JP2003160039A - Vehicle brake controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the braking force of an entire vehicle from getting insufficient without impairing front-rear wheel distribution control. <P>SOLUTION: In the case that front-rear wheel braking force distribution control is not conducted (S20), holding pressure Pc is calculated based on a vehicle speed V and a vehicle deceleration Gxb (S50 to S70), when a starting condition of the front-rear wheel distribution control is satisfied (S60, S70), based on a deviation Pm-Pc of master cylinder pressure Pm and the holding pressure Pc of rear wheels and a brake effect coefficient BEFv corresponding to a current vehicle speed, the increasing pressure ΔPf of braking pressure of front wheels corresponding to a shortage of braking pressure of rear wheels because the braking pressure of the rear wheels is maintained by the holding pressure Pc (S110), a front wheel system of a control device 10 is controlled so that the braking pressure of right and left front wheels becomes equal to a target braking force calculated by adding the master cylinder pressure Pm and the increasing pressure ΔPf (S120), a rear wheel system of a braking device 10 is controlled so that the braking pressure of right and left rear wheels becomes equal to the holding pressure Pc (S130). <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a braking control device for a vehicle such as an automobile, and more particularly to a braking control device for a vehicle that controls the distribution of braking force between front and rear wheels.

[0002]

2. Description of the Related Art As one of braking control devices for a vehicle such as an automobile, the driving state of the vehicle is set to a predetermined state in order to prevent the rear wheels from locking during braking of the vehicle and improve the running stability of the vehicle. Conventionally, there has been known a braking control device configured to hold or reduce the braking pressure of the rear wheels or to increase the pulse pressure to perform front and rear wheel braking force distribution control that suppresses an increase in the braking force of the rear wheels.

According to this type of braking control device, the rear wheels are in a locked state prior to the front wheels as compared with the case where the front and rear wheel braking force distribution control is not carried out. It is possible to prevent the stability of the vehicle from deteriorating and improve the running stability of the vehicle, but when the front and rear wheel braking force distribution control is executed, an increase in the braking force of the rear wheels is suppressed.
Even if the driver tries to increase the braking force and increases the amount of braking operation, the braking force of the entire vehicle does not sufficiently increase, and the driver may feel uncomfortable in the braking operation.

In order to solve such a problem, for example, Japanese Patent Application Laid-Open No. 2001-219834 filed by the applicant of the present application determines the amount of braking operation of the driver, and the driving state of the vehicle becomes a predetermined state. A braking control device configured to increase the braking force of the rear wheels when it is determined that the braking operation amount of the driver is increasing in the situation where the braking force distribution control is executed is described. .

[0005]

According to the braking control device disclosed in the above publication, when the braking operation amount of the driver is increased in the situation where the front and rear wheel braking force distribution control is executed. Since the braking force of the rear wheels is increased, the driver does not sufficiently increase the braking force as a whole even if the driver increases the braking operation amount to increase the braking force. It is possible to reduce the possibility of feeling uncomfortable.

However, since the range of increase of the braking force allowed to the rear wheels is limited, in the above-described braking control device, the rear wheels are locked prior to the front wheels, and There is a problem that the braking force of the vehicle as a whole cannot be sufficiently increased while reliably preventing the deterioration of the stability of the vehicle.

The present invention has the above-mentioned problem in the conventional braking control device configured to perform the front and rear wheel braking force distribution control for suppressing the increase of the braking force of the rear wheels when the driving state of the vehicle reaches a predetermined state. In view of the above, the main problem of the present invention is to reduce the shortage of the braking force of the rear wheels by suppressing the increase of the braking force of the rear wheels by the front and rear wheel braking force distribution control. To prevent the braking force of the entire vehicle from becoming insufficient without impairing the front / rear wheel distribution control, that is, the rear wheels are locked before the front wheels, and That is, the braking force of the vehicle as a whole is set to a value according to the amount of braking operation by the driver while surely preventing the stability of the vehicle from being deteriorated.

[0008]

According to the present invention, the above-mentioned main problem is that the braking force generating device according to the first aspect of the present invention, that is, a braking force generating device provided with hydraulic fluid pressure of a master cylinder corresponding to each wheel is used. A braking control device for a vehicle, which generates front and rear wheel braking force distribution control for generating a braking force by supplying the braking force to the wheel cylinders and suppressing an increase in the braking force of the rear wheels when the operating state of the vehicle reaches a predetermined state, Achieved by a vehicle braking control device characterized in that it has front wheel braking force increasing means for increasing the braking force of the front wheels in accordance with the amount of increase suppression of the braking force of the rear wheels when the front and rear wheel braking force distribution control is being performed. To be done.

Further, according to the present invention, in order to effectively achieve the above-mentioned main problem, in the structure of claim 1, the front-rear wheel braking force distribution control increases the wheel cylinder pressure of the rear wheels. The front wheel braking force increasing means controls the front wheel based on the amount of braking operation by the driver, the wheel cylinder pressure of the rear wheel, and the parameter indicating the braking performance of the braking force generators for the front and rear wheels. The wheel cylinder pressure increase amount is calculated, and the wheel cylinder pressure of the front wheel is increased based on the increase amount (claim 2).
Configuration).

Further, according to the present invention, in order to effectively achieve the above-mentioned main problem, in the configuration of the above-mentioned claim 2, the parameter is a parameter that indicates a lower braking performance as the vehicle speed increases. (Claim 3).

