JPH10244921A - Braking force control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reflect the brake operation to be executed after the braking oil pressure has been increased, to the braking oil pressure, in a braking-force control device for producing a larger braking force as compared with the ordinary time when an emergency braking operation is carried out. SOLUTION: A hydraulic circuit for realizing an assist pressure increasing condition, an assist pressure maintaining condition, and an assist pressure decreasing condition is provided, in which the braking oil pressure is increased, maintained, or decreased independently of the brake operation. After an emergency brake operation has been detected, the assist pressure increasing condition is realized for a prescribed period for contriving the increase in the braking oil pressure [Period (3)]. When a master cylinder pressure PM/ C is maintained, the assist pressure maintaining condition is realized [Periods (4) and (8)]. When the PM/ C, is increased, the assist pressure increasing condition is realized [Period (7)]. When the PM/ C is decreased, the assist pressure decreasing condition is realized [Periods (5) and (9)].

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 that generates a larger braking force than usual when an emergency braking operation is performed on a vehicle.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Laid-Open No.
As disclosed in Japanese Patent No. 0, there is known a braking force control device that increases a braking oil pressure supplied to a wheel cylinder to a predetermined maximum oil pressure when a brake pedal is depressed at a speed exceeding a predetermined speed. The driver of the vehicle operates the brake pedal at a high speed to increase the braking force quickly. According to the above-described conventional braking force control device, when such a braking operation (hereinafter, referred to as an emergency braking operation) is performed, it is possible to generate a braking hydraulic pressure with a larger boosting ratio than normal. Hereinafter, the control for realizing the above functions is referred to as brake assist control (BA control).
Therefore, according to the above-described conventional braking force control device, when an emergency braking operation is performed by the driver, it is possible to appropriately generate the braking force that meets the driver's request.

[0003]

However, in the above-described conventional braking force control device, the braking oil pressure supplied to the wheel cylinder during the BA control is determined to be a predetermined maximum oil pressure. For this reason, depending on the conventional braking force control device, B
When the brake operation amount is increased or decreased after the start of the A control, the change cannot be reflected on the braking oil pressure, that is, the driver's intention cannot be reflected on the braking oil pressure.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and when a driver performs an emergency brake operation, a larger brake oil pressure is generated as compared with a normal operation.
It is an object of the present invention to provide a braking force control device capable of reflecting a driver's intention on the braking oil pressure.

[0005]

The above object is achieved by the present invention.
In the braking force control device that generates a larger braking oil pressure than usual when an emergency braking operation is performed by the driver, the assist pressure increasing state that increases the braking oil pressure regardless of the braking operation as described in And an assist pressure holding state for holding the brake oil pressure regardless of the brake operation;
A brake hydraulic pressure control mechanism for realizing an assist pressure reducing state for reducing the brake hydraulic pressure independently of the brake operation, an emergency brake operation detecting means for detecting execution of the emergency brake operation based on the state of the brake operation, and an emergency brake operation Is detected, the braking hydraulic pressure control mechanism is set to the assist pressure increasing state, a starting pressure increasing means for generating a larger braking oil pressure than usual, and the braking oil pressure is increased by the starting pressure increasing means. And a brake hydraulic pressure adjusting unit that switches between the assist pressure increasing state, the assist pressure holding state, and the assist pressure decreasing state according to a brake operation state to adjust a braking hydraulic pressure. Is achieved by

In the present invention, when an emergency braking operation is performed by the driver, the braking hydraulic pressure control mechanism is set to the assist pressure increasing state, so that a higher braking hydraulic pressure is generated as compared with normal operation. When the driver further performs a brake operation after the brake hydraulic pressure is set to be higher than normal, the state of the brake hydraulic control mechanism is appropriately switched according to the operation state. As a result, the brake oil pressure is increased or decreased in accordance with the brake operation while keeping the pressure higher than normal.

[0007] The object of the present invention is as described in claim 2.
2. The braking force control device according to claim 1, further comprising: a start operation amount detection unit that detects a brake operation amount when the state of the brake hydraulic control mechanism changes as a start operation amount, and the braking oil pressure adjustment unit. However, the present invention is also achieved by a braking force control device including first control state selecting means for selecting a state to be realized by the braking hydraulic control mechanism based on a deviation between an actual brake operation amount and the start operation amount. .

In the present invention, the state of the brake hydraulic pressure control mechanism is determined after the pressure increase of the brake hydraulic pressure by the start pressure increase means is completed.
The operation is appropriately switched so that the braking operation by the driver is reflected on the braking oil pressure. When the state of the brake hydraulic control mechanism is switched, the brake operation amount at that time is detected as the start operation amount. Thereafter, when the brake operation is further performed, a deviation equal to the brake operation amount executed after the state of the brake hydraulic control mechanism is switched is generated between the actual brake operation amount and the starting operation amount. The first control state selecting means detects, based on the deviation, a state of the brake operation further executed after the state of the brake hydraulic control mechanism is switched, and the state of the brake operation is reflected on the brake hydraulic pressure. Thus, the state to be realized by the brake hydraulic control mechanism is selected.

[0009] The object of the present invention is as described in claim 3.
2. The braking force control device according to claim 1, wherein said braking oil pressure adjusting means includes second control state selecting means for selecting a state to be realized by said braking oil pressure control mechanism based on a brake operation speed. This is also achieved by the device.

In the present invention, the state of the brake hydraulic pressure control mechanism is determined after the pressure increase of the brake hydraulic pressure by the start pressure increase means is completed.
The operation is appropriately switched so that the braking operation by the driver is reflected on the braking oil pressure. If the driver intends to increase the brake oil pressure, a positive brake operation speed occurs. Further, when the driver intends to decrease the braking oil pressure, a negative brake operation speed occurs. Further, when the driver intends to hold the braking oil pressure, the brake operation speed becomes a value near “0”. The second control state selecting means is configured to reflect the driver's intention on the braking oil pressure based on the brake operation speed,
The state to be realized by the brake hydraulic control mechanism is selected.

[0011] The above-mentioned object is as described in claim 4.
The braking force control device according to claim 1, wherein the amount of brake operation when the state of the braking hydraulic control mechanism changes is:
A starting operation amount detecting means for detecting as a starting operation amount; and the braking oil pressure adjusting means, based on a deviation between an actual brake operation amount and the starting operation amount and a brake operation speed, A third control state selecting means for selecting a state to be realized in a case where the absolute value of the deviation is equal to or more than a predetermined value and the absolute value of the brake operation speed is equal to or more than a predetermined speed; This is also achieved by a braking force control device including: a pressure-increase / decrease gradient changing unit that makes the pressure-increase / decrease gradient of the brake hydraulic pressure steeper than the above.

In the present invention, the state of the brake hydraulic pressure control mechanism is determined after the brake hydraulic pressure has been increased by the start pressure increasing means.
The operation is appropriately switched so that the braking operation by the driver is reflected on the braking oil pressure. The deviation between the actual brake operation amount and the start operation amount and the brake operation speed both reflect the driver's intention. The third control state selecting means, based on the deviation and the brake operation speed,
The state to be realized by the brake hydraulic pressure control mechanism is selected so that the driver's intention is reflected on the brake hydraulic pressure.

If the driver intends to increase or decrease the braking oil pressure with a steep gradient, a large deviation occurs between the actual brake operation amount and the start operation amount along with the brake operation, and a high speed Brake operation speed occurs. The pressure-increase / decrease gradient changing means determines that the driver intends to increase or decrease the braking oil pressure with a steep gradient from the above-described deviation and the brake operation speed. A state in which the braking oil pressure is increased or decreased by the gradient is realized. When the increase / decrease gradient of the brake hydraulic pressure is set as described above, the driver's intention is accurately reflected on the brake hydraulic pressure.

In the present invention, the increasing / decreasing gradient changing means changes the increasing / decreasing gradient of the brake hydraulic pressure, and includes a period during which the brake hydraulic pressure control mechanism realizes the assist pressure increasing state or the assist pressure decreasing state, and the assist pressure increasing state. The method of changing the duty ratio with the period for realizing the holding state, and the method of changing the increasing / decreasing gradient of the brake hydraulic pressure obtained when the assist pressure increasing state and the assist pressure decreasing state are realized by the brake hydraulic control mechanism. Both are included.

According to a fifth aspect of the present invention, in the braking force control apparatus according to the first aspect, the braking hydraulic pressure adjusting means terminates the increase of the braking hydraulic pressure by the starting pressure increasing means. Braking force control provided with fourth control state selecting means for selecting a state to be realized by the brake hydraulic control mechanism after the start based on the brake operation speed at the time when the increase of the brake hydraulic pressure by the start pressure increasing means is completed. This is also achieved by the device.

In the present invention, when a positive brake operation speed is generated at the time when the braking oil pressure by the start pressure increasing means is terminated, the driver intends to further increase the braking oil pressure at that time. Can be determined to be. Further, when a negative brake operation speed is generated at the time when the braking oil pressure by the start pressure increasing means is terminated, it can be determined at that time that the driver intends to decrease the braking oil pressure. Further, when a brake operation speed near “0” is generated at the time when the braking oil pressure by the start pressure increasing means ends,
At that point, it can be determined that the driver intends to maintain the braking hydraulic pressure. The fourth control state selecting means selects a state to be realized by the brake hydraulic control mechanism based on the brake operation speed at the time when the brake hydraulic pressure by the start pressure increasing means ends so that these intentions are reflected. .

[0017]

FIG. 1 shows a system configuration diagram of a hydro-booster type braking force control device (hereinafter simply referred to as a braking force control device) according to an embodiment of the present invention. The braking force control device according to the present embodiment includes an electronic control unit 10 (hereinafter, referred to as an electronic control unit 10).
ECU 10).

The braking force control device includes a brake pedal 12. A brake switch 14 is provided near the brake pedal 12. Brake switch 14
Outputs an ON signal when the brake pedal 12 is depressed. The output signal of the brake switch 14 is E
It is supplied to CU10. The ECU 10 determines whether or not the brake pedal 12 is depressed based on the output signal of the brake switch 14.

The brake pedal 12 is connected to the master cylinder 1
6. A reservoir tank 18 is disposed above the master cylinder 16. Reservoir tank 1
8, a return passage 20 for returning the brake fluid to the reservoir tank 18 is connected to the return passage. The supply passage 22 communicates with the reservoir tank 18. The supply passage 22 communicates with the suction side of the pump 24. The discharge side of the pump 24 has an accumulator passage 26
Are in communication. Accumulator passage 26 and supply passage 22
A constant pressure release valve 27 that opens when an excessive pressure is generated in the accumulator passage 26 is disposed between the accumulator passage 26 and the accumulator passage 26.

The accumulator passage 26 has a pump 24
Accumulator 28 for storing hydraulic pressure discharged from
Are in communication. In the accumulator passage 26,
Upper limit pressure switch 30 and lower limit pressure switch 32
Is connected. The upper limit pressure switch 30 is
The pressure in the accumulator passage 26 (hereinafter, accumulator pressure P
_ACCON) when the output exceeds the specified upper limit.
Occur. On the other hand, the lower limit pressure switch 32
Rator pressure P_ACCON output when exceeds the specified lower limit
Occurs.

The pump 24 operates after the ON output is issued from the lower limit pressure switch 32 until the ON output is issued by the upper limit pressure switch 30, that is, after the accumulator pressure P _ACC falls below the lower limit value. Until it reaches. Therefore, the accumulator pressure P _ACC is always maintained between the upper limit and the lower limit. A regulator 34 is integrated into the master cylinder 16. The accumulator passage 26 communicates with the regulator 34. Hereinafter, the master cylinder 16 and the regulator 34 are collectively referred to as a hide booster 36.

FIG. 2 is a sectional view of the hydro booster 36. The hydro booster 36 has a housing 38. A first piston 40 is provided inside the housing 38. The first piston 40 has a large-diameter portion 42 and a small-diameter portion 44. Inside the housing 38, an assist hydraulic chamber 46 is formed on the first piston 40 on the brake pedal 12 side, and an atmospheric pressure chamber 48 is formed around the small diameter portion 44. The atmospheric pressure chamber 48
It is always in communication with the reservoir tank 18.

A second piston 50 is provided inside the housing 38. The second piston 50 has a large diameter portion 5.
2 and a spool portion 54. Inside the housing 38, a first hydraulic chamber 56 is formed between the first piston 40 and the second piston 50, and a second hydraulic chamber 58 is formed so as to surround the spool 54. In the first hydraulic chamber 56, the first piston 40 and the second
A spring 60 for urging the piston 50 in the separating direction is provided. The second hydraulic chamber 58 communicates with the assist hydraulic chamber 46 via a hydraulic passage 62.

Inside the housing 38, a high-pressure passage 64 is formed, one end of which communicates with the accumulator passage 26 and the other end of which opens to the outer peripheral surface of the spool portion 54. The spool 54 is displaced leftward in FIG. 1 to make the high pressure passage 64 and the second hydraulic chamber 58 conductive, and is displaced rightward in FIG. The hydraulic chamber 58 is cut off.

A valve mechanism 66 is provided inside the housing 38. The valve mechanism 66 includes a valve seat 68, a valve body 70,
And a spring 72. An atmospheric pressure chamber 74 communicating with the reservoir tank 18 is formed around the valve seat 68. Further, a pressure regulating passage 76 communicating with the second hydraulic chamber 58 is opened at an end face of the valve seat 68. Valve seat 68
Is formed with an oil passage communicating the atmospheric pressure chamber 74 and the pressure regulating passage 76. The valve body 70 includes the second piston 50
Is the right displacement end in FIG. 1, that is, when the oil passage is in the conducting state when located at the original position, and the second piston 50 is displaced leftward from the original position in FIG. Then, the oil passage is closed.

Inside the housing 38, the reaction disk 7 is located at a position slightly separated from the end face of the valve mechanism 66.
8 are provided. The reaction disk 78 defines a reaction force chamber 80 communicating with the pressure adjustment passage 76 inside the housing 38. The reaction disk 78 is formed of a member having elasticity. When a high-pressure oil pressure is guided to the reaction force chamber 80, the reaction disk 78 is elastically deformed and comes into contact with the valve mechanism 66.

When the brake pedal force F is not applied to the brake pedal 12, the first piston 40 and the second piston 50 are both held at their original positions, that is, at the right displacement ends in FIG. In this case, since the pressure regulating passage 76 and the reservoir tank 18 are electrically connected via the valve mechanism 66, the second hydraulic chamber 58 is regulated to the atmospheric pressure. When the second hydraulic chamber 58 is adjusted to the atmospheric pressure, the assist hydraulic chamber 46 communicates with the second hydraulic chamber via the hydraulic passage 62, and is formed between the first piston 40 and the second piston 50. The first hydraulic chamber 56 is similarly adjusted to the atmospheric pressure.

When the brake pedal force F is applied to the brake pedal 12, the first piston 40 and the second piston 50
Are displaced from their original positions to the left in FIG. When a leftward displacement occurs in the second piston 50, the valve mechanism 66 is first closed, and the pressure regulating passage 76 and the reservoir tank 18 are shut off. When the second piston 50 is further displaced leftward, the high-pressure passage 64 and the second hydraulic chamber 58 are brought into conduction through the spool portion 54.

When the high-pressure passage 64 and the second hydraulic chamber 58 are brought into conduction, the accumulator pressure P _{AC C} is increased by the second hydraulic chamber 58.
Guided by the inner pressure of the second hydraulic chamber 58 (hereinafter, this pressure is referred to as a regulator pressure P _RE) by the boosts. The regulator pressure _PRE is guided to the assist hydraulic chamber 46. Therefore, when the regulator pressure P _RE is boosted, the first piston 40, the assist force Fa corresponding to the regulator pressure P _RE in addition to the brake pressing force F is applied.

[0030] regulator pressure P _RE guided to assist hydraulic chamber 46 is an area that acts on the first piston 40 and S _1, the assist force Fa can be expressed as the following equation. _{Fa = S 1 × P RE ···} (1) In this case, the first hydraulic chamber 56, hydraulic pressure corresponding to the brake pressing force F and the regulator pressure P _RE (hereinafter, this pressure master cylinder pressure P _{M / C} ) Occur. _Assuming that the cross-sectional area of the small diameter portion 44 of the first piston 40 is S ₂ , the master cylinder pressure P _{M / C} can be expressed by the following equation using the brake pedal force F and the regulator pressure _PRE .

P _{M / C} = (F + S ₁ × P _RE ) / S ₂ (2) At this time, the force F _{M / C at} which the brake fluid in the first hydraulic chamber 56 presses the second piston 58 is , the area of the large diameter portion 52 of the second piston 50 when the S _2, can be expressed as the following equation. F _{M / C} = P _{M / C} × S ₂ = F + S ₁ × P _PRE (3) Also, when the regulator pressure _PRE is generated in the second hydraulic chamber 58, the brake in the second hydraulic chamber 58 The force F _RE by which the fluid presses the second piston 58 can be expressed by the following equation, assuming that the area where the regulator pressure _PRE in the second hydraulic chamber 58 acts on the second piston 58 is S ₃ .

[0032] _{F RE = P RE × S 3} ··· (4) regulator pressure P _RE generated in the second hydraulic chamber 58 is also directed to the reaction chamber 80. The second piston 50 has a valve mechanism 66
And when the reaction disc 78 is displaced in the right in FIG. 2 until abutment, the second piston 50, the reaction force Fr in accordance with the regulator pressure P _RE through the reaction disc 78 is transmitted. The reaction force Fr can be expressed by the following equation using a predetermined value K.

Fr = K × P _RE (5) After the brake pedal force F is applied to the brake pedal 12,
F _{M / C} , F _RE , and F shown in the above equations (3) to (5)
The second piston 50 is displaced from the original position to the left in FIG. 2 while the following relationship is established for r. F _{M / C} > F _RE +
Fr ...
(6) In this case, since the second hydraulic chamber 58 is kept in conduction with the high-pressure passage 64, the regulator pressure _PRE gradually increases.

After the brake pedal force F is applied to the brake pedal 12, F _{M / C} shown in the above equations (3) to (5),
When a state is established in which the following relationship is established between F _RE and Fr, the second piston 50 is pushed back toward the original position. F _{M / C} <F _RE + Fr (7) When the second piston 50 is pushed back toward the original position, the second hydraulic chamber 58 is shut off from the high-pressure passage 64, so that the regulator pressure _PRE increases. Stopped. Thus, according to the hydro booster 36, after the brake pedal force is applied to the brake pedal 12, the regulator pressure _PRE is adjusted so that the following relationship is satisfied.

F _{M / C} = F _RE + Fr (8) The relation of the above equation (8) can be rewritten as the following equation using the relation of the above equations (3) to (5). P _RE = F / (S ₃ + K−S ₁ ) (9) In the present embodiment, the hydro booster 36 is determined such that “1 / (S ₃ + K−S ₁ )” in the above equation (9) is a predetermined value. The booster ratio is designed so that the regulator pressure _PRE and the master cylinder pressure PM _{/ C} are substantially equal. Therefore, according to the hydro booster 36, when the brake pedal force F is applied to the brake pedal 12, the brake pedal force F is applied to the first hydraulic chamber 56 and the second hydraulic chamber 58.
, A hydraulic pressure (master cylinder pressure PM _{/ C} and regulator pressure _PRE ) having a predetermined boosting ratio can be generated.

In the following description, the hydraulic pressure generated by the hydro booster 36, that is, the master cylinder pressure P _{M / C} generated in the first hydraulic chamber 56, and
Are collectively regulator pressure P _RE generated in the second hydraulic chamber 58, referred to as a master cylinder pressure P _{M / C.} As shown in FIG. 1, a first hydraulic chamber 56 of the hydro booster 36, and
A first hydraulic passage 82 and a second hydraulic passage 84 communicate with the second hydraulic chamber 58, respectively. First hydraulic passage 8
2 includes a first assist solenoid 86 (hereinafter referred to as SA _- 18).
6) and a second assist solenoid 88 (hereinafter, referred to as a second assist solenoid 88).
SA _- 288). On the other hand, the second hydraulic passage 84 has a third assist solenoid 90 (hereinafter referred to as SA).
_-3 90).

