JPS6283242A - Braking device for vehicle - Google Patents

Abstract

PURPOSE:To make pressure in a wheel cylinder at the time of car stoppage intensifiable, by opening a selector valve to be closed at the car stoppage for the specified time long if a necessary condition for pressure booting occurs during valve closing. CONSTITUTION:A selector valve 40 is installed in a feed pipe 20, while brake pipes 21 and 22 are interconnected with each other at the first position, and these brake pipes 21 and 22 are cut off at the second position. And, when a wheel speed is slower than the setting car speed and a brake pedal 1 is operated, it is judged as stoppage, so the selector valve 40 is switched to the second position, holding pressure in each of wheel cylinders 4 and 5. Afterward, when a car moves due to a shortage of braking force, generating a wheel speed signal, and the brake pedal 1 is stepped on, it judges that a necessary condition for pressure boosting occurs there, and the selector valve 40 is switched to the first position. And, it is held at the first position for the specified time long, and pressure in these wheel cylinders 4 and 5 is made raisable with the brake pedal 1 operated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vehicle brake system having a stoppage maintenance function that automatically maintains brake pressure when the vehicle is stopped and automatically releases it when the vehicle starts.

[Conventional technology]

In this type of device, in order to obtain a stop maintenance function, the mask cylinder and foil cylinder are cut off from the time the vehicle stops until the vehicle starts moving, so if the vehicle starts moving due to insufficient braking force while the vehicle is stopped, the brake pedal is pressed. Pressure inside the foil cylinder cannot be increased even if the pedal is pressed again. Therefore, a check valve must be provided to allow flow from the mask cylinder to the foil cylinder.

On the other hand, Japanese Patent Application Laid-Open No. 59-149851 discloses a device having a stoppage maintenance function and an anti-skid function, but this device also cannot increase the pressure while the vehicle is stopped. Therefore, it is possible to install the above-mentioned check valve, but the installation of the check valve causes the brake pedal to enter during anti-skid control, which is not desirable in terms of brake pedal operability and has a negative impact on anti-skid control performance. Give a ♂.

[Problem that the invention seeks to solve]

The present invention solves the problem of deterioration of brake pedal operability and anti-skid controllability caused by using the above-mentioned check valve. The purpose is to easily increase pressure with a simple configuration.

Measures to Solve Problems] Therefore, in the present invention, the following measures have been taken. That is, a pressure generating means that generates brake pressure when the brake pedal is depressed, a braking means that is actuated by the brake pressure to generate braking force, and a switching valve that closes when the vehicle is stopped to cut off communication between the two means. The switching valve described in 11a is a vehicle brake device that is opened for a predetermined period of time when a pressure increase requirement occurs while the switching valve is closed.

〔Example〕

The present invention will be explained below with reference to illustrated embodiments.

FIG. 1 shows an embodiment of the invention. This embodiment is an example in which the present invention is applied to a so-called FR vehicle, and for ease of understanding, only the piping system for the front two wheels is shown, and the configuration of the piping system for the rear two wheels is almost the same as that for the front two wheels. It is. Brake oil is supplied to the wheel cylinder 4 of the right front wheel and the wheel cylinder 5 of the left front wheel from the same pipe line. The brake pedal 1 is connected to a mask cylinder 3 via a vacuum booster 2, and the hydraulic pressure generated in the mask cylinder 3 (pressure generating means) when the brake pedal 1 is depressed passes through a pipe as described later. Each wheel cylinder for the right front wheel and left front wheel is 4°5 (braking means).
The signal is then transmitted to each wheel cylinder of the left and right rear wheels, and a braking action is performed.

As is conventionally known, the vacuum booster 2 is driven by negative pressure generated in the intake manifold of the engine, and is operated by energizing the pump 7 cylinder connected to the piston of the mask cylinder 3 in response to the depression of the brake pedal 1. Reduces the force required by the driver to press the brake pedal.

The mask cylinder 3 has two pressure chambers (not shown) that discharge brake oil of the same pressure, and each pressure chamber is connected to a supply pipe 20, 30, respectively. The supply pipe 20 branches into brake pipes 21, 22, the brake pipe 21 being connected to the wheel cylinder 4 of the right front wheel, and the brake pipe 22 being connected to the wheel cylinder 5 of the left front wheel. The supply pipe 20 is provided with a switching valve 40, which is a two-bow 1-2 position valve, which communicates with the brake pipe 21, 22 in the first position shown, and in a second position different from that shown. In each position the brake pipes 21, 22 are shut off.

