Patent Document 1 are known as vehicle braking devices. The vehicle braking device in this document includes a braking unit provided on each wheel. Each braking unit generates braking force by pressing brake pads, which are friction materials, against a brake disc, which is a rotating body that rotates integrally with the wheel. Each braking unit includes an electric motor and a circuit board. The electric motor displaces the brake pads toward and away from the brake disc in response to rotation. The circuit board is provided with a control circuit for controlling the power supplied to each phase of the electric motor in response to commands from an external braking unit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-145370 Summary of the Invention [Problem to be solved by the invention]

[0004] A vehicle may have multiple wheels equipped with braking units that share the same functions. However, the relative positions of the brake discs and the braking units vary for each wheel. For example, the layout of each component in a braking unit will differ depending on the wheel, whether it is installed on the right wheel or the left wheel. Therefore, even if the braking units share the same functions, it may be necessary to design the components individually for each wheel. [Means for solving the problem]

[0005] A vehicle braking system that solves the above problem includes first and second brake units that generate a braking force for the vehicle by pressing a friction material against a rotating body that rotates integrally with the vehicle wheels, and a command unit. Each of the first and second brake units includes an electric motor that can rotate in a forward and reverse direction to displace the friction material toward or away from the rotating body, and a circuit board that has a plurality of terminals connected to power lines of the electric motor and is provided with an electric circuit for controlling the power supplied to each terminal based on a command signal input from the command unit. The command unit of the vehicle control device outputs a command signal to the first and second brake units that includes a command for the rotation direction of the electric motor, and is configured to output the command signal to the second brake unit so that, when the command signal is output to the first brake unit, the command for the electric motor of the first brake unit and the command for the electric motor of the second brake unit are opposite to each other.

[0006] As the first and second brake units share common components, the connection relationship between the electric motor's power lines and the terminals on the circuit board may not match between the first and second brake units. In such a case, if the circuit boards of both brake units control the electric motor in the same way, the electric motor of the second brake unit may rotate in the opposite direction to the electric motor of the first brake unit. The command unit of the vehicle braking system commands the second brake unit to rotate in the opposite direction to the rotation direction it was originally commanded to rotate. Therefore, even in such a case, the electric motors of both brake units can be properly controlled. In other words, it is possible to tolerate a mismatch in the connection relationship between the electric motor's power lines and the terminals on the circuit board between the first and second brake units. This makes it easier to share common components between multiple brake units. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a diagram schematically illustrating an overall configuration of an embodiment of a vehicle braking device; [Figure 2]FIG. 2 is an exploded perspective view of the electric motor and circuit board of the first brake unit. [Figure 3] FIG. 3 is a diagram showing the configuration of an electric circuit of a first braking unit. [Figure 4] FIG. 10 is an exploded perspective view of the electric motor and circuit board of the second brake unit. [Figure 5] FIG. 4 is a diagram showing the configuration of an electric circuit of a second braking unit. [Figure 6] FIG. 4 is a diagram showing a flow of processing relating to braking force control of a vehicle braking device. [Figure 7] 10 is a graph showing the relationship between the electrical angle of the electric motor of the first braking unit and the terminal current of the circuit board. [Figure 8] 10 is a graph showing the relationship between the electrical angle of the electric motor of the second braking unit and the terminal current of the circuit board. [Figure 9] This is a graph in which the horizontal axis of the graph in FIG. 7 is changed to "-θ2±180°". DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, a vehicle braking device according to one embodiment will be described with reference to FIGS. <Overall configuration of vehicle braking system> First, the overall configuration of the vehicle braking system will be described with reference to Fig. 1. As shown in Fig. 1, the vehicle braking system includes two braking units: a first braking unit 10L and a second braking unit 10R. The vehicle braking system also includes a brake ECU (Electronic Control Unit) 30 as a command unit.

[0009] The first brake unit 10L generates a braking force on the left rear wheel 11L by pressing a brake pad 13L against a brake disc 12L of the left rear wheel 11L of the vehicle. The second brake unit 10R generates a braking force on the right rear wheel 11R by pressing a brake pad 13R against a brake disc 12R of the right rear wheel 11R of the vehicle. The brake disc 12L is connected to the left rear wheel 11L, and the brake disc 12R is connected to the right rear wheel 11R so as to rotate integrally with the wheel. In this embodiment, the brake discs 12L and 12R correspond to rotating bodies that rotate integrally with the wheels. In this embodiment, the brake pads 13L and 13R correspond to friction materials. Both brake units 10L and 10R are supplied with power from the vehicle's battery 33 via the brake ECU 30.

