JPS63243443A - Manufacture of sliding throttle valve type carburetor - Google Patents

Abstract

PURPOSE:To raise the extent of accuracy of finishing as well as to improve the dynamic characteristic of a sliding throttle valve, by setting one side face of a guide cylinder as a guide for a broach cutter and making it machine another side face at the time of broaching the throttle valve guide cylinder to be fitted in the sliding throttle valve combinedly installed in a carburetor body. CONSTITUTION:A sliding throttle valve 6 to be fitted, free of slide motion, in the guide cylinder 3 combinedly installed in a carburetor body 1 so as to be opened to a suction passage 2 is provided with a circular engine side opposed side 6A and an air cleaner side opposed side 6B. At the time of manufacturing a carburetor like this, first an engine side flank 3A of the guide cylinder 3 is formed into small form in similar form as the said flank, forming it by means of casting extraction. Next, a flank 3B of the guide cylinder 3 is set down as a guide for a broach cutter whereby the engine side flank 3A is machined. Afterward, a lower part of the guide cylinder 3 to be pierced through a carburetor body recess 1A is blocked up by a jet block 10.

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 described above, <, f! F-dynamic throttle valve type carburetors are often used in motorcycles, and since they tend to be smaller and more expensive, it is desired to improve the suction efficiency of the carburetor. A vaporizer aiming at improving this suction efficiency was achieved in Japanese Patent Application No. 152940/1983 filed by the applicant of the present invention.

In this case, the sliding throttle valve is constituted by a side surface facing the engine side and a side surface facing the air cleaner side, the side surface facing the engine side is formed into an arc shape, 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 a circular arc shape.

[Problem that the invention seeks to solve]

This conventional method of manufacturing a sliding throttle valve type carburetor has the following problems.

■The throttle valve guide cylinder is processed by milling, which requires many man-hours and increases manufacturing costs.

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

■If the surface roughness obtained by 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 it is necessary to control the cutting tools, etc. It is difficult to manage 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 drawbacks, and the main purpose is to reduce manufacturing costs. and a side surface opposite to the air cleaner side,
The side surface facing the engine side is formed into an arc shape, and the arc-shaped end of the side surface facing the engine side and the end portion of the side surface facing the air cleaner side are each connected by a guide side surface substantially along the longitudinal axis of the intake passage. At the same time, a cleftway is provided at the bottom of the sliding throttle valve from the side opposite to the near cleaner side to the side opposite to the engine side, and the center of the jet needle, which is roughly arranged on the sliding throttle valve, is connected to the end of the side opposite to the air cleaner side to connect the intake air. Located closer to the engine than the line perpendicular to the longitudinal axis of the road,
In a sliding throttle valve type carburetor in which the sliding throttle valve is movably disposed in a throttle valve guide tube provided from the upper part of the carburetor body through a downward concave portion of the carburetor body; The side surface on the cleaner side is molded to have the same shape as the side surface opposite to the air cleaner side of the sliding throttle valve and perpendicular to the longitudinal axis of the intake passage, while the side surface on the engine side of the throttle valve guide cylinder is formed by sliding. The air cleaner side is made similar in shape to the side surface facing the engine side of the throttle valve, and formed by casting perpendicularly to the longitudinal axis of the intake passage.Then, the throttle valve guide cylinder is broached. The side surface on the engine side is broached using the side surface as a guide for a broaching tool, and then the lower part of the throttle valve guide tube that opens in the lower four parts of the carburetor body is closed off with a jet block.

[Effect]

In machining the throttle valve guide cylinder, the side surface on the air cleaner side is used as a guide in broaching, and only the side surface on the engine side is broached.

〔Example〕

Hereinafter, an example of a sliding throttle valve type carburetor which has not yet been invented will be described in the first example. '2.3 This will be explained using Figure 2.3.

