JP2003083170A - Rotary throttle valve-type carburetor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary throttle valve-type carburetor of smooth operation, having a narrow contact area with a valve chest of a carburetor body even when the outer shape of a throttle valve is large. SOLUTION: Lattice-shaped projections 72-74, 75 or a spiral projection 76 abutted on the valve chest 57 are formed on an outer peripheral face of the throttle valve 47, and the other part is thinned 70, or provided with spiral grooves 68, 69 like a surface of a muskmelon. Whereby the contact area of the throttle valve 47 and the valve chest 57 is narrowed, the sliding resistance is reduced, and the throttle valve 47 is smoothly operated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary throttle valve type carburetor for a small general-purpose internal combustion engine mounted on a portable working machine such as a power saw, and more particularly to a rotary operation in which a contact area with a valve chamber is narrow and the operation is smooth. The present invention relates to a throttle valve vaporizer.

[0002]

2. Description of the Related Art A rotary throttle valve type carburetor is widely used in small-sized general-purpose internal combustion engines because it has a small number of processed parts due to its structure and is suitable as a countermeasure against emission. However, in the large diameter carburetor required for internal combustion engines mounted on power saws, the outer shape of the throttle valve also becomes large, the contact area with the carburetor main body becomes large, and the processing area of the surface of the throttle valve is wide. Therefore, the service life of the machined tool is shortened. In addition, the throttle valve may malfunction due to ice accretion caused by icing (cutting out ice blocks).

[0003]

SUMMARY OF THE INVENTION In view of the above problems, the object of the present invention is to provide a rotary throttle valve type in which the operation area is smooth and the contact area with the valve chamber of the carburetor main body is narrow even if the outer shape of the throttle valve is large. To provide a vaporizer.

[0004]

In order to solve the above-mentioned problems, the structure of the present invention is provided with a grid-shaped ridge on the outer peripheral surface of the throttle valve, which contacts the valve chamber of the carburetor main body. The feature is that meat is removed from the part.

According to the structure of the present invention, the upper and lower ends of the outer peripheral surface of the throttle valve are provided with annular ridges which come into contact with the valve chamber of the carburetor body, and the intermediate portion is axially brought into contact with the valve chamber of the carburetor body. A ridge and a spiral ridge are provided, and the other portion of the outer peripheral surface is lightened.

Further, the structure of the present invention is characterized in that the outer peripheral surface of the throttle valve is provided with spiral grooves which do not contact the valve chamber of the carburetor main body and intersect each other.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, as a throttle valve of a rotary throttle valve type carburetor, the outer peripheral surface of the throttle valve is a cylindrical surface in order to narrow the contact area with the valve chamber and obtain a smooth operation of the throttle valve. Instead of leaving it as it is, the outer peripheral surface is subjected to lightening processing. For this reason,
The outer peripheral surface of the throttle valve is provided with grid-shaped or spiral ridges which come into contact with the valve chamber, or spiral grooves which intersect each other like the surface of the muskmelon are provided.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, in a rotary throttle valve type carburetor, a cylindrical valve chamber 57 orthogonal to the intake passage 16 is formed in the carburetor body 15, and a throttle valve 47b is provided in the valve chamber 57. 47 is rotatably and vertically movable. Throttle valve 4
The throttle valve lever 51 is coupled to the shaft portion 47a which protrudes upward from 7 through the cover plate 53 which closes the valve chamber 57.
A cam mechanism is composed of the lower cam surface 51 a of the throttle valve lever 51 and the follower 52 of the cover plate 53. When the throttle valve 47 rotates the throttle valve 47 in the acceleration direction against the force of the return spring 54 by the throttle valve lever 51, the opening degree of the throttle hole 47b communicating with the intake passage 16 increases, and at the same time, the shaft portion 47a of the throttle valve 47. The needle valve 55 protruding from the nozzle hole 47b to the throttle hole 47b and fitted into the fuel nozzle 56 rises from the injection hole 56a of the fuel nozzle 56, and the opening degree of the injection hole 56a increases. The stationary fuel nozzle 56 is fitted and supported in a hole 58 in the bottom portion of the main body 15, and the constant pressure fuel chamber 25 of the fuel metering mechanism A has a check valve 66 and a jet 59.
Through the injection hole 56a.