[0011]

According to the constitution of the above-mentioned claim 1,
When the front / rear wheel braking force distribution control is being performed, the front wheel braking force is increased according to the amount by which the increase in the rear wheel braking force is suppressed, so the front and rear wheel braking force distribution control is performed and the rear wheel braking force is increased. It is possible to reliably compensate for the shortage of the braking force of the rear wheels due to the suppression of the braking force by increasing the braking force of the front wheels, so that the rear wheels are locked prior to the front wheels and As a result, the braking force of the entire vehicle can be effectively controlled to a braking force according to the braking operation amount of the driver while reliably preventing the deterioration of the stability of the vehicle.

According to the second aspect of the invention, the braking operation amount by the driver, the wheel cylinder pressure of the rear wheel,
The wheel cylinder pressure increase amount of the front wheels is calculated based on the parameter indicating the braking performance of the braking force generating device for the front wheels and the rear wheels, and the wheel cylinder pressure of the front wheels is increased based on the increase amount. By increasing the braking force of the front wheels by increasing the braking force of the front wheels by suppressing the increase in pressure, the wheel cylinder pressure of the front wheels is increased to ensure that the braking force of the entire vehicle is operated. The braking force can be controlled according to the braking operation amount of the person.

Generally, the braking performance of the braking force generator that generates the braking force by supplying the hydraulic fluid of the master cylinder to the wheel cylinders decreases as the vehicle speed increases. It is preferable that the parameter representing the braking performance of the braking force generators for the front wheels and the rear wheels used when calculating the wheel cylinder pressure increase amount is a parameter representing a lower braking performance of the braking force generator as the vehicle speed increases.

According to the structure of claim 3, the wheel cylinder pressure increase amount of the front wheels is equal to the braking operation amount by the driver,
It is calculated based on the wheel cylinder pressures of the rear wheels and the parameters representing the braking performance of the braking force generators for the front and rear wheels.The parameter in that case is a parameter that represents a lower braking performance as the vehicle speed increases, so the vehicle speed is It is possible to calculate the wheel cylinder pressure increase amount of the front wheels in consideration of the braking performance of the braking force generator that decreases as it increases, and thereby the wheel cylinder pressure of the front wheels can be appropriately increased regardless of the vehicle speed.

[0015]

According to one preferred aspect of the present invention, in the above-mentioned structure of the first aspect, the braking control device controls the vehicle speed at the time when the operating state of the vehicle reaches a predetermined state. Accordingly, the increase suppression amount of the braking force of the rear wheels is variably set (preferred aspect 1).

According to another preferred aspect of the present invention, in the structure of claim 1, the braking control device controls the deceleration of the vehicle at the time when the operating state of the vehicle reaches a predetermined state. Accordingly, the increase suppression amount of the braking force of the rear wheels is variably set (preferred aspect 2).

According to another preferred aspect of the present invention, in the structure of claim 2, the front wheel braking force increasing means has a deviation between the master cylinder pressure and the wheel cylinder pressure of the rear wheel, and the front wheel and the rear wheel. It is configured to calculate the wheel cylinder pressure increase amount of the front wheel based on the parameter representing the braking performance of the wheel braking force generation device (preferred aspect 3).

According to another preferred aspect of the present invention, in the structure of claim 2, the braking control device sets the running state of the vehicle at the time when the operating state of the vehicle reaches a predetermined state. Accordingly, the holding pressure of the rear wheels is set, and the braking pressure of the rear wheels is maintained at the holding pressure (preferred aspect 4).

According to another preferred aspect of the present invention, in the structure of the above-mentioned claim 2, the braking control device controls the master cylinder pressure at the time when the operating condition of the vehicle reaches a predetermined condition. The holding pressure of the wheels is set, and the braking pressure of the rear wheels is maintained at the holding pressure (preferred aspect 5).

According to another preferred aspect of the present invention, in the configuration of claim 3, the parameter is configured to include a braking effectiveness coefficient of the braking force generator (preferred aspect 6).

According to another preferred embodiment of the present invention, in the structure of claim 3, the braking effectiveness coefficient is estimated based on the vehicle speed (preferred embodiment 7).

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic configuration diagram showing a hydraulic circuit and an electronic control unit of one embodiment of a braking control device according to the present invention, and FIG. 2 is a schematic diagram showing a communication control valve for front wheels shown in FIG. FIG. In FIG. 1, the solenoid of each valve that is electromagnetically driven is not shown.

In FIG. 1, reference numeral 10 denotes a hydraulic braking device. The braking device 10 has a master cylinder 14 for pumping brake oil in response to a driver's depression of a brake pedal 12. There is. Master cylinder 1
Reference numeral 4 has a first master cylinder chamber 14A and a second master cylinder chamber 14B defined by a free piston 16 biased to a predetermined position by compression coil springs on both sides thereof.

One end of the brake hydraulic pressure control conduit 18F for the front wheels is connected to the first master cylinder chamber 14A, and the other end of the brake hydraulic pressure control conduit 18F is connected to the brake hydraulic pressure control conduit 20FL for the left front wheel and the right front wheel. One end of the brake hydraulic pressure control conduit 20FR is connected. A communication control valve 22F for the front wheels is provided in the middle of the brake hydraulic pressure control conduit 18F, and the communication control valve 22F is a normally open linear solenoid valve in the illustrated embodiment. Communication control valve 22
A non-return bypass conduit 24F that allows only the flow of oil from the first master cylinder chamber 14A to the brake hydraulic pressure control conduit 20FL or the brake hydraulic pressure control conduit 20FR is connected to the brake hydraulic pressure control conduits 18F on both sides of F.

