JP3454091B2 - Braking force control device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a braking force control device, and more particularly to a braking force control device suitable as a device for controlling the braking force of a vehicle.

[0002]

2. Description of the Related Art Conventionally, for example, JP-A-4-12126
As disclosed in No. 0, there is known a braking force control device that generates a large braking fluid pressure as compared with a normal time when the brake pedal is depressed at a speed exceeding a predetermined speed.
The driver of the vehicle operates the brake pedal at high speed in order to quickly raise the braking force. According to the above-described conventional braking force control device, when such a brake operation (hereinafter referred to as an emergency brake operation) is performed, a large braking hydraulic pressure is generated as compared with the normal time, so that the driver's request can be properly performed. It is possible to generate a braking force that responds to.

[0003]

When an emergency braking operation is performed, a control for generating a larger braking fluid pressure than in normal times (hereinafter, this control is referred to as brake assist control) is performed by, for example, a master cylinder. And a wheel cylinder, a first on-off valve, a pump that supplies the brake fluid sucked from the master cylinder side to the wheel cylinder, and a second on-off valve that is interposed between the pump and the master cylinder. Can be done in.

According to the above system, the master cylinder and the wheel cylinder are brought into conduction and the master cylinder is closed by opening the first opening / closing valve and closing the second opening / closing valve. And the pump can be cut off. In this case, the wheel cylinder can generate a wheel cylinder pressure P _{W / C} equal to the master cylinder pressure P _{M / C.} As described above, according to the above system, the function as a normal brake device can be realized by realizing the above-mentioned state.

Further, according to the above system, the first opening / closing valve is closed, the second opening / closing valve is opened, and
By activating the pump, the master cylinder and the wheel cylinder can be shut off, and the brake fluid in the master cylinder can be pressurized by the pump and supplied to the wheel cylinder. In this case, a hydraulic pressure higher than the master cylinder pressure P _{M / C} can be generated in the wheel cylinder. Therefore, according to the above system,
Brake assist control can be executed by realizing the above-described state.

By the way, the discharge capacity of a pump depends on its suction
The higher the hydraulic pressure supplied to the side, the higher the hydraulic pressure. Obey
In the above system, the pump is
Da pressure P _{M / C}The higher the pressure, the higher the discharge performance.
In the above system, the discharge capacity of the pump changes
And the wheel lock during brake assist control execution.
Pressure P_{W / C}A change occurs in the boosting characteristic of. Because of this,
Depending on the system described above, the brake assist control
It has been difficult to always obtain a constant boosting characteristic.

The present invention has been made in view of the above points, and uses a system configuration including a pump that sucks in brake fluid from a hydraulic passage that connects a master cylinder and a wheel cylinder, and It is an object of the present invention to provide a braking force control device capable of increasing the wheel cylinder pressure with a constant pressure increasing characteristic without being affected by the value of

[0008]

The above-mentioned object is defined in claim 1.
As described in (1), a brake for sucking the brake fluid from a hydraulic passage that connects the master cylinder and the wheel cylinder is provided, and the brake fluid discharged from the pump is supplied to the wheel cylinder to control the wheel cylinder pressure. the braking force control apparatus for executing hydraulic control, comprising a pressure increasing condition changing means for changing in accordance with pressure increasing condition for supplying the brake fluid from the pump to the wheel cylinder to the master cylinder pressure, the pressure increase condition variable
The way to change is that the lower the master cylinder pressure, the longer the boosting time.
This is achieved by the braking force control device.

In the present invention, when the wheel cylinder pressure is required to be increased during execution of the brake fluid pressure control, the brake fluid discharged from the pump is supplied to the wheel cylinder. The master cylinder pressure is supplied to the suction side of the pump from the hydraulic passage. Therefore, the discharge capacity of the pump changes according to the master cylinder pressure. In the present invention, the pressure increasing condition during execution of the brake fluid pressure control is changed according to the master cylinder pressure so as to cancel the change in the discharge capacity of the pump. Therefore, the wheel cylinder pressure is always increased with a constant pressure increasing characteristic without being affected by the value of the master cylinder pressure. Specifically, in the present invention,
The discharge capacity of the pump decreases as the master cylinder pressure decreases.
To do. Further, in the present invention, execution of brake fluid pressure control
As the master cylinder pressure is lower,
Be phased. Time to increase pressure when pump discharge capacity decreases
Longer, the fluctuations in the discharge capacity of the pump are canceled out.
As a result, a constant pressure increasing characteristic is maintained.

[0010]

[0011]

[0012]

[0013]

[0014]

The above object is as described in claim 2 .
Hydraulic passage that connects the master cylinder and the wheel cylinder
With a pump that draws in brake fluid from the
The brake fluid discharged from the pump.
To the wheel cylinder to control the wheel cylinder pressure.
The braking force control apparatus for executing control over key fluid pressure, said
Supply brake fluid from pump to wheel cylinder
Change the pressure increase condition when changing the master cylinder pressure.
When the pressure condition changing means, the suction control valve arranged between the hydraulic passage and the pump, and the wheel cylinder pressure are required to be increased, the pump is operated and the suction A pressure increasing control means for executing pressure increasing control for opening the control valve, and the pressure increasing condition changing means,
This is achieved by a braking force control device that lengthens the time during which the intake control valve is opened during execution of the pressure increase control as the master cylinder pressure decreases.

Execution of brake fluid pressure control in the present invention
If increasing the wheel cylinder pressure is required during
Brake fluid discharged from the pump to the wheel cylinder
Supplied. On the suction side of the pump, connect the master from the hydraulic passage.
Cylinder pressure is being supplied. Therefore, the discharge capacity of the pump
The force changes according to the master cylinder pressure. The present invention
The pressure increase condition during execution of brake fluid pressure control is
The master cylinder pressure to offset the change in pump discharge capacity.
Will be changed accordingly. Therefore, the wheel cylinder pressure is
Constant constant regardless of the star cylinder pressure value
It is boosted by the boosting characteristic. Specifically, in the present invention,
The pump supplies brake fluid to the wheel cylinder pressure when the intake control valve is open. The discharge capacity of the pump decreases as the master cylinder pressure decreases.
On the other hand, in the present invention, the opening time of the intake control valve is extended as the master cylinder pressure is lower. If the valve opening time of the suction control valve is lengthened when the discharge capacity of the pump decreases, fluctuations in the discharge capacity of the pump are offset, and a constant pressure increasing characteristic is maintained.

Further, the above-mentioned object is, as described in claim 3 , a liquid for connecting a master cylinder and a wheel cylinder.
Equipped with a pump that draws in brake fluid from the pressure passage
Along with the brake fluid discharged from the pump
Supply to the wheel cylinder to control the wheel cylinder pressure
In the braking force control device that executes the brake fluid pressure control,
Supply the brake fluid from the pump to the wheel cylinder.
Change the boosting condition when supplying according to the master cylinder pressure
This is achieved by a braking force control device that includes pressure increasing condition changing means, wherein the pump is a variable displacement pump, and the pressure increasing condition changing means increases the discharge capacity of the pump as the master cylinder pressure decreases.

