Brake device

Abstract

To provide a brake-by-wire type brake device that can eliminate the need for intervention of a hydraulic mechanism.SOLUTION: A pedal 11 displaces centering on a first pivot axis A1 by a depression operation to brake a movable body. A first movable member 121 is displaceable together with the pedal 11. A second movable member 122 is displaceable independently of the pedal 11. A torsion bar 13 connects the first movable member 121 and the second movable member 122 and allows relative displacement between the first movable member 121 and the second movable member 122 through elastic deformation. A first sensor 141 outputs a first signal S1 corresponding to the displacement amount of the first movable member 121. A second sensor 142 outputs a second signal S2 corresponding to the displacement amount of the second movable member 122. A drive mechanism 15 supplies a driving force to the second movable member 122 to adjust the difference between the displacement amount of the first movable member 121 and the displacement amount of the second movable member 122 on the basis of the first signal S1 and the second signal S2.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a brake-by-wire type brake device.

Background Art

[0002] Patent Document 1 discloses a brake-by-wire type brake device that controls braking force by converting the operation amount of a pedal into an electric signal. The device creates the operation feeling of the pedal using a stroke simulator with a hydraulic mechanism interposed therebetween.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] There is a demand for providing a brake-by-wire type brake device that can eliminate the need for a hydraulic mechanism.

Means for Solving the Problems

[0005] One aspect example provided by the present disclosure is a brake device including: a pedal that is displaced about a first pivot axis by a stepping operation and brakes a moving body; a first movable member displaceable together with the pedal; a second movable member displaceable independently of the pedal; an elastic member that connects the first movable member and the second movable member and allows relative displacement between the first movable member and the second movable member by elastic deformation; a first sensor that outputs a first signal corresponding to the displacement amount of the first movable member; a second sensor that outputs a second signal corresponding to the displacement amount of the second movable member; Based on the first signal and the second signal, a drive mechanism that supplies a driving force for adjusting the difference in the displacement amounts of the first movable member and the second movable member to the second movable member, is provided.

[0006] According to the above configuration, with the depression operation of the pedal, a difference in displacement amount occurs between the first movable member and the second movable member through the deformation of the elastic member. By the drive mechanism supplying a driving force to the second movable member so as to adjust the difference in displacement amount, the pedal feel can be created without interposing a hydraulic mechanism. Since it is possible to dispense with the interposition of the hydraulic mechanism, it is possible to provide a brake-by-wire type brake device that can suppress an increase in size and complexity of the structure.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Mode for Carrying Out the Invention

[0008] With reference to the accompanying drawings, examples of embodiments will be described in detail below. In each of the drawings used in the following description, the scale is appropriately changed in order to make each element recognizable in size.

[0009] FIG. 1 illustrates the functional configuration of a brake device 10 according to a first exemplary embodiment. The brake device 10 is configured to be mounted on a moving body such as a vehicle.

[0010] The brake device 10 includes a pedal 11. The pedal 11 is configured to receive a stepping operation by the foot of an occupant of the vehicle in order to perform braking of the vehicle. As shown by the dashed two-dot line in FIG. 2, the pedal 11 is displaceable forward of the vehicle about a first pivot axis A1 by a stepping operation.

[0011] The brake device 10 includes a biasing mechanism (not shown) that biases the pedal 11 toward the initial position shown by the solid line in FIG. 2. When the occupant releases the stepping force, the pedal 11 is displaced rearward of the vehicle about the first pivot axis A1 by the biasing force of the biasing mechanism and automatically returns to the initial position.

[0012] As illustrated in FIGS. 1 and 2, the brake device 10 includes a first movable member 121. One end of the pedal 11 is connected to the first movable member 121. The first movable member 121 is configured to be rotatable about a second pivot axis A2 along with the operation of the pedal 11. In the present exemplary embodiment, the first pivot axis A1 and the second pivot axis A2 coincide.

[0013] Note that if the first pivot axis A1 and the second pivot axis A2 extend in parallel, it is not necessarily required that the two axes coincide.

[0014] The braking device 10 includes a second movable member 122 and a torsion bar 13. The torsion bar 13 coaxially connects the first movable member 121 and the second movable member 122. The torsion bar 13 is configured to allow relative displacement between the first movable member 121 and the second movable member 122 by torsional deformation. As a result, the second movable member 122 is rotatable independently of the pedal 11 about the second rotation axis A2. The torsion bar 13 is an example of an elastic member.

[0015] If the relative displacement between the first movable member 121 and the second movable member 122 can be allowed to be restored by torsional elastic deformation, the torsion bar 13 can be replaced by a torsion spring, a rubber shaft, or the like.

[0016] The braking device 10 includes a first sensor 141. The first sensor 141 is configured to detect the amount of rotation of the first movable member 121 and output a first signal S1 corresponding to the amount of rotation. The detection of the amount of rotation of the first movable member 121 by the first sensor 141 can be performed using an appropriate well-known method such as optical, magnetic, or mechanical.

