JPH02252953A - Manufacture of constant vacuum type carburetor - Google Patents

Abstract

PURPOSE:To facilitate manufacture by constituting a constant vacuum type carburetor through fitting of a negative pressure working valve inside a guide block insertion hole of a carburetor body by means of a guide block, and by forming the guide block suitable for the negative pressure working valve which has a cylindrical venturi forming part. CONSTITUTION:A carburetor main body 1 is constituted by providing an atmospheric chamber recessed part 3 at one side of an intake passage 2 which penetrates the inside of the main body 1 while providing a main fuel boss 4 and a float chamber recessed part 5 at the other side, and a guide block insertion hole 6 is bored from an upper opening of the recessed part 3. A constant vacuum type carburetor is manufactured by inserting negative pressure working valve 20 into the insertion hole 6 through a guide block 7. The negative pressure working valve 20 is composed of a cylindrical venture formation part 20A which forms a venturi V together with the bottom of an intake passage 2, and a plate-shaped guide parts 20B which project outside from the side surface positioned in the longitudinal direction. The guide block 7 has a venturi forming part guide groove 7A and a plate-shaped guide groove 7B is formed an almost similar figure with an outline which connects a contact point of a groove 7A to a corner of a groove 7B.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a constant vacuum carburetor equipped with a negative pressure operated valve that moves up and down in the intake passage by the negative pressure generated in the intake passage upstream of the throttle valve. In particular, the negative pressure operated valve is formed by a venturi forming part and plate-shaped guide parts respectively protruding laterally from the side surfaces along the longitudinal axis of the venturi forming part, and the negative pressure operated valve is The present invention relates to a method of manufacturing a constant vacuum type vaporizer which is slidably guided and held in a vaporizer main body.

[Conventional technology]

A negative pressure operated valve formed by a venturi forming part and plate-shaped guide parts projecting laterally from the side surfaces along the longitudinal axis of the venturi forming part can particularly improve suction efficiency. For this reason, it has been frequently used in recent years.

It is difficult to form a guide groove for slidingly guiding such a negative pressure operated valve, especially a plate-shaped guide groove for guiding a plate-shaped guide portion.
No. 28 was proposed.

This has a central cylindrical part at the upper center, plate-like parts on both sides of the central cylindrical part and below, and a venturi that slides and guides the venturi forming part of the negative pressure operated valve. A guide member in which a forming part guide groove is bored and a plate-shaped guide groove for slidingly guiding a plate-shaped guide part of a negative pressure operated valve in each of the plate-shaped parts; A central cylindrical groove that is bored and opens into the intake passage from the upper opening of the atmospheric chamber recess and has the same shape as the central cylindrical part of the guide member, and an intake passage that extends to the side of the central cylindrical groove and opens from the upper opening of the atmospheric chamber recess. The venturi forming portion of the guide member is provided with a plate-shaped groove having the same shape as the plate-shaped portion of the guide member and a guide groove that extends to approximately the bottom of the carburetor body. A groove, a plate-shaped guide groove, a venturi forming part of a negative pressure operated valve, and a plate-shaped guide part are slidably arranged therein.

[Problem to be solved by the invention]

According to such a conventional method of manufacturing a constant vacuum type vaporizer, the plate-shaped groove, which is formed in the carburetor body and has the same shape as the plate-shaped part of the guide member, has a groove width smaller than that of the central cylindrical groove. In addition, the change in cross-sectional area from the plate-shaped groove to the central cylindrical groove is rapid. This plate-shaped groove is formed at the same time as die-casting of the carburetor body, but since the shape of the carburetor body is complex and the volume of the carburetor body is large compared to the groove volume of the plate-shaped groove, In particular, deformation is likely to occur when forming plate-shaped grooves by casting, and for this reason, when the guide member is inserted into the guide groove, deformation is particularly likely to occur in the plate-shaped guide groove portion of the guide member, which impedes productivity. It is.

[Means to solve problems]

The method for manufacturing a constant vacuum vaporizer according to the present invention has been developed in view of the above-mentioned problems, and in particular, when the guide block is fitted into the carburetor body, the method for manufacturing the constant vacuum type vaporizer can accurately form the plate-shaped guide groove. The purpose of this invention is to obtain a method, and the following steps have been taken to achieve the above object.