In the present invention, execution of brake fluid pressure control
If increasing the wheel cylinder pressure is required during
Brake fluid discharged from the pump to the wheel cylinder
Supplied. On the suction side of the pump, connect the master from the hydraulic passage.
Cylinder pressure is being supplied. Therefore, the discharge capacity of the pump
The force changes according to the master cylinder pressure. The present invention
The pressure increase condition during execution of brake fluid pressure control is
The master cylinder pressure to offset the change in pump discharge capacity.
Will be changed accordingly. Therefore, the wheel cylinder pressure is
Constant constant regardless of the star cylinder pressure value
It is boosted by the boosting characteristic. Specifically, in the present invention,
The discharge capacity of the pump tends to decrease as the master cylinder pressure decreases. In the present invention, the discharge capacity of the variable displacement pump is increased as the master cylinder pressure is lower so that the change is offset. When the discharge capacity of the variable displacement pump is changed as described above, fluctuations in the discharge capacity of the pump are offset, and a constant pressure increasing characteristic is maintained.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a system configuration diagram of a braking force control device according to an embodiment of the present invention. The braking force control device of the present embodiment is a device suitable as a braking force control device mounted on a front engine / front drive type vehicle (FF vehicle). The braking force control device of the present embodiment is controlled by an electronic control unit 10 (hereinafter referred to as ECU 10).

The braking force control device has a brake pedal 12. A brake switch 14 is arranged near the brake pedal 12. Brake switch 14
Outputs an ON signal when the brake pedal 12 is depressed. The ECU 10 uses the brake switch 14
It is determined whether or not the brake pedal 12 is depressed based on the output signal of.

The brake pedal 12 is connected to a vacuum booster 16. The vacuum booster 16
When the brake pedal 12 is depressed, an assist force Fa having a predetermined boosting ratio with respect to the brake pedal force F is generated. A master cylinder 18 is fixed to the vacuum booster 16. A first hydraulic chamber 20 and a second hydraulic chamber 22 are formed inside the master cylinder 18. In the first hydraulic pressure chamber 20 and the second hydraulic pressure chamber 22, a master cylinder pressure P _{M / C} corresponding to the resultant force of the brake pedal force F and the assist force Fa is generated.

A reservoir tank 24 is arranged above the master cylinder 18. The master cylinder 18 and the reservoir tank 24 are brought into conduction only when the depression of the brake pedal 12 is released. A first hydraulic pressure passage 26 and a second hydraulic pressure passage 28 communicate with the first hydraulic pressure chamber 20 and the second hydraulic pressure chamber 22 of the master cylinder 18, respectively.

A hydraulic pressure sensor 29 is arranged in the first hydraulic pressure passage 26. The hydraulic pressure sensor 29 is provided in the first hydraulic pressure passage 26.
Of the master cylinder pressure P _{M / C} generated by the master cylinder 18 is output. The output signal pMC of the hydraulic pressure sensor 29 is supplied to the ECU 10. The ECU 10 detects the master cylinder pressure P _{M / C} based on the output signal pMC.

In the first hydraulic passage 26, a first master cut solenoid 30 (hereinafter referred to as SMC _-1 30) and a first reservoir cut solenoid 32 (hereinafter SRC _-1 32).
Is called). On the other hand, the second hydraulic passage 28 has a second master cut solenoid 34 (hereinafter referred to as SMC _-2).
34) and the second reservoir cut solenoid 36.
(Hereinafter, SRC- ₂ 36) is in communication.

Constant pressure release valves 38 and 40 are provided inside the SMC- ₁ 30 and SMC- ₂ 34. SMC _-1
In FIG. 30, the hydraulic passage 4 is provided corresponding to the right rear wheel RR.
2 and the hydraulic passage 44 provided corresponding to the left front wheel FL communicates with each other. Similarly, the SMC- ₂ 34 is in communication with a hydraulic passage 46 provided corresponding to the left rear wheel RL and a hydraulic passage 48 provided corresponding to the right front wheel FR.

The SMC _-1 30 and SMC _-2 34 maintain the valve open state in the normal state, and when the drive signal is supplied from the ECU 10, the first hydraulic pressure passage 26 and the hydraulic pressure passages 42, 44 are connected. Alternatively, it is a two-position solenoid valve that connects the second hydraulic pressure passage 28 and the hydraulic pressure passages 46 and 48 to each other via constant pressure release valves 38 and 40, respectively. Each of SRC- ₁ 32 and SRC- ₂ 36 is a two-position solenoid valve which maintains a valve closed state in a normal state and is opened by a drive signal supplied from the ECU 10.

A check valve 50 is arranged between the first hydraulic pressure passage 26 and the hydraulic pressure passages 42, 44. The check valve 50
This is a one-way valve that allows only the flow of fluid from the first hydraulic pressure passage 26 side toward the hydraulic pressure passages 42, 44 side. Similarly, a check valve 52 is arranged between the second hydraulic pressure passage 28 and the hydraulic pressure passages 46 and 48. The check valve 52 is a one-way valve that allows only the flow of fluid from the second hydraulic pressure passage 28 side toward the hydraulic pressure passages 46, 48 side.

In the hydraulic passage 42 corresponding to the right rear wheel RR,
A right rear wheel holding solenoid 54 (hereinafter referred to as SRRH 54) is in communication. Similarly, in the hydraulic passage 44 corresponding to the left front wheel FL, the left front wheel holding solenoid 56 (hereinafter, referred to as SF
LH56) indicates the hydraulic passage 4 corresponding to the left rear wheel RL.
6 is a left rear wheel holding solenoid 58 (hereinafter referred to as SRLH58
(Also referred to as “”), but also the hydraulic passage 48 corresponding to the right front wheel FR.
A right front wheel holding solenoid 60 (hereinafter, referred to as SFRH60) communicates with each. Hereinafter, these solenoids are collectively referred to as "holding solenoid S ** H". The holding solenoid S ** H is a two-position solenoid valve that normally maintains the valve open state and is closed when a drive signal is supplied from the ECU 10.

A right rear wheel pressure reducing solenoid 62 (hereinafter, referred to as SRRR 62) communicates with the SRRH 54. Similarly, the left front wheel pressure reducing solenoid 64 (hereinafter referred to as SFLR64) is provided in the SFLH 56, and the left rear wheel pressure reduction solenoid 66 (hereinafter referred to as SRLR66) is provided in the SRLH 58.
Further, right front wheel depressurizing solenoids 68 (hereinafter referred to as SFRR 68) communicate with the SFRH 60, respectively. Hereinafter, these solenoids will be collectively referred to as "pressure reducing solenoid S ** R". Pressure reducing solenoid S ** R is
It is a two-position solenoid valve that maintains the valve closed state in the normal state and is opened when the drive signal is supplied from the ECU 10.

Wheel cylinders 70, 72, 74 and 76 are in communication with the holding solenoids S ** H of the respective wheels. In addition, the wheel cylinders 70, 72, 74, 76
The check valves 78, 80, 82, 84 communicate with each other. The check valves 78, 80, 82, 84 are provided on the hydraulic cylinders 42, 4 from the wheel cylinders 70, 72, 74, 76 side.
This is a one-way valve that allows only the flow of fluid toward the 4, 46, 48 side.

The SRRR 62 and the SFLR 64 communicate with the pressure reducing passage 88. Similarly, the SRLR 66 and the SFRR 68 communicate with the pressure reducing passage 90. Auxiliary reservoirs 92 and 94 communicate with the depressurization passages 88 and 90. The auxiliary reservoirs 92 and 94 are in communication with the suction holes of the pumps 100 and 102 via the check valves 96 and 98.
The suction holes of the pumps 100 and 102 also have an SRC _-1 3
2 or SRC- ₂ 36 are in communication.

The pumps 100 and 102 are provided with auxiliary reservoirs 92 and 94 when a drive signal is supplied from the ECU 10.
Brake fluid stored in or SRC
Brake fluid introduced through _-1 32 or SRC _-2 36 is discharged from the discharge hole. Pump 100,1
The discharge hole 02 is communicated with the dampers 104 and 106. The dampers 104 and 106 absorb the pulsation generated in the discharge pressure of the pumps 100 and 102. Dampers 104, 106
Communicate with the hydraulic passages 44 and 46, respectively.