A fuel pump 11 and a fuel metering mechanism A are formed under the carburetor main body 15. That is, the fuel pump 1
Reference numeral 1 denotes a pulsating pressure chamber 8 that connects an intermediate wall 49 to the lower end surface of the main body 15 with the membrane 10 interposed therebetween, and accommodates a spring 8a above the membrane 10.
And a pump chamber 9 is defined below the membrane 10.
In the four-stroke engine, the fuel pump 11 is the intake passage 6 of the heat insulation pipe 63.
The pulsating intake negative pressure of 3a is introduced into the pulsating pressure chamber 8 through the inlet 61a and the passage 61, and in the two-stroke engine, the pulsating pressure of the crank chamber is introduced into the pulsating pressure chamber 8 to remove the fuel in the fuel tank 37. The gas is sucked into the pump chamber 9 through the pipe 38, the inlet 13, the check valve 12 and the passage 12a, and is discharged into the passage 7a through the passage 12a and the check valve 7.

In the fuel metering mechanism A, the cover 30a is connected to the lower end surface of the intermediate wall 49 with the membrane 29 interposed therebetween, and the constant pressure fuel chamber 25 is provided.
And the air chamber 30 is divided. A lever 28 is rotatably supported by a shaft 27 inside the constant pressure fuel chamber 25. Lever 2
One end of 8 is engaged with the inflow valve 2 and the inflow valve 2 has a spring 24
Is configured to come into contact with the valve seat at the end of the passage 7a. The other end of the lever 28 can be brought into contact with a protrusion at the center of the membrane 29, and when the atmospheric pressure and the suction negative pressure acting on the membrane 29 become larger than the force of the spring 24, the lever 28 moves clockwise. The inflow valve 2 is rotated to open and the fuel is supplied to the constant pressure fuel chamber 25 from the passage 7a.
Holds a predetermined amount of fuel at a predetermined pressure. The fuel in the constant pressure fuel chamber 25 is supplied to the intake passage 16 through the check valve 66, the jet 59, the injection hole 56a of the fuel nozzle 56, and the throttle hole 47b. In the illustrated embodiment, an intake passage 63 connected between the intake port of the engine and the carburetor main body 15 in order to prevent accumulation of fuel.
A ring member 26 made of a metal having a large thermal conductivity, such as aluminum, having an inner diameter smaller than that of the heat insulating tube 63 having a.
Is fitted into the outlet of the intake passage 16.

An air purifier is connected to the end portion 15a of the main body 15, and an end portion 15b is connected to an intake port (not shown) of the engine through a gasket 62 and a heat insulating pipe 63. When the engine is operating, the intake air sucked into the intake passage 16 passes through the throttle hole 47b of the throttle valve 47, and the injection hole 56a of the fuel nozzle 56.
The fuel is sucked from and is supplied to the engine as a mixture through the throttle hole 47b, the intake passage 16 and the heat insulating pipe 63.

As shown in FIG. 2, the throttle valve 47 is integrally provided with a shaft portion 47a projecting to the upper end portion, and the throttle hole 4 is provided.
The bottom of 7b is provided with a through hole 56b through which the fuel nozzle 56 penetrating in the axial direction penetrates. The outer peripheral surface of the throttle valve 47 is provided with an annular ridge 72 surrounding the upper end portion, an annular ridge 73 surrounding the central portion, and an annular ridge 74 surrounding the lower end portion. Surrounding annular projection 80
Is provided. Further, a plurality of axial protrusions 75 are provided at intervals in the circumferential direction, and the protrusions 75 are protrusions 72 to 74.
Intersect with. A so-called lightening 70 is applied to a portion of the outer peripheral surface of the throttle valve 47 which does not have a ridge so as to make the thickness thin and uniform. The ribs 72 to 75 of the throttle valve 47 and the thinned portion 70 are integrally molded when the throttle valve 47 is molded from synthetic resin or die cast from aluminum alloy. Then, after forming the throttle valve 47, each of the ridges 72 to 75
Is machined to form a smooth cylindrical surface (envelope).

In the embodiment shown in FIG. 3, an annular projection 72 is provided at the upper end of the outer peripheral surface of the throttle valve 47, and an annular projection 73 is provided at the intermediate portion.
However, annular projections 74 are respectively provided at the lower ends, annular projections 80 surrounding the throttle holes 47b are formed, and a plurality of axial projections 75 are arranged at predetermined intervals in the circumferential direction. Provided on the outer peripheral surface of the throttle valve 47.
The portion without 75 and 80 is lightened 70.

