JPH0545786B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a carburetor that adjusts and controls the amount and concentration of air-fuel mixture supplied to an engine, and particularly relates to a carburetor that adjusts and controls the amount and concentration of air-fuel mixture supplied to an engine. This invention relates to a method of manufacturing a sliding throttle valve type carburetor movably disposed within a guide cylinder, and is often used as a carburetor for motorcycle engines.

[Prior Art] As mentioned above, sliding throttle valve type carburetors have been commonly used in motorcycles, and since they tend to be smaller and have higher output, it is important to improve the suction efficiency of the carburetor. It is desired. A vaporizer aimed at improving this inhalation efficiency was achieved in Japanese Patent Application No. 152940/1983 filed by the applicant of the present invention.

This is a sliding throttle valve composed of at least a side surface facing the engine side and a side surface facing the air cleaner side, and the cross-sectional shape of the side surface facing the engine side of the sliding throttle valve described above is arc-shaped. It is. According to this, the suction efficiency of the engine could be maintained well, and the output could be improved.

The manufacture of such a carburetor, particularly the machining of the engine-side guide cylinder surface of the throttle valve guide cylinder that slidably guides and holds the sliding throttle valve, is carried out by milling because it has an arcuate shape.

[Problems to be Solved by the Invention] This conventional method for manufacturing a sliding throttle valve type carburetor has the following problems.

Machining of the inner cylinder of the throttle valve is performed by milling, which requires many man-hours and increases manufacturing costs.

According to the milling process, since the process is always performed using a rotating cutting tool, it is difficult to expect an improvement in precision, especially near the relatively narrow straight section where the engine-side guide cylinder surface and the air cleaner-side guide cylinder surface intersect. This is because the diameter of the bearing portion that holds the cutting tool is small and cannot maintain high rigidity.

If the surface roughness obtained through machining changes, the sliding resistance and wear resistance of the sliding throttle valve will change significantly. Therefore, it is necessary to obtain a uniform surface roughness, and cutting tool management etc. It is difficult to control cutting conditions.

[Means for Solving the Problems] The method for manufacturing a sliding throttle valve type carburetor according to the present invention has been developed in view of the above-mentioned disadvantages, and its main purpose is to reduce manufacturing costs.
A sliding throttle valve is configured with a side surface facing the engine side and a side surface facing the air cleaner side, the side surface facing the engine side is arc-shaped, and the sliding throttle valve is movable into a throttle valve guide cylinder provided in the carburetor body. In the sliding throttle valve type carburetor disposed in the carburetor body, the throttle valve guide tube formed in the carburetor body is approximately aligned with the cross-sectional shape of the sliding throttle valve, and the throttle valve guide tube is connected from the upper part of the throttle valve guide tube to the lower concave portion of the carburetor body. 1A, and is formed by casting and formed on the engine side guide cylinder surface of the throttle valve guide cylinder, and includes an intake path outer periphery sliding protrusion that surrounds the entire outer periphery of the intake path that opens to the engine side guide cylinder surface, and an intake path abbreviation. A central sliding protrusion passing through the center and extending vertically along the longitudinal axis Y-Y of the throttle valve guide cylinder, and a longitudinal axis of the throttle valve guide surface near both ends of the engine side guide cylinder surface. Side sliding protrusions extending vertically along the core line Y-Y are provided, each of the sliding protrusions is broached, and then a lower opening penetrating the lower recess of the carburetor body 1 is formed into a jet block. It was blocked.

[Function] The processing of the throttle valve guide cylinder was performed by broaching, and the broaching process was also used to control the air on the engine side guide cylinder surface formed on the throttle valve guide cylinder and the guide control of the sliding throttle valve. Only the sliding protrusions necessary for this purpose are processed, and the remaining parts are left unprocessed.

[Example] Hereinafter, an example of the method for manufacturing a sliding throttle valve type carburetor according to the present invention will be described with reference to FIGS. 1, 2, and 3.

