JPH07107377B2 - Sliding throttle valve type carburetor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a vaporizer for controlling the amount and concentration of an air-fuel mixture supplied to an engine, and particularly to a throttle valve connected to an intake passage of a vaporizer body. The present invention relates to a sliding throttle valve type carburetor in which a throttle valve for opening and closing an intake passage is slidably arranged in a guide cylinder.

[Conventional technology]

Conventionally, such a sliding throttle valve type carburetor has been constructed such that a bypass hole connected to a low speed fuel passage is directly formed in the carburetor main body in an intake passage corresponding to a bottom portion of the throttle valve on the engine side. In another, a jet block provided with a venturi portion is fitted and a bypass hole connected to the low speed fuel passage is bored in the jet block.

[Problems to be solved by the invention]

According to the former, the bypass hole is formed directly in the carburetor body, and the diameter of the bypass hole is relatively small (for example, 0.6
Mm), processing defects may occur during the processing of the bypass hole, which causes the entire carburetor body to be scrapped, resulting in an increase in damage costs.
The diameter of the bypass hole changes variously depending on the engine compatibility test, which may cause a difference in the diameter of the bypass hole during machining of the carburetor body. Since it opens at the bottom, it is difficult to confirm, which is not preferable for inventory control and quality control. Also, burrs are generated by the cutting tool when the bypass hole is processed, but the deburring workability is poor because it is located at the center of the carburetor body.

On the other hand, according to the latter, a jet block provided with a venturi section requires a tight surface having a relatively long distance on the side orthogonal to the intake passage.The bottom surface of the carburetor body corresponding to the jet block and the jet block is required. It is necessary to provide each with a flat surface and fasten them together.
Since the work for processing and fastening the flat surface is increased and the flat surface is large, a packing material is required to secure airtightness, resulting in high manufacturing cost. Furthermore, since such a jet block has a venturi portion, it requires a die-casting mold, which is not preferable because the die cost is large.

[Means for solving problems]

The sliding throttle valve type carburetor according to the present invention is made in view of the above-mentioned problems, and has an excellent workability of a bypass hole, and is to provide an inexpensive head vaporizer with high productivity. According to the invention, it comprises a cylindrical collar portion, a fuel suction nozzle projecting from the upper surface of the cylindrical collar portion, and an air supply nozzle projecting from the lower surface of the cylindrical collar portion and forming an air hole. The flange and the air supply nozzle have through holes penetrating them, and the cylindrical flange has a bypass hole from the upper surface to the lower surface to form a main fuel nozzle. Is a cylindrical collar portion fitting hole from the intake passage side, a locking step portion connected to the bottom of the cylindrical collar portion fitting hole, and an air supply nozzle fitting hole connected to the locking step portion and having a smaller diameter than the cylindrical collar portion fitting hole. The low-speed fuel is connected to the low-speed fuel passage, and the low-speed fuel is sequentially drilled. By opening a confounding path and arranging a bypass hole drilled in the cylindrical flange of the main fuel nozzle corresponding to the low speed fuel communication path, it also corresponds to an air introduction path that allows the air hole of the fuel nozzle to be drilled in the carburetor body. Then, the cylindrical flange portion of the main fuel nozzle is fitted in the cylindrical flange fitting hole, and the air supply nozzle is fitted in the air supply nozzle fitting hole.

[Action]

By inserting the cylindrical collar portion and the air supply nozzle of the main fuel nozzle into the collar portion fitting hole and the air supply nozzle fitting hole, the main air is supplied from the air introduction passage to the outside of the needle jet and the bypass hole is introduced into the intake passage. A low-speed fuel can be supplied, and further, the main fuel in which the main air is mixed with the fuel sucked from the needle jet into the intake passage from the fuel suction nozzle is supplied.

〔Example〕

An embodiment of the sliding throttle valve type carburetor according to the present invention will be described below with reference to the drawings.

Reference numeral 1 denotes a carburetor main body having an intake passage 2 penetrating the inside thereof, and a throttle valve guide cylinder 3 is continuously provided above an intermediate portion of the intake passage 2. On the other hand, a float chamber body 4 is disposed below the carburetor body 1, and a float chamber 5 is formed by these, and a float 6 disposed inside the float chamber 5 and a valve seat (not shown) A constant liquid surface is always formed on. A throttle valve 7 that opens and closes the intake passage 2 is slidably disposed in the throttle valve guide cylinder 3, and a needle jet 8 that opens to the intake passage 2 is inserted into the lower portion of the throttle valve 7. The jet needle 9 is held.

