JPH09109863A - Brake device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a device while the brake feeling is improved when the anti-skid is controlled by arranging a master cylinder provided with a small diameter piston to apply the medium to high brake pressure to a braking part of a wheel and a large diameter piston to apply the low pressure brake pressure. SOLUTION: A master cylinder 4 is provided with a pair of large diameter pistons 12 and two pairs of small diameter pistons 13, 14, and slidably arranged in a large diameter cylinder 15 and a small diameter cylinder 16 respectively. The brake fluid is fed from the large diameter piston 12 to wheel cylinders 7A7D in the low pressure range of the M/C brake pressure in which much brake fluid is consumed and in traveling on the low μ road. In the medium to high pressure in which the consumption of the brake fluid is small, the brake fluid is fed from the small diameter pistons 13, 14 to the wheel cylinders 17A-17D. A large volume of the brake fluid can be fed thereby, and generation of the M/C bottoming in a brake pedal 2 is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle brake device, and more particularly to a vehicle brake device having an anti-skid control function.

[0002]

2. Description of the Related Art Generally, in a vehicle brake device, a master cylinder and a braking portion (wheel cylinder) are connected through a pipe, and a brake pressure (hydraulic pressure) generated in the master cylinder by depressing a brake pedal is connected by the pipe. The wheel is braked by supplying it to the braking unit. Further, when the brake pedal is released, the hydraulic pressure of the braking unit is returned to the reservoir tank and the hydraulic pressure of the braking unit is reduced, so that the braking of the wheels is released.

On the other hand, a vehicle brake device having an anti-skid control function for preventing wheel lock during braking is
In the above vehicle brake device, a hydraulic pressure control valve is provided in a pipe path connecting the master cylinder and the braking unit, and the hydraulic pressure of the braking unit is controlled by switching the hydraulic pressure control valve according to the state of the wheel. It is said that. And
When the brake pressure becomes equal to or higher than a predetermined pressure, the hydraulic pressure control valve opens and closes to reduce the hydraulic pressure in the braking unit, thereby preventing the wheels from being locked.

As a vehicle brake device having the above-mentioned anti-skid control function, one disclosed in Japanese Patent Laid-Open No. 6-1225 is known. The vehicle brake device disclosed in the publication has two hydraulic circuits for driving a master cylinder and a braking portion. These two hydraulic circuits adopt the so-called diagonal split system, the first hydraulic circuit is connected to the braking parts of the right front wheel and the left rear wheel, and the second hydraulic circuit is the right rear wheel and the left front wheel. It is connected to the braking part of.

In addition to the above-mentioned hydraulic pressure control valve, a pump and a motor for driving the pump are respectively provided in the first and second hydraulic circuits. This pump and motor
It is arranged to return the brake fluid in the reservoir to the master cylinder during anti-skid control. In this way, by returning the brake pressure in the reservoir to the master cylinder during anti-skid control, it is possible to prevent so-called entry of the brake pedal during pressure reduction, and it is possible to maintain good brake feeling.

[0006]

However, in the conventional vehicle brake device having the anti-skid control function, it is necessary to dispose the pump and the motor in the first and second hydraulic circuits, respectively. These pumps and motors occupy a large portion of vehicle brake systems in terms of weight, size, and cost.

For this reason, in the conventional brake device for a vehicle having an anti-skid control function, the device becomes large in size,
There is a problem that the product cost increases as the weight increases. The present invention has been made in view of the above points, and has a configuration in which a small-diameter piston and a large-diameter piston are arranged in a master cylinder and the brake pressure generated in each piston is selectively supplied to a braking portion of a wheel. Accordingly, it is an object of the present invention to provide a vehicle brake device that is downsized, reduced in weight, and reduced in cost while maintaining good brake feeling during anti-skid control.

[0008]

The above-mentioned problems can be solved by taking the following means. Claim 1
In the described invention, in a vehicle brake device having an anti-skid control function for preventing wheel lock during braking, a small-diameter piston that applies a medium and high brake pressure to a braking portion provided on the wheel, and a low-pressure brake. A master cylinder having a large-diameter piston that exerts pressure on the braking portion, and a control means for controlling the brake pressure supplied from the master cylinder to the braking portion of each wheel are provided. is there.

According to a second aspect of the invention, in the vehicle brake device according to the first aspect, the first pipe for supplying the brake pressure of the small-diameter piston to each of the braking portions, and the first pipe. And a second pipe that supplies the brake pressure of the large-diameter piston to each of the braking units via the first pipe, and the brake pressure is reduced when the brake pressure of each braking unit is reduced. Third to return to the reservoir tank
And a throttle means provided in the second pipe for limiting the brake pressure supplied from the large-diameter piston to each of the braking parts to a predetermined pressure, and the first pipe,
A first on-off valve provided upstream of a position to which the second pipe is connected, a second on-off valve provided on the third pipe, and the first and second on-off valves. And a control means for controlling opening and closing.

