JPS6230832Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a vacuum booster that uses both negative pressure and positive pressure for use in vehicles such as automobiles and forklifts.

A conventional vacuum booster is a device that uses a power piston to increase the hydraulic pressure generated in the master cylinder by the driver's brake pedal depression force to generate a large braking force even with a light pedal effort. There is an atmospheric pressure type known from Japanese Utility Model Application Publication No. 56-27163, which operates with the negative pressure generated during the intake stroke of the engine or the differential pressure between the negative pressure generated in a vacuum pump and atmospheric pressure, and the atmospheric pressure type known from Japanese Utility Model Application Publication No. 56-27163. There is a positive pressure type that operates with a pressure difference of . Further, as shown in FIG. 1, in the case where the power cylinder 100 and the master cylinder 101 are integrated, the power cylinder 100
The low pressure chamber of the engine intake manifold
In some circuits connected to the intake manifold, a vacuum pump 103 is provided for the purpose of supplementing the negative pressure generated by the intake manifold. In other words, power cylinder 10
The pressure switch 104 detects the lack of negative pressure in the low pressure chamber at 0, rotates the motor 105, reciprocates the diaphragm 107 via the eccentric cam 106, and alternately supplies air flow to the check valves 108 and 109. This is to ensure an appropriate negative pressure in the low pressure chamber. 110 is a filter. In order to further reduce driver fatigue and improve braking performance, a vacuum booster that applies both negative and positive pressure to both sides of the power piston has also been proposed. There is.

However, in the case of conventional vacuum boosters that combine negative pressure and positive pressure, the compressor for obtaining positive pressure was installed separately, so the space for installing the compressor was secured within the narrow bonnet. Not only is this a difficult task, but there is also the problem that the cost is higher than if the same boosting ratio was obtained by enlarging an atmospheric pressure type vacuum booster.

The present invention was developed in view of these conventional problems, and is an atmospheric pressure type vacuum booster equipped with a vacuum pump. The purpose is to solve the above problems by using a pressure/positive pressure type vacuum booster.

The present invention will be specifically described below with reference to embodiments shown in the drawings.

In FIG. 2, reference numeral 1 denotes a power cylinder, which together with a master cylinder 2 constitutes a hydraulic pressure generator. The inside of the power cylinder 1 is divided into a low pressure chamber A and a high pressure chamber B by a power piston 3 and a diaphragm 4. ing. Low pressure chamber A includes low pressure side piping 30a, 30
b, the vacuum pump 6 is connected via the first electromagnetic switching valve 5.
Connect to the suction port 6a of the

The first electromagnetic switching valve 5 communicates the suction port 6a of the vacuum pump 6 with the atmosphere via the low pressure chamber A or the filter 8 by switching the first electromagnetic switching valve 5. The vacuum pump 6 rotates the eccentric cam 6d by driving the motor 6c,
It reciprocates the diaphragm 6e to generate an air flow from the suction port 6a toward the discharge port 6b.
6g are each check valves. Further, the discharge port 6b of the vacuum pump is connected to the second electromagnetic switching valve 7 through a low-pressure/high-pressure side pipe 30c. By switching, the second electromagnetic switching valve 7 communicates with the pressure tank 9 or the intake manifold X of the engine, which connects the discharge port 6b of the vacuum pump with the high pressure side piping 30d. The pressure accumulation tank 9 is connected to the high pressure chamber B via the on-off valve 10, which is activated by pressing a predetermined amount of the brake pedal 14, at the high pressure side piping 30e. Reference numeral 11 designates a first pressure switch provided on the low pressure side piping 30a, which closes its contacts when the pressure in the low pressure chamber A rises above the set negative pressure _P1 , and opens its contacts when the set negative pressure _P1 is reached. Reference numeral 12 designates a second pressure switch provided on the high pressure side piping 30e, which closes its contacts when the pressure in the accumulator tank 9 drops below the set positive pressure _P2 , and opens its contacts when the set positive pressure _P2 is reached.

Next, the effect will be explained. During non-braking, the on-off valve 10 is always closed and the high pressure chamber B communicates only with the low pressure chamber A. In other words, low pressure chamber A and high pressure chamber B
The two are communicated with each other through the vent hole 3a of the power piston 3 and have the same pressure, and the power piston 3 is located on the right side of the figure due to the action of the return spring 13.
With the first switching valve 5 blocking the atmospheric side and the second switching valve 7 blocking the pressure storage tank 9 side, the intake manifold X of the engine (not shown) lacks suction negative pressure, and the pressure inside the low pressure chamber A increases. When the negative pressure rises above the set negative pressure _P1 , the first pressure switch 11 is turned on, and the vacuum pump 6 is driven while the first switching valve 5 and the second switching valve 7 remain unchanged. When the pressure in the low pressure chamber A returns to the set negative pressure _P1 , the first pressure switch 11 is turned off,
The operation of the vacuum pump 6 is stopped.