The braking force control system of this embodiment comprises wheel speed sensors 108, 110, 112 and 114. The wheel speed sensors 108, 110, 112, 114 output pulse signals at a cycle corresponding to the rotation speed of each wheel. The output signals of the wheel speed sensors 108, 110, 112, 114 are E
Supplied to CU10. The ECU 10 detects the rotation speed V _W of each wheel based on the output signals of the wheel speed wheel speed sensors 108, 110, 112, 114.

Next, with reference to FIGS. 2 to 11 together with FIG. 1, the operation of the braking force control system of this embodiment will be described.
The braking force control device of the present embodiment functions as a normal braking device (hereinafter referred to as a normal braking function) and an antilock brake by switching the state of various electromagnetic valves arranged in the hydraulic circuit. A system function (hereinafter referred to as ABS function) and a function to generate wheel cylinder pressure P _{W / C} higher than the master cylinder pressure P _{M / C} (hereinafter referred to as brake assist function) are realized. To do.

FIG. 1 shows a control for realizing a normal brake function (hereinafter referred to as normal brake control) or A
The state realized during execution of control for realizing the BS function (hereinafter referred to as ABS control) is shown. Hereinafter, the state shown in FIG. 1 is referred to as a normal braking state. During execution of the normal brake control, as shown in FIG. 1, all the electromagnetic valves included in the braking force control device are turned off.
According to the normal braking state, the wheel cylinders 70, 72, 74, 76 of all the wheels communicate with the master cylinder 18. In this case, the wheel cylinder pressure P _{W / C} of each wheel is
It is always controlled to be equal to the master cylinder pressure P _{M / C.} Therefore, according to the normal braking state shown in FIG. 1, the normal braking function can be realized.

During execution of the ABS control, as shown in FIG. 1, SMC _-1 30, SRC _-2 32, SMC _-1 34 and SR.
With the C- ₂ 36 turned off, the pumps 100, 1
02 is activated and the holding solenoid S ** H
And the depressurizing solenoid S ** R is driven appropriately as required by the ABS. Hereinafter, a state realized during execution of the ABS control is referred to as an ABS state.

According to the ABS state, the master cylinder pressure P _{M / C} can be introduced to all of the four hydraulic passages 42, 44, 46 and 48 provided corresponding to the respective wheels. If the holding solenoid S ** H is opened and the pressure reducing solenoid S ** R is closed in this state, the wheel cylinder pressure P _{W / C} of each wheel is directed to the master cylinder pressure P _{M / C.} Can be increased. Hereinafter, this state is referred to as (i) pressure increasing mode. In the above state, the holding solenoid S *
When both * H and the pressure reducing solenoid S ** R are closed, the wheel cylinder pressure P _{W / C} of each wheel can be maintained. Hereinafter, this state is referred to as (ii) holding mode.
Further, in the above state, if the holding solenoid S ** H is closed and the pressure reducing solenoid S ** R is opened, the wheel cylinder pressure P _{W / C} of each wheel can be reduced. . Hereinafter, this state is referred to as (iii) depressurization mode.

When the ABS control is started, the ECU 10
Realizes (i) pressure increasing mode, (ii) holding mode, and (iii) pressure reducing mode for each wheel as appropriate so that an excessive slip ratio does not occur in each wheel. When the holding solenoid S ** H and the pressure reducing solenoid S ** R are controlled as described above, the wheel cylinder pressure P _{W / C of} all wheels is controlled.
However, the pressure is controlled to an appropriate pressure that does not cause an excessive slip ratio on the corresponding wheels. Thus, according to the above control, the ABS function can be realized in the braking force control device.

2 to 4 are controls for realizing the brake assist function (hereinafter referred to as BA function) (hereinafter, referred to as BA
The state realized during execution of control) is shown. ECU
When the driver performs an emergency braking operation, 10 starts BA control so as to generate a larger braking force than in a normal time. During execution of the BA control, the ECU 10
Thereby, any one of the states shown in FIGS. 2 to 4 is appropriately realized.

FIG. 2 shows the assist pressure increasing state realized during execution of the BA control. The assist pressure increase state is BA
It is realized when it is necessary to increase the wheel cylinder pressure P _{W / C} of each wheel during execution of the control. In the system of the present embodiment, the assist pressure increasing state is as shown in FIG.
SMC _-1 30, SRC _-1 32, SMC _-2 34 and SR
C- ₂ 36 turned on (SMC- ₁ 30 and SMC- ₂ 34
Is closed, SRC _-1 32 and SRC _-2 36 are opened, and the pumps 100 and 102 are turned on.

According to the assist pressure increasing state, the master cylinder 18 and the suction holes of the pumps 100 and 102 are in communication with each other. In this case, the pumps 100 and 102 can suck the brake fluid from the master cylinder 18 and discharge the high-pressure brake fluid to the hydraulic pressure passages 42 and 44 or the hydraulic pressure passages 46 and 48. According to the assist pressure increasing state, the hydraulic pressure passages 42, 44 and the hydraulic pressure passages 46, 4
8 is separated from the master cylinder 18 by constant pressure release valves 38 and 40 built in SMC _-1 30 or SMC _-2 34, respectively. In this case, the pumps 100, 10
The brake fluid pumped by 2 receives the fluid pressure passage 4
It is supplied to the wheel cylinders 70, 72, 74 and 76 of the respective wheels via 2, 44, 46 and 48.

Therefore, according to the assist pressure increasing state shown in FIG. 1, by pumping the brake fluid in the master cylinder 18 by the pumps 100 and 102, the wheel cylinder pressure P _{W / C} of each wheel is changed to the master cylinder. The liquid pressure can be increased to a pressure higher than the pressure P _{M / C.} FIG. 3 shows an assist pressure holding state realized during execution of the BA control. The assist pressure increase state is realized when it is necessary to maintain the wheel cylinder pressure P _{W / C} of each wheel during execution of the BA control. In the system of the present embodiment, the assist pressure holding state is SMC _-1 30 and SMC _{-2 as} shown in FIG.
34 is turned on (valve closed state), and the pump 10
This is realized by turning 0 and 102 on.

According to the assist pressure holding state, SRC _-1 3
2 and the SRC _- 236, the suction holes of the pumps 100 and 102 and the master cylinder 18 can be shut off. In this case, the pumps 100 and 102 cannot suck the brake fluid from the master cylinder 18. Further, inside the auxiliary reservoirs 92 and 94, the ABS
Brake fluid is not stored before control is started. Therefore, when the assist pressure holding state is realized, the pump 100, 102 stops pumping the brake fluid. Therefore, according to the assist pressure holding state, the wheel cylinder pressures P _{W / C} of all the wheels can be held at a constant value.

FIG. 4 shows the assist pressure reducing state realized during execution of the BA control. The assist pressure reduction state is BA
It is realized when it is necessary to reduce the wheel cylinder pressure P _{W / C} of each wheel during execution of the control. In this example,
The assist pressure reducing state is realized by turning off all the solenoids as shown in FIG. According to the assist pressure reduction state, the SRC _-1 32 and SRC _-2 36 are closed. In this case, the pumps 100 and 102 cannot pump the brake fluid. Further, according to the assist pressure reducing state, the wheel cylinder 7 of each wheel is
0, 72, 74, 76 are SMC- ₁ 30 or SMC3
4 to communicate with the master cylinder 18. For this reason,
According to the assist pressure reduction state, the wheel cylinder pressure P _{W / C} of all wheels can be reduced with the master cylinder pressure P _{M / C} as the lower limit value.

FIG. 5 shows changes in the master cylinder pressure P _{M / C} and the wheel cylinder pressure P _{W / C} when the driver performs an emergency braking operation. When the driver performs an emergency braking operation, the master cylinder pressure P _{M / C} is rapidly increased as indicated by a broken line in FIG. Based on the output signal pMC of the hydraulic pressure sensor 29, the ECU 10 determines that the master cylinder pressure P _{M / C} is sudden and
When it can be recognized that the pressure has been increased to a sufficiently large value, it is determined that the emergency braking operation has been performed. And ECU1
When 0 determines that the emergency braking operation is executed, the BA control is started thereafter.