Then, the needle jet 8 is supplied with the fuel measured by the main jet 10 which is immersed below the constant liquid surface of the float chamber 5. On the other hand, the low-speed fuel is supplied to the low-speed fuel passage 12 through the low-speed fuel jet 11 that is submerged below the constant liquid level in the float chamber 5. Further, a spring 14 that constantly urges a force in the closing direction on the throttle valve 7 is contracted between the top 13 arranged at the upper part of the throttle valve guide cylinder 3 and the throttle valve 7.

The above is a conventionally known sliding throttle valve type carburetor, and the sliding throttle valve type carburetor according to the present invention for achieving the above-mentioned purpose has the following structure.

That is, the main fuel nozzle 15 is a cylindrical collar part having a cylindrical shape.
15A, a fuel suction nozzle 15B projecting from the upper surface A of the cylindrical collar portion 15A, an air supply nozzle 15C projecting from the lower surface B of the cylindrical collar portion 15A, a cylindrical collar portion 15A, and a fuel suction nozzle 15
The B and the air supply nozzle 15C are provided with a through hole 15D penetrating them. Further, a bypass hole 15E is bored from the upper surface A to the lower surface B of the cylindrical collar portion 15A, and an air hole 15F penetrating from the outer surface of the nozzle to the through hole 15D is bored in the air supply nozzle 15C.

On the other hand, the intake passage 2 corresponding to the bottom of the throttle valve 7 is provided with a cylindrical flange fitting hole 16 into which the cylindrical flange 15A of the main fuel nozzle 15 is fitted, and at the bottom of the cylindrical flange fitting hole 16. A locking step portion 17 is provided, and an air supply nozzle fitting hole 18 having a smaller diameter than the cylindrical flange fitting hole 16 is bored from the inside of the locking step portion 17. Then, a low speed fuel communication path 19 continuous with the low speed fuel path 12 opens in a part of the locking step portion 17.

Next, the assembling of the main fuel nozzle 15 to the carburetor body 1 will be described. First, the bypass hole 15E of the cylindrical flange portion 15A of the main fuel nozzle 15 is made to correspond to the low-speed fuel communication path 19 opening to the locking step portion 17, and the cylindrical flange portion 15A is inserted into the cylindrical flange portion insertion hole 16
To simultaneously fit the air supply nozzle 15C into the air supply nozzle fitting hole 18, and according to this, the cylindrical collar portion 15A
The lower surface B of the cylindrical collar portion 15A is arranged on the locking step portion 17 in the cylindrical collar portion fitting hole 16.

In such a state, the bypass hole 15E of the cylindrical collar portion 15A is connected only to the low speed fuel communication passage 19, while the air supply nozzle 15C is connected.
The air hole 15F of the air intake passage 21 connected to the air jet 20
Further, the fuel suction nozzle 15B projects into the intake passage 2 and the needle jet 9 projects into the through hole 15D of the main fuel nozzle 15.

According to such a sliding throttle valve type carburetor, the air controlled by the air jet 20 is supplied to the air supply nozzle 15C via the air introduction passage 21, and this air is supplied to the outside of the needle jet 8 to form the needle. Fuel suction nozzle 15B mixed with fuel controlled by jet 8 and jet needle 9
It is sucked into the intake passage 2 and used for medium-high speed operation of the engine.

On the other hand, the low-speed fuel restricted by the low-speed fuel jet 11 passes through the low-speed fuel passage 12 and the low-speed fuel communication passage 19 and the bypass hole 15
After being supplied to E, it is sucked into the intake passage 2 and used for low speed operation of the engine. Further, particularly, the fuel supplied through the low-speed fuel passage 12 is reliably sealed by the outer circumference of the cylindrical collar portion 15A, the cylindrical collar portion fitting hole 16, the lower surface B of the cylindrical collar portion 15A and the locking step portion 17. Therefore, there is no fear that low-speed fuel will be sucked into the intake passage 2 through the outside of the bypass hole 15E,
On the other hand, the air from the air introduction passage 21 is supplied into the through hole 15D of the main fuel nozzle 15 only through the air hole 15F, and is reliably sealed by the outer circumference of the air supply nozzle 15C and the air supply nozzle fitting hole 18. However, no special sealing member is required. Further, when the bypass hole 15E has a very small diameter of about 0.4 mm in the conformance test, it is possible to make it possible by reducing the thickness of the cylindrical flange portion 15A.

