JPH0216050Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a device that supplies liquefied gas such as LPG to an engine as a driving fuel.

In a device that uses a vaporizer to gasify high-pressure liquefied gas in a pressure-resistant container under reduced pressure and sends it to a mixer, mixing air and fuel gas and supplying the mixture to the engine, the fuel gas is sent from the vaporizer to the mixer even when the engine is decelerating. Especially in a mixer equipped with a low-speed system, a large amount of fuel gas is sent out due to the high negative pressure in the suction pipe, resulting in a problem of deteriorating fuel efficiency. The present invention has been made for the purpose of providing a liquefied gas supply device for an engine that solves the above-mentioned problems by closing the fuel gas passage only during deceleration, and furthermore, can smoothly return to normal operation. In a liquefied gas supply device for an engine, which includes a vaporizer that gasifies liquefied gas under reduced pressure and a mixer that mixes air and fuel gas, a nozzle port for delivering fuel gas from the secondary chamber of the vaporizer to the mixer. A negative pressure-driven on-off valve is provided in the fuel gas passage leading to the nozzle, and this on-off valve has a communication path that sends a small amount of fuel gas toward the nozzle port when the valve is closed, and the driving portion of the on-off valve is electromagnetically driven. The on-off valve is characterized by being configured so that the on-off valve is closed by the suction pipe negative pressure introduced only when the engine is decelerating.

Next, a specific example of the present invention will be explained according to the drawings. In FIGS. 1 and 2, high-pressure liquefied gas in a pressure-resistant container 1 is gasified under reduced pressure in a vaporizer 2, and then passed through a fuel gas passage 4 to a bench lily 6 of a mixer 5. The air is sent to an intake passage 8 through a slit-shaped nozzle opening 7, mixed with air, and supplied to the engine via an intake pipe 9. The fuel gas passage 4 consists of an external passage 11 extending from the secondary chamber 3 of the vaporizer 2 to the connector 10 at the inlet of the mixer 5, and an internal passage 12 extending from the connector 10 to the nozzle port 7. An on-off valve 15 consisting of a valve body 14 is provided to sit on the seat surface on the downstream side, and the base end of a valve rod 16 passing through the valve seat 13 is fixed to the center of a diaphragm 18 of a drive section 17. The drive section 17 includes the diaphragm 18, a negative pressure chamber 19, and a spring 20, and the elasticity of the spring 20 built into the negative pressure chamber 19 separates the valve element 14 from the valve seat 13.

Negative pressure passage 2 connecting suction pipe 9 and negative pressure chamber 19
1 is provided with an electromagnetically driven control valve 22, which selectively introduces the suction pipe negative pressure and the atmosphere into the negative pressure chamber 19.
That is, when deceleration operation is detected based on the engine speed, throttle valve opening, suction pipe pressure, etc., the negative pressure chamber 19 is communicated with the suction pipe 9, and otherwise the negative pressure chamber 1 is connected to the suction pipe 9.
The control valve 22 is electrically operated to communicate the air outlet 9 with the atmosphere.

FIG. 3 shows a state during deceleration, in which the diaphragm 18 of the drive section 17 is moved into the negative pressure chamber 19 by the suction pipe negative pressure.
The valve body 14 at the tip of the valve stem 16 seats on the valve seat 13 and closes the internal passage 12.

The valve body 14 is provided with a small diameter communication passage 23,
When the valve is closed, fuel gas is sent toward the nozzle port 7 little by little, thereby preventing engine troubles such as car knocking due to lack of fuel gas when normal operation is resumed after deceleration operation.

Note that the on-off valve 15 may be provided in the external passage 11. Further, the communication passage 23 of the on-off valve 15 may be formed by cutting out a part of the valve seat 13, particularly the seat surface.

As described above, according to the present invention, only when the engine is decelerating, the intake pipe negative pressure is used to properly close the on-off valve and close the fuel gas passage, allowing fuel gas to be sucked out from the nozzle port into the intake passage. This prevents fuel gas from being supplied to the engine in large quantities during deceleration when fuel is not required, improving fuel economy.Furthermore, when the valve is closed, fuel gas passes through the opening/closing valve little by little, so that deceleration operation ends. This prevents engine troubles caused by interruptions in fuel gas and enables a smooth return to normal operation.

[Brief explanation of the drawing]

FIG. 1 is a partially cut-away front view showing a specific example of the present invention, FIG. 2 is an enlarged partial vertical cross-sectional view, and FIG. 3 is a partial vertical cross-sectional view of the valve in the closed state. 2... Vaporizer, 3... Secondary chamber, 4... Fuel gas passage, 5... Mixer, 7... Nozzle port, 9
... Suction pipe, 13 ... Valve seat, 14 ... Valve body, 15
...Opening/closing valve, 17...Driving section, 18...Diaphragm, 19...Negative pressure chamber, 20...Spring, 21...
Negative pressure passage, 22...control valve, 23...communication passage.

Claims (1)

[Scope of utility model registration request] In a liquefied gas supply system for an engine that is equipped with a vaporizer that gasifies liquefied gas under reduced pressure and a mixer that mixes air and fuel gas, the fuel gas that flows from the secondary chamber of the vaporizer to the nozzle port for delivering fuel gas of the mixer. A negative pressure-driven on-off valve is installed in the passage,
This on-off valve has a communication path that sends a small amount of fuel gas toward the nozzle port when the valve is closed, and the driving part of the on-off valve is an electromagnetically driven on-off valve that generates suction pipe negative pressure that is introduced only when the engine is decelerating. A liquefied gas supply device for an engine, characterized in that the on-off valve is configured to be closed by the following steps.