JP2000025602A - Braking force controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid an excessive reduction of working fluid pressure from each cylinder for braking, in exercising the pressure intensifying/reducing control like regenerative, coordinative control using the working fluid pressure from a booster, separately from the working fluid pressure from a master cylinder. SOLUTION: A pressure intensifying control valve 30 for 4-wheel general control, which supplies or cuts off the working fluid pressure from a booster 4, is installed in the upper stream side of a pressure control cylinder 16, which controls the original pressure to wheel cylinders 1FL to 1RR for four wheels in order to reduce the input-pressure of this pressure control cylinder 16 by using a pressure reducing valve 31. A reservoir 32 having a constant capacity is arranged in the downstream side of the valve 31, so that the working fluid pressure, which is reduced by the pressure reducing valve 31, is not excessively reduced by the resisting force of a return spring. The pressure reducing valve 31 is connected with a check valve 35 like a bypass, so that the working fluid within the reservoir 32 is returned to the booster 4 as the booster pressure decreases.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called parallel hybrid vehicle having an engine and a motor generator, an electric vehicle having only a motor generator as a prime mover, and the like. The present invention also relates to a braking force control device for controlling a working fluid pressure to a braking cylinder of each wheel.

[0002]

2. Description of the Related Art Such a braking force control device is described in, for example, "Toyota Prius New Car Manual" (October 1997).
Month). During braking of the hybrid vehicle, a motor generator, which is originally an electric motor, is used as a generator, that is, a regenerative operation is performed to obtain a part of the braking force at the time of the braking by the regenerative torque of the motor generator, and the regenerative torque is generated by the motor generator. The charged power is charged to the battery. At this time, the braking force control device performs so-called cooperative control of the working fluid pressure to the braking cylinder. The regenerative cooperative control means that the amount of depression of the brake pedal is detected by, for example, the master cylinder pressure, and the amount obtained by subtracting the braking force by the regenerative torque of the motor generator from the braking force corresponding to the master cylinder pressure is equal to the braking force of each wheel. The working fluid pressure is controlled so as to be exerted by the working cylinder. When the working fluid pressure is controlled in this way, the working fluid pressure from the master cylinder, that is, the master cylinder pressure, is controlled by a stroke so that fluctuations in the working fluid pressure are transmitted from the master cylinder and the feeling of stepping on the brake pedal does not become uncomfortable. It is absorbed by an accumulator called a simulator.

[0003]

By the way, in the above prior art, the regenerative cooperative control is performed by directly increasing / decreasing the working fluid pressure from the master cylinder. For this reason, if an abnormality occurs in the control device, an abnormality-time compensation (fail-safe) such as a return to a normal braking system, that is, a system in which the master cylinder pressure is directly supplied to the braking cylinder of each wheel, is provided. There is a problem that it is difficult.

Therefore, for example, when controlling the working fluid pressure to the braking cylinder in this way, the master cylinder is separated from each braking cylinder, and the working fluid pressure from an individual pressure source is used as the original pressure. It is conceivable to connect it to the braking cylinder of each wheel and control it. As the source pressure of the working fluid pressure to be controlled, for example, a pressure from a working fluid pressure booster called a booster is used, and the pressure is controlled to a predetermined pressure by pressure increasing and decreasing pressure control valves. In specific regenerative cooperative control, the total original pressure of the working fluid pressure to the brake cylinder of a predetermined wheel such as four wheels or drive wheels is controlled by pressure control valves for increasing and decreasing pressure. In other words, unlike the master cylinder, a pressure increasing control valve is interposed in a line for supplying a working fluid pressure (hereinafter, also referred to as a booster pressure) from a booster that increases in pressure with the depression of a brake pedal to a braking cylinder of each wheel. The booster pressure can be supplied or cut off, and a common pressure reducing control valve is connected to the brake cylinder of each wheel so that the working fluid pressure of the brake cylinder of a predetermined wheel can be reduced at the same time. According to such a braking force control device, it is possible to construct a control system of the working fluid pressure to the braking cylinder such as the regenerative cooperative control while leaving the normal braking system. As a result, reliable fail-safe can be achieved.

In such a braking force control device, it is most convenient to release the working fluid pressure from the brake cylinder of each wheel, which has been reduced in pressure by the pressure reducing control valve, to a tank or the like to the atmosphere.
However, if the working fluid pressure from the brake cylinder of each wheel whose pressure has been reduced is released to the atmosphere as it is, for example, the pressure reduction control valve may be operated more than necessary, or the pressure reduction control valve may be erroneously opened. This causes a problem that the working fluid pressure of the brake cylinder of each wheel is excessively reduced.

The present invention has been developed in view of these problems, and the working fluid pressure from an individual pressure source different from the master cylinder is switched and connected to the brake cylinder of each wheel to increase or decrease the pressure. During control, the working fluid pressure of the brake cylinder of each wheel is stored in the reservoir so that the working fluid pressure of the brake cylinder of each wheel is not excessively reduced. It is an object of the present invention to provide a braking force control device that can perform the control.

