JPH09324669A - Braking device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a braking device for vehicles for suppressing a output change of an engine at the time of changing a speed at a low speed in a braking device for providing a braking force to an output of the engine. SOLUTION: There is provided braking force generating means for providing a braking force to an output of an engine, speed change instruction means for outputting a speed change instruction to a speed transmission, and suspending means (S12 and S20) for suspending an operation of braking force generating means. This suspending means suspends an operation of braking force generating means irrespective of the presence or absence of a speed change instruction when a speed V is equal to or less than a predetermined automobile speed V1 (S17 and S20).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle braking system, and more particularly to a vehicle braking system that applies a braking force to the output of an engine.

[0002]

[Related Background Art] In a large vehicle such as a truck or a bus, the weight of the vehicle becomes large. Therefore, in addition to an ordinary service brake that applies a braking force to wheels, an on-off valve such as a butterfly valve in the exhaust pipe of the engine. An exhaust brake (exhaust brake) that suppresses the flow of exhaust gas by closing the butterfly valve and thereby gives a braking force to the output of the engine itself to brake the vehicle is adopted. .

By the way, normally, a vehicle is provided with a transmission for performing a gear shift. In such a transmission, a gear is temporarily moved through a neutral state during gear shift. To be achieved. However, in the neutral state, since the output of the engine is not transmitted to the wheels, even if the exhaust brake operates as described above at the time of gear shifting, it does not contribute to the braking at all, and conversely the exhaust efficiency deteriorates. Yes, it causes an engine stall.

Therefore, a device having a structure for temporarily stopping the exhaust brake when a gear shift is performed, particularly when downshifting is disclosed in Japanese Utility Model Laid-Open No. 4-98622.

[0005]

By the way, as disclosed in the above publication, if the exhaust brake is interrupted at the time of shifting and then restarted at the end of the shifting, the braking is suddenly stopped when the exhaust brake works again. Power will increase. In this way, when the exhaust brake suddenly acts, especially when the vehicle is traveling at a low vehicle speed, the engine brake originally tends to be large and the exhaust brake acts. There is a risk of giving a large shock to the vehicle and giving the driver a feeling of strangeness.

The present invention has been made based on the above-mentioned circumstances, and an object of the present invention is, in a braking device that applies a braking force to the output of the engine, to reduce fluctuations in the output of the engine during shifting at low vehicle speeds. An object is to provide a restrained vehicle braking device.

[0007]

In order to achieve the above object, in the invention of claim 1, a braking force generating means for applying a braking force to the output of the engine, and a shift commanding means for outputting a shift command to the transmission are provided. A stop means for stopping the operation of the braking force generating means when the shift command is output during the operation of the braking force generating means, and a vehicle speed detecting means for detecting a vehicle speed. When the vehicle speed detected by the vehicle speed detecting means is equal to or lower than the first predetermined vehicle speed, the operation of the braking force generating means is stopped regardless of the presence or absence of the shift command.

Therefore, normally, when a shift command is output,
The operation of the braking force generating means, for example, the operation of the exhaust brake or the like, is stopped. However, when the vehicle speed is equal to or lower than the first predetermined vehicle speed, the operation by the braking force generating means is stopped regardless of the presence or absence of the shift command. To be done. As a result, at low vehicle speeds, a shock that particularly greatly affects the vehicle when the operation of the braking force generating means is once stopped and then restarted is suitably prevented.

Further, in the invention of claim 2, after the stopping means stops the operation of the braking force generating means, the shift command is not output and the vehicle speed is higher than the first predetermined vehicle speed. When the second predetermined vehicle speed or more is reached, the operation of the braking force generating means is restarted. Therefore, after the operation of the braking force generating means is once stopped, the operation of the braking force generating means is restarted unless the shift command is output and the speed reaches the second predetermined vehicle speed which is higher than the first predetermined vehicle speed. That is, the hysteresis is provided, and it is possible to prevent the activation and resumption of the braking force generation means from being frequently repeated.

Further, the invention of claim 3 is characterized in that the transmission is an automatic transmission. Therefore, in an automatic transmission that shifts gears when the driver is not aware, the operation of the braking force generation means is favorably stopped when the vehicle speed is low, and the braking force generation means is abruptly stopped and restarted. It is possible to prevent the vehicle from being shocked.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows the overall configuration of a drive system of a vehicle (truck, bus, etc.) to which the braking device according to the present invention is applied. Hereinafter, the configuration of the drive system of the vehicle including the braking device for the vehicle will be described with reference to FIG.

