JPH09112349A - Butterfly throttle valve type carburetor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carburetor to form a fuel system in a single system constitution of which is simplified, perform the stable feed of fuel in a proper air-fuel ratio, and besides the height be low. SOLUTION: A fuel injection nozzle 7 opened to a spot situated downstream from a butterfly throttle valve 5 is communicated with a control pressure chamber 11 through an air-fuel ratio passage 10, and a fuel passage 12 and an air introduction passage 14 are connected to the control pressure chamber 11. The throttle areas of the air-fuel mixture passage and the air introduction passage are set to a value at which a pressure in the control pressure chamber enters a region where air compression is prevented from occurring. By controlling fuel fed from the control pressure chamber by a control valve 23 interlocked with the butterfly throttle valve, air-fuel mixture the air-fuel ratio of which is kept at a constant value is generated in the control pressure chamber. When compressive air-fuel mixture is fed to an intake passage 3 and mixed in air controlled by the butterfly throttle valve, compressive fluids are mixed together in the intake passage and air-fuel mixture fed to an engine is brought into a constant value at a whole rotation area. This constitution forms a fuel system in a single system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a butterfly throttle valve type carburetor for controlling the air-fuel ratio and amount of air-fuel mixture supplied to an engine.

[0002]

2. Description of the Related Art Generally, a carburetor has a small intake flow rate due to the compressibility of air when the negative pressure in the intake pipe is large such as idling, resulting in a rich air-fuel ratio. As described above, when the intake pipe negative pressure becomes small, the air-fuel ratio becomes thin and the fuel becomes insufficient. Therefore, it is necessary to separately provide a fuel control system such as a low speed system and a power system.

[0003]

However, when the carburetor is made multi-system like this, the air-fuel ratio control becomes complicated, and the breathing is caused because the connection of each fuel system does not work well at the time of vehicle start and sudden acceleration. Riding comfort problems such as occurrence will occur.

Further, a jet needle interlocking with the throttle valve is inserted into a needle jet opening in the main intake passage, and the needle jet is pulled up in accordance with the opening operation of the throttle valve, and is formed between the jet portion of the needle jet and the needle. There is a vaporizer that controls the supplied fuel from idling operation to full open operation by changing the area of the gap, but this also controls compressible air with a throttle valve and non-compressible fuel with a jet needle However, the influence of the compressibility cannot be avoided, and it is difficult to make the air-fuel ratio constant in the entire operating range. Further, in the carburetor having the sliding throttle valve, the sliding throttle valve moves in a direction substantially orthogonal to the main intake passage, so that the carburetor becomes taller.

It is an object of the present invention to provide a fuel system having a simple structure and a stable fuel supply with an appropriate air-fuel ratio, and a short carburetor. .

[0006]

[Technical Means for Solving Problems] A butterfly throttle valve for opening and closing the main intake passage to directly control the engine output is provided, and a fuel injection port is opened in the main intake passage downstream of the throttle valve, and the butterfly throttle valve is also provided. No fuel jet is provided upstream. The fuel injection port is communicated with the control pressure chamber by the air-fuel mixture passage, and the fuel passage and the air introduction passage are connected to the control pressure chamber, and the air-fuel mixture is controlled so that the negative pressure in the control pressure chamber becomes a predetermined value or less. Set the throttle area of the passage and the air introduction passage. A control valve is provided in the fuel passage in cooperation with a butterfly throttle valve to adjust the throttle area of the fuel passage and control the amount of fuel injected into the control pressure chamber.

[0007]

According to the above construction, the negative pressure of the control pressure chamber is determined by the throttle area ratio of the air introduction passage and the air-fuel mixture passage, and is controlled to a negative pressure at which the air is not compressed. Further, since the fuel sucked from the fuel passage into the control pressure chamber is controlled by the control valve that works in conjunction with the butterfly throttle valve, if this fuel is controlled in proportion to the amount of air flowing in from the air introduction passage, The air-fuel ratio of the air-fuel mixture generated in the control pressure chamber is always constant.

The air-fuel mixture having a constant air-fuel ratio generated in the control pressure chamber is supplied to the main intake passage through the air-fuel mixture passage and mixed with the air controlled by the butterfly throttle valve. On the other hand, the air-fuel mixture generated in the control pressure chamber is a compressible fluid similar to air because the volume ratio of air is large, and therefore is supplied from the air and fuel injection holes controlled by the butterfly throttle valve. Both air-fuel mixtures become compressible fluids,
As a result, the air amount and the air-fuel mixture amount are proportional in the entire rotation range, and the air-fuel ratio supplied to the engine is always constant.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a vertical sectional view showing an embodiment of the present invention, and FIGS. 2 and 3 are vertical sectional views showing another embodiment of the present invention.

Reference numeral 1 is a butterfly throttle valve type carburetor, and a main intake passage 3 penetrates through a body 2 of the carburetor, and a valve shaft 4 is rotatably provided across the main intake passage 3. A butterfly throttle valve 5 is attached to the valve shaft 4, and the butterfly throttle valve 5 opens and closes the main intake passage 3 by the rotation of the valve shaft 4 to control the engine output. A main intake throttle portion 6 is formed between a peripheral edge of the butterfly throttle valve 5 and an inner wall of the main intake passage 3 facing the peripheral edge of the butterfly throttle valve 5.
The effective aperture of is controlled.