[0007]

In order to solve the above-mentioned problems, a braking force control apparatus according to claim 1 of the present invention comprises:
A braking force for controlling a working fluid pressure to a brake cylinder of each wheel by switching between a working fluid pressure from a master cylinder and a working fluid pressure from a pressure source different from that of the master cylinder by increasing a pressure by depressing a brake pedal. A pressure increasing control valve for supplying and shutting off a working fluid pressure from a pressure source different from the master cylinder to a brake cylinder of each wheel, and braking each wheel from a pressure source different from the master cylinder. Pressure-reducing control valve for reducing the pressure of the working fluid supplied to the brake cylinder, and connected downstream of the pressure-reducing control valve to store the reduced pressure of the working fluid from the brake cylinder and to control the working fluid of each brake cylinder. A fluid pressure absorbing device for limiting the pressure so as not to be reduced below a predetermined pressure.

According to a second aspect of the present invention, in the braking force control device according to the first aspect of the present invention, the pressure reducing control valve includes a check valve that allows only the return from the fluid pressure absorbing device. Are connected by bypass.

According to a third aspect of the present invention, in the braking force control device according to the first or second aspect, the individual pressure source is a working fluid pressure boost device. It is.

[0010]

According to the braking force control device according to the first aspect of the present invention, the operation from the brake cylinder reduced in pressure by the fluid pressure absorption device connected downstream of the pressure reduction control valve. Since the fluid pressure is stored and the working fluid pressure of each brake cylinder is limited so as not to be reduced below a predetermined pressure, the working fluid pressure of the brake cylinder of each wheel is reduced even when the pressure reducing control valve malfunctions. Never too much.

Further, according to the braking force control device of the present invention, since the check valve that allows only the recirculation from the fluid pressure absorbing device is connected to the pressure reducing control valve by bypass, for example, the brake If the working fluid pressure from the individual pressure source is reduced by releasing the foot from the pedal, the working fluid pressure stored in the fluid pressure absorbing device automatically passes through the check valve to the individual pressure source side. Refluxed.

Further, according to the braking force control device according to the third aspect of the present invention, it is necessary to provide a new working fluid pressure source by using the working fluid pressure boost device as a pressure source separate from the master cylinder. And the structure can be simplified.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the braking force control device according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a braking force control apparatus according to the present invention, a so-called F
It is an example applied to an F type parallel hybrid vehicle. An engine EG, which is one of the prime movers of the parallel hybrid vehicle, includes a clutch C such as an electromagnetic powder clutch.
L, the motor is connected to the continuously variable transmission CVT. In the middle of the connection, an AC motor generator MG constituted by, for example, a three-phase induction motor / generator is interposed as another prime mover. The output shaft of the continuously variable transmission CVT is connected to front left and right wheels W _FL and W _FR that are drive wheels. Therefore, the front left and right wheels W _FL , W _FR are the engine EG,
When the motor generator MG is regenerated, the regenerative torque, that is, the electric braking force is applied to the front left and right wheels W _FL and W _FR. The electric power regenerated by the MG is charged into a battery (not shown). Incidentally, the clutch CL stops the engine EG and stops the clutch CL when the torque of the engine EG is not required, for example, in addition to the role as a so-called traveling clutch.
To cut off the connection between the engine EG and the drive system.

The engine EG is configured to be controlled by an engine control unit 37. The engine control unit 37 is provided with an arithmetic processing unit such as a microcomputer (not shown). And this engine control unit 37
Then, predetermined arithmetic processing is performed using, for example, an intake air amount, a throttle opening degree, an oxygen amount in exhaust gas, a coolant temperature, a vehicle speed, an engine speed, and a phase signal of an engine speed as control inputs. It outputs an intake air amount control signal to a throttle actuator in the road, an air-fuel ratio control signal to each injector, an ignition timing control signal to a distributor, and the like. The engine control unit 37 drives the engine EG in response to a command signal for starting and stopping the engine from a motor generator control unit 38 described later.

The clutch CL and the motor generator MG are controlled by a motor generator control unit 38, and the continuously variable transmission CVT is controlled by a continuously variable transmission control unit 39. Each of the control units 38, 39 Is configured by interposing an arithmetic processing device such as a microcomputer (not shown). These control units 38 and 39, including the engine control unit 37 and the brake control unit 9 described later, are configured to perform arithmetic processing while communicating with each other.

Among these, the continuously variable transmission control unit 39 performs predetermined arithmetic processing using a selected range, accelerator opening, brake pedal depression amount, input rotation speed, output rotation speed, and the like as control inputs. It outputs a gear ratio control signal, a working fluid pressure control signal to a working fluid pressure control valve, and a line pressure control signal. That is, the target speed ratio set based on, for example, the vehicle speed, the input speed, the accelerator opening, etc., and the speed ratio calculated based on the input speed and the output speed of the continuously variable transmission CVT match. The target gear ratio is set, for example, based on a gear shift pattern control map set in advance.The gear ratio increases as the vehicle speed decreases, and the gear ratio increases as the accelerator opening increases. The gear ratio is controlled so that the gear ratio increases as the input rotational speed increases.