SA- ₁ 86 and SA- ₂₈₈ also include:
The control pressure passage 92 is in communication. The control pressure passage 92 is provided with a regulator switching solenoid 94 (hereinafter, STR94).
) To the accumulator passage 26. The STR 94 turns off the accumulator passage 26 and the control pressure passage 92 when turned off, and turns on the conduction when turned on.
Position solenoid valve.

The hydraulic pressure passage 96 provided corresponding to the right front wheel FR communicates with the SA _- 186. Similarly, SA- ₂
Reference numeral 88 denotes a hydraulic passage 9 provided corresponding to the left front wheel FL.
8 are in communication. The SA- ₁ 86 causes the first hydraulic passage 82 to be electrically connected to the first hydraulic passage 82 by being turned off.
And a two-position solenoid valve that realizes a second state in which the hydraulic pressure passage 96 is connected to the control pressure passage 92 by being turned on. Further, the SA- ₂ 88 realizes a first state in which the hydraulic pressure path 98 is connected to the first hydraulic pressure path 82 when turned off, and realizes a hydraulic pressure path 98 when turned on. Is a two-position solenoid valve that realizes a second state in which the valve is connected to the control pressure passage 92.

The hydraulic pressure passages 100 provided corresponding to the left and right rear wheels RL, RR communicate with the SA _- 390. SA
_-3 90 and a second fluid pressure passage 84 and the fluid pressure passage 100 by being turned off in a conductive state, and, in position solenoid valve which they and the cut-off state by being turned on is there. A check valve 102 is provided between the second hydraulic passage 84 and the hydraulic passage 100 to allow only the flow of fluid from the second hydraulic passage 84 toward the hydraulic passage 100.

In the hydraulic passage 96 corresponding to the right front wheel FR,
A right front wheel holding solenoid 104 (hereinafter, referred to as SFRH 104) communicates therewith. Similarly, a left front wheel holding solenoid 106 (hereinafter, referred to as a hydraulic passage 96) corresponding to the left front wheel FL
SFLH 106) is provided in the hydraulic passage 100 corresponding to the left and right rear wheels RL, RR.
(Hereinafter, referred to as SRRH 108) and a left rear wheel holding solenoid 110 (hereinafter, referred to as SRLH 110) communicate with each other. Hereinafter, when these solenoids are collectively referred to, they are referred to as “holding solenoid S ** H”.

A right front wheel pressure reducing solenoid 112 (hereinafter, referred to as SFRR 112) communicates with the SFRH 104. Similarly, SFLH 106, SRRH 108 and S
The RLH 110 includes a left front wheel decompression solenoid 11
4 (hereinafter, referred to as SFLR 114), a right rear wheel pressure reducing solenoid 116 (hereinafter, referred to as SRRR 116), and a left rear wheel pressure reducing solenoid 118 (hereinafter, referred to as SRLR 118) communicate with each other. Hereinafter, these solenoids are collectively referred to as “pressure reducing solenoid S ** R”.

The wheel cylinder 120 of the right front wheel FR communicates with the SFRH 104. Similarly, SFL
The wheel cylinder 122 of the left front wheel FL is attached to H106.
RRH 108 includes a wheel cylinder 124 of the right rear wheel RR.
However, the wheel cylinders 126 of the left rear wheel RL communicate with the SRLH 110, respectively. Further, the hydraulic passage 9
6 between the wheel cylinder 120 and the SFRH 104
From the wheel cylinder 120 side to the hydraulic passage 9
A check valve 128 is provided to allow fluid flow to 6. Similarly, between the hydraulic passage 98 and the wheel cylinder 122, between the hydraulic passage 100 and the wheel cylinder 124
And the hydraulic passage 100 and the wheel cylinder 12
6, between SFLH106 and SRRH10
Non-return valves 130, 132, 134 are provided to allow fluid flow to bypass SRLH 110 and SRLH 110.

The SFRH 104 is a two-position solenoid valve that brings the hydraulic passage 96 and the wheel cylinder 120 into conduction when turned off, and shuts them off when turned on. Similarly, SFLH
Each of 106, SRRH 108 and SRLH 110 is turned on to form a path connecting hydraulic passage 98 and wheel sinder 122, a path connecting hydraulic passage 100 and wheel sinder 124, and a path connecting hydraulic passage 100 and wheel sinder 124, and hydraulic path 100 and wheel sinter 126. This is a two-position solenoid valve that shuts off the connecting path.

SFRR112, SFLR114, SRR
A return passage 20 communicates with R116 and SRLR118. The SFRR 112 is a two-position solenoid valve that turns off the wheel cylinder 120 and the return passage 20 when turned off, and turns on the wheel cylinder 120 and the return passage 20 when turned on. It is. Similarly, SFLR114, S
RRR 116 and SRLR 118 are turned on, respectively, to connect wheel cylinder 122 to return passage 20, to connect wheel cylinder 124 to return passage 20, and to connect wheel cylinder 12 to return passage 20.
6 is a two-position solenoid valve for conducting a path connecting the return passage 6 and the return passage 20.

Near the front right wheel FR, a wheel speed sensor 13 is provided.
6 are provided. The wheel speed sensor 136 detects the right front wheel F
A pulse signal is output at a cycle corresponding to the rotation speed of R. Similarly, near the left front wheel FL, near the right rear wheel RR, and
Near the left rear wheel RL, a wheel speed sensor 1 that outputs a pulse signal at a cycle corresponding to the rotation speed of the corresponding wheel.
38, 140 and 142 are provided. Output signals of the wheel speed sensors 136 to 142 are supplied to the ECU 10. ECU10 detects the rotational speed V _W of each wheel based on the output signal of the wheel speed sensors 136-142.

A hydraulic pressure sensor 144 is provided in the second hydraulic passage 84 communicating with the second hydraulic chamber 58 of the hydro booster 36. The hydraulic pressure sensor 144 detects the hydraulic pressure generated inside the second hydraulic chamber 58, that is, the hydraulic booster 36.
And outputs an electric signal corresponding to the master cylinder pressure P _{M / C} generated. The output signal of the fluid pressure sensor 144 is EC
It is supplied to U10. The ECU 10 is a hydraulic pressure sensor 1
The master cylinder pressure P _{M / C} is detected based on the output signal of 44.

Next, the operation of the braking force control device of this embodiment will be described. The braking force control device according to the present embodiment switches the state of various solenoid valves disposed in the hydraulic circuit, thereby functioning as a normal brake device, functioning as an anti-lock brake system, and controlling braking force. When a quick rise is required, a function (brake assist function) of generating a larger braking force than in normal times is realized.

FIG. 1 shows a state of a braking force control device for realizing a function as a normal brake device (hereinafter, referred to as a normal brake function). That is, the normal braking function is realized by turning off all the solenoid valves included in the braking force control device as shown in FIG. Hereinafter, the state shown in FIG. 1 is referred to as a normal brake state. Also,
Control for realizing the normal brake function in the braking force control device is referred to as normal brake control.

In FIG. 1, the wheel cylinders 120 and 122 of the left and right front wheels FL and FR communicate with the first hydraulic chamber 56 of the hydro booster 34 via the first hydraulic passage 82. Further, the wheel cylinders 12 of the left and right rear wheels RL and RR are provided.
4 and 126 communicate with the second hydraulic chamber 58 of the hydro booster 36 via the second hydraulic passage 84. in this case,
Wheel cylinder pressure P of wheel cylinders 120 to 126
_{W / C} is always controlled to be equal to the master cylinder pressure PM _{/ C.} Therefore, according to the state shown in FIG. 1, the normal braking function is realized.

FIG. 3 shows a state of a braking force control device for realizing a function as an antilock brake system (hereinafter referred to as an ABS function). That is, ABS
The function is, as shown in FIG. 3, SA _- 186 and SA _- 288.
Is turned on, and the holding solenoid S ** H and the pressure reducing solenoid S ** R are appropriately driven in accordance with the request of the ABS. Hereinafter, the state shown in FIG. 3 is referred to as an ABS operation state. Further, control for realizing the ABS function in the braking force control device is referred to as ABS control.

The ECU 10 starts the ABS control when the vehicle is in a braking state and an excessive slip ratio is detected for any of the wheels. During the ABS control, the hydraulic passages 96 and 98 provided corresponding to the front wheels communicate with the second hydraulic chamber 58 of the hydro booster 36 in the same manner as the hydraulic passages 100 provided corresponding to the rear wheels. Therefore, ABS
During control, the wheel cylinder pressures P _{W / C of} all wheels are
The pressure is increased using the hydraulic chamber 58 as a hydraulic pressure source.

During the execution of the ABS control, the holding solenoid S
** H is opened and pressure reducing solenoid S ** R
Is closed, the wheel cylinder pressure P _{W / C of} each wheel
Can be increased. Hereinafter, this state is referred to as (i) pressure increase mode. Also, during the ABS control, 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.
Furthermore, when the holding solenoid S ** H is closed and the pressure reducing solenoid S ** R is opened during the ABS control, the wheel cylinder pressure P _{W / C} of each wheel can be reduced. Hereinafter, this state is referred to as (iii) decompression mode.

During the ABS control, the ECU 10 appropriately realizes (i) the pressure increasing mode, (ii) the holding mode, and (iii) the pressure reducing mode for each wheel according to the slip state of each wheel. Thus, the holding solenoid S ** H and the pressure reducing solenoid S ** R are controlled. Holding solenoid S **
When H and the pressure reducing solenoid S ** R are controlled as described above, the wheel cylinder pressures P _{W / C} of all the wheels are controlled to pressures that do not cause an excessive slip ratio on the corresponding wheels. Therefore, according to the above control, the ABS function can be realized in the braking force control device.

During the ABS control, the brake fluid in the wheel cylinders 120 to 126 is discharged to the return passage 20 every time the pressure reduction mode is performed on each wheel. Each time the pressure increase mode is performed on each wheel, the hydro booster 36
The brake fluid is supplied to the wheel cylinders 120 to 126 from. Therefore, during the ABS control, a larger amount of brake fluid flows out of the hydro booster 36 than during normal braking.

The hydraulic pressure source such as the accumulator 28 does not communicate with the first hydraulic chamber 56 of the Hyrod booster 36. Therefore, if the first hydraulic chamber 56 is used as a hydraulic pressure source during execution of the ABS control, a large amount of brake fluid flows out of the first hydraulic chamber 56, and as a result, an excessive stroke of the brake pedal 12 A situation arises. On the other hand, in the system according to the present embodiment, the second hydraulic chamber 58 that communicates with the accumulator 28 via the spool 54 during the ABS control is used as a hydraulic pressure source. Therefore, according to the system of the present embodiment, an excessive stroke does not occur on the brake pedal 12 during execution of the ABS control.

FIGS. 4 to 6 show states of the braking force control device for realizing the brake assist function (hereinafter referred to as the BA function). The ECU 10 performs the brake operation for requesting a quick rise of the braking force by the driver, that is, after the emergency brake operation is performed,
The BA function is realized by appropriately realizing the state shown in FIG.
Hereinafter, the control for realizing the BA function in the braking force control device is referred to as BA control.

FIG. 4 shows an assist pressure increasing state realized during the execution of the BA control. The assist pressure increase state is BA
This 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 this embodiment, the assist pressure increasing state is as shown in FIG.
SA- ₁ 86, SA- ₂ 88, SA- ₃ 90 and STR94
Is turned on.

In the assist pressure increasing state, all the wheel cylinders 120 to 126 communicate with the accumulator passage 26 via the STR 94. Therefore, when the assist pressure increasing state is realized, the wheel cylinder pressures P of all the wheels are increased.
_{The W / C} can be boosted using the accumulator 28 as a hydraulic pressure source. The accumulator 28 stores a high accumulator pressure P _ACC . Therefore, according to the assist pressure increasing state, the wheel cylinder pressures P of all the wheels are increased.
_{W / C} can be increased to a higher pressure than master cylinder pressure PM _{/ C.}

By the way, in the assist pressure increasing state shown in FIG. 4, the hydraulic pressure passages 96, 98, and 100 communicate with the accumulator passage 26 as described above, and the second hydraulic pressure passes through the check valve 102. It communicates with the passage 84. Therefore, the master cylinder pressure P guided to the second hydraulic pressure passage 84
If _{M / C} is greater than the wheel cylinder pressure P _{W / C} of each wheel can boost the wheel cylinder pressure P _{W / C} of the hydro-booster 36 even in the assist pressure increasing state as a fluid pressure source .

FIG. 5 shows an assist pressure holding state realized during execution of the BA control. The assist pressure holding state is BA
This is realized when it is necessary to maintain the wheel cylinder pressure P _{W / C} of each wheel during execution of the control. As shown in FIG. 5, the assist pressure holding state includes SA- ₁ 86, SA- ₂ 88, and SA- _3.
With the 90 and STR 94 turned on,
All holding solenoids S ** H are on (valve closed)
Is realized.

In the assist pressure holding state, the hydro booster 36 and the wheel cylinders 120 to 126 are shut off, and the return passage 20 and the wheel cylinders 120 to 12 are closed.
6 is shut off, and the flow of fluid from the accumulator 28 to the wheel cylinders 120 to 126 is blocked. 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. 6 shows a reduced assist pressure state realized during execution of the BA control. The assist pressure reduction state is BA
This is realized when it is necessary to reduce the wheel cylinder pressure P _{W / C} of each wheel during execution of the control. The assist pressure reduction state is realized by turning on the SA- ₁ 86 and the SA- ₂ 88 as shown in FIG. When the assist pressure is reduced, the accumulator 28 and the wheel cylinders 120 to 12
6 is shut off, the return passage 20 and the wheel cylinders 120 to 126 are shut off, and the hydraulic booster 36 and the wheel cylinders 120 to 126 are electrically connected. Therefore, according to the assist pressure reduction state, the wheel cylinder pressure P _{W / C} of all wheels can be reduced using the master cylinder pressure P _{M / C} as a lower limit.

FIG. 7 shows an example of a time chart realized when an emergency braking operation is performed by the driver in the braking force control device of the present embodiment. FIG. 7 (A)
The curve shown in the figure shows the master cylinder pressure PM _{/ C} per unit time when the driver performs an emergency brake operation.
An example of a change occurring in a change amount ΔP _{M / C} (hereinafter, referred to as a change speed ΔP _{M / C} ) of FIG. In addition, a curve shown by a broken line and a curve shown by a solid line in FIG. 7B show examples of changes occurring in the master cylinder pressure PM _{/ C} and the wheel cylinder pressure P _{W / C} under the same situation. In the system of the present embodiment, the master cylinder pressure P _{M / C} and its change speed ΔP _{M / C} are characteristic values of the operation amount of the brake pedal 12 and the operation speed of the brake pedal 12, respectively.

When the driver performs an emergency braking operation, the master cylinder pressure PM _{/ C} is immediately increased to an appropriate pressure after the braking operation is started, as indicated by a broken line in FIG. 7B. You. At this time, the master cylinder pressure P
Change rate [Delta] P M _{/ C} of the _{M / C,} as shown in FIG. 7 (A), towards the maximum value [Delta] P _MAX in synchronization with timing of the master cylinder pressure P _{M / C} after the braking operation is started to increase rapidly It increases and decreases to a value near “0” in synchronization with the timing when the master cylinder pressure P _{M / C} converges to an appropriate pressure.

As described above, the ECU 10 executes the BA control when the emergency braking operation by the driver is detected. In determining whether or not the driver has performed an emergency braking operation, the ECU 10 firstly operates the brake pedal 12 exceeding a predetermined speed, specifically, a change speed ΔP _M exceeding a first predetermined speed THΔP1. Detect _{/ C.} When detecting a change speed ΔP _{M / C} that satisfies ΔP _{M / C} > THΔP1, the ECU 10 determines that the emergency brake operation may have been performed, and shifts to the first standby state (FIG. 7B). Medium period).

After the shift to the first standby state, the ECU 10 sets a time t ₂ − until the change speed ΔP _{M / C} of the master cylinder pressure P _{M / C} becomes equal to or lower than the second predetermined speed THΔP2.
t ₁ = CSTANBY1 is counted. And ECU1
When the elapsed time CSTANBY1 is within a predetermined range, the CPU determines that the emergency braking operation has been performed by the driver and shifts to the second standby state (the middle period in FIG. 7B).

In the braking force control device of this embodiment, while the master cylinder pressure P _{M / C} is rapidly increasing, the master cylinder pressure P _{M / C} and the wheel cylinder pressure P _{W / C} are interposed. A large deviation Pdiff occurs. Under such circumstances, the wheel cylinder pressure P _{W / C} can be raised more quickly when the hydraulic booster 36 is used as the hydraulic pressure source than when the accumulator 28 is used as the hydraulic pressure source.

Therefore, after the emergency braking operation is performed by the driver and until the deviation Pdiff becomes a sufficiently small value, maintaining the normal brake control is faster than starting the BA control. The cylinder pressure P _{W / C} can be raised. For this reason, the ECU 10 starts the BA control when the deviation Pdiff becomes a sufficiently small value after the transition to the second standby state described above. When the BA control is started at such a timing, the wheel cylinder pressure P _{W / C} can be quickly and efficiently increased after the emergency braking operation is started.

In the braking force control device of the present embodiment, BA
When the control is started, first, (I) a start pressure increasing mode is executed (the middle period in FIG. 7B). (I) Start pressure increase mode
This is realized by maintaining the assist pressure increasing state shown in FIG. 4 during the predetermined pressure increasing time T _STA . As described above, according to the assist pressure increasing state, the wheel cylinder pressure P _{W / C of} each wheel is increased to a pressure exceeding the master cylinder pressure P _{M / C} using the accumulator 28 as a hydraulic pressure source. Therefore, when the BA control is started, (I) the wheel cylinder pressure P _{W / C of} each wheel is immediately increased to a pressure exceeding the master cylinder pressure P _{M / C} with execution of the start pressure increase mode. .
Hereinafter, a differential pressure generated between the wheel cylinder pressure P _{W / C} and the master cylinder pressure P _{M / C} during the execution of the BA control is referred to as an assist pressure Pa.

In this embodiment, the pressure increase time T _STA is calculated based on the maximum value ΔP _MAX of the change speed ΔP _{M / C} generated in the master cylinder pressure P _{M / C} during the emergency braking operation. Specifically, the pressure increase time T _STA is determined by the change rate ΔP
_The larger the maximum value ΔP _MAX of _{M / C} is, the longer the time is set,
The shorter the maximum value ΔP _MAX is, the shorter the time is set.

The maximum value ΔP _MAX of the change speed ΔP _{M / C} becomes a large value so that the driver intends to quickly start the braking force. Therefore, when the maximum value ΔP _MAX is a large value, after the BA control is started, it is appropriate to increase the wheel cylinder pressure P _{W / C} greatly in comparison with the master cylinder pressure P _{M / C.} . The pressure increase time T _STA is the maximum value Δ
When set as described above based on P _MAX , the wheel cylinder pressure P _{W / C} is reduced to the master cylinder pressure P _M after the emergency braking operation is detected so that the driver intends to quickly increase the braking force. Pressure increase compared to _{/ C} ,
That is, a large assist pressure Pa can be generated. Therefore, according to the braking force control device of the present embodiment,
(I) After the execution of the start pressure increase mode is started, the wheel cylinder pressure P _{W / C in} which the driver's intention is accurately reflected can be quickly generated.