As shown schematically in FIG. 2, the communication control valve 22F has a housing 7 which defines a valve chamber 70 therein.
2 and a valve element 74 is reciprocally arranged in the valve chamber 70. The valve chamber 70 has a brake hydraulic pressure control conduit 18F.
The portion 18FA of the master cylinder 14 side of the internal passage 7
A portion 18F of the brake hydraulic pressure control conduit 18F on the opposite side of the master cylinder 14 which is always connected and communicated via 6
B is communicatively connected via an internal passage 78 and a port 80.

As shown, a solenoid 82 is disposed around the valve element 74, and the valve element 74 is biased by the compression coil spring 84 to the valve open position shown in FIG. When a drive voltage is applied to the solenoid 82, the valve element 74 resists the spring force of the compression coil spring 84 and the port 80.
Urging against, thereby closing the port 80 by closing it.

Further, when the communication control valve 22F is in the closed position, the force due to the pressure in the portion 18FB of the brake hydraulic pressure control conduit 18F on the side opposite to the master cylinder 14 and the spring force of the compression coil spring 84. Solenoid 82 in total
When the electromagnetic force is higher than the electromagnetic force by
The port in the portion 18FB is opened away from 0, and the oil in the portion 18FB is supplied to the internal passage 78, the port 80, the valve chamber 70, the internal passage 76
To the portion 18FA of the brake hydraulic pressure control conduit 18F. When the pressure of the oil in the portion 18FB decreases due to this oil flow, the total of the force due to the pressure and the spring force of the compression coil spring 84 becomes lower than the electromagnetic force due to the solenoid 82, and the valve element 74 causes the port 80 to move. Close it again.

Thus, since the communication control valve 22F controls the pressure in the portion 18FB of the brake hydraulic pressure control conduit 18F according to the voltage applied to the solenoid 82, the communication control valve 22F is controlled by controlling the drive voltage to the solenoid 82. The pressure within 18FB (herein referred to as "upstream pressure") can be controlled to a desired pressure.

In the illustrated embodiment, the non-return bypass conduit 24F shown in FIG. 1 is incorporated in the communication control valve 22F, and has an internal passage 86 and a valve chamber provided in the middle of the internal passage. The check valve 88 allows only the flow of oil from 70 toward the portion 18FB.

Brake hydraulic pressure control conduit 20FL for the left front wheel and brake hydraulic pressure control conduit 20FR for the right front wheel generate braking force for the left front wheel and the right front wheel, respectively, at the other ends thereof, which is not shown in FIG. Device wheel cylinder 26FL
And 26FR are connected, and the brake hydraulic pressure control conduit 20FL for the left front wheel and the brake hydraulic pressure control conduit 2 for the right front wheel are connected.
Normally open solenoid valves 28FL and 28FR are provided in the middle of 0FR. Electromagnetic on-off valves 28FL and 28FR
Non-return bypass conduits 30FL and 30FR which allow only the flow of oil from the wheel cylinders 26FL and 26FR to the brake oil pressure control conduit 18F are connected to the brake oil pressure control conduits 20FL and 20FR on both sides of the brake oil pressure control conduits 20FL and 20FR, respectively.

Electromagnetic on-off valve 28FL and wheel cylinder 26
One end of an oil discharge conduit 32FL is connected to the brake hydraulic pressure control conduit 20FL between the brake hydraulic pressure control conduit 20FL and the FL, and the brake hydraulic pressure control conduit 20 between the electromagnetic opening / closing valve 28FR and the wheel cylinder 26FR.
One end of an oil discharge conduit 32FR is connected to FR.
Normally closed solenoid valves 34FL and 34FR are provided in the middle of the oil discharge conduits 32FL and 32FR, respectively.
The other ends of the oil discharge conduits 32FL and 32FR are connected to the connecting conduit 36.
F is connected to the front wheel buffer reservoir 38F.

As can be seen from the above description, the solenoid opening / closing valve 28
FL and 28FR are wheel cylinders 26FL and 2 respectively.
A pressure increasing valve to increase or maintain the pressure in 6FR,
The electromagnetic opening / closing valves 34FL and 34FR are pressure reducing valves for reducing the pressure in the wheel cylinders 26FL and 26FR, respectively. Therefore, the electromagnetic opening / closing valves 28FL and 34FL cooperate with each other to increase or decrease the pressure in the wheel cylinder 26FL of the left front wheel. A pressure increasing / decreasing valve for holding the solenoid valve is defined.
8FR and 34FR cooperate with each other to define an increasing / decreasing valve for increasing / decreasing and maintaining the pressure in the wheel cylinder 26FR for the right front wheel.

The connection conduit 36F is connected to the suction side of the pump 42F by the connection conduit 40F, and the connection conduit 40F
Two check valves 44F and 46F which allow only the flow of oil from the connecting conduit 36F to the pump 42F are provided in the middle of the above. The discharge side of the pump 42F is connected to the brake hydraulic pressure control conduit 18F by a connection conduit 50F having a damper 48F on the way. Pump 42F and damper 4
A check valve 52F that allows only the flow of oil from the pump 42F toward the damper 48F in the connecting conduit 50F between the 8F and the 8F.
Is provided.

One end of the connecting conduit 54F is connected to the connecting conduit 40F between the two check valves 44F and 46F, and the other end of the connecting conduit 54F is connected to the first master cylinder chamber 1.
Brake hydraulic pressure control conduit 18 between 4A and control valve 22F
It is connected to F. A normally closed electromagnetic on-off valve 60F is provided in the middle of the connection conduit 54F. The electromagnetic opening / closing valve 60F functions as an intake control valve that controls communication between the brake hydraulic pressure control conduit 18F between the master cylinder 14 and the control valve 22F and the intake side of the pump 42F.

