JPS6313412Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to the float chamber structure of a carburetor in a vehicle internal combustion engine, and particularly when fuel bubbles from the needle valve and flows into the float chamber at high temperatures. This invention relates to a device that closes the needle valve early and prevents the spilling phenomenon.

[Prior Art] In general, a carburetor float chamber is configured such that a needle valve opens and closes a fuel inlet port using the buoyancy of the float, so that an appropriate amount of fuel is always stored in the float chamber. Therefore, when the temperature of the carburetor body or fuel is high, when fuel flows from the small-diameter fuel inlet to the large-diameter valve chamber of the needle valve and expands,
Low boiling point components of gasoline fuel may easily vaporize and form bubbles and flow into the float chamber.

By the way, as mentioned above, when the fuel flows into the float chamber in the form of bubbles, the fuel vapor pressure increases, suppressing the rise in the oil level, and lengthening the time until the needle valve is closed. As a result, a large amount of fuel vapor accumulates in the upper space of the float chamber, and the vapor and bubbles overflow into the air-fuel mixture passage through the vent pipe, causing the air-fuel mixture to become too rich and cause poor running. It is known that this phenomenon occurs.

Therefore, as one of the conventional measures to prevent such spilling, the gasket inserted into the joint between the carburetor and the suction pipe is made of a highly insulating material, which reduces this heat transfer from the engine body and increases the temperature of the carburetor. There are ways to suppress this, but they are too indirect and have little effect. On the other hand, as a direct solution, there is, for example, the prior art disclosed in Japanese Utility Model Application Publication No. 53-14031, in which the interior of the float chamber is partitioned into the needle valve and the float side, and a fuel flow path that bypasses the partition plate is separately provided. It is proposed that it be attached.

Furthermore, Japanese Patent Application Laid-Open No. 52-94932 discloses that the fuel is not allowed to flow directly into the float chamber, but instead is allowed to flow into the lower part of the float chamber from a fuel passage formed on the wall surface of the carburetor main body.

[Problems to be solved by the invention] However, in the former prior art, since the upper space in the float chamber is in a communicating state, leakage of fuel vapor through the vent pipe cannot be prevented, and furthermore, the fuel flow path is The structure is complicated due to the necessity of separately attaching the fuel tank, which may cause problems in the flow of fuel, which is undesirable.

Further, in the latter prior art, even if the opening of the fuel passage is opened below the fuel liquid level, there is a problem that air bubbles flow into the float chamber together with the fuel because the fuel passage is narrow.

In view of the problems in the conventional technology, the present invention has been developed to solve the problems without causing any inconvenience in structure or function.
When fuel flows into the float chamber in the form of bubbles,
To provide a float chamber structure of a carburetor which closes a needle valve early and directly prevents fuel vapor and bubbles in the upper space of the float chamber from overflowing through a vent pipe.

[Means for Solving the Problems] For this purpose, the float chamber structure according to the present invention has a vent pipe and a float arranged in a float chamber formed in the carburetor body, and a fuel passage to the float chamber. In a carburetor provided with a needle valve, the needle valve is operated by a float arm provided on the side of the float chamber to control the inflow of fuel from the fuel passage, from the upper space in the float chamber. A partition wall submerged below the liquid level of the fuel is provided to separate the float chamber into two chambers, and
The two chambers are formed in communication below the fuel liquid level below the partition wall, and one of the two chambers is provided with the vent pipe and the float, and the other chamber is provided with the fuel passage and the needle valve. The float arm is configured to abut the needle valve through the lower part of the partition wall.

[Embodiment] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the drawings, reference numeral 1 indicates a carburetor body, 2 a float chamber, and a fuel passage 3 to the float chamber 2. A needle valve 4 is attached, and a float 5 is inserted inside the float chamber 2. A needle valve holder 7 having a small diameter inlet 6 in the fuel passage 3 is screwed onto the needle valve 4, and the inlet 6 is provided inside the holder 7.
A valve body 9 having a pointed needle valve portion 8 that engages with the valve body to open and close it is movably inserted, and a spring 10 and a float receiver 11 are connected to the valve body 9. .