When the inside of the low pressure chamber A is at the set negative pressure _P1 and the pressure accumulator tank 9 is lower than the set positive pressure _P2 , the second pressure switch 12 is turned on and the first switching valve 5 is switched to establish a vacuum. The suction port 6a of the pump is communicated with the atmosphere, the second switching valve 7 shuts off the intake manifold X side, and the vacuum pump 6 is driven. The vacuum pump 6 functions as a compressor and stores pressurized air in the pressure storage tank 9. When the pressure accumulation tank 9 reaches the set positive pressure _P2 , the second pressure switch 12 is turned off to stop the operation of the vacuum pump 6, and the first switching valve 5 is turned off.
shuts off the atmospheric side, and the second switching valve 7 closes off the pressure accumulator tank 9.
The side is shut off in preparation for braking.

Incidentally, if both the first pressure switch 11 and the second pressure switch 12 satisfy the on-operation condition, the first pressure switch 11 and the second pressure switch 12
Priority is given to turning on the pressure switch 11, and the low pressure chamber A is
First, ensure the set negative pressure _P1 . Each of the above controls is performed by a microcomputer (not shown).

During braking, when the brake pedal 14 is depressed, the operating rod 15, valve plunger 16, and poppet valve 17 move to the left in the figure, and the poppet valve 17 is seated on the seat of the power piston 3 under the force of the poppet spring 18. Close the vacuum valve 3b. When the brake pedal 14 is further depressed to a predetermined amount, the valve plunger 16 separates from the poppet valve 17, and the third valve plunger 16 separates from the poppet valve 17.
As shown in detail in the figure, the on-off valve 10 opens, and the high pressure chamber B reaches the set positive pressure _P2 . As a result, a pressure difference is created between the low pressure chamber A and the high pressure chamber B, and the power piston 3 is pushed to the left in the figure against the force of the return spring 13, pushing the piston 21 via the push rod 20 and pushing the master cylinder 2. generates pressure oil. In this case, the area of the piston 21 of the master cylinder is S ₁ and the area of the power piston 3 is S ₂ ,
The boost ratio is S ₂ /S ₁ (P ₂ −P ₁ ).

If both the first pressure switch 11 and the second pressure switch 12 satisfy the on-operation condition during braking,
Since priority is given to the operation of the first pressure switch 11, the set negative pressure _P1 of the low pressure chamber A can be secured. Further, the pressure accumulating tank 9 can be provided with a check valve that opens when the pressure in the tank 9 is lower than atmospheric pressure P ₀ . In this case, the pressure difference between the chambers A and B is at least P ₀ -P ₁ , and the function as an atmospheric pressure type vacuum booster can be reliably obtained.

FIG. 4 shows another embodiment. In this embodiment, a vane pump directly driven by an engine (not shown) is installed as the vacuum pump 22, and a first electromagnetic switching valve 5 and a second electromagnetic switching valve are connected to the low pressure chamber A and high pressure chamber B of the power cylinder 1. The arrangement of the valve 7, the on-off valve 10, the first pressure switch 11, the second pressure switch 12, and the pressure accumulator tank 9 is the same as in the previous embodiment. However, the connection port 7a of the second electromagnetic switching valve 7 can be used instead of connecting to the engine intake manifold, if the efficiency of the vacuum pump 22 is slightly sacrificed.
It can communicate with the atmosphere.

The vacuum pump 22 in this embodiment is always in operation while the engine is running, and the first pressure switch 11 operates with priority over the second pressure switch 12.
detects that the pressure in the low pressure chamber A has risen above the set negative pressure _P1 , and shuts off the filter 8 side of the first electromagnetic switching valve 5, that is, the atmospheric side, and shuts off the pressure accumulation tank of the second electromagnetic switching valve 7. The second pressure switch 12 detects that the pressure in the pressure storage tank 9 is lower than the set positive pressure P ₂ and switches the first electromagnetic switching valve 5 off. Shutoff of low pressure chamber A side, 2nd
It is only necessary to have a function of transmitting an electric signal to respectively shut off the atmospheric side connection port 7a of the electromagnetic switching valve 7. still,
For safety, a safety valve 23 can be provided to limit the internal pressure of the pressure storage tank 9 to _P2 .