Similarly, one end of the brake hydraulic pressure control conduit 18R for the rear wheel is connected to the second master cylinder chamber 14B, and the other end of the brake hydraulic pressure control conduit 18R is connected to the brake hydraulic pressure control conduit 20RL for the left rear wheel. And one end of a brake hydraulic pressure control conduit 20RR for the right rear wheel is connected. A rear wheel communication control valve 22R, which is a normally open linear solenoid valve, is provided in the middle of the brake hydraulic pressure control conduit 18R.

The communication control valve 22R is the communication control valve 2 for the front wheels.
2F has the same structure as that shown in FIG. 2, and therefore, by controlling the drive voltage to the solenoid not shown in the figure, the brake hydraulic pressure control conduit 18R downstream of the communication control valve 22R is controlled. The internal pressure (upstream pressure) can be controlled to a desired pressure. Further, a check bypass conduit 24R which allows only the flow of oil from the second master cylinder chamber 14B to the brake hydraulic pressure control conduit 20RL or the brake hydraulic pressure control conduit 20RR is connected to the brake hydraulic pressure control conduits 18R on both sides of the communication control valve 22R. ing.

FIG. 1 shows that the other ends of the brake hydraulic pressure control conduit 20RL for the left rear wheel and the brake hydraulic pressure control conduit 20RR for the right rear wheel generate braking forces for the left rear wheel and the right rear wheel, respectively. Wheel cylinder of non-braking force generator 26RL
And 26RR are connected, and a brake hydraulic pressure control conduit 20RL for the left rear wheel and a brake hydraulic pressure control conduit 2 for the right rear wheel are connected.
Normally open solenoid valves 28RL and 28RR are provided in the middle of 0RR. Electromagnetic on-off valves 28RL and 28RR
Non-return bypass conduits 30RL and 30RR, which allow only the flow of oil from the wheel cylinders 26RL and 26RR to the brake oil pressure control conduit 18R, are connected to the brake oil pressure control conduits 20RL and 20RR on both sides of, respectively.

Electromagnetic on-off valve 28RL and wheel cylinder 26
One end of an oil discharge conduit 32RL is connected to the brake hydraulic pressure control conduit 20RL between the RL and the brake hydraulic pressure control conduit 20 between the electromagnetic opening / closing valve 28RR and the wheel cylinder 26RR.
One end of an oil discharge conduit 32RR is connected to RR.
Normally closed solenoid valves 34RL and 34RR are provided in the middle of the oil discharge conduits 32RL and 32RR, respectively.
The other ends of the oil discharge conduits 32RL and 32RR are connected to the connecting conduit 36.
It is connected to the rear wheel buffer reservoir 38R by R.

As in the case of the front wheels, the solenoid on-off valves 28RL and 28RR are wheel cylinders 26RL and 26RR, respectively.
Is a pressure increasing valve for increasing or maintaining the internal pressure, and the solenoid opening / closing valves 34RL and 34RR are respectively wheel cylinders 2
6RL and 26RR are pressure reducing valves for reducing the pressure, so that the solenoid opening / closing valves 28RL and 34RL cooperate with each other to form a pressure increasing / decreasing valve for increasing and decreasing the pressure in the left rear wheel cylinder 26RL. The solenoid on-off valve 28
RR and 34RR cooperate with each other to define a pressure increasing / decreasing valve for increasing / decreasing and maintaining the pressure in the wheel cylinder 26RR of the right rear wheel.

The connection conduit 36R is connected to the suction side of the pump 42R by the connection conduit 40R, and the connection conduit 40R
Two check valves 44R and 46R which allow only the flow of oil from the connecting conduit 36R to the pump 42R are provided in the middle of the above. The discharge side of the pump 42R is connected to the brake hydraulic pressure control conduit 18R by a connecting conduit 50R having a damper 48R on the way. Pump 42R and damper 4
A check valve 52R which allows only the flow of oil from the pump 42R to the damper 48R in the connecting conduit 50R between the 8R and the 8R.
Is provided. The pumps 42F and 42R are driven by a common electric motor not shown in FIG.

One end of the connecting conduit 54R is connected to the connecting conduit 40R between the two check valves 44R and 46R, and the other end of the connecting conduit 54R is connected to the second master cylinder chamber 1.
Brake hydraulic pressure control conduit 18 between 4B and control valve 22R
It is connected to R. A normally closed electromagnetic on-off valve 60R is provided in the middle of the connection conduit 54R. The solenoid opening / closing valve 60R also functions as an intake control valve that controls communication between the brake hydraulic pressure control conduit 18R between the master cylinder 14 and the control valve 22R and the intake side of the pump 42R.

In the illustrated embodiment, each control valve and each on-off valve is set to the non-control position shown in FIG. 1 when the corresponding solenoid is not energized with a drive current.
As a result, the pressure in the first master cylinder chamber 14A is supplied to the wheel cylinders 26FL and 26FR, and the pressure in the second master cylinder chamber 14B is supplied to the wheel cylinders 26RL and 26RR. Therefore, normally, the pressure in the wheel cylinder of each wheel, that is, the braking force is increased or decreased according to the pedaling force of the brake pedal 12.

On the other hand, the communication control valves 22F and 22R are switched to the closed positions, the open / close valves 60F and 60R are opened, and the open / close valves of the wheels are in the positions shown in FIG. , 42R are driven, the oil in the master cylinder 14 is pumped up by the pump, and the pressure pumped up by the pump 42F is supplied to the wheel cylinders 26FL, 26FR, so that the wheel cylinder 2
Since the pressure pumped up by the pump 42R is supplied to the 6RL and 26RR, the braking pressure of each wheel is irrespective of the pedaling force of the brake pedal 12 and the communication control valve 22.
It is increased / decreased by opening / closing F, 22R and the opening / closing valve (increase / decrease valve) of each wheel.

