JPH0320585B2 - - 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 in particular 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 has a throttle valve connected to an intake passage. 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.

[Conventional technology]

Conventionally, as mentioned above, sliding throttle valve type carburetors are often used in motorcycles, and since they tend to be smaller in size and have higher output, it is desirable to improve the suction efficiency of the carburetor. . 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.

The 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 shaped like an arc, and the side surface facing the air cleaner side is connected to the end of the side surface facing the engine side. This uses a sliding throttle valve formed by a straight part that is perpendicular to the longitudinal axis of the intake passage and a connecting part that connects the straight part. According to this, the groove in the guide section of the sliding throttle valve to the carburetor body can be made extremely small, and this allows the engine to maintain good suction efficiency, making it possible to improve the output. It was made.

In manufacturing such a carburetor, in particular, the engine-side surface of the throttle valve guide cylinder is processed 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 throttle valve guide cylinder is performed by milling, which requires many man-hours and increases manufacturing costs.

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 problems]

The method of manufacturing a sliding throttle valve type carburetor according to the present invention was devised in view of the above-mentioned disadvantages, and the main purpose is to reduce manufacturing costs. A throttle valve guide tube is formed in series to extend across the intake passage and match the shape of the sliding throttle valve, and a circle corresponding to the arc-shaped engine-side facing side surface 7A of the sliding throttle valve of the throttle valve guide tube is formed in series. The arc-shaped engine-side sliding surface and the linear air-cleaner-side sliding surface corresponding to the straight part of the opposite side surface on the air cleaner side are broached, and then the throttle valve guide cylinder that opens at the bottom of the carburetor body is broached. The lower opening is closed with a jet block.

[Effect]

The throttle valve guide cylinder was processed by broaching.

〔Example〕

Hereinafter, an example of a method for manufacturing a sliding throttle valve type carburetor according to the present invention will be explained with reference to the drawings.

Reference numeral 1 denotes a carburetor body through which an intake passage 2 passes, and a throttle valve guide cylinder 3 is connected to the intake passage 2 and opens across the intake passage 2, while a lower recessed portion of the carburetor body 1 and A float chamber 5 is formed by the float chamber main body 4. A float 6 is disposed within the float chamber 5, and this float operates a valve seat disposed at the end of a fuel inflow path (not shown) and a float valve that opens and closes the valve seat. Forms and maintains a constant liquid level.

7 is a sliding throttle valve, which will be explained in more detail with reference to FIG. The sliding throttle valve 7 is formed by an engine side facing side surface 7A (left side in the figure) facing the engine side and an air cleaner side facing side surface 7B facing the air cleaner side. The side surface 7A is formed in an arc shape (semicircular shape with a single radius R).

On the line A-B connecting the arcuate ends A and B of the side surface 7A facing the engine side, or on the engine side from the line A-B (on the left side in the figure), there is a jet inserted into the needle jet described later. Place the center C of the needle 8. More specifically, the center of the jet needle insertion hole 7C into which the jet needle 8 is inserted and held may be placed on the line A-B or closer to the engine than the line A-B.

The air cleaner side facing side surface 7B is connected to the end portions A and B of the engine side facing side surface 7A, and the straight portion 7 is perpendicular to the longitudinal axis XX of the intake passage 2.
D, 7D and a connecting portion 7E that connects the straight portions 7D, 7D, and specifically, the connecting portion 7E is formed in a semicircular shape.

Note that 9 is a needle jet that opens into the intake passage 2, and 10 is a top cover that closes the upper opening of the throttle valve guide cylinder 3. In particular, the carburetor main body 1 is formed as shown in FIGS. 4 and 5.

That is, the throttle valve guide tube 3 matches the shape of the sliding throttle valve 7, is bored perpendicular to the intake passage 2 of the carburetor body 1, and has an upper opening U.
and the lower opening D opens.

Then, an arcuate engine-side sliding surface 3A corresponding to the arcuate engine-side opposing side surface 7A of the sliding throttle valve 7 of the throttle valve guide cylinder 3 and a straight portion of the air cleaner-side opposing side surface 7B of the sliding throttle valve 7. 7D, the linear air cleaner sliding surfaces 3B, 3B corresponding to 7D are broached, and after such broaching, the lower opening D of the throttle valve guide cylinder 3 is closed with a jet block 11. be.

〔Effect of the invention〕

According to the method of manufacturing a sliding throttle valve type carburetor according to the present invention, the following effects are achieved.

Since the throttle valve guide tube is broached with the upper and lower parts open, the dimensional accuracy and machined surface roughness of the engine side sliding surface and the air cleaner side sliding surface of the throttle valve guide tube can be machined with high precision. Therefore, it is possible to control the minute amount of air during 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, we left the air cleaner side sliding surface, especially the connecting part connecting the straight part, in an unprocessed state, so we used broaching. Chips are removed well during the process.
This greatly improves broaching accuracy and tool life.

Since we were able to accurately suppress the straight parts of the sliding throttle valve's side facing the engine side and the side facing the air cleaner side and the front and rear of the sliding throttle valve, we were able to improve the air control performance of the sliding throttle valve. It is something that

[Brief explanation of the drawing]

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 longitudinal cross-sectional view of only the carburetor body after completion of processing, and FIG. 5 is a top plan view of FIG. 4. 1... Carburetor body, 2... Intake path, 3... Throttle valve guide tube, 3A... Engine side sliding surface, 3B... Air cleaner side sliding surface, 7... Sliding throttle valve, 7A
...Side surface facing the engine side, 7B...Side surface facing the air cleaner side, 7D...Straight section, 7E...Connection section,
11...Jet block.

Claims (1)

[Scope of Claims] 1. A throttle valve guide cylinder is connected to the intake passage passing through the carburetor body, and the throttle valve guide cylinder is constituted by a side surface 7A facing the engine side and a side surface 7B facing the air cleaner side. The side surface facing the engine side is formed into an arc shape, and the side surface 7B facing the air cleaner side is the side surface 7B facing the engine side.
A slide formed by straight parts 7D, 7D that are connected to the ends A, B of A and perpendicular to the longitudinal axis XX of the intake passage 2, and a connecting part 7E that connects the straight parts 7D, 7D. A sliding throttle valve type carburetor in which a dynamic throttle valve 7 is disposed; A throttle that is connected to an intake passage 2 passing through the carburetor body 1 and extends across the intake passage 2 to match the shape of the sliding throttle valve. A straight line between an arcuate engine-side sliding surface 3A that forms the valve guide cylinder 3 and corresponds to the arcuate engine-side opposing side surface 7A of the sliding throttle valve 7 of the throttle valve guide cylinder, and an air cleaner-side opposing side surface 7B. Straight air cleaner side sliding surfaces 3B, 3B corresponding to portions 7D, 7D
A method of manufacturing a sliding throttle valve type carburetor, in which the lower opening D of the throttle valve guide tube 3, which opens at the bottom of the carburetor body 1, is closed with a jet block 11.