JPS6240539B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dual-purpose carburetor that can supply LPG and gasoline to an engine with a single carburetor.

LPG is cheaper than gasoline, so LPG is often used as fuel for car engines in areas where it is available in abundance, but LPG filled in pressure vessels
When the vehicle runs out of fuel, gasoline is used as an alternative fuel to drive to a refueling location. Such a dual-purpose carburetor is usually constructed by replacing the air horn with a choke valve of a normal gasoline carburetor with a bench lily equipped with an LPG nozzle, and the float is connected to the gasoline tank and fuel pump. A valve is installed in the gasoline passage leading to the chamber, which is normally closed to use LPG and opened when necessary to supply gasoline.

By the way, if an internal ventilation system is adopted for the float chamber in a dual-purpose carburetor in which an LPG vent lily and a gasoline vent lily are arranged in series from upstream to downstream, problems may arise in the air-fuel ratio and torque depending on the location of the vent. In other words, if the vent opens downstream of the LPG bench lily and communicates the float chamber with the inside of the carburetor, the LPG vent lily acts as air resistance and reduces the negative pressure in the float chamber as the engine speed increases. This causes an imbalance in the pressure difference between the gasoline oil level and the main nozzle, reducing the amount of gasoline sucked out.
As a result of the test, it was found that as the fuel consumption fell below the required value, as shown in Figure _B1 , the air-fuel ratio became leaner, and as a result, the torque became unstable, as shown in Figure _B2 . In addition, if the vent is opened upstream of the LPG bench lily, it forms a dynamic pressure vent in contrast to the static pressure vent mentioned above, and is not affected by the LPG vent lily and increases as the engine speed increases. Although negative pressure is generated in the float chamber, the increase in fuel consumption is shown in Figure 3 C ₁
The results of the same test revealed that the air-fuel ratio was quite large, and the torque was low as shown in C ₂ in the same figure.

The present invention solves the above-mentioned problems by communicating the float chamber with the inside of the vaporizer both upstream and downstream of the LPG bench lily.

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 denotes a main body provided with a bench lily 3 having a gasoline main nozzle 2, a float chamber 4, a fuel passage, a bleed air port, etc. (not shown);
7 is a flange equipped with a throttle valve 6 and a low-speed port (not shown), and 7 is a bench lily having an LPG nozzle 8; It flows downward and is mixed with LPG or gasoline and supplied to the engine. Gasoline is supplied from a gasoline tank (not shown) through a fuel passage having a fuel pump to the float chamber 4 via a float valve, but when LPG is used, the valve provided in the fuel passage is closed. LPG is supplied from a pressure vessel (not shown) to the bench lily 7 after being depressurized by a vaporizer.

A ventilation hole 11 formed by a restriction 10 on the upstream side of the bench lily 7 and a ventilation hole 13 formed by a restriction 12 on the downstream side of the bench lily are connected to the float chamber 4 by a ventilation path 14.
The apertures 10 and 12 are connected to the upper part of the vent 1.
1 and 13 with different diameters.

As shown in FIG. 2, the bench lily 7 can be replaced with an air horn 16 having a chiyoke valve 15, and is compatible with a gasoline-only carburetor. 17, and has a structure in which both the upstream side and the downstream side of the check valve 15 are communicated with the float chamber 4. However, there are cases in which a dual-use carburetor is manufactured without such compatibility, and the ventilation passages 14 are formed into completely separate passages without merging in the middle, and the diameters of these passages are appropriately selected to improve the throttling effect. The same is true if you add .

According to the present invention configured as described above, when LPG is used, it is sucked out from the nozzle 8 of the bench lily 7 and mixed with air, thereby exhibiting exactly the same function as a conventional mixer. When gasoline is used, even if the LPG bench lily 7 placed upstream of the bench lily 3 acts as air resistance and generates a pressure difference between upstream and downstream, the internal ventilation system allows the float chamber 4 to Since the air passage 14 that communicates with the inside of the vaporizer is opened both upstream and downstream, the pressure on the upstream side and the pressure on the downstream side act on the float chamber 4. Therefore, when the engine speed increases, a pressure intermediate between the upstream pressure and the downstream pressure acts on the float chamber 4.
The pressure difference between the gasoline oil level and the main nozzle 2 can be adjusted according to the engine speed by appropriately selecting the diameter of each vent 11, 13 or the passage diameter of the vent passage 14, as well as the position of the vent 11, 13. By maintaining the fuel consumption properly and keeping the fuel consumption within the range shown in Figure 3 A ₁ , supplying the engine with a mixture with an appropriate air-fuel ratio, Figure 3 A ₂
It is capable of providing stable torque such as.

Furthermore, Figure 3 shows the results of the full load performance test.
For comparison, B ₁ , B ₂ and C ₁ , C ₂ have a vent diameter of 4 mm, and A ₁ and A ₂ of the present invention have a vent diameter of 2.1 mm on the upstream side.
mm, and a vent hole diameter of 4 mm was used on the downstream side.

[Brief explanation of the drawing]

Fig. 1 is a vertical sectional view showing an embodiment of the present invention, Fig. 2
The figure is a vertical cross-sectional partial view explaining compatibility with a gasoline-only carburetor, and FIG. 3 is a characteristic curve diagram. 1... Main body, 2... Main nozzle, 3... Bench lily, 4... Float chamber, 5... Flange, 7... Bench lily, 8... Spout, 10... Throttle, 11... Ventilation port, 12... ...Aperture, 13...Vent, 14...
Ventilation path, 16... air horn.

Claims (1)

[Claims] 1 On the upstream side of the air flow sucked into the engine
A bench lily 7 having a nozzle 8 for LPG is provided, and a bench lily 2 having a main nozzle 3 for gasoline is provided on the downstream side. Gasoline, characterized in that it communicates with the inside of the carburetor through an air passage 14 having 13.
LPG dual-use vaporizer.