In the braking force control device according to the present embodiment, (I)
After the start pressure increase mode ends, (II) assist pressure increase mode, (III) assist pressure decrease mode, (IV) assist pressure hold mode, (V)
Either the assist pressure gradual increase mode or (VI) the assist pressure gradual decrease mode is executed. If the master cylinder pressure P _{M / C} is rapidly increased during the execution of the BA control, it can be determined that the driver is requesting a larger braking force.
In this case, in the braking force control device of this embodiment, (II) the assist pressure increasing mode is executed (the middle period in FIG. 7B).
(II) The assist pressure increasing mode is realized by setting the braking force control device to the assist pressure increasing state, similarly to the above (I) start pressure increasing mode. According to the assist pressure increase state,
The wheel cylinder pressure P _{W / C} of each wheel is converted to the accumulator pressure P
_The pressure can be quickly raised toward _ACC . Therefore, according to the above processing, the intention of the driver can be accurately reflected on the wheel cylinder pressure P _{W / C.}

During execution of the BA control, the master cylinder pressure P
_{If the M / C} is rapidly reduced, it can be determined that the driver intends to rapidly reduce the braking force.
In this embodiment, in this case, (III) the assist pressure reduction mode is executed (the middle period in FIG. 7B). (III) The assist pressure reduction mode is realized by maintaining the assist pressure reduction state shown in FIG. According to the assist pressure reduction state, as described above, the wheel cylinder pressure P _{W / C of} each wheel is obtained.
Can be quickly reduced toward the master cylinder pressure PM _{/ C.} Therefore, according to the above processing, the intention of the driver can be accurately reflected on the wheel cylinder pressure P _{W / C.}

During execution of the BA control, the master cylinder pressure P
_{If M / C} is maintained at a substantially constant value, it can be determined that the driver intends to maintain the braking force. In this embodiment, in this case, (IV) the assist pressure holding mode is executed (the middle period in FIG. 7B). (IV) The assist pressure holding mode is realized by maintaining the assist pressure holding state shown in FIG. According to the assist pressure holding state, as described above, the wheel cylinder pressure P _{W / C of} each wheel
Can be maintained at a constant value. Therefore, according to the above processing, the driver's intention can be accurately determined by the wheel cylinder pressure P.
Can be reflected in _{W / C.}

During execution of the BA control, the master cylinder pressure P
_{If the M / C} is gradually increased, it can be determined that the driver intends to gradually increase the braking force. In this embodiment, in this case, (V) the assist pressure gradual increase mode (not shown) is executed. (V) The assist pressure gradual increase mode is realized by repeating the assist pressure increasing state shown in FIG. 4 and the assist pressure holding state shown in FIG. (V) According to the assist pressure gradual increase mode, the wheel cylinder pressure P _{W / C} of each wheel can be increased stepwise toward the accumulator pressure P _ACC . Therefore, according to the above processing, the driver's intention can be accurately determined by the wheel cylinder pressure P.
Can be reflected in _{W / C.}

During execution of the BA control, the master cylinder pressure P
_{When the M / C} is gradually reduced, it can be determined that the driver intends to gradually reduce the braking force. In this embodiment, in this case, (VI) the assist pressure gradual decrease mode is executed (the middle period in FIG. 7B). (VI) The assist pressure gradual decrease mode is realized by repeating the assist pressure decreasing state shown in FIG. 6 and the assist pressure holding state shown in FIG. (VI) According to the assist pressure gradual decrease mode, the wheel cylinder pressure P _{W / C} of each wheel is changed to the master cylinder pressure P
_The pressure can be reduced stepwise toward _{M / C.} Therefore, according to the above processing, the intention of the driver can be accurately reflected on the wheel cylinder pressure P _{W / C.}

According to the above-described processing, the assist pressure Pa accurately reflecting the driver's intention can be generated immediately after the driver performs the emergency braking operation. Therefore, according to the braking force control device of the present embodiment,
The rising tendency of the braking force can be changed according to the driver's intention. Further, according to the above processing, (I) after the assist pressure Pa is generated by the start pressure increase mode,
When a brake operation is performed by the driver, the wheel cylinder pressure P _{W / C} can be increased or decreased in accordance with the brake operation. Therefore, according to the above processing, B
During the execution of the A control, the driver's intention can be appropriately reflected on the wheel cylinder pressure P _{W / C} while maintaining the assist pressure Pa at a substantially constant value.

When the BA control is started in the braking force control device, the wheel cylinder pressure P _{W / C of} each wheel is rapidly increased thereafter, which may cause an excessive slip ratio for any one of the wheels. is there. In such a case, the ECU 10 executes the ABS control in addition to the BA control. Hereinafter, this control is referred to as BA + ABS control. BA
The + ABS control realizes any of the states shown in FIGS. 4 to 6 and a wheel having an excessive slip ratio (hereinafter referred to as a wheel).
ABS), the holding solenoid S ** H and the depressurizing solenoid S ** so that (i) the pressure increasing mode, (ii) the holding mode, and (iii) the depressurizing mode are realized as appropriate. This is realized by controlling R.

That is, when the assist pressure increasing state shown in FIG. 4 or the assist pressure holding state shown in FIG. 5 is realized, the accumulator pressure P _ACC is supplied to all the holding solenoids S ** H. Is done. In such a situation, by appropriately controlling the holding solenoid S ** H and the pressure reducing solenoid S ** R, (ii) the holding mode, (iii) the pressure reducing mode, and the wheel cylinder pressure for all the wheels. (I) The pressure increasing mode, which aims to increase P _{W / C} to a pressure exceeding the master cylinder pressure P _{M / C} , can be realized. Therefore, when either of the states shown in FIGS. 4 and 5 is realized, BA + ABS control is performed by controlling the holding solenoid S ** H and the pressure reducing solenoid S ** R in response to a request for ABS control. Can be realized.

When the assist pressure decreasing state shown in FIG. 6 is realized, the master cylinder pressure P _{M / C} is supplied to all the holding solenoids S ** H. In this case, (ii) the holding mode and (iii) the decompression mode can be realized for all the wheels. By the way, FIG.
Is reduced when the driver intends to reduce the braking force, that is, when it is not necessary to increase the wheel cylinder pressure P _{W / C of} any of the wheels. Therefore, if the (ii) holding mode and (iii) the depressurizing mode can be realized for the ABS target wheel while the assist pressure depressing state shown in FIG.
The requirement of A + ABS control can be satisfied.

As described above, according to the braking force control apparatus of the present embodiment, after the BA control is started, any one of the states shown in FIGS. Holding solenoid S ** H and pressure reducing solenoid S *
By controlling * R, BA + ABS control can be realized. According to the above BA + ABS control,
By using the accumulator 28 as a hydraulic pressure source, the wheel cylinder pressure P _{W / C} of all wheels can be controlled to an appropriate pressure that does not cause an excessive slip ratio on the corresponding wheels.

Next, with reference to FIGS. 8 to 24, the contents of processing executed by the ECU 10 to realize the above-described BA control will be described. FIG. 8 shows a flowchart of an example of a control routine executed by the ECU 10 in order to perform a condition determination for shifting to the first standby state and a condition determination for maintaining the first standby state. The routine shown in FIG. 8 is a periodic interruption routine that is started every predetermined time. When the routine shown in FIG. 8 is started,
First, the process of step 200 is executed.

In step 200, the flag XSTANB
It is determined whether or not Y1 is on. XSTAN
BY1 is a flag that is turned on when a condition for shifting to the first standby state is satisfied. Therefore, when the condition for shifting to the first standby state is not satisfied, it is determined that XSTANBY1 = ON is not satisfied. In this case, the process of step 202 is executed next.

In step 202, the first predetermined amount THP1 and the first predetermined speed THΔP are set according to the driving state of the vehicle.
1, and a noise cut value THNC are set. The first predetermined amount THP1, the first predetermined speed THΔP1, and the noise cut value THNC are threshold values used for determining a transition condition to the first standby state. That is, in the present embodiment, the condition for shifting to the first standby state is, as described later, the master cylinder pressure P _{M / C}
And the rate of change ΔP _{M / C} satisfies both conditions of PM _{/ C} ≧ THP1 and THΔP1 <ΔP _{M / C} <THNC.

In step 202, THP1,
THΔP1 and THNC are the vehicle speed SPD and the elapsed time T after the brake switch 14 is turned on.
Based on _STOP , it is set as shown in Table 1 below.

[0086]

[Table 1]

The first predetermined amount THP1 is shown in Table 1 above.
As described above, the vehicle speed SPD is equal to the predetermined speed V.₀If it is more than specified
The quantity THP1L is set. Also, the vehicle speed SPD is a predetermined speed.
Degree V ₀Is less than the predetermined amount THP1H
You. THP1L and THP1H are THP1L <TH
It is set so that the relationship of P1H is established. First
When the predetermined amount THP1 is set to the value shown in Table 1 above,
P which is one of the conditions for shifting to the one standby state_{M / C}≧ T
HP1 is easily established during high-speed running and at low-speed running.
It is difficult to be established.

When the vehicle is traveling at a low speed, it is less necessary to quickly increase the braking force than when the vehicle is traveling at a high speed. In addition, during low-speed running, deceleration during braking is more easily felt than during high-speed running. Therefore, it is appropriate that the BA control is less likely to be started when the vehicle is running at a low speed than when the vehicle is running at a high speed.
Such a request can be realized by setting the first predetermined amount THP1 to the value shown in Table 1 above.

The first predetermined speed THΔP1 is shown in Table 1 above.
As shown, the vehicle speed SPD is equal to the predetermined speed V. ₀That's all
First, the progress after the brake switch 14 is turned on.
Time T _STOPIs a predetermined time T₀If not reached the specified speed
The degree THΔP1H is set. Also, the vehicle speed SPD is
Speed V₀If not, set to the predetermined speed THΔP1M
Is done. THΔP1H and THΔP1M are THΔP
1H <THΔP1M.
I have. The first predetermined speed THΔP1 is set as described above.
Then, one of the conditions for shifting to the first standby state is T.
HΔP1 ≦ P_{M / C}Is easy to be established during high-speed driving, and
It is difficult to be established at low speeds.

When the vehicle is running at a low speed, the longitudinal acceleration G generated in the vehicle fluctuates greatly.
It is easy for the occupant of the vehicle to feel a large deceleration G. When the first predetermined speed THΔP1M is set as described above and it is difficult to satisfy the condition for shifting to the standby state at low speed, the occupant unnecessarily feels a large deceleration G by performing the BA control. Can be prevented.

As shown in Table 1, the first predetermined speed THΔP1 is a predetermined time T _STOP after the vehicle speed SPD is equal to or higher than the predetermined speed V ₀ and the elapsed time T _STOP after the brake switch 14 is turned on. When the time is equal to or longer than the time T _0, that is, when the time T ₀ has elapsed after the brake operation is started, the predetermined speed THΔP1L is set. T
HΔP1L is a smaller value than THΔP1M. When the first predetermined speed THΔP1 is set as described above, one of the conditions for shifting to the first standby state is TH.
ΔP1 ≦ P _{M / C} is more likely to be satisfied after T _STOP ≧ T ₀ than before.

In a vehicle, an emergency braking operation may be started at a point in time when a certain period of time has elapsed after the braking operation was started. In this case, since the brake pedal 12 is already depressed when the emergency brake operation is started, the change speed ΔP _{M / C} generated after the emergency brake operation is started is unlikely to be high. Therefore, in order to accurately detect such an emergency braking operation,
After a certain amount of time has elapsed from the start of the brake operation, the first predetermined speed THΔP1, which is a threshold value for determining the presence or absence of an emergency brake operation, may be set to a value smaller than the previous value. Is appropriate. First predetermined speed TH
By setting ΔP1 to the value shown in Table 1 above, such a request can be realized.

The noise cut value THNC is shown in Table 1 above.
As described above, the vehicle speed SPD is the predetermined speed V₀That is all, and
Elapsed time T after the brake operation was started_STOPAt a given time
Interval T ₀If not reached, set to the predetermined value THNCH
It is. When the vehicle speed SPD is equal to the predetermined speed V₀That's all
Elapsed time T_STOPIs a predetermined time T₀If it is more than
And the vehicle speed SPD is the predetermined speed V₀Prescribed if less than
The speed is set to THNCL. THNCH and THN
CL is set so that the relationship of THNCH> THNCL is satisfied.
Is set to

SPD ≧ V ₀ holds, and T _STOP ≧ T
_{If 0} is not established, as described above, a large change speed ΔP _{M / C} is generated with the emergency braking operation. Therefore,
In this case, it is appropriate to treat a relatively large change rate ΔP _{M / C} as effective data. On the other hand, if both SPD ≧ V ₀ and T _STOP ≧ T ₀ hold, and SP
When D <V ₀ holds, as described above, it is difficult for the change speed ΔP _{M / C to} become a large value with the emergency brake operation.
Therefore, in this case, it is appropriate to treat the relatively large change speed ΔP _{M / C} as an abnormal value. Noise cut value T
By setting the HNC to the value shown in Table 1 above, such a request can be realized.

By the above method, the first predetermined amount THP
After setting the first predetermined speed THΔP1 and the noise cut value THNC, the process of step 204 is executed. In step 204, it is determined whether or not the master cylinder pressure PM _{/ C} is equal to or greater than a first predetermined amount THP1. As a result, if it is determined that PM _{/ C} ≧ THP1 is not satisfied, it is determined that the condition for shifting to the first standby state is not satisfied, and the current routine is ended. On the other hand, if it is determined that PM _{/ C} ≧ THP1, the process of step 206 is performed.

In step 206, the change speed ΔP
_It is determined whether _{M / C} is larger than the first predetermined speed THΔP1 and smaller than the noise cut value THNC. As a result, THΔP1 <ΔP _{M / C} <THNC
Is not satisfied, it is determined that the condition for shifting to the first standby state is not satisfied, and the current routine is terminated. On the other hand, when it is determined that the above condition is satisfied, the process of step 208 is executed next.

In step 208, a flag XST is set to indicate that the condition for shifting to the first standby state has been satisfied.
ANBY1 is turned on. When the process of step 208 is completed, the current routine is completed. When this routine is started after the flag XSTANBY1 is turned on in step 208, it is determined that XSTANBY1 = ON is established in step 200. In this case, step 200 is followed by step 2
Ten processes are executed.

At step 210, the counter CSTAN
A process of incrementing BY1 is performed. The counter CSTANBY1 is a counter for counting an elapsed time after a condition for shifting to the first standby state is satisfied. The count time of the counter CSTANBY1 has been reset to "0" by initial processing when the vehicle is started. When the process of step 210 is completed, the process of step 212 is performed next.

At step 212, the counter CSTAN
It is determined whether or not the time counted by BY1 is equal to or less than the predetermined time α. The predetermined time α is a smaller value than the time during which the change speed ΔP _{M / C} is maintained at a large value when the emergency braking operation is performed. As a result of the above determination, C
If it is determined that STANBY1 ≦ α is satisfied, the process of step 214 is executed next.

In step 214, it is determined whether or not the change speed ΔP _{M / C} is lower than a predetermined value β. As a result, when ΔP _{M / C} <β is satisfied, it is determined that the change speed ΔP _{M / C} becomes a small value after a very short time after the condition for shifting to the first standby state is satisfied. it can. In this case, it is determined that the driver's brake operation was not an emergency brake operation, and the process of step 216 is executed.

In step 216, a process of turning off the flag XSTANBY1 to release the first standby state is executed. After the process of step 216 is performed, the process of step 218 is performed next. In step 218, a process of resetting the count time of the counter CSTANBY1 to “0” is executed. This step 2
When the process of 18 ends, the current routine ends.

In this routine, the above step 212
If it is determined that CSTANBY1 ≦ α is not established in step S214, and if it is determined that ΔP _{M / C} <β is not established in step 214, the condition for shifting to the first standby state is satisfied. Change rate ΔP during time
It can be determined that the phenomenon that the _{M / C} decreases to a small value has not occurred. In this case, the process of step 220 is executed next.

In step 220, the counter CSTAN
It is determined whether the count value of BY1 is equal to or longer than a second predetermined time THT2. The second predetermined time THT2 is a value that defines an upper limit value of the time for maintaining the first standby state after the condition for shifting to the first standby state is satisfied. Therefore, in this step 220, CSTANBY1 ≧ THT2
Is established, it can be determined that the duration of the first standby state has reached the upper limit. In this case, next, after the processing of steps 216 and 218 is executed, the current routine is terminated. On the other hand, if it is determined in this step 220 that CSTANBY1 ≧ TH2 is not satisfied, it can be determined that the duration of the first standby state has not yet reached the upper limit.
In this case, the process of step 222 is executed next.

At step 222, the flag XSTANB
It is determined whether or not Y2 is on. Flag XS
TANBY2 is the second routine in another routine described later.
This flag is turned on when it is determined that the condition for shifting to the standby state is satisfied. XSTANBY2
If it is determined that = ON is established, it is determined that it is not necessary to maintain the first standby state. In this case, next, after the processing of steps 216 and 218 is executed, the current routine is terminated. On the other hand, XSTAN
When it is determined that BY2 = ON is not established, it is determined that the first standby state needs to be maintained. In this case, the current routine is terminated without any further processing.

FIG. 9 is a flowchart showing an example of a control routine executed by the ECU 10 to determine a condition for shifting to the second standby state. The routine shown in FIG. 9 is a periodic interruption routine that is started every predetermined time. When the routine shown in FIG. 9 is started, first, the process of step 230 is executed. In step 230, the counting time of the counter CSTANBY1 is equal to the first time.
It is determined whether the elapsed time after the condition for shifting to the standby state is satisfied is equal to or longer than the first predetermined time THT1 and equal to or shorter than the second predetermined time THT2. Second
The predetermined time THT2 is the upper limit of the time during which the first standby state is to be maintained, as described above. On the other hand, when the emergency braking operation is performed, the first predetermined time THT1 is:
This is a value that determines the lower limit time during which the high-speed operation of the brake pedal 12 continues. Therefore, in the braking force control device of the present embodiment, after the brake operation is started, THT1 ≦ C
If the operation speed of the brake pedal 12 becomes a sufficiently small value before STANBY1 is established, it can be determined that the brake operation is not an emergency brake operation. In the above step 230, THT1 ≦ CSTA
If it is determined that NBY1 ≦ THT2 is not satisfied,
Thereafter, the current routine ends without any further processing. On the other hand, when it is determined that the above condition is satisfied, the process of step 232 is executed next.

In step 232, the rate of change ΔP is calculated from the previous processing cycle to the current processing cycle.
_It is determined whether the _{M / C} has changed from a speed exceeding the second predetermined speed THΔP2 to a speed equal to or lower than the second predetermined speed THΔP2. The second predetermined speed THΔP2 determines whether or not the master cylinder pressure P _{M / C} is rapidly increasing, that is,
This is a threshold value for determining whether or not the brake pedal 12 is operated at a high speed.

At the step 232, the change rate ΔP is changed from the time of the previous processing cycle to the time of the current processing cycle.
If it is determined that the _{M / C} has not changed from a speed exceeding THΔP2 to a speed equal to or less than THΔP2, it is necessary that the high-speed operation period of the brake pedal 12 has not ended from the previous processing cycle to the current processing cycle. You can judge. In this case, the current routine is terminated without any further processing.

On the other hand, if it is determined in step 232 that the change speed ΔP _{M / C} has changed from a speed exceeding THΔP2 to a speed equal to or lower than THΔP2 from the last processing cycle to the current processing cycle, It can be determined that the high-speed operation period of the brake pedal 12 has ended from the processing cycle of the above to the current processing cycle. In this case, the process of step 234 is executed next.