In this case, the pressure in the wheel cylinder is
The on-off valves 28FL to 28RR and the on-off valves 34FL to 34RR are shown in FIG.
In the non-control position shown in Fig. 1, the pressure is increased (pressure increase mode), the open / close valves 28FL to 28RR are switched to the closed position, and the open / close valves 34FL to 34RR are in the non-control position shown in Fig. 1. Hold (hold mode), open / close valve 28
When the FL to 28RR and the on-off valves 34FL to 34RR are switched to the valve open positions, the pressure is reduced (pressure reduction mode).

Communication control valves 22F and 22R, open / close valve 28
The FL to 28RR, the on-off valves 34FL to 34RR, and the on-off valves 60F and 60R are controlled by the electronic control unit 90 as described later. The electronic control unit 90 is the microcomputer 9
2 and a driving circuit 94, the microcomputer 92 may have a general structure well known in the art.

In the microcomputer 92, a signal indicating the master cylinder pressure Pm from the pressure sensor 96, a signal indicating the vehicle speed V from the vehicle speed sensor 98, and the longitudinal acceleration sensor 100.
Further, a signal indicating the longitudinal acceleration Gx of the vehicle is input. Further, the microcomputer 92 stores a braking control flow described later, and the target braking pressure Pti (i = fl, f) of the left and right front wheels and the left and right rear wheels is stored according to the braking control flow.
(r, rl, rr) and braking pressure Pi (i = fl, fr, r) of each wheel by controlling the communication control valve 22F and the like.
l, rr) are controlled to the corresponding target braking pressures Pti.

Particularly in the illustrated embodiment, when the amount of braking operation by the driver is small and the front / rear distribution control of the braking force is unnecessary, the communication control valve 22F and the like are maintained at the illustrated standard position and the pumps 42F and 42R are maintained. Is not driven, so that the braking pressure of each wheel, that is, the wheel cylinders 26FL-2FL
The pressure in 626RR is controlled by the master cylinder pressure Pm.

On the other hand, when the amount of braking operation by the driver is large and the front / rear distribution control of the braking force is required, first the communication control valves 22F and 22R are closed, and then the suction control valves 60F and 60R are opened. Later pump 42F
And 42R are started, the rear wheel holding pressure Pc is calculated based on the vehicle speed V and the vehicle deceleration Gxb (= -Gx), and the master cylinder pressure Pm and the rear wheel holding are calculated as will be described later in detail. The increased pressure ΔPf of the front wheels is calculated based on the pressure Pc and the like, and the communication control valve 22F is controlled to control the front wheel system so that the upstream pressure on the front wheel side becomes the target braking pressure of Pm + ΔPf, and the open / close valves for the left and right rear wheels By closing the valves 28RL and 28RR, the rear wheel system is controlled so that the braking pressure of the left and right rear wheels becomes the holding pressure Pc.

Although not shown in the figure, the solenoid opening / closing valve 2
The 8FL to 28RR and the on-off valves 34FL to 34RR are controlled when the behavior of the vehicle is stabilized by individually controlling the braking force of each wheel, for example. In this case, in particular, the higher target braking pressure of the left and right wheels is set to the target upstream pressure Ptf, Ptr, and the target braking pressure Pti of the left and right wheels is increased by the communication control valve 22F or 22R. The pressure is controlled by controlling the target upstream pressure Ptf or Ptr, and the braking pressure of the wheels on the left and right sides is controlled to the corresponding target braking pressure by the corresponding pressure increasing valve and pressure reducing valve.

Next, the braking control routine in the illustrated embodiment will be described with reference to the flow chart shown in FIG. The control according to the flowchart shown in FIG. 3 is started by closing an ignition switch (not shown) and is repeatedly executed at predetermined time intervals.

First, in step 10, the pressure sensor 9
A signal or the like indicating the master cylinder pressure Pm detected in 6 is read, and it is determined in step 20 whether or not the braking force distribution control of the front and rear wheels is being performed, that is, affirmative in step 30 described later. After the determination is made, it is determined in step 40 whether or not the positive determination is not performed. When the positive determination is performed, the process proceeds to step 90, and the negative determination is performed. If so, go to step 30.

In step 30, the basic holding pressure Pcs of the rear wheels is calculated from the map corresponding to the graph shown in FIG. 4 based on the vehicle speed V, and in step 40, the basic holding pressure Pcs of the rear wheel is calculated based on the vehicle deceleration Gxb. The correction pressure ΔPc for the basic holding pressure Pcs is calculated from the map corresponding to the graph shown in FIG. 5, and in step 50 the rear wheel holding pressure Pc is calculated as the sum of the basic holding pressure Pcs and the correction pressure ΔPc. It Note that Gxbo in FIG. 5 is a standard vehicle deceleration during braking of the vehicle.

In step 60, it is judged whether the master cylinder pressure Pm exceeds the rear wheel holding pressure Pc,
That is, it is determined whether or not it is necessary to maintain the braking pressure of the rear wheels and increase the braking pressure of the front wheels. If a negative determination is made, the process proceeds to step 70, and if a positive determination is made, step 100 is performed. Go to.

In step 70, it is determined in accordance with any procedure known in the art whether or not other starting conditions for the front / rear wheel braking force distribution control are satisfied, and a negative determination is made. When the affirmative determination is made, the holding pressure Pc of the rear wheels is set to the master cylinder pressure Pm at that time, and the subsequent step is performed. 100
Go to.

