JPS6244111Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field]

The present invention relates to a needle valve that replenishes fuel according to a drop in the oil level in the float chamber in a carburetor of an internal combustion engine.In particular, when the temperature of the carburetor body or fuel is high, the fuel vaporizes and enters the needle valve passage. This relates to something that prevents the cut-off pressure from decreasing.

[Conventional technology and problems]

Generally, in this type of needle valve, a valve body is inserted into the valve chamber of a needle valve holder located above the float chamber so as to be moved up and down by the buoyancy of the float, and the pointed needle valve portion of this valve body guides it into the fuel inlet. It has a structure that allows it to be inserted to open and close. The fuel discharge pressure from the pump is high in the needle valve part of the fuel inlet, and the inside of the valve chamber on the opposite side of the fuel inlet of the needle valve part is at atmospheric pressure as well as the float chamber, so the fuel When the needle valve is opened and the gas flows into the valve chamber from the inlet, the pressure is reduced and the gas vaporizes. And the degree of this vaporization is
It is known that the temperature increases rapidly when the temperature of the entire carburetor or the fuel is high. By the way, while the valve chamber has a circular cross section, the valve body inserted therein has a rectangular cross section, and a flow passage for fuel is formed between the two, but this passage should not be made too large. Because it is not possible to
In the valve chamber, the vapor pressure of vaporized fuel accumulates in the area from just after the fuel inlet to the fuel flow passageway, that is, in the decompression section, and acts on the valve body, which pushes down the valve body and causes the needle valve to move. This results in a decrease in the closing pressure. Therefore, as the needle valve shut-off pressure decreases, the oil level in the float chamber becomes higher and the float buoyancy increases, causing the needle valve to close. This fluctuation in the oil level causes deterioration in fuel efficiency, etc. Moreover, the fuel vapor in the valve chamber described above disappears after the needle valve is closed. After that, when the oil level drops, the needle valve opens again and refueling starts, and the amount of bubble-like fuel generated in the float chamber also increases, causing this bubble-like fuel to leak into the mixture passage through the air vent pipe. , there is a problem that so-called spilling occurs. In view of these circumstances, the present invention provides a fuel vapor pressure communication hole that communicates the inside and outside of the valve body in the shoulder and cylindrical part of the valve body having the needle valve part, and further includes a fuel vapor pressure passage hole that is inserted into the inside of the spring. Fix the bar material to the float receiver,
A pressure reducing part is communicated within the valve body through the fuel vapor pressure communication hole in the shoulder of the valve body, and a pressure chamber is formed in which the volumetric volume of the rod is reduced, and the pressure reducing part of the valve chamber is connected to the pressure reducing part of the valve chamber. The generated fuel vapor pressure is quickly applied to the valve body in a pressure chamber inside the valve body, canceling out the influence of the fuel vapor pressure on the valve body, and thereby reducing the cut-off pressure when the needle valve closes. It is an object of the present invention to provide a needle valve that reliably prevents lowering.

[Means to solve the problem]

In order to achieve the above object, the present invention includes a needle valve holder screwed onto the fuel passage in the upper part of the float chamber, and a needle valve part installed in the valve chamber of the needle valve holder to open and close the fuel inlet. In a needle valve having a valve body and a float receiver that is fitted into the valve body through a spring and on which float buoyancy is applied, the inside and outside of the valve body are attached to the shoulder and cylindrical portion of the valve body that are in contact with the pressure reducing part. A communicating fuel vapor pressure communication hole is bored, a rod inserted inside the spring is fixed to the float receiver, and the pressure reducing part is connected to the valve body so that the fuel vapor pressure at the shoulder of the valve body is connected to the valve body. A pressure chamber is formed, which communicates through a conduction hole and whose volume is reduced by the volume of the rod so as to quickly generate a fuel vapor pressure substantially equal to the fuel vapor pressure generated in the decompression section. It's summery. In addition, examples of prior art related to the needle valve of a carburetor include, for example, Utility Model Application Publication No. 53-5621;
There are publications No. 41018 and Utility Model Application Publication No. 50-28115,
These do not deal with the vaporization of fuel, which is the subject of the present invention. In addition, in each of the above-mentioned publications, the lower end of the valve chamber is sealed and has a bottomed structure, but this causes problems such as fuel vapor pressure being generated in the valve chamber and deteriorating the flow of fuel. arise. Furthermore, in the prior art example disclosed in Japanese Patent Application Laid-open No. 1837-1983, in order to reduce the deflection of the float receiver that is fitted into the valve body and moves up and down, the fitting part between the valve body and the float receiver is lowered. In order to reduce the space between the valve body and the float, and to prevent the action of an air damper that occurs in the space between the valve body and the float, it is indicated that an air vent hole should be provided in the cylindrical part of the valve body. Therefore, this is different in purpose and configuration from the present invention.