Reference numeral 1 denotes a carburetor main body through which an intake passage 2 passes, and a throttle valve guide cylinder 3 that is connected to the intake passage 2 and slidably holds a sliding throttle valve, which will be described later, opens upward. , on the other hand, the lower recess 1A of the carburetor main body 1
A float chamber 5 is formed by the float chamber main body 4 and the float chamber body 4 .

A float F is arranged in the float chamber 5, and this float F
A valve seat (not shown) disposed at the end of the fuel inflow path and a float valve that opens and closes the valve seat are operated by the operator, thereby forming and maintaining a constant liquid level in the float chamber 5. 6 is a sliding throttle valve, which will be explained in more detail with reference to FIG.

The sliding throttle valve 6 is connected to at least an engine (not shown).
It is formed by an engine-side opposing side surface 6A (on the left side in FIG. 3) facing the engine and an air cleaner-side opposing side surface 6B facing the air cleaner (not shown). This engine-side opposing side surface 6A is formed in an arc shape (semicircular shape with a single radius R). The air cleaner side facing side surface 6B connects both ends of the engine side facing side surface 6A in a desired shape.

A jet needle 7 is mounted at the bottom of the sliding throttle valve 6, and this jet needle 7 is inserted into a needle jet 8 opening into the intake channel 2, and this needle jet 8 carries a main fuel jet 9. The float is immersed under a constant liquid level in the float chamber 5 through the float chamber 5.

Figure 1 shows the above-mentioned sliding throttle valve 6 in the carburetor main body 1.
FIG. 2 is a longitudinal cross-sectional view showing a state in which the throttle valve guide cylinder 3 is disposed, and FIG. 2 is a top plan view of FIG. 1 with the top T removed.

According to the present invention, the carburetor body 1 is formed as follows.

The throttle valve guide tube 3 of the carburetor body 1 includes an engine side guide tube surface 3A corresponding to the engine side opposing side surface 6A of the sliding throttle valve 6, and an air cleaner side guide tube surface 3B corresponding to the air cleaner side opposing side surface 6B. This throttle valve guide cylinder 3 penetrates from the upper part 1B of the carburetor main body 1 toward the lower recessed part 1A. Specifically, it is formed by casting during injection molding of the carburetor main body 1.

Then, the engine side guide cylinder surface 3A of the throttle valve guide cylinder 3
The following sliding protrusions are formed on.

That is, 3C is an intake passage outer peripheral sliding protrusion that surrounds the entire outer periphery of the intake passage 2 that opens to the engine side guide cylinder surface 3A, and in this example, since the intake passage 2 has a round shape, it has a band-shaped round shape. . (Indicated by dashed-dotted hatching in FIG. 6.) 3D is a central sliding protrusion that passes approximately through the center of the intake passage 2 and extends vertically along the longitudinal axis Y-Y of the throttle valve guide cylinder 3. It extends upward from the upper end of the intake passage 2 and extends downward from the lower end of the intake passage 2. (Indicated by double-dashed line hatching in FIG. 6.) 3E is located near both ends of the engine side guide cylinder surface 3A, and extends vertically along the longitudinal axis Y-Y of the throttle valve guide cylinder 3. These are extending lateral sliding protrusions, which are formed laterally from the center of the intake passage 2 in FIG. (Indicated by dotted hatching in FIG. 6).

And the above-mentioned intake duct outer peripheral sliding protrusion 3C,
The central sliding protrusion 3D and the side sliding protrusions 3E are formed to be smaller than the outer dimensions of the sliding throttle valve 6, and the remaining portions of the throttle valve guide tube 3 other than the sliding protrusions 3E are slidable. It is molded larger than the outer dimensions of the throttle valve 6.

Next, to describe the manufacturing method, a broach that matches the cross-sectional shape of the sliding throttle valve 6 is inserted into the lower recess 1A from the upper opening of the upper part 1B of the throttle valve guide cylinder 3.
This is processed by inserting it toward the throttle valve guide cylinder 3, thereby forming the intake passage outer circumferential sliding protrusion 3C, the central sliding protrusion 3D, and the side sliding protrusions. It processes 3E.

