JP2019031130A - Vehicle braking apparatus and vehicle braking method - Google Patents

Abstract

To provide a vehicle braking apparatus capable of improving deterioration of fuel consumption while securing safety of vehicle stop state.SOLUTION: A vehicle braking apparatus 1000 comprises: a torque sensor (detector) 42 which detects torque of rotation axis transmitting power of an engine mounted in a vehicle to a driving wheel; a torque acquisition unit 300awhich acquires torque detected by the torque sensor (detector) 42 as vehicle stop state torque in a vehicle stop state; and a brake control unit 300a which controls brake force applied to the driving wheel based on comparison result obtained by comparing the vehicle stop state torque with torque detected by the torque sensor (detector) 42 after acquisition of the vehicle stop state torque.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a vehicle braking device and a vehicle braking method for braking a vehicle.

  In Patent Document 1, when the driver performs a brake operation and detects the stop of the vehicle, the brake control unit changes the brake pressure corresponding to the driver's brake operation amount to a brake pressure higher than the brake pressure. There is a disclosure about the control technology. According to Patent Document 1, since the brake pressure is controlled to be higher than the brake pressure corresponding to the driver's brake operation amount, safety can be ensured even when the vehicle stops on a slope.

JP 2000-168520 A

  However, when the brake mechanism of the vehicle is, for example, a mechanism that opens the brake pad with a spring, if the brake pressure is increased as in Patent Document 1, the brake pad may not return with the strength of the spring. .

  As described above, when the brake pad does not return due to the strength of the spring, the brake pad is pressed against the brake rotor even during traveling, and there is a problem that fuel consumption deteriorates.

  Accordingly, an object of the present invention is to provide a vehicle braking device and a vehicle braking method capable of improving the deterioration of fuel consumption while ensuring safety in a vehicle stop state.

  In order to solve the above-described problems, a vehicle braking apparatus according to the present invention includes a detection unit that detects torque of a rotating shaft that transmits power of a prime mover provided in a vehicle to drive wheels, and a vehicle stop state in which the vehicle is stopped. A comparison result of comparing the torque acquisition unit that acquires the torque detected by the detection unit as a vehicle stop state torque, the vehicle stop state torque, and the torque that the detection unit detects after acquiring the vehicle stop state torque And a control unit that controls a braking force applied to the drive wheel.

  The control unit may reduce the braking force when there is no change in the torque detected by the detection unit.

  The control unit may reduce the braking force until the torque detected by the detection unit is smaller than the vehicle stop state torque.

  The control unit may increase the braking force when the torque detected by the detection unit decreases.

  The control unit may increase the braking force until the torque detected by the detection unit increases when the torque detected by the detection unit becomes smaller than the vehicle stop state torque.

  The control unit may hold the braking force when the torque detected by the detection unit increases.

  The control unit may hold the braking force when the braking force becomes a predetermined value or less without changing the torque detected by the detection unit.

  The vehicle has a braking operation member for a driver to operate the braking force, and the control unit is configured to perform the braking when an operation amount of the braking operation member is a predetermined amount or more in the vehicle stop state. The braking force may be maintained regardless of the operation amount of the operation member.

  The control unit may increase the braking force when the torque detected by the detection unit is reduced after holding the braking force.

  In order to solve the above-described problems, a vehicle braking method according to the present invention includes a step of detecting torque of a rotating shaft that transmits power of a prime mover provided in a vehicle to driving wheels, and a vehicle stop in which the vehicle is stopped. A result of comparing the step of acquiring the torque detected by the detection unit as a vehicle stop state torque in the state, the vehicle stop state torque, and the torque detected by the detection unit after acquiring the vehicle stop state torque And a step of controlling a braking force applied to the drive wheel.

  ADVANTAGE OF THE INVENTION According to this invention, the deterioration of a fuel consumption can be improved, ensuring the safety | security of a vehicle stop state.

It is a figure which shows the structure of a vehicle. It is a figure explaining the structure of the control system of a vehicle. It is a flowchart for demonstrating a vehicle braking process.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

  FIG. 1 is a diagram illustrating a configuration of the vehicle 1. As shown in FIG. 1, the vehicle 1 is a so-called hybrid vehicle having an engine 2 and a motor 4 as a prime mover. Here, a hybrid vehicle will be described as an example of the vehicle 1, but an electric vehicle or a motor-free vehicle may be applied as the vehicle 1. In FIG. 1, the signal flow is indicated by solid arrows.