Reference numeral 1 denotes a carburetor main body through which an intake passage 2 passes through, and a throttle valve guide cylinder 3 is connected to the intake passage 2 and opens. A float chamber 5 is formed by this. A float F is arranged in the float chamber S,
This float F 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, 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 has an engine side facing side surface 17 facing the first engine side.
A (on the left side in the figure) and an air cleaner side opposing side surface 6B opposite to the air cleaner side, and this engine side opposing side surface 6A is formed in an arc shape (semicircular shape with a single radius R). be done. Then, from the arcuate ends A and B of the engine side facing side surface 8A, the intake passage 2 is
Guide side surface ec, 6 approximately along the longitudinal axis x-X of
c, and the other end C of this guide side surface sc, ec
, D (the side opposite to the opposite side surface 6A on the !j1 side), an air cleaner side opposite side surface 6B is formed. (The width H of the guide side surfaces 8G and 8C is preferably a small width of about 3 millimeters.) Furthermore, the air cleaner side opposing side surface 6B will be described in detail. From the other ends C and D of the guide side surfaces ec and ec, a straight section 1 (D, EID) that is approximately orthogonal to the longitudinal axis x-X of the intake passage 2 and the longitudinal axis X-
x, and is connected to the connecting portion BE that extends from the straight portions fiD and 8D to the air cleaner side (to the right in FIG. 3).

Furthermore, a cutaway 6F is provided at the bottom of the sliding throttle valve 6 that opens into the intake passage 2 to control the intake passage negative pressure that acts on the needle jet, which will be described later. An inclined surface is formed from the opposing side surface 6B toward the engine side opposing side surface 6A.

The longitudinal axis x- of the intake passage 2 of the sliding throttle valve 6
The center K of the jet needle 7 is located on the engine side (on the left side in FIG. 3) from the line CD connecting the ends C and D of the opposite side surface 6B on the air cleaner side. More specifically, the center of the jet needle insertion hole 8G into which the jet needle 7 is inserted and held is located on the line C-D or on the line C-D.
It should be placed closer to the engine.

In addition, 8 is a needle jet opened in the intake passage 2,
This needle jet 8 is immersed below a constant liquid level in the float chamber 5 via a main fuel jet 9.

In particular, the carburetor main body 1 has a structure as shown in FIGS. 4 and 5. That is, the throttle valve guide tube 3 is connected to the intake path 2.
It is formed by casting from the upper part to the lower four parts 1A of the carburetor main body 1 through it, and the cross-sectional shape of the throttle valve guide tube 3 shown in (2) approximately matches the cross-sectional shape of the sliding throttle valve 6. Here, the engine side surface 3 of the throttle valve guide cylinder 3
A and the air cleaner side surface 3B are as follows.

That is, the air cleaner side side surface 3B has the same shape as the air cleaner side opposing side surface GB of the sliding throttle valve 6.

Moreover, it is formed by casting perpendicularly to the longitudinal axis XX of the intake passage 2.

The engine-side side surface 3A is made similar in shape to the engine-side opposing side surface 6A of the sliding throttle valve 6, and has a slight 1, for example, 0.5 mm diameter so as to have a machining allowance for later broaching. It has a small shape of about 5 mm, and is formed perpendicularly to the longitudinal axis x--x of the intake passage 2.

The above-mentioned air cleaner side side surface 3A and the engine side side surface 3A in the direction perpendicular to the longitudinal axis x--X of the intake passage 2 will be explained with reference to the dashed dotted line in the example side view 4. Immediately, the upper core 2OA is extended from the upper opening U of the throttle valve guide cylinder 3 to the lower recess 1^ of the carburetor main body 1, and -
The lower core 20Bly is arranged from the lower recess 1A of the male carburetor main body 1 to the L side core 20A, and the upper core 20A has a surface corresponding to the engine side side surface 3A orthogonal to the intake passage 2. On the other hand, the lower core 20B has an air cleaner side side surface 3B orthogonal to the intake passage 2 formed therein.

The upper core 2OA and the lower core 20B have such a mold structure that the upper core 2OA and the lower core 20B are molded together at the slopes M and N in the throttle valve guide cylinder 3, and the slopes M , N length of intake tract 2゜: hand direction axis +C+a
By pulling out the cores 2OA, 20B at an angle larger than the angle θ relative to Each of the side surfaces 3A and 3B can be formed perpendicular to the longitudinal axis XX of the intake passage 2.

