JP4233667B2 - Braking force control device for vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a vehicle including an automatic transmission that transmits driving force of an engine to driving wheels, and more particularly to an apparatus for controlling braking force immediately before the vehicle stops.
[0002]
[Prior art]
  FIG. 7 schematically shows changes in braking force and driving force when the driver stops the vehicle while stepping on the brake pedal with a constant depression force. The solid line is the manual braking force generated when the driver depresses the brake pedal, and maintains a substantially constant magnitude, while the broken line indicates the engine braking force andAutomatic transmissionThe creep force changes with time (that is, as the vehicle speed decreases). Specifically, as the vehicle speed decreases, the engine braking force gradually decreases, and after the engine braking force becomes zero at point P, the creep force that is the driving force gradually increases. As a result, the total braking force, which is the sum of the manual braking force and the engine braking force (or creep force), decreases immediately before the vehicle stops, increasing the braking distance and causing the driver to feel uncomfortable. appear.
[0003]
  By the way, various devices for automatically controlling the magnitude of the braking force according to the driving state of the vehicle have been proposed. For example, anti-lock brake control that reduces the braking force acting on the wheel to prevent the wheel from locking due to braking, and braking force applied to the wheel to prevent excessive slip of the wheel on a low friction coefficient road surface Japanese Patent Publication No. 5-65388 discloses a braking control device capable of performing traction control. There is also an active booster that assists the driver's brake operation and increases the braking force by electrically controlling the operation of the negative pressure booster that boosts and transmits the pedaling force applied by the driver to the master cylinder. This is known from JP-A-9-30402.
[0004]
[Problems to be solved by the invention]
  As mentioned above, the engine braking force decreases immediately before the vehicle stops andAutomatic transmissionSince the total braking force decreases due to the generation of creep force, it is necessary for the driver to step on the brake pedal to stop the vehicle reliably. However, every time the vehicle is stopped, the brake pedal must be stepped on. That is troublesome.
[0005]
  The present invention has been made in view of the above-described circumstances, and an object thereof is to automatically compensate for a decrease in braking force generated immediately before the vehicle stops by using an automatic braking means.
[0006]
[Means for Solving the Problems]
  In order to achieve the above object, according to the first aspect of the present invention, in a vehicle equipped with an automatic transmission that transmits the driving force of an engine to driving wheels, the driving is performed without depending on a driver's braking operation. Automatic braking means that can brake the wheel and the vehicle, Total braking force decreases due to decrease of engine braking force and generation of creep force of automatic transmissionStop straightFrontThe state immediately before stop detecting means for detecting that the vehicle is in a state and the state detecting means immediately before stopAboveStop straightFrontstateButdetectionIsWhen the automatic braking means is activatedTo compensate for the decrease in engine braking force and the generation of creep forceThere is proposed a braking force control device for a vehicle, comprising braking control means for automatically braking the driving wheel.
[0007]
  According to the above configuration,Vehicle, Total braking force decreases due to decrease of engine braking force and generation of creep force of automatic transmissionStop straightFrontBeing in a stateHowever, by the state detection means immediately before stoppingdetectionIsThen, the braking control means activates the automatic braking means.To compensate for engine braking force reduction and creep force generationSince the drive wheels are automatically braked, the engine braking force decreases and creeps just before the vehicle stops.ForceIt is compensated by the generation of the braking force by the braking control means, and it is possible to prevent an increase in the braking distance and eliminate the driver's uncomfortable feeling without requiring an additional stepping on the brake pedal.
[0008]
  According to a second aspect of the present invention, in addition to the configuration of the first aspect, the state immediately before stop detecting means is in a state immediately before the stop on condition that the rotational speed of the engine has decreased to a predetermined rotational speed. A braking force control apparatus for a vehicle, characterized in that is detected.
[0009]
  According to the above configuration, the state immediately before the stop can be detected from the decrease in the engine speed.
[0010]
  According to a third aspect of the invention, in addition to the configuration of the first aspect, the state immediately before stop detecting means that the vehicle speed has decreased to a predetermined vehicle speed set according to the shift position. A braking force control device for a vehicle is proposed in which the condition immediately before the stop is detected as a condition.