In step 234, the maximum value _{PM / CMAX of} the master cylinder pressure _{PM / C} detected after the condition for shifting to the first standby state is satisfied, and the master cylinder pressure immediately after the condition in step 232 is satisfied. The difference from pressure P _{M / C} "P
_It is determined whether or not “ _{M / CMAX−} P _{M / C} ” is smaller than the predetermined value γ. As a result, if it is determined that _{PM / CMAX−} P _{M / C} <γ holds, It can be determined that a large pedaling force F is being applied to the brake pedal 12. In this case, the process of step 236 is executed next, while the condition of step 234 is not satisfied. Can determine that the depression of the brake pedal 12 has already been loosened, in which case the current routine is terminated without proceeding with the process of shifting to the second standby state.

In step 236, a flag XST is set to indicate that the condition for shifting to the second standby state has been satisfied.
ANBY2 is turned on. When the process of step 236 ends, the current routine ends. FIG.
The ECU 1 determines the condition for starting the BA control and calculates the pressure increase time T _{SAT in} the start pressure increase mode.
0 shows a flowchart of an example of a control routine executed by the control routine 0. The routine shown in FIG. 10 is a periodic interruption routine that is started every predetermined time. When the routine shown in FIG. 10 is started, first, the process of step 240 is executed.

At step 240, the flag XSTANB
It is determined whether or not Y2 is on. as a result,
When it is determined that XSTANBY2 = ON is not established, it can be determined that it is not necessary to start the BA control. In this case, the current routine is terminated without any further processing. On the other hand, XSTANBY2
= ON is determined, then step 2
42 is executed.

In step 242, a reference pressure increase time T _STA0 which is a reference value of the pressure increase time T _STA is calculated. The reference pressure increase time T _STA0 is determined based on the operation speed of the brake pedal 12 generated in the process of the emergency brake operation with reference to the map stored in the ECU 10, and specifically, the transition to the first standby state. It is determined based on the maximum value ΔP _MAX of the change speed ΔP _{M / C} detected after the condition is satisfied.

FIG. 11 shows an example of the map referred to in step 242. In the present embodiment, the map of the reference pressure increase between T _STA0 is between the maximum change rate [Delta] P _MAX is too large reference pressure increase T _STA0 is set to be long. For this reason, the reference pressure increase time T _STA0 is set to be longer as a high operation speed of the brake pedal 12 occurs in the process of the emergency brake operation. When the above processing is completed, the processing of step 244 is next executed.

At step 244, it is determined whether or not the start timing of the BA control has arrived. As described above, in the present embodiment, in order to increase the wheel cylinder pressure P _{W / C} after the emergency braking operation is performed, it is preferable that the accumulator 28 be used as the hydraulic pressure source in order to increase the wheel cylinder pressure P _{W / C.} BA control is started when a more advantageous state is established, that is, when the deviation Pdiff between the master cylinder pressure P _{M / C} and the wheel cylinder pressure P _{W / C} becomes sufficiently small. In this step 244, it is determined whether or not the start timing has come. As a result, if it is determined that the start timing of the BA control has not arrived, the current routine is terminated without any further processing. On the other hand, if it is determined that the start timing of the BA control has come, the process of step 246 is executed next.

In step 246, the master cylinder pressure P
_{M / C} whether larger than the predetermined pressure P ₀ or not. After the BA control is started, the wheel cylinder pressure P _{W / C}
Is boosted using the accumulator 28 as a hydraulic pressure source. Wheel cylinder pressure P using accumulator 28 as a hydraulic pressure source
_The rate of change ΔP _{W / C} generated when increasing _{W / C} decreases as the differential pressure between wheel cylinder pressure P _{W / C} and accumulator pressure P _ACC decreases. Therefore, in order to generate the predetermined assist pressure Pa by executing the start pressure increase mode after the BA control is started, the higher the wheel cylinder pressure P _{W / C} at the start of the BA control, the higher the pressure. The pressure increase time T _STA needs to be long.

If it is determined in step 246 that P _{M / C} > P ₀ holds, it can be determined that a high wheel cylinder pressure P _{W / C} is generated at the start of the BA control.
In this case, the process of step 248 is performed next to increase the pressure increase time T _STA . On the other hand, P _{M / C} > P ₀
It is determined that the wheel cylinder pressure P _{W / C} at the start of the BA control is low. In this case, the process of step 250 is executed next to shorten the pressure increase time T _STA .

In step 248, step 242 is performed.
The pressure increasing time T _STA is calculated by the in computed reference pressure increase between T _STA0 multiplying the correction factor K _L. The correction coefficient K _L is a correction coefficient set in advance to set the long pressure increase time T _STA . In step 250, the pressure increase time T _STA is calculated by multiplying the reference pressure increase time T _STA0 calculated in step 242 by the correction count K _S. The correction coefficient K _S is a correction coefficient set in advance to set the short pressure increase time T _STA . Step 24 above
When the process of step 8 or the process of step 250 is completed, the process of step 252 is executed.

In step 252, the flag XSTANB
A process for turning off Y2 is executed, and a process for permitting the start of the BA control is executed. After the process of step 252 is performed, the BA control can be performed in the braking force control device thereafter. Step 25
When the processing of step 2 is completed, the current routine is terminated.

FIGS. 12 to 18 show a flowchart of an example of a control routine executed by the ECU 10 to realize the BA function in the braking force control device. This routine is a routine that is repeatedly started after the execution of the BA control is permitted in step 252. When this routine is started, first, the process of step 260 is executed.

In step 260, after the BA control is started, it is determined whether or not the (I) start pressure increasing mode has already been completed. As a result, if it is determined that the (I) start pressure increase mode has not been completed yet, the process of step 262 is executed. At step 262, the timer T _MODE
Is reset. The timer T _MODE is a timer that continuously counts up toward a predetermined upper limit value. In this routine, the timer T _MODE is used as a timer for counting the duration of each control mode for realizing the BA function. When the process of step 262 is completed, the process of step 264 is executed next.

In step 264, the braking force control device
The process for setting the assist pressure increasing state shown in FIG. 4 is executed. When the process of step 264 is performed,
Thereafter, the wheel cylinder pressure P _{W / C} of each wheel starts increasing at a predetermined rate using the accumulator 28 as a hydraulic pressure source.
Upon completion of the process in step 264, the process proceeds to step 2
Step 66 is executed.

In step 266, it is determined whether or not the count value of the timer T _MODE exceeds the pressure increase time T _STA calculated in step 248 or 250. As a result, when it is determined that T _MODE > T _STA does not hold,
The process of step 264 is executed again. According to the above process, after the BA control is started, the pressure increase time T _{ST A}
Until elapses, the braking force control device can be continuously maintained in the assist pressure increasing state. In the present embodiment, the processing of steps 260 to 266 realizes (I) the start pressure increasing mode.

As described above, the pressure increase time T _STA increases as the brake pedal 12 is operated at a higher speed in the course of the emergency brake operation, that is, as the emergency brake operation requires a quicker increase in the braking force. , Set for a long time. Further, the pressure increase time T _{ST A} is determined by taking into consideration (I) the pressure increase gradient of the wheel cylinder pressure P _{W / C} during the execution of the start pressure increase mode, and the master cylinder pressure P _W at the start of the BA control.
Corrected based on _{M / C.} Therefore, according to the braking force control device of the present embodiment, (I) by executing the start pressure increasing mode, it is possible to generate the assist pressure Pa that accurately reflects the driver's intention.

In this embodiment, (I) the driver's intention is reflected on the assist pressure Pa by appropriately setting the pressure increasing time T _STA in the start pressure increasing mode. The method of reflecting the driver's intention is not limited to this. Based on the brake operation speed generated during the emergency brake operation, (I) the wheel cylinder pressure P _{W /} The intention of the driver may be reflected on the assist pressure Pa by changing the pressure increasing gradient of _C.

In the braking force control device of this embodiment,
(I) When the pressure increase time T _STA elapses after the start pressure increase mode is started, it is determined in step 266 that T _MODE > T _STA is satisfied. In this case, (I) the process after step 268 is executed to end the start pressure increase mode and start another control mode. FIG. 19 is a table showing the control mode executed after (I) the start pressure increase mode in relation to the change speed ΔP _{M / C} at the end of the (I) start pressure increase mode (hereinafter, the start pressure increase mode). End time table). In the present embodiment, the control mode to be executed after the (I) start pressure increase mode is determined by the processing after step 268 so as to correspond to the start pressure increase end time table shown in FIG.

In step 268, (I) the change speed ΔP _{M / C} occurring in the master cylinder pressure P _{M / C} at the end of the start pressure increase mode is taken. In step 270, the change speed ΔP _{M / C} captured as described above is changed to a positive predetermined value ΔP
It is determined whether or not it exceeds ₁ . As a result, ΔP
If it is determined that _{M / C} > ΔP ₁ (> 0) holds,
It can be determined that the driver is required to increase the braking force. In this case, the control mode following the start pressure increasing mode is determined as (II) assist pressure increasing mode, and the process of step 272 is executed.

In step 272, the process for setting the braking force control device to the assist pressure increasing state shown in FIG. 4 is executed to start the (II) assist pressure increasing mode. After the process of step 272 is executed, the wheel cylinder pressure P _{W / C} of each wheel is immediately increased using the accumulator 28 as a hydraulic pressure source. When the process of step 272 ends, the process of step 274 is executed next.

In step 274, a process of turning on the flag XPAINC is executed to indicate that the currently executed control mode is (II) the assist pressure increasing mode. When the process of step 274 is completed, the current routine is completed. In step 270 above, ΔP
If it is determined that _{M / C} > ΔP ₁ does not hold, the process of step 276 is executed next.

In step 276, step 268 is performed.
It is determined whether or not the change speed ΔP _{M / C} fetched in the step ( _b) is lower than a predetermined negative value ΔP ₂ . As a result, ΔP _{M / C}
When it is determined that <ΔP ₂ (<0) holds, it can be determined that the driver is required to reduce the braking force. In this case, the control mode following the (I) start pressure increasing mode is determined to be (III) the assist pressure decreasing mode, and then the process of step 278 is executed.

In step 278, (III) the process of setting the braking force control device to the assist pressure reducing state shown in FIG. 6 is executed to start the assist pressure reducing mode. After the process of step 278 is performed, the wheel cylinder pressure P _{W / C} of each wheel is reduced with the master cylinder pressure P _{M / C} as the lower limit. When the process of step 278 is completed, the process of step 280 is executed next.

In step 280, a process of turning on the flag XPARED to indicate that the currently executed control mode is (III) the assist pressure reducing mode is executed. When the process of step 280 ends, the current routine ends. In step 276 above, ΔP
_When it is determined that _{M / C} <ΔP ₂ is not established, that is, when the start pressure increase mode ends, the change speed ΔP _{M / C}
Is determined to be maintained near "0", it can be determined that the driver is required to maintain the braking force. In this case, the process of step 282 is executed next.

In step 282, a process is performed to set the braking force control device to the assist pressure reduced state shown in FIG. 5 in order to start the (IV) assist pressure holding mode. After the process of step 282 is executed, the wheel cylinder pressure P _{W / C} of each wheel is maintained at a constant value without being increased or decreased. When the process of step 282 ends, the process of step 284 is executed.

In step 284, processing is performed to turn on the flag XPAHOLD to indicate that the currently executed control mode is the (IV) assist pressure holding mode. When the process of step 284 is finished, the current routine is finished. Steps 260 to 284 above
When this routine is started again after the execution of the processing of (1), it is determined in step 260 that the (I) start pressure increase mode has already been completed. In this case, step 26
Subsequent to 0, the process of step 286 is executed.

In step 286, the master cylinder pressure P _{M / C} occurring at that time and the rate of change Δ
A process for capturing PM _{/ C} is executed. This step 286
Is completed, the process of step 288 is executed. In step 288, the control mode currently executed in the braking force control device is determined. In this step 288, when the flag XPAINC is in the ON state, it is determined that the control mode currently being executed is (II) the assist pressure increasing mode. In this case, this step 288
Then, the process of step 290 shown in FIG. 13 is executed.

FIG. 20 is a graph showing the relationship between the control mode to be executed next and the change rate ΔP _{M / C} of the master cylinder pressure P _{M / C} when the control mode currently being executed is the assist pressure increasing mode. (Hereinafter, referred to as a pressure increase table). In the present embodiment, the processing after step 290 is performed so as to correspond to the pressure increasing table shown in FIG.
(II) The control mode to be executed after the assist pressure increasing mode is determined.

At step 290, the master cylinder pressure P
Whether change rate [Delta] P M _{/ C} to the _{M / C} exceeds a predetermined positive value [Delta] P ₃ has occurred is determined. As a result, ΔP _{M / C} > Δ
When it is determined that P ₃ (> 0) holds, it can be determined that the driver is required to increase the braking force. In this case, the process of step 292 is executed after step 290. On the other hand, if it is determined that the change speed ΔP _{M / C} that satisfies the above condition has not occurred,
It can be determined that the driver is required to maintain the braking force. In this case, the process of step 294 is executed after step 290.

In step 292, in order to enable the braking force to be further increased, the process for continuously requesting the execution of the (II) assist pressure increasing mode, that is, the (II) assist pressure increasing mode is set to the request mode. The processing is executed. Step 29
In step 4, (IV) a process of requesting execution of the assist pressure holding mode, that is, (IV) a process of setting the assist pressure holding mode to the request mode, is performed so that the braking force can be held. The processing of the above step 292 or this step 2
When the process of step 94 is completed, the process proceeds to step 3 shown in FIG.
42 is executed.

In this routine, step 288 is performed.
When it is determined that the flag XPARED is in the ON state, it is determined that the control mode currently being executed is (III) the assist pressure reduction mode. In this case, following step 288, the process of step 296 shown in FIG. 14 is executed. FIG. 21 shows that the currently executed control mode is (II
I) When the assist pressure reducing mode is selected, the control mode to be executed next is set to the changing speed ΔP of the master cylinder pressure P _{M / C.}
A table (hereinafter, referred to as a decompression table) expressed in relation to _{M / C} is shown. In the present embodiment, the control mode to be executed after the (III) assist pressure reduction mode is determined by the processing after step 296 so as to correspond to the pressure reduction table shown in FIG.

In step 296, the master cylinder pressure P
Whether change rate [Delta] P M _{/ C} below a predetermined negative value [Delta] P ₄ to _{M / C} has occurred is determined. As a result, ΔP _{M / C} <Δ
When it is determined that P ₄ (<0) holds, it can be determined that the driver is required to reduce the braking force. In this case, the process of step 298 is executed after step 296. On the other hand, if it is determined that the change speed ΔP _{M / C} that satisfies the above condition has not occurred,
It can be determined that the driver is required to maintain the braking force. In this case, the process of step 300 is executed after step 296.

In step 298, in order to further reduce the braking force, (III) the process of requesting the execution of the assist pressure reducing mode, that is, (III) the process of setting the assist pressure reducing mode to the request mode is performed. Be executed. In step 300, in order to enable the holding of the braking force, (IV) a process of requesting execution of the assist pressure holding mode, that is, (IV)
A process for setting the assist pressure holding mode to the request mode is executed. When the processing in step 298 or the processing in step 300 is completed, the processing in step 342 shown in FIG. 18 is performed thereafter.

In this routine, step 288 is performed.
If it is determined that the flag XPAHOLD is in the ON state, it is determined that the control mode currently being executed is the (IV) assist pressure holding mode. In this case, step 2
Subsequent to 88, the process of step 302 shown in FIG. 15 is executed. 22, when the control mode currently being executed is the assist pressure holding mode, the control mode to be executed next, the change rate ΔP of the master cylinder pressure P _{M / C
M / C} and master cylinder pressure P _{M / C} change amount “P _{M / C} −
A table (hereinafter, referred to as a holding table) expressed in relation to P _STA ”. In the present embodiment, the processing after step 302 is performed so that (IV) assist is performed so as to correspond to the holding table shown in FIG. The control mode to be executed after the pressure holding mode is determined, and the change amount “P” shown in FIG.
_{M / C-} P _STA ”is the current master cylinder pressure P _{M / C} ,
The master cylinder pressure P _{M / C} detected at the time the current control mode is started (hereinafter referred to as the starting master cylinder pressure P
_STA ), that is, a value corresponding to the amount of change in the master cylinder pressure PM _{/ C} after the current control mode is started.

At step 302, the master cylinder pressure P
_{M / C}Has a positive predetermined value ΔP_FiveChange rate ΔP exceeding_{M / C}Is raw
And a positive predetermined value P₁Change P exceeding_{M / C}
−P _STAIt is determined whether or not an error has occurred. as a result,
ΔP_{M / C}> ΔP_Five(> 0) holds, and P_{M / C}−P
_STA> P₁If (> 0) holds, hold the braking force.
The intended driver must be able to quickly increase the braking force.
It can be determined that the intention has been started. in this case,
Subsequent to the step 302, the processing of the step 304 is executed.
Is performed.

In step 304, (II) a process of requesting execution of the assist pressure increasing mode, that is, a process of setting the (II) assist pressure increasing mode to the request mode so that the braking force can be quickly raised. Is executed. When the process of step 304 ends, the process of step 342 shown in FIG. 18 is executed. On the other hand, step 302
If the above condition is not satisfied, it can be determined that the driver does not intend to quickly increase the braking force. In this case, the process of step 306 is performed next.

In step 306, the master cylinder pressure P
_{M / C}Negative value ΔP₆Change rate ΔP below_{M / C}Is raw
And a negative predetermined value P_FourLess than P_{M / C}
−P _STAIt is determined whether or not an error has occurred. as a result,
ΔP_{M / C}<ΔP₆(<0) holds, and P_{M / C}−P
_STA<P_FourIf (<0) holds, hold the braking force.
The intended driver must be able to reduce braking force quickly.
It can be determined that the intention has been started. in this case,
Subsequent to the step 306, the processing of the step 308 is executed.
Is performed.

At step 308, (III) a process for requesting execution of the assist pressure reducing mode, that is, (III) a process for setting the assist pressure reducing mode to the request mode is executed in order to quickly reduce the braking force. This step 308
Is completed, the process proceeds to step 342 shown in FIG.
Is performed. On the other hand, when the condition of step 306 is not satisfied, it can be determined that the driver does not intend to reduce the braking force quickly. In this case, the process of step 310 is performed next.

At step 310, it is determined whether or not the _count value of the timer T _MODE has reached a predetermined time T _MODE1 . The predetermined time T _MODE1 is equal to or greater than a predetermined value P ₁ or a predetermined value P _{M / C} −P _STA when the driver operates the brake pedal 12 with the intention of quickly changing the braking force. P ₄ is substantially equal to the upper limit value of the time required to becomes less. Therefore, when T _MODE ≧ T _{MODE 1} is not satisfied, even if neither the condition of the step 302 nor the condition of the step 306 is satisfied, the brake intended to promptly change the braking force is set. The possibility of operation cannot be denied. In this case, the process of step 312 is executed next.

In step 312, a process for requesting the execution of the (IV) assist pressure holding mode, that is, a process for setting the (IV) assist pressure holding mode to the request mode, is executed. When the process of step 312 is completed,
Is performed in step 342 shown in FIG. In a situation where neither the condition of the step 302 nor the condition of the 306 is satisfied, in the step 310, T _MODE ≧ T
_When it is determined that _MODE1 is established, it can be determined that the driver has not performed the brake operation intended to quickly change the braking force. In this case, the process of step 314 is executed following step 310.

In step 314, the master cylinder pressure P
_A change amount P _{M / C} −P _STA exceeding a positive predetermined value P ₂ is added to _{M / C.}
It is determined whether or not an error has occurred. As a result, P _{M / C} −
If P _{ST A>} P ₂ where (> 0) is satisfied, the driver had intended to hold the braking force, it can be determined that began intended to moderately increase the brake force. In this case, the process of step 316 is performed after step 314.

In step 316, in order to gradually increase the braking force, (V) processing for requesting execution of the assist pressure gradual increase mode, that is, (V) processing for setting the assist pressure gradual increase mode to the request mode, is executed. You. When the process of step 316 ends, the process of step 342 shown in FIG. 18 is next executed. On the other hand, when the condition of step 314 is not satisfied, it can be determined that the driver has not requested execution of the (V) assist pressure gradual increase mode. In this case, the process of step 318 is executed following step 314.