[0017] The braking device 10 includes a second sensor 142. The second sensor 142 is configured to detect the amount of rotation of the second movable member 122 and output a second signal S2 corresponding to the amount of rotation. The detection of the amount of rotation of the second movable member 122 by the second sensor 142 can be performed using an appropriate well-known method such as optical, magnetic, or mechanical.

[0018] The braking device 10 includes a drive mechanism 15. The drive mechanism 15 includes a first gear 151, a second gear 152, and a motor 153. The first gear 151 is coupled to the second movable member 122. The second gear 152 is coupled to the motor 153. The first gear 151 and the second gear 152 are meshed. Therefore, when the motor 153 is driven, the second gear 152 rotates, and the driving force is transmitted to the second movable member 122 via the first gear 151. Thereby, the second movable member 122 is rotated about the second rotation axis A2.

[0019] Note that the second gear 152 when the motor 153 is not driven is rotatable following the rotation of the first gear 151.

[0020] The brake device 10 includes a control device 16. The control device 16 includes an input interface that receives a first signal S1 output from the first sensor 141 and a second signal S2 output from the second sensor 142. The first signal S1 and the second signal S2 may be analog signals or digital signals according to the specifications of the first sensor 141 and the second sensor 142.

[0021] The input interface is configured as a hardware interface. When the first signal S1 and the second signal S2 are analog signals, the input interface includes an appropriate conversion circuit including an A / D converter. This description is similarly applicable to other signals to be received by the input interface described later.

[0022] The control device 16 includes a processor and an output interface. The processor is configured to output a braking signal BS for operating a brake system mounted on the vehicle from the output interface based on the displacement amount of the pedal 11 specified at least based on the first signal S1. That is, the brake device 10 is a brake-by-wire type brake device.

[0023] The output interface is configured as a hardware interface. The braking signal BS may be an analog signal or a digital signal according to the specifications of the brake system. When the braking signal BS is an analog signal, the output interface includes an appropriate conversion circuit including a D / A converter. This description is similarly applicable to other signals that can be output by the output interface described later.

[0024] The processor is configured to output a control signal CS for controlling the operation of the motor 153 from an output interface based on the first signal S1 and the second signal S2. The control signal CS may be an analog signal or a digital signal according to the specifications of the motor 153.

[0025] With reference to FIGS. 3 and 4, the details of the operation control of the motor 153 by the control device 16 will be described.

[0026] When a depressing operation is performed on the pedal 11 by an occupant, the first movable member 121 rotates counterclockwise about the second rotation axis A2 as viewed from the right side of the pedal 11 (see FIG. 2). For example, when a first signal S1 indicating the rotation of the first movable member 121 exceeding a predetermined value is received at the input interface of the control device 16, the processor causes the drive mechanism 15 to supply a driving force that prevents the second movable member 122 from rotating following the first movable member 121.

[0027] Specifically, the processor causes the drive mechanism 15 to transmit a driving force that acts in the clockwise direction with respect to the second movable member 122 as viewed from the right side of the pedal 11. That is, the processor outputs a control signal CS from the output interface to drive the motor 153 so that a driving force acts in the counterclockwise direction with respect to the second gear 152 as viewed from the same direction in order to apply a counterforce in the clockwise direction to the first gear 151 as viewed from the right side of the pedal 11.

[0028] As a result, as illustrated in FIG. 3, the first movable member 121 rotates counterclockwise as viewed from the right side of the pedal 11 while twisting and deforming the torsion bar 13. The resistance force against the elastic deformation of the torsion bar 13 acts on the pedal 11 through the first movable member 121. The resistance force is recognized by the occupant as a reaction force against the depressing operation. On the other hand, a difference occurs between the amount of rotation of the first movable member 121 indicated by the first signal S1 and the amount of rotation of the second movable member 122 indicated by the second signal S2.

[0029] Subsequently, the processor of the control device 16 causes the drive mechanism 15 to supply a driving force for rotating the second movable member 122 so as to eliminate the difference in the amount of rotation between the first movable member 121 and the second movable member 122. In other words, the driving force is supplied to the second movable member 122 so as to eliminate the torsional deformation of the torsion bar 13.

[0030] Specifically, the processor causes the drive mechanism 15 to transmit a driving force for rotating the second movable member 122 counterclockwise as viewed from the right side of the pedal 11. That is, the processor outputs a control signal CS from the output interface for driving the motor 153 so that the second gear 152 rotates clockwise as viewed from the same direction in order to rotate the first gear 151 counterclockwise as viewed from the right side of the pedal 11.

[0031] In order to eliminate the torsional deformation of the torsion bar 13, the rotation speed of the second movable member 122 needs to be higher than the rotation speed of the first movable member 121. The control signal CS is determined so that the rotation speed of the second gear 152 can satisfy this requirement.

