JPS6224782Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a needle valve that replenishes fuel in response to a drop in the oil level in a float chamber in a carburetor of an internal combustion engine, especially when the fuel discharge pressure of the fuel pump is high. This invention relates to a device that prevents the spilling phenomenon caused by fuel being vigorously blown out from a needle valve into a float chamber.

[Conventional technology]

Conventionally, in this type of needle valve, a needle valve holder having a small-diameter fuel inlet has a circular cross section, and a valve body, which is inserted into the holder and opens and closes the inlet by float buoyancy, has a square or triangular cross section. A fuel flow passage is provided vertically through the gap between these holders and the valve body, and when the valve is opened, fuel flows straight downward through the fuel flow passage and flows into the float chamber. It's summery.

By the way, at high temperatures in the summer, fuel vapor is generated in the fuel pipe system, and in order to prevent the so-called vapor lock in which the fuel supply amount decreases due to the bubbles,
One possibility is to increase the discharge pressure of the fuel pump. However, according to the above-mentioned needle valve structure, when the fuel discharge pressure is high, the fuel blown out from the needle valve will be sprayed directly toward the oil level in the float chamber, and this will cause the oil in the float chamber to The disadvantage is that the surface fluctuates greatly, causing a spilling phenomenon in which fuel is blown out from the nozzle or air vent pipe toward the mixture passage.

However, examples of prior art useful for solving this drawback include Japanese Utility Model Publication No. 53-38035 and Japanese Utility Model Publication No. 38035.
No. 50-106524 discloses that the fuel outlet is connected to the peripheral wall of the needle valve holder on which the valve body of the needle valve slides closely, and to the upper end of the holder. It is located opposite the space formed between the wall and the needle valve, and is positioned in a direction that prevents spilled fuel from falling onto the float and the lever that supports it. The fuel discharged downward into the valve holder immediately changes its direction in the diametrical direction of the holder and flows out from the outlet into the float chamber, and at this time, the discharge pressure of the fuel acts directly on the valve body, so that Since the valve body is pushed down, the float chamber is replenished with a larger amount of fuel than the specified amount, raising the oil level, resulting in a problem that the air-fuel ratio becomes rich and fuel consumption may increase.

In view of these circumstances, the present invention is designed to prevent the spilling phenomenon by filling the float chamber with fuel without disturbing oil level fluctuations even when the fuel discharge pressure is high, and to maintain the oil level almost constant. The purpose is to provide a needle valve with a

[Means for solving problems]

To achieve this purpose, the needle valve device of the present invention is
It is structured as follows. That is, a needle valve holder having an inlet is attached to the fuel passage in the upper part of the float chamber, and a valve body that opens and closes the inlet by a needle valve portion at the tip is closely inserted into the needle valve holder. A number of fuel outflow ports are formed in the peripheral wall of the needle valve holder, and fuel is introduced into the peripheral wall of the valve body in the axial direction from the needle valve part to the fuel outflow port, so that the needle valve receiving side is closed. Through these guide grooves and the fuel outlet, the fuel is directed radially outward of the needle valve holder and flows into the float chamber, so that the fuel does not flow straight down into the float chamber. At the same time, the valve body is characterized in that the effect of the fuel discharge pressure on the valve body is relaxed.

In addition, the needle valve described in Japanese Patent Application Laid-open No. 51-7337 has a valve body inserted into a needle valve holder with a gap, and a peripheral wall of the needle valve holder, an end wall, and a peripheral wall of the needle valve holder. A fuel outlet is provided to face the space formed between the valve body and the needle valve part, so that fuel from the fuel tank flows straight downward from the gap into the float chamber, and the fuel outlet By allowing more fuel to flow in, the resistance to the flow of fuel through the needle valve is reduced, and the discharge pressure of the fuel pump can be reduced. Therefore, this invention is different in purpose and structure from the present invention. .

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. In FIG. Mechanism 4 is attached. In the needle valve mechanism 4, a cylindrical needle valve holder 6 having a small-diameter inlet 5 is fixed in the fuel passage 3, and a valve body 7 is tightly inserted into this holder 6. The needle valve part 8 is inserted into and removed from the inflow port 5 to open and close the inflow port 5. In addition, a spring 9 is provided at the bottom of the valve body 7.
The valve stem 10 is placed on the needle valve receiver 13 of the float arm 12 that supports the float 11 in the float chamber 2, and
The valve body 7 is actuated via a spring 9 by the buoyancy of the valve body.

