JPS59200046A - Control device for carburetor in supercharged engine - Google Patents

Abstract

PURPOSE:To make the pressure inside a float chamber stable as well as to stabilize the injection of fuel, by interconnecting the inside of a carburetor float chamber of a supercharged engine to a surge tank. CONSTITUTION:Air passing through a supercharger and being pressurized stabilizes a pressure variation inside a surge tank 9, then enters a carburetor 8, forming an air-fuel mixture, and is fed to an engine. With the air chamber portion at the upper part of the float chamber 15 of the carburetor 8 and the surge tank 9 interconnected each other, the supercharging pressure is given inside the float chamber whereby not only fuel supply commensurate to the supercharging pressure is achieved but also a variation in the supercharging pressure is absorbed at the inside of the surge tank and stabilized, so that the internal pressure in the float chamber taking in the supercharging pressure is also stabilized, thus the injection of fuel becomes stable enough.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a supercharger and a control device for a carburetor in a supercharged internal combustion engine in which a carburetor is interposed in an intake path downstream of the supercharger.

Generally, the carburetor of this type of engine is designed to encourage fuel to be ejected from the fuel nozzle (the outlet pressure of the supercharger is applied to the float chamber, but the outlet pressure is controlled by the intake pulsation that occurs in the intake passage). The pressure inside the engine compartment is unstable, and as a result, it becomes difficult to accurately control the amount of fuel jetted from the fuel nozzle depending on the engine operating status, causing fluctuations in the air-fuel ratio of the air-fuel mixture. There is a drawback that it causes

It is an object of the present invention to provide the above-mentioned control device that eliminates such drawbacks. In the internal combustion engine, a surge tank is interposed in an intake passage between the carburetor and the supercharger, and a float chamber of the carburetor is communicated with the surge tank via a pressure introduction passage, and a second A feature of the invention, in addition to the features of the first invention, is that an expansion chamber is provided in the middle of the pressure introduction passage.

Embodiments of the present invention will now be described with reference to the drawings. First, in FIG.
, 5 in the cylinder head 1, and intake and exhaust passages 6 and 7 are connected to these intake and exhaust ports 4 and 5, respectively.

The intake passage 6 is provided with a variable venturi carburetor 8, a surge tank 9, a positive displacement supercharger 1o consisting of a vane pump, and an air cleaner 11 in this order from the downstream side, that is, from the intake boat 4 side. A throttle 6a is formed at the inlet of the surge tank 9 to cooperate with the surge tank 9 to attenuate supply air pulsations caused by the operation of the supercharger 10.

As shown in FIG. 2, the vaporizer 8' includes a venturi section 12. A throttle valve 13 is provided on the downstream side of the intake passage 12, and a choke valve 14 is provided on the upstream side of the intake passage 12, and a float chamber 15 is provided directly below the intake passage 12.
The fuel nozzle 16 that opens into 2 cl is a fuel jet 17.
It communicates with the surface of the fuel oil in the float chamber 15 through. A piston valve 18 protrudes into the venturi portion 12 Q from above so as to be able to rise and fall freely, and a needle valve 19 integrally attached to the lower end of the piston valve 18 adjusts its effective opening area within the fuel nozzle 16. be inserted as shown. The piston valve 18 has a pressure receiving part 18α at the upper end, and this pressure receiving part 1
8. A venturi pressure chamber 20 and an upstream pressure chamber 21 are provided at the upper and lower portions of z, respectively, and the venturi pressure chamber 2o has a return spring 22 that urges the piston valve 18 downward.
The upstream pressure chamber 21 communicates with the upstream side of the intake passage 12 through a through hole 24.

Therefore, when the intake air amount of the engine E increases beyond the value, the pressure in the venturi section 12α that decreases accordingly is introduced into the venturi pressure chamber 20, and a pressure difference is created between the venturi pressure chamber 20 and the upstream pressure chamber 21. The piston valve 18 is pulled up to the point where the pulling force of the pressure receiving part 18α due to the pressure difference and the pushing down force of the return spring 22 are balanced, and the venturi part 12a is pulled up.

The opening degree is increased. Then, the pressure in the venturi section 12.alpha. tries to return to its original value, so that the pressure in the venturi section 12.alpha.
The Z pressure is controlled to be constant after the engine intake air amount exceeds a certain value. The fuel in the float chamber 15 is injected from the fuel nozzle 16 to the venturi section 12ff according to the difference between the pressure in the venturi section 12a and the pressure in the float chamber 15 controlled in this way and the opening area of the fuel nozzle 16. .

Therefore, in order to apply stable pressure to the float chamber 15, the upper space of the float chamber 15 is communicated with the surge tank 9 via the pressure introduction passage 25.