[0011]
  According to the above configuration, the state immediately before stopping can be detected from the decrease in the vehicle speed.
[0012]
  According to the invention described in claim 4, in addition to the configuration of claim 1, the engine stops the fuel supply during the engine brake operation and restarts the fuel supply immediately before the vehicle stops. A braking force control apparatus for a vehicle is proposed, wherein the state immediately before stop detecting means detects the state immediately before stop on condition that the fuel supply is resumed.
[0013]
  According to the above configuration, since the magnitude of the engine braking force and the magnitude of the creep force depend on the timing of restarting the fuel supply, automatic braking is started at an appropriate timing according to the actual fluctuation of the braking force. can do.
[0014]
  According to the fifth aspect of the present invention, in addition to the structure of any one of the first to fourth aspects, the braking force generated by the automatic braking means is the engine braking force at the start of braking by the automatic braking means. And a braking force control device for a vehicle, which is set based on a deviation from a creep force when the vehicle is stopped.
[0015]
  According to the above configuration, it is possible to accurately compensate for the decrease in braking force immediately before the vehicle stops, avoiding an increase in braking distance without the driver depressing the brake pedal, and making the driver feel uncomfortable. Can be resolved.
[0016]
  According to the sixth aspect of the present invention, in addition to any one of the first to fourth aspects, the rising gradient of the braking force generated by the automatic braking means is the pedaling force of the driver's braking operation. A braking force control device for a vehicle is proposed, characterized in that the larger the value is, the larger the value is.
[0017]
  According to the above configuration, the vehicle can be correctly stopped at the stop position predicted by the driver without increasing the brake pedal immediately before stopping.
[0018]
  According to a seventh aspect of the present invention, in addition to any one of the first to sixth aspects, the automatic braking by the automatic braking means ends when the vehicle stops. A braking force control device is proposed.
[0019]
  According to the above configuration, it is not necessary to perform automatic braking, and at the same time, automatic braking can be terminated to save energy.
[0020]
  According to an eighth aspect of the present invention, in addition to the configuration of any one of the first to sixth aspects, the automatic braking by the automatic braking means is terminated when the driver's braking operation is terminated. A braking force control apparatus for a vehicle characterized by the above is proposed.
[0021]
  According to the above configuration, automatic braking can be promptly terminated when the driver's intention to decelerate is lost, and automatic braking that is not desired by the driver can be prevented. Moreover, even after the vehicle has stopped, the automatic braking will not end unless the driver releases the brake pedal, thus avoiding an unexpected decrease in the braking force of the driver after the vehicle is stopped, and the driver feels uncomfortable. It can be prevented from receiving.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, embodiments of the present invention will be described based on examples of the present invention shown in the accompanying drawings.
[0023]
  1 to 5 show a first embodiment of the present invention. FIG. 1 is an overall configuration diagram of a vehicle equipped with a braking force control device, FIG. 2 is an explanatory diagram showing the structure of a braking system, and FIG. 4 is a block diagram showing the circuit configuration of the control unit, FIG. 4 is a flowchart for explaining the action, and FIG. 5 is a time chart for explaining the action.
[0024]
  As shown in FIGS. 1 and 2, the four-wheeled vehicle V equipped with the braking force control device of the present invention has left and right front wheels W as driving wheels to which the driving force of the engine E is transmitted via an automatic transmission T._FL, W_FRLeft and right rear wheels W as driven wheels that rotate as the vehicle V travels_RL, W_RRWith. A brake pedal 1 operated by a driver is connected to a master cylinder 3 via an electronically controlled negative pressure booster 2 constituting the automatic braking means of the present invention. The electronically controlled negative pressure booster 2 mechanically boosts the depressing force of the brake pedal 1 to operate the master cylinder 3, and at the time of automatic braking, the braking command signal from the electronic control unit U is not used regardless of the operation of the brake pedal 1. Thus, the master cylinder 3 is operated. When a pedaling force is input to the brake pedal 1 and a braking command signal is input from the electronic control unit U, the electronically controlled negative pressure booster 2 outputs the brake hydraulic pressure in accordance with whichever is larger. The input rod of the electronically controlled negative pressure booster 2 is connected to the brake pedal 1 through a lost motion mechanism, and the electronically controlled negative pressure booster 2 is actuated by a signal from the electronic control unit U so that the input rod is moved forward. The brake pedal 1 remains in the initial position even when moved to.