[0010] Each of the brake units 10L and 10R includes an electric motor 14L, 14R, a reduction gear 15L, 15R, a linear motion conversion mechanism 16L, 16R, a piston 17L, 17R, and a circuit board 20L, 20R. In each of the brake units 10L, 10R, the electric motor 14L, 14R serves as a power source for generating braking force. In this embodiment, a three-phase AC synchronous motor having coils for three phases (U, V, and W) is used as the electric motor 14L, 14R. The reduction gear 15L, 15R reduces the rotation of the electric motor 14L, 14R and transmits it to the linear motion conversion mechanism 16L, 16R. The linear motion conversion mechanism 16L, 16R converts the rotation transmitted from the reduction gear 15L, 15R into linear motion. The circuit boards 20L and 20R are boards on which electric circuits for controlling the drive of the electric motors 14L and 14R are provided.

[0011] The power of the electric motors 14L, 14R, converted into linear motion by the linear motion conversion mechanisms 16L, 16R, is transmitted to the brake pads 13L, 13R via the pistons 17L, 17R. The braking units 10L, 10R thus convert the rotation of the electric motors 14L, 14R into linear motion and apply it to the brake pads 13L, 13R, generating a pressing force of the brake pads 13L, 13R against the brake discs 12L, 12R. This pressing force increases as the brake pads 13L, 13R move toward the brake discs 12L, 12R. On the other hand, this pressing force decreases as the brake pads 13L, 13R move away from the brake discs 12L, 12R. In the following description, rotation of the electric motors 14L, 14R in a direction that displaces the brake pads 13L, 13R toward the brake discs 12L, 12R will be referred to as "forward rotation" of the electric motors 14L, 14R. In contrast, rotation of the electric motors 14L, 14R in a direction that displaces the brake pads 13L, 13R away from the brake discs 12L, 12R will be referred to as "reverse rotation" of the electric motors 14L, 14R. The electric motors 14L, 14R can rotate in both the forward and reverse directions to displace the brake pads 13L, 13R toward or away from the brake discs 12L, 12R.

[0012] On the other hand, the brake ECU 30 is an electronic control unit for controlling the braking force of the vehicle. Detection signals from various sensors for detecting the driving conditions of the vehicle are connected to the brake ECU 30. Sensors that output detection signals to the brake ECU 30 include a pedal stroke sensor 31 that detects the amount of brake pedal operation by the vehicle driver, and a wheel speed sensor 32 that detects the wheel speed, which is the rotational speed of each wheel. Based on the detection signals from the various sensors, the brake ECU 30 determines the braking force to be generated in each of the brake units 10L, 10R. Then, the brake ECU 30 outputs a command signal to each of the brake units 10L, 10R to instruct them to generate the determined braking force.

[0013] <Connection between the electric motor 14L and the circuit board 20L in the first brake unit 10L> Next, with reference to FIGS. 2 and 3, the manner in which the electric motor 14L and the circuit board 20L in the first brake unit 10L are connected will be described.

[0014] As shown in Figure 2, a rotor 19 formed by a permanent magnet is attached to the rotating shaft 18 of the electric motor 14L so as to rotate integrally therewith. The electric motor 14L also has three connection terminals CU, CV, and CW connected to the U-phase, V-phase, and W-phase coils of the electric motor 14L, respectively. The connection terminal CU is connected to the U-phase coil, the connection terminal CV is connected to the V-phase coil, and the connection terminal CW is connected to the W-phase coil. These three connection terminals CU, CV, and CW are arranged in series on the radial outside of the rotor 19, with the connection terminal CU in the center.

[0015] On the other hand, the circuit board 20L is provided with a microcontroller 21, a drive circuit 22, an input terminal 23, and three output terminals CB1, CB2, and CB3. The input terminal 23 is a terminal for electrically connecting the circuit board 20L to the brake ECU 30. The output terminals CB1 to CB3 are terminals for connecting to the connection terminals CU, CV, and CW of the electric motor 14L, respectively. The drive circuit 22 is an electric circuit for generating a drive current for the electric motor 14L. The microcontroller 21 drives the drive circuit 22 based on a command signal from the brake ECU 30 to control the power supplied to each of the output terminals CB1 to CB3.

[0016] The circuit board 20L is also provided with a detection section 25. The detection section 25 is provided with an MR sensor element whose electrical resistance changes in response to changes in the surrounding magnetic field. In the following description, the surface of the circuit boards 20L, 20R on which the detection unit 25 is installed, i.e., the installation surface of the detection unit 25, will be referred to as the front surface F of the circuit boards 20L, 20R. The surface of the circuit boards 20L, 20R opposite the installation surface of the detection unit 25 will be referred to as the back surface B of the circuit boards 20L, 20R. In this embodiment, the microcontroller 21 and the drive circuit 22 are also installed on the front surface F of the circuit boards 20L, 20R. In the first brake unit 10L, the circuit board 20L is installed with the back surface B facing the electric motor 14L. In this first brake unit 10L, the connection terminal CV is connected to the output terminal CB1, the connection terminal CU is connected to the output terminal CB2, and the connection terminal CW is connected to the output terminal CB3.

