JPS6339470B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a negative pressure source device for a negative pressure booster used to boost a brake master cylinder or the like in an automobile or other vehicle.

Conventionally, as a negative pressure source device for a negative pressure booster for a vehicle, a negative pressure outlet hole is provided in the intake system downstream of the throttle valve of an internal combustion engine, and the negative pressure chamber of the negative pressure booster is connected to this negative pressure outlet hole. A device is known in which the engine is connected via a check valve and the engine's intake negative pressure is stored in the negative pressure chamber as power for the booster.

By the way, depending on the type of internal combustion engine installed in the car and the type of its accessory equipment (for example, if the engine is a two-stroke type, if it is equipped with a multiple carburetor, or if it is equipped with an automatic transmission), The negative pressure used by the engine is very low, generally around -500 mmHg, but sometimes only around -300 to -400 mmHg can be obtained. In such cases, conventional methods have been to widen the pressure receiving area of the pressure receiving part of the booster to ensure a predetermined boost ratio, but this would lead to an increase in the size of the booster and would take up space in the engine room of the vehicle. This creates problems that make installation difficult.

The present invention has been proposed in view of the above, and even when the intake negative pressure of the internal combustion engine is low, by using an air ejector, the high negative pressure necessary for the operation of the negative pressure booster can be supplied to the negative pressure booster. Until the negative pressure in the device's negative pressure chamber reaches the magnitude of the engine's suction negative pressure, the engine's suction negative pressure is immediately supplied to the booster without relying on the air ejector, and the negative pressure is quickly accumulated. The purpose of the present invention is to provide a simple and effective negative pressure source device that requires less piping. An air ejector is configured by providing a decompression chamber, an outlet chamber connected to the air outlet, a diff user communicating between these two chambers, and a nozzle capable of ejecting air from the air inlet to the diff user in the decompression chamber, and The suction port is connected to a negative pressure outlet provided in the suction system downstream of the throttle valve of the engine, and the suction port is connected to a negative pressure chamber of a negative pressure booster. a bypass that communicates between the air outlet and the air outlet; a first check valve that is installed in the bypass to prevent negative pressure from flowing back toward the negative pressure outlet; and a first check valve that is installed in the suction port to prevent the negative pressure from flowing back toward the negative pressure outlet. A second check valve is provided to prevent backflow of negative pressure to the pressure outlet side.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. In FIG. 1, S is a known negative pressure booster for operating a brake master cylinder of an automobile, and is operated by a brake pedal Bp. A negative pressure chamber 3 is defined within a booster shell 1 of this booster S by a booster piston 2 with a diaphragm. Further, E is an internal combustion engine of an automobile, and its intake system 4 is composed of an intake manifold 5 and a carburetor 6 installed at its upstream end.
An air cleaner Ac is installed at the inlet of the intake path 6a of the carburetor 6.
is installed. The carburetor 6 has a throttle valve 7 as usual. A negative pressure outlet hole 8 is provided in the suction system 4 downstream of the throttle valve 7, and an air ejector 10 is provided in the negative pressure passage 9 connecting the negative pressure outlet hole 8 and the negative pressure chamber 3 of the booster S. is established as follows. still,
In the negative pressure passage 9, the section between the negative pressure outlet hole 8 and the air ejector 10 is called an upstream negative pressure passage 9a, and the section between the air ejector 10 and the negative pressure chamber 3 is called a downstream negative pressure passage 9b.

As shown in FIG. 2, the synthetic resin main body 11 of the air ejector 10 has a first connecting pipe 11a having an air inlet 12 and protruding from the front surface of the main body 11, and a first connecting pipe 11a having an air outlet 13 and protruding from the rear surface of the main body 11. The second one is more prominent.
A connecting pipe 11b, a third connecting pipe 11c having a suction port 14 and protruding from the side surface of the main body 11, and a suction port 14.
A decompression chamber 15 and an outlet chamber 16 which are connected to the air outlet 13, respectively, and a diffuser 17 which communicates between the two chambers 15 and 16 are provided. air inlet 1
2 is communicated with the atmosphere through the air passage 25 and the air cleaner Ac, and the air outlet 13 is connected to the downstream end of the upstream negative pressure passage 9a. Further, the suction port 14 is connected to the upstream end of the downstream negative pressure passage 9b.