  The engine 2 is a gasoline engine or a diesel engine. Based on the control of the vehicle control device 38, the engine 2 obtains a driving force by burning fuel supplied from a fuel tank (not shown), and the obtained driving force is obtained. Output to the damper 10.

  The motor 4 is connected to the driving battery 14 of the vehicle 1 via the inverter 12, receives electric power from the battery 14, and transmits driving force to the rotating shaft 16. Further, the motor 4 functions as a generator that generates power by regeneration by applying a braking force to the vehicle 1 instead of the brake mechanism 18 or together with the brake mechanism 18 when the vehicle 1 is decelerated.

  The generator 6 is connected to the battery 14 via the inverter 12 and stores in the battery 14 the electric power generated by receiving the driving force from the engine 2 via the power split mechanism 20 described later. The generator 6 may supply the generated power to the motor 4 in some cases. Furthermore, the generator 6 also functions as an electric motor (motor) at a timing different from that of power generation, and is driven by electric power supplied from the battery 14 via the inverter 12.

  As the power split mechanism 20, for example, a planetary gear mechanism including a sun gear, a ring gear, a planetary gear, and a carrier is applied. The sun gear is connected to the rotating shaft of the generator 6, the ring gear is connected to the rotating shaft 16, and the carrier is connected to the engine 2 via the damper 10. In the power split mechanism 20, for example, the driving force transmitted from the engine 2 via the damper 10 is split and transmitted to the generator 6 and the rotating shaft 16. The rotating shaft 16 and the propeller shaft 22 are provided with gear mechanisms 24 a and 24 b, respectively, and the gear mechanisms 24 a and 24 b transmit driving force from the rotating shaft 16 to the propeller shaft 22.

  The driving force obtained by the engine 2 and the motor 4 is converted into the front wheel (driving wheel) as the driving force through the rotating shaft 16, the gear mechanisms 24a and 24b, the propeller shaft 22, the front differential gear 26, and the front wheel drive shaft (rotating shaft) 28. ) 30. The power obtained by the engine 2 and the motor 4 is transmitted to a rear wheel (drive wheel) 36 via a rotary shaft 16, gear mechanisms 24 a and 24 b, a propeller shaft 22, a rear differential gear 32, and a rear wheel drive shaft 34. Also transmitted as driving force.

  The vehicle 1 also has a brake pedal (braking operation member) BP for operating a brake pressure (braking force) applied to the front wheels 30 and the rear wheels 36 by the driver. The driver can operate the brake pressure applied to the front wheel 30 and the rear wheel 36 by the brake mechanism 18 by depressing the brake pedal BP with his / her foot or releasing the foot from the brake pedal BP.

  In this embodiment, the brake mechanism 18 is, for example, a disc brake mechanism. The brake mechanism 18 includes a brake rotor, a set of brake pads, a piston, and a spring. The brake rotor is fixed to the front wheel 30 and the rear wheel 36 of the vehicle 1 so as to rotate together with the front wheel 30 and the rear wheel 36 of the vehicle 1. The set of brake pads is provided on both sides of the brake rotor at a distance from the brake rotor. The brake pad is connected to one or more pistons that are hydraulically or pneumatically actuated, and moves from the non-braking position to the braking position by being pressed from the piston. When the driver depresses the brake pedal BP with his / her foot, the brake pad moves from the non-braking position to the braking position by the operation of the piston, and frictionally engages the opposing braking surface of the brake rotor. When the brake pad frictionally engages with the brake rotor, the rotation of the front wheel 30 and the rear wheel 36 can be slowed, and the rotation of the front wheel 30 and the rear wheel 36, that is, the vehicle 1 can be stopped. When the driver removes his / her foot from the brake pedal BP, the brake pad opens with the force of the spring and moves from the braking position to the non-braking position so as to move away from the brake rotor (so that the frictional engagement is released). To do.

  FIG. 2 is a diagram illustrating the configuration of the control system of the vehicle 1. The vehicle control device 38 is configured by a semiconductor integrated circuit including a central processing unit (CPU), a ROM storing a program, a RAM as a work area, and the like, and comprehensively controls each part of the vehicle 1. The vehicle control device 38 includes an ECU (Engine Control Unit) 100, an MCU (Motor Control Unit) 200, and a VDC (Vehicle Dynamics Control) 300. The vehicle control device 38 is connected to a vehicle speed sensor 40, a torque sensor (detection unit) 42, a brake pedal sensor 44, an accelerator pedal sensor 46, and a shift position sensor 48, and signals indicating values detected by the sensors are set at predetermined intervals. Input every time.