[0017] Furthermore, the circuit board 20L is installed in the first brake unit 10L with the detection unit 25 positioned near the rotor 19. In the first brake unit 10L, the rotor 19 and the detection unit 25 constitute a rotation angle sensor that detects the rotation angle of the electric motor 14L. In this embodiment, the rotor 19 constitutes the detected part of the rotation angle sensor.

[0018] When the electric motor 14L rotates, the rotor 19 attached to the rotary shaft 18 rotates. When the rotor 19, formed by a permanent magnet, rotates, the magnetic field around the detection unit 25 changes. When the surrounding magnetic field changes, the electrical resistance of the MR sensor element provided in the detection unit 25 changes. As a result, the detection unit 25 outputs an electrical signal that changes in synchronization with the rotation of the electric motor 14L. The microcontroller 21 detects the rotation angle of the electric motor 14L based on this change in the electrical signal of the detection unit 25.

[0019] 3 shows the configuration of the electric circuit of the first braking unit 10L. As shown in the figure, the drive circuit 22 is provided with switching elements S1 to S6. The microcontroller 21 controls the power supplied to each of the output terminals CB1 to CB3 by turning on and off each of the switching elements S1 to S6. Specifically, the microcontroller 21 controls the power supplied to the output terminal CB1 by turning on and off the switching elements S1 and S2. The microcontroller 21 also controls the power supplied to the output terminal CB2 by turning on and off the switching elements S3 and S4. The microcontroller 21 also controls the power supplied to the output terminal CB3 by turning on and off the switching elements S5 and S6.

[0020] On the other hand, the electric motor 14L has three-phase coils: U-phase, V-phase, and W-phase. The U-phase coil is connected to connection terminal CU via power line L1. The V-phase coil is connected to connection terminal CV via power line L2. The W-phase coil is connected to connection terminal CW via power line L3. Therefore, in the first brake unit 10L, output terminal CB1 of the circuit board 20L is connected to the W-phase coil of the electric motor 14L. Also, in the first brake unit 10L, output terminal CB2 of the circuit board 20L is connected to the U-phase coil of the electric motor 14L. Furthermore, in the first brake unit 10L, output terminal CB3 of the circuit board 20L is connected to the V-phase coil of the electric motor 14L.

[0021] <Connection between the electric motor 14R and the circuit board 20R in the second brake unit 10R> Next, the connection between the electric motor 14R and the circuit board 20R in the second brake unit 10R will be described with reference to Figures 4 and 5. In the vehicle braking system of this embodiment, the electric motor 14R installed in the second brake unit 10R has a common configuration with the electric motor 14L installed in the first brake unit 10L. Also, in the vehicle braking system of this embodiment, the circuit board 20R installed in the second brake unit 10R has a common configuration with the circuit board 20L installed in the first brake unit 10L.

[0022] As shown in Fig. 4, in the second brake unit 10R, the circuit board 20R is connected to the electric motor 14R with its surface F facing the electric motor 14R. In this second brake unit 10R, the connection terminal CW is connected to the output terminal CB1, the connection terminal CU is connected to the output terminal CB2, and the connection terminal CV is connected to the output terminal CB3. That is, as shown in Fig. 5, in the second brake unit 10R, the output terminal CB2 of the circuit board 20R is connected to the U-phase coil of the electric motor 14R, just like in the first brake unit 10L. Meanwhile, in the second brake unit 10R, the output terminal CB1 of the circuit board 20R is connected to the W-phase coil of the electric motor 14R, and the output terminal CB3 of the circuit board 20R is connected to the V-phase coil of the electric motor 14R. That is, the coils of the electric motor 14R connected to the output terminals CB1, CB3 of the circuit boards 20L, 20R are swapped between the first brake unit 10L and the second brake unit 10R. That is, the electric motor 14R of the second brake unit 10R is provided with power lines L1-L3 that are arranged in the same manner as the power lines L1-L3 of the electric motor 14L of the first brake unit 10L. The circuit board 20R of the second brake unit 10R has a plurality of output terminals CB1-CB3 that are arranged in the same manner as the circuit board 20L of the first brake unit 10L. In this embodiment, the electric motor 14L and the circuit board 20L of the first brake unit 10L correspond to the first electric motor and the first circuit board, respectively. The electric motor 14R and the circuit board 20R of the second brake unit 10R correspond to the second electric motor and the second circuit board, respectively.