The motor generator control unit 38 controls the clutch CL by performing predetermined arithmetic processing using vehicle speed, accelerator opening, battery charge state, battery temperature, input rotation speed, and the like as control inputs. It outputs a clutch control signal and a motor generator control signal to an inverter that substantially drives motor generator MG, and the inverter controls the direction and magnitude of the current supplied to motor generator MG according to the control signal.

That is, for example, by referring to a preset traveling pattern control map or the like, if it is determined from the accelerator opening degree that the accelerator pedal is depressed, the current traveling state of the vehicle is driven only by the motor generator MG. It is determined whether it is a motor traveling region to be driven, or an engine traveling region that travels only with the engine EG, a normal traveling is performed only with the engine EG, and a hybrid traveling region that uses the motor generator MG during acceleration, and the like.
While performing the powering control of the motor generator MG and the on / off control of the clutch CL according to the determined traveling area,
A command signal is output to the engine control unit 37. When it is determined that the accelerator pedal is released, if the vehicle speed is zero, it is determined that the vehicle is stopped and the clutch CL is released. On the other hand, when the vehicle speed is not zero and the anti-lock brake control is not performed by the brake control unit 9 described later, the power generation amount corresponding to the vehicle speed and the shift position is calculated with reference to an energy recovery amount calculation map (not shown). Set,
In accordance with the amount of power generation, motor generator MG is operated as a generator so-called regenerative operation, and the power is recovered by a battery (not shown). Further, the calculated power generation amount is notified to the brake control unit 9 as regenerative braking torque. On the other hand, when the anti-lock brake control is being performed by the brake control unit 9, the regenerative operation of the motor generator MG is stopped based on the actual braking status information from the brake control unit 9.

On the other hand, each of the wheels W _{FL to} W _RR is provided with a wheel cylinder 1F as a brake cylinder as a fluid pressure braking means.
L to 1RR are mounted, and between the master cylinder 2 or the booster 4 in front of it and the wheel cylinders 1FL to 1RR, which increase the pressure when the brake pedal 3 is depressed, and the working fluid pressure to the wheel cylinders 1FL to 1RR. , A brake actuator unit 10 is provided. Although details of the brake actuator unit 10 will be described in detail later, the brake actuator unit 10 is controlled by a brake control unit 9 provided with an arithmetic processing device such as a microcomputer (not shown). The brake control unit 9 also performs control while communicating with the engine control unit 37, the motor generator control unit 38, and the continuously variable transmission control unit 39.

Next, FIG. 2 shows details of the brake actuator unit 10. The brake actuator unit 10 separates the working fluid pressure to all four wheels from the master cylinder and controls the pressure increase / decrease. The four-wheel general control actuator unit 5 avoids the locking tendency of each wheel and secures the braking distance and performs steering. An anti-lock brake control actuator unit 6 for achieving both effects and a front wheel control actuator unit 7 for controlling only the working fluid pressure to the front wheels mainly in the pressure reducing direction are provided.

The master cylinder 2 shown in the figure can output the same working fluid pressure according to the amount of depression of the brake pedal 3 to two systems, and is basically a front left wheel cylinder (hereinafter simply referred to as a front left wheel). 1FL and rear right wheel cylinder (rear right wheel cylinder) 1
RR is connected to one of the systems of the master cylinder 2 and is a front right wheel cylinder (front right wheel cylinder) 1F
R and a rear left wheel cylinder (rear left wheel cylinder) 1RL are connected to the other system of the master cylinder 2 to constitute a so-called X piping type. As is well known, the advantage of this X-pipe type is that even if an abnormality occurs in one of the piping systems, the remaining piping system causes the front and rear wheels, and the left and right sides of the vehicle, to be connected. The point is that the braking force can be balanced and vehicle stability can be ensured. Although a booster 4 is interposed between the brake pedal 3 and the master cylinder 2, details of the structure and the like will be described later.

Here, in order to facilitate understanding, the structure of each of the wheel cylinders 1FL to 1RR from the structure of the antilock brake control actuator unit 6 will be described. The structure of the pressure control valve in the antilock brake control actuator unit 6 is the same as that of a conventional recirculation type. For example, one system from the master cylinder 2 is branched into two and the other system is divided into two systems. The wheel cylinders 1FL to 1RR are connected to the respective branches via anti-lock brake control pressure increase control valves 51FL to 51RR. Each of the pressure increase control valves 51FL to 51RR is a normally-open two-position switching solenoid valve for compensation at the time of abnormality, so-called fail-safe. Each pressure increase control valve 51
FL-51RR, each wheel cylinder 1FL-1R
Check valves 52FL to 52RR that allow only the recirculation of the working fluid from R to the master cylinder 2 side are bypass-connected.

