JPH0611268Y2 - Brake device - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a braking device for a vehicle, and in particular, the braking force from the brake booster to the master cylinder side is increased or decreased during braking,
The present invention relates to a brake device that can prevent a wheel that tends to lock from being locked.

[Conventional technology]

The brake device of the vehicle supplies the hydraulic pressure generated in the master cylinder based on the pedaling force to each braking cylinder via the hydraulic pipe, and operates so as to apply the braking force to the wheels. In particular,
With a master cylinder that is configured to apply the pedaling force from the brake pedal side via the brake booster, the pressing force of the power piston in the brake booster is added as an urging force to this pedaling force to obtain a larger braking hydraulic pressure. be able to.

By the way, a switching valve is installed in each passage that can communicate with a pair of air chambers of the brake booster directly connected to the master cylinder, and by switching these valves, the hydraulic pressure of the master cylinder is reduced when the wheels tend to lock. The device is known. For example, FIGS. 8 (a) and 8 (b)
As shown in, the wheel speed and the brake fluid pressure are controlled during braking. That is, when braking is started (t0), the tendency of the wheels to lock is detected, a threshold value R of a predetermined slip amount is calculated, and the hydraulic pressure extraction / retraction information is obtained from this threshold value and the wheel speed WV. Based on the same information, the hydraulic pressure release process N,
The hydraulic pressure filling process K is alternately performed. As a result, the locking tendency of the wheels is released and skid of the vehicle can be prevented.

[Problems to be solved by the device]

In the case of such a conventional device, the air pressures in the left and right air chambers (here, A and B chambers) of the brake booster are operated as shown in FIG.

Here, when the gas acting on both air chambers of the brake booster is alternately switched between the negative pressure and the atmosphere during the lock release control, that is, the anti-skid control during the brake operation, the housing of the brake booster is correspondingly changed. The power piston slides in the inside. By the way, as shown in FIG. 8 (b), the loosening angle α0 as a time-dependent characteristic when the brake fluid pressure is released (when the braking force is loosened) is determined by the force of the return spring and the air flow resistance of the air chamber. . If this loosening angle α0 is large, the hydraulic pressure will be released quickly, and the unlocking control will be performed. If it is small (α
It is considered that the lock tight control (shown as 1) is performed. Here, anti-skid control is preferable when the friction coefficient (μ) of the road surface is large when the friction coefficient (μ) is large, and when the friction coefficient (μ) is small, it is desirable to relate the road surface condition to the anti-skid control. It is desired to associate road surface conditions from the beginning of control.

It is an object of the present invention to provide a brake device capable of improving braking safety during wheel unlocking processing accompanying vehicle braking.

[Means for Solving the Problems]

In the braking device of the present invention, a brake pedal is attached to a master cylinder for braking through a brake booster, and a first chamber and a second chamber are provided in the brake booster with a power piston interposed therebetween. The power piston has a first chamber. In the brake device for applying the elastic force of the return spring and the pedaling force from the brake pedal so as to oppose each other, first flow path switching means for switching and communicating the first chamber from the sealed state to the negative pressure source and the atmosphere open path. A second flow path switching means for switching and communicating the second chamber from a sealed state to a negative pressure source and an atmosphere open path, and an adjustment attached to the atmosphere open path side of the first flow path switching means for variably adjusting the atmospheric flow rate. At least the first flow path switching to increase / decrease the master cylinder hydraulic pressure based on a valve and skid information obtained according to vehicle wheel speed information. It switches the stage, characterized in that a control means for controlling the operation of the control valve in accordance with the amount of raindrops information.

(Operation) Since the control means controls the operation of the adjustment valve that variably adjusts the air circulation amount on the atmosphere open road side of the first flow path switching means according to the raindrop amount information, the first brake booster
When air is introduced into the chamber to reduce the master cylinder hydraulic pressure, the pressure reduction gradient can be appropriately controlled according to the amount of raindrops, and the loosening process can be executed according to the road surface condition corresponding to the amount of raindrops.

〔Example〕

The brake device of FIG. 1 is for a vehicle, and supplies the hydraulic pressure of the master cylinder 3 to the front and rear hydraulic pipes 1 and 2. This brake device includes a brake booster 4 directly connected to a master cylinder 3 and first and second air chambers 7 and 8 divided by a power piston 6 in a housing 5 thereof.
A first pipe 20 extending from the first air chamber 7 and a passage 21 extending from the second air chamber 8, a first solenoid valve 9 on the first pipe 20, and a second pipe 22 on the second pipe 22 communicating with the passage 21. Two
The solenoid valve 40, a negative pressure tank 11 as a fluid pressure source for supplying a negative pressure to both valves 9 and 40, and a controller 12 as a control means for switching and controlling both valves.

The brake booster 4 is fixed to a vehicle dashboard 37, and its housing 5 is formed of a cast base and a sheet metal cylinder. The push rod 13 is slidably inserted into the central boss portion 16 of the housing 5 in the direction of its center line. One end of the push rod 13 is pin-connected to the brake pedal 14 via a connector 15, and the other end is in contact with the power piston 6. The power piston 6 is slidably fitted onto the boss portion 16, and boots extending from the outer peripheral edge of the power piston 6 secure the sealing performance between both air chambers. This power piston 6 has a piston rod 1
7 is attached integrally.