[0023] The microcontrollers 21 of the circuit boards 20L, 20R store motor control programs for controlling the electric motors 14L, 14R. The microcontroller 21 of the second brake unit 10R stores a motor control program that is common to the microcontroller 21 of the first brake unit 10L. This motor control program is configured on the assumption that the electric motor 14L and the circuit board 20L in the first brake unit 10L are connected and that the detection unit 25 is disposed.

[0024] Similarly, in the second brake unit 10R, the circuit board 20R is connected to the electric motor 14R with the detector 25 located near the rotor 19. As described above, the circuit board 20L of the first brake unit 10L is installed with its back surface B, opposite to the front surface F on which the detector 25 is located, facing the electric motor 14L. In contrast, the circuit board 20R of the second brake unit 10R is installed with its front surface F on which the detector 25 is located facing the electric motor 14L. Therefore, in the second brake unit 10R, the direction of the magnetic field change around the detector 25 caused by the rotation of the electric motor 14R is opposite to that in the first brake unit 10L. The rotor 19 is assembled to the electric motor 14R of the second brake unit 10R with a phase shift of 180 electrical degrees from the assembly phase of the rotor 19 relative to the electric motor 14L of the first brake unit 10L. Therefore, the electrical signal output by the detector 25 of the second braking unit 10R is a signal that represents an electrical angle of "-θ2±180°" relative to the actual electrical angle θ2 of the electric motor 14R.

[0025] <How to assemble the rotor 19> Next, a method for assembling the rotor 19 to the electric motors 14L, 14R will be described. In this embodiment, the electric motors 14L, 14R and the rotor 19 are each provided with a marker for alignment.

[0026] In the case of the first brake unit 10L, when assembling the rotor 19, a positive voltage is applied to the V-phase of the electric motor 14L, a negative voltage is applied to the W-phase, and the voltage of the U-phase is set to "0". This causes the electric motor 14L to rotate to a position where the electrical angle is "0°". In this state, the markers of the electric motor 14L and the rotor 19 are aligned, and then the rotor 19 is assembled to the rotating shaft 18 of the electric motor 14L.

[0027] On the other hand, in the case of the second brake unit 10R, when assembling the rotor 19, a positive voltage is applied to the W-phase of the electric motor 14L, a negative voltage is applied to the V-phase, and the U-phase voltage is set to "0". As a result, the electric motor 14R rotates to a position where the electrical angle is "180°" or "-180°". In this state, the marker of the electric motor 14R and the marker of the rotor 19 are aligned, and then the rotor 19 is assembled to the rotating shaft 18 of the electric motor 14L. As a result, the rotor 19 is assembled to the electric motor 14R of the second brake unit 10R with a phase shift of 180° electrical angle relative to the rotor 19 of the electric motor 14L of the first brake unit 10L.

[0028] <Braking force control> Next, with reference to FIG. 6, the braking force control of the vehicle braking system of this embodiment will be described. When controlling the braking force, the brake ECU 30 first performs a calculation process P1. In the calculation process P1, the brake ECU 30 determines the braking force to be generated in each of the first and second braking units 10L, 10R based on the detection results of the pedal stroke sensor 31, the wheel speed sensor 32, etc. Furthermore, in the calculation process P1, the brake ECU 30 calculates target rotation amounts φ1t, φ2t, which are target values ​​for the rotation amounts φ1, φ2 of the electric motors 14L, 14R of both braking units 10L, 10R, respectively, required to generate the determined braking forces.

[0029] Here, the rotation amounts φ1 and φ2 are defined as follows: A reference linear motion position of the pistons 17L and 17R is set within the linear motion range of the pistons 17L and 17R in the brake units 10L and 10R. The reference linear motion position is, for example, the most retracted position within the linear motion range where the distance between the brake discs 12L and 12R and the pistons 17L and 17R is the longest. Here, the rotation position of the electric motors 14L and 14R when the pistons 17L and 17R are located at the reference linear motion position is defined as a rotation position where the rotation amount is "0." The rotation amount of the electric motors 14L and 14R in the forward direction from the rotation position where the rotation amount is "0" and expressed in mechanical angle of the electric motors 14L and 14R is used as the value of the rotation amounts φ1 and φ2.

[0030] Next, the brake ECU 30 performs a generation process P2 in which it generates command signals for each of the brake units 10L and 10R based on the calculation results of the calculation process P1. In the generation process P2, the brake ECU 30 generates a command signal for the first brake unit 10L that directly indicates the target rotation amount φ1t calculated in the calculation process P1. On the other hand, in the generation process P2, the brake ECU 30 generates a command signal for the second brake unit 10R that indicates a value (−φ2t) obtained by inverting the value of the target rotation amount φ2t calculated in the calculation process P1. The command signal for the second brake unit 10R thus generated instructs the electric motor 14R to rotate in the opposite direction to the direction that should originally be instructed. The brake ECU 30 then outputs the command signals generated in the generation process P2 to the first and second brake units 10L and 10R, respectively. In other words, the brake ECU 30 outputs a command signal to the second braking unit 10R such that when the brake ECU 30 outputs the command signal to the first braking unit 10L, the command for the rotation direction of the electric motor 14L and the command for the rotation direction of the electric motor 14R are opposite to each other.

