JPH0660605B2 - After-fire prevention device for LPG fueled engine vehicles - Google Patents

Description

TECHNICAL FIELD The present invention relates to an engine vehicle using LPG (liquefied petroleum gas) as a fuel, and in particular, LPG fuel is supplied to the engine to cause combustion even after the engine is stopped. The present invention relates to a device for preventing a phenomenon, so-called after-fire.

[Prior Art] FIG. 2 schematically shows a fuel supply system for an engine vehicle using LPG fuel according to the prior art.
As shown in the drawing, when the key switch 1 is turned on and the solenoid valve 2 is opened, the liquid L from the LPG cylinder 3 is discharged.
PG fuel enters the regulator 5 through the filter 4,
The regulator 5 is configured to be depressurized and vaporized, and then absorbed into the engine 7 through the carburetor 6.

More specifically, when a starter motor (not shown) is rotated to start the engine 7, the inside of the intake manifold 8 of the engine 7 becomes negative pressure, and this negative pressure of the manifold is supplied to the regulator 5 via the vacuum hose 9. It is guided to the vacuum chamber, and as a result, a valve (not shown) provided in the slow fuel passage 10 is opened. In this way, the LPG fuel is fed into the slow fuel passage 10
Flow to the carburetor 6 to get the first explosion in the engine 7, and by further increasing the Venturi negative pressure of the carburetor 6, the main fuel passage 11 is also opened and a large amount of LPG fuel is supplied to the engine 7 to complete the explosion. It has become.

Conversely, when the key switch 1 is turned off to stop the engine 7, the solenoid valve 2 is closed and the LPG fuel supply path from the LPG cylinder 3 is shut off. Further, since the main fuel passage 11 is closed because the venturi negative pressure is eliminated, and the manifold negative pressure is zero, that is, the vacuum chamber is at atmospheric pressure, the valve in the slow fuel passage 10 is closed and the LPG fuel for the engine 7 is closed. Does not flow.

[Problems to be Solved by the Invention] However, since the manifold negative pressure generally remains immediately after the engine is stopped, in the above-described conventional technique, the valve of the slow fuel passage remains open and the regulator is closed. There is a problem that the LPG fuel remaining inside may be supplied to the engine through the slow fuel passage and cause afterfire.

It is an object of the present invention to provide an extremely effective means for promptly eliminating such problems.

[Means for Solving the Problems] The after-fire prevention device according to the present invention is a regulator configured to supply LPG fuel to the engine only when the vacuum chamber communicating with the intake manifold of the engine becomes negative pressure. In an engine vehicle using LPG fuel equipped with, the intake manifold and the vacuum chamber are connected so that the intake manifold communicates with the vacuum chamber when the key switch is turned on and the vacuum chamber is opened to the atmosphere when the key switch is turned off. It is characterized in that a three-way switching solenoid valve is provided between the chamber and the chamber.

[Operation] In the after-fire prevention device according to the present invention described above, since the vacuum chamber becomes atmospheric pressure after the key switch is turned off, the LPG from the regulator to the engine is reduced.
The fuel supply path is cut off to prevent afterfire from occurring.

[Embodiment] A preferred embodiment of an afterfire prevention device in an LPG fueled engine vehicle according to the present invention will be described in detail below with reference to the drawings.

The same or corresponding parts as those of the conventional configuration will be described using the same reference numerals.

As shown in FIG. 1, the fuel supply device for an LPG fueled engine vehicle to which the after-fire prevention device according to the present invention is applied has an LPG cylinder 3,
The filter 4, the regulator 5, and the carburetor 6 are mainly included. A three-way switching solenoid valve 20 is provided in a vacuum home 9 that connects the vacuum chamber of the regulator 5 and the intake manifold 8 of the engine 7. This three-way switching solenoid valve 20 includes a solenoid coil 2
When 1 is excited, the vacuum chamber and the intake manifold 8 are communicated with each other, and when the solenoid coil 21 is in the non-excited state, the vacuum chamber is opened to the atmosphere through the air filter 22. Has become. The solenoid coil 21 is configured to be excited when the key switch 1 is turned on.

The operation of the after-fire prevention device according to the present invention having such a structure will be described. When the key switch 1 is turned on to operate the engine 7, the solenoid valve 2 is opened and the LPG fuel is supplied to the LPG cylinder 3.
To the regulator 5, and the solenoid coil 21 of the three-way switching solenoid valve 20 is excited to communicate between the vacuum chamber and the intake manifold 8. As a result, the manifold negative pressure is introduced into the vacuum chamber, the LPG fuel supply device operates exactly as in the conventional configuration, and the LPG fuel is supplied to the engine 7.

When the key switch 1 is turned off to stop the engine 7, the regulator 5 and the LPG cylinder 3 are operated by the solenoid valve 2.
Is cut off. At the same time, the position of the three-way switching solenoid valve 20 is switched, and atmospheric pressure is introduced into the vacuum chamber. As a result, the slow fuel passage 10 is shut off by the valve provided on the way regardless of whether the manifold negative pressure remains. Therefore, after the key switch 1 is turned off and the engine 7 is stopped, the LPG fuel is not supplied to the engine 7, and after-fire does not occur.

EFFECTS OF THE INVENTION Since the after-fire prevention device in the LPG-fueled engine vehicle according to the present invention has the above-described configuration and operation, it is possible to completely prevent after-fire from occurring after the engine is stopped. It has the effect of protecting the engine and extending its life.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing a fuel supply device provided with an afterfire prevention device of the present invention, and FIG. 2 is a schematic explanatory view showing a conventional fuel supply device. In the figure, 1: key switch, 3: LPG cylinder, 5: regulator, 7: engine, 8: intake manifold, 9: vacuum hose, 10: slow fuel passage, 11: main fuel passage, 20: three-way switching solenoid valve ,

Claims (1)

[Claims] 1. A LPG fueled engine vehicle having a regulator configured to supply LPG fuel to the engine only when the vacuum chamber communicating with the intake manifold of the engine has a negative pressure. Three directions between the intake manifold and the vacuum chamber so that the intake manifold and the vacuum chamber are communicated when the switch is turned on and the vacuum chamber is opened to the atmosphere when the key switch is turned off. An after-fire prevention device for LPG-fueled engine vehicles equipped with a switching solenoid valve.