In the illustrated example, the air passage 25 is connected to an air cleaner.
Although it is connected to Ac, it can also be connected to the vicinity of the inlet of the intake path 6a of the carburetor 6 (see the chain line in FIG. 1). In either case, the outside air purified by the air cleaner Ac is sucked into the air passage 25 as well as into the carburetor 6.

The diffuser 17 includes a tapered portion 18 formed on one end surface of the decompression chamber 15, a diverging taper portion 19 formed on one end surface of the outlet chamber 16, and both tapered portions 1.
It is connected to the throat part 20 that connects between 8 and 19,
In the decompression chamber 15, a nozzle 21 that is connected to the air inlet 12 and has a nozzle hole directed toward the throat 20 is provided in the tapered part 1.
8.

Further, the main body 11 is provided with a bypass 22 that bypasses the differential user 17 and connects the air outlet 13 and the suction port 14 and has a flow path resistance smaller than that of the differential user 17. A second check valve 24 is also provided at the suction port 14 .

The first check valve 23 is accommodated in a valve chamber 26 formed at a bend in the middle of the bypass 22.
The valve spring 27 urges the valve spring 27 to close the suction port 14 side of the valve 2. The first check valve 23 of the valve chamber 26
The insertion openings for these are closed by blind plugs 28 welded or glued to the main body 11. Further, the second check valve 24 is accommodated in a valve chamber 29 formed at a connection between the bypass 22 and the suction port 14, and is biased by a valve spring 30 so as to close the suction port 14. The insertion opening for the second check valve 24 and the like in the valve chamber 29 is closed by the third connecting pipe 11c welded or connected to the main body 11. In this way, the first and second check valves 23 and 24 are both configured to prevent the backflow of negative pressure from the negative pressure chamber 3 side to the negative pressure extraction hole 8 side, and are also configured to prevent negative pressure from flowing backward from the negative pressure chamber 3 side to the negative pressure extraction hole 8 side. Unitized.

Next, the operation of this embodiment will be explained.

Now, when the internal combustion engine E is started and negative pressure is generated in the suction system 4 downstream of the throttle valve 7, this suction negative pressure is taken out from the negative pressure outlet hole 8 and passes through the upstream negative pressure passage 9a to the outlet chamber. 16 and bypass 22. Then, the negative pressure acting on the bypass 22 opens the first check valve 23 and proceeds to the downstream negative pressure passage 9b,
Next, the second check valve 24 is opened, and the liquid reaches the negative pressure chamber 3 of the booster S and is stored there.

On the other hand, the negative pressure acting on the outlet chamber 16 passes through the diffuser 17 and acts on the nozzle 21, and the suction force of this negative pressure causes the nozzle 21 to flow through the air cleaner.
Outside air purified by AC is sucked in through the air inlet 12 and injected toward the diffuser 17 to generate a high-speed jet of air. As a result, the pressure in the decompression chamber 15 is reduced, and air is sucked in through the suction port 14. The downstream negative pressure passage 9b is further reduced in pressure, that is, the negative pressure in the negative pressure chamber 3 is increased. Then, when the suction negative pressure in the decompression chamber 15 becomes higher than the suction negative pressure of the engine E, the first check valve 23 is closed, so that the negative pressure in the decompression chamber 15 is reliably supplied to the negative pressure chamber 3 without being short-circuited to the bypass 22. will be introduced in Thus, the negative pressure chamber 3 stores a total negative pressure of the negative suction pressure of the engine E and the negative suction pressure of the air ejector 10.

If the suction negative pressure of the engine E suddenly decreases or disappears due to acceleration of the engine E or stoppage of the engine E by rapidly opening the throttle valve 7, the pressure reducing function of the air ejector 10 will decrease or stop. Since the second check valve 24 closes immediately, the negative pressure in the negative pressure chamber 3 is prevented from flowing back through the negative pressure passage 9.