[0025]
  The pair of output ports 8 and 9 of the master cylinder 3 are connected to the front wheels W via the hydraulic control device 4._FL, W_FRAnd rear wheel W_RL, W_RRBrake caliper 5_FL, 5_FR, 5_RL, 5_RRConnected to. The hydraulic control device 4 has four brake calipers 5_FL, 5_FR, 5_RL, 5_RRCorresponding to the four pressure regulators 6... Are connected to the electronic control unit U, and each of the pressure regulators 6._FL, W_FRAnd rear wheel W_RL, W_RRBrake caliper 5_FL, 5_FR, 5_RL, 5_RRThe operation of each is controlled individually. Accordingly, each brake caliper 5 is controlled by the pressure regulator 6._FL, 5_FR, 5_RL, 5_RRIf the brake hydraulic pressure transmitted to the vehicle is controlled independently, anti-lock brake control that suppresses wheel lock during braking and traction control that suppresses excessive slip of the wheel when starting on a low friction coefficient road surface can be performed. it can.
[0026]
  The electronic control unit U includes a shift position sensor S that detects a shift position commanded by the shift lever 10.₁ And front wheel W_FL, W_FRAnd rear wheel W_RL, W_RRWheel speed sensor S for detecting the rotation speed of each₂ ... and brake switch S for detecting the operation of the brake pedal 1_Three And an engine speed sensor S for detecting the engine speed_Four And the electronic control unit U is connected to the shift position sensor S.₁ , Wheel speed sensor S₂ ..., brake switch S_Three And engine speed sensor S_Four The braking force immediately before the vehicle V is stopped is increased by controlling the operation of the electronically controlled negative pressure booster 2 based on the signal from. Shift position sensor S₁ Is used to display the shift position on the instrument panel, and the wheel speed sensor S₂ ... is used for anti-lock brake devices and traction control devices, and brake switch S_Three Is used to turn on the brake lamp, and the engine speed sensor S_Four Can be used for various engine controls.
[0027]
  As shown in FIG. 3, the electronic control unit U includes a state immediately before stop detection means M1 and a braking control means M2. The state detection means M1 immediately before stopping is a shift position sensor S.₁ , Wheel speed sensor S₂ ..., brake switch S_Three And engine speed sensor S_Four The vehicle V is stoppedFrontWhether it is in a state is detected. Further, the braking control means M2 is operated by the state detection means M1 just before stopping.WhatVehicle V is, Total braking force decreases due to decrease of engine braking force and generation of creep force of automatic transmission TStop straightFrontWhen it is detected that the vehicle is in a state, the operation of the electronically controlled negative pressure booster 2 is controlled to_FL, W_FRAnd rear wheel W_RL, W_RRIs automatically braked, and the vehicle V is stopped without extending the braking distance and without causing the driver to feel uncomfortable.
[0028]
  Next, the operation of the embodiment of the present invention will be described based on the flowchart of FIG.
[0029]
  First, in step S11, the brake switch S_Three It is confirmed that the driver is stepping on the brake pedal 1 on the basis of a signal from the shift position sensor S in step S12.₁ When it is confirmed that the shift position is in a travel position other than the “N” position based on the signal from, the vehicle V is stopped directly in step S13.FrontIt is determined whether or not it is in a state (that is, the timing for starting automatic braking).
[0030]
  It should be noted that when the shift position is the “N” position in step S12, the reason for not proceeding to step S13 is that when the shift position is the “N” position, neither the engine braking force nor the creep force acts, and the braking force is This is because the brake force is generated only by the brake operation, so that the braking force does not decrease immediately before the stop.