When BA control is started in the braking force control device, first, (I) start pressure increasing mode is executed (period in FIG. 5). Start boosting mode is set to the specified duty ratio Duty
1 is realized by repeating the assist pressure increasing state shown in FIG. 2 and the assist pressure holding state shown in FIG. More specifically, SMC _-1 30 and SMC _-2 3
4 is kept in the ON state (valve closed state), and the pumps 100, 1
02 in operation and SRC _-1 32 and S
It is realized by repeatedly turning on and off the RC _-2 36 at a predetermined duty ratio Duty1.

The start pressure increasing mode is a predetermined pressure increasing time T _STA.
Will be continuously executed during the period. The pressure increase time T _STA is set to a time required to increase the wheel cylinder pressure P _{W / C} by a predetermined assist pressure Pa as compared with the master cylinder pressure P _{M / C.} Further, the predetermined assist pressure Pa is a pressure required to generate a predetermined assist deceleration G ₀ in the vehicle. Therefore, when the start pressurizing mode is performed, the vehicle, a large deceleration G + G ₀ by a predetermined assist deceleration G ₀ relative to the deceleration G generated by the normal brake control
Occurs.

In the braking force control device, when the (I) start pressure increasing mode ends, thereafter, (II) assist pressure increasing mode, (III) assist pressure reducing mode, ( Any one of (IV) assist pressure holding mode, (V) assist pressure gentle increase mode, and (VI) assist pressure gentle decrease mode is executed. FIG. 6 shows an example of a map referred to by the ECU 10 in order to determine the mode to be executed next to the start pressure increasing mode. In FIG. 6, the horizontal axis indicates the hydraulic pressure sensor 2
9 is the change rate ΔpMC of the output signal pMC of FIG.

If the master cylinder pressure P _{M / C} has a positive rate of change at the end of the start pressure increasing mode, it can be determined that the driver is requesting a larger braking force. The ECU 10 determines that the driver is requesting a larger braking force when the change rate ΔpMC that exceeds the predetermined value K ₁ (> 0) occurs at the time when the start pressure increasing mode ends. In this case, the ECU 10 determines the mode to be executed subsequent to the start pressure increasing mode to the (II) assist pressure increasing mode.

If the master cylinder pressure P _{M / C} has a negative rate of change at the end of the start pressure increasing mode, it can be determined that the driver is requesting a reduction in the braking force. The ECU 10 determines that the driver is requesting the reduction of the braking force when the change rate ΔpMC that is less than the predetermined value K ₂ (<0) occurs at the time when the start pressure increasing mode ends. In this case, the ECU 10 determines the mode to be executed next to the start pressure increasing mode to be (III) assist pressure reducing mode.

When the start pressure increasing mode is completed,
Star cylinder pressure P_{M / C}If there is no significant change in
If it is determined that the driver is requesting to hold the braking force,
be able to. The ECU 10 finishes the start pressure increasing mode.
K when₂≤ΔpMC≤K ₁Change rate ΔpMC that satisfies
If the driver has requested that the braking force be retained,
Determine that In this case, the ECU 10 controls the start pressure increasing mode.
Mode to be executed next to the (IV) assist pressure holding mode.
Decide to do.

(II) The assist pressure increasing mode is used when the brake operation amount is greatly increased at the end of the above-described start pressure increasing mode, and when the assist pressure holding mode described later is being executed or the assist pressure gradually increasing. This is executed when the brake operation amount is greatly increased during execution of the mode (FIG. 5).
Medium period). The assist pressure increasing mode is realized by repeating the assist pressure increasing state shown in FIG. 2 and the assist pressure holding state shown in FIG. 3 at a predetermined duty ratio Duty2. The duty ratio Duty2 used in the assist pressure increasing mode may be the same as or different from the duty ratio Duty1 used in the start pressure increasing mode. According to the assist pressure increasing mode, when the brake operation amount is greatly increased, the wheel cylinder pressure P _{W / C} of each wheel is rapidly increased in a region higher than the master cylinder pressure P _{M / C.} Can be pressed.

FIG. 7 shows an example of a map referred to by the ECU 10 to determine the mode to be executed during execution of the assist pressure increasing mode. In FIG. 7, the horizontal axis represents the rate of change ΔpMC of the output signal pMC of the hydraulic pressure sensor 29.
While the assist pressure increasing mode is being executed, the master cylinder pressure P
_{If the M / C} continues to increase, it can be determined that the driver is requesting a larger braking force. ECU
10 is a predetermined value K during execution of the assist pressure increasing mode.
_{If the} change rate ΔpMC exceeds ₃ (> 0), it is determined that the driver is requesting a larger braking force. In this case, the ECU 10 continuously sets the mode to be executed to the assist pressure increasing mode.

During execution of the assist pressure increasing mode,
If the master cylinder pressure P _{M / C} does not increase significantly, it can be determined that the driver no longer requests an increase in braking force. The ECU 10 changes the rate of change Δ exceeding a predetermined value K ₃ (> 0) during execution of the assist pressure increasing mode.
When pMC does not occur, it is determined that the driver has not requested an increase in braking force. In this case, the ECU 10
The assist pressure holding mode is determined as the mode to be executed.

(III) In the assist pressure reducing mode, when the brake operation amount is greatly reduced at the end of the above-mentioned start pressure increasing mode, and when the assist pressure holding mode to be described later is being executed or the assist pressure gradually decreasing mode. This is executed when the brake operation amount is greatly reduced during execution of (in FIG. 5, period). In the assist pressure reducing mode, in the assist pressure holding state shown in FIG. 3 at a predetermined duty ratio Duty3,
This is realized by repeating the assist pressure reducing state shown in FIG. More specifically, the SRC _-1 32 and SRC _-2 36 are maintained in the off state (valve closed state), the pumps 100 and 102 are maintained in the operating state, and the SMC _-1 3
0 and SMC- ₂ 34 are repeatedly turned on and off at a predetermined duty ratio Duty3. According to the assist pressure reduction mode, the wheel cylinder pressure P _{W / C} of each wheel is reduced when the brake operation amount is greatly reduced.
The master cylinder pressure P _{M / C} can be used as a lower limit value to rapidly reduce the pressure.

FIG. 8 shows an example of a map referred to by the ECU 10 to determine the mode to be executed during execution of the assist pressure reduction mode. In FIG. 8, the horizontal axis represents the change rate ΔpMC of the output signal pMC of the hydraulic pressure sensor 29.
During execution of the assist pressure reduction mode, the master cylinder pressure P
_{If the M / C} continues to decrease, it can be determined that the driver is requesting a smaller braking force. ECU
10 is a predetermined value K during execution of the assist pressure increasing mode.
_{If the} change rate ΔpMC is less than ₄ (<0), it is determined that the driver requests a smaller braking force. In this case, the ECU 10 continuously sets the mode to be executed to the assist pressure reducing mode.

During execution of the assist pressure reducing mode,
If the master cylinder pressure P _{M / C} does not decrease significantly, it can be determined that the driver no longer requires a decrease in braking force. The ECU 10 changes the rate of change Δ below a predetermined value K ₄ (<0) during execution of the assist pressure reducing mode.
When pMC does not occur, it is determined that the driver does not request reduction of the braking force. In this case, the ECU 10
The assist pressure holding mode is determined as the mode to be executed.