  The vehicle speed sensor 40 detects the vehicle speed of the vehicle 1 and transmits a vehicle speed signal indicating the vehicle speed to the vehicle control device 38. The torque sensor 42 is a strain gauge in the present embodiment, and is provided, for example, on the front wheel drive shaft 28 and transmits a torque signal indicating torque applied to the front wheel drive shaft 28 to the vehicle control device 38. The brake pedal sensor 44 detects the depression amount (brake depression amount) of the brake pedal BP, and transmits a brake depression amount signal (brake instruction) indicating the brake depression amount to the vehicle control device 38. The accelerator pedal sensor 46 detects an accelerator pedal depression amount (accelerator depression amount), and transmits an accelerator depression amount signal indicating the accelerator depression amount to the vehicle control device 38. The shift position sensor 48 detects the shift position (forward position (D range), reverse position (R range), neutral position (N range), parking position (P range)) of the shift lever, and indicates the shift position. A signal is transmitted to the vehicle control device 38.

  The ECU 100 is composed of a semiconductor integrated circuit including a central processing unit (CPU), a ROM storing programs, a RAM as a work area, and the like, and controls the engine 2. Specifically, the ECU 100 refers to a prestored map based on the accelerator depression amount signal transmitted from the accelerator pedal sensor 46 and the vehicle speed signal transmitted from the vehicle speed sensor 40, and the target torque of the engine 2 And the target engine speed is derived. Then, ECU 100 drives engine 2 so as to achieve the derived target torque and target engine speed.

  The MCU 200 is configured by a semiconductor integrated circuit including a central processing unit (CPU), a ROM storing a program, a RAM as a work area, and the like, and controls driving of the motor 4 and the generator 6 or power generation via the inverter 12. To do.

  The VDC 300 is composed of a semiconductor integrated circuit including a central processing unit (CPU), a ROM storing a program, a RAM as a work area, and the like. The VDC 300 includes a brake control unit 300a, and the brake control unit 300a Control. Specifically, the brake control unit 300a controls the brake pressure applied to the front wheels 30 and the rear wheels 36, that is, the brake mechanism 18, based on the brake depression amount signal transmitted from the brake pedal sensor 44. Further, as will be described in detail later, the brake control unit 300a applies a brake mechanism so that a brake pressure different from the brake pressure based on the brake depression amount signal transmitted from the brake pedal sensor 44 is applied to the front wheels 30 and the rear wheels 36. 18 is controlled.

The brake control unit 300 a includes a torque acquisition unit 300 a ₁ that acquires a torque signal transmitted from the torque sensor 42. The brake control unit 300a includes a vehicle speed acquisition unit 300a ₂ to obtain a vehicle speed signal sent from the vehicle speed sensor 40. The brake control unit 300a includes a storage unit (not illustrated), for example, can be stored (held) a torque signal obtained from the torque obtaining section 300a _1.

  In the present embodiment, the vehicle braking device 1000 that brakes the vehicle includes the brake mechanism 18, the vehicle speed sensor 40, the torque sensor 42, the brake pedal sensor 44, and the brake control unit 300a. The vehicle braking device 1000 can brake the vehicle 1 by the brake control unit 300a receiving various sensor signals and controlling the brake mechanism 18.

  Hereinafter, vehicle braking processing when the brake pedal BP is depressed while the vehicle 1 is traveling and the vehicle 1 is braked will be described in detail. FIG. 3 is a flowchart for explaining the vehicle braking process.

  When the brake pedal BP is depressed while the vehicle 1 is traveling and a brake depression amount signal is transmitted from the brake pedal sensor 44, the brake control unit 300a performs a brake mechanism based on the brake depression amount indicated by the brake depression amount signal. 18 is activated. Thereby, the vehicle 1 is braked.

The brake control unit 300a includes a vehicle speed signal detected by the vehicle speed sensor 40, and obtains via the vehicle speed acquisition unit 300a _2, whether the vehicle speed of the vehicle 1 is 0 stopped whether (vehicle 1 is (zero) Is determined (step S101). When the vehicle speed is 0 (YES in step S101), the brake control unit 300a determines that the vehicle 1 is stopped (stopped), and proceeds to step S102. If the vehicle speed is not zero (NO in step S101), the brake control unit 300a determines that the vehicle 1 is moving, and repeats the process in step S101 until the vehicle speed becomes zero.