As shown in FIG. 4, a spiral ridge 76 may be provided between the annular ridge 72 at the upper end of the throttle valve 47 and the annular ridge 74 at the lower end. Also in this embodiment, the annular projection 80 surrounding the edge of the throttle hole 47b and the axial projection 75 are provided.
Is provided. The inclination of the spiral ridge 76 is preferably set in a screw direction so that the throttle valve 47 rises when the throttle valve 47 is rotated in the acceleration direction.

In the embodiment shown in FIG. 5, spiral grooves 68 and 69 are provided on the outer peripheral surface of the throttle valve 47 having a smooth cylindrical surface, and the inclination directions of the grooves 68 and 69 are opposite to each other. Preferably, an annular ridge 73 surrounding the outer peripheral surface is provided at the central portion of the throttle valve 47 in the axial direction. Instead of providing the grooves 68 and 69, a large number of hemispherical recesses may be provided on the outer peripheral surface of the throttle valve 47.

[0016]

As described above, according to the present invention, the outer peripheral surface of the throttle valve is provided with a grid-shaped or spiral-shaped ridge which comes into contact with the valve chamber, and the other portion of the outer peripheral surface is subjected to lightening processing or throttling. Since the spiral groove that crosses each other like the surface of muskmelon is provided on the outer peripheral surface of the valve, the contact area with the valve chamber is narrowed, sliding resistance is reduced, and smooth operation of the throttle valve can be obtained. .

By making the protrusions (ribs) to be left on the throttle valve spiral so as to rise in the rotation direction (acceleration direction) of the throttle valve,
Smooth operation of the throttle valve can be obtained, and the effect of scraping ice deposits is expected.

Since the thinning process is obtained by integrally molding the throttle valve from synthetic resin or aluminum alloy, the processing area of the outer peripheral surface of the throttle valve which is in contact with the valve chamber is reduced and the productivity is improved.

[Brief description of drawings]

FIG. 1 is a front sectional view of a rotary throttle valve type carburetor having a throttle valve according to the present invention.

FIG. 2 is a perspective view of a throttle valve of the rotary throttle valve type carburetor.

FIG. 3 is a perspective view of another throttle valve of the rotary throttle valve type carburetor.

FIG. 4 is a perspective view of another throttle valve of the rotary throttle valve type carburetor.

FIG. 5 is a perspective view of another throttle valve of the rotary throttle valve type carburetor.

[Explanation of symbols]

A: Fuel metering mechanism 2: Inflow valve 8: Pulsating pressure chamber 8a:
Spring 9: Pump chamber 10: Membrane 11: Fuel pump 1
3: inlet 15: carburetor main body 16: intake passage 24: spring 25: constant pressure fuel chamber 27: shaft 28: lever 2
9: Membrane 30: Atmosphere chamber 30a: Cover 37: Fuel tank 38: Pipe 47: Throttle valve 47a: Shaft part 47b: Throttle hole 49: Intermediate wall body 51: Throttle valve lever 53: Lid plate 54: Spring 55: Needle valve 56:
Fuel nozzle 56a: injection hole 56b: through hole 57: valve chamber 59: jet 63: heat insulating pipe 68: groove 69: groove 70: lightening 72: annular projection 73: annular projection 74: annular projection 7
5: Axial ridge 76: Spiral ridge 80: Annular ridge

Claims (3)

[Claims] 1. A rotary throttle valve type wherein an outer peripheral surface of the throttle valve is provided with a grid-shaped protrusion that contacts the valve chamber of the carburetor main body, and the other portion of the outer peripheral surface is thinned. Vaporizer. 2. An annular ridge that contacts the valve chamber of the carburetor body at the upper and lower ends of the outer peripheral surface of the throttle valve, and an axial ridge that contacts the valve chamber of the carburetor body at the middle portion. A rotary throttle valve type carburetor characterized in that a ridge is provided and the other portion of the outer peripheral surface is thinned. 3. A rotary throttle valve type carburetor, characterized in that spiral throttle grooves are provided on the outer peripheral surface of the throttle valve so as not to come into contact with the valve chamber of the carburetor main body and intersect each other.