According to a third aspect of the invention, in the vehicle brake device according to the second aspect, a third opening / closing valve is provided in place of the throttle means, and the first to third opening / closing valves are controlled by the control means. It is characterized in that the opening / closing control is performed by means.

According to a fourth aspect of the invention, in the vehicle brake device according to the second or third aspect, a brake pressure of a predetermined pressure or more is supplied to the braking portion to the second pipe. It is characterized in that a pressure reducing means for preventing the above is provided.

Each of the above means operates as follows. According to the invention of claim 1, since the master cylinder is configured to include the small diameter piston and the large diameter piston,
When a large-diameter piston is used, a large amount of brake fluid can be supplied to the braking portion with a small amount of brake pedal entry.

Therefore, in the low pressure region where the brake fluid consumption is high during the anti-skid control, the brake pressure generated by the large-diameter piston is set to be supplied to the braking portion by the control operation of the control means. The anti-skid control operation can be performed while preventing the occurrence of master cylinder bottoming due to the entry of the pedal.
That is, the anti-skid control operation can be performed only with the brake fluid supplied by the master cylinder.

As a result, the pump and motor that have been conventionally required for returning the brake fluid in the reservoir to the master cylinder are no longer required, and the vehicle brake device can be made compact and lightweight while maintaining good brake feeling. And cost reduction can be realized.

Further, in a region where the brake pressure is medium pressure and high pressure, the brake pressure generated by the small diameter piston is set to be supplied to the braking portion by the control operation of the control means, so that excessive brake fluid is supplied to the braking portion. It can be prevented from being supplied and the braking operation similar to the conventional one can be performed.

According to the second aspect of the present invention, the brake pressure of the small diameter piston is supplied to each braking portion via the first pipe, and the brake pressure of the large diameter piston is supplied to each braking portion via the second pipe. It Further, when the brake pressure is reduced, the brake fluid is returned from the braking unit to the reservoir tank via the third pipe. Further, the opening / closing operation of the first opening / closing valve is controlled by the control means to selectively supply the braking pressure of the small diameter piston and the braking pressure of the large diameter piston to the braking portion. Further, the opening / closing operation of the second opening / closing valve is controlled by the control means to control the amount of the brake fluid returned to the reservoir tank via the third pipe.

Further, the throttle means limits the brake pressure supplied from the large-diameter piston to each braking portion to a predetermined pressure. Therefore, in the pressure reducing mode of the anti-skid control operation, the brake pressure generated by the large-diameter piston can be prevented from returning to the reservoir tank via the third pipe, and the pressure reducing operation of each braking portion can be reliably performed.

Further, the required valve device is only the first and second on-off valves, the number of which is small, and the throttle means has a simple structure and is inexpensive as compared with the on-off valve. The configuration can be simplified and the cost can be reduced. Further, according to the invention of claim 3, a third opening / closing valve is provided in place of the throttle means provided in the configuration of claim 2, and the first to third opening / closing valves are opened / closed by the control means. With the control configuration, it is possible to completely prevent the brake pressure generated by the large-diameter piston from returning to the reservoir tank via the third pipe in the pressure reducing mode of the anti-skid control operation by the third opening / closing valve. As compared with the configuration according to claim 2, the pressure reducing operation of each braking portion in the pressure reducing mode can be reliably performed.

According to the invention of claim 4, the second aspect
By providing the pressure reducing means for preventing the brake pressure from being supplied to the braking portion above the predetermined pressure in the pipe, it is possible to reduce the change in the brake pressure with respect to the depression force of the brake pedal when the pressure is increased by the large diameter piston. Therefore, the controllability of the anti-skid control can be improved.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 shows a vehicle brake device 1 which is a first embodiment of the present invention. The vehicle brake device 1 according to the present embodiment is roughly divided into a master cylinder 4 connected to a brake pedal 2 via a brake booster 3, and a hydraulic pressure (brake pressure) generated in the master cylinder 4 to a right front wheel (FR), Left rear wheel (RL), left front wheel (F
L), first and second hydraulic circuits 5 and 6 for transmitting to wheel cylinders 7A to 7D (constituting a braking portion) respectively provided on the right rear wheel (RR), a reservoir tank 11 and the like. There is.

The brake booster 3 has a function of reducing the pedaling force applied by the driver on the brake pedal 2 by utilizing the vacuum pressure in the intake manifold, for example. The operating force of the brake pedal 2 is transmitted to the master cylinder 4 via the brake booster 3 to generate a brake pressure.