That is, it is a constant vacuum type carburetor equipped with a negative pressure operated valve that controls the intake passage by negative pressure generated in the intake passage upstream of the throttle valve; A negative pressure operated valve formed by a venturi forming part and plate-shaped guide parts respectively protruding laterally from the side surfaces along the longitudinal axis of the venturi forming part; A circular venturi forming part guide groove for slidingly guiding the venturi forming part of the pressure-operated valve is bored, and a plate-shaped guide part of the negative pressure operating valve is slidingly guided on both sides of the venturi forming part guide groove. A plate-shaped guide groove is bored, and the outer shape is made larger than the groove diameter of the venturi forming part guide groove made of a circular shape, and in the direction D-D perpendicular to the groove width direction C-C of the plate-shaped guide groove. , longer than the length extending to each end of the plate-shaped guide groove on both sides, and outward from the line connecting the contact point between the groove corner of the plate-shaped guide groove and the circular venturi forming part guide groove. A guide block formed as shown in FIG. This is a method of manufacturing a constant vacuum type vaporizer in which a guide block is fitted into a guide block fitting hole.

〔Example〕

Hereinafter, one embodiment of the method for manufacturing a constant vacuum type vaporizer according to the present invention will be described with reference to the drawings. Figures 1, 2, and 3 show the material of the carburetor body, with Figure 1 being a longitudinal sectional view, Figure 2 being a top plan view of Figure 1, and Figure 3 being the same as Figure 1. It is a longitudinal cross-sectional view taken along the m-■ line.

1 is a carburetor body through which an intake passage 2 passes, an atmospheric chamber recess 3 on one side of the intake passage 2, and a main fuel post 4 and a float chamber recess 5 on the other side of the intake passage 2; , Guide blow from the upper opening of the atmospheric chamber recess 3.

Then, a fitting hole 6 is bored.

The guide blow 2 fitting hole 6 extends from the upper opening of the atmospheric chamber recess 3 to approximately the bottom of the intake passage 2 . Further, the cross-sectional shape of the guide block insertion hole 6 is made to match the shape of the guide block so that the guide block described later is inserted therein.

Here, the negative pressure operated valve 20 adopted in this constant vacuum type vaporizer
This will be explained with reference to FIG.

This negative pressure operated valve 20 includes a cylindrical venturi forming part 2OA that forms a venturi (2) together with the bottom of the intake passage 2;
It is composed of plate-shaped guide parts 20B that protrude outward from the side surfaces along the longitudinal axis direction Y-Y of the venturi forming part 2OA, and furthermore, a section such as a diaphragm is provided in the upper part of the negative pressure operated valve 20. A body 21 is placed.

Next, the guide block 7 disposed in the guide block insertion hole 6 will be explained with reference to FIGS. 4, 5, 6, and 7. 4 is a vertical side view thereof, FIG. 5 is a top plan view of FIG. 4, FIG. 6 is a vertical side view taken along line Vl-VI of FIG. 5, and FIG. 7 is a perspective view.

The guide block 7 is provided with a venturi forming portion guide groove 7A for slidingly guiding the venturi forming portion 2°A of the negative pressure operated valve 20 downward from approximately the upper portion of the center shaft. Specifically, since the venturi forming portion 2OA is cylindrical, the cross-sectional shape of the venturi forming portion guide groove 7A is circular.

Further, plate-shaped guide grooves 7B for slidingly guiding the plate-shaped guide portions 20B of the negative pressure operated valve 20 are bored outward from the venturi forming portion guide grooves 7A, and these plate-shaped guide grooves 7B It penetrates from the upper part of the guide block 7 toward the lower part. (If the plate-shaped guide portion 20B can be slidably guided, it is not necessary to penetrate the venturi forming portion 20A of the negative pressure operated valve 20.)
is the venturi forming part guide groove 7A of the guide block 7
The plate-shaped guide portion 20B is slidably guided by the plate-shaped guide groove 7B of the guide block 7. Furthermore, the guide block 7 has an intake hole 7C having substantially the same shape as the intake passage 2. It is drilled through the guide block 7 from one side 7D to the other side 7E. That is, the guide block 7 is provided with a venturi forming portion guide groove 7A, a plate-shaped guide groove 7B, and an intake hole 7C.
Let's talk about the external shape.

That is, the outer shape of the guide block 7 needs to satisfy the following.