The cutting allowance for each of these sliding protrusions 3C, 3D, and 3E is 1 mm or less, which is the life of the cutting tool.
This is more preferable in terms of machined surface roughness. Through this processing, the throttle valve guide tube 3 that matches the sliding throttle valve 6 can be formed accurately.

Next, insert this downward recess 1A into the jet block 1.
It closes at 0. Therefore, in particular, the engine-side facing side surface 6A of the sliding throttle valve 6 and the engine-side guide cylinder surface 3A of the throttle valve guide cylinder 3 can be reliably aligned, so that the fully closed air of the sliding throttle valve 6 can be minimized. This makes it possible to control the carburetor, making it particularly suitable as a carburetor for two-stroke engines.

[Effects of the Invention] The method for manufacturing a sliding throttle valve type carburetor according to the present invention provides the following effects.

Since the throttle valve guide cylinder is broached with the upper and lower parts open, the dimensional accuracy and machined surface roughness of the engine side guide cylinder surface and the air cleaner side guide cylinder surface of the throttle valve guide cylinder can be machined with high precision. At the same time, it is possible to control the minute amount of air in the lowest idling operation of the engine and to improve the dynamic characteristics of the sliding throttle valve.

When machining the throttle valve guide cylinder, instead of machining the entire circumference of the throttle valve guide cylinder, only the parts that particularly affect the complete closing of the air were machined, which facilitates removal of chips during broaching. This was done to improve broaching accuracy and greatly extend the life of the cutting tool.

Since we were able to accurately suppress the side surface of the sliding throttle valve facing the engine side, the side surface facing the air cleaner side, and the front and back of the sliding throttle valve, we were able to improve the air control performance of the sliding throttle valve. be.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the method for manufacturing a sliding throttle valve type carburetor according to the present invention, FIG. 2 is a top plan view of FIG. 1 with the top cover removed, and FIG. Fig. 1 is a detailed explanatory view from the top plane of the sliding throttle valve used, Fig. 4 is a vertical sectional view of only the carburetor main body, Fig. 5 is a top plan view of Fig. 4, and Fig. 6 is a detailed explanatory view of the It is a longitudinal cross-sectional view taken along the - line in the figure. 1... Carburetor main body, 2... Intake path, 3... Throttle valve guide cylinder, 3A... Engine side guide cylinder surface, 3C... Intake path outer periphery sliding protrusion, 3D... Center sliding protrusion, 3E
...Side sliding protrusion, 6...Sliding throttle valve, 6A...
Side surface opposite to the engine side, 6B...Side surface opposite to the air cleaner side, 10...Jet block.

Claims (1)

[Claims] 1. The sliding throttle valve 6 is constituted by a side surface 6A facing the engine side and a side surface 6B facing the air cleaner side, the side surface facing the engine side is shaped like an arc, and the sliding throttle valve 6 is connected to the carburetor main body 1. In a sliding throttle valve type carburetor which is movably disposed within a throttle valve guide tube 3 provided in the carburetor body 1, the throttle valve guide tube 3 formed in the carburetor body 1 is approximately aligned with the cross-sectional shape of the sliding throttle valve. from the upper part 1B of the throttle valve chamber cylinder 3 to the lower concave part 1A of the carburetor main body 1.
The engine-side guide cylinder surface 3A of the throttle valve guide cylinder 3 is formed by casting through the engine-side guide cylinder surface 3A.
An intake passage outer periphery sliding protrusion 3C that surrounds the entire outer periphery of the intake passage 2 that opens at A, and passes through the approximate center of the intake passage 2 and extends up and down along the longitudinal axis Y-Y of the throttle valve guide cylinder 3. A throttle valve guide surface 3 is provided near both ends of the center sliding protrusion 3D extending in the direction and the engine side guide cylinder surface 3A.
lateral sliding protrusions 3E extending in the vertical direction along the longitudinal axis Y-Y, each of the sliding protrusions 3
A method of manufacturing a sliding throttle valve type carburetor, which comprises broaching parts C, 3D, and 3E, and then closing a lower opening penetrating the lower recess 1A of the carburetor body 1 with a jet block 10.