[0031] In the first and second braking units 10L, 10R, the microcontrollers 21 installed on the circuit boards 20L, 20R receive the command signals output by the brake ECU 30. The microcontrollers 21 control the electric motors 14L, 14R by driving the drive circuits 22 based on the received command signals and the rotation angles of the electric motors 14L, 14R detected by the detectors 25. Specifically, the microcontrollers 21 control the electric motors 14L, 14R so that the current rotation amounts of the electric motors 14L, 14R recognized by the microcontrollers 21 approach the target rotation amounts indicated by the command signals from the brake ECU 30. That is, when the target rotation amounts are greater than the current rotation amounts recognized by the microcontrollers 21, the microcontrollers 21 drive the drive circuits 22 to rotate the electric motors 14L, 14R in the forward direction. On the other hand, when the target rotation amounts are smaller than the current rotation amounts recognized by the microcontrollers 21, the microcontrollers 21 drive the drive circuits 22 to rotate the electric motors 14L, 14R in the reverse direction. Therefore, the command signals generated in the generation process P2 include instructions for the rotation directions of the electric motors 14L and 14R.

[0032] In the second brake unit 10R, the electric motor 14R rotates in the direction opposite to the direction that the microcontroller 21 is attempting to control. The microcontroller 21 of the second brake unit 10R controls the electric motor 14R by recognizing the target rotation amount φ2t of the electric motor 14R and the electrical angle of the electric motor 14R as the following values: The microcontroller 21 of the second brake unit 10R controls the electric motor 14R while recognizing the target rotation amount as the inverted value (-φ2t) of the original target rotation amount φ2t. The microcontroller 21 of the second brake unit 10R controls the electric motor 14R while recognizing the electrical angle of the electric motor 14R as "-θ2±180°" relative to the actual electrical angle θ2.

[0033] <Actions and Effects of the Embodiment> The operation and effects of this embodiment will be described. The arrangement of components of the first brake unit 10L, which is disposed on the left rear wheel 11L, and the second brake unit 10R, which is disposed on the right rear wheel 11R, when assembled to a vehicle is symmetrical. However, the electronic components mounted on the circuit boards 20L, 20R are more susceptible to heat and vibration than the other components of the brake units 10L, 10R. Therefore, the circuit boards 20L, 20R must be installed so that the electronic components are less susceptible to heat and vibration. Therefore, it is preferable to install the circuit boards 20L, 20R on the side of the brake units 10L, 10R, rather than on top of the brake units 10L, 10R, which are more susceptible to heat. In other words, it is preferable to install the circuit boards 20L, 20R perpendicular to the rotation shaft 18 of the electric motors 14L, 14R, rather than parallel to the rotation shaft 18. However, as a result of this arrangement, the electrical connections between the electric motors 14L, 14R and the circuit boards 20L, 20R are different between the first brake unit 10L and the second brake unit 10R. Therefore, when the microcontroller 21 of the second brake unit 10R performs the same motor control as in the first brake unit 10L, the electric motor 14R rotates in the direction opposite to the direction that is being controlled.

[0034] 7 shows the relationship between the electrical angle θ1 of the electric motor 14L of the first brake unit 10L and the terminal currents I1, I2, and I3 of the circuit board 20L. Terminal current I1 indicates the value of the current that the circuit board 20L passes through the electric motor 14L via output terminal CB1. Terminal current I2 indicates the value of the current that the circuit board 20L passes through the electric motor 14L via output terminal CB2. Terminal current I3 indicates the value of the current that the circuit board 20L passes through the electric motor 14L via output terminal CB3. In the case of the first brake unit 10L, terminal current I1 corresponds to the V-phase coil current IV of the electric motor 14L, terminal current I2 corresponds to the U-phase coil current IU of the electric motor 14L, and terminal current I3 corresponds to the W-phase coil current IW of the electric motor 14L.

[0035] 8 shows the relationship between the electrical angle θ2 of the electric motor 14R of the second brake unit 10R and the terminal currents I1, I2, and I3 of the circuit board 20R. In the case of the second brake unit 10R, the terminal current I1 corresponds to the W-phase coil current IW of the electric motor 14R, the terminal current I2 corresponds to the U-phase coil current IU of the electric motor 14R, and the terminal current I3 corresponds to the V-phase coil current IV of the electric motor 14R. That is, in the second brake unit 10R, the V-phase coil current IV and the W-phase coil current IW are interchanged compared to the first brake unit 10L.