In such a configuration, the needle valve 4 in the float chamber 2
A partition wall 12 extending from the upper space to a part of the fuel is suspended between the upper space and the float 5 to separate the needle valve side chamber 2a and the float side chamber 2b. and the float-side chamber 2b are in communication with each other below the fuel liquid level below the partition wall 12. Then, the float arm 13 from the float 5 is attached to the partition wall 12.
passing under the needle valve 4 and extending to the side of the needle valve 4 and supporting body 1
This float arm 1 is rotatably supported on
A float receiver 11 of the needle valve 4 is placed on a needle valve receiver 15 that stands up from the needle valve 3, and the needle valve 4 is opened and closed by the action of a float arm 13 based on the buoyancy of the float 5.

Because of this configuration, the float chamber 2
The fuel inside communicates under the partition wall 12, and normally it is exactly the same as without the partition wall 12, and the fuel level in the needle valve side chamber 2a and the float side chamber 2b is always the same. The upper space is completely separated by a partition wall 12 into a chamber 2a on the needle valve side and a chamber 2b on the float side, and a fuel passage to a vent pipe, nozzle, etc. (not shown) is connected to the chamber 2b on the float side. .
In addition, since the float 5 is located on the side of the float-side chamber 2b divided by the partition wall 12, it moves up and down depending on the fuel level in the float-side chamber 2b. Since the fuel liquid level in the side chamber 2b is the same, there is no difference from the conventional case.

On the other hand, when fuel flows in the form of bubbles from the needle valve 4 at high temperatures, the bubbles first stay only in the chamber 2a on the needle valve side and accumulate there, and the partition wall 12 prevents them from flowing into the chamber 2b on the float side. Since it is blocked, overflow through the vent pipe is completely eliminated. Then, as air bubbles accumulate in the chamber 2a on the needle valve side and the internal vapor pressure increases, the oil level in the chamber 2a on the needle valve side is pushed downward as indicated by the dashed line L. On the other hand, the oil level on the float-side chamber 2b side rises as shown by the dashed line L, the float 5 rises, and the shut-off pressure of the needle valve 4 increases.In this way, the needle valve 4 is reliably closed and excess fuel is removed. There will be no inflow.

[Effect of the invention] As is clear from the above explanation, according to the invention, the upper space in the float chamber 2 is completely separated by the partition wall 12 into two chambers: one on the needle valve 4 side and the other on the side of the float 5 and vent pipe. However, the two chambers are communicated with each other under the fuel liquid level below the partition wall 12, and even if fuel flows into the needle valve side chamber 2a from the needle valve 4 in the form of bubbles at high temperatures, the bubbles will not flow through the vent pipe. Since the air does not flow into the chamber 2b on the float side, spilling due to air bubbles overflowing from the vent pipe is reliably prevented.

Further, when the fuel from the needle valve 4 turns into bubbles and flows into the needle valve side chamber 2a, the vapor pressure acts on the fuel liquid level in the needle valve side chamber 2a, causing the float side chamber 2b to flow into the needle valve side chamber 2a.
The fuel level rises, causing the float 5 to rise quickly and closing the needle valve 4, which reduces the amount of bubbles flowing in and prevents the occurrence of spilling.

[Brief explanation of drawings]

The drawing is a sectional view showing an embodiment of the float chamber structure according to the present invention. 1... Carburetor body, 2... Float chamber, 2a...
...Chamber on the needle valve side, 2b...Chamber on the float side, 3...
Fuel passage, 4... Needle valve, 5... Float, 6...
Inflow port, 7... Needle valve holder, 8... Needle valve part, 9...
... Valve body, 10 ... Spring, 11 ... Float receiver, 12 ... Partition wall, 13 ... Float arm, 14 ... Support body, 15 ... Needle valve receiver.

Claims (1)

[Scope of Claim for Utility Model Registration] A vent pipe and a float are provided in a float chamber formed in the carburetor body, a needle valve is provided in the fuel passage to the float chamber, and a needle valve is provided on the side of the float chamber. In the carburetor, the needle valve is operated by a float arm to control the inflow of fuel from the fuel passage. The float chamber is divided into two chambers, and the two chambers are communicated with each other under the fuel liquid level below the partition wall, and the vent pipe and the float are arranged in one of the two chambers, and the other A float chamber structure for a carburetor, characterized in that the fuel passage and the needle valve are disposed in the chamber, and the float arm abuts the needle valve through the lower part of the partition wall.