Next, broaching of the throttle valve guide tube 3 will be explained. The broaching tool (not shown) does not have a blade on the side corresponding to the air cleaner side side 3B, but has a blade only on the side corresponding to the engine side side 3A. First, prepare one with
A broaching tool is inserted into the throttle valve guide tube 3, and at this time, the broach is guided by the air cleaner side side surface 3B of the throttle valve guide tube 3 and broaches only the engine side side surface 3A.

Therefore, the broaching process does not involve machining the entire circumferential surface of the throttle valve guide tube 3, and the cutting allowance can be made almost uniform, so it is possible to improve the machinability, and the broaching tool only guides one side. Moreover, since the cutting allowance can be made substantially uniform regardless of the depth of the throttle valve guide cylinder 3, the shape of the throttle valve guide cylinder 3 can be manufactured with extremely high precision.

In addition, when producing broach tools, it was possible to use single-edged blades rather than double-edged tools, which enabled a significant reduction in the cost of the tool.

Furthermore, in the case shown in FIG. 6, only the parts necessary for performance are cut without broaching the entire engine side side surface 3A of the throttle valve guide cylinder 3.

That is, 3A' is an intake passage outer circumferential protrusion that entirely surrounds the intake passage 2, and 3^'' is a protrusion extending along the longitudinal axis X-x of the intake passage 2, and extends in the longitudinal direction of the throttle valve guide cylinder 3. Axial center line Y-Y
3A″' is a central guide protrusion along the longitudinal axis Hx-x of the throttle valve guide cylinder 3, and side guides located on both sides of the longitudinal axis Y-Y of the throttle valve guide cylinder 3. These are the intake path outer peripheral protrusion 3A' and the central guide protrusion 3A.
'', and the side guide f guide protrusion 3A'' are molded to be smaller than the shape of the sliding aperture 66, and the machining allowance for these protrusions is 1 mm or less, which is the life of the tool and machining 1- This is more preferable in terms of surface roughness.

Then, the throttle valve guide cylinder 3 is pressurized in the same manner as above, but in this example, only a limited part of the engine side side surface 3A is machined, so the cutting takt time is further reduced. As a result, additional costs can be further reduced.

〔Effect of the invention〕

As described above, the method for manufacturing a sliding throttle valve type carburetor according to the present invention has the following effects.

The throttle valve guide cylinder has its upper and lower parts open, and the engine side and air cleaner side sides of the throttle valve guide cylinder are formed by casting at right angles to the longitudinal axis of the intake passage. When broaching the guide cylinder, the engine side side surface was broached using the air cleaner side side surface as a guide for the broaching tool, so the engine side side surface can be machined with a nearly constant cutting allowance, and the air cleaner side side surface is used as a guide for the broaching tool. It is extremely accurate and can form the throttle valve guide cylinder at right angles to the H1 intake path), preventing dust,
Furthermore, in broaching, one of the blades is used as a guide, and the other blade is used to form a piece r=f3.

Since the sliding surface has been machined, it is possible to improve workability and reduce the cost of cutting tools, allowing the carburetor body to be manufactured accurately and at low cost.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing an embodiment of the sliding throttle valve type carburetor according to the present invention, FIG. 2 is a plan view of the L section with the top cover of FIG. 1 removed, and FIG. Figure 1 is a detailed explanatory view from the top plane of the sliding throttle valve used, Figure 4 is a vertical sectional view of only the carburetor body after completion of molding, Figure 5 is a top plan view of Figure 4, and Figure 6 The figure is a vertical cross-sectional view taken along the line [-17 in FIG. 4, and FIG. 7 is a vertical cross-sectional view taken along the line ■--■ in FIG. 4. ■91. Carburetor body, 21.9 Intake path, 313. Throttle valve guide tube, 3A, Engine side side, 3A', Air intake path outer peripheral protrusion, 3A'', Center guide protrusion,
3A''', lateral guide protrusion, 3B... air cleaner side surface., 228 Name of the invention Method for manufacturing a sliding throttle valve type vaporizer 3 Relationship with the case of the person making the amendment Patent applicant address Shinjuku 4-chome, Shinjuku-ku, Tokyo [113!17.Q Name Keihin Seiki Seisakusho Co., Ltd. Representative Takeo Iwai 4 Agent 220 Address 2-11-2 Takashima, Nishi-ku, Yokohama Date of amendment order 1 June 30, 2016 6 Column 7 of “Brief explanation of drawings” of the specification subject to amendment Content