The master cylinder 4 has a large diameter (indicated by an arrow H in the figure).
1) and a pair of small-diameter pistons 13 and 14 having a small diameter (indicated by an arrow H2 in the drawing). The large-diameter cylinder 15 and the small-diameter cylinder 16 respectively. It is disposed so as to be liquid-tightly slidable therein. Also, the brake booster 3, the large-diameter piston 12,
The small-diameter pistons 13 and 14 are connected by connecting members 17 to 19. A brake fluid 20 and a spring 21 are arranged between the pair of large-diameter pistons 12, and a brake fluid 20 and springs 22 and 23 are similarly arranged between the small-diameter pistons 13 and 14, respectively. There is.

Therefore, when the brake pedal 2 is operated, the large-diameter piston 12 and the small-diameter pistons 13 and 14 provided inside the master cylinder 4 are displaced, and the brake fluid 20 arranged between the pistons is compressed. To generate brake pressure. At this time, since the large-diameter piston 12 has a large diameter, a large amount of the brake fluid 20 will be described later in the first and second hydraulic circuits even if the depression amount of the brake pedal 2 transmitted via the brake booster 3 is small. 5,6 can be supplied.

On the other hand, the small-diameter pistons 13 and 14 each having a small diameter size have a smaller amount of the brake fluid 20 than the large-diameter piston 12 even if the depression amount is the same. 6 cannot be supplied. still,
A reservoir tank 11 that stores the brake fluid 20 and supplies the brake fluid 20 to each of the pistons 12 to 14 is arranged above the master cylinder 4.

Next, the structure of the first and second hydraulic circuits 5 and 6 will be described. The vehicle brake device 1 according to the present embodiment has a so-called diagonal split type configuration, and the first hydraulic circuit 5 is provided to the wheel cylinders 7A and 7B for the right front wheel (FR) and the left rear wheel (RL). The second hydraulic circuit 6 is connected to the left front wheel (FL) and the right rear wheel (R).
(R) wheel cylinders 7C and 7D. Further, the first hydraulic circuit 5 and the second hydraulic circuit 6 have the same configuration, and further, for each wheel (FR, RL, FL, RR), the hydraulic circuits connected to the wheel cylinders 7A to 7D are connected. The configurations are substantially the same (specifically, there is only a difference in the arrangement of the proportional valves 33A and 33B on the front and rear wheels).

The first and second hydraulic circuits 5 and 6 are roughly the first pipes 25A to 25D and the second pipe 26A.
-26D, 3rd piping 27A-27D, the 1st on-off valve 3
0A to 30D, second opening / closing valves 31A to 31D, third opening / closing valves 32A to 32D, proportional valve 33B,
33D (hereinafter referred to as P valve) and the like.

As described above, the first hydraulic circuit 5 and the second hydraulic circuit 6 have the same structure, and the hydraulic circuits connected to the wheel cylinders 7A to 7D for each wheel have the same structure. Therefore, for convenience of description, in the following description, only the configuration and action and effect of the hydraulic circuit connected to the wheel cylinder 7A provided on the right front wheel (FR) will be described.
The description of the hydraulic circuits connected to the other wheel cylinders 7B to 7D is omitted.

The upstream end of the first pipe 25A is connected to the small-diameter piston 14 of the master cylinder 4 (in the second hydraulic circuit 6, it is connected to the other small-diameter piston 13). The generated brake pressure is supplied to the wheel cylinder 7A. In addition, the second pipe 26
A has its upstream end connected to the large-diameter piston 12 of the master cylinder 4, and supplies the brake pressure generated in the large-diameter piston 12 to the wheel cylinder 7A.

The downstream end of the second pipe 26A is connected to the first pipe 25A at a connecting portion 35A. Further, the connecting portion 35A of the second pipe 26A
A check valve 36A is provided on the upstream side, and is configured so that the brake fluid 20 does not flow backward from the wheel cylinder 7A to the large diameter piston 12.

The third pipe 27A is the first pipe 25.
B is a pipe that connects between the branch portion 37A provided at the downstream end of A and the reservoir tank 11, and the brake fluid 20 in the wheel cylinder 7A when the brake pressure is reduced, which will be described later.
Is provided for returning to the reservoir tank 11.
A connecting pipe 38A is arranged between the branch portion 37A and the wheel cylinder 7A.

On the other hand, the first to third on-off valves 30A to 32
Reference characters A are solenoid valves each of which opens and closes by an electric signal, and is connected to an anti-skid control device (not shown) (comprised of a microcomputer; hereinafter referred to as control device). This control device is configured to control the opening / closing of each of the on-off valves 30A to 32A as described later according to the skid state of the wheels.

The first on-off valve 30A is the first pipe 25A.
Is provided at an intermediate position and upstream of the connecting portion 35A to which the second pipe 25A is connected. Therefore, in the state where the first opening / closing valve 30A is open, the brake fluid 20 supplied from the small diameter cylinder 14 passes through the first opening / closing valve 30A and flows out to the connecting portion 35A. The generated brake pressure is the connecting portion 35A.
Is transmitted to Further, by closing the first opening / closing valve 30A, the supply of brake pressure from the small diameter cylinder 14 to the wheel cylinder 7A is cut off.