In step 318, the master cylinder pressure P
_The amount of change P _{M / C} −P _STA that falls below the negative predetermined value P ₃ is added to _{M / C.}
It is determined whether or not an error has occurred. As a result, P _{M / C} −
If P _{ST A} <P ₂ where (<0) is satisfied, the driver had intended to hold the braking force, it can be determined that the beginning intended to gently reduce the braking force. In this case, the process of step 320 is executed after step 318.

In step 320, in order to gradually reduce the braking force, a process for requesting the execution of the (VI) assist pressure gradual decrease mode, that is, a process for setting the (VI) assist pressure gradual decrease mode to the request mode is executed. You. When the process of step 320 ends, the process of step 342 shown in FIG. 18 is next executed. On the other hand, if the condition of step 318 is not satisfied, it is determined that the driver intends to maintain the braking force, that is, the driver has continuously requested execution of the (IV) assist pressure holding mode. it can. In this case, following step 318, step 3
Twelve processes are executed.

In this routine, step 288 is performed.
When it is determined that the flag XPASLINC is in the ON state, it is determined that the control mode currently being executed is (V) the assist pressure gradual increase mode. In this case, following step 288, the process of step 322 shown in FIG. 16 is executed. The flag XPASLINC is a flag that is turned on when the (V) assist pressure gradual increase mode is selected as the control mode, as described later.

[0153] Figure 23, when the control mode currently being executed is the assist pressure moderately increasing mode, the control mode to be executed next, the master cylinder pressure P _{M / C} change rate [Delta] P M _{/ C}
And the change amount P _{M / C} -P _{STA of} the master cylinder pressure P _{M / C}
(Hereinafter, referred to as a slowly increasing table). In this embodiment, the processing after step 322 is performed so as to correspond to the slowly increasing table shown in FIG.
(V) The control mode to be executed after the assist pressure gradual increase mode is determined.

At step 322, the master cylinder pressure P
_{M / C}Has a positive predetermined value ΔP₇Change rate ΔP exceeding_{M / C}Is raw
And a positive predetermined value P_FiveChange P exceeding_{M / C}
−P _STAIt is determined whether or not an error has occurred. as a result,
ΔP_{M / C}> ΔP₇(> 0) holds, and P_{M / C}−P
_STA> P_FiveIf (> 0) is satisfied, moderate the braking force
The driver intended to increase the braking force
To judge that they have begun to intend to increase
it can. In this case, following step 322, step
Step 324 is executed.

In step 324, (II) a process for requesting execution of the assist pressure increasing mode, that is, (II) a process for setting the assist pressure increasing mode to the request mode, in order to enable a rapid rise of the braking force. Is executed. When the process of step 324 is completed, the process of step 342 shown in FIG. 18 is executed. On the other hand, step 322
If the condition is not satisfied, it can be determined that the driver does not intend to increase the braking force quickly. In this case, the process of step 326 is executed next.

At step 326, it is determined whether or not the _count value of the timer T _MODE has reached a predetermined time T _MODE2 . In the braking force control device of this embodiment, (V) the assist pressure gradual increase mode is realized by repeating the assist pressure increasing state shown in FIG. 4 and the assist pressure holding state shown in FIG. The predetermined time T _MODE2 is a time that is set as a time for which the (V) assist pressure gradual increase mode is required to maintain the braking force control device in the assist pressure increasing state.

Therefore, in step 326, T _MODE ≧ T
If it is determined that _MODE2 is established, the period in which the braking force control device should be maintained in the assist pressure increasing state has ended, that is, the time has come when the braking force control device should be in the assist pressure holding state. Can be determined to be. In this case, following step 326, step 328
Is performed.

In step 328, a process for requesting execution of the (IV) assist pressure holding mode, that is, a process for setting the (IV) assist pressure holding mode to the request mode is executed. When the process of step 328 ends, the process of step 342 shown in FIG. 18 is next executed. On the other hand, if it is determined in step 326 that T _MODE ≧ T _MODE2 is not satisfied, it can be determined that the period in which the braking force control device should be maintained in the assist pressure increasing state has not ended. In this case, following step 326, step 330
Is performed.

In step 330, processing for requesting execution of the (V) assist pressure gradual increase mode, that is, processing for setting (V) the assist pressure gradual increase mode to the request mode, is executed. When the process of step 330 is completed, the process of step 342 shown in FIG. 18 is executed. According to the above-described process, if the condition for requesting the (II) assist pressure increasing mode (the condition of step 322) is not satisfied after the request for execution of the (V) assist pressure increasing mode is started, After maintaining the request for a predetermined period T _MODE2 , the request mode can be changed to (IV) the assist pressure holding mode.

In this routine, step 288 is performed.
When it is determined that the flag XPASLRED is in the ON state, it is determined that the control mode currently being executed is the (VI) assist pressure gradual decrease mode. In this case, following step 288, the process of step 332 shown in FIG. 17 is executed. The flag XPASLRED is a flag that is turned on when the (VI) assist pressure gradual decrease mode is selected as the control mode, as described later.

FIG. 24 shows that the control mode currently being executed is (VI)
In the case of the assist pressure moderating mode, the control mode to be executed next is set to the changing speed ΔP of the master cylinder pressure P _{M / C.
M / C} and change amount P _{M / C} -P of master cylinder pressure P _{M / C
4} shows a table (hereinafter, referred to as a slow-decreasing table) expressed in relation to the _STA . In the present embodiment, the control mode executed following the (VI) assist pressure gradual decrease mode is determined by the processing after step 332 so as to correspond to the gradual decrease table shown in FIG.

In step 332, the master cylinder pressure P
_{M / C}Negative value ΔP₈Change rate ΔP below_{M / C}Is raw
And a negative predetermined value P₆Less than P_{M / C}
−P _STAIt is determined whether or not an error has occurred. as a result,
ΔP_{M / C}<ΔP₈(<0) holds, and P_{M / C}−P
_STA<P₆If (<0) holds, reduce the braking force.
The driver intended to reduce the
To judge that it has begun to intentionally decrease
it can. In this case, step 332 is followed by step
Step 334 is performed.

In step 334, (III) a process for requesting execution of the assist pressure reducing mode, that is, (III) a process for setting the assist pressure reducing mode to the request mode, is executed in order to quickly reduce the braking force. This step 334
Is completed, the process proceeds to step 342 shown in FIG.
Is performed. On the other hand, if the condition of step 332 is not satisfied, it can be determined that the driver does not intend to reduce the braking force quickly. In this case, the process of step 336 is executed next.

In step 336, it is determined whether or not the _count value of the timer T _MODE has reached a predetermined time T _MODE3 . In the braking force control device according to the present embodiment, (III) the assist pressure gradual decrease mode is realized by repeating the assist pressure decreasing state and the assist pressure holding state as described above. The predetermined time T _MODE3 is a time that is set as a time to maintain the braking force control device in the assist pressure reduced state when execution of the (III) assist pressure gradual decrease mode is requested.

Therefore, in step 336, T _MODE ≧ T
If it is determined that _MODE3 is established, the period in which the braking force control device should be maintained in the assist pressure reduced state has ended, that is, the time has come for the braking force control device to be in the assist pressure holding state. Can be determined. In this case, following step 336, step 338 is performed.
Is performed.

In step 338, a process for requesting execution of the (IV) assist pressure holding mode, that is, a process for setting the (IV) assist pressure holding mode to the request mode is executed. When the process of step 338 is completed, the process of step 342 shown in FIG. 18 is executed. On the other hand, if it is determined in step 336 that T _MODE ≧ T _{MODE 3} is not established, it can be determined that the period in which the braking force control device should be maintained in the assist pressure reduced state has not ended. In this case, following step 336, step 340 follows.
Is performed.

At step 340, a process for requesting execution of the (VI) assist pressure gradual decrease mode, that is, a process for setting the (VI) assist pressure gradual decrease mode to the request mode, is executed. When the process of step 340 is completed,
Is performed in step 342 shown in FIG. According to the above-described processing, after the start of the execution of the (VI) assist pressure decrease / decrease mode is started, if the condition for requesting the (III) assist pressure reduction mode (the condition of step 332) is not satisfied,
After maintaining the request for the predetermined period T _MODE3 , the request mode can be changed to (IV) the assist pressure holding mode.

As described above, according to this routine, by executing the processing of steps 286 to 340, the control to be executed next is performed based on the currently executed control mode and the driver's brake operation. The mode can be determined, and the control mode can be defined as the request mode.
In step 342, it is determined whether execution of the (II) assist pressure increasing mode is requested. As a result, (II)
If it is determined that the assist pressure increasing mode is required, the process of step 344 is performed.

At step 344, the flag XPAINC is set.
Is turned on and the flags corresponding to the other control modes are turned off. When the process of step 344 is performed, it is determined that the control mode being executed is (II) the assist pressure increasing mode in the next processing cycle. When the process of step 344 ends, the process of step 346 is executed next.

At step 346, a process is executed for bringing the braking force control device into the assist pressure increasing state shown in FIG. After the process of step 346 is performed, the wheel cylinder pressure P _{W / C of} each wheel is immediately increased using the accumulator 28 as a hydraulic pressure source. When the process of step 346 ends, the current routine ends. If it is determined in step 342 that execution of the (II) assist pressure increasing mode has not been requested, then step 3
Forty-eight processes are executed.

In step 348, it is determined whether execution of the (III) assist pressure reduction mode has been requested.
As a result, if it is determined that (III) the assist pressure reduction mode has been requested, the process of step 350 is executed next. In step 350, a process of turning on the flag XPARED and turning off the flags corresponding to other control modes is executed. When the processing of step 350 is executed, it is determined that the control mode being executed is (III) the assist pressure reduction mode in the next processing cycle. When the process of step 350 ends, the process of step 352 is executed next.

In step 352, a process is executed for bringing the braking force control device into the assist pressure reducing state shown in FIG. After the processing of step 352 is executed, the wheel cylinder pressure P _{W / C of} each wheel is thereafter reduced to the master cylinder pressure P _{W / C.
The} pressure is quickly reduced with the lower limit of _{M / C.} Step 3
When the process of 52 is finished, the current routine is finished.

If it is determined in step 348 that (III) execution of the assist pressure reducing mode has not been requested, the process of step 354 is performed. In step 354, it is determined whether or not execution of the (V) assist pressure gradual increase mode is requested. As a result, if it is determined that (V) the assist pressure gradual increase mode is required, the process of step 356 is executed next.

In step 356, it is determined whether or not the request mode has changed from the previous processing cycle to the current processing cycle. As a result, when it is determined that the request mode has changed, it can be determined that (V) the assist pressure gradual increase mode is executed after the current processing cycle. In this case, the process of step 358 is executed next. On the other hand, if it is determined that the request mode has not changed from the previous processing cycle to the current processing cycle, it can be determined that (V) the assist pressure gradual increase mode has been executed before the previous processing cycle. In this case, the process of step 358 is jumped, and then the process of step 360 is executed.

In step 358, a process of storing the current master cylinder pressure P _{M / C} as the starting master cylinder pressure P _STA and clearing the count value of the timer T _MODE to “0” is executed. When the process of step 358 is completed, the process of step 360 is executed next. According to the above process, (V) every time the execution of the assist pressure gradual increase mode is newly started, the starting master cylinder pressure P _STA and the timer T _MODE can be cleared to the initial values.

At step 360, the flag XPASLI is set.
A process of turning on the NC and turning off flags corresponding to other control modes is executed. When the processing of step 360 is executed, it is determined that the control mode being executed is (V) the assist pressure gradual increase mode in the next processing cycle. When the process of step 360 ends, the process of step 362 is executed next.

At step 362, a process is executed for bringing the braking force control device into the assist pressure increasing state shown in FIG. When the process of step 362 ends, the current routine ends. As described above, in this embodiment,
(V) After the assist pressure gradual increase mode is set to the request mode, the request mode is changed to (IV) the assist pressure holding mode when a predetermined period T _MODE2 has elapsed. For this reason, according to the above processing, (V) every time execution of the assist pressure gradual increase mode is requested, the wheel cylinder pressure P _{W / C} is gradually increased gradually in a predetermined period T _MODE2 as one unit. Can be done.

If it is determined in step 354 that execution of the (V) assist pressure gradual increase mode has not been requested, the process of step 364 is next performed. In step 364, it is determined whether or not execution of the (VI) assist pressure gradual decrease mode is requested. As a result, if it is determined that execution of the (VI) assist pressure gradual decrease mode is requested, the process of step 366 is executed next.

In step 366, it is determined whether or not the request mode has changed from the previous processing cycle to the current processing cycle. As a result, when it is determined that the request mode has changed, it can be determined that (VI) the assist pressure gradual decrease mode is executed after the current processing cycle. In this case, the process of step 368 is executed next. On the other hand, if it is determined that the request mode has not changed from the previous processing cycle to the current processing cycle, it is determined that (VI) the assist pressure gradual decrease mode has been executed before the previous processing cycle. it can. In this case, the processing of step 368 is jumped, and then step 370
Is performed.

At step 368, step 358 is performed.
Similarly to the above, processing for clearing the starting master cylinder pressure P _STA and the timer T _MODE to the initial values is executed. When the process of step 368 is completed, the process of step 370 is executed next. According to the above processing, the start-time master cylinder pressure P _STA and the timer T _MODE can be cleared to the initial values every time the (VI) assist pressure gradual increase mode is newly started.

At step 370, the flag XPASLR
A process of turning on the ED and turning off flags corresponding to other control modes is executed. When the processing of step 370 is executed, it is determined that the control mode being executed is (VI) the assist pressure gradual decrease mode in the next processing cycle. When the process of step 370 ends, the process of step 372 is executed next.

At step 372, a process is executed for bringing the braking force control device into the assist pressure reducing state shown in FIG. When the process of step 372 ends, the current routine ends. As described above, in this embodiment,
(VI) After the assist pressure gradual decrease mode is set to the request mode, the request mode is changed to (IV) the assist pressure holding mode when a predetermined period T _MODE3 has elapsed. For this reason, according to the above processing, (VI) every time the execution of the assist pressure gradual decrease mode is requested, the wheel cylinder pressure P _{W / C} is gradually reduced gradually in a unit of the predetermined period T _MODE2. Can be done.

If it is determined in step 364 that execution of the (VI) assist pressure gradual decrease mode has not been requested, it can be determined that execution of the (IV) assist pressure holding mode has been requested. In this case, the process of step 374 is executed following step 364. Step 37
At 4, it is determined whether or not the request mode has changed from the last processing cycle to the current processing cycle.
As a result, if it is determined that the request mode has changed,
(IV) It can be determined that the assist pressure holding mode is executed after the current processing cycle. In this case, step 37
6 is executed. On the other hand, if it is determined that the request mode has not changed from the previous processing cycle to the current processing cycle, it can be determined that (IV) the assist pressure holding mode has been executed before the previous processing cycle. In this case, the process of step 376 is jumped, and then the process of step 378 is executed.

At step 376, step 35
As in 6,368, a process of clearing the starting master cylinder pressure P _STA and the timer T _MODE to initial values is executed. When the processing in step 376 is completed, the processing in step 378 is performed next. According to the above processing, (I
V) Every time the assist pressure holding mode is newly started, the starting master cylinder pressure P _STA and the timer T _MODE can be cleared to the initial values.

At the step 378, the flag XPAHOL
A process of turning on D and turning off flags corresponding to other control modes is executed. When the process of step 378 is executed, it is determined in the next processing cycle that the control mode being executed is (IV) the assist pressure holding mode. When the process of step 378 ends, the process of step 380 is executed next.

At step 380, a process is executed for bringing the braking force control device into the assist pressure holding state shown in FIG. When the process of step 380 is executed, the wheel cylinder pressure P _{W / C} of each wheel can be maintained at a constant value thereafter. When the process of step 380 ends, the current routine ends. As described above, according to the routine shown in FIGS. 12 to 18, after the execution of the BA control is started, the assist pressure Pa corresponding to the brake operation speed generated in the process of the emergency brake operation can be generated. At the same time, with the execution of the BA control, the wheel cylinder pressure P _{W / C} is appropriately increased or decreased in response to the increase or decrease in the master cylinder pressure P _{M / C} , that is, in response to the driver's brake operation. be able to. Therefore, according to the braking force control device of the present embodiment, when an emergency braking operation is performed by the driver, the braking force intended by the driver is promptly generated, and the braking force is always controlled during execution of the BA control. The driver's intention can be reflected in the power.

In the above embodiment, the hydraulic circuit of the braking force control device corresponds to the "braking hydraulic control mechanism" of the first embodiment, and the ECU 10 executes the control routine shown in FIG. By executing the control routine shown in FIG. 9, the “emergency brake operation detecting means” according to claim 1 is executed.
52 and the "start pressure increasing means" according to claim 1 by executing the processing of steps 260 to 266, and the ECU 10 executing the processing of steps 268 to 380 to control the "braking hydraulic pressure adjustment" according to claim 1. "Means" are each realized.

In the above embodiment, the ECU 1
0 corresponds to the above steps 356, 358, 366, 368, 3
By executing the processes of steps 74 and 376, the "start operation amount detecting means" according to the second and fourth embodiments is enabled by the ECU 10 to execute the steps 302, 304 and 3 described above.
The "first control state selecting means" according to claim 2, and the "third control state selecting means" according to claim 4, by executing the processing of steps 06, 308, 322 and 324.
The "pressure increasing gradient changing means" according to the fourth aspect is realized.

Further, in the above embodiment, the ECU 1
0 is the above-mentioned steps 290-308, 312-320, 3
The second control state selecting means according to claim 3 is executed by executing the processing of steps 22 and 324.
Executes the processing of steps 268 to 272, 276, 278 and 282, thereby realizing the "fourth control state selecting means" according to the fifth aspect.

In the above embodiment, the assist pressure increasing state shown in FIG. 4 and the assist pressure holding state shown in FIG. 5 are repeated to realize (V) the assist pressure gradual increasing mode. By repeating the assist pressure decreasing state shown in FIG. 6 and the assist pressure holding state shown in FIG. 5, (VI) the assist pressure gradual decreasing mode is realized,
(II) Pressure increasing gradient by the assist pressure increasing mode, (V) Pressure increasing gradient by the assist pressure decreasing mode, (III) Pressure decreasing gradient by the assist pressure decreasing mode, and (VI) Pressure decreasing gradient by the assist pressure decreasing mode And to make it different,
The present invention is not limited to this, (II) by increasing the pressure increasing gradient itself realized by the assist pressure increasing mode, and (III) by changing the pressure decreasing gradient itself realized by the assist pressure reducing mode A similar function may be realized.

Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 25 is a system configuration diagram of a pump-up type braking force control device (hereinafter, simply referred to as a braking force control device) corresponding to the second embodiment of the present invention. In FIG. 25, the same components as those shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted or simplified.

The braking force control device of this embodiment is a device suitable as a braking force control device for a front engine / rear drive type vehicle (FR vehicle). The braking force control device according to the present embodiment is controlled by the ECU 10. ECU10
Controls the operation of the braking force control device by executing the control routines shown in FIGS. 8 to 10 and FIGS. 12 to 18 as in the case of the first embodiment described above.

The braking force control device includes a brake pedal 12. A brake switch 14 is provided near the brake pedal 12. The ECU 10 controls the brake pedal 1 based on the output signal of the brake switch 14.
It is determined whether or not 2 is depressed. The brake pedal 12 is connected to a vacuum booster 400. The vacuum booster 400 is connected to the brake pedal 12.
When is depressed, an assist force Fa having a predetermined boosting ratio with respect to the brake depression force F is generated. A master cylinder 402 is fixed to the vacuum booster 400. The master cylinder 402 is a tandem center valve type master cylinder, and includes a first hydraulic chamber 404 and a second hydraulic chamber 406 therein. First
In the hydraulic chamber 404 and the second hydraulic chamber 406, a master cylinder pressure PM _{/ C} is generated according to the resultant force of the brake depression force F and the assist force Fa.

