Brake assist device

Abstract

To bring a vehicle into a brake applied state so as to enable stopping at an early stage when a motor stops operating.SOLUTION: A brake assist device 100 comprises: a sheave 30 to which a wire 32 with one end connected to a brake pedal 80 is connected via the other end of the wire, and which can adjust brake force by rotating to wind the wire 32; a motor 10 that causes the sheave 30 to rotate; a rotary body 40 that is attached to the sheave 30 and is rotatable integrally with the sheave 30; an electromagnetic clutch 50 that switches between a non-rotatable state of making rotary body 40 non-rotatable so that only the sheave 30 is caused to rotate by the motor 10 and a rotatable state of making the rotary body 40 rotatable so that the sheave 30 and the rotating body 40 are caused to integrally rotate; and a biasing unit 60 that rotationally biases the rotary body 40 in a direction for the sheave 30 to wind the wire 32 and, when the motor 10 does not operate to bring the rotary body 40 into the non-rotatable state, causes the rotary body 40 and the sheave 30 to rotate in the winding direction.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a brake assist device.

Background Art

[0002] In recent years, the development of autonomous driving that automatically controls the operation of the accelerator, brake, and / or steering wheel has been underway. For example, an adaptive cruise control that automatically controls both the accelerator operation and the brake operation is known. Even when the vehicle is traveling in autonomous driving, a technique has been proposed that enables an instantaneous switch to manual operation when a manual operation is performed according to the driver's will (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the brake operation is automatically controlled, if the motor for generating the braking force fails to operate due to a power loss or the like, the brake is not applied. At this time, for example, if the driver cannot perform a manual operation for some reason, the vehicle will coast.

[0005] The present invention has been made in view of the above problems, and an object thereof is to enable the vehicle to stop early with the brake applied when the motor fails to operate.

Means for Solving the Problems

[0006] The present invention relates to a brake assist device including: a sheave to which the other end of a wire whose one end is connected to a brake pedal is connected, and which can adjust a braking force by rotating to wind up the wire; a motor that rotates the sheave; a rotating body attached to the sheave and rotatable integrally with the sheave; a non-rotatable state in which only the sheave among the sheave and the rotating body is rotated by the motor, and the rotating body is made non-rotatable; a rotatable state in which the sheave and the rotating body are rotated integrally, and the rotating body is made rotatable; an electromagnetic clutch that switches between the non-rotatable state and the rotatable state; and a biasing portion that biases the rotating body to rotate in a direction in which the sheave winds up the wire, and rotates the rotating body and the sheave in the winding direction when the motor does not operate and the rotating body is in the rotatable state.

Advantages of the Invention

[0007] According to the present invention, a vehicle can be stopped early, and safety can be ensured.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Embodiment

[0010] FIG. 1(a) is a perspective view of a brake assist device 100 according to an embodiment, and FIGS. 1(b) and 1(c) are cutaway perspective views of the brake assist device 100. In FIGS. 1(a) and 1(b), for clarity of the drawing, the rotating body 40 is hatched. As shown in FIGS. 1(a) to 1(c), the brake assist device 100 includes a motor 10, a speed reducer 20, a sheave 30, a rotating body 40, an electromagnetic clutch 50, and a biasing portion 60.

[0011] One end of a wire 32 whose other end is connected to a brake pedal 80 is connected to the sheave 30. The sheave 30 is rotated by the motor 10 and winds up the wire 32 by rotating. The rotation direction in which the sheave 30 winds up the wire 32 is defined as the CCW direction, and the opposite rotation direction is defined as the CW direction. The wire 32 is wound up by the sheave 30 to pull the brake pedal 80. Thereby, a braking force is generated. Since the amount by which the brake pedal 80 is pulled by the wire 32 (in other words, the amount of depression of the brake pedal 80) changes according to the amount of winding of the wire 32 by the sheave 30, the magnitude of the braking force changes. Therefore, the magnitude of the braking force can be adjusted by adjusting the amount of winding of the wire 32 by the sheave 30.