Referring to FIG. 1, a diesel engine (hereinafter referred to as engine) 1 is connected to an engine output shaft 2
The engine output shaft 2 is connected to a gear type transmission (hereinafter simply referred to as a transmission) 4 via a clutch device 3.
It is connected to the. As a result, the output of the engine 1 is transmitted to the transmission 4, and the transmission 4 performs a shift. The transmission 4 has seven forward speeds (1 speed) in addition to the reverse speed.
It is an automatic speed change type transmission having a speed range of 7th to 7th speeds and is capable of performing not only automatic speed change but also manual speed change. The clutch device 3 is configured so that, when the transmission 4 is automatically shifted, the clutch device 3 is automatically controlled to be connected or disconnected, which will be described later in detail.

The engine 1 has a fuel injection pump (hereinafter referred to as an injection pump) for supplying fuel to the engine 1.
6 are provided. The injection pump 6 is a device that operates the pump by the output of the engine 1 transmitted via a pump input shaft (not shown) to inject fuel. The injection pump 6 is provided with a control rack (not shown) for adjusting a fuel injection amount, and further provided with a rack position sensor 9 for detecting a rack position (control rack position) RW of the control rack. Have been. In the vicinity of the pump input shaft, an engine rotation sensor 8 for detecting the rotation speed of the pump input shaft and detecting the rotation speed of the output shaft 2 of the engine 1, that is, the engine rotation speed Ne, based on the rotation speed is provided. I have.

The clutch device 3 is an ordinary machine in which the clutch plate 12 is pressed against the flywheel 10 by the pressure spring 11 to be in the connected state, while the clutch plate 12 is separated from the flywheel 10 to be in the disconnected state. The friction clutch can be operated not only manually but also automatically. That is, the air cylinder unit 16 which is interlocked with the clutch pedal 13 and functions as a clutch connecting / disconnecting actuator is connected to the clutch plate 12 via the outer lever 12a. The air cylinder unit 16 is provided with an air tank 34 through an air passage 30 which is an air supply passage.
Is connected. A magnet valve 31 is provided in the air passage 30. Therefore, air is supplied from the air tank 34 through the air passage 30 in response to opening and closing of the magnet valve 31, and the air cylinder unit 16
Operates automatically. As a result, the clutch plate 12 moves, and the connection and disconnection of the clutch are automatically performed.

More specifically, when the air cylinder unit 16 shifts from the non-actuated state to the actuated state, the clutch plate 12 moves in the direction away from the flywheel 10, whereby the clutch device 3 changes from the engaged state to the disengaged state. To do. On the other hand, when the air cylinder unit 16 is in the non-operation state, the clutch plate 12 is brought into pressure contact with the flywheel 10 by the pressure spring 11, and the clutch device 3 is held in the connected state. The automatic connection and disconnection of the clutch is performed in accordance with the automatic transmission of the transmission 4 as described above.

A hydraulic master cylinder 13a is connected to the clutch pedal 13 so as to interlock with the depression operation of the clutch pedal 13. The hydraulic master cylinder 1 is connected to the hydraulic master cylinder 1a.
The oil passage 13b is connected to 3a. The oil passage 13b is connected to the air cylinder unit 16.
Therefore, when the clutch pedal 13 is depressed, hydraulic oil is supplied from the hydraulic master cylinder 13a to the air cylinder unit 16 side via the oil passage 13b, whereby the clutch plate 12 operates via the air cylinder unit 16,
The clutch device 3 can be operated not only automatically but also manually.

The change lever 60 is a select lever of the transmission 4 and has a select pattern as shown in the box in FIG. That is, this change lever 6
0 can move in the select direction and a direction orthogonal to the select direction, and further can move from the position moved in the orthogonal direction to the shift direction parallel to the select direction. Change lever 6
Describing the 0 select pattern, in the select direction, N (neutral) range, R (reverse)
The D (drive) range corresponding to the range and the automatic shift mode is set. The position moved in the direction orthogonal to the select direction, that is, the range in which the change lever 60 can move in the shift direction is the M (manual) range corresponding to the manual shift mode. The shift pattern in the M range is described as follows.
HOLD (hold) set at a position where the change lever 60 is horizontally moved from the D range to the M range.
The UP (shift up) position and the DOWN (shift down) position are set so as to sandwich the position. That is, in the shift direction, the UP position and the D position are sandwiched by the HOLD position which is the neutral position.
The OWN position and the OWN position are arranged in a line, that is, I
A mold shift pattern is constructed.