〔The invention's effect〕

 The sliding throttle valve type carburetor according to the present invention has the following effects.

The bypass hole is bored in the cylindrical flange of the main fuel nozzle, and the main fuel nozzle is fitted into each fitting hole of the carburetor body so that the bypass hole is connected to the low-speed fuel communication path connected to the low-speed fuel passage. When processing a bypass hole, it is not necessary to dispose of the carburetor body simply by discarding the main fuel nozzle when a processing failure occurs, so the processing damage cost for defective bypass hole processing is lost. Can be reduced.

As a result of the conformity test to the engine, when the bypass hole diameter difference occurs, the main fuel nozzle can be managed according to the hole diameter difference, and the management of the bypass hole diameter difference of the large carburetor body becomes unnecessary. Further, since the hole diameter is formed in the cylindrical collar portion, it is extremely easy to visually control the hole diameter, which is preferable for inventory control and quality control.

After the bypass hole is machined, burrs are generated at the entrance and the exit of the hole, but since the upper and lower surfaces of the cylindrical flange are open, the deburring action becomes easy, which is preferable for quality control.

The bypass hole diameter is determined by the engine compatibility test, and the hole diameter may be set to 0.6 mm or less.In such a case, fine drilling can be performed by changing (decreasing) the wall thickness of the cylindrical collar portion. It can be made easy and the degree of freedom in manufacturing the carburetor can be improved.

By making the main fuel nozzle, especially the flange and the air supply nozzle, cylindrical, a relatively large flat surface such as that which is orthogonal to the intake passage like a conventional jet block becomes unnecessary,
Moreover, since the fitting is carried out by the outer diameter of the cylindrical collar portion, the lower surface and the outer diameter of the air supply nozzle, the airtightness between the main fuel nozzle and each hole can be maintained without using a sealing member.

Since all outer diameters of the main fuel nozzle can be cut by a lathe, a die for die casting such as a conventional jet block having a Venturi portion is not required and the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 shows an embodiment of a sliding throttle valve type carburetor according to the present invention. FIG. 1 is a longitudinal sectional view and FIG. 2 is FIG. 1 II-II.
FIG. 3 is a perspective view of the main fuel nozzle, and FIG. 15 …… Main fuel nozzle, 15A …… Cylinder collar, 15B …… Fuel suction nozzle, 15C …… Air supply nozzle, 15D …… Through hole, 15
E ... Bypass hole, 15F ... Air hole, 16 ... Cylindrical flange fitting hole, 17 ... Locking step part, 18 ... Air supply nozzle fitting hole, 19
...... Low speed fuel connection path.

Claims (1)

[Claims] 1. A throttle valve guide cylinder is provided in series with an intake passage penetrating a carburetor main body, and the intake passage is opened and closed in the throttle valve guide cylinder and inserted into a needle jet opening to the intake passage. In a sliding throttle valve type carburetor in which a throttle valve holding a jet needle is arranged; a cylindrical collar portion 15A, a fuel suction nozzle 15B protruding from an upper surface A of the cylindrical collar portion 15A, and a lower surface B of the cylindrical collar portion 15A. It further comprises an air supply nozzle 15C projecting more and forming an air hole 15F, the fuel suction nozzle 15B, a cylindrical collar portion 15A, an air supply nozzle 15
In addition to forming a through hole 15D that penetrates them in C,
Bypass holes 15E extending from the upper surface A to the lower surface B are formed in the cylindrical collar portion 15A to form a main fuel nozzle 15, while the carburetor body 1 is provided with a cylindrical collar portion fitting hole 16 from the intake passage 2 side. A locking step portion 17 connected to the bottom of the cylindrical flange fitting hole 16 and an air supply nozzle fitting hole 18 connected to the locking step portion 17 and having a diameter smaller than that of the cylindrical flange fitting hole 16 are sequentially formed and the engagement is performed. A low speed fuel communication path 19 connected to the low speed fuel passage 12 is opened in the stop portion 17, and a bypass hole 15E formed in the cylindrical collar portion 15A of the main fuel nozzle 15 is arranged corresponding to the low speed fuel communication path 19. In addition, the air introduction path 2 for making the air hole 15F of the fuel nozzle 15 in the carburetor main body 1
The sliding throttle valve is arranged corresponding to 1 and then the cylindrical flange portion 15A of the main fuel nozzle 15 is fitted in the cylindrical flange portion fitting hole 16 and the air supply nozzle 15C is fitted in the air supply nozzle fitting hole 18. Type vaporizer.