The tip of the piston rod 17 is in contact with a piston (not shown) in the master cylinder 3. A spring 19 for returning the power piston 6 is mounted between the inner wall surface of the housing 5 on the distal end side and the power piston 6. A first pipe 20 that communicates with the first air chamber 7 is extendedly formed on the front side portion of the tubular portion of the housing 5, and a first solenoid valve 9 as a first flow path switching means is connected to the end portion thereof. There is.

The first solenoid valve 9 is a solenoid in its casing,
Operates the valve body integrated with the movable iron core. That is, this solenoid valve 9
Is for opening the first air chamber 7 to the negative pressure tank 11 when it is off and for opening the first air chamber 7 to the atmosphere opening port 2 through the duty valve 39 when it is on.
Connect to 4 respectively.

The first electromagnetic valve 9 is provided with a duty valve 39 as an adjusting valve for variably adjusting the air circulation amount in the atmosphere open path. Here, the duty valve 39, the first solenoid valve 9, and the second solenoid valve 40 on the second pipe 22, which is similar to the same valve, are the controller 12
Controlled by.

Here, the duty valve 39 variably adjusts the air circulation amount according to the duty ratio of the output signal output from the controller,
That is, the amount of pressing is increased or decreased.

A raindrop amount sensor 38 is connected to the controller 12 in this case. The raindrop sensor 38 is attached to the front surface of the vehicle body facing upward, and outputs information on changes in the friction coefficient μ of the road surface due to rainfall. Here, the controller 12 is the raindrop amount sensor 3
A squeezing amount corresponding to the squeezing diameter corresponding to the characteristics shown in FIG. 7 is calculated according to the raindrop amount information of 8.

The squeezing amount corresponding to the squeezing diameter may be changed linearly as shown in FIG. 7, or may be set so as to be changed stepwise as shown by a broken line. First solenoid valve 9,
By the operation of the second solenoid valve 40, the operating pressure in each of the first and second air chambers operates as shown in FIG. Where the second
When the air chamber 8 is loosened, the pressure of the air chamber 8 is made negative by the action of the second solenoid valve 40.

The negative pressure tank 11 is connected to an intake passage of an engine (not shown), and is configured to supply negative pressure to the tank when the negative pressure in the tank becomes weaker than the intake passage side by the action of a one-way valve (not shown).

In addition to the raindrop amount sensor 38, the controller 12 includes wheel speed sensors 31 and 32 that output wheel speed signals of the rear left and right wheels,
A brake sensor 33 that outputs brake information and a G sensor 34 that outputs vehicle acceleration / deceleration information are connected.

A main part of the controller 12 is configured by a microcomputer, and a read-only memory (RO
An anti-skid control program is stored in M).

Here, the operation of this brake device will be described together with the program shown in FIG.

In the anti-skid control program, each sensor and power supply system are checked in the pre-processing, and if an abnormality is detected at this time, the following anti-skid control is canceled and the first solenoid valve 9 is turned off, that is, the negative solenoid valve 9 is turned off. Pressure in the first air chamber 7
Further, the negative pressure is continuously supplied to the second air chamber 8 via the second electromagnetic valve 40.

Next, at step a2, the brake signal is turned on, and steps a2 and a4 are repeated. In step a4, the no-brake state is maintained, that is, all the solenoid valves 9, 39, 40 are held off.

When the brake is turned on at time t1 (see FIGS. 3 (a) and 3 (b)), the second solenoid valve 40 is turned on, and then the process proceeds to step a5 to calculate the squeezing diameter information according to the raindrop amount information. Then, the duty valve 39 is driven and held by the output of the duty ratio according to the information. At this time, the braking force increases to T1 according to the pedaling force f2, as shown in FIG. Thereafter, it is detected whether or not the wheel speeds WV of the rear left and right wheels fall below the threshold value R1, that is, whether or not the vehicle is heading for skid (step a6). When it falls below the time point t2 (see FIGS. 3 (a) and 3 (b)), the routine proceeds to step a7, where the first solenoid valve 9 is switched on and the second solenoid valve 40 is switched off and held. Then, the process for releasing the brake hydraulic pressure, that is, the process for loosening the braking force is started. Here, the braking force is reduced from T1 to T2 (the pedaling force is a braking force corresponding to f2 only), and the brake fluid pressure is released. If the pedal effort is f1 or less, the braking force becomes zero. In the loop of steps a6 and a7, when the wheel speed WV recovers again within the set value R1 (time point t3), step a
Returning to step 2, the loop including the loading operation of steps a2, a3, a5 and a6 is repeated again.

After this, when the brake is released, all solenoid valves 9, 39, 4
The process returns to the process of turning off 0 (step a4).