Downstream of the anti-lock brake control pressure increase control valves 51FL to 51RR, anti-lock brake control pressure reduction control valves 53FL to 53RR comprising a normally closed two-position switching solenoid valve are connected. The output side is a common reservoir 54P, 5 for each system.
4S and the pumps 55P, 55S are branched and connected to the damper 5S.
The discharge side of each pump 55P, 55S is connected to each system of the master cylinder 2 via 6P, 56S. Thus, the working fluid pressure of each wheel cylinder 1FL-1RR is reduced by the pressure reduction control valves 53FL-53RR and the pump 55
It is returned to each system of the master cylinder 2 via P, 55S, dampers 56P, 56S.

The actuator unit 6 for anti-lock brake control is normally controlled according to the anti-lock brake control arithmetic processing executed in the brake control unit 9 based on a wheel speed signal or the like from a wheel speed sensor during normal times. You. That is, the relationship between each wheel speed and the vehicle speed is monitored. For example, when the slip ratio becomes equal to or more than a predetermined value and each wheel is likely to be locked, the pressure increase control valves 51FL to 51RR are closed and the wheel cylinder of the wheel concerned is closed. When the working fluid pressure of 1FL to 1RR is maintained and the locking tendency of the wheel does not recover, the pressure reduction control valves 53FL to 53RR are opened while operating the pumps 55P and 55S to open the wheel cylinder 1F.
The working fluid pressure of L to 1RR is recirculated to the master cylinder 2 side to reduce the pressure, and when the wheel speed is restored, the pressure reducing control valves 53FL to 53RR are once closed to maintain the working fluid pressure of the wheel cylinders 1FL to 1RR. Thereafter, the pressure increase control valves 51FL to 51
When the RR is opened, the working fluid pressure of the wheel cylinders 1FL to 1RR is gradually increased, that is, the pressure is gradually increased. By repeating this series of operations, the braking distance can be secured and the slip rate with a high steering effect, that is, each wheel speed is reliably reduced in the vicinity of the target wheel speed, so that the braking distance and the steering effect are reduced. The vehicle speed is surely reduced while balancing. When the anti-lock brake control (decompression) is started for any one of the wheel cylinders 1FL to 1RR while the motor generator is performing the regenerative operation as described above, the other anti-lock brake control is performed. The operation of this actuator will be described in detail later.

In this embodiment, the front left and right wheel anti-lock brake control pressure increase control valves 51FL, 51FL are provided.
Each downstream side of FR and front left and right wheel cylinders 1FL, 1F
A front wheel control actuator unit 7 is interposed between R and R. This front wheel control actuator unit 7
Is a normally open two-position switching solenoid valve interposed between each downstream side of the front left and right wheel antilock brake control pressure increase control valves 51FL and 51FR and the front left and right wheel cylinders 1FL and 1FR. Wheel pressure reduction control switching valves 41FL, 41FR, and check valves 42FL, 42FR that are bypass-connected to these and allow only recirculation from the front left and right wheel cylinders 1FL, 1FR to the master cylinder 2 side, and are further bypass-connected thereto. A proportioning valve 43F capable of substantially reducing the working fluid pressure to the front left and right wheel cylinders 1FL and 1FR.
L, 43FR. Incidentally, when the output pressure of the proportioning valves 43FL, 43FR is relatively low, for example, with respect to the input pressure on the master cylinder 2 side, the output pressure gradually increases with a pressure increase gradient smaller than the pressure increase gradient of the input pressure. When the input pressure exceeds a predetermined value,
What increases the pressure with the same pressure increase gradient as the input pressure is applied.

This front wheel control actuator unit 7
Is controlled mainly in accordance with the front left and right wheel pressure reduction control calculation processing executed in the brake control unit 9. That is, when the motor generator is operated for regenerative operation, the front and left and right wheel pressure reduction control switching valves 41FL, 41
By closing the FR, the proportioning valve 43F
Front left and right wheel cylinders 1FL,
The working fluid pressure of 1FR is controlled to be lower than the supply pressure on the master cylinder 2 side. That is, the vehicle of this embodiment is of the FF type, and the engine and the motor generator are connected only to the front wheels. Therefore, since the regenerative torque by the motor generator is also applied only to the front wheels, the front left and right wheel cylinders 1F
It is necessary to reduce the working fluid pressure of L, 1FR. Conversely, if the regenerative torque from the motor generator is applied only to the front wheels, simply reducing the working fluid pressure of all four wheel cylinders will result in a greater braking force on the front wheels than on the rear wheels. Therefore, there arises a problem that, for example, the antilock brake control is started early.
Therefore, in this embodiment, the working fluid pressure of the front left and right wheel cylinders 1FL, 1FR is reduced by the proportioning valves 43FL, 43FR by the braking force due to the regenerative torque. However, the regenerative torque generated by the motor generator changes depending on, for example, the vehicle speed. In the present embodiment, for example, a relatively stable but small regenerative torque that can be generated at medium to high speeds can be reduced by the proportioning valve.

Next, the booster 4 and the working fluid pressure source to the booster 4 will be described before the four-wheel integrated control actuator unit 5. In a hybrid vehicle such as the present embodiment, the engine may be stopped, so the electric pump 11 is used as a source of working fluid pressure to the booster 4. The working fluid in the main reservoir 8 is sucked by the electric pump 11 and the check valve 1
2 and is discharged. The accumulator 13 is connected to the discharge side of the electric pump 11, and further connected to the input side of the booster 4. Pressure switches 14 and 15 are provided on the upstream side and the downstream side of the accumulator 13, respectively, and the electric pump 11 is operated regardless of which one is lower, so that the working fluid pressure in the accumulator 13 is reduced. That is, the supply fluid pressure to the booster 4 can be maintained at a predetermined value or more.