When the brake control unit 300a determines that the vehicle 1 is stopped (the vehicle is in a stopped state), the torque acquisition unit outputs a torque (vehicle stopped state torque) signal of the front wheel drive shaft 28 detected by the torque sensor 42. to get through 300a ₁ (step S102). At this time, the brake control unit 300a stores the acquired signal (vehicle stop state torque) in a storage unit (not shown).

  The brake control unit 300a performs control such that the brake pressure decreases from the brake pressure (braking force) when it is determined that the vehicle 1 is stopped (step S103).

The brake control unit 300a is, after reducing the brake pressure, has been a front wheel drive shaft 28 torque (after reduction braking force torque) signal detected by the torque sensor 42, to get through the torque obtaining section 300a ₁ (step S104 ).

  The brake control unit 300a determines whether or not the torque signal detected by the torque sensor 42 has changed (for example, has changed to a small value). Specifically, the brake control unit 300a compares the braking force-reduced torque with the vehicle stop state torque stored in a storage unit (not shown). Then, as a result of the comparison, the brake control unit 300a determines whether or not the braking force reduced torque is smaller than the vehicle stop state torque (step S105). If the torque after braking force reduction is smaller than the vehicle stop state torque (YES in step S105), the brake control unit 300a determines that the vehicle 1 shifts from the stop state to the movable state, and proceeds to step S107. Note that when the vehicle 1 shifts from a stopped state to a movable state, torque transmission loss occurs in the tires of the front wheels 30 and the rear wheels 36. Therefore, the vehicle 1 starts to move immediately unless the brake pressure is reduced below that time. Never do. If the post-braking force reduced torque is greater than or equal to the vehicle stop state torque (NO in step S105), the brake control unit 300a determines that the vehicle 1 is maintaining the stop state, and proceeds to step S106.

  The brake control unit 300a determines whether or not the brake pressure (braking force) after decreasing the brake pressure is equal to or less than a predetermined value (step S106). Here, the predetermined value is, for example, 0 (zero). Thus, in the present embodiment, the brake control unit 300a determines whether or not the brake pressure has become 0 as a result of reducing the brake pressure. However, the predetermined value may be a value slightly larger than 0, for example, a value that is 5% of the maximum brake pressure of the vehicle 1. When the brake pressure after the brake pressure is reduced is equal to or lower than the predetermined value (YES in step S106), the brake control unit 300a stops the vehicle 1 on the uphill road surface and moves backward on the uphill due to a creep phenomenon. It is determined that the force to be attempted and the force to be advanced are balanced, and the process proceeds to step S110. On the other hand, when the brake pressure (braking force) after decreasing the brake pressure is larger than the predetermined value (NO in step S106), the brake control unit 300a returns to step S103 and performs the processing from step S103 to step S105 again.

  The brake control unit 300a performs control such that the brake pressure increases from the brake pressure when it is determined that the torque after braking force reduction is smaller than the vehicle stop state torque (step S107).

The brake control unit 300a is, after having increased brake pressure, it has been a front wheel drive shaft 28 torque (the increased braking force torque) signal detected by the torque sensor 42, to get through the torque obtaining section 300a ₁ (step S108 ).

  The brake control unit 300a determines whether or not the torque signal detected by the torque sensor 42 has changed (for example, has changed to a large value). Specifically, the brake control unit 300a compares the increased torque after braking with the vehicle stop state torque stored in a storage unit (not shown). Then, as a result of the comparison, the brake control unit 300a determines whether or not the increased braking force torque is equal to or greater than the vehicle stop state torque (step S109). Here, the brake control unit 300a determines whether or not the increased braking force torque is increased by increasing the brake pressure from the reduced braking force torque that is smaller than the vehicle stopped state torque, and is greater than or equal to the vehicle stopped state torque. Determine. When the braking force increase torque is equal to or greater than the vehicle stop state torque (YES in step S109), the brake control unit 300a determines that the vehicle 1 has shifted from the movable state to the stop state, and proceeds to step S110. Further, the brake control unit 300a determines that the vehicle 1 remains in a movable state when the torque after the increase of the braking force is less than the vehicle stop state torque (NO in step S109), returns to step S107, and returns to step S107. And the process of step S108 is performed again.

  The brake control unit 300a holds the brake pressure when it is determined that the torque after increasing the braking force is equal to or greater than the vehicle stop state torque, or the brake pressure when the brake pressure reaches a predetermined value or less (step S110).