A reservoir tank 408 is provided above the master cylinder 402. Reservoir tank 408
, A front reservoir passage 410 and a rear reservoir passage 412 communicate with each other. A front reservoir cut solenoid 414 is provided in the front reservoir passage 410.
(Hereinafter, referred to as SRCF 414). Similarly, a rear reservoir cut solenoid 416 (hereinafter, referred to as SRCR 416) communicates with the rear reservoir passage 412.

A front pump passage 418 communicates with the SRCF 414. Similarly, SRCR416
Is connected to a rear pump passage 420. SRCF
Reference numeral 414 denotes a two-position solenoid valve that shuts off the front reservoir passage 410 and the front pump passage 418 when turned off and conducts them when turned on. The SRCR 416 is a two-position solenoid valve that shuts off the rear reservoir passage 412 and the rear pump passage 420 when turned off, and conducts them when turned on.

First hydraulic chamber 40 of master cylinder 402
A first hydraulic passage 422 and a second hydraulic passage 424 communicate with the fourth hydraulic chamber 406 and the second hydraulic chamber 406, respectively. The first hydraulic passage 422 includes a right front master cut solenoid 426 (hereinafter, referred to as SMFR 426), and
Left front master cut solenoid 428 (hereinafter referred to as SMFL4
28). On the other hand, the second hydraulic passage 42
4 has a rear master cut solenoid 430 (hereinafter referred to as S
MR430).

A hydraulic passage 432 provided corresponding to the right front wheel FR communicates with the SMFR 426. Similarly,
A hydraulic passage 434 provided corresponding to the left front wheel FL communicates with the SMFL 428. Further, the SMR 430 communicates with hydraulic pressure passages 436 provided corresponding to the left and right rear wheels RL, RR. SMFR426, SMFL42
8 and the SMR 430 are provided with constant pressure release valves 438, 440, 442, respectively. SMFR4
Reference numeral 26 denotes a state in which the first hydraulic passage 422 and the hydraulic passage 432 are electrically connected to each other when turned off, and the first hydraulic passage 42 through the constant pressure release valve 438 when turned on.
2 is a two-position solenoid valve that communicates with the hydraulic passage 432. When the SMFL 426 is turned off, the first hydraulic passage 422 and the hydraulic passage 434 are brought into a conductive state, and when the SMFL 426 is turned on, the first hydraulic passage 422 is connected via a constant pressure release valve 440. This is a two-position solenoid valve that connects the fluid pressure passage 422 to the hydraulic pressure passage 434. Similarly, SMR 430 is
When turned off, the second hydraulic passage 424 and the hydraulic passage 436 are brought into conduction, and when turned on, the second hydraulic passage 424 and the hydraulic passage are connected via the constant pressure release valve 442. 436 is a two-position solenoid valve that communicates with 436.

Between the first hydraulic passage 422 and the hydraulic passage 432, the hydraulic passage 43 extends from the first hydraulic passage 422 side.
Check valve 44 that allows only fluid flow toward side 2
4 are provided. Similarly, a first hydraulic passage 422 is provided between the first hydraulic passage 422 and the hydraulic passage 434 and between the second hydraulic passage 424 and the hydraulic passage 436.
A check valve 446 that allows only the flow of the fluid from the side to the hydraulic passage 434 and a check valve 448 that allows only the flow of the fluid from the second hydraulic passage 424 to the hydraulic passage 436. It is arranged.

Hydraulic passages 4 provided corresponding to the left and right front wheels
As in the case of the first embodiment, the holding solenoid S ** H, the pressure reducing solenoid S ** R, and the wheel cylinders 120 to 434 are provided in the hydraulic passages 436 provided corresponding to the right and left rear wheels. 126 and check valves 128-134 are in communication. The left and right front wheel holding solenoid SFR
A front pressure reducing passage 450 communicates with R112 and SFLR114. Further, a rear pressure reducing passage 452 communicates with the holding solenoids SRRR116 and SRLR118 of the left and right rear wheels.

A front reservoir 454 and a rear reservoir 455 communicate with the front pressure reducing passage 450 and the rear pressure reducing passage 452, respectively. The front reservoir 454 and the rear reservoir 455 are each provided with a check valve 4
The suction side of the front pump 460 through 56, 458,
And, it communicates with the suction side of the rear pump 462. The discharge side of the front pump 460 and the rear pump 46
2 has a damper 4 for absorbing the pulsation of the discharge pressure.
64,466. The damper 464 includes a front right pump passage 468 provided corresponding to the front right wheel FR and a front left pump passage 470 provided corresponding to the front left wheel FL.
Is in communication with On the other hand, the damper 466 is
It communicates with 6.

The right front pump passage 468 communicates with the hydraulic passage 432 via a right front pump solenoid 472 (hereinafter referred to as SPFL 472). The front left pump passage 470 is connected to a front left pump solenoid 474 (hereinafter referred to as SPF).
R474) to the hydraulic passage 434. The SPFL 472 is a two-position solenoid valve that brings the right-front pump passage 468 and the hydraulic passage 432 into conduction when turned off, and shuts off them when turned on. Similarly, SPFR47
4 is a left front pump passage 47
The solenoid valve is a two-position solenoid valve that establishes a conductive state between 0 and the hydraulic pressure passage 434, and shuts them off when turned on.

Between the hydraulic passage 432 and the right front pump passage 468, the right front pump passage 468 is located from the hydraulic passage 432 side.
Constant pressure release valve 476 that allows only fluid flow toward the side
Are arranged. Similarly, between the hydraulic pressure passage 434 and the left front pump passage 470, a constant pressure release valve 478 that allows only the fluid flow from the hydraulic pressure passage 434 to the left front pump passage 470 is disposed.

Near each wheel, a wheel speed sensor 136,
138, 140, 142 are provided. ECU10
Detects the rotational speed V _W of each wheel based on the output signal of the wheel speed sensors 136-142. A hydraulic pressure sensor 144 is provided in the second hydraulic pressure passage 424 communicating with the master cylinder 402. The ECU 10 detects the master cylinder pressure PM _{/ C} based on the output signal of the hydraulic pressure sensor 144.

Next, the operation of the braking force control device of this embodiment will be described. The braking force control device according to the present embodiment switches the state of various solenoid valves provided in the hydraulic circuit to provide a normal brake function, an ABS function, and a B function.
A function is realized. The normal braking function is realized by turning off all the solenoid valves provided in the braking force control device as shown in FIG. Hereinafter, the state shown in FIG. 25 is referred to as a normal brake state. Further, control for realizing the normal brake function in the braking force control device is referred to as normal brake control.

In the normal braking state shown in FIG.
Wheel cylinders 120, 122 for left and right front wheels FL, FR
Are connected via the first hydraulic passage 422 to the master cylinder 4
02 communicates with the first hydraulic chamber 404. The wheel cylinders 124, 126 of the left and right rear wheels RL, RR are
The hydraulic pressure passage 424 communicates with the second hydraulic chamber 406 of the master cylinder 402. In this case, the wheel cylinder pressure P _{W / C} of the wheel cylinders 120 to 126 is controlled to be always equal to the master cylinder pressure P _{M / C.} Therefore, FIG.
According to the state shown in FIG. 5, the normal braking function is realized.

In the ABS function, in the state shown in FIG. 25, the front pump 460 and the rear pump 462 are turned on, and the holding solenoid S ** H and the pressure reducing solenoid S ** R are appropriately driven according to the request of the ABS. It is realized by doing. Hereinafter, control for realizing the ABS function in the braking force control device is referred to as ABS control.

The ECU 10 starts the ABS control when the vehicle is in a braking state and an excessive slip ratio is detected for any of the wheels. The ABS control is started in a situation where the brake pedal 12 is depressed, that is, in a situation where the master cylinder 402 is generating a high master cylinder pressure PM _{/ C.} During the execution of the ABS control, the master cylinder pressure P _{M / C} is supplied via the first hydraulic pressure passage 422 and the second hydraulic pressure passage 424 to the hydraulic pressure passages 432 and 434 provided corresponding to the left and right front wheels, respectively. and,
It is guided to a hydraulic passage 436 provided corresponding to the left and right rear wheels. Therefore, when the holding solenoid S ** H is opened and the pressure reducing solenoid S ** R is closed in such a situation, the wheel cylinder pressure P _{W / C} of each wheel can be increased. Hereinafter, this state is referred to as (i) pressure increase mode.

If both the holding solenoid S ** H and the pressure reducing solenoid S ** R are closed during the execution of the ABS control, the wheel cylinder pressure P _{W / C} of each wheel can be held. . Hereinafter, this state is referred to as (ii) holding mode. Further, during the execution of the ABS control, the holding solenoid S ** H is closed, and the pressure reducing solenoid S ** is closed.
When R is in the valve open state, the wheel cylinder pressure P of each wheel
_{W / C} can be reduced. Hereinafter, this state is referred to as (iii)
This is called a decompression mode.

During the ABS control, the ECU 10 sets the slip state of each wheel so that the above-mentioned (i) pressure increasing mode, (ii) holding mode, and (iii) pressure reducing mode are appropriately realized for each wheel. , The holding solenoid S ** H and the pressure reducing solenoid S ** R are controlled. Holding solenoid S **
When H and the pressure reducing solenoid S ** R are controlled as described above, the wheel cylinder pressures P _{W / C of} all the wheels are controlled to appropriate pressures without generating an excessive slip ratio on the corresponding wheels. . Thus, according to the above control,
An ABS function can be realized in the braking force control device.

When the decompression mode is performed on each wheel during the execution of the ABS control, the brake fluid in the wheel cylinders 120 to 126 is passed through the front decompression passage 450 and the rear decompression passage 452 and the front reservoir 454 and the rear reservoir 455 are operated. Flows into. Front reservoir 4
The brake fluid flowing into the rear reservoir 455 and the front pump 460 and the rear pump 462
And supplied to the hydraulic passages 432, 434, 436.

A part of the brake fluid supplied to the hydraulic passages 432, 434, and 436 flows into the wheel cylinders 120 to 126 when the pressure increase mode is performed in each wheel. The remainder of the brake fluid flows into the master cylinder 402 to compensate for the outflow of the brake fluid. Therefore, according to the system of the present embodiment, the ABS
Excessive stroke of the brake pedal 12 does not occur during execution of the control.

FIGS. 26 to 28 show the state of the braking force control device for realizing the BA function. The ECU 10
The BA function is realized by appropriately realizing the states shown in FIGS. 26 to 28 after the driver performs a brake operation that requests a quick rise in braking force, that is, an emergency brake operation. Hereinafter, the control for realizing the BA function in the braking force control device is referred to as BA control.

FIG. 26 shows an assist pressure increasing state realized during execution of the BA control. The assist pressure increase state is B
When it is necessary to increase the wheel cylinder pressure P _{W / C} of each wheel during the execution of the A control, that is, during the BA control,
This is realized when execution of (I) start pressure increasing mode, (II) assist pressure increasing mode, and (V) assist pressure gradual increasing mode is requested.

In the system of the present embodiment, as shown in FIG. 26, the assist pressure increasing state during the BA control is performed by the reservoir cut solenoids SRCF414 and SRCR41.
6, and master cut solenoid SMFR426,
SMFL428 and SMR430 are turned on, and
This is realized by turning on the front pump 460 and the rear pump 462.

When the assist pressure increasing state shown in FIG. 26 is realized, the brake fluid stored in reservoir tank 408 is supplied to front pump 460 and rear pump 4.
62 and hydraulic passages 432, 434, 436
Supplied to In the assist pressure increasing state, the hydraulic pressure passage 43
2,434,436 are constant pressure release valves 438,44.
The hydraulic pressure passages 432, 434, and 4 will not exceed the valve opening pressure of 0,442 until the pressure becomes higher than the master cylinder pressure PM _{/ C.}
The flow of brake fluid from 36 to the master cylinder 402 is SMFR326, SMFL328, SMR3.
Blocked by 30.

When the assist pressure increasing state shown in FIG. 26 is realized, the hydraulic pressure passages 432, 434,
At 436, a hydraulic pressure higher than the master cylinder pressure PM _{/ C} is generated. In the assist pressure increasing state, the wheel cylinders 120 to 126 and the corresponding hydraulic passages 33 are arranged.
2, 334, 336 are maintained in a conductive state. Therefore, when the assist pressure increasing state is realized, thereafter, the wheel cylinder pressure P _{W / C} of all the wheels is quickly changed to the master cylinder pressure P _{M / C} using the front pump 460 or the rear pump 462 as a hydraulic pressure source. The pressure is raised to a pressure exceeding.

In the assist pressure increasing state shown in FIG. 26, the hydraulic passages 434, 432, and 436 communicate with the master cylinder 402 via check valves 444, 446, and 448, respectively. For this reason, when the master cylinder pressure P _{M / C} is larger than the wheel cylinder pressure P _{W / C} of each wheel, even in the assist pressure increasing state, the wheel cylinder pressure P _W is set using the master cylinder 402 as a hydraulic pressure source. _{/ C} can be boosted.

FIG. 27 shows an assist pressure holding state realized during execution of the BA control. The assist pressure holding state is B
This is realized when it is necessary to hold the wheel cylinder pressure P _{W / C} of each wheel during the execution of the A control, that is, when the (IV) assist pressure holding mode is required during the BA control. As shown in FIG. 27, the assist pressure holding state includes master cut solenoids SMFR426, SMFL428, SMR4.
This is realized by turning on the switch 30.

In the assist pressure holding state shown in FIG. 27, the front pump 460, the reservoir tank 408,
Rear pump 462 and reservoir tank 408 are shut off by SRCFs 414 and 416, respectively. For this reason, in the assist pressure holding state, the hydraulic pressure passage 432,
No fluid is ejected to 434,436. In the assist pressure holding state shown in FIG.
32,434,436 are SMFR426, SMFL4
24, which is substantially separated from the master cylinder 402 by the SMR 430. For this reason, according to the assist pressure holding state shown in FIG. 27, the wheel cylinder pressures P _{W / C} of all the wheels can be held at a constant value.

FIG. 28 shows a reduced assist pressure state realized during execution of the BA control. The assist pressure reduction state is B
When it is necessary to reduce the wheel cylinder pressure P _{W / C} of each wheel during the execution of the A control, that is, during the BA control, (III)
This is realized when execution of the assist pressure reduction mode and the (VI) assist pressure gradual reduction mode are requested. The assist pressure reduction state is realized by turning off all the solenoids as shown in FIG.

In the assist pressure reducing state shown in FIG. 28, the front pump 460 and the rear pump 462 are disconnected from the reservoir tank 408. For this reason, the hydraulic passage 43 is connected to the front pump 462 and the rear pump 462.
No fluid is discharged to 2,434,436. Further, in the assist pressure reduced state, the wheel cylinders 120 to 126 of each wheel and the master cylinder 402 are in a conductive state. Therefore, when the assist pressure reduction state is realized, 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.

In this embodiment, when the driver performs an emergency braking operation, the ECU 10 increases the assist pressure increasing state shown in FIGS. 26 to 28 as in the case of the first embodiment. The BA function is realized by combining the assist pressure holding state and the assist pressure decreasing state.
For this reason, according to the braking force control device of the present embodiment, similarly to the case of the above-described first embodiment, when the driver performs an emergency braking operation, the braking force intended by the driver is promptly reduced. The driver's intention can be reflected on the braking force during the execution of the BA control and during the execution of the BA control.

In the braking force control device of the present embodiment, when the above-described BA control is started, the wheel cylinder pressure P _{W / C of} each wheel is immediately increased, so that any one of the wheels becomes excessive. A high slip ratio may occur. In such a case, the ECU 10 determines that BA + ABS
Start control. Hereinafter, the operation of the braking force control device accompanying the BA + ABS control will be described with reference to FIGS.

[0224] The braking force control device according to the present embodiment is composed of BA + AB.
After the S control is started, when the driver performs a brake operation intended to increase the braking force, the wheel cylinder pressure P _{W / C} of the ABS target wheel is controlled to a pressure according to the request of the ABS control, Increase the wheel cylinder pressure P _{W / C} of the other wheels. FIG. 29 shows a state (hereinafter referred to as “assist pressure increase (ABS)”) that is implemented to perform the above-described function during execution of the BA + ABS control using the left front wheel FL as an ABS target wheel.
State). The assist pressure increase (ABS) state is determined by the rear reservoir cut solenoid SRCR416 and the master cut solenoids SMFR426 and SMF.
L428 and SMR430 are turned on, the front pump 460 and the rear pump 462 are turned on, and the holding solenoid SFLH106 and the pressure reducing solenoid SFLR114 of the left front wheel FL are appropriately controlled according to the ABS control request.

In the assist pressure increasing (ABS) state,
The brake fluid discharged from the rear pump 462 is supplied to the wheel cylinders 124 and 126 of the left and right rear wheels RL and RR, as in the case of the assist pressure increasing state shown in FIG. For this reason, when the assist pressure increase (ABS) state is realized, the wheel cylinder pressure P _{W / C} of the left and right rear wheels RL, RR becomes the same as when the assist pressure increase state is realized during the BA control. It is boosted.

BA + with left front wheel FL as ABS target wheel
The ABS control is started when the (ii) depressurization mode is executed for the left front wheel FL. Therefore, the brake fluid flows into the front reservoir 454 at the same time when the BA + ABS control is started. In the assist pressure increasing (ABS) state shown in FIG.
Sucks and feeds the brake fluid flowing into the front reservoir 454 in this manner.

The brake fluid pumped by the front pump 460 is mainly supplied to the wheel cylinder 120 of the right front wheel FR, and is also supplied to the wheel cylinder 122 when the pressure increasing mode is executed for the left front wheel FL. Is done. According to the above control, the wheel cylinder pressure P _{W / C} of the right front wheel FR is increased in the same manner as when the assist pressure increase state is realized during the BA control, and the wheel cylinder pressure P _{W / C} of the left front wheel FL is increased. _{W / C} can be controlled to an appropriate value that does not cause an excessive slip ratio on the left front wheel FL.

As described above, according to the assist pressure increasing (ABS) state shown in FIG. 29, the wheel cylinder pressure P _{W / C} of the left front wheel FL, which is the ABS subject wheel, is controlled to a pressure according to the ABS control request. In addition, the wheel cylinder pressure P _{W / C} of the right front wheel FR and the left and right rear wheels RL and RR, which are the non-object wheels of the ABS control, is quickly changed as in the case where the assist pressure increasing state is realized during the BA control. Can be boosted.

The braking force control device according to the present embodiment is configured as follows: BA + AB
After the S control is started, when the driver performs a brake operation intended to maintain the braking force, the wheel cylinder pressure P _{W / C} of the ABS target wheel is controlled to a pressure according to the request of the ABS control, The wheel cylinder pressure P _{W / C} of the other wheels is maintained. FIG. 30 shows a state (hereinafter referred to as “assist pressure holding (ABS)”) that is realized to perform the above-described function during the execution of the BA + ABS control in which the left front wheel FL is the ABS target wheel.
State). The assist pressure holding (ABS) state is determined by the master cut solenoid SMFR426, SMFL.
428 and SMR 430 are turned on, the front pump 460 and the rear pump 462 are turned on, and the holding solenoid SFRH104 of the right front wheel FR is turned on.
In addition, this is realized by appropriately controlling the holding solenoid SFLH106 and the pressure reducing solenoid SFLR114 of the left front wheel FL in response to a request for ABS control.