(IV) In the assist pressure holding mode, a large increase or decrease in the brake operation amount occurs at the end of the above-described start pressure increasing mode or during the execution of the above assist pressure increasing mode or assist pressure reducing mode. When it is detected that there is not, and after the assist pressure gradual increase mode or the assist pressure gradual decrease mode, which will be described later, is executed for a predetermined period of time (the period in FIG. 5,).

The assist pressure holding mode is realized by maintaining the assist pressure holding state shown in FIG.
According to the assist pressure holding mode, the wheel cylinder pressure P _{W / C} of each wheel can be maintained at a constant value when the brake operation amount is not greatly increased or decreased. FIG. 9 shows an example of a map referred to by the ECU 10 to determine the mode to be executed during execution of the assist pressure holding mode.
In FIG. 9, the horizontal axis represents the output signal p of the hydraulic pressure sensor 29.
The change rate of MC is ΔpMC. The vertical axis represents the output value pMCSTA at the time of change from the output signal pMC of the hydraulic pressure sensor 29.
Is the value obtained by subtracting. The output value pMCSTA at the time of change is the value of the output signal pMC output from the hydraulic pressure sensor 29 at the time when the assist pressure holding mode is started. Therefore,
In FIG. 9, the vertical axis corresponds to the amount of change in the increasing direction of the output signal pMC after the assist pressure holding mode is started.

If the master cylinder pressure P _{M / C} is rapidly increasing during execution of the assist pressure holding mode, it can be determined that the driver is requesting a rapid increase in braking force. E
The CU ₁₀ changes the output signal pMC to exceed the predetermined value P ₁ (that is, pMC−pMCSTA) after the start of the assist pressure holding mode and before the predetermined time T _MODE1 has elapsed.
> P ₁ ) occurs, and the rate of change ΔpMC exceeds a predetermined value K ₅ (> 0) at the time of the change, the driver requests a sudden increase in braking force. Determine that In this case, the ECU 10 changes the mode to be executed from the assist pressure holding mode to the assist pressure increasing mode.

If the master cylinder pressure P _{M / C} sharply decreases during execution of the assist pressure holding mode, it can be determined that the driver is requesting a sharp decrease in the braking force. E
The CU 10 decreases the output signal pMC by exceeding the predetermined value P ₄ (that is, pMC−pMCSTA) after the start of the assist pressure holding mode and before the predetermined time T _MODE1 elapses.
<Until reduction) and P ₄ is satisfied, and the rate of change ΔpMC at the time the drop has occurred is the driver when below the predetermined value K ₆ (<0) to request a reduction in the sudden braking amount Determine that In this case, the ECU 10 changes the mode to be executed from the assist pressure holding mode to the assist pressure reducing mode.

When the master cylinder pressure P _{M / C} is gradually increasing during the execution of the assist pressure holding mode, it can be determined that the driver is requesting the gentle increase of the braking force. After the assist pressure holding mode is started, the ECU 10 does not satisfy the above condition for shifting to the assist pressure increasing mode or the assist pressure reducing mode, and the ECU 10 continuously outputs the output signal pMC for a predetermined time T _MODE1. Value P ₂ (0 <
Changes above P ₂ <P ₁ (ie pMC-pMC
(Change satisfying STA> P ₂ ) occurs, it is determined that the driver is requesting a gradual increase in braking force. In this case, the ECU 10 changes the mode to be executed from the assist pressure holding mode to the assist pressure gradual increase mode.

If the master cylinder pressure P _{M / C} is gradually decreasing during execution of the assist pressure holding mode, it can be determined that the driver is requesting a gentle decrease in braking force. After the assist pressure holding mode is started, the ECU 10 does not satisfy the above condition for shifting to the assist pressure increasing mode or the assist pressure reducing mode, and the ECU 10 continuously outputs the output signal pMC for a predetermined time T _MODE1. Value P ₃ (0>
P _3> P ₄₎ decreases below (i.e., pMC-pMC
If the STA <lowering satisfying P ₃₎ has occurred, it is determined that the driver is requesting a moderate reduction of the braking force. In this case, the ECU 10 changes the mode to be executed from the assist pressure holding mode to the assist pressure gradual decrease mode.

During execution of the assist pressure holding mode,
Master cylinder pressure P_{M / C}If there is no significant change in
Can determine that the driver is requesting that the braking force be maintained.
It The ECU 10 has started the assist pressure holding mode.
After that, the change amount of the output signal pMC is a predetermined value P₂And P₃Between
(That is, P₃≤pMC-pMCSTA≤
P ₂Is satisfied), the driver requests that the braking force be maintained.
Judge that you are doing. In this case, the ECU 10
The pressure holding mode is maintained as the mode to be executed.

(V) The assist pressure gradual increase mode is executed when a gradual increase in the brake operation amount is detected during execution of the assist pressure holding mode as described above. When the execution of the assist pressure gentle increase mode is requested, the ECU 10 maintains the braking force control device in the assist pressure increase state shown in FIG. 2 for a predetermined short time T _MODE2 . Then, the ECU 10
As long as a rapid increase in the brake operation amount is not detected, after the predetermined time T _MODE2 has elapsed, the assist pressure slowly increasing mode is ended and the assist pressure holding mode is restarted. According to the assist pressure gentle increase mode, the wheel cylinder pressure P _{W / C} of each wheel can be intermittently increased when the brake operation amount is gradually increased.

FIG. 10 shows an example of a map referred to by the ECU 10 to determine the mode to be executed during execution of the assist pressure moderate increase mode. In FIG. 10, the horizontal axis represents the change rate ΔpMC of the output signal pMC of the hydraulic pressure sensor 29. Further, the vertical axis represents the amount of change pMC-pMCST generated in the output signal pMC after the assist pressure moderately increasing mode is started.
It is A.

If the master cylinder pressure P _{M / C} is rapidly increasing during execution of the assist pressure gradual increase mode, it can be determined that the driver is requesting a rapid increase in the braking force. E
The CU 10 changes the output signal pMC beyond the predetermined value P ₅ (that is, pMC−pMCSTA) after the start of the assist pressure gradual increase mode and before the predetermined time T _MODE2 has elapsed.
> P ₅ ) occurs and the rate of change ΔpMC exceeds a predetermined value K ₇ (> 0) at the time of the change, the driver requests a sudden increase in braking force. Determine that In this case, the ECU 10 changes the mode to be executed from the assist pressure gentle increase mode to the assist pressure increase mode.

When the master cylinder pressure P _{M / C} is not suddenly increased during execution of the assist pressure gradual increase mode,
It can be determined that the driver does not request a sudden increase in braking force. If the above condition for shifting to the assist pressure increasing mode is not satisfied before the predetermined time T _MODE2 elapses after the assist pressure gradually increasing mode is started, the ECU 10 determines that the driver rapidly brakes. Judge that it has not requested the increase of. In this case, the ECU 10 changes the mode to be executed from the assist pressure gentle increase mode to the assist pressure holding mode.

(VI) The assist pressure slow-down mode is as described above.
The brake operation amount during execution of the assist pressure holding mode.
It is executed when a gradual drop is detected (Fig. 5, middle term).
while). When the execution of the assist pressure slowdown mode is requested,
The ECU 10 has a predetermined short time T _MODE3Only braking force control device
The apparatus is maintained in the assist pressure reducing state shown in FIG. So
Then, the ECU 10 detects the sudden decrease in the brake operation amount.
Unless otherwise known, the predetermined time T_MODE3After the
End the cyst pressure reduction mode and restart the assist pressure holding mode.
Start the mode. According to the assist pressure reduction mode,
If the operation amount of the
Wheel cylinder pressure P_{W / C}Can be decompressed intermittently.
Wear.