With the above configuration, a normal braking action is performed, and at this time the switching valve 40 is in the first position.

Next, the configuration for performing the anti-skid control and the vehicle stop t5 control will be explained.

The pump 6 is driven by an electric motor 7, sucks brake oil from a branch 59 of an oil pipe 50 connected to a reservoir 8, and supplies this oil to each wheel cylinder 4, 5 through a supply pipe 60. The suction side and the discharge side of the pump 6 are connected by relief pipes 11 and 12, and a relief valve 10 is provided in the middle of these pipes. Relief valve IO is conduit 13
The pressure of the supply pipe 60 is guided through the pump 6, and the discharge pressure of the pump 6 is controlled to be below a set value in accordance with this pressure.

The branch pipe 61 of the supply pipe 60 can communicate with the branch pipe 23 of the brake pipe 21 via the control valve 41, and a check valve is provided in the middle of the supply pipe 60 to prevent brake fluid from flowing back from the control valve 41. 70 are provided. The control valve 41 is a three-bottom, two-position valve, and one discharge boat is connected to the branch pipe 23 and the other discharge boat is connected to the branch pipe 51 of the oil pipe 50. Thus, the control valve 41 causes the branch pipe 61 to communicate with the branch pipe 23 at the first position shown in the figure, and causes the branch pipe 23 to communicate with the branch pipe 51 at a second position different from the illustration.

Therefore, when the control valve 41 is in the first position, the pump 6
Brake oil discharged from the supply pipe 60 passes through the branch pipe 23 and is supplied to the wheel cylinder 4, and the control valve 41
position, the bubble inside the foil cylinder 4! The oil is released from the branch pipe 23 to the reservoir 8 through the oil pipe 50.

Similarly, the branch pipe G2 of the supply pipe GO can communicate with the branch pipe 24 of the brake pipe 22 via the control valve 42.
One discharge port i is connected to the branch pipe 24, and the other discharge port is connected to the branch pipe 52 of the oil pipe 50. Thus, the control valve 42 connects the special pipe 62 in the first position shown in the figure to the branch pipe 24 to guide the brake oil discharged from the pump 6 to the wheel cylinder 5, and moves it to a second position different from the one shown in the figure. A certain special pipe 24 is communicated with a branch pipe 52 to release the brake oil in the wheel cylinder 5 to the reservoir 8.

30 is a supply pipe for the rear wheels (not shown). The configuration of the piping system for the rear wheels is basically the same as that for the front wheels described above, except that there is a well-known provisioning valve in the middle of the piping (when the oil pressure exceeds a certain value, the mask cylinder 3
The only difference is that a brake oil is provided at a pressure lower than the discharge pressure of the brake fluid to the rear wheel cylinder.

Anti-skid control is performed when it is determined that any of the wheels is locked, in other words, when it is determined that the deceleration or slip rate of the wheels is too large. The deceleration and slip rate of the wheels are calculated by an electric control unit (ECU) 9 equipped with a microcomputer, and therefore a vehicle speed sensor (not shown) is provided near the wheels. When the ECU 9 determines to start anti-skid control, it switches the switching valve 40 from the first position to the second position, and then switches the control valves 41 and 42 according to the deceleration and slip rate of the wheels.

The operation of the apparatus of this embodiment will be explained with reference to FIG.

Note that although only the front two wheels will be described below, the rear two wheels also function in the same manner as the front two wheels.

First, regarding anti-skid control, in the non-operating state where no brake action is performed, the operating motor 7
is stopped, and the switching valve 40 and control valves 41, 42 are each in the first position. Therefore, when the brake pedal 1 is depressed, the pressure oil discharged from the master cylinder 3 is
Each wheel cylinder 4.5 through the brake pipe 21゜22
As a result, the pressure in these wheel cylinders increases rapidly, and the speed of the wheels decreases accordingly. Meanwhile, the speed of the vehicle body also begins to decrease, but the decrease in wheel speed is more rapid.