In the assist pressure holding (ABS) state,
The rear pump 462 is shut off from the reservoir tank 408 as in the case where the assist pressure holding state shown in FIG. 27 is realized. Further, the hydraulic passage 430 is substantially shut off from the master cylinder 402 as in the case where the assist pressure holding state shown in FIG. 27 is realized. For this reason,
When the assist pressure holding (ABS) state is realized, the wheel cylinder pressures P _{W / C} of the left and right rear wheels RL and RR are held at a constant value as in the case where the assist pressure holding state is realized during the BA control. You.

At the same time as the assist pressure holding (ABS) state is realized, or before the assist pressure holding (ABS) state is realized,
The brake fluid flowing out of the wheel cylinder 122 is stored. The front pump 460 sucks and pumps the brake fluid stored in the front reservoir 454 while the assist pressure holding (ABS) state is realized.

In the assist pressure holding state, the right front wheel FR
Of the wheel cylinder 120 by the SFRH 104
It is separated from the front pump 460. For this reason,
Brake full pumped by front pump 460
Is supplied only to the wheel cylinder 122 of the left front wheel FL
Is done. In addition, the wheel pump
The brake fluid flows into the left front wheel FL
(I) Permitted only when pressure boost mode is performed
You. According to the above processing, the wheel cylinder of the right front wheel FR
Pressure P_{W / C}Is maintained at a constant value, and the front left wheel FL
Il cylinder pressure P _{W / C}But excessive slip on left front wheel FL
It is controlled to an appropriate pressure without generating a rate.

As described above, according to the assist pressure increase (ABS) state shown in FIG. 30, the wheel cylinder pressure P _{W / C} of the left front wheel FL, which is the ABS target wheel, is adjusted to an appropriate pressure according to the ABS control request. And the wheel cylinder pressures P _{W / C} of the right front wheel FR and the left and right rear wheels RL and RR, which are non-object wheels of the ABS control, are constant as in the case where the assist pressure holding state is realized during the BA control. Can be held to a value.

The braking force control device according to the present embodiment is configured as follows: BA + AB
After the S control is started, when the driver performs a brake operation intended to reduce the braking force, the wheel cylinder pressure P _{W / C} of the ABS target wheel is controlled to a pressure according to the request of the ABS control, Reduce the wheel cylinder pressure P _{W / C} of the other wheels. The above-described function realizes the assist pressure reduction state shown in FIG.
According to the request of the ABS control, the holding solenoid S ** H and the pressure reducing solenoid S ** R are appropriately set so that (i) the pressure increasing mode, (ii) the holding mode, and (iii) the pressure reducing mode are realized.
Is realized by controlling Hereinafter, a state in which such control is being performed is referred to as an assist pressure reduction (ABS) state.

That is, when the assist pressure reduction (ABS) state is realized, all the holding solenoids S ** H
Communicates with the master cylinder 402. Therefore, when the assist pressure reduction (ABS) control is realized, the wheel cylinder pressure P _{W / C} of the wheel not controlled by the ABS control can be reduced using the master cylinder pressure P _{M / C} as a lower limit.
In addition, the wheel cylinder pressure P _{W / C} can be held or reduced for the target wheel of the ABS control by realizing the (ii) holding mode and (iii) the pressure reducing mode.

The assist pressure reduction (ABS) state is set when the driver intends to reduce the braking force, that is, when it is not necessary to increase the wheel cylinder pressure P _{W / C of} any wheel. Is achieved. Therefore, if the (ii) holding mode and (iii) the decompression mode can be realized as described above, the wheel cylinder pressure P _{W / C} of the ABS target wheel is appropriately controlled to the pressure required by the BA + ABS control. can do.

As described above, the assist pressure reduction (A
According to the BS) state, while controlling the wheel cylinder pressure P _{W / C} of the ABS target wheel to an appropriate pressure according to the request of the ABS control, the right front wheel FR and the left and right rear wheels RL which are not the target wheels of the ABS control. , RR wheel cylinder pressure P _{W / C} , B
As in the case where the assist pressure reduction state is realized during the A control, the pressure can be reduced using the master cylinder pressure P _{M / C} as the lower limit.

As described above, according to the braking force control device of the present embodiment, when an excessive slip ratio occurs in any of the wheels after the BA control is started, the wheel cylinder pressure P of the ABS target wheel is increased. _The ABS function for suppressing the _{W / C} to an appropriate pressure required by the ABS control, and the wheel cylinder pressure P _{W / C} of the wheel not controlled by the ABS control is set to a higher pressure than the master cylinder pressure PM _{/ C.} In the region, the BA function of increasing or decreasing according to the driver's brake operation can be realized at the same time.

Next, a third embodiment of the present invention will be described with reference to FIGS. FIG. 31 is a system configuration diagram of a pump-up type braking force control device (hereinafter, simply referred to as a braking force control device) corresponding to the third embodiment of the present invention. In FIG. 31, the same components as those shown in FIG. 25 are denoted by the same reference numerals, and description thereof will be omitted or simplified.

The braking force control device of this embodiment is a device suitable as a braking force control device for a front engine / front drive type vehicle (FF vehicle). The braking force control device according to the present embodiment is controlled by the ECU 10. ECU
The operation of the braking force control device 10 is performed by executing the control routines shown in FIGS. 8 to 10 and FIGS. 12 to 18 as in the first and second embodiments. Control.

The braking force control device has a brake pedal 12. A brake switch 14 is provided near the brake pedal 12. The ECU 10 controls the brake pedal 1 based on the output signal of the brake switch 14.
It is determined whether or not 2 is depressed. The brake pedal 12 is connected to a vacuum booster 400. The vacuum booster 400 is fixed to the master cylinder 402. A first hydraulic chamber 404 and a second hydraulic chamber 406 are formed inside the master cylinder 402. First hydraulic chamber 404 and second hydraulic chamber 406
Inside the brake pedal force F and the vacuum booster 4
A master cylinder pressure P _{M / C} is generated according to the resultant force with the assist force Fa at which 00 is generated.

A reservoir tank 408 is provided above master cylinder 400. Reservoir tank 408
, A first reservoir passage 500 and a second reservoir passage 502 communicate with each other. A first reservoir cut solenoid 504 (hereinafter, SR)
C- ₁ 504). Similarly, a second reservoir cut solenoid 5 is provided in the second reservoir passage 502.
06 (hereinafter, referred to as SRC- ₂ 506).

The first pump passage 508 communicates with the SRC _-1 504. Similarly, a second pump passage 510 communicates with SRC- ₂ 506. SRC _- 15
04 is turned off, so that the first reservoir passage 50
0 is a two-position solenoid valve that shuts off the first pump passage 508 and turns on when turned on. SRC- ₂ 506 is a two-position solenoid valve that shuts off the second reservoir passage 502 and the second pump passage 510 by being turned off, and conducts them by being turned on. is there.

First hydraulic chamber 40 of master cylinder 402
A first hydraulic passage 422 and a second hydraulic passage 424 communicate with the fourth hydraulic chamber 406 and the second hydraulic chamber 406, respectively. The first hydraulic passage 422 communicates with a first master cut solenoid 512 (hereinafter, referred to as SMC- ₁ 512). On the other hand, a second master cut solenoid 514 (hereinafter, referred to as SMC- ₂ 514) communicates with the second hydraulic passage 424.

The SMC _-1 512 has a first pump pressure passage 5
16 and a hydraulic passage 518 provided corresponding to the left rear wheel RL.
And are in communication. The first pump pressure passage 516 has the first
A pump solenoid 520 (hereinafter, referred to as SMV- ₁ 520) is in communication. The SMV _-1 520 further communicates with a hydraulic passage 522 provided corresponding to the right front wheel FR. A constant pressure release valve 524 is provided inside the SMV _-1 520. The SMV _-1 520 makes the first pump pressure passage 516 and the fluid pressure passage 522 conductive when turned off, and the constant pressure release valve 5 when turned on.
The solenoid valve is a two-position solenoid valve that allows them to communicate with each other via the reference numeral 24. Between the first pump pressure passage 516 and the hydraulic pressure passage 522, and from the first pump pressure passage 516 side,
Check valve 52 that allows only fluid flow toward side 2
6 are provided.

The SMC- ₂ 514 has a second pump pressure passage 5
And hydraulic passages 530 provided corresponding to right rear wheel RR.
And are in communication. The second pump pressure passage 528 has a second
A pump solenoid 532 (hereinafter, referred to as SMV- ₂ 532) communicates therewith. The SMV- ₂ 532 further communicates with a hydraulic passage 534 provided corresponding to the left front wheel FL. Inside the SMV- ₂ 532, a constant pressure release valve 536 is provided. The SMV- ₂ 532 makes the second pump pressure passage 528 and the hydraulic pressure passage 534 conductive when turned off, and the constant pressure release valve 5 when turned on.
It is a two-position solenoid valve that connects them through 36. Between the first pump pressure passage 528 and the fluid pressure passage 534, and from the second pump pressure passage 528 side,
Check valve 53 that allows only fluid flow toward 6
8 are provided.

Inside the SMC- ₁ 512 and SMC- ₂ 514, constant pressure release valves 540 and 542 are provided, respectively. The SMC- ₁ 512 makes the first hydraulic passage 422 and the hydraulic passage 518 (and the first pump pressure passage 516) conductive when turned off, and releases the constant pressure when turned on. It is a two-position solenoid valve that connects them via a valve 540. Also, when the SMC- ₂ 514 is turned off, the second hydraulic passage 424 and the hydraulic passage 5
30 (and the second pump pressure passage 528), and is a two-position solenoid valve that connects them via the constant pressure release valve 442 when turned on.

A check valve 544 is provided between the first hydraulic passage 422 and the hydraulic passage 518 to allow only fluid flow from the first hydraulic passage 422 to the hydraulic passage 518. ing. Similarly, a check valve 54 between the second hydraulic passage 424 and the hydraulic passage 530 that allows only the flow of the fluid from the second hydraulic passage 424 to the hydraulic passage 530 is provided.
6 are provided.

The four hydraulic passages 516, 522, 528, 534 provided corresponding to the left and right front wheels and the left and right rear wheels have holding solenoids S * as in the first and second embodiments. * H, the pressure reducing solenoid S ** R, the wheel cylinders 120 to 126, and the check valves 128 to 134 are in communication. The pressure reducing solenoids SFRR112 and SRLR118 of the right front wheel FR and the left rear wheel RL include:
The first pressure reduction passage 548 communicates with the first pressure reduction passage 548. Furthermore, the left front wheel FL
The second pressure reducing passage 550 communicates with the pressure reducing solenoids SFLR114 and SRRR116 of the right rear wheel RR.

First pressure reducing passage 548 and second pressure reducing passage 5
A first reservoir 552 and a second reservoir 554 communicate with 50, respectively. Also, the first reservoir 552
And the second reservoir 554 are each provided with a check valve 556,
It communicates with the suction side of the first pump 560 and the suction side of the second pump 562 via 558. First pump 5
60, and the discharge side of the second pump 562,
It communicates with dampers 564 and 566 for absorbing the pulsation of the discharge pressure. The dampers 564 and 566 communicate with the hydraulic passages 522 and 534, respectively.

In the vicinity of each wheel, a wheel speed sensor 136,
138, 140, 142 are provided. ECU10
Detects the rotational speed V _W of each wheel based on the output signal of the wheel speed sensors 136-142. Further, a hydraulic pressure sensor 144 is provided in the second hydraulic pressure passage 324 communicating with the master cylinder 302. The ECU 10 detects the master cylinder pressure PM _{/ C} based on the output signal of the hydraulic pressure sensor 144.

Next, the operation of the braking force control device of this embodiment will be described. The braking force control device according to the present embodiment switches the state of various solenoid valves provided in the hydraulic circuit to provide a normal brake function, an ABS function, and a B function.
A function is realized. The normal braking function is realized by turning off all the solenoid valves provided in the braking force control device as shown in FIG. Hereinafter, the state shown in FIG. 31 is referred to as a normal brake state. Further, control for realizing the normal brake function in the braking force control device is referred to as normal brake control.

In the normal braking state shown in FIG.
The wheel cylinder 120 of the right front wheel FR and the wheel cylinder 126 of the left rear wheel RL both communicate with the first hydraulic chamber 404 of the master cylinder 402 via the first hydraulic passage 422. The wheel cylinder 122 of the left front wheel FL and the wheel cylinder 124 of the right rear wheel RR are both connected to the second hydraulic chamber 406 of the master cylinder 402 via the second hydraulic pressure passage 424. In this case, the wheel cylinder 12
The wheel cylinder pressure P _{W / C} of 0 to 126 is always controlled to be equal to the master cylinder pressure P _{M / C.} Therefore, according to the state shown in FIG. 31, the normal braking function is realized.

In the ABS function, in the state shown in FIG. 31, the first pump 560 and the second pump 562 are turned on, and the holding solenoid S ** H and the pressure reducing solenoid S ** R are switched according to the ABS request. This is realized by appropriate driving. Hereinafter, control for realizing the ABS function in the braking force control device is referred to as ABS control.

During the execution of the ABS control, the four hydraulic passages 518, 5 provided corresponding to the left and right front wheels and the left and right rear wheels, respectively.
A high master cylinder pressure P _{M / C} is led to all of 22, 22, 534. Therefore, when the holding solenoid S ** H is opened and the pressure reducing solenoid S ** R is closed in such a situation, the wheel cylinder pressure P _{W / C} of each wheel can be increased. Hereinafter, this state
(i) This is referred to as pressure increase mode.

If both the holding solenoid S ** H and the pressure reducing solenoid S ** R are closed during the execution of the ABS control, the wheel cylinder pressure P _{W / C} of each wheel can be held. . Hereinafter, this state is referred to as (ii) holding mode. Further, during the execution of the ABS control, the holding solenoid S ** H is closed, and the pressure reducing solenoid S ** is closed.
When R is in the valve open state, the wheel cylinder pressure P of each wheel
_{W / C} can be reduced. Hereinafter, this state is referred to as (iii)
This is called a decompression mode.

[0257] During the execution of the ABS control, the ECU 10 appropriately sets (i) the pressure increasing mode, (ii) the holding mode,
And (iii) controlling the holding solenoid S ** H and the pressure reducing solenoid S ** R according to the slip state of each wheel so that the pressure reducing mode is realized. Holding solenoid S
When ** H and the pressure reducing solenoid S ** R are controlled as described above, the wheel cylinder pressures P _{W / C of} all the wheels are controlled to appropriate pressures without generating an excessive slip ratio on the corresponding wheels. Is done. As described above, according to the above control, the ABS function can be realized in the braking force control device.

When the decompression mode is performed on each wheel during the execution of the ABS control, the brake fluid in the wheel cylinders 120 to 126 flows through the first decompression passage 548 and the second decompression passage 550 to the first reservoir 552. And flows into the second reservoir 554. The brake fluid flowing into the first reservoir 552 and the second reservoir 554
The water is pumped by the pump 560 and the second pump 562 and supplied to the hydraulic passages 522 and 534.

A part of the brake fluid supplied to the hydraulic passages 522 and 534 flows into the wheel cylinders 120 to 126 when (i) the pressure increasing mode is performed in each wheel. The remainder of the brake fluid flows into the master cylinder 402 to compensate for the outflow of the brake fluid.
Therefore, according to the system of the present embodiment, an excessive stroke does not occur on the brake pedal 12 during execution of the ABS control.

FIGS. 32 to 34 show the state of the braking force control device for realizing the BA function. The ECU 10
The BA function is realized by appropriately realizing the states shown in FIGS. 32 to 34 after the driver performs a brake operation that requests a quick rise of the braking force, that is, the emergency brake operation. Hereinafter, the control for realizing the BA function in the braking force control device is referred to as BA control.

FIG. 32 shows an assist pressure increasing state realized during execution of the BA control. The assist pressure increase state is B
When it is necessary to increase the wheel cylinder pressure P _{W / C} of each wheel during the execution of the A control, that is, during the BA control,
This is realized when execution of (I) start pressure increasing mode, (II) assist pressure increasing mode, and (V) assist pressure gradual increasing mode is requested.

In the system of this embodiment, the assist pressure increasing state during the BA control is as shown in FIG. 32, where the reservoir cut solenoids SRC- ₁ 504 and SRC- ₂ 50
6, and master cut solenoid SMC- ₁ 512
SMC _-2 514 is turned on and the first pump 56
This is realized by turning on the 0 and the second pump 562.

When the assist pressure increasing state is realized during the execution of the BA control, the brake fluid stored in the reservoir tank 408 is pumped up by the first pump 560 and the second pump 562, and the hydraulic pressure passages 522 and 534 are provided. Supplied to In the assist pressure increasing state, the fluid pressure passage 522, the wheel cylinder 120 of the right front wheel FR, and the wheel cylinder 126 of the left rear wheel RL are maintained in a conductive state. In the assist pressure increasing state, the pressure on the hydraulic pressure passage 522 side exceeds the valve opening pressure of the constant pressure release valve 540, and the master cylinder pressure P _{M / C}
Until the pressure becomes higher than that of the fluid, the flow of the fluid from the hydraulic passage 522 toward the master cylinder 402 is SMC _−1.
Inhibited by 512.

Similarly, in the assist pressure increasing state, the hydraulic pressure passage 534 and the wheel cylinder 122 of the left front wheel FL and the wheel cylinder 124 of the right rear wheel RR are maintained in a conductive state, and the hydraulic pressure passage 534 is Internal pressure is constant pressure release valve 54
Until the valve opening pressure exceeds 2 and the pressure becomes higher than the master cylinder pressure PM _{/ C} , the flow of fluid from the hydraulic passage 534 to the master cylinder 402 is blocked by the SMC- ₂ 514.

For this reason, when the assist pressure increasing state shown in FIG. 32 is realized, thereafter, the wheel cylinder pressure P _{W / C} of each wheel is increased by using the first pump 560 or the second pump 562 as a hydraulic pressure source. The pressure is quickly increased to a pressure exceeding the master cylinder pressure PM _{/ C.} Thus, according to the assist pressure increasing state shown in FIG. 32, the braking force can be quickly raised.

Incidentally, in the assist pressure increasing state shown in FIG. 32, the hydraulic pressure passages 518, 522, 528, 530
Is connected to the master cylinder 40 via the check valves 544 and 546.
It communicates with 2. Therefore, the master cylinder pressure P _{M / C}
If it is larger than the wheel cylinder pressure P _{W / C} of each wheel can boost the wheel cylinder pressure P _{W / C} as a fluid pressure source to the master cylinder 402. In BA operating state.

FIG. 33 shows an assist pressure holding state realized during execution of the BA control. The assist pressure holding state is B
This is realized when it is necessary to hold the wheel cylinder pressure P _{W / C} of each wheel during the execution of the A control, that is, when the (IV) assist pressure holding mode is required during the BA control. The assist pressure holding state is realized by turning on the master cut solenoids SMC- ₁ 512 and SMC- ₂ 514 as shown in FIG.

In the assist pressure holding state shown in FIG. 33, the first pump 560, the reservoir tank 408, and the second pump
Pump 562 and reservoir tank 408 are
It is shut off by C _-1 504 and SRC _-2 506. For this reason, in the assist pressure holding state, the first pump 560 and the second pump
No fluid is discharged to 34. In the assist pressure holding state shown in FIG. 33, hydraulic passages 518, 522 and 530, 534 are respectively connected to SMC- ₁ 512 and SM
It is substantially separated from the master cylinder 402 by C- ₂ 514. For this reason, according to the assist pressure holding state shown in FIG.
_{W / C} can be kept constant.

FIG. 34 shows a reduced assist pressure state realized during execution of the BA control. The assist pressure reduction state is B
When it is necessary to reduce the wheel cylinder pressure P _{W / C} of each wheel during the execution of the A control, that is, during the BA control, (III)
This is realized when execution of the assist pressure reduction mode and the (VI) assist pressure gradual reduction mode are requested. The assist pressure reduction state is realized by turning off all the solenoids as shown in FIG.