【Example】

Hereinafter, the present invention will be specifically explained with reference to an embodiment of the drawings. In FIGS. 1 and 2, reference numeral 1 is a float chamber, and a needle valve 3 is attached to a fuel passage 2 in the upper part of the float chamber 1. It is being In the needle valve 3, a needle valve holder 6 having a small-diameter inlet 4 and a valve chamber 5 is screwed into the fuel passage 2, and a cylindrical valve body 7 with an open lower end is inserted into the valve chamber 5 so as to be movable up and down. A needle valve part 8 at the upper end of the valve body 7 is inserted into the inlet port 4 to gradually open and close it, and a float receiver 10 is provided below the valve body 7 via a spring 9.
is fitted, but the inner circumference of the valve body 7 and the float receiver 10
A narrow space 16 is provided between the valve body 7 to allow the float receiver 10 to move relative to the valve body 7, so that the inside of the valve body 7 can be connected to the float chamber 1 through the space 16. It will be communicated. Further, a pressure reducing part 5a is formed in the valve chamber 5, where the fuel expands by suddenly widening immediately after the inlet 4, and the fuel flows between the needle valve holder 6 and the valve body 7 from this pressure reducing part 5a. It communicates with the inside of the float chamber 1 via the passage 5b. Next, a float arm 12 is attached to one side of the float 11 provided inside the float chamber 1, and the float arm 12 is suspended from a support 13 inside the float chamber 1 along the needle valve holder 6.
The float chamber 1 is pivoted by the shaft 12'.
The float 11 is made to swing up and down depending on the oil level height. In this case, in view of the fact that the float arm 12 moves up and down together with the float 11, a needle valve receiving member 14 is provided at a position directly below the needle valve of the float arm 12, and the needle is placed on this needle valve receiving member 14. The float receiver 10 of the valve 3 is mounted, and the needle valve part 8 of the valve body 7 is moved in conjunction with the vertical movement of the float 11.
It is designed to be opened and closed by In this configuration, a fuel vapor pressure communication hole 15a is formed in the shoulder portion 7a of the valve body 7, and the fuel vapor pressure communication hole 15a is formed in the shoulder portion 7a of the valve body 7 to communicate the pressure reduction portion 5a with the inside of the valve body 7.
A fuel vapor pressure communication hole 15b is provided in b to communicate the fuel flow passage 5b with the inside of the valve body 7, and the fuel vapor pressure generated in the pressure reducing part 5a of the valve chamber 5 is introduced into the valve body 7. At this time, the fuel vapor pressure is immediately introduced into the inside of the valve body 7 through the fuel vapor pressure communication hole 15a formed in the shoulder 7a of the valve body 7 facing the pressure reducing part 5a. The fuel enters the inside of the valve body 7 through the fuel vapor pressure communication hole 15b formed in the cylindrical portion 7b of the valve body 7. By the way, the float receiver 10 is fitted into the opening at the lower end of the valve body 7, and the inside of the valve body 7 is communicated with the float chamber 1 through the narrow gap 16 as described above. A part of the fuel vapor pressure introduced into the valve body 7 is transferred from the above-mentioned gap 16 to the float chamber 1.
However, by setting the sizes of the fuel vapor communication holes 15a and 15b so that a larger amount of fuel vapor pressure than this leaking fuel vapor pressure is introduced into the valve body 7, the fuel vapor pressure is not introduced into the valve body 7. It becomes possible to cause the pressure of the fuel vapor to act upwardly on the valve body 7 within the valve body 7, in contrast to the pressure of the fuel vapor acting downwardly on the outside of the valve body 7 in the pressure reducing part 5a. . However, since the volume inside the valve body 7 is several times larger than the volume of the pressure reducing part 5a, the volume of the valve body 7 is
There is a time delay in the rise in pressure within the valve body 7, and as mentioned above, part of the pressure within the valve body 7 leaks through the narrow gap 16 between the valve body 7 and the float receiver 10, so this state remains as it is. Then, inside the valve body 7, there is a pressure reducing part 5a.
It is not possible to generate a fuel vapor pressure substantially equal to the fuel vapor pressure at . Therefore, a rod 17 for reducing the volume is inserted inside the spring 9 on the float receiver 10 side in the valve body 7 and fixed to the float receiver 10, and the valve body By reducing the volume inside to form the pressure chamber 18, the pressure chamber 1 inside the valve body 7 is reduced.
8, the fuel vapor pressure which is approximately equal to the fuel vapor pressure generated in the pressure reducing part 5a can be applied quickly. Since the present invention is configured in this way, the force that compresses the spring 9 through the needle valve receiving member 14 and the float receiving member 10 due to the fuel discharge pressure from the fuel pump and the buoyant force of the float 11, that is, the force of compressing the spring 9 through the needle valve receiving member 14 and the float receiving member 10, is reduced. Needle valve part 8
The pressing force against the inlet 4 acts on the needle valve portion 8 in opposition. Therefore, when the oil level in the float chamber 1 decreases and the float buoyancy decreases, the float receiver 10 descends as the oil level decreases, and together with the spring force of the spring 9, the pressing force of the needle valve portion 8 of the valve body decreases. As a result, the valve body 7 retreats due to the fuel discharge pressure, the inlet port 4 opens, and fuel flows from the inlet port 4 into the valve chamber 5, and then flows down the fuel flow passage 5b and is replenished into the float chamber 1. Ru. When the oil level in the float chamber 1 rises, the float buoyancy also increases and the float receiver 10 also rises, which increases the spring force of the spring 9 and the pressing force of the needle valve part 8 of the valve body against the inlet 4. When the fuel discharge pressure is overcome, the inlet port 4 is closed by the needle valve part 8, and in this way, a constant level of fuel is always maintained in the float chamber 1. . By the way, during the opening/closing operation of the needle valve 3, especially when refueling the float chamber 1 by opening the valve, when the fuel flows into the valve chamber 5 from the inlet 4, the constricted state in the pressure reducing part 5a is suddenly released. inflates. that time,
When the temperature of the vaporizer body or fuel is high, fuel components with low boiling points are easily vaporized and high vapor pressure is generated in the pressure reducing section 5.
Occurs in a. Although this fuel vapor pressure passes sequentially through the fuel flow passage 5b together with the fuel, there is a limit to it, and this fuel vapor pressure is constantly generated during refueling, so that the fuel vapor accumulated in the pressure reducing section 5a The pressure acts on the valve body 7 to push it down, and thus the valve body 7 is pushed down against the spring force of the spring 9, resulting in a decrease in the needle valve shutoff pressure. However, at this time, the fuel vapor pressure in the pressure reducing part 5a is lower than the shoulder part 7a of the valve body 7 facing the pressure reducing part 5a.
The fuel quickly flows down through the fuel vapor pressure communication hole 15a formed in the cylindrical portion 7b of the valve body 7, and quickly flows down the fuel flow passage 5b together with the fuel. The pressure chamber 1 enters inside the body 7 into a narrow pressure chamber 18 formed by the float receiver 10 and the rod 17 of the valve body 7.
The fuel vapor pressure in the pressure chamber 18 quickly increases
A fuel vapor pressure approximately equal to the fuel vapor pressure generated in the depressurizing section 5a is generated within the depressurizing section 5a. Then, the fuel vapor pressure in the pressure chamber 18 is applied to the valve body 7 in the pressure reducing part 5a.
By acting quickly against the fuel vapor pressure at When the oil level in the float chamber 1 reaches the set value, the needle valve 3 is reliably closed without any additional replenishment. The fuel vapor pressure in the pressure chamber 18 acts to push down the float receiver 10, but the shaft 12' that pivotally supports the float arm 12 and the float arm 1
The distance between the contact part with the needle valve receiving material 14 of No. 2 is
The pressure chamber 18 is extremely small compared to the distance between the shaft 12' and the vertical line passing through the center of the buoyancy of the float 11, and the oil surface resistance to the sinking of the float 11 is considerably large. Due to the fuel vapor pressure within, the float receiver 10 is hardly pressed down, and as a result, the spring force of the spring 9 is hardly reduced, so that the needle valve part 8 is not opened any further.

