JPH0742899Y2 - Brake booster for automobile - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION INDUSTRIAL APPLICATION Field of the Invention The braking booster for an automobile of the present invention is mainly used for a braking device for a small to medium-sized automobile such as a passenger car.

2. Description of the Related Art In order to reduce the fatigue of a driver, a brake booster that reduces the pedaling force of a brake pedal may be provided in a braking device of an automobile. As the operating pressure of the braking booster, pressurized air generated by an air compressor is used in large vehicles such as trucks, and is generated by a vacuum pump or intake manifold in small to medium vehicles such as passenger cars. A vacuum is used.

A braking device having a braking booster using a vacuum pump is provided, for example, from a master cylinder 2 operated by a brake pedal 1 to each wheel, as shown in the drawings of an embodiment of the present invention.・ A master back 5 is inserted in the middle of the brake pipe 4 that sends the working fluid, generally working oil, to the cylinder 3.
Installed in the power cylinder 6
The piston is moved by the pressure difference between the negative pressure generated by the vacuum pump 10 and the atmospheric pressure, and the hydraulic piston built in the hydraulic cylinder 7 and connected to the power piston is operated. Has been done. The hydraulic piston is provided with a check valve to allow the working fluid sent from the master cylinder 2 to flow to the wheel cylinder 3 and to
Wheel / cylinder 3 to stop backflow when the piston operates
Increase the working fluid delivered to. Therefore, even if the brake pedal 1 is stepped on with a small stepping force, a large braking force can be transmitted to the wheel cylinder 3.

Problems to be solved by the invention The vacuum pump 10 is constantly driven by an engine-driven generator 11 (usually an AC generator) during engine operation, and a vacuum pipe connecting the suction port and the power cylinder 6 Negative pressure is stored in the surge tank 13 installed in the middle of 12. And
During braking, the power piston operates at a pressure difference between the negative pressure of the surge tank 13 and the atmospheric pressure.

In this case, when the negative pressure stored in the surge tank 13 becomes high and becomes close to the maximum degree of vacuum that can be generated by the vacuum pump 10, the vacuum pump 10 causes cavitation, which not only causes noise higher than engine noise but also causes the vacuum pump 10 to generate noise. It causes vibration and corrosion on itself.

Therefore, the present invention has been devised for the purpose of providing a braking booster for an automobile, which is provided with means for preventing the negative pressure of the surge tank from increasing above a certain value, and therefore does not generate high noise.

MEANS FOR SOLVING THE PROBLEMS The present invention is a vacuum pump in which a master-back power cylinder installed in the middle of a brake pipe for sending a working fluid from a master cylinder to a wheel cylinder is constantly driven by an engine. In a braking booster for automobiles in which the negative pressure stored in the surge tank is used as the working pressure, an air conduit having an on-off valve is connected to the surge tank so that the negative pressure in the surge tank exceeds a certain value. The opening negative pressure is slightly closed and the negative pressure is closed.

Action It is the same as in the past that the working fluid sent from the master cylinder to the wheel cylinders attached to each wheel is increased by the master back to reduce the pedaling force of the brake pedal. When the surge tank, which stores the negative pressure generated by the vacuum pump, has a negative pressure above a certain level, generally -600 mmHg or more, the noise of the vacuum pump rises sharply and the maximum vacuum level that the vacuum pump can generate, that is, Generally, the noise becomes maximum when the temperature reaches about −700 mmHg and these are in a negative pressure equilibrium state.

According to the present invention, when the vacuum pump suddenly increases the noise level to a vacuum level of, for example, −600 mmHg, the negative pressure switch attached to the surge tank is activated and a signal from this is sent to the solenoid to turn on / off the valve. Open with and introduce air to close when the negative pressure drops a little. Alternatively, the negative pressure of the surge tank is made to act on the actuator to open the on-off valve at the negative pressure, and air is introduced to close the negative pressure when the negative pressure drops a little.

The degree of negative pressure reduction is set appropriately in consideration of the noise reduction effect and the maintenance of the driving force of the master / back. When the degree of vacuum when the on-off valve is opened is reduced by about 5-10 mmHg, the opening / closing is performed. Close the valve.