(2) It has a diameter H that is larger than the groove diameter of the circular venturi forming part guide groove 7A.

■Direction D perpendicular to the groove width direction C-C of the plate-shaped guide groove 7B
-D has a length L greater than the length extending to each end of the plate-shaped guide grooves 7B, 7B on both sides.

■A line J- connecting the groove corner J of the plate-shaped guide groove 7B and the contact point of the circular venturi forming part guide groove 7A.
It should be on the outer side.

It is.

FIG. 5 specifically shows an example of the outer shape of the guide block 7 that satisfies the requirements (1), (2), and (3) above. However, although shown in FIG. 5, the shape of the id block 7 is not limited in any way as long as it satisfies the external shape requirements of (1), (2), and (2).

Therefore, the shape of the guide block insertion hole 6 formed in the carburetor main body 1 described above is formed to have a similar shape so that the outer shape of the guide block 7 described above can be press-fitted or inserted.

The guide block 7 formed as described above is inserted into the guide block insertion hole 6 from the atmospheric chamber recess 3 of the carburetor main body 1. This state is shown in FIG. According to this, the carburetor main body l has a venturi forming portion guide groove 7A that slides and guides the venturi forming portion 20A of the negative pressure operated valve 20 and a plate-like plate that slides and guides the plate-shaped guide portion 20B. An intake hole 7C that matches the guide groove 7B and the intake path 2 is formed.

Then, the material of the carburetor main body 1 thus formed is further processed at desired locations, and then various parts as shown in FIG. 9 are assembled into a product. In other words, the carburetor main body 1 has an intake passage 2 passing through it, and a throttle valve on the engine side! 0 is rotatably arranged on a throttle valve shaft 11, and is provided with a bypass hole 12 and a pilot outlet hole 13 corresponding to the throttle valve and connected to a low-speed fuel system (not shown). A float chamber 15 is formed by a float main body 14 disposed corresponding to one side of the main body l. Inside the float chamber 15, a float 16, a valve seat disposed in a fuel inflow path (not shown), and a float valve are arranged, and a constant liquid level T-T is always formed by the cooperation of these elements.

Further, the negative pressure operated valve 20 is slidably disposed in the groove of the guide block 7 from the recess 3 on the atmospheric chamber side of the carburetor main body 1, and in more detail, the venturi forming part 2OA is the venturi forming part 2OA. A plate-shaped guide portion 20B is disposed within the guide groove 7A, and the upper part of the partition body 21 is further closed with a cover 17. Therefore, the atmospheric chamber 18 is formed by the lower part of the partitioning body 21 and the recess 3 on the atmospheric chamber side, and the pressure receiving chamber 18 is formed by the upper part of the partitioning body 21 and the cover 17.

The atmospheric chamber 18 is communicated with the atmosphere via an atmospheric air introduction path (not shown), and the pressure receiving chamber 18 is connected to the negative pressure of the venturi V through a small hole P opened at the bottom of the venturi forming portion 20A of the negative pressure operated valve 20, for example. pressure is introduced. In addition, a needle jet 31 is opened in the venturi V and is connected to a constant liquid level T-T in the float chamber 15 via a main jet 30. The needle 32 is inserted and arranged, and the gap formed by the jet needle 32 and the needle jet 31 is adjusted by raising and lowering the negative pressure operated valve 20, thereby controlling the amount of air-fuel mixture sucked into the intake passage 2. Furthermore, S
is a spring whose one end is engaged with the negative pressure operated valve 20 and the other end is engaged with the cover 17 so as to apply a downward force to the negative pressure operated valve 20.

Further, the plate-shaped guide portion 20B is a venturi forming portion 2O.
It is sufficient that they each protrude laterally from the outer surface of A, for example, they may protrude from an end portion away from the center of the venturi forming portion 2OA.

In addition, when the guide block is molded especially from a synthetic resin material, the angle of removal of the mold when molding the plate-shaped guide groove and the venturi-forming part guide groove can be made extremely small, so the groove is formed almost at right angles to the intake hole. can be cast out.

〔Effect of the invention〕

The method for manufacturing a constant vacuum vaporizer according to the present invention provides the following effects.