[0012] The motor 10 is connected to the sheave 30 via the speed reducer 20 and rotates the sheave 30. The motor 10 operates by electric power supplied from a motor driver provided in the control device 70. The control device 70 controls the electric power supplied to the motor 10 based on, for example, a signal from a sensor provided in a vehicle, and adjusts the amount of winding of the wire 32 by the sheave 30. Thereby, automatic control of a braking operation such as, for example, adaptive cruise control becomes possible. The control device 70 is, for example, an ECU (Electronic Control Unit).

[0013] The rotating body 40 is attached to the sheave 30 and can rotate integrally with the sheave 30. An electromagnetic clutch 50 is provided adjacent to the rotating body 40. The electromagnetic clutch 50 is located on the side opposite to the sheave 30 with respect to the rotating body 40. The electromagnetic clutch 50 is fixed to the pedestal 82. Further, the speed reducer 20 is fixed to a wall portion 84 extending vertically from the pedestal 82 and is connected to the sheave 30.

[0014] Based on the engagement signal sent by the control device 70 to the electromagnetic brake relay 72, the electromagnetic clutch 50 switches between a non-rotatable state in which the rotation of the rotating body 40 is disabled and a rotatable state in which rotation is possible. The rotating body 40 engages with the electromagnetic clutch 50 in the non-rotatable state and is released from the electromagnetic clutch 50 in the rotatable state. When the rotating body 40 is in the non-rotatable state, only the sheave 30 rotates by the motor 10. When the rotating body 40 is in the rotatable state, the sheave 30 and the rotating body 40 rotate integrally.

[0015] An urging portion 60 is connected to the rotating body 40. The urging portion 60 includes a compression spring 62 and a wire 64. One end of the compression spring 62 contacts a fixing member 86 fixed to the pedestal 82, and the other end contacts a pressing member 88, and it is provided compressed between the fixing member 86 and the pressing member 88. One end of the wire 64 is connected to the rotating body 40, and the other end side is fixed to the pressing member 88. Since the fixing member 86 is fixed to the pedestal 82, a force in a direction away from the fixing member 86 is applied to the pressing member 88 by the compression spring 62. Therefore, the wire 64 fixed to the pressing member 88 is pulled in a direction from the fixing member 86 toward the pressing member 88, and a force is applied to rotate the rotating body 40 in the CCW direction in which the sheave 30 winds up the wire 32. In this way, the urging portion 60 rotationally urges the rotating body 40 in the CCW direction in which the sheave 30 winds up the wire 14.

[0016] Figures 2(a) to 2(c) are cross-sectional views showing the operation of the brake assist device 100 according to the embodiment, and Figures 2(d) to 2(f) are graphs showing the relationship between the rotation angle and the generated force in the case of Figures 2(a) to 2(c). In the following description, it is assumed that the sheave 30 and the rotating body 40 are in the initial position (rotation angle is 0 [°]) and the rotating body 40 is in a non-rotatable state, and a rotational torque of 300 [N] for rotating the rotating body 40 in the CCW direction is generated by the biasing portion 60.

[0017] Figures 2(a) and 2(d) show the case where the rotational torque of the motor 10 is zero and the electromagnetic clutch 50 is OFF, and the rotating body 40 is in a rotatable state. As shown in Figures 2(a) and 2(d), with the rotational torque of the motor 10 being zero and the rotating body 40 being in a rotatable state, the sheave 30 and the rotating body 40 rotate in the CCW direction by the rotational torque of 300 [N] from the biasing portion 60. When the sheave 30 and the rotating body 40 rotate in the CCW direction, the brake pedal 80 is pulled by the wire 32. Finally, the force with which the biasing portion 60 rotates the rotating body 40 in the CCW direction and the force with which the brake pedal 80 rotates the sheave 30 in the CW direction via the wire 32 both become 150 N and balance each other. At this time, the sheave 30 and the rotating body 40 rotate approximately 15 [°] in the CCW direction from the initial position. Here, the force with which the biasing portion 60 rotates the rotating body 40 is referred to as the "spring force", and the force with which the wire 32 pulls the brake pedal 80 (corresponding to the force with which the driver depresses the brake pedal 80) is referred to as the "foot brake force". The force with which the wire 32 pulls the brake pedal 80 due to the rotation of the sheave 30 is equal to the force with which the brake pedal 80 rotates the sheave 30 via the wire 32. Therefore, in Figure 2(d), both the spring force and the foot brake force are 150 [N].