[0036] On the other hand, the graph in Figure 9 is a graph in which the waveforms of the terminal currents I1 to I3 in Figure 7 are plotted on a graph with the horizontal axis set to "-θ2±180°." The waveforms of the terminal currents I1 to I3 in Figures 7 and 9 are the same. Therefore, if the microcontroller 21 of the second braking unit 10R is made to recognize the following (A) and (B), appropriate motor control can also be performed in the second braking unit 10R. (A) The microcontroller 21 of the second braking unit 10R is made to recognize the angle that is "θ2±180°" with respect to the actual electrical angle θ2 as the electrical angle of the electric motor 14R. (B) The microcontroller 21 of the second braking unit 10R is made to recognize the value obtained by inverting the actual target value as the target value for the amount of rotation of the electric motor 14R.

[0037] In the vehicle braking system of this embodiment, rotors 19 of rotation angle sensors are attached to the rotating shafts 18 of the electric motors 14L, 14R of both brake units 10L, 10R. The rotor 19 of the second brake unit 10R is attached with a phase shift of 180° in electrical angle of the electric motors 14L, 14R relative to the rotor 19 of the first brake unit 10L. In this way, the recognition of (A) above is achieved in this embodiment.

[0038] Furthermore, the brake ECU 30 in the vehicle braking system of this embodiment calculates target rotation amounts φ1t and φ2t of the electric motors 14L and 14R of the first and second braking units 10L and 10R in a calculation process P1. When generating a command signal for the first braking unit 10L in a generation process P2, the brake ECU 30 generates the command signal using the calculated value of the calculation process P1 as is. On the other hand, when generating a command signal for the second braking unit 10R in a generation process P2, the brake ECU 30 generates the command signal using a value obtained by inverting the calculated value of the calculation process P1. In this embodiment, the recognition (B) above is thereby achieved.

[0039] In this embodiment, the microcontroller 21 of the second brake unit 10R is made to recognize the above (A) and (B). Therefore, even in the second brake unit 10R, in which the combination of coils of the electric motor 14R connected to the output terminals CB1 to CB3 of the circuit board 20R is different from that of the first brake unit 10L, proper motor control can be performed.

[0040] Note that the command signal from the brake ECU 30 to the second brake unit 10R to rotate the electric motor 14R in the forward direction becomes a signal that causes the electric motor 14L to rotate in the reverse direction when the same command signal is output to the first brake unit 10L. Also, the command signal from the brake ECU 30 to the second brake unit 10R to rotate the electric motor 14R in the reverse direction becomes a signal that causes the electric motor 14L to rotate in the forward direction when the same command signal is output to the first brake unit 10L.

[0041] <Other embodiments> This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility.

[0042] In the above embodiment, the output terminal CB2 of the circuit boards 20L, 20R connected to the U-phase coil is common to the first and second brake units 10L, 10R. The output terminals CB1, CB2 of the circuit boards 20L, 20R connected to the V-phase and W-phase coils are switched between the first and second brake units 10L, 10R. The coil combinations for which the output terminals CB1, CB2 of the circuit boards 20L, 20R connected to the first and second brake units 10L, 10R are switched may be different from those in the above embodiment. For example, the output terminals CB1, CB3 connected to the U-phase coil and the output terminals CB3, CB1 connected to the V-phase coil may be switched between the first and second brake units 10L, 10R. In this case, it is desirable to assemble the rotor 19 of the electric motor 14R of the second brake unit 10R with a phase shift of "-60°" electrical angle relative to the rotor 19 of the first brake unit 10L. Furthermore, the output terminals CB1 and CB3 connected to the U-phase coil and the output terminals CB3 and CB1 connected to the W-phase coil may be swapped between the first and second brake units 10L and 10R. In this case, it is desirable to assemble the rotor 19 of the electric motor 14R of the second brake unit 10R with a phase shift of "60°" electrical angle relative to the rotor 19 of the electric motor 14L of the first brake unit 10L. The electrical angle of the electric motor 14R can be maintained at "-60°" by applying a positive voltage to the U-phase coil, a negative voltage to the V-phase coil, and setting the voltage applied to the W-phase coil to "0". Furthermore, if a negative voltage is applied to the U-phase coil, a positive voltage is applied to the W-phase coil, and the voltage applied to the V-phase coil is set to "0", the electrical angle of the electric motor 14R can be maintained at "60°". Therefore, in these cases as well, the assembly work of the rotor 19 can be performed in the same manner as in the above embodiment.