During such anti-skid control, the brake oil pressure is increased or decreased, but during the brake force releasing process, that is, the brake force releasing process, the first air chamber 7 is brought to atmospheric pressure. Further, the flow of the atmosphere will be regulated by the squeezing amount of the duty valve 39. Here, when the weather changes during traveling and reaches a road surface where rain or snow falls, the duty ratio of the duty valve 39 is immediately changed to select a squeezing amount corresponding to a relatively large squeezing diameter.
The loosening angle α2 is largely controlled by unlocking,
Even on a snowy road that easily slips, stability during braking can be secured. If it is assumed that the pavement starts to run on a clear road from a snowy road, a duty ratio with a relatively small squeeze amount is selected, which results in a relatively small loosening angle α3 (Fig. 3 (b)). (See) will be loosened. In this case, anti-skid control for locking is performed, and it becomes easy to reduce the braking distance during braking.

In the above-mentioned place, the brake device has a rear wheel speed sensor.
Although it is attached only to the wheels, it may be attached to all the wheels and the anti-skid control may be entered when one of the wheels goes to the lock.

In the above-mentioned process, the second air chamber 8 communicates with the negative pressure tank 11 through the passage 21 and the second electromagnetic valve 40, but instead of this, the mechanical switching valve 10 is connected as shown in FIG. A configuration used in place of the second solenoid valve 40 may be adopted. As shown in FIG. 2, the switching valve 10 has a spool valve-shaped valve portion 101 at an intermediate portion of the push rod 13, an inner hole 102 into which the valve portion is fitted, and an opening 3 that opens in the inner hole.
It is formed by one opening 103, 104, 105.
The opening 103 is in the second air chamber 8, and 104 is the atmosphere open passage 38.
In addition, 105 communicates with the negative pressure tank 11, respectively.
The inner openings 103 and 104 are the maximum sliding amount L of the valve portion 101.
In order to correspond to 1, the required width is provided in the axial direction.

When the valve element 101 is located at the position shown by the solid line in FIG. 2 (during no braking), the openings 103 and 105 are connected by the communication opening 106 of the valve element, and when the push rod 13 slides to the left during braking, the opening occurs. It is possible to operate so that 103 and 104 are connected by the communication port 106.

In this case, the second solenoid valve 40 as shown in FIG. 1 is unnecessary, the switching control thereof is not required, and the control of the controller 12 can be simplified.

[Effect of device]

As described above, since the brake device controls the adjustment valve that variably adjusts the air circulation amount on the atmosphere release passage side communicating with the first chamber of the brake booster according to the raindrop amount information, when reducing the master cylinder hydraulic pressure. In addition, the decompression gradient can be controlled appropriately according to the amount of raindrops, loosening processing can be executed according to the road surface condition equivalent to the amount of raindrops, safety at the time of control can be secured, and in particular, appropriate control from the beginning of control can be responsive. Can do well.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a brake device as one embodiment of the present invention, FIG. 2 is a sectional view of a main part of a switching valve used in another embodiment of the present invention, and FIGS. 3 (a) and 3 (b). 1 is a diagram showing changes in wheel speed and brake fluid pressure over time during anti-skid control of the device shown in FIG. 1, FIG. 4 is a diagram for explaining a brake booster switching operation in the device shown in FIG. 1, and FIG. FIG. 6 is an explanatory view of the action of the brake booster and the pedal effort in the device, FIG. 6 is a flow chart of the anti-skid control program of the same device, and FIG. FIGS. 8 (a) and 8 (b) are diagrams showing changes in wheel speed and brake fluid pressure over time during anti-skid control of the conventional device, and FIG. 9 is an explanatory diagram of a brake booster switching operation in the conventional device. ing. 3 ... Master cylinder, 4 ... Brake booster, 5 ...
... Housing, 6 ... Power piston, 7, 8 ... Air chamber, 9 ... Electromagnetic valve, 10 ... Switching valve, 11 ... Negative pressure tank, 1 ... Controller, 14 ... Brake pedal, 24 ... Atmosphere release port, 31, 32 ... Wheel speed sensor, 33 ... Brake sensor, 34 ... G sensor, 38
...... Raindrop sensor, 39 ...... Duty valve, 40 ...... Second solenoid valve.

Claims (1)

[Scope of utility model registration request] 1. A brake master cylinder is equipped with a brake pedal via a brake booster, and a power piston is sandwiched in the brake booster to provide a first chamber and a second chamber. The power piston is returned to the first chamber. In a braking device that applies the elastic force of a spring and the pedaling force from the brake pedal so as to oppose each other, a first flow path switching means that switches and communicates the first chamber from a sealed state to a negative pressure source and an atmosphere opening path, Second flow path switching means for switching and communicating the second chamber from the sealed state to the negative pressure source and the atmosphere open path, and an adjusting valve mounted on the atmosphere open path side of the first flow path switching means for variably adjusting the atmospheric flow rate. , At least the first flow path switching means is switched to increase or decrease the master cylinder hydraulic pressure based on skid information obtained according to vehicle wheel speed information. In addition to the above, the brake device is provided with control means for controlling the operation of the adjusting valve according to the raindrop amount information.