[0032] As a result, as illustrated in FIG. 4, both the first movable member 121 and the second movable member 122 rotate counterclockwise as viewed from the right side of the pedal 11 while eliminating the torsional deformation of the torsion bar 13. The processor of the control device 16 continues to monitor the first signal S1 and the second signal S2, and continues to drive the motor 153 until the difference in the amount of rotation between the first movable member 121 and the second movable member 122 is eliminated. When it is determined that the difference in the amount of rotation has been eliminated, the processor stops driving the motor 153.

[0033] When the driving of the motor 153 is stopped from the state in which the rotation of the second movable member 122 illustrated in FIG. 3 is blocked, the second movable member 122 immediately undergoes a displacement that eliminates the difference in the amount of rotation with the first movable member 121 due to the elastic restoring force of the torsion bar 13. In this case, the occupant feels that the reaction force felt at the beginning of the depression operation of the pedal 11 is lost.

[0034] Therefore, by setting the rotation speed of the second movable member 122 to be lower than the rotation speed of the torsion bar 13 accompanying the elastic return of the torsion bar 13 without being lower than the rotation speed of the first movable member 121, the reaction force against the depressing operation of the pedal 11 can be felt by the occupant. In other words, the feel of the pedal 11 can be adjusted according to the timing of releasing the rotation stop of the second movable member 122 and the subsequent rotation speed of the second movable member 122.

[0035] As an example, by relatively quickly releasing the rotation stop of the second movable member 122 and setting the rotation speed of the second movable member 122 to be relatively fast, the time until the difference in the rotation amounts between the first movable member 121 and the second movable member 122 is eliminated becomes shorter, and a relatively light feel of the pedal 11 can be created. As another example, by relatively slowly releasing the rotation stop of the second movable member 122 and setting the rotation speed of the second movable member 122 to be relatively slow, the time until the difference in the rotation amounts between the first movable member 121 and the second movable member 122 is eliminated becomes longer, and a relatively heavy feel of the pedal 11 can be created.

[0036] That is, in the brake device 10 according to the present embodiment, with the depressing operation of the pedal 11, a difference in the rotation amount occurs between the first movable member 121 and the second movable member 122 through the torsional deformation of the torsion bar 13. By the drive mechanism 15 supplying a driving force to the second movable member 122 so as to adjust the difference in the rotation amount, the feel of the pedal 11 can be created without interposing a hydraulic mechanism. Since the interposition of the hydraulic mechanism can be made unnecessary, a brake-by-wire type brake device 10 that can suppress an increase in size and complexity of the structure can be provided.

[0037] The rotation speed of the second movable member 122 may be constant or may vary. Particularly in the latter case, a more delicate feel of the pedal 11 can be created with a high degree of freedom without interposing a hydraulic mechanism.

[0038] The feel of the pedal 11 is also related to the stepping force of the occupant. The feel created by setting the timing for releasing the rotation prevention of the second movable member 122 and the rotation speed of the second movable member 122 to specific values may feel heavy to an occupant with a weak stepping force, while it may feel light to an occupant with a strong stepping force. Therefore, the timing for releasing the rotation prevention of the second movable member 122 and the rotation speed of the second movable member 122 can be changed according to the stepping force of the occupant.

[0039] The stepping force of the occupant may correspond to the amount of rotation per unit time of the first movable member 121 at the initial stage of the stepping operation of the pedal 11. Therefore, the processor of the control device 16 can detect the stepping force of the occupant by specifying the amount of rotation per unit time of the first movable member 121 based on the first signal S1.

[0040] As an example, the rotation of the second movable member 122 can be controlled so as to provide a constant feel regardless of the stepping force of the occupant. Specifically, when a relatively weak stepping force is detected, the rotation of the second movable member 122 can be controlled so as to create a relatively light feel, and when a relatively strong stepping force is detected, a relatively heavy feel is created.

[0041] As another example, the control device 16 can receive an instruction from the occupant to select a preferred feel from a plurality of levels through a user interface (not shown) mounted on the vehicle. The control device 16 makes settings related to the rotation of the second movable member 122 so that a feel according to the preference of the occupant is created according to the instruction.

[0042] According to such a configuration, creation of the feel of the pedal 11 according to the stepping force of the occupant can be realized without interposing a hydraulic mechanism.

[0043] The brake device 10 can have a failure detection function for each of the first sensor 141 and the second sensor 142.

[0044] As an example, as shown in FIG. 5, communication for fault detection can be made between the control device 16 and each of the first sensor 141 and the second sensor 142. Specifically, the control device 16 periodically transmits an interrogation signal for diagnosis to each of the first sensor 141 and the second sensor 142. Each of the first sensor 141 and the second sensor 142 is configured to transmit a response signal to the interrogation signal. When a response signal to the interrogation signal cannot be obtained from either the first sensor 141 or the second sensor 142, the control device 16 determines that the sensor is faulty.