[Effect of the idea]

As is clear from the above description, according to the present invention, due to the structure of the needle valve 3, especially when the temperature of the carburetor main body or the fuel is high, the fuel vapor pressure generated when the fuel flowing down from the inlet port 4 is vaporized is This causes the needle valve cut-off pressure to drop and excess fuel to be supplied to the float chamber. Since it is quickly and reliably prevented by acting on the body 7, deterioration of fuel efficiency etc. due to oil level fluctuations does not occur. Furthermore, since the generation of foamy fuel from the needle valve 3 is kept to a minimum, spilling in which foamy fuel leaks into the air-fuel mixture passage is also prevented. Furthermore, since the rod 17 is installed long inside the spring 9, arrhythmia of the spring 9 is suppressed and the function of the needle valve 3 is improved.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an example of a vaporizer to which the present invention is applied, and FIG. 2 is a cross-sectional view showing an example of a needle valve according to the present invention. 1... Float chamber, 2... Fuel passage, 3... Needle valve, 4... Inflow port, 5... Valve chamber, 5a... Pressure reducing part, 6... Needle valve holder, 7... Valve body, 7a ...Shoulder part, 7b...Cylinder part, 8...Needle valve part, 9...Spring,
10... Float receiver, 15a, 15b... Fuel vapor pressure communication hole, 17... Bar, 18... Pressure chamber.

Claims (1)

[Scope of utility model registration request] A needle valve holder is screwed into the fuel passage in the upper part of the float chamber, and a valve body is installed inside the valve chamber of the needle valve holder and has a needle valve part that opens and closes the fuel inlet, and the valve body is fitted into the valve body via a spring. In a needle valve having a float receiver that is inserted into the needle valve and on which a float buoyant force is applied, the valve body includes:
A fuel vapor pressure communication hole communicating between the inside and outside of the valve body is bored in the shoulder and cylindrical part that are in contact with the pressure reducing part, and a rod to be inserted inside the spring is fixed to the float receiver. communicating the pressure reduction part into the valve body through the fuel vapor pressure communication hole in the shoulder of the valve body;
A needle valve characterized in that the volume of the rod forms a pressure chamber whose volume is reduced so as to quickly generate a fuel vapor pressure substantially equal to the fuel vapor pressure generated in the pressure reducing section.