[0031]
  There are several methods for determining the timing of starting automatic braking, but basically the engine speed sensor S_Four When the engine speed detected in step 1 decreases to a preset threshold value, the vehicle VFrontThe automatic braking is started by determining that the state has been reached. Besides this, the wheel speed sensor S₂ It is possible to start automatic braking when the vehicle speed detected in... Falls to a preset threshold value. In this case, the shift position sensor S₁ It is necessary to change the threshold value of the vehicle speed according to the shift position detected in (1). This is because, for example, when the engine braking force is applied at the “second speed fixed position” and when the engine braking force is applied at the “third speed fixed position”, the second speed gear stage and the third speed gear stage. This is because the correspondence between the vehicle speed and the engine speed is different according to the reduction ratio.
[0032]
  Also, in the engine E equipped with the fuel injection device, fuel cut is performed while the engine brake is operating, and the vehicle V is stopped directly.FrontIn order to prevent engine stall, the fuel cut is stopped and the fuel supply is resumed. However, the timing for resuming the fuel supply can be used as the timing for starting the automatic braking. According to this method, the magnitude of the engine braking force and the magnitude of the creep force depend on the timing at which fuel supply is resumed, so automatic braking is started at an appropriate timing in accordance with the actual braking force fluctuation. can do.
[0033]
  In determining the timing for starting automatic braking, more detailed control can be performed if the warm-up state and load state of the engine E (the load of the air conditioner and the power generation load) are taken into consideration. This is because the idle speed of the engine E changes depending on the warm-up state and the load state, and the engine braking force and creep force increase or decrease accordingly.
[0034]
  Thus, when the timing for starting automatic braking is determined in step S13, in step S14, the electronic control unit U operates the electronically controlled negative pressure booster 2 to increase the braking force. That is, the brake hydraulic pressure generated by the master cylinder 3 due to the operation of the electronically controlled negative pressure booster 2 is set to be larger than the brake hydraulic pressure generated when the driver steps on the brake pedal 1, and therefore the electronically controlled negative pressure booster 2 is set. As the pressure booster 2 operates, the braking force increases.
[0035]
  Next, details of the automatic braking immediately before the stop of the vehicle V will be described based on the time chart of FIG.
[0036]
  Time t₀ When the driver depresses the brake pedal 1, the brake hydraulic pressure that generates the braking force rises and at the same time the fuel cut is executed, and the vehicle speed starts to decrease due to the manual braking force and the engine braking force. At this time, the magnitude of the braking force varies depending on the magnitude of the depression force of the brake pedal 1, and the rate of decrease in vehicle speed also changes. The figure shows a case where the pedaling force is large (dashed line), a case where the pedaling force is middle (dashed line), and a case where the pedaling force is small (solid line).
[0037]
  For example, when the pedaling force indicated by the solid line is small, the time t_L The vehicle speed (or engine speed) is₀ When the fuel pressure is lowered, the fuel cut is interrupted and the fuel supply is restarted, and automatic braking is started by operating the electronically controlled negative pressure booster 2 in response to a command from the electronic control unit U. The magnitude of the braking force generated by automatic braking is determined when fuel supply is resumed (time t_L ) And a creep force F when the vehicle V stops. Further, the rising gradient of the braking force by automatic braking is determined as follows. First, the time t when the vehicle speed becomes zero from the rate of decrease in the vehicle speed due to the engine braking force t_L0Predict. And time t_LAt the time t when the vehicle V stops due to the braking force generated by the automatic braking_L0The rising gradient of the braking force is set so that the deviation F is reached.
[0038]
  As described above, the case where the pedal effort of the brake pedal 1 is small has been described. However, since the vehicle speed rapidly decreases as the pedal effort increases, the fuel cut is interrupted and the fuel supply is resumed at time t._M , T_H Is shifted to the faster side as the pedal effort increases, and time t when the vehicle speed becomes zero_M0, T_H0Also shifts to the faster side as the pedal effort increases. Period t during which automatic braking is executed_L ~ T_L0, T_M ~ T_M0, T_H ~ T_H0Is shortened as the pedal effort of the brake pedal 1 is increased, the greater the pedal effort, the greater the rising slope of the braking force by automatic braking.