As described above, according to the present invention, a main body having an air inlet, an air outlet, and a suction port opened on the outer surface, a decompression chamber connected to the suction port, an outlet chamber connected to the air outlet, a diffuser communicating between these two chambers, and a nozzle capable of ejecting air from an air inlet toward a differential user in a decompression chamber to constitute an air ejector, and the air outlet is connected to a negative pressure outlet hole provided in an intake system downstream of a throttle valve of the internal combustion engine, In addition, since the suction ports are connected to the negative pressure chambers of the negative pressure booster, the air ejector is actuated by the engine's suction negative pressure, and a suction higher than the engine's suction negative pressure is generated in the air ejector's decompression chamber. Negative pressure can be applied to the negative pressure chamber of the booster, and a desired boost ratio can be obtained without particularly expanding the pressure receiving area of the pressure receiving part of the booster. Furthermore, since there is no need to provide a special fluid pump to drive the air ejector, the configuration is simple and the negative pressure source device can be provided at low cost.Furthermore, since there are no moving parts, there are fewer failures.

Further, a bypass is provided in the main body to bypass the differential user and communicate between the suction port and the air outlet,
This bypass is equipped with a first check valve that prevents negative pressure from flowing back into the negative pressure outlet, so that after the engine is started, the negative pressure in the negative pressure chamber of the booster is equal to or lower than the engine suction negative pressure. Until this size is reached, the intake negative pressure of the engine is quickly supplied to the negative pressure chamber of the booster mainly through the bypass, which has a small flow path resistance, and the negative pressure in the negative pressure chamber can be quickly increased. , the operational state of the booster can be established early, and when the suction negative pressure of the air ejector becomes higher than the suction negative pressure of the engine, the suction negative pressure of the air ejector is reduced by closing the first check valve. to prevent short circuits to the pressure bypass,
This can be reliably supplied to the negative pressure chamber of the booster.

Furthermore, since the suction port is provided with a second check valve that prevents negative pressure from flowing back toward the negative pressure outlet side,
When the intake negative pressure of the engine decreases or disappears, the second check valve is closed to prevent the negative pressure from flowing back from the negative pressure chamber to the negative pressure passage, thereby preventing the negative pressure in the negative pressure chamber from decreasing. can do.

Furthermore, since the first and second check valves are provided in the main body of the air ejector, the air ejector and both check valves are integrated into a unit, and a special check valve is provided for connecting the air ejector and each check valve. No piping required,
This can contribute to further simplifying the structure and reducing costs.

[Brief explanation of drawings]

FIG. 1 is a schematic side view showing one embodiment of the device of the present invention, and FIG. 2 is an enlarged longitudinal sectional side view of an air ejector, which is a main part thereof. E... Internal combustion engine, S... Negative pressure booster, 3... Negative pressure chamber, 4... Suction system, 7... Throttle valve, 8... Negative pressure outlet, 9
... Negative pressure passage, 9a... Upstream negative pressure passage, 9b... Downstream negative pressure passage, 10... Air ejector, 11... Main body, 12
...Air inlet, 13...Air outlet, 14...Suction port, 1
5... Decompression chamber, 16... Outlet chamber, 17... Diffuser, 21... Nozzle, 22... Bypass, 23... First
Check valve, 24...second check valve.

Claims (1)

[Claims] 1 A main body 11 having an air inlet 12, an air outlet 13, and a suction port 14 opened on the outer surface, a decompression chamber 15 connected to the suction port 14, and an outlet chamber 1 connected to the air outlet 13.
6. The air ejector 10 is configured by providing a diff user 17 that communicates between these two chambers 15 and 16, and a nozzle 21 capable of ejecting air from the air inlet 12 toward the diff user 17 in the decompression chamber 15. is connected to a negative pressure outlet 8 provided in the suction system 4 downstream of the throttle valve 7 of the internal combustion engine E, and the suction port 14 is connected to the negative pressure chamber 3 of the negative pressure booster S, and furthermore, the main body 11, Def user 1
a bypass 22 that communicates between the suction port 14 and the air outlet 13 by bypassing 7; a first check valve that is interposed in the bypass 22 and prevents negative pressure from flowing back toward the negative pressure take-off hole 8 side; 23, and a second check valve 24 which is interposed in the suction port 14 and prevents negative pressure from flowing back toward the negative pressure outlet 8 side. .