JPH048864A - Fuel supply device of spark ignition engine - Google Patents

Abstract

PURPOSE:To enable safe driving of an engine, to reduce flue gas and to easily stop one of fuel supply with an air open valve interlocking with a throttle valve by selectively supplying a fuel with excellent ignitionability and a fuel with poor startability according to a driving state of the engine. CONSTITUTION:At start of an engine, while an opening degree of a throttle valve 10 is small, fuel supply from a fuel supply valve 11 is stopped and a fuel with excellent ignitionability such as gasoline is supplied from a carburetor 9 and it is increased as the throttle opening degree becomes larger. In the meantime, when the throttle opening degree reaches a predetermined value, a fuel with poor startability such as light oil, lamp oil or alcohol is supplied from the fuel supply valve 11. In order to rapidly stop fuel supply while driving, an air open valve 19 is opened as the throttle valve 10 is closed, and a nozzle pipe 15 is made to communicate with the outside air through a bypass pipe 18. By this, a negative pressure at a venturi part 17 is eliminated and fuel supply is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel supply system for a spark ignition engine using light oil, kerosene or alcohol fuel.

[Prior Art] Conventionally, spark ignition engines that use fuels with poor startability such as diesel oil, kerosene, or alcohol have poor startability, especially low-temperature startability, so fuels with good ignitability such as gasoline are used for starting. There is a known method in which the engine is started, and once the engine has warmed up sufficiently, the engine is switched from gasoline to the fuel with poor startability. In this case, two carburetors are used, one for fuel with good ignitability and one for fuel with poor startability.

[Problem to be solved by the invention] By the way, in a spark ignition engine that supplies a fuel different from gasoline, there is a problem that if the fuel necessary for the operating condition is supplied all at once before rated operation is reached, the engine will malfunction. There is. However, in the above conventional system, the carburetor supplies fuel with poor startability, so when the engine starts, as the throttle opening increases, fuel is supplied from the float chamber of the carburetor all at once, causing the engine to start. This has led to problems such as poor performance and an increase in smoke emissions.

In addition, after the engine starts, abnormal operation will occur if the gasoline supply is not stopped, but if you want to suddenly stop the fuel supply during operation, install a solenoid valve in the fuel passage that connects the carburetor and the intake pipe. supply must be stopped,
This requires a control power source and requires a change in the design of the carburetor, leading to problems such as Q.

The present invention solves the above-mentioned problems, and aims at stable operation of the engine and reduction of exhaust smoke in spark ignition engines that use fuel with poor startability such as diesel oil, kerosene, or alcohol, and also improves the fuel supply. It is an object of the present invention to provide a fuel supply device for a spark ignition engine that can be easily stopped.

[Means for Solving the Problems] For this purpose, the fuel supply device for a spark ignition engine of the present invention includes a carburetor 9 disposed in the intake pipe 4 of the engine 1.
, a throttle valve 10 and a fuel supply valve are provided, and the carburetor 9 supplies fuel with good ignitability such as ganlin, and the fuel supply valve 11 supplies fuel with poor startability such as light oil, kerosene or alcohol. Furthermore, the carburetor 9 has a nozzle pipe 15 that opens into the intake pipe 4, and an atmosphere release valve 19 that allows the nozzle pipe 15 to be opened to the atmosphere. It is characterized by being interlocked with the valve 10.

Note that the numbers added to the above configurations are for comparison with the drawings to facilitate understanding, and the configurations of the present invention are not limited thereby.

[Function] In the present invention, when the fuel supply is suddenly stopped during operation, the throttle valve 10 closes, and in conjunction with this, the atmosphere release valve 19 opens and the nozzle pipe 15 closes to the bypass pipe 1.
As a result of the communication with the atmosphere via the venturi portion 17, the negative pressure in the venturi portion 17 disappears and the fuel supply is stopped.

[Example code] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a fuel supply system for a spark ignition engine according to the present invention.
FIG. 2 is a configuration diagram showing an example.