Effect of the Invention According to the present invention, when the negative pressure of the surge tank that stores the negative pressure generated by the vacuum pump and activates the master back during braking exceeds a certain value, air is introduced, so the vacuum pump is generated. Maintaining a negative pressure lower than the maximum possible vacuum degree prevents the vacuum pump and the surge tank from being in a negative pressure equilibrium state, that is, the maximum vacuum state, which causes a high noise and causes the vacuum pump to vibrate. The inconvenience of corrosion and corrosion is eliminated. Further, since the air introduction is stopped when the negative pressure is slightly reduced by the air introduction, the negative pressure of the surge tank can be maintained within a range that does not impair the braking boosting function.

Embodiment An embodiment of the present invention will be described with reference to the drawings. A braking pipe 4 for sending a working fluid from a master cylinder 2 connected to a brake pedal 1 to a wheel cylinder 3 attached to each wheel.
A master back 5 is installed in the middle of. Master·
The back 5 is a power cylinder 6 and a hydraulic cylinder 7 that is driven by the power cylinder 6 to increase the working fluid.
And the air inside the air cleaner 14 to the power cylinder 6
And a relay valve 8 which acts on one surface of the power piston incorporated in the. When a working fluid is sent from the master cylinder 2 to the hydraulic cylinder 7, a part of the relay valve 8 acts on the relay valve 8. It acts to open the valve, and air is introduced through the air pipe 9 as described above.

A surge tank 13 and a check valve 15 are installed in a vacuum pipe 12 that connects a power cylinder 6 with an inlet of a vacuum pump 10 that is constantly driven by an engine-driven generator 11 during engine operation. Check valve 15 when vacuum pump 10 stops
Is closed and the negative pressure in the surge tank 13 is maintained. The negative pressure of the surge tank 13 acts on the other surface of the power piston, and the power piston is activated by the pressure difference from the atmospheric pressure to activate the hydraulic piston built in the hydraulic cylinder 7. To increase the working fluid.

An air conduit 16 opened to the inside of the air cleaner 14 is connected to the surge tank 13, and a throttle made of an orifice that restricts the air flow rate near the connection port to the surge tank 13.
17 are provided.

In the embodiment shown in FIG. 1, an electromagnetically driven on-off valve 18 is provided in the air conduit 16 and a negative pressure switch 20 is additionally provided in the surge tank 13. When the surge tank 13 has a negative pressure over a preset constant value, the negative pressure switch 20 operates, and an electric signal from this is sent to the solenoid 19 to open the on-off valve 18, and the surge tank 13 via the throttle 17 is opened. A small amount of air is introduced into to reduce the negative pressure. When the negative pressure drops a little below a preset constant value, the negative pressure switch 20 becomes inoperative and the on-off valve 18 closes.

In the embodiment shown in FIG. 2, an opening / closing valve 21 driven by a negative pressure is provided in the air conduit 16, and a diaphragm type or piston type negative pressure mechanism 22 is provided.
Is connected to the surge tank 13 by an operation conduit 23, and when the surge tank 13 has a negative pressure above a predetermined value, the negative pressure mechanism 22 operates to open the on-off valve 21 and throttle it.
A small amount of air is introduced into the surge tank 13 via 17 to reduce the negative pressure. When the negative pressure falls a little below a preset constant value, the negative pressure mechanism 22 becomes inoperative and the on-off valve 21 closes.

[Brief description of drawings]

FIG. 1 is a layout view showing an embodiment of the present invention, and FIG. 2 is a layout partial view showing a different embodiment of the present invention. 2 …… Master cylinder, 3 …… Wheel cylinder, 4…
… Brake piping, 5 …… Master back, 6 …… Power cylinder, 10 …… Vacuum pump, 12 …… Vacuum piping, 13 …… Surge tank, 16 …… Air conduit, 18,21 …… Open / close valve,

Claims (1)

[Scope of utility model registration request] 1. A power cylinder (6) of a master back (5) installed in the middle of a brake pipe (4) for sending a working fluid from a master cylinder (2) to a wheel cylinder (3) is constantly operated by an engine. Driven vacuum pump (1
In the braking booster for automobiles, which uses the negative pressure generated in the surge tank (13) and stored in the surge tank (13) as an operating pressure, an air conduit (1) having an opening / closing valve (18, 21) in the surge tank (13).
6) is not connected, and the on-off valves (18, 21) are configured to open when the negative pressure in the surge tank (13) exceeds a certain value, introduce air, and close when the negative pressure drops a little. Braking booster for automobiles.