JPS6315570Y2 - - Google Patents

Description

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

The present invention relates to the improvement of carburetors used in general-purpose engines and the like.

[Conventional technology]

Figures 1 and 2 show an example of a carburetor used in a general-purpose engine. In these figures, numeral 1 is a general-purpose engine body, 2 is a generator driven by this engine body 1, and this is a vibration-proof rubber 3.
It is installed on the base 4 via. A carburetor 5 is fixed to protrude from one side of the engine body 1, an air cleaner 6 is connected to the outside of the carburetor 5, and a muffler 7 is protruded from the opposite side of the generator 2. A control box 8 is fixed to.

[Problem that the invention attempts to solve]

In such a configuration, due to the arrangement of each member, the carburetor 5 absorbs the hot air reflected from the engine body 1 after colliding with the generator 2, and the muffler 7.
If the entire carburetor 5 reaches a certain temperature or higher, the pressure inside the float chamber will rise and the fuel supply into the float chamber will become insufficient, causing the throttle valve to open fully. The engine may stop due to lack of fuel during operation. Conventionally, in order to eliminate the fuel supply shortage caused by the pressure increase in the float chamber when the carburetor is at high temperature, it has been considered to increase the cross-sectional area of the air vent passage, but conventional methods have As seen in the publications of Utility Model Application No. 55-116850 and Utility Model Application No. 55-116851, because the cross-sectional area was always constant, that is, it was a fixed hole, the damping effect of the float was lost and the fuel supply became unbalanced. There was a problem. This invention solves the above-mentioned problem by increasing the cross-sectional area of the air vent passage only when the pressure in the float chamber increases and the fuel supply becomes insufficient, ensuring that the fuel supply is always adequate regardless of temperature conditions. It is an object of the present invention to provide a carburetor capable of supplying fuel with a simple structure and with the addition of a control valve that operates reliably.

[Means to solve the problem]

In order to achieve this object, the carburetor of the present invention includes a holding part held in the air vent passage that communicates the float chamber with the atmospheric pressure side;
A control valve is provided that includes a constriction part that changes the cross-sectional area of the passage by temperature sensing, and the constriction part is composed of a plurality of tapered tongues, and the both side edges of each tongue are adjacent to each other at room temperature. It is formed into a truncated cone shape by being removably joined to the side edge of the tongue, and is configured so that the opening area increases by expanding the constricted portion at high temperatures. Furthermore, in Japanese Utility Model Publication No. 38-24311, which is an example of prior art, a through hole that communicates with the atmosphere is provided in the upper part of the float chamber, and a valve body that opens and closes the through hole and the hole of the air vent pipe. There is a vaporizer that sometimes opens a vent hole and closes the air vent pipe to prevent the occurrence of percolation. A thermally deformable body in the shape of an inverted truncated cone made of a bimetal plate is arranged to cover the ventilate part,
A carburetor in which this thermally deformable body changes the diameter of the reduced diameter part at the lower end according to the intake air temperature, changes the effective cross-sectional area of the ventilate part, and allows the engine to take in a mixture according to the intake air temperature. has been done.