That is, the outer shape of the guide block is larger than the groove diameter of the venturi forming part guide groove which is circular, and the plate-shaped guides on both sides are This is because the length is longer than the length reaching each end of the groove, and it is located on the outside of the line connecting the groove corner of the plate-shaped guide groove and the contact point of the circular venturi forming part guide groove. Then, the guide block insertion hole drilled in the carburetor body is also formed to have a similar shape to the guide block's outer shape, and compared to the conventional technology, the guide block insertion hole is made by casting. It will be formed by punching.

According to this, there is no need to cast out a small guide block insertion hole in the carburetor body for the venturi forming part guide groove, such as a plate-shaped guide groove, so the guide block insertion hole can be formed extremely accurately. Therefore, when the guide block is inserted into the guide block insertion hole, deformation of the plate-shaped guide groove of the guide block can be particularly suppressed, and the negative pressure operated valve can be slid and guided very smoothly.

In addition, since the outer shape of the guide block is made outward from the line connecting the contact point between the groove corner of the plate-shaped guide groove and the circular venturi forming part guide groove, the cross-sectional shape of the guide block insertion hole is The fact that there is no sudden change in the value from an extremely small part to a large part makes it easy to manufacture the mold and extends the life of the mold. When the guide block is fitted, the strength of the guide block in the vicinity of the plate-shaped guide groove is increased, so that deformation of the plate-shaped guide groove is particularly suppressed.

In addition, especially when the guide block is made of synthetic resin material by injection molding, even a plate-shaped guide groove with a small groove width can be formed by casting in a direction approximately perpendicular to the intake hole, and the plate of the negative pressure operated valve can be formed by casting. It is possible to reliably slide and guide a shaped guide portion. This is because the angle at which the mold core is pulled out during injection molding of the synthetic resin material can be set to approximately a right angle.

[Brief explanation of drawings]

The figures show an embodiment of the method for manufacturing a constant vacuum type vaporizer according to the present invention, in which Fig. 1 is a longitudinal cross-sectional view of the material of the vaporizer main body, Fig. 2 is a top plan view of Fig. 1, Figure 3 is Figure 1 m-■
4 is a vertical sectional view of the guide block, FIG. 5 is a top plan view of FIG. 4, and FIG. 6 is a vertical sectional view of the guide block.
- A longitudinal side view along the Vl line, Figure 7 is a perspective view of the guide blow 2, Figure 8 is a top plan view showing the guide block fitted into the carburetor body, and Figure 9 is the desired part of the carburetor body. FIG. 10 is a vertical cross-sectional view incorporating the components of FIG. 10, and FIG. 10 is a perspective view of the negative pressure operated valve. 1. Carburetor main body 2. Intake path 3. Atmospheric chamber recess 6. Guide blow 2 fitting hole 7. Guide block 7A. Venturi forming part guide Groove 7B...
Plate guide groove 7C,... Intake hole 2G...
Negative pressure operated valve 2OA, venturi forming part 20B, plate-shaped guide part 21. ,,,Divided body `` Catty 1 No. No. ■ Part 1 ≦ Koshinkinuta

Claims (3)

[Claims] (1) A constant vacuum carburetor equipped with a negative pressure operated valve that controls the intake passage by negative pressure generated in the intake passage upstream of the throttle valve; a negative pressure operated valve formed by a venturi forming part; and plate-shaped guide parts respectively protruding laterally from the side surfaces along the longitudinal axis of the venturi forming part; A circular venturi forming part guide groove for slidingly guiding the venturi forming part of the pressure-operated valve is bored, and a plate-shaped guide part of the negative pressure operating valve is slidingly guided on both sides of the venturi forming part guide groove. A plate-shaped guide groove is bored, and further, the outer shape is made larger than the groove diameter h of the venturi forming part guide groove made of a circular shape, and in the direction D-D perpendicular to the groove width direction C-C of the plate-shaped guide groove. , longer than the length l reaching each end of the plate-shaped guide groove on both sides, and outward from the line connecting the contact point between the groove corner of the plate-shaped guide groove and the circular venturi forming part guide groove. A guide block formed as shown in FIG. A method for manufacturing a constant vacuum type vaporizer by fitting a guide block into a guide block fitting hole. (2) The method for manufacturing a constant vacuum type vaporizer according to claim 1, wherein the guide block is formed by injection molding. (3) The method for manufacturing a constant vacuum type vaporizer according to claim 1, wherein the guide block is injection molded from a synthetic resin material.