FIG. 11 shows an example of a map referred to by the ECU 10 to determine the mode to be executed during execution of the assist pressure moderately decreasing mode. In FIG. 11, the horizontal axis represents the rate of change ΔpMC of the output signal pMC of the hydraulic pressure sensor 29. Further, the vertical axis represents the amount of change pMC-pMCST generated in the output signal pMC after the assist pressure gradual decrease mode is started.
It is A.

If the master cylinder pressure P _{M / C} is drastically reduced during execution of the assist pressure gradual reduction mode, it can be determined that the driver is requesting a drastic reduction of the braking force. E
The CU 10 lowers the output signal pMC by more than a predetermined value P ₆ (that is, pMC−pMCSTA) after the start of the assist pressure gradual decrease mode and before the predetermined time T _MODE3 has elapsed.
If the rate of change ΔpMC is less than a predetermined value K ₈ (<0) at the time of the occurrence of <a decrease that satisfies P ₆ ) and the decrease occurs, the driver requests a sudden decrease in braking force. Determine that In this case, the ECU 10 changes the mode to be executed from the assist pressure gentle increase mode to the assist pressure decrease mode.

When the master cylinder pressure P _{M / C} does not suddenly decrease during execution of the assist pressure gradual decrease mode,
It can be determined that the driver does not request a sudden decrease in braking force. If the above condition for shifting to the assist pressure reducing mode is not satisfied before the predetermined time T _MODE3 has elapsed after the assist pressure gradually decreasing mode has been started, the ECU 10 determines that the driver has a sudden braking amount. It is judged that the reduction is not requested. In this case, the ECU 10 changes the mode to be executed from the assist pressure gradual reduction mode to the assist pressure holding mode.

As described above, according to the braking force control apparatus of the present embodiment, when the driver performs an emergency braking operation, the BA control is executed, so that the wheel cylinder pressure P _{W / C of} each wheel is increased. Can be increased to a pressure higher than the master cylinder pressure P _{M / C.} Further, according to the braking force control device of the present embodiment, during execution of the BA control, an increase / decrease in the brake operation amount of the driver is detected based on the output signal pMC of the hydraulic pressure sensor 29, and the brake operation amount is detected. The wheel cylinder pressure P _{W / C} can be increased or decreased according to the increase or decrease of Therefore, according to the braking force control device of the present embodiment,
During execution of the BA control, the braking force can be increased or decreased according to the driver's intention.

Next, referring to FIG. 12 to FIG.
A characteristic part of the braking force control device of the embodiment will be described. Figure 1
2 is a discharge capacity of the pump 100 and the pump 102 and a master
Cylinder pressure P_{M / C}Shows the relationship with. Braking force control of this embodiment
In the control device, on the suction side of the pumps 100, 102,
From the first hydraulic pressure passage 26 and the second hydraulic pressure passage 28,
Linda pressure P _{M / C}Is supplied. Pump 100, 102
The higher the fluid pressure introduced to the suction side, the higher the discharge
Exercise your ability. Therefore, the discharge of the pump 100, 102
The output capacity is as shown in FIG._{M / C}
The higher the pressure, the higher.

The pumps 100 and 102 are used as hydraulic pressure sources.
Cylinder pressure P_{W / C}To increase the pressure of
Pressure P_{W / C}Pumps 100 and 102 have high discharge capacity.
The more the pressure increases, the steeper the pressure increases. Therefore, the actual BA control
Wheel cylinder pressure P during line_{W / C}Intensification gradient that appears in
Specifically, the braking force control device is in the assist pressure increasing state.
Wheel cylinder pressure P_{W / C}Pressure increase gradient appearing in
Is the master cylinder pressure P _{M / C}The higher the pressure, the steeper
Become.

The braking force control system according to the present embodiment realizes the assist pressure increasing state to realize the wheel cylinder pressure P.
_{Although the} pressure increase gradient appearing in _{W / C} is affected by the master cylinder pressure P _{M / C} as described above, (I) start pressure increase mode, (II) assist pressure increase mode, and (V ) The feature is that the wheel cylinder pressure P _{W / C} is always increased with a constant characteristic as the assist pressure moderate increase mode is executed.

FIG. 13 shows a partial flowchart of the main routine executed by the ECU 10. The ECU 10
By executing the series of processes shown in FIG. 13, (I) when execution of the start pressure increasing mode is requested, the assist pressure P is always constant without being influenced by the master cylinder pressure P _{M / C.}
a is generated. The series of processes shown in FIG. 13 is executed under the condition that the BA control execution condition is satisfied. FIG.
A series of processing shown in (1) is started from step 120.

At step 120, it is judged if execution of the start pressure increasing mode is requested. The start pressure increasing mode is requested immediately after the execution condition of the BA control is satisfied. If it is determined in step 120 that the start pressure increasing mode is not required, it can be determined that the start pressure increasing mode has already been executed. In this case, thereafter, other processing not shown in FIG. 13 is executed. On the other hand, if it is determined that the start pressure increasing mode is requested, then step 122 is performed.
The process of is executed.

At step 122, the output signal pMC of the hydraulic pressure sensor 29 is stored as the change-time output value pMCSTA. According to the above process, the change output value pMCSTA
Is the output signal pM at the time when the start boosting mode is started.
C is stored. In step 124, the pressure increasing time T _STA
Is calculated. The pressure increase time T _STA is the time during which the start pressure increase mode should be continued, as described above. In this step 124, the pressure boosting time T _STA is the output value pMCSTA at the time of change.
Is calculated based on.

FIG. 14 shows an example of a map defining the relationship between the pressure increase time T _STA and the change output value pMC. ECU1
In step 124, 0 calculates the pressure increasing time T _STA according to the map shown in FIG. According to the map shown in FIG. 14, the pressure increase time T _STA is the change output value pMCSTA.
The larger is, the shorter is set. In step 126, control for repeating the assist pressure increasing state shown in FIG. 2 and the assist pressure maintaining state shown in FIG. 3 at a predetermined duty ratio Duty1 (hereinafter referred to as Duty pressure increasing control) is started. When the processing of step 126 is executed, thereafter, the wheel cylinder pressure P _{W / C} of each wheel starts to increase with a predetermined pressure increase gradient.

In step 128, the above step 126
After the processing of is executed, the pressure increasing time T _STAWhether or not
Is determined. The process of this step 128 is the pressure increasing time.
T_{ST A}Is repeatedly executed until it is determined that
It As a result, the pressure increase time T_STAIs determined to have elapsed
In this case, the process of step 130 is performed next. Ste
In step 130, the Duty started in step 126 above
The pressure increase control is ended. The processing of this step 130 is executed
The wheel cylinder pressure P_{W / C}Boosting is stopped
It After the above process is completed, the process shown in FIG.
Other processing is executed.

According to the above process, after the execution of the start pressure increasing mode is requested, Du is performed for a predetermined pressure increasing time T _STA.
ty The wheel cylinder pressure P _{W / C}
The pressure can be increased. In the system of the present embodiment, the pumps 100 and 102 have output values pMCST at the time of change.
The larger A is, the higher the ejection performance is during the execution of the start boosting mode. Therefore, in order to generate the constant assist pressure Pa by executing the start pressure increasing mode, it is necessary to shorten the pressure increasing time T _{ST A} as the changing output value pMCSTA increases.

In this embodiment, the map shown in FIG. 14 is set such that the pressure increasing time T _STA becomes shorter as the changing output value pMCSTA becomes larger, as described above. Further, in the map shown in FIG. 14, the pressure increasing time T _STA is
It is set so that the changes appearing in the discharge characteristics of the pumps 100 and 102 can be appropriately offset. Therefore,
According to the braking force control device of the present embodiment, by executing the start pressure increasing mode, it is possible to always generate a constant assist pressure Pa without being influenced by the master cylinder pressure P _{M / C.}

FIG. 15 shows a flowchart of part of the main routine executed by the ECU 10. The ECU 10
By executing the series of processes shown in FIG. 15, when the execution of the (II) assist pressure increasing mode is requested, the wheel cylinder pressure P _{W /} is not affected by the master cylinder pressure P _{M / C. C} is always increased with a constant increasing tendency. The series of processing shown in FIG. 15 is executed under the condition that the BA control execution condition is satisfied. The series of processes shown in FIG. 15 starts from step 132.

