JPH05256212A - Gas fuel supply device for engine - Google Patents

Abstract

PURPOSE:To secure certainty for starting at a low temperature and stability of warming-up operation by supplying air-mixture increased in response to a temperature, to an engine. CONSTITUTION:An opening/closing valve 9 is arranged in a bypass passage 8 for supplying increased air-mixture formed by connecting the upstream side of a throttle valve 7 to the downstream side of the opening/closing valve 9 is driven so that a valve opening is set large at the time of a low temperature and it is gradually made small in response to rise of the temperature by means of fluid substance 10 which expands and contracts according to the temperature of cooling water in an engine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gaseous fuel supply system having a function of smoothly performing a cold start and a warm-up operation of an engine.

[0002]

2. Description of the Related Art A device for supplying gaseous fuel, generally LPG, that is, a mixer installed in an intake system for mixing LPG and air has a nozzle for delivering LPG to an intake passage and a throttle for controlling engine output. In addition to the valve, a bypass passage for adjusting the idle speed is provided by connecting the upstream side and the downstream side of the throttle valve (see Japanese Utility Model Publication No. 57-57252).

In such a gaseous fuel supply device, when the engine is started and warmed up at a low temperature, an automatic choke device of a carburetor for a gasoline engine and a low temperature injection valve of a fuel injection device are not provided. The air-fuel mixture is increased by allowing the driver to manually open the valve to open it. Therefore, it is impossible to avoid the opening difference due to the individual difference of the driver and the early closing of the valve due to the illusion, and it is easy to cause inconvenience such as stop due to a poor starting or an irregular rotation.

On the other hand, a technique for providing an engine with an increased air-fuel mixture by providing an electromagnetic valve in the bypass passage to connect the upstream side and the downstream side of the throttle valve at low temperature is disclosed in Japanese Utility Model Publication No. 54-87320. Since this type has a structure in which the solenoid valve is opened below the set temperature and closed above the set temperature, the supply amount of the air-fuel mixture suddenly changes at the set temperature, and the rotation is likely to malfunction or stop.

[0005]

SUMMARY OF THE INVENTION The problem to be solved by the present invention is to provide an appropriate amount of the increased air-fuel mixture according to the temperature at a low temperature in the conventional gas fuel supply device to surely perform the cold start. At the same time, it was difficult to make the warm-up operation stable.

[0006]

In order to solve the above-mentioned problems, the present invention installs an opening / closing valve in a bypass passage for supplying an increased mixture, which is provided by connecting an upstream side and a downstream side of a throttle valve in an intake passage. Then, the on-off valve is driven by a fluid substance that expands and contracts according to the engine temperature, thereby achieving the purpose of supplying an appropriate amount of the increased air-fuel mixture according to the temperature when the temperature is low.

[0007]

When the engine temperature is low, the fluid substance is contracted and the on-off valve is fully opened, so that a large amount of the increased air-fuel mixture is supplied by the bypass passage. When the fluid substance expands with the rise in temperature and the on-off valve is gradually closed, the increased air-fuel mixture gradually decreases, and when the warm-up is completed, the air-fuel mixture is completely closed and the supply of the air-fuel mixture increase is stopped.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An example in which the present invention is applied to a bypass passage provided on the side of a throttle valve of an LPG mixer will be described with reference to the drawings.
The LPG depressurized and vaporized by a vaporizer (not shown) passes through the supply passage 4 and enters the annular chamber 5 surrounding the venturi 3 provided in the intake passage 2 of the body 1, and then from the nozzle 6 to the venturi 3
Is sent to the narrowest part of the engine and mixed with air to be supplied to an engine (not shown).

A bypass passage 8 is provided downstream of the venturi 3 in the intake passage 2 and connecting the upstream side of the throttle valve 7 and the downstream side of the throttle valve 7, and a piston that crosses the bypass passage 8 is provided. The open-close valve 9 is fitted and supported on the body 1 so as to be linearly reciprocally movable.

On the other hand, the fluid substance 10 which expands and contracts depending on the temperature is generally thermowax, and cooperates with the return spring 14 to the piston 13 through the elastic cover 12 which is filled in the casing 11 and covers the open end thereof. The casing 11 is immersed in the engine cooling water 15.

In the embodiment shown in FIG. 1, the opening / closing valve 9 is directly connected to the tip of the piston 13, and in the embodiment shown in FIG. 2, both ends of the rocking lever 16 are provided at the tip of the piston 13 and the base end of the opening / closing valve 9. The fluid material 10 is rotatably engaged and expands and contracts the fluid substance 10 to be transmitted to the on-off valve 9.

When the temperature of the engine cooling water 15 is low, the fluid material 10 is contracted and the piston 13 is retracted by the spring force of the return spring 14, so that the on-off valve 9 is fully opened and a large amount of increase is made from the bypass passage 8. The mixture is supplied to the engine. When the temperature rises and the fluid substance 10 expands to move the piston 13 forward, the on-off valve 9 gradually closes to gradually reduce the supply amount of the increased air-fuel mixture, and when the warm-up is completed, the on-off valve 9 is closed and bypassed. The passage 8 is closed.

In the above embodiment, the bypass passage 8 is provided in the LPG mixture, but the same is true when the bypass passage is provided in the throttle body which is separate from the body 1. Needless to say.

[0014]

According to the present invention, the on-off valve provided in the bypass passage of the throttle valve is driven by the fluid material that expands and contracts according to the temperature. Supply a proper amount of air-fuel mixture according to the temperature to the engine without causing a shortage or sudden change in the air-fuel mixture flow rate by fixing the open / close valve to the fully open / fully closed position to ensure a low temperature start. In addition to being able to perform the warm-up operation, the warm-up operation can be stably performed.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view showing an embodiment of the present invention.

FIG. 2 is a schematic vertical sectional view showing a different embodiment of the present invention.

[Explanation of symbols] 2 Intake passage 7 Throttle valve 8 Bypass passage 9 Open / close valve 10 Flowing substance

Claims (1)

[Claims] 1. A gas fuel supply system for an engine, wherein an intake passage is provided with a bypass passage for connecting an upstream side and a downstream side of a throttle valve for supplying an increased mixture, and a flow that expands and contracts in accordance with an engine temperature. A gaseous fuel supply system for an engine, wherein an on-off valve driven by a substance is installed in the bypass passage.