The basic structure of the booster 4 is the same as the existing one. That is, when the brake pedal 3 is not depressed as shown in FIG. 3 (the state where the brake pedal 3 is depressed), the input shaft 71 is retracted to the right in the drawing, and as a result, the steel ball 72 Since the spring 74 presses the valve seat 73 against the valve seat 73, the working fluid pressure from the accumulator 13 taken in from the outer periphery of the piston 75
5 cannot flow into the cylinder chamber 76 inside, and no force for pressing the piston 75 is generated. The cylinder chamber 76 is also communicated with the inside of the booster body 70.
Further, a rod 77 connected to the master cylinder 2 extends from the piston 75. Also, reference numerals 78, 78 in the figure
79 is a return spring for retracting the piston 75 and the rod 77 to the right in the figure when the brake pedal 3 is not depressed.

When the brake pedal 3 is depressed from this state, the input shaft 71 is moved to the left in the drawing against the elastic force of the spring 80 interposed between the brake pedal 3 and the valve Moves the steel ball 72 together with the holder 82 to the left in the drawing against the elastic force of the spring 74, whereby the steel ball 72 is separated from the valve seat 73. Then, the working fluid pressure from the accumulator 13 flows into the cylinder chamber 76 in the piston 75 through a port 81 formed in the input shaft 71 from a gap between the input shaft 71 and the valve seat 73, Since the piston 75 is pressed to the left along with the valve seat 73, the rod 77 is moved to the master cylinder 2 side, and the working fluid pressure in the master cylinder 2 is increased. Of course, after this, the piston 75 together with the valve seat 73 is also moved by the input shaft 71.
May be pressed to the left, but the piston pressing by the working fluid pressure is always performed first, so that a large propulsion force can be obtained even if the depression force of the brake pedal 3 is small. The working fluid pressure in 2 is doubled (boosted).

Next, when the brake pedal 3 is depressed with the brake pedal 3 depressed to a certain extent, the valve seat 73 is depressed by the elastic force of the spring 80.
And the input shaft 71 are separated from each other, and as a state, the input shaft 71 is retracted rightward in the drawing relative to the valve seat 73 (however, the input shaft 7
1 is in contact with the steel ball 72), whereby the steel ball 72 is pressed against the valve seat 73 again by the elastic force of the spring 74, so that the gap between the two is closed and the working fluid pressure in the cylinder chamber 76 is reduced. And an assisting force for maintaining the piston 75 and the rod 77 moved toward the master cylinder 2 is obtained by the sealing pressure.

On the other hand, the brake pedal 3
When the foot is released, the input shaft 7 becomes free.
1 is further retracted rightward in the figure by the spring 80, and the steel ball 72 is separated from the input shaft 71 while the steel ball 72 is in contact with the valve seat 73. Then, the working fluid pressure in the cylinder chamber 75 flows from the gap between the input shaft 71 and the valve seat 73 to the flow path 83 and the flow formed in the input shaft guide 84 formed from the tip of the input shaft 71. The water returns to the main reservoir 8 through the passages 85 and 86 and the flow passage 87 formed in the booster body 70.

As described above, in the booster 4 of the present embodiment, the working fluid pressure from the accumulator 13 flows into the cylinder chamber 76 and rises at all times from the start of the depression of the brake pedal 3. Therefore, in the present embodiment, the working fluid pressure in the cylinder chamber 76 is increased together with the depression of the brake pedal 3 and is taken out as a working fluid pressure from a fluid pressure source different from the working fluid pressure of the master cylinder 2. A passage 88 was formed in the valve body 70. The working fluid pressure taken out therefrom is taken into the below-mentioned four-wheel general control actuator unit 5 and used for braking force control during regeneration.

Next, the overall configuration of the four-wheel integrated control actuator unit 5 will be described. First, each system of the two working fluid pressures from the master cylinder 2,
Regeneration switching valves 21P and 21S, which are two-position switching pilot valves that use the working fluid pressure extracted from the booster 4 as a pilot pressure, are interposed. The regenerative switching valve 21P, 2 comprising this two-position switching pilot valve
The P port of 1S is connected to the output side of each system of the master cylinder 2, the A port is branched to the anti-lock brake control pressure increasing control valves 51FL to 51RR, and the B port is a stroke composed of a kind of accumulator. It is connected to simulators 22P and 22S. The regenerative switching valves 21P and 21S communicate with the P port and the A port in a normal state without pilot pressure and check valves 20P and 20S.
Allows only return from port B to port P and port A. In the switching state by the pilot pressure, the port A is shut off and the port P and the port B are communicated. By the way, the stroke simulators 22P, 2P
As the 2S return spring, a spring having a spring constant equivalent to the working fluid pressure reaction force generated in the booster 4 and the master cylinder 2 is used, and excess working fluid is returned to the main reservoir 8. Also, each regenerative switching valve 21
Pressure sensors 2 are provided on the upstream and downstream sides of P and 21S, respectively.
3P, 23S and pressure sensors 24P, 24S are provided.