Referring again to FIG. 1, the supercharger 10 is driven from the output of the engine E via a suitable transmission (not shown), and a bypass 2 bypassing the supercharger 10 is provided.
6 is connected to the intake path 6.

This bypass 26 has an on-off valve 2 that can open and close it in a timely manner.
7 is provided.

Next, the operation of this embodiment will be explained. When the engine E is operated, the supercharger 10 is driven by the output of the engine E. The on-off valve 27 is closed while the supercharger 10 is operating to bypass the bypass 2.
6 is closed, the air purified in the air cleaner 11 is pressurized by the supercharger 10, and the surge tank 9 is
is sent to the carburetor 8 through the fuel nozzle 16 and mixed with the fuel jetted from the fuel nozzle 16 to create an air-fuel mixture.
The flow rate is controlled by the air intake port 4, and the air is fed under pressure to the combustion chamber of the engine E. In this way, the charging efficiency of the engine E can be improved, and its output can be increased.

During operation of the engine E, intake pulsation occurs in the intake passage 6 due to the opening/closing action of the intake valve 2 and the intermittent supercharging action of the positive displacement supercharger 10. Pulsations are absorbed by the surge tank 9. Therefore, the pressure inside the surge tank 9 is stably maintained at the average value of the outlet pressure of the supercharger 10, and this pressure is passed through the pressure introduction path 25 to the float chamber 15.
Since the fuel is introduced into the float chamber 15 at a stable pressure state, the fuel can be stably ejected from the fuel nozzle 16.

If the on-off valve 27 is opened while the engine E is running, the bypass 26
is in a conductive state and short-circuits between the outlet and the outlet of the supercharger 10, so the air that has passed through the air cleaner 11 is diverted to the bypass 26.
The supercharger 10 only idles and stops its supercharging action. Such non-supercharging control is performed, for example, when the engine is idling, when the load is low, when the engine is decelerating, etc.

FIG. 3 shows a second embodiment of the present invention, in which an expansion chamber 28 is provided in the middle of a pressure introduction passage 25 that communicates between the float chamber 15 and the surge tank 9, and the other configuration is the same as that of the previous embodiment. This is the same, and in FIG. 3, parts corresponding to those in the previous embodiment are given the same reference numerals.

According to this second embodiment, residual pulsation of the pressure transmitted from the surge tank 9 to the float chamber 15 is further absorbed by the expansion chamber 28 in the middle of the pressure introduction passage 25, making the pressure in the float chamber 15 more stable. can be made into something.

As described above, according to the first invention, a surge tank is interposed in the air supply path between the carburetor and the supercharger, and the float chamber of the carburetor is communicated with the surge tank via the pressure introduction path. Therefore, the pressure in the surge tank, which is less affected by intake pulsation and is always relatively stable, can be applied to the float chamber to stabilize the pressure in the chamber. Therefore, the fuel injection can be controlled accurately according to the operating condition of the engine. It is possible to stabilize the air-fuel ratio of the air-fuel mixture.

Further, according to the second invention, since the expansion chamber is provided in the middle of the pressure introduction passage, the residual pulsation of the pressure transmitted from the surge tank to the float chamber can be absorbed by the expansion chamber, thereby further stabilizing the pressure in the float chamber. Therefore, the air-fuel mixture air-fuel ratio can be further stabilized.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional side view of a supercharged internal combustion engine showing a first embodiment of the present invention, FIG. 2 is an enlarged longitudinal sectional side view of main parts of a carburetor and a surge tank, and FIG. 3 is a drawing similar to FIG. 2, showing a second embodiment; FIG. E... Internal combustion engine 6... Intake path, 8... Carburetor, 9... Surge tank, 10... Supercharger, 15... Float chamber, 25...
...Pressure introduction passage, 28...Expansion chamber Patent applicant Honda Motor Co., Ltd.

Claims (2)

[Claims] (1) In a supercharged internal combustion engine in which a carburetor is installed in the intake passage downstream of the supercharger, a surge tank is installed in the intake passage between the carburetor and the supercharger, and the surge tank A control device for a carburetor in an internal combustion engine with a supercharger, wherein the float chamber of the carburetor is communicated with the float chamber of the carburetor through a pressure introduction passage. (2) In a supercharged internal combustion engine in which a carburetor is interposed in the intake passage downstream of the supercharger, a surge tank is interposed in the intake passage between the carburetor and the supercharger, and the surge tank A control device for a carburetor in an internal combustion engine with a supercharger, the control device communicating with a float chamber of the carburetor via a pressure introduction passage and providing an expansion chamber in the middle of the pressure introduction passage.