[0045] As another example, each of the first sensor 141 and the second sensor 142 may have a self-diagnosis function. When a signal indicating a fault is received from either the first sensor 141 or the second sensor 142, the control device 16 determines that the sensor is faulty.

[0046] Specifically, each of the first sensor 141 and the second sensor 142 is duplicated by two sensor elements with different outputs for the rotation angle of the detected movable member. For example, a sensor element that provides an output having a positive correlation with the detected rotation angle and a sensor element that provides an output having a negative correlation with the detected rotation angle are used. Each output is determined such that the sum of both outputs is constant regardless of the detected rotation angle, and the value of the sum is used for monitoring. When a fault occurs in either one of the sensor elements, the value of the sum deviates from a constant value, enabling self-diagnosis of the fault.

[0047] When a fault is detected in either the first sensor 141 or the second sensor 142, the control device 16 can be configured to stop supplying a driving force to the second movable member 122 to the drive mechanism 15. FIG. 6 illustrates the case where a fault is detected in the first sensor 141. Specifically, the control device 16 stops outputting a control signal CS for driving the motor 153. As a result, the first gear 151 and the second gear 152 reach a no-load state.

[0048] When a stepping operation is performed on the pedal 11 in this state, the second movable member 122 also rotates by the same amount following the rotation of the first movable member 121. Therefore, the second signal S2 reflects the operation amount of the pedal 11. The control device 16 outputs a braking signal BS that causes the braking system to brake the moving body according to the operation amount of the pedal 11 based on the second signal S2. When a failure occurs in the second sensor 142, the braking signal BS may be output based on the first signal S1.

[0049] According to such a configuration, although the function of creating the feel of stepping on the pedal 11 by the drive mechanism 15 is invalidated, even if a failure occurs in either the first sensor 141 or the second sensor 142, the essential braking function as the brake-by-wire type brake device 10 can be ensured.

[0050] In order to enhance the robustness of the brake device 10 against failures, it is preferable that the first sensor 141 and the second sensor 142 are each supplied with power from a separate power source system.

[0051] There may be a failure in which the motor 153 stops in a locked state while applying a load to the second gear 152. The brake device 10 may be provided with a detection function for such a failure state. For example, as shown in FIG. 5, the control device 16 outputs a control signal CS that causes the motor 153 to perform a drive to slightly rotate the second gear 152. When the rotation of the second movable member 122 based on the second signal S2 is not detected with respect to this control signal CS, it is determined that the motor 153 has stopped in a locked state.

[0052] In this case, the control device 16 is configured to output a braking signal BS that causes the braking system to brake the moving body within the range of the rotation amount difference between the first movable member 121 and the second movable member 122 caused by the torsional deformation of the torsion bar 13 accompanying the stepping operation of the pedal 11.

[0053] According to such a configuration, although the function of creating the feel of stepping on the pedal 11 by the drive mechanism 15 is invalidated, even if a failure occurs in which the motor 153 stops in a locked state, the braking function essential for the brake-by-wire type brake device 10 can be ensured.

[0054] In addition, in order to enhance the robustness of the brake device 10 against failures, it is preferable that the motor 153 is supplied with power from power sources of different systems from each of the first sensor 141 and the second sensor 142.

[0055] In the present embodiment, the drive mechanism 15 supplies a driving force to the second movable member 122 so as to perform an adjustment that reduces the difference in the amount of rotation between the first movable member 121 and the second movable member 122 that occurs along with the torsional deformation of the torsion bar 13. However, the drive mechanism 15 may temporarily perform an adjustment that increases the difference in the amount of rotation between the first movable member 121 and the second movable member 122 according to the feel of stepping on the created pedal 11.

[0056] FIG. 7 illustrates the functional configuration of the brake device 20 according to the second embodiment. The brake device 20 is configured to be mounted on a moving body such as a vehicle.

[0057] The brake device 20 includes a pedal 21. The pedal 21 is configured to receive a stepping operation by the foot of an occupant of the vehicle in order to perform braking of the vehicle. As illustrated in FIG. 8, the pedal 21 is displaceable forward of the vehicle about the first rotation axis A1 by a stepping operation.

[0058] The brake device 20 includes a biasing mechanism (not shown) that biases the pedal 21 toward the initial position indicated by the two-dot chain line in FIG. 8. When the occupant releases the stepping force, the pedal 21 is displaced rearward of the vehicle about the first rotation axis A1 by the biasing force of the biasing mechanism and automatically returns to the initial position.

[0059] As illustrated in FIG. 7, the brake device 20 includes a first movable member 221. The pedal 21 is connected to the first movable member 221. The first movable member 221 is configured to be displaceable in the longitudinal direction of the vehicle together with the pedal 21. The longitudinal direction of the vehicle is an example of a direction intersecting the first rotation axis A1.