When the speed of the wheels becomes smaller than the reference speed, it is determined that the slip rate is increasing, and the ECU 9 outputs a command signal for anti-skid control. That is, the solenoid of the switching valve 40 is energized and the switching valve 40 is in the second position.
The pump 6 is switched to the position, and energization of the electric motor is started to start the pump 6. Then, in order to reduce the pressure in a given foil cylinder, the control valve 41, 42 corresponding to that foil cylinder is switched to the second position, and the brake fluid in this foil cylinder is passed through the oil line 50 to the reservoir. Released at 8. The pressure within the foil cylinder therefore begins to decrease. On the other hand, when the deceleration of the wheel decreases and it becomes necessary to increase the pressure in the wheel cylinder again, the control valve is switched to the first position. As a result, brake oil is supplied to the wheel cylinder via the branch pipes 61 and 62, and the wheel cylinder pressure increases.

Thereafter, the control valves 41, 42 are switched depending on the deceleration or slip rate of the wheels, and the pressure in the wheel cylinders 4, 5 is reduced or increased. The anti-skid control ends when the vehicle stops or the brake switch is turned off, and at this time the ECU 9 stops the electric motor 7 and switches the switching valve 40 to the first position.

Next, the vehicle stop maintenance control will be explained using the flowchart shown in FIG. 2.

First, in step 90, it is determined whether or not the wheel speed VW is lower than the set vehicle speed V, (for example, ■1-1kffl/h). If YES, in step 91, it is determined whether or not the brake pedal l is depressed. judge.

When both steps 90 and 91 are YES, it is determined that the vehicle is stopped, and in step 92, the solenoid of the switching valve 40 is energized to switch the switching valve 40 to the second position, thereby reducing the pressure in the wheel cylinders 4 and 5. Hold. Therefore, even if the brake pedal 1 is released, the braking state is maintained. Next, the process proceeds from step 92 to step 93, in which it is determined whether a pressure increase requirement has occurred. That is, in step 93,
When the vehicle moves due to insufficient braking force and a wheel speed signal is generated and the brake pedal 1 is being depressed, YES is determined, and otherwise, NO is determined. And step 9
If No in step 3, the process proceeds to step 94, where it is determined whether or not a starting operation has been performed. In this step 94, in the case of a torque converter type automatic transmission transmission, YES is determined when the shift lever is in the driving range position and the accelerator pedal is depressed, while in the case of a manual transmission, the shift lever is determined to be in the driving range position. Gear A
・When the clutch is in the position and the clutch is connected by a predetermined amount or more, it is judged as YES. And in this step 7 step 94 N
If it is determined as o, the process returns to step 93, while step 94
If it is determined YES in step 95, the switching valve 40 is
is switched to the first position, the pressure in the foil cylinders 4 and 5 is released, and the vehicle can start moving. Next, the process returns to step 90, and in step 90.91, it is again determined whether the vehicle is stopped.

By the way, if the determination in step 93 is YES, the process proceeds to step 96 where the switching valve 40 is switched to the first position, and at the same time, a timer is started in step 97. Step 98 determines No until the elapsed time after executing step 96 becomes equal to the set time 11 (for example, t, = 1 second), and if 1>1. If so, the determination is YES and the process returns to step 92. Therefore, during this time, the pressure in the wheel cylinders 4 and 5 can be increased by depressing the brake pedal l.

Note that step 93 in the above embodiment is
．． It is also possible to determine YES when the brake pedal 1 is once released and then depressed again during the Wi ring calculation in step 94.

Furthermore, although the above-mentioned embodiment shows an example that includes a vehicle stop maintenance function and an anti-skid function, the present invention can be applied to any device that has at least a vehicle vehicle stop maintenance function.

〔Effect of the invention〕

As explained above, by using the vehicle brake device of the present invention, it is possible to perform a good braking action when the vehicle is stopped without having problems such as deterioration in brake pedal operability or deterioration in anti-skid controllability. .

[Brief explanation of drawings]

FIG. 1 is a hydraulic piping diagram showing an embodiment of the present invention, and FIG. 2 is a flowchart showing the operation of the embodiment of the present invention. 3...Mask cylinder, 4,5...Foil cylinder. 40...Switching valve, 41.42...Control valve.

Claims (1)

[Scope of Claims] Pressure generating means that generates brake pressure when a brake pedal is depressed; braking means that is actuated by the brake pressure to generate braking force; and a valve that closes when the vehicle is stopped to establish communication between the two means. and a switching valve that shuts off, the switching valve being opened for a predetermined period of time when a pressure increase requirement occurs while the switching valve is closed.