The second on-off valve 31A is connected to the third pipe 27A.
Is arranged at an intermediate position. As described above, since the third pipe 27A is a pipe provided to return the brake fluid 20 in the wheel cylinder 7A to the reservoir tank 11 when the brake pressure is reduced, the second opening / closing valve 31A is opened. As a result, the brake fluid 20 in the wheel cylinder 7A is
Flows out toward the reservoir tank 11 and the wheel cylinder 7A
The brake pressure inside is reduced. In addition, the second on-off valve 31A
Is closed, the outflow of the brake fluid 20 from the wheel cylinder 7A to the reservoir tank 11 is blocked.

The third on-off valve 32A has the above-mentioned connecting portion 35.
It is arranged between A and the branch portion 37A. The third opening / closing valve 32A is opened to open the large diameter cylinder 12
The brake fluid 20 supplied from the hydraulic fluid flows out to the wheel cylinder 7A, so that the brake pressure generated in the large diameter cylinder 12 is supplied to the wheel cylinder 7A. Further, by closing the third opening / closing valve 32A, the supply of the brake pressure from the large diameter cylinder 12 to the wheel cylinder 7A is cut off.

The P valves 33B and 33D are connected to the connecting pipes 38 connected to the wheel cylinders 7B and 7D of the rear wheels.
B and 38D are provided in order to bring the braking force distribution of the front and rear wheels closer to the ideal distribution and prevent the wheel lock of the rear wheels. Further, the check valve 42A provided in the pipe 41A that connects the connecting portion 39A provided in the first pipe 25A and the connecting portion 40A provided in the connecting pipe 38A is a brake pedal at the time of executing the anti-skid control described later. It is provided to recirculate the brake fluid 20 in the wheel cylinder 7A to the master cylinder 4 when the depression of 2 is released.

Next, the operation of the vehicle brake device 1 having the above structure will be described. First, prior to the description of the operation of the vehicle brake device 1, the consumption amount of the brake fluid 20 during the execution of the anti-skid control will be described with reference to FIG. FIG. 5 shows the brake pressure (M / C brake pressure) generated in the master cylinder 4 on the vertical axis, and the horizontal axis shows the amount of brake fluid 20 consumed on the left side and the pedaling force on the left side around the zero point. (Used amount) is shown.

Paying particular attention to the consumption amount of the brake fluid 20, the amount of the brake fluid 20 consumed in the low M / C brake pressure region (a region of about 0 to 11 kg / cm ² on the scale of the vertical axis). Are very many. It is also conceivable that the amount of brake fluid 20 consumed will also increase during traveling on a low μ road where antiskid control operations are frequently performed. On the other hand, when the M / C brake pressure is medium pressure or high pressure, the consumption amount of the brake fluid 20 is smaller than that in the low pressure region.

Therefore, the consumption amount of the brake fluid 20 is large M
When the / C brake pressure is in the low pressure region and when traveling on a low μ road, the so-called intrusion occurs in the brake pedal 2 during anti-skid control operation, and bottoming occurs (hereinafter, this bottoming is referred to as M / C bottoming). Can be considered.

However, in the vehicle brake device 1 according to this embodiment, the master cylinder 4 is provided with the large-diameter piston 12 and the small-diameter pistons 13 and 14, and the M / C brake pressure, which consumes a large amount of the brake fluid 20, is in the low pressure region. Also, when traveling on a low μ road, a large-diameter piston 1 capable of supplying a large amount of brake fluid 20 even if the amount of depression of the brake pedal 2 is small.
The brake fluid 20 is supplied from 2 to the wheel cylinders 7A to 7D so that the brake fluid 20 is supplied from the small diameter pistons 13 and 14 to the wheel cylinders 7A to 7D when the consumption amount of the brake fluid 20 is small and the pressure is high. It is configured.

With the above structure, the brake fluid 2
Even if the M / C brake pressure, which consumes a large amount of 0, is in the low pressure region and the vehicle runs on a low μ road, a large amount of the brake fluid 20 is supplied from the large-diameter piston 12 so that M / C is applied to the brake pedal 2. It is possible to prevent C bottoming from occurring. Further, when the large-diameter piston 12 is used, a large amount of the brake fluid 20 can be supplied even if the amount of depression of the brake pedal 2 is small as described above. It is possible to prevent bottoming from occurring.

As is apparent from the above description, the vehicle brake device 1 according to the present embodiment can prevent the M / C bottoming from occurring in the brake pedal 2 without using the pump and the motor which are conventionally required. It can be prevented. That is,
The anti-skid control operation can be performed only with the brake fluid 20 supplied by the master cylinder 4.