[0043] In the first brake unit 10L of the above embodiment, the rotor 19 and the detector 25 of the rotation angle sensor are disposed with the circuit board 20L interposed therebetween. On the other hand, in the second brake unit 10R, the circuit board 20R is not interposed between the rotor 19 and the detector 25 of the rotation angle sensor. Therefore, the detector 25 of the first brake unit 10L has a lower signal output level than the detector 25 of the second brake unit 10R. Therefore, if the circuit boards 20L and 20R of both brake units 10L and 10R have a common configuration, one of the brake units 10L and 10R may not be able to properly detect the rotation angle of the electric motors 14L and 14R. In such a case, the following measures can be taken to ensure the accuracy of detecting the rotation angle of the electric motors 14L and 14R in both brake units 10L and 10R. The first measure is to use a thicker permanent magnet for the rotor 19 assembled to the electric motor 14L of the first brake unit 10L than for the rotor 19 assembled to the electric motor 14R of the second brake unit 10R. The second measure is to assemble the rotor 19 of the first brake unit 10L at a position closer to the circuit boards 20L, 20R than that of the second brake unit 10R. The third measure is to provide holes in the circuit boards 20L, 20R at the mounting positions of the detectors 25. The fourth measure is to provide a function to automatically adjust the output level of the detectors 25.

[0044] In the above embodiment, an MR sensor utilizing the magnetic field resistance effect was used as the rotation angle sensor. However, a sensor other than an MR sensor, such as an eddy current rotation angle sensor including a rotor 19 formed of a magnetic material and a detection unit 25 having an excitation coil and an output coil, may also be used. In the above embodiment, the detection unit 25 of the second brake unit 10R is disposed with the opposite side of the detection unit 25 of the first brake unit 10L facing the rotor 19. This allows the microcontroller 21 of the second brake unit 10R to recognize the rotation direction of the electric motor 14R as opposite to the actual direction, thereby achieving appropriate motor control. When a rotation angle sensor other than an MR sensor is used, even if the detection units 25 of the two brake units 10L and 10R are disposed with different sides facing the rotor 19, the microcontroller 21 may recognize the same rotation direction of the electric motor 14L. For example, an eddy current sensor is available in which the detection unit 25 is configured with a sheet-shaped excitation coil and output coil. Because the coil of the detector 25 of such a sensor has a two-dimensional structure, the output pattern of the detector 25 does not change even if the detector 25 is installed upside down with respect to the rotor 19. When using such a sensor, the following measure can be taken to make the microcontroller 21 of the second brake unit 10R recognize the rotation direction of the electric motor 14R as being opposite to the actual direction. That is, the first brake unit 10L is provided with a rotor 19 made of a paramagnetic or ferromagnetic material, while the second brake unit 10R is provided with a rotor 19 made of a diamagnetic material. In this case, the signal output patterns of the detector 25 in response to the rotation of the rotor 19 are opposite between the first brake unit 10L and the second brake unit 10R. This makes it possible to make the microcontroller 21 of the second brake unit 10R recognize the rotation direction of the electric motor 14R as being opposite to the actual direction.

[0045] In the first brake unit 10L, the circuit board 20L may be installed with its front surface F facing the electric motor 14L. In this case, in the second brake unit 10R, the circuit board 20R should be installed with its back surface B facing the electric motor 14R.

[0046] Even if the positional relationship between the circuit boards 20L, 20R and the electric motors 14L, 14R differs from that of the above embodiment, the coils of the electric motors 14L, 14R connected to the output terminals CB1, CB3 of the first and second brake units 10L, 10R may be swapped. For example, even if the sides of the circuit boards 20L, 20R facing the electric motors 14L, 14R are the same in both the first brake unit 10L and the second brake unit 10R, the above-mentioned coil swapping may occur in the following case. That is, the positional relationship between the input terminals 23 and the electric motors 14L, 14R differs between the first brake unit 10L and the second brake unit 10R. Even in such a case, proper motor control of both brake units 10L, 10R can be achieved by performing braking force control similar to that of the above embodiment.

[0047] The braking units 10L and 10R do not necessarily have to have a rotation angle sensor. The electric motors 14L, 14R provided in the braking units 10L, 10R do not have to be three-phase AC synchronous motors as long as they rotate in both forward and reverse directions. For example, the electric motors 14L, 14R may be synchronous motors with four or more phases. Furthermore, for example, the electric motors 14L, 14R may be DC motors with brushes.

[0048] The circuit boards 20L and 20R may be substantially identical. "Substantially identical" here means that they have the same specifications for the microcontroller 21, drive circuit 22, input terminal 23, and three output terminals CB1, CB2, and CB3. As long as these components are included, one of the circuit boards 20L and 20R may be equipped with electronic components, such as resistor elements, that are not installed on the other board.