On the other hand, the working fluid pressure extraction system of the booster 4 is connected to the regenerative switching valve 21 via a fail-safe valve 25 comprising a normally closed electromagnetic two-position switching valve.
The branch pressure is supplied as a pilot pressure of P and 21S. The fail-safe valve 25 has a booster 4
A check valve 26 that allows only return to the side and a bypass valve 27 that is a normally closed two-position switching pilot valve are connected in parallel by bypass, and the pilot pressure of the bypass valve 27 is the downstream pressure of the fail-safe valve 25. (Or the downstream pressure of the bypass valve 27 itself). Thus, when the fail-safe valve 25 is opened in principle, the downstream pressure, that is, the bypass valve 27
The pilot pressure of the bypass valve 27 increases.
When the fail-safe valve 25 is closed in a state where the working fluid pressure from the booster 4 is low, the downstream pressure, that is, the pilot pressure of the bypass valve 27 is reduced, so that the bypass valve 27 is also closed. .

An orifice 2 is provided between the fail-safe valve 25 and each of the regeneration switching valves 21P and 21S.
And the orifice 28 is provided with the regenerative switching valve 2
A check valve 29 that allows only inflow to 1P and 21S (the pilot pressure thereof) is bypass-connected. In the drawing, the orifice 28 and the check valve 29 are provided one by one on the branch upstream side, but one each, that is, each regenerative switching valve 21 is provided on the branch downstream side.
You may make it interpose for every P, 21S.

Downstream of the fail-safe valve 25 or downstream of the bypass valve 27, a four-wheel general control pressure increasing control valve 30 comprising a normally open two-position switching solenoid valve, and a normally closed two-position A four-wheel general control pressure reducing control valve 31 composed of a switching solenoid valve and a four-wheel general control reservoir 32 are connected in series. The input port of the pressure control cylinder 16 is connected between the pressure increasing control valve 30 for the four-wheel general control and the pressure reducing control valve 31 for the four-wheel general control. In addition, the pressure control cylinder 16 is provided to the pressure increasing control valve 30 for the four-wheel general control.
A check valve 33 that allows only the recirculation from the four-wheel integrated control reservoir 32 and a relief valve 34 that relieves the upstream working fluid pressure of the pressure-increasing control valve 30 at a predetermined pressure or more are bypass-connected in parallel. . Also,
A check valve 35 that allows only reflux from the four-wheel integrated control reservoir 32 is connected to the four-wheel integrated control decompression control valve 31 by bypass. Further, the four-wheel general control reservoir 32 is of a type that supports the piston by the resistance of the return spring, and can absorb the amount of reduction in the working fluid pressure from all the wheel cylinders 1FL to 1RR generated by a normal brake operation. Has capacity. Also,
If necessary, a pressure sensor 36 for detecting the input working fluid pressure of the pressure control cylinder 16 may be attached.

The pressure control cylinder 16 has the same shape, that is, the cylinder portions 18P and 18S containing the pistons 17P and 17S having at least the same pressure receiving area on the input side and the same pressure receiving area on the output side. And each cylinder part 18P, 18S
Are connected to respective systems from the master cylinder 2 on the downstream side of the regeneration switching valves 21P and 21S. Of course, the return springs 19P, 19S of the respective cylinder portions 18P, 18S also have the same specifications including the spring constant. That is, the two cylinder portions 18P, 18P,
From 18S, the same working fluid pressure can be output from the master cylinder 2 to each of the two systems. The so-called pressure receiving area ratio between the pressure receiving area on the input side and the pressure receiving area on the output side of each of the pistons 17P and 17S is equal to or equal to the ratio between the output pressure of the master cylinder 2 and the working fluid pressure taken out of the booster 4. They are almost the same.

The four-wheel general control actuator unit 5 mainly includes the brake control unit 9.
It is controlled in accordance with the four-wheel general control arithmetic processing executed in the vehicle. That is, when no abnormality is detected as the braking force control device, the fail-safe valve 25 is opened, and when the brake pedal 3 is depressed in a state where the anti-lock brake control is not performed, the fail-safe valve 25 is removed from the booster 4. Since the working fluid pressure is increased, the bypass valve 27 that uses the downstream pressure of the fail-safe valve 25 as the pilot pressure is also switched and opened. The pressure downstream of the fail-safe valve 25 is equal to the value of the check valve 2.
9, the regenerative switching valves 21P and 21S are also supplied as pilot pressure.
1P and 21S are in the switching state, and the downstream side thereof, that is, the wheel cylinders 1FL to 1RR are shut off, and each system of the master cylinder 2 is connected to the stroke simulator 2S.
2P, 22S. Therefore, master cylinder 2
The working fluid pressure of each system of the stroke simulator 22
The piston in P, 22S is actuated, but the return spring generates a reaction force equivalent to the reaction force in the master cylinder 2 and the booster 4.
I don't feel uncomfortable with stepping on