In such a select pattern and shift pattern, the change lever 60 located in the N range, R range, and D range is held in that position and stopped even if the driver's hand is released after the operation to that position. On the other hand, when the M range is selected and the shift operation is performed from the HOLD position to the UP position or the DOWN position, if the driver's hand is released after the operation,
It automatically returns to the neutral position, that is, the HOLD position, and is held at that position (HOLD position).

The change lever 60 is connected to the ECU 80, and as will be described later, the ECU 80 is connected to a gear shift unit 64 for meshing gears of the transmission 4, that is, for changing the gear position. As a result, when the detection signal of each range and position is supplied to the ECU 80, the gear shift unit 6 is responsive to this signal.
4 is operated so that the gear position of the transmission 4 can be switched according to the selected select range and shift position.

The gear shift unit 64 includes a plurality of solenoid valves (only one of which is shown in FIG. 1) 66 operated by an operation signal from the ECU 80, and a plurality of shift forks (not shown) in the transmission 4. Power cylinder (not shown). These power cylinders of the gear shift unit 64 are connected to the electromagnetic valve 66, the air passage 67,
And is connected to the above-described air passage 30, and thus operates when high-pressure operating air is supplied from the air tank 34. That is, the electromagnetic valve 66 is connected to the ECU 80.
, Each power cylinder operates according to the operation signal, whereby the meshing state of the gear transmission 4 is appropriately changed.

Near the gear shift unit 64 of the transmission 4, a gear position switch 68 as a gear position sensor for detecting each shift stage is attached. From the gear position switch 68, a current gear position signal is sent to the ECU 80. Will be output. The accelerator pedal 70 is provided with an accelerator opening sensor 72. This accelerator opening sensor 72
Outputs the amount of depression of the accelerator pedal 70. A vehicle speed sensor (vehicle speed detecting means) 78 for detecting a vehicle speed V is attached to the output shaft 76 of the transmission 4.

Reference numeral 82 in FIG. 1 denotes an engine control unit provided separately from the ECU 80.
The engine control unit 82 is a device that supplies a signal from the ECU 80 corresponding to information from each sensor and accelerator opening information VA to an electronic governor (not shown) in the injection pump 6. Drive control is performed. That is, the engine control unit 82
When a command signal is supplied from the electronic governor to the electronic governor, the control rack is operated to increase or decrease the fuel, and the increase or decrease of the engine speed Ne is controlled.

Reference numeral 99 in the drawing is a main power switch of an electric system such as the ECU 80 and the engine control unit 82, that is, an ignition key switch, and reference numeral 94 is a buzzer 94 which emits a sound such as an alarm sound. ,
Reference numeral 96 is a display unit that displays various traveling states of the vehicle. Reference numeral 100 in the figure denotes an exhaust manifold of the engine 1. An exhaust pipe 102 that guides exhaust gas extends from the exhaust manifold 100. Then, in the exhaust pipe 102, a butterfly valve 1 that functions as an exhaust brake (braking force generating means).
04 is installed. In addition, this butterfly valve 1
04 is normally in the valve open state, and the exhaust pipe 102
Exhaust gas is made to flow well inside. And
Reference numeral 106 is an actuator for opening and closing the butterfly valve 104.

Reference numeral 108 in the figure denotes the actuator 1 described above.
It is an exhaust brake switch (SW) for driving 06 to operate the exhaust brake, and when the exhaust brake SW 108 is turned on,
The actuator 106 is driven via the ECU 80 to close the butterfly valve 104, and the exhaust brake operates.

The ECU 80 is a microcomputer (C
PU), a memory, and an interface as an input / output signal processing circuit. On the input side of the ECU 80, the engine rotation sensor 8, the rack position sensor 9, the clutch step sensor 15, the clutch stroke sensor 17, the clutch touch sensor 18, the clutch rotation sensor 22, the gear position switch 68, and the accelerator opening sensor 7 are provided on the input side.
2. A vehicle speed sensor 78, an ignition key switch 99, an exhaust brake SW 108, etc. are connected to each other, and information from these sensors etc. is input.