Whether or not another starting condition for the front / rear wheel braking force distribution control is satisfied is determined by, for example, (A) the average value Vwr of the wheel speeds of the left and right rear wheels relative to the average value Vwf of the wheel speeds of the left and right front wheels. Deviation ΔVw of control start reference value Vws (positive constant)
Whether or not it is above, or (B) vehicle deceleration G
It may be performed by determining whether or not xb is equal to or larger than the control start reference value Gxs (a positive constant), or may be performed by a combination of the above (A) and (B).

In step 90, for example, by determining whether or not the master cylinder pressure Pm has become equal to or less than the control end reference value Pme (a positive constant smaller than Pc), the end condition for the front and rear wheel braking force distribution control is determined. It is determined whether or not is satisfied, and when the affirmative determination is performed, the control by the routine shown in FIG. 3 is temporarily terminated, and when the negative determination is performed, the process proceeds to step 100.

It should be noted that the determination as to whether or not the termination condition of the braking force distribution control for the front and rear wheels has been established may be performed in any manner known in the art, and for example, the determination of the establishment of the control start condition may be performed by the wheel. If it is performed based on the velocity deviation ΔVw,
The determination may be made by determining whether or not the wheel speed deviation ΔVw has become less than or equal to the control end reference value Vwe (a positive constant smaller than Vws), and whether or not the control start condition is satisfied is determined based on the vehicle deceleration Gxb. When it is performed, it may be determined by determining whether or not the deceleration Gxb of the vehicle is equal to or less than the control end reference value Gxe (a positive constant smaller than Gxs).

In step 100, the wheel cylinder cross-sectional areas of the front and rear wheels are set to Sf and Sr (positive constants), and the effective braking radii of the front and rear wheels are set to R, respectively.
The basic increasing pressure ΔPfo of the braking pressure of the front wheels is calculated according to the following formula 1 with f and Rr (positive constants) and the braking effectiveness coefficients of the front wheels and the rear wheels being BEFf and BEFr (positive constants), respectively. The wheel cylinder cross-sectional areas Sf and Sr and the effective braking radii Rf and Rr are values determined by the specifications of the braking force generator, and the braking effectiveness coefficients BEFf and BEFr are experimentally obtained in advance. ΔPfo = (Pm−Pc) (Sr × Rr × BEFr) / (Sf × Rf × BEFf) (1)

In step 110, the braking effectiveness coefficient BEFv corresponding to the current vehicle speed is calculated from the map corresponding to the graph shown in FIG. 6 based on the vehicle speed V, and the standard braking effectiveness coefficient BEFo and the current braking effectiveness are calculated. The deviation .DELTA.BEF (= BEFo-BEFv) from the coefficient BEFv is calculated, and further the increase pressure .DELTA.Pf of the braking pressure of the front wheels is calculated according to the following equation 2. The map corresponding to the graph shown in FIG. 6 is also obtained in advance experimentally, for example. ΔPf = ΔPfo (1 + ΔBEF / BEFo) (2)

At step 120, the target braking pressures Ptfl and Ptfr for the left and right front wheels are calculated as the sum of the master cylinder pressure Pm and the increased pressure ΔPf, and the braking pressures for the left and right front wheels are respectively set as the target braking pressures Ptfl and Ptfr. The front wheel system of the braking device 10 is controlled so that the target braking pressures Ptrl and Ptrr of the left and right rear wheels are set to the holding pressure Pc, and the braking pressures of the left and right rear wheels are respectively set to the target braking pressure Ptrl in step 130. And the rear wheel system of the braking device 10 is controlled so as to be Ptrr.

Although not shown in FIG. 3, if a negative determination is made in step 70 and if an affirmative determination is made in step 90, the communication control valve 22F or the like is operated. It is set to the standard position shown in FIG. 1, whereby the pressure Pm of the master cylinder 14 is directly supplied to the wheel cylinders 26FR to 26RR of each wheel, whereby the braking pressure of each wheel becomes the braking operation amount of the driver. It will be increased or decreased accordingly.

Thus, according to the illustrated embodiment, when the braking force distribution control for the front and rear wheels is not being executed, a negative determination is made in step 20, and in step 30, the basic of the rear wheels is determined based on the vehicle speed V. The holding pressure Pcs is calculated,
In step 40, the correction pressure ΔPc for the basic holding pressure Pcs is calculated based on the vehicle deceleration Gxb, and in step 50 the rear wheel holding pressure Pc is calculated as the basic holding pressure Pcs.
And the correction pressure ΔPc.

When the master cylinder pressure Pm is equal to or lower than the holding pressure Pc of the rear wheels and the other starting conditions for the braking force distribution control of the front and rear wheels are not satisfied, it is not necessary to suppress the braking force of the rear wheels. A negative determination is made in 60 and 70, and the front and rear wheel cylinders 26FL-26 are
The pressure in the master cylinder 14 is supplied to RR, so that the control for suppressing the braking pressure of the rear wheels and the control for increasing the braking pressure of the front wheels are not performed.