On the other hand, since the regenerative torque by the motor generator can be obtained from the vehicle speed and the gear ratio as described above, the braking force of the front left and right wheels is calculated, and the pressure sensor 23P on the master cylinder side is calculated. , 23S
The braking force when the working fluid pressure is supplied to each of the wheel cylinders 1FL to 1RR is calculated from the working fluid pressure detected in the step (1), and the braking force including the difference between the two and the wheel cylinder side pressure sensors 24P and 24S are calculated. The output pressure from the pressure control cylinder 16 is controlled so that the braking force corresponding to the detected working fluid pressure matches. Here, since the pressure control cylinder 16 can supply the same working fluid pressure to the two systems connected to the X pipe, in order to control them in the same manner, the pressure control cylinder 16 What is necessary is just to control the pressure increase / decrease of the input pressure to. At this time,
The ratio between the output pressure and the input pressure of the pressure control cylinder 16 is determined by the pistons 17P, 1 of the two cylinder portions 18P, 18S.
Since it is the inverse ratio of the pressure receiving area ratio of 7S, the required working fluid pressure, that is, the input pressure increase / decrease amount with respect to the output pressure increase / decrease amount is set. Then, the opening and closing of the four-wheel general control pressure increasing control valve 30 and the four-wheel general control pressure reducing valve 31 may be controlled according to the amount of increase or decrease of the input pressure. In addition,
The control of increasing or decreasing the input pressure to the pressure control cylinder 16 is performed, for example, by using a conventional PWM with a duty ratio.
(Pulse WidthModulation) control etc. can be applied.
A detailed description thereof will be omitted. The working fluid pressure from each of the wheel cylinders 1FL to 1RR that has been reduced in pressure by the four-wheel general control pressure reducing valve 31 is stored in the four-wheel general control reservoir 32. In the four-wheel general control reservoir 32, each wheel cylinder 1 only has a pressure that balances the drag of the return spring.
Since the working fluid pressure of FL to 1RR cannot be reduced, even if the four-wheel general control pressure reducing valve 31 is opened, the working fluid pressure of each of the wheel cylinders 1FL to 1RR becomes lower than the fluid pressure balanced with the drag of the return spring. There is no decompression.

For example, when the regenerative switching valve is driven by a solenoid, an electric structure for driving the solenoid is required, and the regenerative operation time by depressing the brake pedal 3 as described above becomes longer. ,
For example, there is a problem that the excitation time of the solenoid becomes longer and the amount of heat generation becomes larger or energy loss becomes larger. However, in the present embodiment, the brake pedal is required to drive the regenerative switching valves 21P and 21S. 3
Since the working fluid pressure in the booster 4 which is constantly generated during the stepping on is used as the pilot pressure, the structure can be simplified, and the excess heat generation and energy loss can be prevented.

When the brake pedal 3 is depressed during the regenerative operation, even if the brake fluid is removed from the booster 4 by slightly returning the brake pedal 3, the regenerative switching valve 21P , 2
Since the pilot pressure to 1S only decreases slowly through the orifice 28, the regeneration switching valve 21
It is possible to prevent the P and 21S from erroneously returning to the normal position, and to continue the regenerative cooperative control. On the other hand, when the brake pedal 3 is depressed, the working fluid pressure taken out of the booster 4 flows from the check valve 29 side as the pilot pressure of the regenerative switching valves 21P and 21 without passing through the orifice 28, so that necessary responsiveness is secured. can do.

When the foot is released from the brake pedal 3 in this state, the working fluid pressure taken out of the booster 4 is also reduced as described above.
The pilot pressure of the regenerative switching valves 21P, 2S is also reduced slowly through the orifice 28.
1S returns to the normal position, and the master cylinder 2 is connected to the wheel cylinders 1FL to 1RR again. Also,
The working fluid in the four-wheel integrated control reservoir 32 passes through the check valve 35 and together with the working fluid in the pressure control cylinder 16, the check valve 33 and the check valve 2.
Reflux to booster 4 through 6. Further, when an abnormality is detected in a state where the brake pedal 3 is not depressed, the fail-safe valve 25 is closed, and the bypass valve 27 is also maintained closed even if the brake pedal 3 is depressed next time. Therefore, the working fluid pressure in the booster 4 is not supplied to the downstream side, and the regeneration switching valves 21P, 21P
S is the master cylinder 2 and the wheel cylinders 1FL to 1R
A fail-safe function can be obtained by maintaining R in communication.