On the other hand, on the output side of the ECU 80, the above-mentioned magnet valve 31, electromagnetic valve 66, engine control unit 82, buzzer 94, display unit 9 are provided.
6 and the actuator 106 are connected. The memory of the ECU 80 is composed of a read-only ROM in which a flowchart (not shown) is written as a program or data and a writable RAM.

For example, in the ROM, when the selected position is in the D range, a shift map for determining the target shift speed on the basis of the vehicle speed V, the accelerator opening VA and the engine speed Ne (see FIG. (Not shown) is stored.
Therefore, when the selected position is in the D range, an appropriate shift map is first selected, and the target shift speed is determined from this shift map based on the vehicle speed V, the accelerator opening VA or the engine speed Ne. Then, the ECU 80
A shift signal corresponding to the target shift speed is given to each solenoid valve 66 of the gear shift unit 64 to adjust the gear to the target shift speed. As a result, automatic shift control is performed.

In this way, when the gear of the transmission 4 is switched to the target shift stage and the shift is completed, the gear position signal is output from the gear position switch 68. As a result, it is determined whether or not the gears are reliably switched with respect to the shift signal, that is, whether or not the meshing is in a normal state. When the target shift speed is determined as described above, the ECU 80 supplies a shift signal corresponding to the target shift speed to each electromagnetic valve 66 of the gear shift unit 64 and also supplies a predetermined drive signal to the magnet valve 31. . As a result, the air cylinder unit 16 is actuated at the same time as the shift is started and the clutch plate 12 is moved to the flywheel 1
The clutch device 3 is disengaged from 0. Then, when the shift is substantially achieved, the magnet valve 31 is controlled well, the clutch plate 12 is gradually pressed against the flywheel 10, and the clutch device 3 is reengaged.

By the way, referring to FIG. 2, there is shown a flowchart of the control routine for the exhaust brake, and the control procedure for the exhaust brake will be described below with reference to FIG. First, when the ignition key switch 99 is turned on, the control routine is initialized, and at the same time, all the flags in the control routine are reset to the value 0. That is, the flag Fex described later is also reset to the value 0.

In step S10, it is determined whether or not the exhaust brake SW 108 has been turned on. If the determination result is false (No), the exhaust brake SW108
If is not turned on and is turned off, then in step S14
Proceed to. In step S14, it is determined whether or not the flag Fex is 0. This flag Fex is a control variable that is set to a value of 1 when the determination result of the vehicle speed determination in step S17 described later is true and the exhaust brake is deactivated based on this vehicle speed determination. If the determination result is false and the flag Fex is not 0, the flag Fex is set to 0 in step S15, and the process proceeds to step S20.

In step S20, the actuator 10
The signal supply to 6 is cut off so that the exhaust brake is not activated. On the other hand, the determination result of step S10 is true (Yes), and the exhaust brake SW
If it is determined that 108 is turned on, then the process proceeds to step S11. In step S11, the accelerator opening VA is used to determine whether or not the driver has an intention to accelerate.
Is 0 or not. When the determination result is false and the accelerator opening VA is not 0, it can be determined that the driver wants acceleration, and in this case, the process proceeds to step S14 described above. Then, it is determined whether or not the flag Fex has a value of 0. If the discrimination result is false and the flag Fex is not a value of 0, the flag Fex is set to a value of 0 in step S15, and then the process proceeds to step S20. And, again, the exhaust brake is deactivated.

On the other hand, if the determination result of step S11 is true,
When the accelerator opening VA is 0, it can be determined that the driver does not want to accelerate, and in this case, the process proceeds to step S12. In step S12, it is determined whether gear shifting is in progress. Specifically, it is determined whether an operation signal (shift command) is supplied from the ECU 80 toward the air cylinder unit 16, that is, whether a shift command is output and shift control is started. If the determination result is true and the shift control is started and it is determined that the shift is in progress, the process proceeds to step S20 through steps S14 and S15, and the exhaust brake is also inactivated (OFF) (see FIG. 3). , Do not activate the exhaust brake (stop means). As a result, at the time of gear shifting, the exhaust brake does not operate at all, and engine stall or the like is prevented. The state where the exhaust brake is not operated (OFF) is continued until the determination result in step S12 is false, that is, until the clutch connection is completed and the shift control is completed (see FIG. 3). . On the other hand, if the determination result is false and it is determined that gear shifting is not in progress, then the process proceeds to step S16.