At step 132, it is judged if the assist pressure increasing mode is requested. As described above, the assist pressure increasing mode is required when the driver performs a brake operation intended to rapidly increase the braking force. If it is determined that the assist pressure increasing mode is required as a result of the above determination, then step 134 is performed.
The process of is executed.

At step 134, the output signal pMC output from the hydraulic pressure sensor 29 at that time is fetched. In step 136, the duty ratio Duty2 used during execution of the assist pressure increasing mode is calculated. In step 136, the duty ratio Duty2 is calculated based on the output signal pMC.

FIG. 16 shows an example of a map defining the relationship between the duty ratio Duty2 and the output signal pMC. ECU1
In step 136, the duty ratio Duty2 is calculated according to the map shown in FIG. According to the map shown in FIG. 16, the duty ratio Duty2 is set to a smaller value as the output signal pMC is larger, that is, as the master cylinder pressure P _{M / C} is higher.

At step 138, the duty ratio Duty2
Then, the control for repeating the assist pressure increasing state shown in FIG. 2 and the assist pressure maintaining state shown in FIG. 3, that is, the duty increasing control using the duty ratio Duty2 is started.
Note that Duty2 is the ratio of the time during which the braking force control device is in the assist pressure increasing state to one cycle. When the processing of this step 138 is executed, the wheel cylinder pressure P _{W / C} of each wheel starts to increase at a predetermined pressure increase gradient. When the above processing is completed, other processing not shown in FIG. 13 is executed thereafter.

In the main routine of this embodiment, if it is determined in step 132 that the assist pressure increasing mode is not requested, then the processing of step 140 is executed. In step 140, the Duty pressure increase control started in step 138 is ended. This step 140
When the process of is executed, the increase of the wheel cylinder pressure P _{W / C} is stopped. When the above process is completed, the process shown in FIG.
Other processing not shown in is executed.

According to the above process, the wheel cylinder pressure P is increased by executing the duty boosting control using the duty ratio Duty2 only when the assist pressure boosting mode is required.
_{W / C} pressure can be increased. In the system of the present embodiment, the pumps 100 and 102 exhibit higher discharge performance during execution of the assist pressure increasing mode as the output signal pMC increases. Therefore, in order to obtain a constant pressure increase gradient during execution of the assist pressure increasing mode, it is necessary to reduce the duty ratio Duty2 as the output signal pMC increases.

In the present embodiment, the map shown in FIG. 16 is set so that the duty ratio Duty2 becomes shorter as the output signal pMC becomes larger, as described above. Further, in the map shown in FIG. 16, the duty ratio Duty2 is set so that the changes appearing in the discharge characteristics of the pumps 100 and 102 can be appropriately offset. Therefore, according to the braking force control apparatus of the present embodiment, the wheel cylinder pressure P _{W is} always maintained at a constant pressure increasing gradient without being influenced by the master cylinder pressure P _{M / C} during execution of the assist pressure increasing mode. _{/ C}
Can be increased.

FIG. 17 is a flowchart showing a part of the main routine executed by the ECU 10. The ECU 10
By executing the series of processes shown in FIG. 17, when the (V) assist pressure moderate increase mode is requested, the wheel cylinder pressure P _{W /} is not affected by the master cylinder pressure P _{M / C. C} is always increased stepwise by a fixed value. The series of processes shown in FIG. 17 is executed under the condition that the BA control execution condition is satisfied. The series of processes shown in FIG. 17 starts from step 142.

At step 142, it is judged if the assist pressure moderate increase mode is requested. As described above, the assist pressure moderate increase mode is required when the driver performs a braking operation intended to gently increase the braking force. As a result of the above determination, if it is determined that the assist pressure moderately increasing mode is requested, then step 14 is performed.
The process 4 is executed. On the other hand, if it is determined that the assist pressure moderate increase mode is not requested, then other processing not shown in FIG. 17 is executed.

At step 144, the output signal pMC output from the hydraulic pressure sensor 29 at that time is fetched. In step 146, when the assist pressure gentle increase mode is requested, the time T _MODE2 for maintaining the braking force control device in the assist pressure increase state is calculated. This step 14
6, the predetermined time T _MODE2 is calculated based on the output signal pMC.

FIG. 18 shows the predetermined time T _MODE2 and the output signal p.
An example of the map which defined the relationship with MC is shown. ECU 10
Calculates the predetermined time T _MODE2 in step 146 according to the map shown in FIG. According to the map shown in FIG. 18, the predetermined time T _MODE2 is set to be shorter as the output signal pMC is larger, that is, as the master cylinder pressure P _{M / C} is higher.

At step 148, the braking force control device is turned on.
The process for setting the assist pressure increasing state shown in FIG. 2 is executed.
It When the processing of this step 148 is executed,
Wheel cylinder pressure P_{W / C}Starts increasing pressure with a predetermined pressure increasing gradient
It In step 150, the process of step 148 is executed.
After execution, a predetermined time T _MODE2Whether or not has passed
Be separated. The process of step 148 is performed for a predetermined time T
_MODE2Is repeatedly executed until it is determined that
It As a result, the predetermined time T _MODE2Is determined to have elapsed
Then, the process of step 152 is executed next.

At step 152, a process for bringing the braking force control device into the assist pressure holding state shown in FIG. 3 is executed. When the process of step 152 is executed, the increase of the wheel cylinder pressure P _{W / C} is stopped. When the above processing is completed, other processing not shown in FIG. 17 is executed thereafter. According to the above process, when the assist pressure moderate increase mode is requested, the wheel cylinder pressure P _{W / C} can be increased stepwise only for a predetermined short time T _MODE2 . In the system of the present embodiment, the pumps 100 and 102 exhibit higher discharge performance during execution of the assist pressure increasing mode as the output signal pMC increases. Therefore, in order to increase the wheel cylinder pressure P _{W / C} by a constant value in the assist pressure moderate increase mode, it is necessary to shorten the predetermined time T _MODE2 as the output signal pMC increases.

In the present embodiment, the map shown in FIG. 18 is set such that the predetermined time T _MODE2 becomes shorter as the output signal pMC becomes larger, as described above. Furthermore, FIG.
In the map shown in FIG. 8, the predetermined time T _MODE2 is set so that the change appearing in the discharge characteristics of the pumps 100 and 102 can be appropriately offset. Therefore, according to the braking force control apparatus of the present embodiment, by executing the assist pressure gradual increase mode, the wheel cylinder pressure P _{W / C is} always a fixed value without being influenced by the master cylinder pressure P _{M / C.} Can be increased.

As described above, according to the braking force control apparatus of the present embodiment, (I) the start pressure boosting is performed even though the discharge capacity of the pumps 100 and 102 changes according to the master cylinder pressure P _{M / C.} It is possible to constantly generate a constant assist pressure Pa depending on the mode, and it is possible to constantly increase the wheel cylinder pressure P _{W / C} with a constant pressure increase gradient during execution of the (II) assist pressure increasing mode. , (V) The assist cylinder pressure increasing mode can always increase the wheel cylinder pressure P _{W / C} by a constant value. Therefore, according to the braking force control device of the present embodiment, it is possible to generate the braking force with stable characteristics during execution of the BA control.