Also in this embodiment, the first pressure switch 11,
The first and second pressure switches based on the operation of the second pressure switch 12
By microcomputer control of the electromagnetic switching valves 5 and 7, the same effects as in the previous embodiment can be obtained.

It goes without saying that the present invention can also be applied to a hydraulic pressure generator in which a power cylinder and a master cylinder are separate bodies.

As explained above, according to the present invention, the inside of the power cylinder is divided into a low-pressure chamber and a high-pressure chamber by the power piston, and when the operating pedal is depressed, the low-pressure chamber and the high-pressure chamber are isolated and the both chambers are separated. In a vacuum booster that generates a pressure difference to advance the power piston and push rod to generate pressure oil in the master cylinder, the low pressure chamber of the power cylinder and the suction port of the vacuum pump are communicated with the low pressure chamber or the atmosphere. a first electromagnetic switching valve that switches to communicate or disconnect the vacuum pump and the discharge port of the vacuum pump and the pressure accumulation tank;
The pressure accumulator tank, an on-off valve that opens and closes when the operating pedal is depressed a predetermined amount to communicate or cut off the high pressure chamber and the pressure accumulator tank, and the high pressure chamber of the power cylinder are connected in series with piping, and A first electromagnetic switching valve and a second electromagnetic switching valve are configured to detect that the pressure in the low pressure chamber has risen above a set pressure, and to connect the suction port of the vacuum pump and the low pressure chamber and to cut off the discharge port of the vacuum pump and the pressure accumulation tank. A first pressure switch that operates an electromagnetic switching valve, and a first pressure switch that detects that the pressure in the pressure storage tank has fallen below a set pressure, communicates the suction port of the vacuum pump with the atmosphere, and connects the discharge port of the vacuum pump and the pressure storage tank. A second pressure switch for operating the first electromagnetic switching valve and the second electromagnetic switching valve is provided so that the first pressure switch operates with priority over the second pressure switch, and the first electromagnetic switching valve and the second pressure switch are provided in communication with each other.
The configuration is such that it controls an electromagnetic switching valve.

Therefore, the atmospheric air introduction in conventional atmospheric pressure type vacuum boosters has been changed to positive pressure introduction, and it functions as a negative pressure/positive pressure type vacuum booster, and a dedicated compressor to obtain positive pressure is required. without providing
A large boost ratio can be obtained, and a stronger braking effect can be obtained with a compact structure and low cost.

[Brief explanation of the drawing]

Figure 1 is a system diagram of a conventional vacuum booster, Figure 2
The figure is a system diagram showing an embodiment of the present invention, and Figure 3 is an explanatory diagram of the operation of the valve plunger and poppet valve.
FIG. 4 is a system diagram showing another embodiment of the present invention. 1: Power cylinder, 2: Master cylinder,
3: power piston, 5: first electromagnetic switching valve, 6,
22: Vacuum pump, 6a: Suction port, 6b: Discharge port, 7: Second electromagnetic switching valve, 9: Pressure accumulator tank, 1
0: Open/close valve, 11: First pressure switch, 12: Second pressure switch, 14: Brake pedal (operating pedal), 20: Push rod, A: Low pressure chamber,
B: High pressure chamber, X: Intake manifold.

Claims (1)

[Scope of utility model registration request] The inside of the power cylinder is divided into a low pressure chamber and a high pressure chamber by the power piston, and when the operating pedal is depressed, the low pressure chamber and the high pressure chamber are isolated and a pressure difference is created between the two chambers to advance the power piston and the push rod. In a vacuum booster that generates pressure oil in a master cylinder, the first electromagnetic switching valve switches the low pressure chamber of the power cylinder and the suction port of the vacuum pump to communicate with the low pressure chamber or the atmosphere, and the vacuum pump. , a second electromagnetic switching valve that connects or disconnects the discharge port of the vacuum pump and the pressure accumulation tank; An on-off valve that communicates or shuts off communication and the high-pressure chamber of the power cylinder are connected in series with piping, and when the pressure in the low-pressure chamber rises above the set pressure, the suction port of the vacuum pump and the low-pressure chamber are connected in series. a first pressure switch that operates a first electromagnetic switching valve and a second electromagnetic switching valve so as to communicate with each other and to cut off the discharge port of the vacuum pump and the pressure accumulation tank; a second pressure switch that detects the pressure and operates the first electromagnetic switching valve and the second electromagnetic switching valve so as to communicate the suction port of the vacuum pump with the atmosphere and communicate the discharge port of the vacuum pump with the pressure storage tank; A vacuum booster characterized in that the first pressure switch is provided to operate with priority over the second pressure switch to control the first electromagnetic switching valve and the second electromagnetic switching valve.