On the other hand, the braking operation amount by the driver is further increased, and the master cylinder pressure Pm becomes equal to the rear wheel holding pressure Pc.
If it exceeds, a positive determination is made in step 60, and the master cylinder pressure Pm is equal to the rear wheel holding pressure Pc.
If other starting conditions for the braking force distribution control for the front and rear wheels are satisfied even if the braking force distribution is not exceeded, a positive determination is made in step 70, and the holding pressure Pc of the rear wheels at that time is determined in step 80. The master cylinder pressure Pm is set, and in step 100, the basic increase pressure ΔPfo of the braking pressure of the front wheels is calculated according to the above equation 1 based on the deviation Pm-Pc between the master cylinder pressure Pm and the holding pressure Pc of the rear wheels. At 110, the braking effectiveness coefficient BEFv corresponding to the current vehicle speed is calculated based on the vehicle speed V, and the deviation ΔBEF between the standard braking effectiveness coefficient BEFo and the current braking effectiveness coefficient BEFv is calculated. The pressure increase pressure ΔPf is calculated.

Further, in step 120, the front wheel system of the braking device 10 is controlled so that the braking pressures of the left and right front wheels become the target braking pressures Ptfl and Ptfr calculated as the sum of the master cylinder pressure Pm and the increased pressure ΔPf. At 130, the rear wheel system of the braking device 10 is controlled so that the braking pressures of the left and right rear wheels become the target braking pressures Ptrl and Ptrr of the left and right rear wheels = holding pressure Pc.

Therefore, according to the illustrated embodiment, when the condition for starting the front / rear wheel braking force distribution control is satisfied, the master cylinder pressure Pm is kept at the rear wheel holding pressure Pc until the condition for ending the front / rear wheel braking force distribution control is satisfied. If the braking pressure exceeds the holding pressure Pc, it is possible to reliably prevent the rear wheel from locking before the front wheel, and the braking pressure on the rear wheel is exceeded. Is maintained at the holding pressure Pc, the increase amount ΔPf of the braking pressure of the front wheels corresponding to the shortage of the braking force is calculated, and the braking pressure of the front wheels is increased by ΔPf, so that the braking pressure of the rear wheels is maintained. The shortage of the braking force of the entire vehicle due to this is compensated for by increasing the braking force of the front wheels, so that the braking force of the entire vehicle can be reliably applied to the braking operation amount of the driver even while the front and rear wheel braking force distribution control is being executed. By controlling to the corresponding braking force Wear.

FIG. 7 shows the relationship between the braking force Fbf of the front wheels and the braking force Fbr of the rear wheels in the illustrated embodiment,
Particularly, the chain double-dashed line shows the ideal front-rear distribution line, and the solid line shows the front-rear distribution line in the embodiment. As shown, the braking force Fbf of the front wheels corresponds to the holding pressure Pc of the rear wheels Fbfc.
In the following range, the braking force Fbf of the front wheels and the braking force Fbr of the rear wheels increase at a constant rate with respect to each other as the master cylinder pressure Pm increases, but the braking force F of the front wheels is
In the range where bf exceeds the braking force Fbfc corresponding to the holding pressure Pc of the rear wheels, the braking force Fbr of the rear wheels is set so that the actual front-rear distribution line of the braking force does not exceed the ideal front-rear distribution line.
The braking force Fbrc corresponding to c is maintained.

The solid line in FIG. 8 shows the relationship between the master cylinder pressure Pm and the front wheel braking pressure Pf and the rear wheel braking pressure Pr in the illustrated embodiment, and the two-dot chain line represents the front and rear wheel control. The relationship between the master cylinder pressure Pm, the front wheel braking pressure Pf, and the rear wheel braking pressure Pr when the power distribution control is not performed is shown.

As shown in FIG. 8, when the master cylinder pressure Pm is below the holding pressure Pc, the braking pressure Pf of the front wheels and the braking pressure Pr of the rear wheels are the master cylinder pressure Pm and are the same. However, if the master cylinder pressure Pm exceeds the holding pressure Pc, the braking pressure Pr of the rear wheels is the holding pressure Pc (constant), and if the current master cylinder pressure Pm is Pma, the braking of the rear wheels is performed. Pressure suppression amount ΔPr
An increase amount ΔPf of the braking pressure of the front wheels corresponding to the amount of suppression of the braking force of the rear wheels corresponding to (= Pma−Pc) is calculated, and the braking pressure Pf of the front wheels is controlled to Pma + ΔPf.

Particularly, according to the illustrated embodiment, the increase amount ΔPf of the braking pressure of the front wheels is not simply set to the suppression amount ΔPr of the braking pressure of the rear wheels, but the braking pressure of the rear wheels is suppressed. Is calculated as a value for adding the braking force corresponding to the shortage of the braking force to the braking force of the front wheels, the braking pressure of the front wheels is the master cylinder pressure Pma + the amount of suppression ΔPr of the braking pressure of the rear wheels.
As compared with the case where the setting is made, it is possible to control the braking force of the entire vehicle to a value that corresponds to the braking operation amount of the driver more reliably and accurately.

Generally, as the vehicle speed V becomes higher, the braking effectiveness of the front wheels becomes lower than that of the rear wheels, and as a result, the front-rear distribution of the braking force becomes closer to the rear wheels. The holding pressure Pc is preferably set low. Generally, the higher the vehicle load is, the closer the ideal front-rear distribution line of the braking force is to the rear wheels, and the higher the vehicle load is, the lower the deceleration of the vehicle is and the more the load on the front wheels for braking the vehicle increases. It is preferable that the lower the vehicle deceleration at the start of the braking force front / rear distribution control, the higher the rear wheel holding pressure Pc is set.

According to the illustrated embodiment, the holding pressure Pc is not set to a constant value, but steps 50 to 70 are performed.
The higher the vehicle speed V, the smaller the vehicle deceleration Gxb
Vehicle speed V and deceleration Gxb
Since the holding pressure Pc of the rear wheel is variably set in accordance with the above, the holding pressure Pc of the rear wheel can be set appropriately as compared with the case where the vehicle speed V and the deceleration Gxb of the vehicle are not taken into consideration. The front / rear wheel braking force distribution control can be appropriately executed according to the situation of.