  The brake control unit 300a determines whether or not the opening degree of the brake pedal BP is larger than 0 (zero) (step S111). When the opening degree of the brake pedal BP is greater than 0 (YES in step S111), the brake control unit 300a does not increase or decrease the brake pressure according to the change in the opening degree of the brake pedal BP, and maintains the brake pressure held in step S110. Is maintained, and the process proceeds to step S112. On the other hand, when the opening degree of the brake pedal BP is 0 (NO in step S111), the brake control unit 300a determines that the driver's foot has been released from the brake pedal BP, and proceeds to step S114.

The brake control unit 300a, then after holding the brake pressure (maintained), and the front wheel drive shaft 28 torque (after the braking force holding torque) signal detected by the torque sensor 42, to get through the torque obtaining section 300a ₁ ( Step S112).

  The brake control unit 300a determines whether or not the torque signal detected by the torque sensor 42 has changed (for example, has changed to a small value). Specifically, the brake control unit 300a compares the post-braking force torque with the vehicle stop state torque stored in a storage unit (not shown). Then, as a result of the comparison, the brake control unit 300a determines whether the torque after holding the braking force is smaller than the vehicle stop state torque (step S113). If the post-braking force holding torque is smaller than the vehicle stop state torque (YES in step S113), the brake control unit 300a determines that the vehicle 1 shifts from the stop state to the movable state, and proceeds to step S107. In addition, when the braking force holding torque is equal to or greater than the vehicle stop state torque (NO in step S113), the brake control unit 300a determines that the vehicle 1 is maintaining the stop state, returns to step S111, and returns to step S111. And the process of step S112 is performed again.

  When the opening degree of the brake pedal BP is 0, the brake control unit 300a determines that the driver's foot has separated from the brake pedal BP, reduces the brake pressure (step S114), and ends the vehicle braking process.

  As described above, the brake control unit 300a controls the brake pressure of the vehicle 1 based on the comparison result obtained by comparing the vehicle stop state torque and the torque detected by the torque sensor 42. Specifically, the brake control unit 300a performs the processes of steps S103 to S105 and steps S107 to S109 shown in FIG. 3 to achieve the vehicle 1 with the minimum brake pressure necessary for the vehicle 1 to maintain the stop state. Can be maintained in a stopped state. At this time, even if the driver accidentally operates the brake pedal BP so as to excessively increase the brake pressure, the brake control unit 300a maintains the minimum brake pressure necessary for the vehicle 1 to maintain the stop state ( Maintenance).

  Therefore, even when the brake mechanism is a mechanism that opens the brake pad with a spring, the brake pad can be prevented from returning due to the strength of the spring due to excessive brake pressure. As a result, it can be reduced that the brake pad is pressed against the brake rotor during traveling.

  Therefore, according to the present embodiment, it is possible to improve the deterioration of fuel consumption while ensuring the safety of the vehicle stopped state.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the above-described embodiments, and various modifications within the scope described in the claims. Needless to say, the modified examples also belong to the technical scope of the present invention.

  In the above embodiment, the brake control unit 300a performs the processes of steps S103 to S105 and steps S107 to S109. However, at least one of the processes of steps S103 to S105 and steps S107 to S109 may be performed. .

  For example, the brake control unit 300a may perform a process of increasing a predetermined amount of brake pressure instead of steps S107 to S109 after performing the processes of steps S103 to S105. As described above, after performing the processes of steps S103 to S105, the brake pressure necessary to maintain the stop state of the vehicle 1 is necessary even if the process of increasing the brake pressure by a method different from steps S107 to S109 is performed. It can prevent becoming larger than the above.

  The brake control unit 300a performs a process of reducing the brake pressure until the output signal of the vehicle speed sensor 40 (or the acceleration sensor) changes, for example, instead of steps S103 to S105, and then performs the processes of steps S107 to S109. May be performed. Thus, after performing the process which reduces brake pressure by the method different from step S103-S105, even if the process of step S107-S109 is performed, the brake pressure required in order to maintain the stop state of the vehicle 1 is required It can prevent becoming larger than the above.

  In the above embodiment, the brake control unit 300a compares the torque detected by the torque sensor 42 with the vehicle stop state torque stored in the storage unit (not shown). It may be determined whether or not a change has occurred.