In the assist pressure reducing state shown in FIG. 34, the first pump 560 and the second pump 562 are disconnected from the reservoir tank 408. Therefore, the first pump 56
From the second and second pumps 562 to the hydraulic passages 522, 534
Fluid is not ejected. Further, in the assist pressure reduced state, the wheel cylinders 120 to 126 of each wheel and the master cylinder 402 are in a conductive state. Therefore, when the assist pressure reduction state is realized, 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.

In this embodiment, when the driver performs an emergency brake operation, the ECU 10 increases the assist pressure increasing state shown in FIGS. 32 to 34 in the same manner as in the first embodiment. The BA function is realized by combining the assist pressure holding state and the assist pressure decreasing state.
For this reason, according to the braking force control device of the present embodiment, when the driver performs an emergency braking operation, the driver is immediately swiftly operated in the same manner as in the above-described first and second embodiments. Generating the intended braking force; and
The driver's intention can be reflected in the braking force during the execution of the BA control.

In the braking force control apparatus of the present embodiment, when the above-described BA control is started, the wheel cylinder pressure P _{W / C of} each wheel is immediately increased, so that any one of the wheels becomes excessive. A high slip ratio may occur. In such a case, the ECU 10 determines that BA + ABS
Start control. Hereinafter, the operation of the braking force control device accompanying the BA + ABS control will be described with reference to FIGS.

The braking force control device according to the present embodiment is configured as follows: BA + AB
After the S control is started, the driver increases the braking force.
When the intended brake operation is performed, the ABS target wheel
Wheel cylinder pressure P_{W / C}To the pressure according to the ABS control request.
While controlling the wheel cylinder pressure P of the other wheels._{W / C}of
Increase. FIG. 35 shows that the right rear wheel RL is the ABS target wheel.
Performs the above functions during execution of BA + ABS control
(Hereinafter referred to as assist pressure increase (ABS)
State). Assist pressure increase (ABS) state
Is the second reservoir cut solenoid SRC_-2506, oh
And master cut solenoid SMC_-1512, SMC
_-2514 is turned on, the first pump 560 and the second pump
Turn on pump 562 and hold right rear wheel RL
Solenoid SRLH110 and pressure reducing solenoid SRL
R118 should be controlled appropriately according to ABS control requirements
Is realized.

In the assist pressure increasing (ABS) state,
The brake fluid discharged from the second pump 462 is supplied to the wheel cylinder 122 of the left front wheel FL and the wheel cylinder 124 of the right rear wheel RR as in the case of the assist pressure increasing state shown in FIG. Therefore, when the assist pressure increasing (ABS) state is realized, the wheel cylinder pressure P _{W / C} of these wheels FL and RR becomes similar to the case where the assist pressure increasing state is realized during the BA control. It is boosted.

BA + with left rear wheel RL as ABS target wheel
The ABS control is started by executing (ii) the pressure reduction mode for the left rear wheel RL. Accordingly, the brake fluid flows into the first reservoir 552 at the same time when the BA + ABS control is started. In the assist pressure increasing (ABS) state shown in FIG. 35, the first pump 560 sucks and pumps the brake fluid thus flowing into the first reservoir 552.

The brake fluid pumped by the first pump 560 mainly includes the wheel cylinder 12 of the right front wheel FR.
0 and is supplied to the wheel cylinder 126 when the (i) pressure increase mode is executed for the left rear wheel RL. According to the above control, the wheel cylinder pressure P _{W / C} of the right front wheel FR is increased in the same manner as when the assist pressure increasing state is realized during the BA control, and the wheel cylinder pressure P _{W of} the left rear wheel RL is increased. _{W / C} can be controlled to an appropriate value that does not cause an excessive slip ratio on the left rear wheel RL.

As described above, according to the assist pressure increasing (ABS) state shown in FIG. 35, the wheel cylinder pressure P _{W / C} of the left rear wheel RL, which is the ABS target wheel, is reduced to a pressure according to the request of the ABS control. While controlling, the wheel cylinder pressures P _{W / C} of the left and right front wheels FL, FR and the right rear wheel RR, which are not subject to the ABS control, are quickly changed in the same manner as when the assist pressure increase state is realized during the BA control. Can be increased.

The braking force control device according to the present embodiment is configured as follows: BA + AB
After the S control is started, when the driver performs a brake operation intended to maintain the braking force, the wheel cylinder pressure P _{W / C} of the ABS target wheel is controlled to a pressure according to the request of the ABS control, The wheel cylinder pressure P _{W / C} of the other wheels is maintained. FIG. 36 shows a state (hereinafter referred to as “assist pressure holding (ABS)”) that is realized to perform the above-described function during execution of the BA + ABS control using the right rear wheel RL as the ABS target wheel.
State). The assist pressure holding (ABS) state is determined by the master cut solenoid SMC _- 1512, SMC- _2.
514, the first pump 560 and the second pump 562 are turned on, the holding solenoid SFRH104 of the right front wheel FR is turned on, and the holding solenoid SRLH110 and the pressure reducing solenoid S of the left rear wheel RL are turned on.
This is realized by appropriately controlling the RLR 118 in response to a request for ABS control.

In the assist pressure holding (ABS) state,
The second pump 562 is shut off from the reservoir tank 408 as in the case where the assist pressure holding state shown in FIG. 33 is realized. The hydraulic passages 530 and 534 are substantially shut off from the master cylinder 402 as in the case where the assist pressure holding state shown in FIG. 33 is realized. Therefore, when the assist pressure holding (ABS) state is realized, the wheel cylinder pressure P of the left front wheel FL and the right rear wheel RR is increased.
_{W / C} is maintained at a constant value as in the case where the assist pressure holding state is realized during BA control.

In the first reservoir 552, at the same time that the assist pressure holding (ABS) state is realized or before the assist pressure holding (ABS) state is realized, the brake fluid flowing out of the wheel cylinder 126 is supplied. It is stored. The first pump 560 holds the assist pressure (AB
S) While the state is being realized, the brake fluid stored in the first reservoir 552 is sucked and pumped.

In the assist pressure holding state, the right front wheel FR
Is separated from the first pump 560 by the SFRH 104. Therefore, the first
The brake fluid pumped by the pump 560
It is supplied only to the wheel cylinder 126 of the left rear wheel RL.
Further, the inflow of brake fluid from the first pump 560 to the wheel cylinder 126 is permitted only when the (i) pressure increase mode is performed on the left rear wheel RL. According to the above-mentioned process, the wheel cylinder pressure P _{W / C} of the front right wheel FR is maintained at a constant value, the wheel cylinder pressure P _{W / C} of the rear left wheel RL is, an excessive slip rate in the front left wheel FL It is controlled to an appropriate pressure that does not occur.

As described above, according to the assist pressure increasing (ABS) state shown in FIG. 36, the wheel cylinder pressure P _{W / C} of the left rear wheel RL, which is the ABS target wheel, is appropriately adjusted according to the request of the ABS control. While controlling the pressure, the wheel cylinder pressures P _{W / C} of the left and right front wheels FL and FR and the right rear wheel RR, which are not subject to the ABS control, are controlled in the same manner as when the assist pressure holding state is realized during the BA control. It can be kept at a constant value.

[0283] The braking force control device according to the present embodiment is composed of BA + AB.
After the S control is started, when the driver performs a brake operation intended to reduce the braking force, the wheel cylinder pressure P _{W / C} of the ABS target wheel is controlled to a pressure according to the request of the ABS control, Reduce the wheel cylinder pressure P _{W / C} of the other wheels. The above-described function realizes the assist pressure reduction state shown in FIG.
According to the request of the ABS control, the holding solenoid S ** H and the pressure reducing solenoid S ** R are appropriately set so that (i) the pressure increasing mode, (ii) the holding mode, and (iii) the pressure reducing mode are realized.
Is realized by controlling Hereinafter, a state in which such control is being performed is referred to as an assist pressure reduction (ABS) state.

That is, when the assist pressure reduction (ABS) state is realized, all the holding solenoids S ** H
Communicates with the master cylinder 402. Therefore, when the assist pressure reduction (ABS) control is realized, the wheel cylinder pressure P _{W / C} of the wheel not controlled by the ABS control can be reduced using the master cylinder pressure P _{M / C} as a lower limit.
In addition, the wheel cylinder pressure P _{W / C} can be held or reduced for the target wheel of the ABS control by realizing the (ii) holding mode and (iii) the pressure reducing mode.

By the way, the assist pressure reduction (ABS) state is set when the driver intends to reduce the braking force, that is, when it is not necessary to increase the wheel cylinder pressure P _{W / C of} any wheel. Is achieved. Therefore, if the (ii) holding mode and (iii) the decompression mode can be realized as described above, the wheel cylinder pressure P _{W / C} of the ABS target wheel is appropriately controlled to the pressure required by the BA + ABS control. can do.

As described above, the assist pressure reduction (A
According to the BS) state, while controlling the wheel cylinder pressure P _{W / C} of the ABS target wheel to an appropriate pressure according to the request of the ABS control, the right front wheel FR and the left and right rear wheels RL which are not the target wheels of the ABS control. , RR wheel cylinder pressure P _{W / C} , B
As in the case where the assist pressure reduction state is realized during the A control, the pressure can be reduced using the master cylinder pressure P _{M / C} as the lower limit.

As described above, according to the braking force control apparatus of the present embodiment, when an excessive slip ratio occurs in any of the wheels after the BA control is started, the wheel cylinder pressure P of the ABS target wheel is increased. _The ABS function for suppressing the _{W / C} to an appropriate pressure required by the ABS control, and the wheel cylinder pressure P _{W / C} of the wheel not controlled by the ABS control is set to a higher pressure than the master cylinder pressure PM _{/ C.} In the region, the BA function of increasing or decreasing according to the driver's brake operation can be realized at the same time.

In the above-described embodiment, the type of the braking force control device is limited to the hydro booster type and the pump-up type. However, the present invention is not limited to this, and the present invention is not limited to this. When a vacuum booster with a variable power ratio is used, the present invention can be applied to a vacuum booster type braking force control device.

[0289]

As described above, according to the first aspect of the present invention, when an emergency braking operation is performed by a driver, a larger braking oil pressure is generated as compared with a normal time, and the braking oil pressure is increased. Adjustment can be performed according to the driver's intention while maintaining the pressure at a level larger than the case.

According to the second aspect of the present invention, the state to be realized by the brake hydraulic control mechanism is selected based on the deviation between the actual brake operation amount and the start operation amount, thereby setting the state of the brake hydraulic control mechanism. Can be appropriately reflected in the braking hydraulic pressure after the brake operation is newly switched. According to the third aspect of the present invention, the driver's intention can be appropriately reflected in the brake hydraulic pressure by selecting the state to be realized by the brake hydraulic control mechanism based on the brake operation speed.

According to the fourth aspect of the present invention, the intention of the driver can be appropriately reflected in the brake hydraulic pressure based on the deviation between the actual brake operation amount and the start operation amount and the brake operation speed. . According to the fifth aspect of the present invention, the intention of the driver at the time when the increase of the brake hydraulic pressure by the start pressure increasing means is completed can be accurately reflected on the brake hydraulic pressure.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram showing a normal braking state of a braking force control device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a hydro booster used in the braking force control device shown in FIG.

FIG. 3 is a diagram illustrating an ABS operation state of the braking force control device according to the first embodiment of the present invention.

FIG. 4 is a diagram showing an assist pressure increasing state realized during BA control or BA + ABS control in the braking force control device according to the first embodiment of the present invention.

FIG. 5 is a diagram showing an assist pressure holding state realized during BA control or BA + ABS control in the braking force control device according to the first embodiment of the present invention.

FIG. 6 is a diagram showing a reduced assist pressure state realized during BA control or BA + ABS control in the braking force control device according to the first embodiment of the present invention.

FIG. 7A corresponds to a first embodiment of the present invention.
When an emergency brake operation is performed by the braking force control device
Master cylinder pressure P_{M / C}Change rate ΔP_{M / C}Born in
FIG. FIG. 7B shows a first embodiment of the present invention.
Emergency braking operation in the braking force control device corresponding to the embodiment
Master cylinder pressure P_{M / C}And Hui
Cylinder pressure P _{W / C}FIG. 7 is a diagram showing a change that occurs in the first embodiment.

FIG. 8 is a flowchart of an example of a control routine executed to determine whether a first standby state is established in the braking force control device according to the first embodiment of the present invention.

FIG. 9 is a flowchart of an example of a control routine executed to determine whether a second standby state is established in the braking force control device according to the first embodiment of the present invention.

FIG. 10 shows an example of a control routine executed in the braking force control device according to the first embodiment of the present invention to determine whether a BA control start condition is satisfied and to calculate a pressure increase time in a start pressure increase mode. It is a flowchart of FIG.

11 is an example of a map of a reference pressure increase time T _STA0 referred to in the control routine shown in FIG. 10;

FIG. 12 is a flowchart (part 1) of an example of a control routine executed to realize BA control in the braking force control device according to the first embodiment of the present invention.

FIG. 13 is a flowchart (part 2) of an example of a control routine executed to realize BA control in the braking force control device according to the first embodiment of the present invention.

FIG. 14 is a flowchart (part 3) of an example of a control routine executed to realize BA control in the braking force control device according to the first embodiment of the present invention.

FIG. 15 is a flowchart (part 4) of an example of a control routine executed to realize BA control in the braking force control device according to the first embodiment of the present invention.

FIG. 16 is a flowchart (part 5) of one example of a control routine executed to realize BA control in the braking force control device according to the first embodiment of the present invention.

FIG. 17 is a flowchart (part 6) of an example of a control routine executed to realize BA control in the braking force control device according to the first embodiment of the present invention.

FIG. 18 is a flowchart (part 7) of an example of a control routine executed to realize BA control in the braking force control device according to the first embodiment of the present invention.

FIG. 19 is a table showing a control mode executed after the start pressure increase mode when BA control is executed in the braking force control device according to the first embodiment of the present invention.

FIG. 20 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 according to the first embodiment of the present invention.

FIG. 21 is a table showing a control mode executed next to the assist pressure reduction mode when BA control is executed in the braking force control device according to the first embodiment of the present invention.

FIG. 22 is a table showing a control mode executed next to the assist pressure holding mode when the BA control is executed in the braking force control device according to the first embodiment of the present invention.

FIG. 23 is a table showing a control mode executed next to the assist pressure gradual increase mode when BA control is executed in the braking force control device according to the first embodiment of the present invention.

FIG. 24 is a table showing a control mode executed next to the assist pressure gradual decrease mode when BA control is executed in the braking force control device according to the first embodiment of the present invention.

FIG. 25 is a system configuration diagram showing a normal braking state and an ABS operation state of the braking force control device according to the second embodiment of the present invention.

FIG. 26 is a diagram showing an assist pressure increasing state realized during the BA control in the braking force control device according to the second embodiment of the present invention.

FIG. 27 is a diagram showing an assist pressure holding state realized during BA control in the braking force control device according to the second embodiment of the present invention.

FIG. 28 is a diagram showing a reduced assist pressure state realized during BA control or BA + ABS control in the braking force control device according to the second embodiment of the present invention.

FIG. 29 is a diagram showing an assist pressure increasing state realized during BA + ABS control in the braking force control device according to the second embodiment of the present invention.

FIG. 30 is a diagram showing an assist pressure holding state realized during BA + ABS control in the braking force control device according to the second embodiment of the present invention.

FIG. 31 is a system configuration diagram showing a normal braking state and an ABS operation state of the braking force control device according to the third embodiment of the present invention.

FIG. 32 is a diagram showing an assist pressure increasing state realized during BA control in the braking force control device according to the third embodiment of the present invention.

FIG. 33 is a diagram showing an assist pressure holding state realized during BA control in the braking force control device according to the third embodiment of the present invention.

FIG. 34 is a diagram showing a reduced assist pressure state realized during BA control or BA + ABS control in the braking force control device according to the third embodiment of the present invention.

FIG. 35 is a diagram showing an assist pressure increasing state realized during BA + ABS control in the braking force control device according to the third embodiment of the present invention.

FIG. 36 is a diagram showing an assist pressure holding state realized during BA + ABS control in the braking force control device according to the third embodiment of the present invention.

[Explanation of symbols]

10 Electronic Control Unit (ECU) 12 Brake Pedal 36 Hydro Booster 86 First Assist Solenoid (SA- ₁ ) 88 Second Assist Solenoid (SA- ₂ ) 90 Third Assist Solenoid (SA- ₃ ) 94 Regulator Switching Solenoid (STR) 104, 106, 108, 110 Holding solenoid (S
** H) 112, 114, 116, 118 Decompression solenoid (S
** R) 120, 122, 124, 126 Wheel cylinder 144 Hydraulic pressure sensor 400 Vacuum booster 402 Master cylinder 414 Front reservoir cut solenoid (SRC
F) 416 Rear reservoir cut solenoid (SRCR) 426 Right front master cut solenoid (SMFR) 428 Left front master cut solenoid (SMFL) 430 Rear master cut solenoid (SMR) 460 Front pump 462 Rear pump 504 1st reservoir cut solenoid (SRC _-1 ) 506 Second reservoir cut solenoid (SRC _-2 ) 512 First master cut solenoid (SMC _-1 ) 514 Second master cut solenoid (SMC _-2 ) 560 First pump 562 Second pump

Claims (5)

[Claims] An assist pressure increasing state for increasing a braking oil pressure independently of a braking operation in a braking force control device that generates a larger braking oil pressure than usual when an emergency braking operation is performed by a driver. And a brake hydraulic pressure control mechanism that realizes an assist pressure holding state that holds the brake hydraulic pressure regardless of the brake operation, and an assist pressure reducing state that reduces the brake hydraulic pressure regardless of the brake operation. Emergency brake operation detecting means for detecting execution of an emergency brake operation; and when the emergency brake operation is detected, the brake hydraulic control mechanism is set to the assist pressure increasing state to generate a larger brake hydraulic pressure than normal. Start pressure increasing means, and after the braking oil pressure is increased by the start pressure increasing means,
The assist pressure increasing state according to the state of the brake operation,
A braking force control device comprising: a braking oil pressure adjusting unit that adjusts a braking oil pressure by switching between the assist pressure holding state and the assist pressure decreasing state. 2. The braking force control device according to claim 1, further comprising: a starting operation amount detecting unit that detects a braking operation amount when the state of the braking hydraulic control mechanism changes as a starting operation amount. The brake hydraulic pressure adjusting means includes first control state selecting means for selecting a state to be realized by the brake hydraulic control mechanism based on a deviation between an actual brake operation amount and the starting operation amount. Braking force control device. 3. The braking force control device according to claim 1, wherein the braking oil pressure adjusting means selects a state to be realized by the braking oil pressure control mechanism based on a brake operation speed.
A braking force control device comprising: a control state selecting means. 4. The braking force control device according to claim 1, further comprising: a start operation amount detection unit that detects a brake operation amount when the state of the brake hydraulic control mechanism changes as a start operation amount. A third control state selection unit that selects a state to be realized by the brake hydraulic control mechanism based on a deviation between an actual brake operation amount and the start operation amount and a brake operation speed; When the absolute value of the deviation is equal to or greater than a predetermined value, and when the absolute value of the brake operation speed is equal to or greater than a predetermined speed, the pressure increasing / decreasing gradient that makes the pressure increasing / decreasing gradient of the brake hydraulic pressure steeper than in other cases. And a changing unit. 5. The braking force control device according to claim 1, wherein the braking oil pressure adjusting means sets a state to be realized by the braking oil pressure control mechanism after the increase of the braking oil pressure by the start pressure increasing means is completed. A braking force control device comprising: a fourth control state selecting means for selecting based on a brake operation speed at the time when the increase of the brake hydraulic pressure by the start pressure increasing means is completed.