As described above, since the pump and the motor for returning the brake fluid in the reservoir tank, which has been conventionally required, to the master cylinder are not required, the vehicle brake device 1 can be downsized, reduced in weight and reduced in cost. It is possible to realize the above-mentioned improvement and to prevent the occurrence of M / C bottoming, so that it is possible to maintain a good brake feeling.

Further, in a region where the M / C brake pressure is medium and high, the brake pressure generated by the small diameter pistons 13 and 14 is configured to be supplied to the wheel cylinders 7A to 7D. 20 can be prevented from being supplied to the wheel cylinders 7A to 7D, and a reliable braking operation can be performed.

As described above, in the vehicle brake system 1 according to this embodiment, the large-diameter piston 12 is used as the supply source of the brake pressure supplied to the wheel cylinders 7A to 7D according to the magnitude of the M / C brake pressure. Switching with the small diameter pistons 13 and 14. This switching process is performed by the control device in the first to third
Open / close valves 30A to 30D, 31A to 31D, 32A to 3
It is performed by controlling the opening and closing of 2D. The switching process of each on-off valve executed by the control device during the anti-skid control will be described below.

As is well known, the anti-skid control operation includes a pressure increasing mode for increasing the brake pressure of the wheel cylinders 7A to 7D, a holding mode for holding the brake pressure of the wheel cylinders 7A to 7D, and a brake of the wheel cylinders 7A to 7D. A pressure reduction mode for reducing the pressure. Further, the master cylinder 4 provided in the vehicle brake device 1 according to the present embodiment has a large diameter piston 2 and small diameter pistons 13 and 14.
Therefore, the pressure increasing mode is divided into two, and there are a large diameter pressure increasing mode in which the pressure is increased by the large diameter piston 2 and a small diameter pressure increasing mode in which the pressure is increased by the small diameter pistons 13 and 14. It becomes a mode composition. The following table collectively shows the switching state of each on-off valve performed by the control device in each of the above modes.

[0046]

[Table 1]

As shown in the above table, in the small diameter pressure increasing mode (during normal brake operation and M / C brake pressure medium / high pressure during anti-skid control operation), the first opening / closing valve 3
0A to 30D and the third opening / closing valves 32A to 32D are opened, and the second opening / closing valves 31A to 31D are closed. Therefore,
The brake fluid 20 pressurized by the small-diameter pistons 13 and 14 has the first pipes 25A to 25D and the first opening / closing valves 30A to 30.
D, connecting pipe 38 through the third on-off valves 32A to 32D
It flows into A-38D and the brake pressure of wheel cylinders 7A-7D increases.

At this time, since the second opening / closing valves 31A to 31D are closed, the brake fluid 20 pressurized by the small diameter pistons 13 and 14 does not flow into the third pipes 27A to 27D. The brake fluid 20 pressurized by the large-diameter piston 12 is also supplied to the connecting portions 35A-35D via the second pipes 26A-26D, but the brake pressure generated by the large-diameter piston 12 is small. Since it is small with respect to the brake pressure generated by 14, most of the brake fluid 20 supplied to the wheel cylinders 7A to 7D is
The brake fluid 20 is pressurized by the small diameter pistons 13 and 14.

Further, in the large diameter pressure increasing mode (when the anti-skid control is operating and the M / C brake pressure is low), the first on-off valves 30A to 30D and the second on-off valves 31A to 31D are used.
Is closed, and the third on-off valves 32A to 32D are opened. Therefore, the brake fluid 20 pressurized by the large-diameter piston 12 is supplied to the second pipes 26A to 26D and the third opening / closing valves 32A to 32.
It flows into connection piping 38A-38D via D, and brake pressure of wheel cylinders 7A-7D increases.

At this time, since the first opening / closing valves 30A to 30D are closed, the brake fluid 20 pressurized by the large-diameter piston 12 does not flow into the first pipes 25A to 25D. Further, since the second on-off valves 31A to 31D are also closed, the brake fluid 20 pressurized by the large diameter piston 12
Flows into the third pipes 27A to 27D, and the reservoir tank 1
It is not returned to 1.

In the holding mode, the first to third on-off valves 30A to 30D, 31A to 31D, 32A to
All 32D are closed. Therefore, the wheel cylinder 7A
Even if a brake pressure of ~ 7D is applied to the branch portions 37A-37D by the connecting pipes 38A-38D, the second and third on-off valves 31A-31D, 32A arranged so as to sandwich the branch portions 37A-37D. Since ~ 32D is closed, the brake pressure of the wheel cylinders 7A-7D is maintained.

Further, in the pressure reducing mode, the first and third opening / closing valves 30A to 30D and 32A to 32D are closed, and the second opening / closing valves 31A to 31D are opened.
Therefore, the brake fluid 20 in the wheel cylinders 7A to 7D is
Are connection pipes 38A to 38D and second on-off valves 31A to 3D.
The brake pressure in the wheel cylinders 7A to 7D is reduced by being supplied to the reservoir tank 11 via 1D and the third pipes 27A to 27D.

