JPS6339469B2 - - 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, 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 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. There is a problem that makes installation in a room etc. 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 can be quickly supplied to the booster without relying on the air ejector, and negative pressure can be quickly accumulated. The purpose of the present invention is to provide the above-mentioned negative pressure source device with a simple piping structure, and its features include a main body with an air inlet and an air outlet opening on the outer surface, a decompression chamber, and a decompression chamber and an air outlet. A diff user communicating between The vacuum chamber is connected to the negative pressure outlet hole of the negative pressure booster through one upstream negative pressure passage, and the reduced pressure chamber is connected to the negative pressure chamber of the negative pressure booster through one downstream negative pressure passage. The negative pressure outlet hole is connected to a bypass whose inlet is connected to the atmosphere separately from the intake system of the internal combustion engine, and which bypasses the differential user and communicates between the upper and downstream negative pressure passages, and which has a flow resistance smaller than that of the differential user. A first check valve that prevents backflow of negative pressure to the negative pressure outlet side is interposed, and a second check valve that prevents backflow of negative pressure to the negative pressure extraction hole side is interposed in the downstream negative pressure passage. It is located where it is installed.

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 a booster piston with a diaphragm is included in the booster shell 1. 2 defines a negative pressure chamber 3. Further, reference numeral E designates an internal combustion engine of an automobile, and its intake system 4 is composed of an intake manifold 5 and a carburetor 6 mounted at its upstream end, and 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 a single negative pressure passage 9 connects this negative pressure outlet hole 8 and the negative pressure chamber 3 of the booster S. An air ejector 10 is provided in the middle as follows. In the negative pressure passage 9, the part between the negative pressure outlet hole 8 and the air ejector 10 is called an upstream negative pressure passage 9a, and the part 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 main body 11 of the air ejector 10 has an air inlet 12 that opens on the front side and communicates with the atmosphere separately from the engine intake system 4, and an air outlet 13 that opens on the rear side. A suction port 14 that opens on the side surface, a decompression chamber 15 and an exit chamber 16 that are different from each other in the suction port 14 and the air outlet 13, respectively, and a diffuser 17 that communicates between the two chambers 15 and 16 are provided. It is connected to the downstream end of the upstream negative pressure passage 9a, and the suction port 14 is connected to the upstream end of the downstream negative pressure passage 9b. Deaf user 17
is a tapered portion 1 formed on one end surface of the decompression chamber 15.
8, an unwidened tapered part 19 formed on one end surface of the outlet chamber 16, and a throat part 20 connecting both the tapered parts 18 and 19. A nozzle 21 with a spout directed toward the throat portion 20 is disposed close to the tapered portion 18 .

Furthermore, the main body 11 includes a bypass 22 that bypasses the differential user 17 and has a flow path resistance smaller than that of the differential user 17.
A first check valve 23 is provided in this bypass 22.
will be provided. Further, as shown in FIG. 1, a second check valve 24 is provided in the downstream negative pressure passage 9b between the bypass 22 and the negative pressure chamber 3, and both the first and second check valves 23 and 24 are connected to each other. is also configured to prevent negative pressure from flowing backward from the negative pressure chamber 3 side to the negative pressure outlet hole 8 side.

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. In this way, the negative pressure in the negative pressure chamber 3 is first rapidly increased to the level of the suction negative pressure of the engine E.

On the other hand, the negative pressure acting on the outlet chamber 16 acts on the nozzle 21 through the diffuser 17, and with the suction force of this negative pressure, the nozzle 21 sucks in outside air from the air inlet 12 and injects it toward the diffuser 17. Since a high-speed jet of air is generated and the pressure in the vacuum chamber 15 is reduced accordingly, air is sucked through the suction port 14 to further reduce the pressure in the downstream negative pressure passage 9b, that is, increase the negative pressure in the vacuum chamber 3. 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. Note that the air taken in by the nozzle 21 is outside air that is introduced through an air inlet 12 that communicates with the atmosphere separately from the engine intake system 4, and its pressure is always approximately constant. The intake air in the suction system 4 upstream of the throttle valve 7 (this intake air causes pressure fluctuations due to the opening and closing of the throttle valve 7, etc.) is transferred to the nozzle 21.
Compared to something that is inhaled internally, a strong air ejector effect can be stably obtained.