[0060] The brake device 20 includes a second movable member 222 and a coil spring 23. The second movable member 222 is disposed in front of the first movable member 221. The coil spring 23 connects the first movable member 221 and the second movable member 222. The coil spring 23 is configured to allow relative displacement between the first movable member 221 and the second movable member 222 by expansion and contraction. As a result, the second movable member 222 is displaceable independently of the pedal 21. The coil spring 23 is an example of an elastic member.

[0061] If it is possible to allow relative displacement between the first movable member 221 and the second movable member 222 to be restored by expansion and contraction deformation, the coil spring 23 can be replaced by a leaf spring, a rubber pad, or the like.

[0062] The brake device 20 includes a first sensor 241 and a first pinion gear 251. The first pinion gear 251 meshes with a first rack gear 221a provided on the first movable member 221. Therefore, as the first movable member 221 is displaced, the first pinion gear 251 rotates. The first sensor 241 is configured to detect the displacement amount of the first movable member 221 through the rotation amount of the first pinion gear 251 and output a first signal S1 corresponding to the displacement amount. Detection of the rotation amount of the first pinion gear 251 by the first sensor 241 can be performed using an appropriate well-known method such as optical, magnetic, or mechanical.

[0063] The braking device 20 includes a second sensor 242 and a second pinion gear 252. The second pinion gear 252 meshes with a second rack gear 222a provided on a second movable member 222. Therefore, as the second movable member 222 is displaced, the second pinion gear 252 rotates. The second sensor 242 is configured to detect the displacement amount of the second movable member 222 through the rotation amount of the second pinion gear 252 and output a second signal S2 corresponding to the displacement amount. Detection of the rotation amount of the second pinion gear 252 by the second sensor 242 can be performed using an appropriate well-known method such as optical, magnetic, or mechanical.

[0064] When the first pinion gear 251 and the second pinion gear 252 are in a no-load state, as the pedal 21 is depressed, the first movable member 221 and the second movable member 222 are displaced by the same amount without deforming the coil spring 23. In other words, the elastic restoring force of the coil spring 23 is determined to such an extent that such an operation can be realized.

[0065] The braking device 20 includes a drive mechanism 25. The drive mechanism 25 includes the second pinion gear 252 and a motor 253. The second pinion gear 252 is coupled to the motor 253. When the motor 253 is driven, the second pinion gear 252 rotates and a driving force is transmitted to the second movable member 222. As a result, the second movable member 222 is displaced in the longitudinal direction of the vehicle.

[0066] The braking device 20 includes a control device 26. The control device 26 includes an input interface that receives a first signal S1 output from the first sensor 241 and a second signal S2 output from the second sensor 242. The first signal S1 and the second signal S2 may be analog signals or digital signals depending on the specifications of the first sensor 241 and the second sensor 242.

[0067] The input interface is configured as a hardware interface. When the first signal S1 and the second signal S2 are analog signals, the input interface includes an appropriate conversion circuit including an A / D converter. This description is similarly applicable to other signals to be received by the input interface described later.

[0068] The control device 26 includes a processor and an output interface. The processor is configured to output a braking signal BS for operating a braking system mounted on the vehicle from the output interface based on the displacement amount of the pedal 11 specified based on at least the first signal S1. That is, the braking device 20 is a brake-by-wire type braking device.

[0069] The output interface is configured as a hardware interface. The braking signal BS may be an analog signal or a digital signal according to the specifications of the braking system. When the braking signal BS is an analog signal, the output interface includes an appropriate conversion circuit including a D / A converter. This description is similarly applicable to other signals that can be output by the output interface described later.

[0070] The processor is configured to output a control signal CS for controlling the operation of the motor 253 from the output interface based on the first signal S1 and the second signal S2. The control signal CS may be an analog signal or a digital signal according to the specifications of the motor 253.

[0071] With reference to FIGS. 8 and 9, the details of the operation control of the motor 253 by the control device 26 will be described.

[0072] When a depression operation is performed on the pedal 21 by an occupant, the first movable member 221 is displaced forward. For example, when a first signal S1 indicating a displacement of the first movable member 121 exceeding a predetermined value is received by the input interface of the control device 26, the processor causes the drive mechanism 25 to supply a driving force that prevents the second movable member 222 from displacing following the first movable member 221.

[0073] Specifically, the processor causes the drive mechanism 25 to transmit a driving force acting rearward on the second movable member 222. That is, the processor outputs a control signal CS from the output interface to drive the motor 253 so that a driving force acts on the second pinion gear 252 in the counterclockwise direction when viewed from the right side of the pedal 21.