[0039]
  As described above, the magnitude of the braking force generated by the automatic braking is set as the deviation F between the engine braking force at the start of automatic braking and the creep force when the vehicle V stops. A decrease in braking force can be accurately compensated, and an increase in braking distance can be avoided without the driver depressing the brake pedal 1, and a driver's uncomfortable feeling can be eliminated. In addition, since the rising gradient of the braking force by the automatic braking increases as the driver depresses the brake pedal 1, the stop position predicted by the driver can be obtained without increasing the brake pedal 1 immediately before stopping. The vehicle V can be stopped correctly.
[0040]
  Returning to the flowchart of FIG. 4, when automatic braking is executed in step S14, the termination condition of automatic braking is determined in step S15. There are several methods for determining the timing for ending automatic braking. When the vehicle V stops, when the driver releases his foot from the brake pedal 1, or when the driver operates the shift lever 10, the shift position is reached. One of the times when the position is returned to the “N” position is set as the timing. Thus, when any of the above termination conditions is established, the automatic braking is terminated by stopping the operation of the electronically controlled negative pressure booster 2 in response to a command from the electronic control unit U in step S16.
[0041]
  As described above, by terminating the automatic braking when the vehicle V stops, it is not necessary to perform the automatic braking, and at the same time, the automatic braking can be terminated to save energy.
[0042]
  Further, by terminating the automatic braking when the driver releases the brake pedal 1, the automatic braking can be quickly terminated when the driver's willingness to decelerate is lost. Can be prevented. In addition, even after the vehicle V stops, the automatic braking does not end unless the driver releases his foot from the brake pedal 1, so that an unexpected decrease in the braking force of the driver after the vehicle V is stopped can be avoided. Can be prevented from feeling uncomfortable.
[0043]
  Further, by stopping the automatic braking when the driver returns the shift lever 10 to the “N” position, it is possible to prevent unnecessary automatic braking from being performed when the engine braking force and the creep force are no longer generated. Can do.
[0044]
  Next, another embodiment of the braking system will be described with reference to FIG.
[0045]
  In this embodiment, the anti-lock brake device is used for automatic braking immediately before the stop of the vehicle V. When the automatic braking is started, the electronically controlled negative pressure booster 2 is operated by the electronic control unit U and the master cylinder 3 is maximized. The brake hydraulic pressure is adjusted by the hydraulic control device 4 to generate the brake caliper 5._FL, 5_FR, 5_RL, 5_RRIs transmitted to.
[0046]
  The master cylinder 3 has two output ports 8 and 9, and one output port 8 is connected to the right front wheel W via the hydraulic control device 4._FRAnd left rear wheel W_RLThe brake caliper 5_FR, 5_RLThe other output port 9 is connected to the left front wheel W via the hydraulic control device 4._FLAnd right rear wheel W_RRThe brake caliper 5_FL, 5_RRConnected to. Figure6The right front wheel W is connected to one output port 8_FRAnd left rear wheel W_RLThe brake caliper 5_FR, 5_RLAlthough only the hydraulic control device 4 connected to is shown, the other output port 9 is connected to the left front wheel W._FLAnd right rear wheel W_RRThe brake caliper 5_FL, 5_RRThe hydraulic control device 4 connected to is also the same structure. The right front wheel W_FRAnd left rear wheel W_RLThe structure of the hydraulic control device 4 will be described.
[0047]
  Oil passage L extending from the output port 8 of the master cylinder 3₁ Oil passage L that branches off from₂ , L_Three Are brake calipers 5 through first switching valves 21 and 22 each consisting of a solenoid valve._FR, 5_RLConnected to. Oil path L on the downstream side of the first switching valves 21 and 22₂ , L_Three A pair of oil passages L branching from_Four , L_Five Are connected to the reservoir 25 via second switching valves 23 and 24 each consisting of a solenoid valve, and the reservoir 25 and the oil passage L₁ Oil path L connecting the₆ Is provided with a hydraulic pump 26. The first switching valves 21 and 22 and the second switching valves 23 and 24 are connected to and controlled by the electronic control unit U.