On the other hand, a fuel injection hole 7 is opened in the main intake passage 3 downstream of the butterfly throttle valve 5, and this injection hole 7 is connected to the control pressure chamber 11 by a mixture passage 10. In the control pressure chamber 11, the air introduction passage 14 and the fuel passage 1 are provided.
2 are connected to each other, and the mixture passage 10 and the air introduction passage 14 are connected.
An air-fuel mixture jet 15 and an air jet 16 are provided in each. The air-fuel mixture jet 15 and the air jet 16 do not cause air compression even when the negative pressure in the control pressure chamber 11 becomes highest during idling or deceleration 6
It is set to 0 mmHg or less, and the throttle area of the air jet 16 is set larger than the throttle area of the air-fuel mixture jet 15. The other of the air introduction passages 14 is connected to the atmosphere or to the intake downstream of an air cleaner (not shown),
The lower portion of the fuel passage 12 communicates with the float chamber 18 below the oil level. The fuel in this float chamber 18 is float 2
It is formed on the constant oil surface by a float mechanism constituted by 0 and the needle valve 21. This float mechanism has a general structure which has been conventionally used.

In the fuel passage 12, the control pressure chamber 1
1 is provided with a control valve 23 for controlling the fuel supplied to
The control valve 23 is interlocked with the butterfly throttle valve 5 by a connecting mechanism 25 using a conventionally known link or cam. A main jet 22 is provided below the fuel passage 12 as needed.

FIG. 2 shows another embodiment of the control valve 23. A control needle 27 is inserted into a jet 24 provided in the fuel passage, and the control needle 27 and the butterfly throttle valve 5 are interlocked. I am letting you. Explaining one example thereof, a chamber 30 is provided above the control pressure chamber 11,
A cam 31 is rotatably housed in this chamber 30 and
The control needle 27 is biased toward 1, and the top of the control needle 27 is brought into contact with the cam 31. The cam 31 is provided with a rod 33 protruding to the outside of the carburetor, and the rod 33 and the valve shaft 4 of the butterfly throttle valve 5 are interlocked by a linking mechanism 25 using a conventionally known link or cam or the like. The control needle 27 is configured to advance and retreat into the fuel passage 12 as the throttle valve 5 rotates.

In the above embodiment, as the control valve 23, a rotary valve is shown in FIG. 1 and a needle valve is shown in FIG. 2, but, for example, a butterfly valve and a slide valve can also be used.

Next, the operation of the above embodiment will be described. The negative pressure of the control pressure chamber 11 is determined by the area ratio of the air-fuel mixture jet 15 and the air jet 16, and even when the intake negative pressure downstream of the butterfly throttle valve 5 becomes the highest at the time of idling or deceleration, air compression is performed. It is controlled to 60 mmHg or less, which does not occur. Further, from the fuel passage 12 to the control pressure chamber 1
Since the fuel sucked into 1 is controlled by the control valve 23 which works in conjunction with the butterfly throttle valve 5, the control pressure chamber is controlled by controlling this fuel in proportion to the amount of air flowing from the air introduction passage 14. The air-fuel ratio of the air-fuel mixture generated in 11 is always constant.

The air-fuel mixture having a constant air-fuel ratio generated in the control pressure chamber 11 is supplied to the main intake passage 3 through the air-fuel mixture passage 10 and mixed with the air controlled by the butterfly throttle valve 5. On the other hand, the air-fuel mixture generated in the control pressure chamber 11 has a large volume ratio of air and thus is a compressible fluid similar to air. Therefore, the air and fuel injection holes 7 controlled by the butterfly throttle valve 5 are used. The air-fuel mixture supplied from the both becomes compressible gas, and as a result, the amount of the air mixed in the main intake passage 3 and the amount of the air-fuel mixture are always proportional to each other, and the air-fuel ratio supplied to the engine is in the entire rotation range. It becomes constant at.

FIG. 3 shows an embodiment in which a correction valve 40 capable of adjusting the amount of air is provided in the air introduction passage 14 and the negative pressure of the control pressure chamber 11 is adjusted to correct the mixing ratio A / F. . As the correction valve 40, one that is driven by the output signals of various sensors, one that is manually adjusted, or the like can be used.

[0018]

As described in detail above, according to the present invention, air and fuel are mixed in a control pressure chamber controlled to a negative pressure of a magnitude that does not cause air compression, and an air-fuel mixture with a constant air-fuel ratio is obtained. By mixing this air-fuel mixture with the air metered by the butterfly throttle valve in the main intake passage downstream of the butterfly throttle valve, the air-fuel ratio supplied to the engine can be kept constant over the entire operating range. The system can be controlled by one system, cost can be reduced, and breathing can be prevented when the vehicle starts or suddenly accelerates.

Further, since the above structure is realized by the butterfly throttle valve type carburetor, the carburetor can be made short.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing another embodiment of the present invention.

FIG. 3 is a principal part explanatory view showing an example in which a correction valve is provided in the air introduction passage of the present invention.

[Explanation of symbols]

 1 Butterfly throttle valve type carburetor 3 Main intake passage 5 Butterfly throttle valve 10 Mixture passage 11 Control pressure chamber 12 Fuel passage 14 Air introduction passage 15 Mixture jet 16 Air jet 23 Control valve

Claims (1)

[Claims] 1. A butterfly throttle valve for opening and closing the main intake passage to directly control the engine output. A fuel injection port is opened in the main intake passage downstream of the throttle valve, and moreover, the fuel throttle is provided upstream of the butterfly throttle valve. The fuel injection port is not provided at all, the fuel injection port is communicated with the control pressure chamber by the air-fuel mixture passage, the fuel passage and the air introduction passage are connected to the control pressure chamber, and the negative pressure of the control pressure chamber is equal to or lower than a predetermined value. In the carburetor that sets the throttle areas of the air-fuel mixture passage and the air introduction passage so that the throttle area of the fuel passage is adjusted in cooperation with the butterfly throttle valve in the fuel passage, and the fuel is jetted to the control pressure chamber. A butterfly throttle valve type carburetor comprising a control valve for controlling the fuel amount.