As described above, the vehicle brake device 1 according to the present embodiment has the large diameter and small diameter pistons 12 to 14.
It is possible to realize the pressure increasing mode (small diameter pressure increasing mode, large diameter pressure increasing mode), holding mode, and pressure reducing mode even with the configuration using the master cylinder 4 having the above, and thus to surely execute the anti-skid control operation. You can

Next, a second embodiment of the present invention will be described. FIG. 2 shows a vehicle brake device 50 that is a second embodiment of the present invention. In FIG. 2, the same components as those of the vehicle brake device 1 according to the first embodiment shown in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

The vehicle brake device 50 according to this embodiment.
Removes the third on-off valves 32A to 32D provided in the vehicle brake system 1 according to the first embodiment, and
Instead of the third on-off valves 32A to 32D, the throttles 51A to
The feature is that 51D is provided.

The throttles 51A to 51D are the second pipe 26A.
26D are arranged upstream of the branch portions 37A to 37D and downstream of the check valves 42A to 42D. This diaphragm 51
A to 51D have a function of adjusting the pressure of the brake fluid 20 pressurized by the large-diameter piston 12 supplied via the second pipes 26A to 26D. Specifically, when the pressure applied by the large-diameter piston 12 exceeds a predetermined pressure,
Pressure adjustment processing is performed so that the pressure on the downstream side of the throttles 51A to 51D becomes the above-mentioned predetermined pressure.

Next, the operation of the vehicle brake device 50 according to this embodiment during the anti-skid control will be described. Also in the present embodiment, the controller performs the switching process of each on-off valve in setting the pressure increasing mode (small diameter pressure increasing mode, large diameter pressure increasing mode), the holding mode, and the pressure reducing mode executed during the anti-skid control. It is carried out by The following table collectively shows the switching state of each on-off valve performed by the control device in each of the above modes.

[0058]

[Table 2]

As shown in the above table, in the small diameter pressure increasing mode, the first opening / closing valves 30A to 30D are opened and the second opening / closing valves 31A to 31D are closed. Therefore, the brake fluid 20 pressurized by the small-diameter pistons 13 and 14 cannot be supplied to the first pipe 2
5A to 25D and the first opening / closing valves 30A to 30D, flow into the connecting pipes 38A to 38D, and the wheel cylinders 7A to
The 7D brake pressure increases. At this time, the second on-off valve 3
Since 1A to 31D are closed, the small diameter piston 13,
The brake fluid 20 pressurized by 14 is the third pipe 27A-
It does not flow into 27D.

Further, in the large diameter pressure increasing mode, both the first on-off valves 30A to 30D and the second on-off valves 31A to 31D are closed. Therefore, the brake fluid 20 pressurized by the large-diameter piston 12 is supplied to the second pipes 26A to 26D and the throttle 51.
Flows into the connection pipes 38A to 38D via A to 51D,
The brake pressure of the wheel cylinders 7A to 7D is increased.

At this time, since the first on-off valves 30A to 30D are closed, the brake fluid 20 pressurized by the large-diameter piston 12 does not flow into the first pipes 25A to 25D. Further, since the second on-off valves 31A to 31D are also closed, the brake fluid 20 pressurized by the large diameter piston 12
Flows into the third pipes 27A to 27D, and the reservoir tank 1
It is not returned to 1.

Also in the holding mode, as in the large diameter pressure increasing mode, the first opening / closing valves 30A to 30D and the second opening / closing valves 31A to 31D are both closed. Therefore, the brake pressure of the wheel cylinders 7A to 7D is equal to the connection pipes 38A to 38D.
Even if it is applied to the branch portions 37A to 37D by D,
The second and third on-off valves 31A to 31D and 32A to 32D arranged with the branch portions 37A to 37D sandwiched therebetween are closed, and the large-diameter piston 1 is attached to the second pipes 26A to 26D.
Since the check valves 36A to 36D are provided to prevent the brake fluid 20 from flowing toward the valve 2, the brake pressure of the wheel cylinders 7A to 7D is maintained.

Further, in the pressure reducing mode, the first on-off valves 30A to 30D are closed and the second on-off valve 3 is opened.
1A to 31D are opened. Therefore, the wheel cylinder 7
The brake fluid 20 in A to 7D is connected to the connecting pipes 38A to 38.
D, second on-off valves 31A to 31D, third pipe 27A to
The brake pressure in the wheel cylinders 7A to 7D is reduced by being supplied to the reservoir tank 11 via 27D.