[0048]
  When manual braking is performed, the first switching valves 21 and 22 and the second switching valves 23 and 23 are all in the non-excited state shown in the figure, and the output port 8 of the master cylinder 3 is connected to the right front wheel W._FRThe brake caliper 5_FRAnd left rear wheel W_RLThe brake caliper 5_RLThe brake hydraulic pressure output from the master cylinder 3 when the brake pedal 1 is operated is directly connected to the brake caliper 5._FR, 5_RLIs transmitted to.
[0049]
  During the anti-lock brake control, the brake switch caliper 5 is opened by exciting the second switching valves 23 and 24 while the first switching valves 21 and 22 are excited and closed._FR, 5_RLThe brake hydraulic pressure transmitted to the brake caliper 5 is released to the reservoir 25 and depressurized. From this state, the second switching valves 23 and 24 are de-energized to close the brake caliper 5._FR, 5_RLThe brake hydraulic pressure transmitted to is maintained. Then, by opening the first switching valves 21 and 22 with the first switching valves 21 and 22 being de-energized from this state, the master cylinder 3 is moved to the brake caliper 5._FR, 5_RLTo increase the brake hydraulic pressure. The oil accumulated in the reservoir 18 is returned to the master cylinder 3 by the hydraulic pump 26.
[0050]
  In this way, the first switching valves 21 and 22 and the second switching valves 23 and 24 are controlled to open and close, and the brake caliper 5_FR, 5_RLBy repeatedly reducing, maintaining and increasing the brake hydraulic pressure transmitted to the right front wheel W_FROr left rear wheel W_RLThe braking force can be controlled to an arbitrary magnitude and independently to exhibit the antilock brake function. The left front wheel W_FLAnd right rear wheel W_RRSimilarly, the braking force can be controlled to an arbitrary magnitude and independently.
[0051]
  At the time of automatic braking just before the stop of the vehicle V, the electronic control negative pressure booster 2 is actuated by a command from the electronic control unit U and the master cylinder 3 generates the maximum brake hydraulic pressure. Brake caliper 5 by PWM control of opening_FR, 5_RLIt is possible to generate a braking force by transmitting a brake hydraulic pressure of an arbitrary size.
[0052]
  Although the embodiments of the present invention have been described above, various design changes can be made without departing from the scope of the present invention.
[0053]
  For example, in the braking system shown in FIG. 6, a normal negative pressure booster can be used instead of the electronically controlled negative pressure booster 2, and automatic braking can be performed using the brake hydraulic pressure generated by the hydraulic pump 26 during automatic braking. In this case, a normally open third switching valve that is energized and closed during automatic braking is connected to the oil passage L so that the hydraulic pressure generated by the hydraulic pump 26 does not escape to the master cylinder 3 side.₁ It is necessary to add to. In this case, the hydraulic control device 4 including the hydraulic pump 26 constitutes the automatic braking means of the present invention.
[0054]
【The invention's effect】
  As described above, according to the first aspect of the invention, the state detection means immediately before stopping is used.WhatVehicle, Total braking force decreases due to decrease of engine braking force and generation of creep force of automatic transmissionStop straightFrontBeing in a stateButdetectionIsThen, the braking control means activates the automatic braking means.To compensate for the decrease in engine braking force and the generation of creep forceSince the drive wheels are automatically braked, the engine braking force decreases and creeps just before the vehicle stops.ForceIt is compensated by the generation of the braking force by the braking control means, and it is possible to prevent an increase in the braking distance and eliminate the driver's uncomfortable feeling without requiring an additional stepping on the brake pedal.
[0055]
  According to the second aspect of the present invention, the state immediately before stopping can be detected from a decrease in the engine speed.
[0056]
  According to the third aspect of the present invention, the state immediately before the stop can be detected from the decrease in the vehicle speed.
[0057]
  According to the invention described in claim 4, since the magnitude of the engine braking force and the magnitude of the creep force depend on the timing at which the fuel supply is restarted, the automatic braking is performed according to the actual fluctuation of the braking force. Braking can be started at an appropriate timing.