Next, as detailed in FIGS. 2 and 3, a fuel outlet 14 is provided around the entire circumference of the peripheral wall 6a of the needle valve holder 6.
A plurality of guide grooves 15 are formed, for example, in two stages, and the needle valve receiving side is closed in the axial direction from the needle valve part 8 to the fuel outlet 14 in the peripheral wall of the valve body 7. is formed to smoothly exchange the direction of the fuel flowing into the holder 6 in the axial direction to the outside in the radial direction, and to prevent the fuel discharge pressure from acting on the valve body 7.

Because of this configuration, when the engine is operating,
High fuel discharge pressure from the fuel pump acts on the valve body 7 of the needle valve 4, and in contrast, float buoyancy according to the oil level in the float chamber 2 acts on the needle valve receiver 13 and the valve shaft 1.
0 and acts on the valve body 7 through the spring 9 in opposition to the fuel discharge pressure. Therefore, when the oil level in the float chamber 2 drops and the float 11 lowers, the spring 9 stretches and the pressing force of the needle valve part 8 against the inlet 5 part becomes smaller. When the fuel discharge pressure becomes larger than this pressing force, the inlet 5 opens and the fuel that flows into the needle valve holder 6 changes its direction in the radial direction of the holder 6 and passes through the needle valve from the numerous fuel outlets 14. This causes the fuel to flow outward in the radial direction of the holder 6, reducing the force of the fuel and falling over a wide area on the oil surface of the float chamber 2, refueling without disturbing the oil surface and eliminating the spilling phenomenon. At the same time, the direction of the fuel can be changed in the radial direction of the needle valve holder 6, that is, in the direction of the fuel outlet 14, by using a plurality of holes surrounded by the peripheral wall of the holder 6 and provided in the axial direction on the peripheral wall of the valve body 7. As the force of the fuel becomes smaller due to flow resistance in the guide groove 15 of the needle valve 7
The fuel discharge pressure from the inlet port 5 that acts on the fuel is also relaxed, and as the oil level rises, the float also rises and the pressing force of the spring 9 becomes greater than the fuel discharge force, and the inlet port 5 closes to the needle valve. 8 to close and stop refueling. Therefore, the float chamber 2 oil level is
It is always kept constant, which prevents an increase in fuel consumption.

[Effect of idea]

As is clear from the above description, according to the present invention, when fuel with a high discharge pressure flows into the float chamber 2, the direction is changed to the outside in the radial direction of the needle valve holder 6, reducing the momentum, and gently floating the fuel. Since the fuel falls onto the oil surface in the chamber, turbulence in the oil surface is reduced and the spilling phenomenon is eliminated, and the direction change of the fuel is carried out within a plurality of guide grooves 15 formed in the axial direction on the peripheral wall of the valve body 7. Since this is carried out gradually, the influence of the fuel discharge pressure on the operation of the valve body 7 is small, and the oil level in the float chamber 2 is kept constant, so an increase in fuel consumption can be prevented.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the overall configuration of an embodiment of the needle valve of the present invention, FIG. 2 is an enlarged sectional view of the main parts,
FIG. 3 is a cross-sectional view taken from FIG. 2. 1... Carburetor body, 2... Float chamber, 3...
Fuel passage, 4... Needle valve mechanism, 5... Inflow port, 6...
... Needle valve holder, 6a... Peripheral wall portion, 7... Valve body, 8
... Needle valve part, 9 ... Spring, 10 ... Valve shaft, 11 ...
...Float, 12...Float arm, 13...
Needle valve receiver, 14...Fuel outlet, 15...Guide groove.

Claims (1)

[Scope of utility model registration request] A needle valve in which a needle valve holder having an inlet is attached to a fuel passage in an upper part of a float chamber, and a valve body that opens and closes the inlet by a needle valve portion at the tip is closely inserted into the needle valve holder, A number of fuel outflow ports are bored in the peripheral wall of the needle valve holder, and fuel is introduced into the peripheral wall of the valve body in the axial direction from the needle valve part to the fuel outflow port, and the needle valve receiving side is closed. A needle valve characterized by forming a plurality of guide grooves.