In step S16, it is determined whether or not the flag Fex is 0. That is, step S17 described below.
Based on the result of the vehicle speed determination, it is determined whether or not the exhaust brake is deactivated and the flag Fex is not set to the value 1. When the determination result is true and the flag Fex is 0, that is, when the exhaust brake is not inactivated based on the result of the vehicle speed determination, the process proceeds to step S17.

In step S17, the vehicle speed is determined. Here, it is determined whether or not the vehicle speed V detected by the vehicle speed sensor 78 is equal to or lower than a first predetermined vehicle speed V1 (for example, 15 km / h). The determination result is true, and the vehicle speed V is the predetermined vehicle speed V1.
When it is determined that the speed is 15 km / h or less (for example, 15 km / h) or less, the value Fex is set to 1 and stored in the next step S18, in which the exhaust brake is not operated based on the vehicle speed determination. Then, the process proceeds to step S20, and in this case as well, the exhaust brake is deactivated (stopping means). As a result, the vehicle speed V becomes the predetermined vehicle speed V1.
When the speed is 15 km / h or less (for example, 15 km / h) or less, a large shock that occurs when the operation of the exhaust brake is resumed after the operation of the exhaust brake is prevented regardless of the presence or absence of gear shift.

On the other hand, the determination result of step S17 is false,
When it is determined that the vehicle speed V is higher than the predetermined vehicle speed V1 (for example, 15 km / h), the process proceeds to step S28, and the exhaust brake is activated. By the way, when the determination result of the above step S16 is false and the flag Fex has the value 1, that is, the exhaust brake SW108 is turned on (step S10), the accelerator opening degree VA is also set to the value 0 (step S11), and the shift is performed. Although it is not in the middle (step S12), if the exhaust brake is deactivated because the vehicle speed V is equal to or lower than the predetermined vehicle speed V1 (for example, 15 km / h) in step S17, the following is performed. To step S24.

In step S24, it is determined whether or not the vehicle speed V is at least the second predetermined vehicle speed V2 (for example, 19 km / h). When the vehicle is accelerating, the determination result is true, and when it is determined that the vehicle speed V has reached the predetermined vehicle speed V2 (for example, 19 km / h) or more, the state where the exhaust brake is not activated is released in step S26. Flag F
Reset ex to a value of 0. Then, the above step S
Proceed to 28 to return the exhaust brake to the operating state,
Reactivate the exhaust brake.

On the other hand, the determination result of step S24 is false,
When it is determined that the vehicle speed V has not reached the predetermined vehicle speed V2 (for example, 19 km / h), the process proceeds to step S20 described above, and the exhaust brake remains inoperative. That is, in step S24, the vehicle speed V is the above-mentioned step S1.
When the judgment threshold value V2 (for example, 19 km / h) larger than the judgment threshold value V1 (for example, 15 km / h) used for the judgment of No. 7 is set, the exhaust brake, which was once deactivated, is reactivated. I have to. In other words, here
In order to prevent frequent activation and non-activation of the exhaust brake, a hysteresis for operating (on) and stopping (off) the exhaust brake is provided as shown in FIG.

As described above in detail, in the braking apparatus of the present invention, the exhaust brake is basically deactivated when the shift control is performed. In particular, the vehicle speed V is the predetermined vehicle speed. V1 (for example, 15km / h)
When it becomes smaller than the following value, the exhaust brake is deactivated regardless of the presence or absence of gear shift control. In this way, by disabling the exhaust brake at low vehicle speeds, normally, when the exhaust brake is stopped and restarted when gear shifting is performed at low vehicle speed, a suddenly large braking force is restarted. Tends to cause a large shock to the vehicle,
Such a shock is preferably prevented in advance. As a result, the traveling feeling is improved particularly when the vehicle is traveling at a low vehicle speed with the exhaust brake in the operating state.

By deactivating the exhaust brake at a low vehicle speed in this way, the engine speed Ne
When the vehicle speed is small and the engine stalls easily, it is possible to prevent the engine stall from occurring due to sudden braking, and it is also possible to facilitate and stabilize the fuel injection control at the low vehicle speed. In the above embodiment, the exhaust brake is taken as the braking force generating means, but the invention is not limited to this, and the same applies to the braking force generating means such as the compression pressure release type engine auxiliary brake and the flywheel retarder. The effect is obtained.