[0049] In the above embodiment, the brake ECU 30 constitutes a command unit of the vehicle braking system. Such a command unit of the vehicle braking system may be configured as a circuit including one or more processors operating according to a computer program, one or more dedicated hardware circuits such as dedicated hardware that executes at least some of the various processes, or a combination thereof. Examples of dedicated hardware include an application-specific integrated circuit (ASIC). The processor includes a CPU and memory such as RAM and ROM, and the memory stores program code or instructions configured to cause the CPU to execute processes. The memory, i.e., storage medium, includes any available medium accessible by a general-purpose or dedicated computer.

[0050] The technical ideas that can be understood from the above-described embodiment and modified examples will be described. (A) A vehicle braking device having first and second braking units that generate a braking force for a vehicle by pressing a friction material against a rotating body that rotates integrally with a wheel of the vehicle, and a command unit, wherein the first braking unit has a first electric motor that can rotate in a forward and reverse direction to displace the friction material in a direction toward the rotating body or in a direction away from the rotating body, and a first circuit board that has a plurality of terminals that are respectively connected to power lines of the first electric motor and is provided with an electric circuit for controlling the power supplied to each terminal based on a command signal input from the command unit, and the second braking unit can rotate in a forward and reverse direction to displace the friction material in a direction toward the rotating body or in a direction away from the rotating body, and a second electric motor provided with power lines that are arranged in the same manner as the power lines of a first electric motor; and a second circuit board having a plurality of terminals that are respectively connected to the power lines of the second electric motor and that have the same terminal arrangement as the plurality of terminals of the first circuit board, and having an electric circuit provided thereon for controlling the power supplied to each of the terminals based on a command signal input from the command unit, wherein the command unit outputs the command signal to the first and second brake units, the command signal including an instruction for the rotational direction of the first and second electric motors, and when the command signal is output to the second brake unit, the command signal to the first brake unit is output in the opposite direction to the rotational direction to the second electric motor. [Explanation of symbols]

[0051] 10L...First braking unit 10R...Second braking unit 11L…Left rear wheel (wheel) 11R...Right rear wheel (wheel) 12L, 12R...Brake disc (rotating body) 13L, 13R...Brake pads (friction material) 14L, 14R...Electric motor 15L,15R…Reduction mechanism 16L, 16R... Linear motion conversion mechanism 17L, 17R... Piston 18...Rotation axis 19...Rotor (detected part) 20L, 20R...Circuit board 21...Microcontroller 22...Drive circuit 23...Input terminal 25...Detection unit 30...Brake ECU (control unit) 31...Pedal stroke sensor 32...Wheel speed sensor 33...Battery CB1, CB2, CB3...Output terminals CU, CV, CW...connection terminals L1,L2,L3…power line S1 to S6: Switching elements

Claims

1. A vehicle braking device comprising: first and second braking units that generate a braking force for a vehicle by pressing a friction material against a rotating body that rotates integrally with a wheel of the vehicle; and a command unit, The first and second braking units each include an electric motor that is rotatable in a forward direction and a reverse direction so as to displace the friction material in a direction toward the rotating body or in a direction away from the rotating body, and a circuit board that has a plurality of terminals that are connected to respective power lines of the electric motor and is provided with an electric circuit for controlling the power supplied to each of the terminals based on a command signal input from the command unit, The command unit outputs the command signal including an instruction for the rotation direction of the electric motor to the first and second brake units, and when outputting the command signal to the second brake unit to the first brake unit, the command for the rotation direction of the electric motor from the first brake unit and the command for the rotation direction of the electric motor from the second brake unit are opposite to each other. Vehicle braking system.

2. The command unit a calculation process for calculating at least one of a rotation amount and a rotation speed of the electric motor according to the braking force to be generated; a generation process in which, when generating the command signal for the first brake unit, a calculated value of the arithmetic process is used as is to generate the command signal, and, when generating the command signal for the second brake unit, a value obtained by inverting the calculated value of the arithmetic process to generate the command signal; 2. The vehicle braking system according to claim 1, wherein the brake pedal is operated in a manner such that ...

3. the first and second braking units each include a rotation angle sensor having a detected portion rotatable together with a rotation shaft of the electric motor, and a detecting portion installed on the circuit board and configured to detect a signal output from the detected portion; The first brake unit and the second brake unit have different assembly phases of the detection target portion relative to the rotary shaft.

3. A vehicle braking system according to claim 1 or 2.

4. 4. The vehicle braking device according to claim 3, wherein in the first brake unit, the circuit board is installed with the installation surface of the detection unit facing the electric motor, and in the second brake unit, the circuit board is installed with the surface opposite to the installation surface of the detection unit facing the electric motor.

5. The detected portion of either the first or second braking unit is made of a paramagnetic or ferromagnetic material, and the detected portion of the other braking unit is made of a diamagnetic material.

5. A vehicle braking system according to claim 4.

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