The spark ignition engine 1 includes a cylinder 2, a piston 3, an intake pipe 4, an exhaust pipe 5, an intake valve 6, and an exhaust valve 7. An air filter 8, a carburetor 9, a throttle valve 10, and a fuel supply valve 11 are arranged in the intake pipe 4 in this order from the upstream side.

The carburetor 9 consists of a float chamber 12, a float 13, a fuel supply pipe 14, a nozzle pipe 15, and an air bypass pipe 16 for generating a differential pressure. It is opened. Also,
A bypass pipe 18 is branched into the nozzle pipe 15, and an atmosphere release valve 1 is provided at the tip of the bypass pipe 18 to enable release to the atmosphere.
9 is provided. The atmosphere release valve 9 is connected to a throttle lever that operates a throttle valve 10, and when the throttle valve 10 is closed, the atmosphere release valve 1
9 is configured to be open.

A fuel with good ignitability, such as gasoline, is supplied to the float chamber 12 from a fuel pump (not shown) through the fuel supply pipe 14, and is adjusted to a constant amount by the float 13. As the opening degree of the throttle valve 10 increases, the venturi portion 17
As the negative pressure increases, a proportionate amount of gasoline is sprayed from the nozzle pipe 15 into the intake pipe 4. On the other hand, the fuel supply valve 11 receives diesel oil from a fuel pump (not shown).
Fuel with poor starting properties, such as kerosene or alcohol, is supplied.

Next, a method of supplying fuel to the spark ignition engine will be explained with reference to FIG.

When starting the engine, while the opening degree of the throttle valve 10 is small, the fuel supply from the fuel supply valve 11 is stopped, and fuel with good ignitability such as gasoline is supplied from the carburetor 9 as shown in FIG.
As shown by the line, increase as the throttle opening increases. The engine starts and the throttle opening is set to the predetermined value θ
When the fuel supply valve 11 reaches 1, a fuel with poor startability such as diesel oil, kerosene, or alcohol is supplied from the fuel supply valve 11 as shown by line B in the figure, and the supply of gasoline fuel is decreased and eventually stopped. Note that the fuel supply from the fuel supply valve 11 may be increased in stages as shown by line C in the figure.

When the fuel supply is suddenly stopped during operation, the throttle valve 10 closes, and in conjunction with this, the atmosphere release valve 19 opens and the nozzle pipe 15 communicates with the atmosphere via the bypass pipe 18. , the negative pressure in the venturi portion 17 disappears and the fuel supply is stopped.

[Effects of the Invention] As described above, according to the present invention, fuel with good ignitability such as gasoline is supplied from the carburetor, and fuel with poor startability such as diesel oil, kerosene or alcohol is supplied from the fuel supply valve. , stable operation of the engine and reduction of exhaust smoke can be achieved.

In addition, since the gasoline fuel supply is stopped by an atmosphere release valve that is linked to the throttle valve, a control power source is not required compared to stopping the fuel supply by a solenoid valve.
There is no need to change the design of the carburetor.

[Brief explanation of drawings]

FIG. 1 shows a fuel supply method for a spark ignition engine according to the present invention.
FIG. 2 is a diagram showing the configuration of the embodiment and is a diagram for explaining the fuel supply method. 1... Spark ignition engine, 4... Intake pipe, 9...
Carburetor 10...Throttle valve, 11...Fuel injection valve, 15...Nozzle pipe, 19...Atmospheric release valve. Applicant: Tonen Co., Ltd. Representative Patent Attorney Hiroki Shirai (7 others) Throttle opening (Z)

Claims (1)

[Claims] (1) A carburetor installed in the intake pipe of the engine,
A throttle valve and a fuel supply valve are provided, a fuel with good ignitability such as gasoline is supplied from the carburetor, and a fuel with poor startability such as light oil, kerosene or alcohol is supplied from the fuel supply valve, and A spark ignition engine characterized in that the carburetor has a nozzle pipe that opens into the intake pipe and an atmosphere release valve that allows the nozzle pipe to be opened to the atmosphere, and the atmosphere release valve is linked with the throttle valve. fuel supply system.