JPS60173359A - Gas mixer for liquefied-petroleum-gas engine - Google Patents

Abstract

PURPOSE:To make an aeration quantity abundant so much in time of high load driving as well as to prevent fuel gas from thickening, by interconnecting a fuel passage to the upstream side of a Venturi tube in a gas feed Venturi of an LPG engine. CONSTITUTION:A hole 8 is installed in an upstream end of a Venturi 2 of a carburetor 1, which mixes gas to be fed out of a vaporizer 6 of an LPG engine into suction air, so as to be interconnected to a hole 4 installed in the narrowest part and a fuel passage 3 inside the Venturi. With this constitution, in time of normal driving, an air quantity from the hole 8 is so little whereby if air-fuel ratio adjustment 5 takes place under this condition in advance, dynamic pressure becomes high when a suction air quantity is abundant enough at high load so that a large quantity of air is led into the inside, thus an air-fuel mixture is prevented from thickening.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mixer for mixing liquefied gas from a vaporizer with intake air when liquefied gas such as LPG is gasified under reduced pressure using a vaporizer and supplied to an engine.

As is well known, an engine that uses liquefied gas such as LPG as fuel is equipped with a pressure-resistant container filled with LPG and a vaporizer that converts it into gas under reduced pressure. The intake negative pressure sends it from the vaporizer to the mixer, where it is mixed with intake air and supplied to the engine. It is desirable that the air-fuel ratio be uniform during low-load operation, that is, in the region where the amount of intake air is small, and during high-load operation, that is, in the region where the amount of intake air is large. As the amount increases, the air-fuel ratio tends to become richer, and the cause of this is the vaporizer.

That is, a vaporizer is equipped with a primary chamber that introduces liquefied gas from a pressure-resistant container and a secondary chamber that sends the liquefied gas that has been gasified under reduced pressure to a mixer. A passage connecting the primary and secondary chambers is opened in conjunction with the movement of the membrane that separates the chambers, and the liquefied gas is sent from the primary chamber to the mixer via the secondary chamber.

The passage is closed by a secondary valve that has a closing spring acting on it, and when the engine is stopped, this secondary valve closes the passage due to the closing spring, but when the engine is started, When the gas pressure in the secondary chamber becomes lower than atmospheric pressure, the membrane moves toward the secondary chamber due to the pressure difference, overcomes the force of the valve closing spring, and opens the secondary valve. let As the intake air amount increases, the venturi negative pressure also increases, and the valve opens wide against the force of the valve closing spring, and as the venturi negative pressure decreases, it acts in the valve closing direction. That is, the valve closing spring is balanced so as to deliver an appropriate amount of liquefied gas in accordance with the amount of intake air.

However, in reality, as the amount of intake air increases, the venturi negative pressure increases in a quadratic curve as shown by the solid line in Figure 3, while the drag force of the valve closing spring increases as shown by the broken line. Changes linearly.

Therefore, in a region where the amount of intake air is large, the drag force of the valve closing spring cannot follow the venturi negative pressure, so the secondary valve is opened more than necessary and a large amount of liquefied gas is sent out to the mixer 5. This causes the air-fuel ratio to become rich during high-load operation, which makes it difficult to take countermeasures and worsens the reduced fuel consumption rate.

The present invention aims to solve these problems in a mixer and equalize the air-fuel ratio, and is characterized by providing a vent hole that communicates the upstream side of the venturi in the intake path with the fuel passage. It is something to do.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a partial vertical cross-sectional view of the mixer of the present invention.

1 is a mixer, 2 is a venturi, 3 is an annular portion surrounding the venturi 2, 4 is a nozzle opening, 5 is a fuel adjustment screw, 6
7 indicates a vaporizer, 7 indicates a fuel passage from the vaporizer 6 to the annular portion 31, and 10 indicates an intake passage. and venturi 2
Ventilation holes 8 communicating with the annular portion 3 are provided at several locations at the upper end of the holder.

The mixer 1 of this embodiment is configured as described above.

When the engine starts, the liquefied gas, that is, the fuel, which is reduced in pressure by the vaporizer S due to the suction negative pressure, is transferred to the vaporizer 6.
The fuel passes through the introduction part 9, is metered by the fuel adjustment screw 5, flows into the annular part 3, is sucked out from the nozzle port 4, and reaches the engine. During low-speed operation, that is, when the amount of intake air is small, less air flows into the annular portion 3 from the vent hole 8, so that it is supplied to the engine without affecting the air-fuel ratio.

As the amount of intake air increases, the amount of fuel sucked out also increases, and the dynamic pressure of the intake air causes a large amount of air to flow into the annular portion 3 through the vent hole 8 provided in the venturi 2, directly thinning the fuel. Overall, the amount of intake air is increased to maintain the same air-fuel ratio as during low-load operation.

In the above embodiment, the vent hole communicating the upstream side of the venturi and the fuel passage 7 was formed at the upper end of the venturi 2.
The invention is not limited to this means. For example, it may be communicated directly with the fuel introduction part 9 using a pipe or the like.

Further, the number and diameter of the vent holes 8 according to the embodiment described above are appropriately selected so as not to affect the engine during low load operation and to provide the fuel flow rate required by the engine during high load operation.

As described above, since the present invention is provided with a vent that communicates the upstream side of the venturi with the fuel passage, it is possible to accommodate the increase in the fuel flow rate due to the quadratic increase in the negative pressure of the venturi during high-load operation. The air from the pores directly thins the fuel, increasing the amount of intake air as a whole, making it possible to maintain the air-fuel ratio during high-load operation to the same air-fuel ratio as during low-load operation. Therefore, good results can be achieved in terms of emission countermeasures, and the fuel consumption rate can also be improved.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which Fig. 1 is a longitudinal cross-sectional partial view, Fig. 2 is an enlarged view of the main part, and Fig. 3 shows the venturi negative pressure against the intake air amount ζ and the drag force of the vaporizer valve closing spring. It is a graph showing the relationship between. 1... Mixer, 2... Venturi, 3... Annular part. 4... Nozzle port, 6... Vaporizer, 7... Fuel passage 8... Vent hole, 9... Introducing part. Death +11←Inhalation to round>/l￥9 people [

Claims (1)

[Claims] A mixer for a liquefied gas engine that is provided with a vent that communicates the upstream side of a venturi in an intake path with a fuel passage.