  Specifically, for example, the brake control unit 300a may determine whether or not the torque signal detected by the torque sensor 42 has changed (for example, has changed to a small value) in step S105. That is, it may be determined whether or not a change has occurred in the torque (torque after braking force reduction) while reducing the brake pressure with reference to the vehicle stop state torque. Note that when a change occurs in the torque after reducing the braking force, the torque after reducing the braking force is smaller than the vehicle stop state torque, and therefore, substantially the same processing as step S105 can be performed. Accordingly, in step S105, the brake control unit 300a returns to step S103 if there is no change in the torque detected by the torque sensor 42, decreases the brake pressure, and if there is a change in the torque detected by the torque sensor 42, the step The process proceeds to S107 and the brake pressure is increased.

  In addition, the brake control unit 300a may determine whether or not the torque signal detected by the torque sensor 42 has changed (for example, has changed to a large value) in step S109. In other words, with reference to the torque immediately before increasing the brake pressure (torque after braking force reduction), it is possible to determine whether or not a change has occurred in the torque (torque after increasing braking force) while increasing the brake pressure. Good. Note that when the torque after the braking force increases, the torque after the braking force increases becomes equal to or greater than the vehicle stop state torque, so that substantially the same processing as step S109 can be performed. Accordingly, in step S109, if there is no change in the torque detected by the torque sensor 42, the brake control unit 300a returns to step S107, increases the brake pressure, and if there is a change in the torque detected by the torque sensor 42, the step The process proceeds to S110 and the brake pressure is maintained.

  Further, the brake control unit 300a may determine whether or not the torque signal detected by the torque sensor 42 has changed (for example, has changed to a small value) in step S113. In other words, with reference to the torque immediately before holding the brake pressure (torque after increasing braking force), it is determined whether the torque (torque after holding braking force) has changed while holding the brake pressure. May be. Note that when a change occurs in the torque after holding the braking force, the torque after holding the braking force becomes smaller than the vehicle stop state torque, and therefore, a process substantially equivalent to step S113 can be performed. Therefore, in step S113, if there is no change in the torque detected by the torque sensor 42, the brake control unit 300a returns to step S111, maintains the brake pressure, and if there is a change in the torque detected by the torque sensor 42, the step The process proceeds to S107 and the brake pressure is increased.

  The present invention can be used for a vehicle braking device and a vehicle braking method for braking a vehicle.

42 Torque sensor (detector)
300a Brake control unit 300a ₁ Torque acquisition unit BP Brake pedal (braking operation member)

Claims (10)

A detector that detects torque of a rotating shaft that transmits the power of a prime mover provided in the vehicle to drive wheels;
A torque acquisition unit that acquires a torque detected by the detection unit as a vehicle stop state torque in a vehicle stop state in which the vehicle is stopped;
A control unit for controlling the braking force applied to the drive wheel based on a comparison result of comparing the vehicle stop state torque and the torque detected by the detection unit after acquiring the vehicle stop state torque;
A vehicle braking device comprising:   The vehicle braking device according to claim 1, wherein the control unit reduces the braking force when there is no change in the torque detected by the detection unit.   The vehicle braking device according to claim 2, wherein the control unit reduces the braking force until the torque detected by the detection unit is smaller than the vehicle stop state torque.   4. The vehicle braking device according to claim 1, wherein the control unit increases the braking force when the torque detected by the detection unit decreases. 5.   The vehicle according to claim 4, wherein the control unit increases the braking force until the torque detected by the detection unit increases when the torque detected by the detection unit becomes smaller than the vehicle stop state torque. Braking device.   4. The vehicle braking device according to claim 1, wherein the control unit retains the braking force when the torque detected by the detection unit increases. 5.   4. The vehicle braking device according to claim 2, wherein the control unit holds the braking force when the braking force becomes a predetermined value or less without changing the torque detected by the detection unit. 5. The vehicle has a braking operation member for a driver to operate the braking force,
8. The control unit according to claim 6, wherein the controller holds the braking force regardless of an operation amount of the braking operation member when the operation amount of the braking operation member is equal to or greater than a predetermined amount in the vehicle stop state. Vehicle braking device.   9. The vehicle braking device according to claim 6, wherein the control unit increases the braking force when the torque detected by the detection unit decreases after holding the braking force. 10. Detecting the torque of the rotating shaft that transmits the power of the prime mover provided in the vehicle to the drive wheels by the detection unit;
Acquiring a torque detected by the detection unit as a vehicle stop state torque in a vehicle stop state in which the vehicle is stopped;
Controlling the braking force applied to the drive wheel based on a comparison result of comparing the vehicle stop state torque and the torque detected by the detection unit after acquiring the vehicle stop state torque;
A vehicle braking method.

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