At this time, since the second pipes 26A to 26D are connected to the branch portions 37A to 37D, the pressure of the brake fluid 20 pressurized by the large-diameter piston 12 is the branch portion 37A.
A to 37D. Therefore, suppose the large-diameter piston 1
The brake pressure generated in 2 is applied to the wheel cylinders 7A to 7D.
If it is higher than the brake pressure inside, the large diameter piston 12
The brake fluid 20 therein flows mainly into the reservoir tank 11 through the third pipes 27A to 27D, and the brake pressure in the wheel cylinders 7A to 7D is not efficiently reduced.

However, in the vehicle brake device 50 according to this embodiment, the branch portion 37 of the second pipes 26A to 26D is used.
Apertures 51A-5 having a pressure adjusting function on the upstream side of A-37D
1D is arranged. The throttles 51A to 51D are the second pipes 26 on the downstream side of the position where they are arranged.
The pressure adjustment processing is performed so that the pressure in A to 26B becomes smaller than the pressure of the brake fluid 20 that flows back from the wheel cylinders 7A to 7D to the reservoir tank 11 in the pressure reduction mode.

Therefore, in the depressurization mode, the brake fluid 20 in the large-diameter piston 12 does not flow into the third pipes 27A to 27D, and therefore the wheel cylinders 7A to 7D.
The internal brake pressure can be efficiently reduced. As described above, the vehicle brake device 5 according to the present embodiment.
Even at 0, the pressure increasing mode (small diameter pressure increasing mode, large diameter pressure increasing mode), the holding mode, and the pressure reducing mode can be surely realized. Further, the vehicle brake device 50 according to the present embodiment can remove the four on-off valves 32A to 32D from the vehicle brake device 1 according to the first embodiment described above. Further, the throttles 51A to 51D are open / close valves 32A.
It is a cheaper component than ~ 32D.

Therefore, the vehicle brake device 50 according to this embodiment can reduce the product cost as compared with the vehicle brake device 1 according to the first embodiment. Further, also in the control device configured by the microcomputer, the number of on-off valves to be controlled can be reduced to simplify the program, and the number of wires connecting the control device and the on-off valve can be reduced. You can

Next, a third embodiment of the present invention will be described. FIG. 3 shows a vehicle brake device 60 that is a third embodiment of the present invention. In FIG. 3, the same components as those of the vehicle brake device 50 according to the second embodiment shown in FIG. 2 are designated by the same reference numerals and the description thereof will be omitted.

The vehicle brake device 60 according to the present embodiment.
In the vehicle brake device 50 according to the second embodiment, the pressure reducing valve 61 that functions as a pressure reducing means that prevents the brake pressures higher than a predetermined pressure from being supplied to the wheel cylinders 7A to 7D is provided. It is a feature.

This pressure reducing valve 61 is used for the second pipes 26A to 26A.
It is located at D. Specifically, the second pipe 26A to
26D is connected to the large-diameter piston 12 after forming a single pipe 26, and the pressure reducing valve 61 is arranged in this pipe 26. In this way, the large-diameter piston 12
By providing the pressure reducing valve 61 on the downstream side, it is possible to keep the pressure in the second pipes 26A to 26D constant.

Next, the function and effect of the provision of the pressure reducing valve 61 will be described with reference to FIG. For example, when the vehicle travels on ice, or alternately runs on a high μ road and a low μ road, the pedaling force of the brake pedal 2 and the frequency of operation increase, and the large-diameter piston 12 generates M. /
C Brake pressure fluctuates greatly. Further, as described above with reference to FIG. 5, the consumption amount of the brake fluid 20 varies depending on the M / C brake pressure. Therefore, when the M / C brake pressure fluctuates greatly, the consumption amount of the brake fluid 20 becomes unstable,
The anti-skid control operation may not be performed properly.

However, by disposing the pressure reducing valve 61 in the second pipes 26A to 26D as in this embodiment, the pedaling force of the brake pedal 2 and the frequency of operation are increased, and the large-diameter piston 12 generates M. Even if the A / C brake pressure fluctuates greatly, the M / C brake pressure is stabilized because it is reduced by the pressure reducing valve 61 above a predetermined pressure (as shown in FIG. 5, regardless of the pedal effort, the M / C brake pressure). Is constant).

As described above, by stabilizing the M / C brake pressure, the fluctuation of the consumption amount of the brake fluid 20 is also stabilized, and thus the master cylinder 4 having the large diameter and small diameter pistons 12 to 14 is used. Even with anti-skid control, the controllability can be improved.

As is clear from the above description, the means for reducing the brake pressure generated by the large-diameter piston 12 is not limited to the pressure reducing valve 61, but any other structure can be used as long as the pressure reducing process is performed. May be For example, the pressure reducing valve 6
It is also possible to use an inexpensive P valve instead of 1.
In this case, the controllability of the antiskid control can be improved at low cost.

