JPS6339471B2 - - 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 a 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 engine's The negative pressure used is very low, generally around -500 mmHg, but sometimes only around -300 to -400 mmHg can be obtained. In such cases, the conventional method is to widen the pressure receiving area of the pressure receiving part of the booster to ensure a predetermined boost ratio. This creates a problem that makes installation in a room etc. difficult.

The present invention has been proposed in view of the above, and uses an air ejector to supply a high negative pressure necessary for its operation to a negative pressure booster even when the intake negative pressure of an internal combustion engine is low. 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. It is an object of the present invention to provide a simple and effective negative pressure source device that can reliably prevent fuel in the intake system from entering the booster even if there is a blowback phenomenon in the engine. The main body has an air inlet, an air outlet, and a suction port on its outer surface, a decompression chamber connected to the suction port, an exit chamber connected to the air outlet, a diffuser that communicates 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 provided in an intake system downstream of a throttle valve of the internal combustion engine, In addition, the suction ports are connected to the negative pressure chambers of a negative pressure booster, and a backflow of negative pressure to the negative pressure outlet side is provided to a bypass that communicates between the suction port and the air outlet, bypassing the diffuser. A first check valve is provided to prevent negative pressure from flowing back toward the negative pressure outlet, and a second check valve is provided to the suction port to prevent negative pressure from flowing back toward the negative pressure outlet. The valve, the first check valve, and the air outlet are arranged in this order from above.

Embodiments of the present invention will be described below with reference to the drawings. First, in FIGS. 1 and 3 showing the first embodiment, S is a known negative pressure booster for operating the brake master cylinder M of an automobile. It is operated by the 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, and an air cleaner Ac is installed at the entrance of the intake path 6a of the carburetor 6. .
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 this throttle valve 7, and the engine E is taken out from this negative pressure outlet hole 8.
The suction negative pressure is introduced into the negative pressure chamber 3 of the booster S through the negative pressure passage 9 and the air ejector 10.

As clearly shown in FIG. 3, the main body 11 of the air ejector 10 is made of synthetic resin, and a connecting boss 11d protruding from one side thereof is welded to the upper front surface of the booster shell 1.

A suction port 14 connected to the negative pressure chamber 3 is bored in the booster shell 1 at the connection portion with the connection boss 11d.

On the other hand, the main body 11 of the air ejector 10 has an air inlet 12 and a first inlet protruding from the upper surface of the main body 11.
The main body 11 has a connecting pipe 11a and an air outlet 13.
A second connecting pipe 11b protruding from the lower surface, a decompression chamber 15 and an outlet chamber 16 connected to the suction port 14 and the air outlet 13, respectively, and a diffuser 17 communicating between the two chambers 15 and 16 are provided. The air inlet 12 is connected to the air passage 25 and the air cleaner.
The air outlet 13 is connected to the negative pressure outlet 8 via the negative pressure passage 9.

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, an unwidened 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 opening of the valve chamber 26 is located in the main body 1.
It is closed by a blind plug 28 welded or glued to 1. Further, the second check valve 24 is accommodated in a valve chamber 29 formed to open at the end surface of the connecting boss 11d of the main body 11, and is biased by a valve spring 30 to close the suction port 14. The opening of the valve chamber 29 is connected to the booster shell 1 in which the suction port 14 is bored.
Closed by. Therefore, the portion of the booster shell 1 facing the second check valve 24 is the valve seat 3.
1.

In this way, the first and second check valves 23, 24
are configured to prevent backflow of negative pressure from the negative pressure chamber 3 side to the negative pressure outlet hole 8 side, and in order from the top are the air inlet 12, the second check valve 24, and the first check valve. 23 and an air outlet 13 are arranged.

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 sent to the negative pressure passage 9.
through which it acts on the outlet chamber 16 and the bypass 22.
Then, the negative pressure acting on the bypass 22 opens the first check valve 23 and proceeds, then opens the second check valve 24, reaches the negative pressure chamber 3 of the booster S through the suction port 14, and then reaches there. is stored in

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. to increase the negative pressure in the negative pressure chamber 3. If the suction negative pressure of the decompression chamber 15 becomes higher than the suction negative pressure of the engine E, the first check valve 2
3 is closed, the negative pressure in the reduced pressure chamber 15 is reliably introduced into the negative pressure chamber 3 without being short-circuited to the bypass 22. 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.