[0074] As a result, as illustrated in FIG. 8, the first movable member 221 is displaced rearward while compressing and deforming the coil spring 23. A resistance force against the compression deformation of the coil spring 23 acts on the pedal 21 through the first movable member 221. The resistance force is recognized by the occupant as a reaction force against the depression operation. On the other hand, a difference occurs between the displacement amount of the first movable member 221 indicated by the first signal S1 and the displacement amount of the second movable member 222 indicated by the second signal S2.

[0075] Subsequently, the processor of the control device 26 causes the drive mechanism 25 to supply a driving force for displacing the second movable member 222 so as to eliminate the difference in the displacement amounts of the first movable member 221 and the second movable member 222. In other words, a driving force is supplied to the second movable member 222 so as to eliminate the compression deformation of the coil spring 23.

[0076] Specifically, the processor causes the drive mechanism 25 to transmit a driving force for displacing the second movable member 122 forward. That is, the processor outputs a control signal CS from the output interface to drive the motor 253 so that the second pinion gear 252 rotates clockwise when viewed from the right side of the pedal 21.

[0077] In order to eliminate the compressive deformation of the coil spring 23, the displacement speed of the second movable member 222 needs to be faster than that of the first movable member 221. The control signal CS is determined so that the rotational speed of the second pinion gear 252 can satisfy this requirement.

[0078] As a result, as illustrated in FIG. 9, both the first movable member 221 and the second movable member 222 are displaced forward while eliminating the compressive deformation of the coil spring 23. The processor of the control device 26 continues to monitor the first signal S1 and the second signal S2, and continues to drive the motor 253 until the displacement difference between the first movable member 221 and the second movable member 222 is eliminated. When it is determined that the rotation amount difference has been eliminated, the processor stops the drive of the motor 253.

[0079] When the drive of the motor 253 is stopped from the state where the displacement of the second movable member 222 illustrated in FIG. 8 is blocked, the second movable member 222 immediately displaces to eliminate the displacement difference from the first movable member 221 due to the elastic restoring force of the coil spring 23. In this case, the occupant feels that the reaction force felt at the beginning of the depressing operation of the pedal 21 is lost.

[0080] Therefore, by setting the displacement speed of the second movable member 222 to a speed lower than the displacement speed of the second movable member 222 accompanying the elastic restoration of the coil spring 23 without falling below the displacement speed of the first movable member 221, the reaction force to the depressing operation of the pedal 21 can be felt by the occupant. In other words, the feel of the pedal 21 can be adjusted according to the timing of releasing the displacement block of the second movable member 222 and the subsequent displacement speed of the second movable member 222.

[0081] As an example, by relatively quickly releasing the displacement prevention of the second movable member 222 and setting the displacement speed of the second movable member 222 relatively fast, the time until the difference in displacement amounts between the first movable member 221 and the second movable member 222 is eliminated becomes shorter, and a relatively light pedal feel of the pedal 21 can be created. As another example, by relatively slowly releasing the displacement prevention of the second movable member 222 and setting the rotation speed of the second movable member 222 relatively slow, the time until the difference in rotation amounts between the first movable member 221 and the second movable member 222 is eliminated becomes longer, and a relatively heavy pedal feel of the pedal 21 can be created.

[0082] That is, in the brake device 20 according to the present embodiment, with the depression operation of the pedal 21, a difference in displacement amount occurs between the first movable member 221 and the second movable member 222 through the compression deformation of the coil spring 23. By the drive mechanism 25 supplying a driving force to the second movable member 222 so as to adjust the difference in displacement amount, a pedal feel of the pedal 21 can be created without interposing a hydraulic mechanism. Since the interposition of the hydraulic mechanism can be made unnecessary, a brake-by-wire type brake device 20 capable of suppressing the enlargement and complication of the structure can be provided.

[0083] The displacement speed of the second movable member 222 may be constant or may vary. Particularly in the latter case, a more delicate pedal feel of the pedal 21 can be created with a high degree of freedom without interposing a hydraulic mechanism.

[0084] The pedal feel of the pedal 21 is also related to the stepping force of the occupant. The pedal feel created by setting the timing of releasing the displacement prevention of the second movable member 222 and the displacement speed of the second movable member 222 to specific values may feel heavy to an occupant with a weak stepping force, while it may feel light to an occupant with a strong stepping force. Therefore, the timing of releasing the displacement prevention of the second movable member 222 and the rotation speed of the second movable member 222 can be changed according to the stepping force of the occupant.

[0085] The depressing force of the occupant may correspond to the displacement amount per unit time of the first movable member 221 in the initial stage of the depressing operation of the pedal 21. Therefore, the processor of the control device 26 can detect the depressing force of the occupant by specifying the amount of rotation per unit time of the first movable member 221 based on the first signal S1.