Also according to the illustrated embodiment, step 1
In 10, the increasing pressure ΔPf of the braking pressure of the front wheels is calculated in consideration of the fact that the braking effectiveness coefficient BEF decreases as the vehicle speed V increases, so that the front wheels are compared with the case where the fluctuation of the braking effectiveness coefficient BEF is not considered. Increased braking pressure ΔP
f can be calculated to a value that accurately corresponds to the shortage of the braking force of the rear wheels, and thus the braking pressure of the front wheels can be properly controlled without excess or deficiency.

Although the present invention has been described in detail above with respect to a specific embodiment, the present invention is not limited to the above-described embodiment, and various other embodiments within the scope of the present invention. It will be apparent to those skilled in the art that

For example, in the illustrated embodiment, the rear wheel holding pressure Pc is set to a constant value until the condition for ending the front / rear wheel distribution control of the braking force is satisfied.
For example, the holding pressure P of the rear wheels is changed according to the slip state of the front and rear wheels.
The braking pressure of the rear wheels may be gradually decreased or gradually increased by increasing the pulse pressure by increasing or decreasing c.

In the above-described embodiment, the rear wheel holding pressure Pc is variably set according to the vehicle speed V and the vehicle deceleration Gxb in steps 50 and 60. The wheel holding pressure Pc may be modified so as to be variably set only in accordance with one of the vehicle speed V and the vehicle deceleration Gxb. Further, as shown as a modified example in FIG. 9, the rear wheel holding pressure Pc is set. Pc is the vehicle speed V and the vehicle deceleration Gxb
It may be set to a constant value instead of being variably set according to.

Further, in the above embodiment, the rear wheel holding pressure Pc is set to the vehicle speed V in steps 100 and 110.
However, the correction of the holding pressure Pc of the rear wheels based on the change in the braking effectiveness coefficient may be omitted.

In the above embodiment, the left and right front wheels and the left and right rear wheels are controlled to have the same pressure during the front and rear wheel distribution control of the braking force. The braking pressures of the left and right front wheels or the braking pressures of the left and right rear wheels may be adjusted to different values depending on the situation and the behavior of the vehicle.

Further, in the above embodiment, the left and right front wheels and the left and right rear wheels each have one system, and the braking pressure of each system is mainly controlled by the communication control valves 22F and 22R. The braking system to which the above braking control device is applied can control the braking pressure of the front wheels to a value higher than the master cylinder pressure and the braking pressure of the rear wheels to a value lower than the master cylinder pressure. As long as it is, it may have any constitution known in the art.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a hydraulic circuit and an electronic control device of one embodiment of a braking control device according to the present invention.

FIG. 2 is a schematic sectional view showing a communication control valve for the front wheels shown in FIG.

FIG. 3 is a flowchart showing a braking force distribution control routine for front and rear wheels in the illustrated embodiment.

FIG. 4 is a graph showing a relationship between a vehicle speed V and a rear wheel basic holding pressure Pcs.

FIG. 5 is a graph showing the relationship between the vehicle deceleration Gxb and the correction pressure ΔPc with respect to the basic holding pressure Pcs.

FIG. 6 is a graph showing a relationship between a vehicle speed V and a braking effectiveness coefficient BEF.

FIG. 7 is a graph showing an ideal front-rear distribution line and a relationship between a front wheel braking pressure Pf and a rear wheel braking pressure Pr in the illustrated embodiment.

FIG. 8 is a master cylinder pressure P in the illustrated embodiment.
It is a graph which shows the relationship between m, the braking pressure Pf of a front wheel, and the braking pressure Pr of a rear wheel.

FIG. 9 is a flowchart showing a braking force distribution control routine for front and rear wheels in a modification of the illustrated embodiment.

[Explanation of symbols]

10 ... Braking device 14 ... Master cylinder 22F, 22R ... Communication control valve 26FL, 26FR, 26RL, 26RR ... Wheel cylinders 42F, 42R ... Oil pump 28FL-28RR, 34FL-34RR ... Open / close valve 42F, 42R ... Pump 60F, 60R ... Intake control valve 70 ... Valve room 74 ... Valve element 84 ... Compression coil spring 88 ... Check valve 90 ... Electronic control unit 96 ... Pressure sensor 98 ... Vehicle speed sensor 100 ... longitudinal acceleration sensor

Claims (3)

[Claims] 1. A braking force is generated by supplying hydraulic fluid pressure of a master cylinder to a wheel cylinder of a braking force generation device provided corresponding to each wheel, and when the operating state of a vehicle reaches a predetermined state, the rearward movement is performed. A braking control device for a vehicle that performs front and rear wheel braking force distribution control that suppresses an increase in the braking force of the wheels. A braking control device for a vehicle, comprising front wheel braking force increasing means for increasing a braking force of a front wheel. 2. The front and rear wheel braking force distribution control is performed by suppressing an increase in the wheel cylinder pressure of the rear wheels, and the front wheel braking force increasing means controls the braking operation amount by the driver and the wheel cylinder pressure of the rear wheels. And a parameter representing the braking performance of the braking force generation device for the front wheels and the rear wheels, the wheel cylinder pressure increase amount of the front wheels is calculated, and the wheel cylinder pressure of the front wheels is increased based on the increase amount. Item 3. A vehicle braking control device according to item 1. 3. The braking control device for a vehicle according to claim 2, wherein the parameter is a parameter that represents a lower braking performance as the vehicle speed increases.