[0018] Figures 2(b) and 2(e) show the case where, with the brake pedal 80 returned to the origin position and the rotating body 40 remaining rotatable, a rotational torque of 300 N is applied in the CW direction by the motor 10. As shown in Figures 2(b) and 2(e), by applying a rotational torque of 300 [N] in the CW direction by the motor 10, the sheave 30 and the rotating body 40 return to the initial position with a rotation angle of 0 [°], and the force (spring force) with which the biasing portion 60 rotates the rotating body 40 in the CCW direction and the force (motor force) with which the motor 10 rotates the sheave 30 and the rotating body 40 in the CW direction both become 300 [N]. Since the brake pedal 80 is at the origin position where it is not pulled by the wire 32, the foot brake force is 0 [N]. After the brake pedal 80 reaches the origin position, the control device 70 transmits an engagement signal to turn on the electromagnetic clutch 50 and make the rotating body 40 non-rotatable.

[0019] Here, for example, the control device 70 may obtain the rotational position of the rotor of the motor 10 from the motor driver, and when the change amount of the rotor position is equal to or less than a predetermined value (for example, when the encoder count is 10 counts or less compared to the previous time in Figures 2(b) and 2(e)), it may be determined that the rotational control of the sheave 30 and the rotating body 40 in the CW direction has been performed normally.

[0020] Figures 2(c) and 2(f) show the case where the automatic control of the braking operation is performed by the motor 10. As shown in Figures 2(c) and 2(f), since the rotating body 40 is engaged with the electromagnetic clutch 50 and is in a non-rotatable state, only the sheave 30 rotates by the motor 10. In Figure 2(f), the force that makes the electromagnetic clutch 50 put the rotating body 40 in a non-rotatable state is illustrated as the "electromagnetic braking force". In this case, for example, the automatic control of the braking operation such as adaptive cruise control is performed, and the power supplied to the motor 10 is controlled based on the signal from the sensor provided in the vehicle. Thereby, a force (motor force) for the motor 10 to rotate the sheave 30 is generated, and the sheave 30 rotates in the CCW direction to wind up the wire 32, so that the brake pedal 80 is pulled by the wire 32 and a foot braking force is generated. Thereby, a braking force of an appropriate magnitude can be generated based on the signal from the sensor, and the automatic control of the braking operation can be performed.

[0021] Here, assume a case where the motor 10 stops operating due to power loss or the like during the automatic control of the braking operation in Figures 2(c) and 2(f), and the automatic control of the braking operation becomes impossible. For example, when the power supply of the motor 10 is lost, the power supply of the electromagnetic clutch 50 is also designed to be lost. Therefore, when the motor 10 stops operating due to power loss or the like, the electromagnetic clutch 50 turns off and the rotating body 40 becomes rotatable. That is, the rotational torque of the motor 10 is zero, and the rotating body 40 is in a rotatable state. This state is the state shown in Figures 2(a) and 2(d). That is, when the motor 10 stops operating due to power loss or the like, it transitions from the state of Figures 2(c) and 2(f) to the state of Figures 2(a) and 2(d).

[0022] In the states of FIGS. 2(a) and 2(d), as described above, due to the force (spring force) by which the biasing portion 60 rotates the rotating body 40 in the CCW direction, a force (foot brake force) by which the wire 32 pulls the brake pedal 80 is generated. Thus, since the foot brake force is generated, even when the motor 10 stops operating, the vehicle is braked and stops early.

[0023] As described above, in the embodiment, the other end of the wire 32 whose one end is connected to the brake pedal 80 is connected to a sheave 30 that can adjust the braking force by rotating and winding the wire 32, and a rotating body 40 that can rotate integrally with the sheave 30 is attached to the sheave 30. A non-rotatable state in which only the sheave 30 of the sheave 30 and the rotating body 40 is rotated by the motor 10 and the rotating body 40 is non-rotatable, and a rotatable state in which the sheave 30 and the rotating body 40 rotate integrally and the rotating body 40 is rotatable are switched by an electromagnetic clutch 50. When the motor 10 does not operate and the rotating body 40 is in the rotatable state, the rotating body 40 and the sheave 30 rotate in the direction of winding the wire 32 by a biasing portion 60 that rotationally biases the rotating body 40 in the direction in which the sheave 30 winds the wire 32. With such a configuration, as shown in FIGS. 2(a) to 2(f), even when the motor 10 that rotates the sheave 30 stops operating due to a power loss or the like, a foot brake force can be generated, and the vehicle can be stopped early to ensure safety.