[0086] As an example, the displacement of the second movable member 222 can be controlled so as to provide a constant feel regardless of the depressing force of the occupant. Specifically, when a relatively weak depressing force is detected, a relatively light feel can be created, and when a relatively strong depressing force is detected, a relatively heavy feel can be created, so that the displacement of the second movable member 222 can be controlled.

[0087] As another example, the control device 26 can receive an instruction from the occupant to select a preferred feel from a plurality of levels through a user interface (not shown) mounted on the vehicle. The control device 26 makes a setting related to the displacement of the second movable member 222 according to the instruction so that a feel according to the preference of the occupant is created.

[0088] According to such a configuration, creation of the feel of the pedal 21 according to the depressing force of the occupant can be realized without intervening a hydraulic mechanism.

[0089] The brake device 20 can have a failure detection function for each of the first sensor 241 and the second sensor 242.

[0090] As an example, as shown in FIG. 10, communication for failure detection can be performed between the control device 26, the first sensor 241, and the second sensor 242. Specifically, the control device 26 periodically transmits an inquiry signal for diagnosis to each of the first sensor 241 and the second sensor 242. Each of the first sensor 241 and the second sensor 242 is configured to transmit a response signal to the inquiry signal. When a response signal to the inquiry signal cannot be obtained from either the first sensor 241 or the second sensor 242, the control device 26 determines that the sensor is malfunctioning.

[0091] As another example, each of the first sensor 241 and the second sensor 242 may have a self-diagnosis function. When a signal indicating a failure is received from either the first sensor 241 or the second sensor 242, the control device 26 determines that the sensor is faulty.

[0092] Specifically, each of the first sensor 241 and the second sensor 242 is duplicated by two sensor elements with different outputs for the detected displacement amount of the movable member. For example, a sensor element that provides an output having a positive correlation with the detected displacement amount and a sensor element that provides an output having a negative correlation with the detected displacement amount are used. Each output is determined such that the sum of both outputs is constant regardless of the detected rotation angle, and the value of the sum is used for monitoring. When a failure occurs in either one of the sensor elements, the value of the sum deviates from a constant value, enabling self-diagnosis of the failure.

[0093] When a failure is detected in either the first sensor 241 or the second sensor 242, the control device 26 may be configured to cause the drive mechanism 25 to stop supplying a driving force to the second movable member 222. FIG. 11 illustrates the case where a failure is detected in the first sensor 241. Specifically, the control device 26 stops outputting the control signal CS for driving the motor 253. As a result, the second pinion gear 252 reaches a no-load state.

[0094] When the pedal 21 is depressed in this state, the second movable member 222 also displaces by the same amount following the displacement of the first movable member 221. Therefore, the second signal S2 reflects the operation amount of the pedal 21. The control device 26 outputs a braking signal BS that causes the braking system to perform braking of the moving body according to the operation amount of the pedal 21 based on the second signal S2. When a failure occurs in the second sensor 242, the braking signal BS may be output based on the first signal S1.

[0095] According to such a configuration, although the function of creating the feel of the pedal 21 by the drive mechanism 25 is invalidated, even if a failure occurs in either the first sensor 241 or the second sensor 242, the braking function essential for the brake-by-wire type brake device 20 can be ensured.

[0096] In addition, in order to enhance the robustness of the brake device 20 against failures, it is preferable that the first sensor 241 and the second sensor 242 are each supplied with power from a different system power source.

[0097] There may be a failure in which the motor 253 stops in a locked state while applying a load to the second pinion gear 252. The brake device 20 may be provided with a detection function for such a failure state. For example, as shown in FIG. 10, the control device 26 outputs a control signal CS for causing the motor 253 to perform a drive for slightly rotating the second pinion gear 252. When the displacement of the second movable member 222 based on the second signal S2 is not detected with respect to this control signal CS, it is determined that the motor 253 has stopped in a locked state.

[0098] In this case, the control device 26 is configured to output a braking signal BS for causing the braking system to brake the moving body within the range of the displacement amount difference between the first movable member 221 and the second movable member 222 caused by the compression deformation of the coil spring 23 accompanying the depression operation of the pedal 21.

[0099] According to such a configuration, although the function of creating the feel of the pedal 21 by the drive mechanism 25 is invalidated, even if a failure occurs in which the motor 253 stops in a locked state, the braking function essential for the brake-by-wire type brake device 20 can be ensured.

[0100] In addition, in order to enhance the robustness of the brake device 20 against failures, it is preferable that the motor 253 is supplied with power from a power source of a different system from each of the first sensor 241 and the second sensor 242.

[0101] In the present exemplary embodiment, the drive mechanism 25 supplies a driving force to the second movable member 222 so as to adjust to reduce the displacement difference between the first movable member 221 and the second movable member 222 that occurs as the coil spring 23 is compressed and deformed. However, the drive mechanism 225 may temporarily adjust to increase the displacement difference between the first movable member 221 and the second movable member 222 according to the feel of the pedal 21 created.

