JPS59231165A - Auxiliary fuel supplying device for carburettor - Google Patents

Abstract

PURPOSE:To supply the auxiliary fuel upon a high load by a method wherein a path is provided at the center of the end of a needle valve provided in a sliding piston type throttle valve to communicate the path with a port opened in a suction path at the opening degree of the valve higher than predetermined. CONSTITUTION:The needle valve 4, provided at the lower end of the throttle valve consisting of a sliding piston 3, is provided with the path 7 at the central part of the lower end thereof. The lower part of the path 7 is opened at the lower end of the needle valve 4 while the upper part thereof is opened at a position 6 whereat the path 7 is opened in a suction air path when the piston 3 has risen to the highest position thereof. According to this method, the port 6 is opened in the suction air path when the piston 3 has risen upon the high load of an engine and the auxiliay fuel may be supplied through the path 7.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an auxiliary fuel supply system for a carburetor used in an engine, which allows auxiliary fuel to be added when the throttle valve is fully opened to obtain maximum output.

In a carburetor, a cylindrical throttle valve is slidably provided so as to intersect with the intake passage, and the throttle valve is slid to control opening and closing of the intake passage. With this type, a needle valve protrudes below the throttle valve, the needle valve is inserted into the main fuel nozzle located below the throttle valve, and the needle valve is inserted and removed as the throttle valve slides. The opening area is adjusted according to the opening area of the intake passage by the throttle valve, so that fuel flows out in accordance with the opening area of the intake passage, that is, the amount of intake air. Recently, the operating speed range of engines has expanded and it has become possible to obtain high output at high speeds, but when obtaining maximum output with the throttle valve fully open, if the fuel is set slightly rich, it is possible to Or, in the middle speed range where the torque troughs, an appropriate air-fuel ratio cannot be obtained, and fuel adjustment using the needle valve alone cannot handle this problem. Furthermore, if a separate fuel supply column is provided to assist this, it will increase ventilation resistance, which is undesirable.

In view of this point, the present invention aims to solve the above problem by providing an auxiliary fuel passage in the needle valve when the throttle valve is fully opened.Hereinafter, an embodiment of the present invention shown in the drawings will be described.

A guide tube 2 is installed above the intake passage 1 that penetrates the carburetor laterally.
A cylindrical throttle valve 3 is slidably inserted into the guide cylinder 2.

Then, the throttle valve 3 is slid up and down to open and close the intake passage 1, thereby adjusting the opening area of the intake passage 1. still,
The figure shows the throttle valve 3 when it is fully open, pulled up to its highest position. A needle valve 4 having a tapered tip is connected to the throttle valve 3 so as to protrude downward. The needle valve 4 is inserted into a main fuel nozzle 5 that opens below the throttle valve 3 on the lower surface of the intake passage 1, and is inserted and removed as the throttle valve 3 slides up and down. By the way, from the lower end of the needle valve 4 to the needle valve 4,
An auxiliary fuel passage 7 is provided which passes through the inside and opens above the main nozzle 5 when the throttle valve 3 is fully opened through the side hole 6.

Therefore, until the throttle valve 3 changes from the closed position to a position close to fully open, the needle valve 4 is also pulled up as the throttle valve 3 is opened, and the opening area of the main nozzle 5 is widened, resulting in an increase in the amount of intake air. The fuel flow rate is adjusted to increase accordingly. During this time, the auxiliary fuel passage 7 of the needle valve 4 is
Since there is a person inside the main nozzle 5, it does not work at all, and the fuel is adjusted only by the gap between the needle valve 4 and the main nozzle 5. At maximum output when the throttle valve 3 is fully opened, the upper end horizontal hole 6 of the auxiliary fuel passage 7 of the needle valve 4 comes out above the main nozzle 5 and the intake passage IK closes and opens.
The fuel also flows out from the auxiliary fuel passage 7 due to the intake air. In this way, when the throttle valve 3 is fully opened, fuel is supplied from the auxiliary fuel passage 7 in addition to the fuel supplied from the main nozzle 5, and the fuel is concentrated, making it possible to obtain high output.

As explained above, the present invention opens and closes the intake passage by inserting and removing the throttle valve into and from the intake passage, as well as protruding a needle valve below the throttle valve, and inserting and removing the needle valve into and from the main fuel nozzle to fuel the intake passage. In devices that adjust the flow rate, when the throttle valve is fully opened, we have provided an auxiliary fuel passage in the needle valve that opens from the lower end of the needle valve through the needle valve to the upper side of the main nozzle. In addition to fuel from the main nozzle, fuel can also be supplied from the auxiliary fuel passage, making the fuel richer and increasing maximum output. When the throttle valve is at an intermediate opening other than fully open, the auxiliary fuel passage enters the main nozzle and does not work, and the needle valve can be set differently when fully opened, making setting easier. Furthermore, since the needle valve originally protrudes into the intake passage, intake resistance does not increase.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, with FIG. 1 being a longitudinal side view and FIG. 2 being an enlarged longitudinal side view of the main parts. 1... Intake passage, 3... Throttle valve, 4...
- Needle valve, 5... Main nozzle, 7... Auxiliary combustion passage. To applicant's agent Kiyoshi Inomata (5) - Line 1

Claims (1)

[Claims] A throttle valve is inserted into and removed from the intake passage to open and close the intake passage, and a needle valve protrudes below the throttle valve, and the needle valve is inserted into and removed from the main fuel nozzle to adjust the fuel flow rate. An auxiliary fuel supply device for a carburetor, characterized in that, when the valve is fully opened, the needle valve is provided with an auxiliary fuel passage that opens from the lower end of the needle valve through the inside of the needle valve to the upper side of the main nozzle.