On the other hand, if an abnormality is detected while the brake pedal 3 is depressed, the fail-safe valve 25 is immediately closed as described above. However, at this time, even if the fail-safe valve 25 is closed, the pilot pressure of the regenerative switching valves 21P and 21S is sealed because the downstream pressure of the fail-safe valve 25, that is, the working fluid pressure of the check valve 26 on the booster 4 side is high. The regenerative switching valve 21P,
21S keeps the working fluid system from the master cylinder 2 shut off. However, at this time, the pilot pressure of the enclosed regenerative switching valves 21P and 21S, that is, the downstream pressure of the fail-safe valve 25 acts as the pilot pressure of the bypass valve 27, so that the bypass valve 27 is kept open. Therefore, as a similar fail-safe measure, the pressure increasing control valve 30 for the four-wheel control is used.
Is maintained in the open state, and the four-wheel control pressure reducing control valve 31 is maintained in the closed state. Therefore, the working fluid pressure taken out from the booster 4 is continuously supplied to the two systems through the pressure control cylinder 16. Until the foot is released from the pedal 3, the braking by the working fluid pressure can be maintained. Since the pressure receiving area ratio between the pistons 17P and 17S of the two cylinder portions 18P and 18S of the pressure control cylinder 16 is set to the ratio between the output pressure of the master cylinder 2 and the working fluid pressure taken out from the booster 4, The working fluid pressure from the pressure control cylinder 16 that is sometimes obtained is equivalent to that from the master cylinder 2, stabilizes the braking force, and does not cause any discomfort.

In addition, the piston 1 of the two cylinder portions 18P and 18S of the pressure control cylinder 16 may be used.
By setting the pressure receiving area ratio of 7P and 17S to the ratio between the output pressure of the master cylinder 2 and the working fluid pressure taken out from the booster 4, the working fluid pressure from the pressure control cylinder 16 becomes equal to that from the master cylinder 2. Therefore, the control mode downstream of the antilock brake control actuator unit can be shared with that for the working fluid pressure from the master cylinder 2 to facilitate control.

As described above, in the present embodiment, the four-wheel general control pressure increase control valve 30 and the four-wheel general control for increasing and reducing the working fluid pressure from the booster which is a pressure source separate from the master cylinder. A four-wheel general control reservoir 32 as a fluid pressure absorbing device is disposed further downstream of the control pressure-reducing control valve 31, and the reservoir 32 stores the depressurized working fluid pressure from each of the wheel cylinders 1 FL to 1 RR. At the same time, the working fluid pressure of each of the wheel cylinders 1FL to 1RR is prevented from being reduced to a predetermined fluid pressure or less by the reaction force of the return spring, for example, by operating the four-wheel general control pressure reducing control valve 31 more than necessary. Of the wheel cylinders 1F even when the pressure reducing control valve is accidentally opened.
The working fluid pressure of L to 1RR is not excessively reduced.

In the above embodiment, the case where the front wheel pressure reduction control actuator unit and the anti-lock brake actuator unit are provided is described, but these may be set as required.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a hybrid vehicle to which a braking force control device of the present invention is applied.

FIG. 2 is a hydraulic circuit diagram showing an example of a brake actuator unit of FIG.

FIG. 3 is an explanatory diagram of the booster of FIG. 2;

[Explanation of symbols]

1FL to 1RR are wheel cylinders (braking cylinders) 2 is a master cylinder 3 is a brake pedal 4 is a booster 5 is a four-wheel general control actuator unit 6 is an anti-lock brake control actuator unit 7 is a front wheel control actuator unit 8 is a main unit The reservoir 9 is a brake control unit 10 is a brake actuator unit 11 is an electric pump 16 is a pressure control cylinder 17P, 17S is a piston 18P, 18S is a cylinder part 21P, 21S is a regenerative switching valve 22P, 22S is a stroke simulator 25 is a fail-safe valve 27 Is a bypass valve 28 is an orifice 30 is a pressure increasing control valve for four-wheel general control 31 is a pressure reducing control valve for four-wheel general control 32 is a reservoir for four-wheel general control 33 is a check valve 3 Is a relief valve 35 is a check valve 37 is an engine control unit 38 is a motor generator control unit 39 is a continuously variable transmission control unit 41FL and 41FR are front and left and right wheel pressure reduction control switching valves 42FL and 42FR are check valves 43FL and 43FR are proportioning Valve EG is engine MG is motor generator CVT is continuously variable transmission

Claims (3)

[Claims] 1. A hydraulic fluid pressure from a master cylinder, and a hydraulic fluid pressure from a pressure source different from that of the master cylinder, which is raised by depressing a brake pedal, are switched.
A braking force control device for controlling a working fluid pressure to a braking cylinder of each wheel, wherein the pressure increasing control is configured to supply and shut off a working fluid pressure from a pressure source different from the master cylinder to a braking cylinder of each wheel. A valve, a pressure-reducing control valve for reducing the working fluid pressure supplied to the brake cylinder of each wheel from a pressure source different from the master cylinder, and a pressure-reduced braking cylinder connected downstream of the pressure-reducing control valve. And a fluid pressure absorbing device for storing the working fluid pressure from the brake cylinder and restricting the working fluid pressure of each braking cylinder so as not to be reduced below a predetermined pressure. 2. The braking force control device according to claim 1, wherein a check valve that allows only recirculation from the fluid pressure absorption device is bypass-connected to the pressure reduction control valve. 3. The braking force control device according to claim 1, wherein the individual pressure source is a working fluid pressure boost device.