[0058]
  According to the fifth aspect of the present invention, it is possible to accurately compensate for the decrease in braking force immediately before the vehicle stops, and to avoid an increase in braking distance without the driver depressing the brake pedal. At the same time, the driver's discomfort can be resolved.
[0059]
  According to the sixth aspect of the present invention, the vehicle can be correctly stopped at the stop position predicted by the driver without increasing the brake pedal immediately before stopping.
[0060]
  According to the seventh aspect of the present invention, it is possible to save energy by terminating automatic braking at the same time that automatic braking is not necessary.
[0061]
  Furthermore, according to the invention described in claim 8, when the driver's intention to decelerate is lost, the automatic braking can be promptly terminated, and the automatic braking that is not desired by the driver can be prevented. it can. Moreover, even after the vehicle has stopped, the automatic braking will not end unless the driver releases the brake pedal, thus avoiding an unexpected decrease in the braking force of the driver after the vehicle is stopped, and the driver feels uncomfortable. It can be prevented from receiving.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of a vehicle equipped with a braking force control device.
FIG. 2 is an explanatory diagram showing the structure of a braking system
FIG. 3 is a block diagram showing a circuit configuration of an electronic control unit.
FIG. 4 is a flowchart for explaining the operation.
FIG. 5 is a time chart for explaining the operation.
FIG. 6 is an explanatory diagram showing the structure of a braking system according to a second embodiment.
FIG. 7 is a diagram schematically showing changes in braking force and driving force immediately before the vehicle stops.
[Explanation of symbols]
E engine
M1 State detection means immediately before stopping
M2 braking control means
V vehicle
W_FL        Front wheel (drive wheel)
W_FR        Front wheel (drive wheel)
T automatic transmission
2 Electronically controlled negative pressure booster (automatic braking means)
4 Hydraulic braking device (automatic braking means)

Claims (8)

In a vehicle equipped with an automatic transmission (T) that transmits driving force of an engine (E) to driving wheels (W _FL , W _FR ),
Automatic braking means (2, 4) capable of braking the drive wheels (W _FL , W _FR ) without the driver's braking operation;
Vehicle (V) is reduced in the engine braking force and an automatic transmission and immediately before stop state detecting means total braking force due to the creep force generated in the (T) is detected to be in the stop just before state to decrease (M1) ,
Said said actuating the automatic braking means (2,4) when the stop just before state by the stop state immediately before the detection means (M1) is detected, so as to compensate for the reduction and creep force generated in the engine braking force and the drive wheels (W _FL, W _FR) automatically brake to brake controlling means (M2), the
A braking force control apparatus for a vehicle, comprising: 2. The vehicle according to claim 1, wherein the state immediately before stop detecting means (M <b> 1) detects the state immediately before stopping on the condition that the rotational speed of the engine (E) has decreased to a predetermined rotational speed. Braking force control device. 2. The vehicle according to claim 1, wherein the state immediately before stop detecting means (M <b> 1) detects the state immediately before stop on the condition that the vehicle speed has decreased to a predetermined vehicle speed set according to a shift position. Braking force control device. The engine (E) includes a fuel injection device that stops fuel supply during engine brake operation and restarts fuel supply immediately before the vehicle stops.
  2. The braking force control apparatus for a vehicle according to claim 1, wherein the state immediately before stop detecting means (M1) detects the state immediately before stopping on condition that the fuel supply is resumed. The braking force generated by the automatic braking means (2, 4) is set based on the deviation between the engine braking force at the start of braking by the automatic braking means (2, 4) and the creep force when the vehicle is stopped. The braking force control apparatus for a vehicle according to any one of claims 1 to 4. The vehicle according to any one of claims 1 to 4, wherein the rising gradient of the braking force generated by the automatic braking means (2, 4) increases as the pedaling force of the driver's brake operation increases. Braking force control device. The braking force control device for a vehicle according to any one of claims 1 to 6, wherein the automatic braking by the automatic braking means (2, 4) ends when the vehicle (V) stops. 7. The braking force control device for a vehicle according to claim 1, wherein the automatic braking by the automatic braking means (2, 4) is finished when the driver's braking operation is finished. 7. .

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