Next, a fourth embodiment of the present invention will be described. FIG. 4 shows a vehicle brake device 70 according to a fourth embodiment of the present invention. Note that, also in FIG. 4, the same components as those of the vehicle brake device 50 according to the second embodiment shown in FIG.

The vehicle brake device 70 according to the present embodiment.
In the vehicle brake device 50 according to the second embodiment, the third pipes 27A and 27B are provided with the reservoir 71, the third pipes 27C and 27D are provided with the reservoir 72, and the third pipes 27A to 27D are further connected. Large diameter piston 26
A pipe 26 located downstream of the second pipe 2
6A to 26D).

With the above structure, the pistons 12 to 14 do not stroke beyond the capacity obtained by adding the respective capacities of the reservoirs 71 and 72 in the anti-skid control. Therefore, by setting the capacity of the reserves 71, 72 to an appropriate capacity such that bottoming does not occur in the brake pedal 2, no matter what mode of anti-skid control, the pedaling force on the brake pedal 2 is determined. Even if you can prevent the occurrence of bottoming,
The pedal feel can always be good.

[0078]

As described above, according to the present invention, the following effects can be realized. According to the invention described in claim 1, the pump and the motor, which have been conventionally required for returning the brake fluid in the reservoir to the master cylinder, are not required, and the vehicle brake device is miniaturized while maintaining a good brake feeling. It is possible to realize weight reduction and cost reduction.

According to the second aspect of the invention, the required valve device is only the first and second on-off valves, the number of which is small, and the throttle means has a simple structure with respect to the on-off valve. Since it is inexpensive, the structure of the vehicle brake device can be simplified and the cost can be reduced.

According to the third aspect of the invention, in the depressurizing mode of the anti-skid control operation, the brake pressure generated by the large-diameter piston is returned to the reservoir tank via the third pipe by the third opening / closing operation. This can be completely prevented by the valve, and the depressurizing operation of each braking portion in the depressurizing mode can be reliably performed as compared with the configuration according to the second aspect.

Further, according to the invention described in claim 4, when the pressure is increased by the large-diameter piston, the change of the brake pressure with respect to the pedaling force of the brake pedal can be reduced, so that the controllability of the anti-skid control can be improved. .

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a vehicle brake device that is a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a vehicle brake device that is a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a vehicle brake device that is a third embodiment of the present invention.

FIG. 4 is a configuration diagram of a vehicle brake device that is a fourth embodiment of the present invention.

FIG. 5 is a diagram showing a relationship among pedaling force, M / C brake pressure, and brake fluid consumption.

[Explanation of symbols]

 1, 50, 60, 70 Vehicle brake device 2 Brake pedal 3 Hydraulic booster 4 Master cylinder 5 First hydraulic circuit 6 Second hydraulic circuit 7A to 7D Wheel cylinder 11 Reservoir tank 12 Large piston 13, 14 Small piston 20 Brake fluid 25A to 25D First piping 26A to 26D Second piping 27A to 27D Third piping 30A to 30D First opening / closing valve 31A to 31D Second opening / closing valve 32A to 32D Third opening / closing valve 33B, 33D P valve 35A-35D Connection part 36A-36D Check valve 37A-37D Branch part 38A-38D Connection pipe 51A-51B Throttle 61 Pressure reducing valve 71,72 Reservoir

Claims (4)

[Claims] 1. A vehicle brake device having an anti-skid control function for preventing wheel lock during braking, a small-diameter piston for applying medium and high brake pressures to a braking portion provided on the wheel, and a low-pressure brake. A master cylinder having a large-diameter piston that exerts a pressure on the braking portion, and a control means for controlling the brake pressure supplied from the master cylinder to the braking portion of each wheel are provided. Brake device. 2. The vehicle brake device according to claim 1, wherein a first pipe that supplies the braking pressure of the small-diameter piston to each of the braking units and the first pipe is connected to the large-diameter pipe. A second pipe for supplying the brake pressure of the piston to each of the braking parts via the first pipe; and a third pipe for returning the brake pressure to the reservoir tank when the brake pressure of each of the braking parts is reduced. A throttle means provided in the second pipe for limiting the brake pressure supplied from the large-diameter piston to each of the braking parts to a predetermined pressure; and in the first pipe, the second pipe is A first opening / closing valve provided upstream of the connected position; a second opening / closing valve provided in the third pipe; and a control means for controlling opening / closing of the first and second opening / closing valves. A vehicle blur characterized by comprising: Key equipment. 3. The vehicle brake device according to claim 2, wherein a third opening / closing valve is provided in place of the throttle means, and opening / closing control of the first to third opening / closing valves is performed by the control means. A vehicle brake device characterized by the above. 4. The vehicle brake device according to claim 2, wherein the second pipe is provided with a pressure reducing means for preventing the brake pressure from being supplied to the braking portion at a predetermined pressure or more. Brake device for vehicles characterized by.