[0024] Figures 3(a) and 3(b) are examples of engagement signals transmitted by the control device 70 to control the ON and OFF of the electromagnetic clutch 50. The engagement signal may be an ON / OFF signal for controlling ON / OFF as shown in Fig. 3(a), or may be a watchdog signal composed of a periodic pulse signal as shown in Fig. 3(b). When using the watchdog signal, if the Hi and Lo pulse signals continue, the electromagnetic clutch 50 is turned ON. When using the watchdog signal, if a failure occurs in the control device 70, the Hi or Lo signal will continue to be output, so the electromagnetic clutch 50 will turn OFF. Therefore, the rotating body 40 becomes rotatable, and as shown in Figs. 2(a) and 2(d), the foot brake force by the biasing portion 60 can be generated, so that the vehicle can be stopped early and safety can be ensured. Determining the ON and OFF of the electromagnetic clutch 50 from the watchdog signal may be performed using a determiner by a circuit or a microcomputer.

[0025] Figure 3(c) is a cutaway perspective view when the manual release portion 90 is provided in the brake assist device 100 according to the embodiment. As shown in Fig. 3(c), the manual release portion 90 includes a handle 92 and a wire 94 having one end connected to the handle 92 and the other end connected to the rotating body 40. By operating the handle 92 (for example, by pulling the handle 92 upward), the rotating body 40 can be rotated in the CW direction by the wire 94. Therefore, for example, when the electromagnetic clutch 50 is OFF and the foot brake force by the biasing portion 60 is generated during parking or the like, the foot brake force can be made zero by operating the handle 92. When the foot brake force is generated, hydraulic pressure is generated in the brake oil, but by operating the handle 92 to make the foot brake force zero, the hydraulic pressure of the brake oil can be released, and deterioration of the brake oil piping can be suppressed. Also, for example, the danger caused by the hydraulic pressure of the brake oil during maintenance work or the like can be avoided.

[0026] In addition, in the embodiment, the biasing unit 60 may be a hydraulic mechanism instead of the compression spring 62. Further, in the embodiment, the case of an automatic operation for automatically controlling the braking operation is shown as an example, but the present invention is not limited to this case, and it can also be applied to cases other than the automatic operation in which the driver performs the braking operation by stepping on the brake pedal 80. Even in this case, the foot braking force can be generated when there is an unintended power loss by the driver.

[0027] As described above, the embodiments of the present invention have been described in detail. However, the present invention is not limited to such specific embodiments, and various modifications and changes are possible within the scope of the gist of the present invention described in the claims.

Explanation of Reference Numerals

[0028] 10… motor, 20… reducer, 30… sheave, 32… wire, 40… rotating body, 50… electromagnetic clutch, 60… biasing unit, 62… compression spring, 64… wire, 70… control device, 72… electromagnetic brake relay, 80… brake pedal, 82… pedestal, 84… wall portion, 86… fixing member, 88… pressing member, 90… manual release portion, 92… handle, 94… wire, 100… brake assist device

Claims

【Claim 1】 A sheave to which the other end of a wire having one end connected to a brake pedal is connected, and which can adjust the braking force by rotating and winding up the wire; A motor for rotating the sheave; A rotating body attached to the sheave and rotatable integrally with the sheave; An electromagnetic clutch that switches between a non-rotatable state in which only the sheave of the sheave and the rotating body is rotated by the motor and a rotatable state in which the sheave and the rotating body rotate integrally; A brake assist device comprising a biasing portion that biases the rotating body in the direction in which the sheave winds up the wire and rotates the rotating body and the sheave in the winding-up direction when the motor does not operate and the rotating body is in the rotatable state.

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