[0102] Processors having various functions described while referring to each exemplary embodiment can be realized by a general-purpose microprocessor that operates in cooperation with a general-purpose memory. Examples of the general-purpose microprocessor can include a CPU, an MPU, and a GPU. Examples of the general-purpose memory can include a ROM and a RAM. In this case, a computer program for realizing the function can be stored in the ROM. The ROM is an example of a non-transitory computer-readable medium that stores a computer program. The general-purpose microprocessor designates at least a part of the computer program stored on the ROM and expands it on the RAM, and executes the above-described processing in cooperation with the RAM. The above computer program may be pre-installed in the general-purpose memory, or may be downloaded from an external server via a communication network and installed in the general-purpose memory. In this case, the external server is an example of a computer-readable medium that stores a computer program.

[0103] The processor may also be realized by an application specific integrated circuit capable of executing the above computer program, such as a microcontroller, an ASIC, or an FPGA. In this case, the above computer program is pre-installed in a storage element included in the application specific integrated circuit. The storage element is an example of a computer-readable medium that stores a computer program. The processor can also be realized by a combination of a general-purpose microprocessor and an application specific integrated circuit.

[0104] Each of the configurations described so far is merely an example for facilitating the understanding of the present disclosure. Each configuration example can be appropriately modified and combined with other configuration examples without departing from the gist of the present disclosure.

[0105] The braking device according to each of the above-described embodiment examples has a so-called suspended type configuration in which the first rotation axis A1 is located above the upper end of the pedal surface on which the feet of the occupant are placed. However, like a pedal device having a so-called floor-mounted type configuration, the first rotation axis A1 can be disposed below the upper end of the pedal surface.

[0106] The braking device according to each of the above-described embodiment examples can also be mounted on a moving body other than a vehicle. Examples of other moving bodies include railways, airplanes, ships, and the like.

[0107] Each of the configurations listed below also constitutes a part of the present disclosure. Item 1: A pedal that is displaced about a first rotation axis by a stepping operation to brake a moving body, A first movable member that is displaceable together with the pedal, A second movable member that is displaceable independently of the pedal, An elastic member that connects the first movable member and the second movable member and allows relative displacement between the first movable member and the second movable member by elastic deformation, A first sensor that outputs a first signal corresponding to the displacement amount of the first movable member, A second sensor that outputs a second signal corresponding to the displacement amount of the second movable member, A drive mechanism that supplies a driving force for adjusting the difference between the displacement amount of the first movable member and the displacement amount of the second movable member to the second movable member based on the first signal and the second signal, and a braking device. Item 2: The first movable member and the second movable member are displaceable about a second rotation axis extending parallel to the first rotation axis. The braking device according to item 1. Item 3: The first movable member and the second movable member are displaceable in a direction intersecting the first rotation axis. The braking device according to item 1. Item 4: When a failure is detected in one of the first sensor and the second sensor, the drive mechanism stops supplying the driving force. The braking device according to any one of items 1 to 3. Item 5: When a failure is detected in the motor, braking of the moving body is performed based on the difference between the displacement amount of the first movable member and the displacement amount of the second movable member. The braking device according to any one of items 1 to 4.

Description of reference numerals

[0108] 10: Braking device, 11: Pedal, 121: First movable member, 122: Second movable member, 13: Torsion bar, 141: First sensor, 142: Second sensor, 15: Drive mechanism, 20: Braking device, 21: Pedal, 221: First movable member, 222: Second movable member, 23: Coil spring, 241: First sensor, 242: Second sensor, 25: Drive mechanism, A1: First rotation axis, A2: Second rotation axis, S1: First signal, S2: Second signal

Claims

1. A pedal that is displaced about a first pivot axis by a depressing operation to brake a moving body, A first movable member displaceable together with the pedal, A second movable member displaceable independently of the pedal, An elastic member that connects the first movable member and the second movable member and allows relative displacement between the first movable member and the second movable member by elastic deformation, A first sensor that outputs a first signal corresponding to the displacement amount of the first movable member, A second sensor that outputs a second signal corresponding to the displacement amount of the second movable member, A drive mechanism that supplies a driving force for adjusting the difference between the displacement amount of the first movable member and the displacement amount of the second movable member to the second movable member based on the first signal and the second signal, Comprising, A braking device.

2. The first movable member and the second movable member are displaceable about a second pivot axis extending parallel to the first pivot axis, The braking device according to Claim 1.

3. The first movable member and the second movable member are displaceable in a direction intersecting the first pivot axis, The braking device according to Claim 1.

4. When a failure is detected in one of the first sensor and the second sensor, the drive mechanism stops supplying the driving force, The braking device according to Claim 1.

5. When a failure is detected in the drive mechanism, the moving body is braked based on the difference between the displacement amount of the first movable member and the displacement amount of the second movable member, The braking device according to Claim 1.

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