Even if the fuel flowing through the suction system 4 enters the negative pressure passage 9 due to the blowback phenomenon of the engine E, the ejector 10 will open the air inlet 12, the second check valve 24, the first check valve 23, and the Since the air outlet 13 is arranged, the fuel will not reach the suction port 14 due to natural flow, and even if the fuel passes through the differential user 17 or the first check valve 23, it will not reach the second check valve. 24, and when the first check valve 23 is opened due to the suction negative pressure of the engine E, the air is sucked into the suction system 4 along with a downward airflow.

FIG. 4 shows a second embodiment of the present invention, in which the connecting boss 11 of the previous embodiment is attached to the main body 11 of the ejector 10.
A connecting flange 11e is integrally formed in place of d,
This connecting flange 11e is superimposed on the front surface of the booster shell 1 via the seal ring 32, and the screw 3
3. The rest of the structure is the same as that of the previous embodiment, and in FIG. 4, parts corresponding to those of the previous embodiment are given the same reference numerals.

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, Further, the suction ports are respectively connected to the negative pressure chambers of the negative pressure booster, and the backflow of negative pressure to the negative pressure take-off hole side is caused to bypass the diffuser and communicate between the suction ports and the air outlet. Since a first check valve is installed to prevent negative pressure from flowing back into the suction port, and a second check valve is installed at the suction port to prevent negative pressure from flowing back toward the negative pressure outlet, air is By operating the ejector, suction negative pressure higher than the engine's suction negative pressure generated in the decompression chamber can be applied to the negative pressure chamber of the booster, without having to particularly expand the pressure receiving area of the pressure receiving part of the booster. With both, it is possible to obtain the desired boost ratio. 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. In addition, after the engine starts, until the negative pressure in the negative pressure chamber of the booster reaches the magnitude of the engine's intake negative pressure, the intake negative pressure of the engine is mainly transferred to the negative pressure of the booster through the bypass, which has a small flow resistance. supply the room promptly,
The negative pressure in the negative pressure chamber could be raised quickly, the booster could be ready for operation, and the suction negative pressure of the air ejector became higher than the engine suction negative pressure. Sometimes, by closing the first check valve, it is possible to prevent the suction negative pressure of the air ejector from shorting to the bypass, to ensure that it is supplied to the negative pressure chamber of the booster, and also to prevent the suction negative pressure of the engine from being short-circuited to the bypass. When the pressure 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. .

Furthermore, the air inlet, the second check valve, the first
Since the check valve and the air outlet are arranged in this order from above, even if the fuel in the intake system passes through the differential user or the first check valve due to engine blowback, the fuel will flow through the first check valve. The air is immediately discharged to the air outlet side by the downward airflow when the valve is opened, and is reliably prevented from entering the booster.

[Brief explanation of drawings]

Fig. 1 is a schematic side view showing a first embodiment of the device of the present invention, Fig. 2 is an enlarged partial longitudinal sectional side view of the main parts of the booster and air ejector, and Fig. 3 is an enlarged partial longitudinal side view of the air ejector. Further enlarged vertical side view, No. 4
The figure is a side view similar to FIG. 2, showing a second embodiment of the device of the present invention. 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, 10... Air ejector, 11... Main body,
12... Air inlet, 13... Air outlet, 14... Suction port, 15... Decompression chamber, 16... Outlet chamber, 17... Diffuser, 21... Nozzle, 22... Bypass, 23...
1st check valve, 24...2nd 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 13, 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. A first check valve 23 is installed in a bypass 22 that bypasses the suction port 14 and communicates between the suction port 14 and the air outlet 13, and that prevents negative pressure from flowing back toward the negative pressure take-off hole 8 side. 1
4 is interposed with a second check valve 24 that prevents negative pressure from flowing back toward the negative pressure outlet hole 8, and the air inlet 12,
Second check valve 24, first check valve 23 and air outlet 1
A negative pressure source device for a negative pressure booster for a vehicle, comprising: 3 arranged in this order from above.