By the way, in the above embodiment, (I)
In order to make the assist pressure Pa generated in the start pressure increasing mode always a constant value, the pressure increasing time T _STA is changed according to the master cylinder pressure P _{M / C} , but the assist pressure Pa is a constant value. The method is not limited to this. That is, the assist pressure Pa can be set to a constant value by changing the duty ratio Duty1 used during execution of the start pressure increasing mode based on the output signal pMC, for example. Further, the assist pressure Pa is equal to the pump 1
00 and 102 may be variable displacement pumps, and the pump displacement may be changed according to the master cylinder pressure P _{M / C} to obtain a constant value.

Further, in the above embodiment, in order to always obtain a constant pressure increasing gradient during execution of the (II) assist pressure increasing mode, the duty ratio is changed according to the master cylinder pressure P _{M / C.}
The duty 2 is changed, but the method for obtaining a constant pressure increase gradient is not limited to this. Similarly, in the above-described embodiment, in order to always increase the wheel cylinder pressure P _{W / C} by a constant value in the (V) assist pressure moderate increase mode, the predetermined time T is increased according to the master cylinder pressure P _{M / C. Although the MODE2} is changed, the method for obtaining a constant boost is not limited to this. The constant pressure increase gradient and the constant pressure increase amount described above can also be obtained, for example, by configuring the pumps 100 and 102 with variable displacement pumps and changing the pump displacement according to the master cylinder pressure P _{M / C.} You can

Further, although the above-mentioned embodiment is intended to obtain a stable pressure increasing characteristic during execution of the BA control, the application of the present invention is not limited to the combination with the BA control, and the pump is not limited thereto. With wheel hydraulic pressure P
It can be widely applied to brake fluid pressure control for increasing _{W / C.} In the above embodiment, the ECU 1
0 is the above steps 122, 124, 134, 136,
A common part of the "pressure increasing condition changing means" according to claim 1 to 3 by executing the processing of 144 and 146.
Minutes have been realized.

Further, in the above embodiment, the ECU 1
0 is the above steps 122, 124, 134 and 136.
By executing the processing of ( 1 ), the "pressure increasing condition changing means" according to claim 1 is realized .

In the above embodiment, SRC _-1
32 and SRC _-2 36 correspond to the "intake control valve" according to claim 2 , and the ECU 10 realizes the assist pressure increasing state so that the "pressure increasing control means" according to claim 2 is achieved. However, the above steps 122, 124, 134,
By executing the processing of 136, 144, 146, the "pressure increasing condition changing means" according to claim 2 is realized.

[0105]

As described above, according to the first to third aspects of the present invention, during execution of the brake fluid pressure control, the wheel cylinder pressure is always kept constant without being influenced by the master cylinder pressure. The pressure can be increased .

[0106]

[Brief description of drawings]

FIG. 1 is a system configuration diagram of a braking force control device that is an embodiment of the present invention.

FIG. 2 is a diagram showing an assist pressure increasing state of the braking force control device shown in FIG.

FIG. 3 is a diagram showing an assist pressure holding state of the braking force control device shown in FIG. 1.

FIG. 4 is a diagram showing an assist pressure reducing state of the braking force control device shown in FIG. 1.

5 is a diagram showing changes that occur in master cylinder pressure P _{M / C} and wheel cylinder pressure P _{W / C} when an emergency braking operation is performed in the braking force control device shown in FIG.

FIG. 6 is a table showing a control mode executed next to the start pressure increasing mode when BA control is executed in the braking force control device shown in FIG. 1.

FIG. 7 is a table showing a control mode executed next to the assist pressure increasing mode when BA control is executed in the braking force control device shown in FIG. 1.

FIG. 8 is a table showing a control mode executed subsequently to the assist pressure reduction mode when BA control is executed in the braking force control device shown in FIG. 1.

9 is a table showing a control mode executed next to the assist pressure holding mode when BA control is executed in the braking force control device shown in FIG. 1.

FIG. 10 is a table showing a control mode executed subsequently to the assist pressure gentle increase mode when BA control is executed in the braking force control device shown in FIG. 1.

11 is a table showing a control mode executed subsequently to the assist pressure gradual decrease mode when BA control is executed in the braking force control apparatus shown in FIG.

FIG. 12 is a diagram showing a relationship between a discharge capacity of a pump included in the braking force control device shown in FIG. 1 and a master cylinder pressure P _{M / C.}

FIG. 13 is a flowchart showing a series of processes executed when a start pressure increasing mode is requested in an embodiment of the present invention.

14 is an example of a map referred to in the series of processes shown in FIG.

FIG. 15 is a flowchart showing a series of processes executed when an assist pressure increasing mode is requested in one embodiment of the present invention.

16 is an example of a map referred to in the series of processes shown in FIG.

FIG. 17 is a flowchart showing a series of processes executed when the assist pressure moderately increasing mode is requested in the embodiment of the present invention.

18 is an example of a map referred to in the series of processes shown in FIG.

[Explanation of symbols]

10 Electronic Control Unit (ECU) 12 Brake Pedal 18 Master Cylinder 26 First Hydraulic Pressure Passage 28 Second Hydraulic Pressure Passage 29 Hydraulic Pressure Sensor 70, 72, 74, 76 Wheel Cylinder 100, 102 Pump P _{M / C} Master Cylinder Pressure pMC Output signal ΔpMC Change rate

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideyuki Aizawa 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Co., Ltd. (72) Inventor Masahiro Hara 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Co., Ltd. ( 56) References JP-A-8-20322 (JP, A) JP-A-9-164930 (JP, A) JP-A-5-97022 (JP, A) JP-A-9-24818 (JP, A) (58) ) Fields surveyed (Int.Cl. ⁷ , DB name) B60T 8/00 B60T 8/32-8/96 B60T ⁷ /12-7/22

Claims (3)

(57) [Claims] 1. A master cylinder and a wheel cylinder are connected to each other.
Pump that draws in brake fluid from the hydraulic passage
And a brake flap discharged from the pump.
Supply the wheel cylinder to the wheel cylinder to increase the wheel cylinder pressure.
To control the braking force control device that executes the brake fluid pressure control
Be careful Supply the brake fluid from the pump to the wheel cylinder.
Change the boosting condition when supplying according to the master cylinder pressure
Equipped with pressure increasing condition changing means, When the master cylinder pressure is lower, the pressure increasing condition changing means is
Increase pressure boosting time A braking force control device characterized by the above. 2.Connect the master cylinder and wheel cylinder
Pump that draws in brake fluid from the hydraulic passage
And a brake flap discharged from the pump.
Supply the wheel cylinder to the wheel cylinder to increase the wheel cylinder pressure.
Control brake fluid pressure controlFor braking force control device
Be carefulSupply the brake fluid from the pump to the wheel cylinder.
Change the boosting condition when supplying according to the master cylinder pressure
Pressure increasing condition changing means, Suction control provided between the hydraulic passage and the pump
Valve and When the wheel cylinder pressure is required to be increased, the pump
The intake control valve and the intake control valve are opened.
And a pressure increasing control means for executing the pressure increasing control
To When the master cylinder pressure is lower, the pressure increasing condition changing means is
When the intake control valve is opened during execution of the pressure increase control
Lengthen the time A braking force control device characterized by the above. 3.Connect the master cylinder and wheel cylinder
Pump that draws in brake fluid from the hydraulic passage
And a brake flap discharged from the pump.
Supply the wheel cylinder to the wheel cylinder to increase the wheel cylinder pressure.
Control brake fluid pressure controlFor braking force control device
Be carefulSupply the brake fluid from the pump to the wheel cylinder.
Change the boosting condition when supplying according to the master cylinder pressure
Equipped with pressure increasing condition changing means, The pump is a variable displacement pump, If the master cylinder pressure is low,
How to improve the discharge capacity of the pump A system characterized by
Power control device.