Further, in the above embodiment, an example in which the transmission 4 capable of automatic shifting is used has been described, but the same effect can be obtained by using a manual transmission only by manual operation.

[0041]

As described above in detail, according to the vehicle braking device of the first aspect of the present invention, the braking force generating means for applying the braking force to the output of the engine and the shift command to the transmission are output. Gear shift command means, a stop means for stopping the operation of the braking force generation means when the shift command is output during the operation of the braking force generation means, and a vehicle speed detection means for detecting the vehicle speed. When the vehicle speed detected by the vehicle speed detecting means is equal to or lower than the first predetermined vehicle speed, the operation of the braking force generating means is stopped regardless of the presence or absence of the gear change command. Actuation of power generation means,
For example, the operation of the exhaust brake or the like is stopped, but when the vehicle speed is equal to or lower than the first predetermined vehicle speed,
The operation by the braking force generating means can be stopped regardless of the presence or absence of the shift command. Therefore, at low vehicle speed, it is possible to preferably prevent a shock that particularly greatly affects the vehicle when the operation of the braking force generating means is once stopped and then restarted, and the traveling feeling can be improved. .

According to another aspect of the vehicle braking device of the present invention, the stopping means, after stopping the operation of the braking force generating means,
When the speed change command is not output and the vehicle speed becomes equal to or higher than the second predetermined vehicle speed which is higher than the first predetermined vehicle speed, the operation of the braking force generating means is restarted. After the operation of the generating means is stopped,
It is possible to prevent the operation of the braking force generating means from being restarted unless the vehicle speed reaches the second predetermined vehicle speed which is higher than the first predetermined vehicle speed, so that the operation and the restart of the braking force generating means are not frequently repeated.

Further, according to the vehicle braking device of the third aspect, since the transmission is an automatic transmission, the automatic transmission in which gear shifting is performed when the driver is not aware of the transmission is controlled when the vehicle speed is low. The operation of the power generation means can be favorably stopped, and the braking force generation means that is abruptly generated can be stopped.
It is possible to suitably prevent a shock of the vehicle due to the restart and prevent the driver from feeling uncomfortable.

[Brief description of drawings]

FIG. 1 is a diagram showing an overall configuration of a drive system of a vehicle to which a braking device according to the present invention is applied.

FIG. 2 is a flowchart showing an exhaust brake control routine.

FIG. 3 is a diagram showing changes over time in a clutch stroke SCL, a shift speed and an exhaust brake during a shift.

FIG. 4 is a diagram showing a relationship between the operation of an exhaust brake and a vehicle speed V.

[Explanation of symbols]

 1 Diesel engine 4 Transmission 16 Air cylinder unit 60 Change lever 78 Vehicle speed sensor (vehicle speed detecting means) 80 Electronic control unit (ECU) 104 Butterfly valve (braking force generating means) 106 Actuator (braking force generating means) 108 Exhaust brake SW ( Braking force generation means)

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical indication location F02D 29/00 F02D 29/00 C 45/00 312 45/00 312N (72) Inventor Takao Nishina Ota-ku, Tokyo Shimomaruko 4-21-1 Mitsubishi Motors Engineering Co., Ltd. (72) Inventor appearance Masakatsu Shimomaruko 4-21-1 Mitsubishi Motors Engineering Co., Ltd.

Claims (3)

[Claims] 1. A braking force generating means for applying a braking force to an output of an engine, a gear shift command means for outputting a gear shift command to a transmission, and a gear shift command output while the braking force generating means is operating, The stopping means for stopping the operation of the braking force generating means and the vehicle speed detecting means for detecting the vehicle speed are provided, and the stopping means, when the vehicle speed detected by the vehicle speed detecting means is equal to or lower than a first predetermined vehicle speed, A braking device for a vehicle, characterized in that the operation of the braking force generating means is stopped regardless of the presence or absence of a shift command. 2. The stopping means, after stopping the operation of the braking force generating means, has not output the shift command and has a vehicle speed equal to or higher than a second predetermined vehicle speed which is higher than the first predetermined vehicle speed. 2. The braking device for a vehicle according to claim 1, wherein the operation of the braking force generating means is restarted when the braking force is reduced. 3. The vehicle braking device according to claim 1, wherein the transmission is an automatic transmission.