Claims (2)

[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 arc-shaped, and the arc-shaped end A of the side surface facing the engine side is formed.
, B and ends C and D of the opposite side surface 6B on the air cleaner side are connected by guide side surfaces 6C and 6C approximately along the longitudinal axis XX of the intake passage 2, respectively, and the sliding throttle valve 6 is A cutaway 6F is provided at the bottom from the air cleaner side opposing side surface 6B to the engine side opposing side surface 6A, and the center K of the jet needle 7 to be placed in the sliding throttle valve 6 is set at the ends C and D of the air cleaner side opposing side surface 6B. The sliding throttle valve 6 is connected from the upper part of the carburetor body 1 to the lower concave portion 1A of the carburetor body 1, and the sliding throttle valve 6 is inserted from the upper part of the carburetor body 1 to the lower recess 1A of the carburetor body 1. In a sliding throttle valve type carburetor which is movably arranged in a throttle valve guide tube 3 which is provided to penetrate the air cleaner side; Same shape as 6B,
The intake passage 2 is formed by casting perpendicularly to the longitudinal axis X-X, and the engine side side surface 3A of the throttle valve guide tube 6 has a similar shape to the engine side opposite side surface 6A of the sliding throttle valve 6. The air cleaner side surface 3B is molded into a small shape and perpendicular to the longitudinal axis X-X of the intake passage 2 by casting, and then the throttle valve guide cylinder 3 is broached. Manufacture of a sliding throttle valve type carburetor by broaching the engine side side surface 3A as a guide, and then closing the lower part of the throttle valve guide tube 3 opening into the lower recess 1A of the carburetor body 1 with a jet block 10. Method. (2) 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 arc-shaped, and the arc-shaped end A of the side surface facing the engine side is formed.
, B and ends C and D of the opposite side surface 6B on the air cleaner side are connected by guide side surfaces 6C and 6C approximately along the longitudinal axis XX of the intake passage 2, respectively, and the sliding throttle valve 6 is A cutaway 6F is provided at the bottom from the air cleaner side opposing side surface 6B to the engine side opposing side surface 6A, and the center K of the jet needle 7 to be placed in the sliding throttle valve 6 is set at the ends C and D of the air cleaner side opposing side surface 6B. The sliding throttle valve 6 is connected from the upper part of the carburetor body 1 to the lower concave portion 1A of the carburetor body 1, and the sliding throttle valve 6 is inserted from the upper part of the carburetor body 1 to the lower recess 1A of the carburetor body 1. In a sliding throttle valve type carburetor which is movably arranged in a throttle valve guide tube 3 which is provided to penetrate the air cleaner side; Same shape as 6B,
The intake passage 2 is formed by casting perpendicularly to the longitudinal axis X-X, and the engine side side surface 3A of the throttle valve guide tube 6 has a similar shape to the engine side opposite side surface 6A of the sliding throttle valve 6. The intake passage outer circumferential protrusion 3A surrounds the intake passage 2 and has a small shape.
, a central guide protrusion 3A that passes through the approximate longitudinal axis XX of the intake passage 2 and extends along the longitudinal axis Y-Y of the throttle valve guide cylinder 6.
'', and side guide protrusions 3A''', 3A''' that pass through the approximate longitudinal axis X-X of the intake passage 2 and are located on both sides of the longitudinal axis Y-Y of the throttle valve guide cylinder 3. , and is formed by casting perpendicular to the longitudinal axis XX of the intake passage 2, and then when broaching the throttle valve guide cylinder 3, the air cleaner side surface 6B is used as a guide for a broaching tool. Broaching the intake passage outer peripheral protrusion 3A', central guide protrusion 3A'', and side guide protrusion 3A'' on the engine side side surface 6B,
Thereafter, the lower part of the throttle valve guide tube 3 which opens into the lower recess 1A of the carburetor main body 1 is closed with a jet block 10, thereby manufacturing a sliding throttle valve type carburetor.