【Example】

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. In FIG. 3 showing an embodiment of the present invention, reference numeral 5 denotes a carburetor, and this carburetor 5 connects a float chamber body 11 and a mixing body 12, and has a float chamber inside surrounded by
3 is formed. A needle valve 15 that is opened and closed by a float 14 provided in this float chamber 13
is provided at the opening end of the fuel feed passage 16 to the float chamber 13, and the intake passage 1 formed in the mixing body 12 from the main nozzle 18 via the main jet 17 provided at the bottom of the float chamber 13.
The fuel is supplied to the bench lily section 9. An air vent passage 21 that communicates the air chamber part 20 above the float chamber 13 with the outside air is formed to have a larger cross-sectional area than a normal one,
This air vent passage 21 is provided with a control valve 22 that is activated by sensing temperature. As shown in FIGS. 4 to 6, the control valve 22 is constructed by pasting a metal plate 23 that is highly deformed by heat and a metal plate 24 that is deformed little. are formed at intervals, and a plurality of tapered tongue pieces 26 are provided between them, and the other end is formed into a cylindrical shape with the metal piece 23 having a large thermal deformation inside, and the tongue pieces 26 are A cylindrical body 22a formed by molding into a truncated cone shape, and a truncated conical body formed integrally with the cylindrical body 22a, in which both side edges of each tongue piece 26 are removably connected to the side edges of the adjacent tongue piece 26. It consists of a constricted portion 22b. The cylindrical body 22a of the control valve 22 configured in this way is shown in FIGS.
As shown in FIG. 8, it is fitted and fixed near the open air side opening of the air vent passage 21, and the throttle part 22b projects inward. In the carburetor constructed as described above, when the temperature of the mounting part of the control valve 22 is low, the throttle part 22b of the control valve 22 is closed and the tongues 26 are connected to each other, as shown in FIG. The cross-sectional area of the air vent passage 21 is made equal to the cross-sectional area of the air vent passage 21 of a normal carburetor due to the throttle portion 22b. However, when the carburetor 5 is heated by radiant heat from the muffler 7 and the temperature of the mounting part of the control valve 22 rises, the tongues 26 separate from each other due to thermal deformation, and the constricted part 22b gradually expands.
As shown in FIG. 8, the opening cross-sectional area of the aperture portion 22b increases. Therefore, the pressure inside the float chamber 13 is not increased, and the fuel supply passage 16 is connected to the float chamber 13 via the needle valve 15.
3 is prevented from becoming insufficiently supplied with fuel. As shown in FIG. 9, the opening cross-sectional area of the throttle portion 22b of the control valve 22 of this embodiment gradually increases when the temperature exceeds 20°C, and becomes fully open when the temperature reaches 80°C. Note that when the temperature of the attachment part of the control valve 22 decreases, the throttle part 22b closes and its opening cross-sectional area decreases. In this invention, the control valve can be constructed from a single metal plate that has large thermal deformation, instead of pasting together a metal plate that has large thermal deformation and a metal plate that has small thermal deformation, as in the previous embodiment. In addition, when the metal plate is formed into a cylindrical shape, it is preferable that the joints on both sides of the metal plate be formed into a shape that bites into each other, such as an S-shape, rather than a straight line.

[Effect of the idea]

As explained above, according to the present invention, the air vent passage that communicates the float chamber with the atmospheric pressure side is provided with
By installing a control valve and increasing the cross-sectional area of the passage only at high temperatures, the pressure inside the float chamber can be kept almost constant regardless of temperature conditions, and fuel supply shortages at high temperatures can be prevented. The control valve can be used in higher temperature conditions than the conventional one, and does not cause imbalance in fuel supply, which is the case with the case where the cross-sectional area of the air vent passage is constantly increased.
The truncated conical constriction part is formed integrally with the cylindrical body and is made up of tongues that are divided into a plurality of pieces in the circumferential direction.These tongues easily deform elastically due to heat.
Since the opening cross-sectional area of the air vent passage can be concentrically controlled, the configuration is simple and reliable operation is achieved.

[Brief explanation of the drawing]

1 and 2 are a side view and a partial plan view showing an example of the use of a carburetor, FIG. 3 is a longitudinal cross-sectional view showing an embodiment of the present invention, and FIG. 4 is a partially exploded view of a control valve material. Figures 5 and 6 are a half-cut side view and rear view of the control valve, Figures 7 and 8 are partial cross-sectional views showing the control valve section at low temperatures and high temperatures, respectively, to explain usage conditions. It is a figure showing the relationship between temperature of a control valve and opening cross-sectional area. 1... Engine body, 2... Generator, 3... Anti-vibration rubber, 4... Base, 5... Carburetor, 6
...Air cleaner, 7...Muffler, 8...Control box, 11...Float chamber body, 1
2...Mixing body, 13...Float chamber,
14...Float, 15...Needle valve, 16...
...Fuel feed passage, 17...Main jet, 18
... Main nozzle, 19 ... Intake passage, 20 ... Air chamber section, 21 ... Air vent passage, 22 ... Control valve, 22a ... Cylindrical body, 22b ... Throttle section, 23,
24...metal plate, 25...V-shaped groove, 26...tongue piece.

Claims (1)

[Scope of utility model registration request] A control valve is provided in the air vent passage that communicates the float chamber with the atmospheric pressure side, and includes a holding part held in the passage, and a throttle part that changes the cross-sectional area of the passage by temperature sensing, and the throttle part consists of a plurality of tapered tongues, which are formed into a truncated cone shape by connecting both side edges of each tongue to the side edges of the adjacent tongue so that they can be moved into and out of contact with the side edges of the adjacent tongue at room temperature; A carburetor characterized in that the carburetor is configured so that its opening area increases by expansion.