Furthermore, 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 immediately closes accordingly, 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 and an air outlet opening on the outer surface includes a decompression chamber, a diff user communicating between the decompression chamber and the air outlet, and a connection between the air inlet and the diff user in the decompression chamber. An air ejector is constructed by providing a nozzle capable of ejecting air toward the target, and the air outlet is connected to a negative pressure outlet provided in the intake system downstream of the throttle valve of the internal combustion engine through one upstream negative pressure passage. Since the reduced pressure chamber is connected to the negative pressure chamber of the negative pressure booster via one downstream negative pressure passage, the air ejector is actuated by the engine's suction negative pressure and the reduced pressure chamber of the air ejector is connected to the negative pressure chamber of the negative pressure booster. A suction negative pressure that is higher than the suction negative pressure generated by the engine can be applied to the negative pressure chamber of the booster, and the desired boost ratio can be obtained without special expansion of the pressure receiving area of the pressure receiving part of the booster. be able to. 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 first non-return check that prevents negative pressure from flowing back to the negative pressure outlet side is provided in a bypass that bypasses the differential user and communicates between the upper and downstream negative pressure passages and has a flow path resistance smaller than that of the differential user. Since the valve is installed, after the engine starts, the intake negative pressure of the engine is mainly supplied through the bypass, which has a small flow path resistance, until the negative pressure in the negative pressure chamber of the booster reaches the magnitude of the engine intake negative pressure. It is possible to quickly supply the air to the negative pressure chamber of the booster, increase the negative pressure in the negative pressure chamber quickly, establish the operational state of the booster at an early stage, and When the suction negative pressure becomes higher than the engine suction negative pressure, the first check valve is closed to prevent the suction negative pressure of the air ejector from short-circuiting to the bypass and transfer it to the negative pressure chamber of the booster. can be reliably supplied.

Furthermore, since a second check valve is installed in the downstream negative pressure passage to prevent negative pressure from flowing back toward the negative pressure outlet side, when the intake negative pressure of the engine decreases or disappears, the check valve is closed. By closing, it is possible to prevent negative pressure from flowing back from the negative pressure chamber to the negative pressure passage, thereby preventing a decrease in the negative pressure in the negative pressure chamber.

Furthermore, since the air inlet of the air ejector is communicated with the atmosphere separately from the engine's intake system, it is possible to always introduce outside air at a substantially constant pressure (atmospheric pressure) into the air inlet, and the introduced pressure is equal to the intake pressure. It is not affected by pressure fluctuations of intake air within the system, and a strong air ejector effect can be stably obtained.Moreover, since there is no need to connect the air inlet to the intake system, the structure is simplified accordingly.

Furthermore, each of the upper and downstream negative pressure passages is communicated by a bypass that bypasses the differential user, so that the common single upstream negative pressure passage introduces the intake negative pressure in the intake system to the air ejector. It is also used as a passage for introducing the bypass flow that bypasses the diff user of the intake negative pressure into the downstream negative pressure passage via the bypass, and also as a passage for taking out the negative pressure of the suction system connected to these passages. Only one hole needs to be provided, so the overall piping structure of the negative pressure passage becomes simple and short, contributing to cost reduction and improved assemblability.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view showing one embodiment of the device of the present invention, and FIG. 2 is an enlarged vertical sectional side view of the main part of the device, which is an air ejector and its surroundings. 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 with an air inlet 12 and an air outlet 13 opened on the outer surface has a decompression chamber 15 and a decompression chamber 15.
and the air outlet 13.
7, and a nozzle 21 capable of ejecting air from the air inlet 12 toward the diffuser 17 in the decompression chamber 15 to constitute the air ejector 10, and the air outlet 13 is connected to the intake system downstream of the throttle valve 7 of the internal combustion engine E. One upstream negative pressure passage 9a in the negative pressure outlet hole 8 provided in
The decompression chamber 15 is connected to the negative pressure chamber 3 of the negative pressure booster S through one downstream negative pressure passage 9b, and the air inlet 12 is connected to the suction system of the internal combustion engine E. The upper and downstream negative pressure passages 9 communicate with the atmosphere separately from the upper and downstream negative pressure passages 9 and bypass the differential user 17.
A first check valve 23 that prevents negative pressure from flowing back toward the negative pressure outlet 8 side is provided in a bypass 22 that communicates between a and 9b and has a flow path resistance lower than that of the diffuser 17.
A negative pressure booster for a vehicle, comprising a second check valve 24 interposed in the downstream negative pressure passage 9b to prevent backflow of negative pressure toward the negative pressure outlet 8 side. Negative pressure source device.