JPH0456144B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) This invention relates to a carburetor for a gasoline engine.

(Prior art) Recently, as a carburetor for the engine of a car or a motorcycle, Japanese Patent Application Laid-Open No. 60-243355 and
As shown in Japanese Patent No. 59-59758, variable vent lily type carburetors that are equipped with a suction piston that changes the area of the vent lily portion in accordance with the amount of air flowing through the intake passage have come into widespread use. In this type of carburetor, the metering needle that adjusts the amount of gasoline discharged from the main jet is placed opposite the suction piston.
As shown in the latter of the above publications, a needle in which a collar is fixed to the base of the needle and the collar is pressurized by a compression spring and attached to a suction piston is widely used.

(Problem to be Solved by the Invention) However, the conventional metering needle simply had the base of the steel needle press-fitted into the steel collar. Due to repeated engine vibrations and temperature rises, or the vertical movement of the suction piston,
There was a risk that the needle might come off from the collar, and if the needle came off, it would become impossible to measure the fuel and there was a risk that normal operation would not be possible, resulting in an accident.

This invention solves the above-mentioned conventional problems, and aims to provide a highly reliable variable bench lily type carburetor that can prevent the metering needle from coming off the collar.

(Means for Solving the Problems) However, the carburetor of the present invention is a variable vent lily type carburetor equipped with a suction piston that changes the area of the vent lily portion according to the air flow rate in the intake passage. The metering needle is made by inserting the base of the needle made of aluminum into the provided through hole and anodizing the fitted product so that the tip of the base protrudes from the brim. The variable bench lily type carburetor is characterized in that the collar is attached to the tip of the suction piston in a state in which the collar is pressurized by a compression spring in the direction of the suction piston.

In this invention, aluminum or an aluminum alloy can be used as the aluminum material forming the needle. Further, as the material of the brim, aluminum may be used, or steel or other materials other than aluminum may be used.

In this invention, the fitting between the through hole of the collar and the outer diameter of the base of the needle may be a tight fit, but it is most preferable to press fit the base of the needle into the collar as a tight fit.

In addition, in this invention, the anodizing treatment includes:
Although various anodizing treatment methods can be applied, hard anodizing treatment in which an equally hard film is formed using an aqueous sulfuric acid solution at low temperatures is particularly preferred because it has excellent wear resistance.

(Function) In the variable bench lily type vaporizer of this invention, the base of the needle is anodized after being inserted into the through hole drilled in the brim, so there is a small gap between the through hole and the outer diameter of the needle base. The electrolytic solution for anodizing treatment enters the area, and an anodic oxide film is formed on the outer periphery of the needle base at the insertion part and the inner periphery of the through hole of the collar (when the collar is made of aluminum), and grows within the gap. Because it is full, this anodic oxide film tightly and firmly connects the collar and the needle, preventing the needle from slipping out of the collar. Furthermore, the anodic oxide film formed on the portion of the needle base that protrudes from the brim also acts as a stopper and prevents the needle from coming off the brim. Further, the anodized film formed on the needle portion by anodizing treatment improves the wear resistance against sliding contact with the main nozzle. This improvement in wear resistance and the above-mentioned fixing of the needle and collar can be performed at the same time in a single process of anodizing.

(Example) An example of the present invention will be described below with reference to FIGS. 1 and 2.

In the figure, 1 is a carburetor main body, which is attached to an engine (not shown) via an intake pipe. A throttle valve 2 is rotatably attached to the intake passage 1a of the carburetor body 1.
A main nozzle 4 communicating with the float chamber 3 is provided upstream of the float chamber 3 . The suction piston 5, whose tip end face 5a faces the main nozzle 4, is in sliding contact with the piston bore 1b of the carburetor main body and is movable up and down.
A bench lily portion 6 is constituted by the carburetor main body 1 and the carburetor body 1 . The suction piston 5 is constructed by press-fitting a bottomed cylindrical inner cylinder 8, which is slightly shorter than the piston main body 7, into a piston main body 7, and a diaphragm is inserted between the flanges of the piston main body 7 and the inner cylinder 8. The inner peripheral edge of 9 is clamped. The outer peripheral edge of this diaphragm 9 is held by the carburetor main body 1 and the cover 10,
11 is this cover 10, diaphragm 9, and inner circumference 8
Sakshiyonchiyamba was besieged by 12
is a suction spring installed between the cover 10 and the inner circumference 8. 13 is a lower suction hole bored in the piston body 7, and 14 is an upper suction hole bored in the inner cylinder 8. 15 is a metering needle that fits into the main nozzle 4. After press-fitting the base 16a of the needle 16 made of aluminum alloy into a through hole 18 bored in a stepped short cylindrical collar 17 made of aluminum alloy, Hard anodized. Reference numeral 19 indicates an anodized film formed on the outer surface of this press-fit product, and reference numeral 20 indicates the through hole 18 and the base 16.
This is an anodic oxide film formed within the gap between a. This metering needle 15 has a short cylindrical guide tube 2 that protrudes from the inner surface of the piston body 7.
The collar 17 is fitted into the inner cylinder 1 with a gap, and the spring force of the compression spring 22 inserted between the collar 17 and the inner cylinder 8 applies the collar 17 in the direction toward the distal end surface 5a of the suction piston. It is attached to the tip of the suction piston 5 in a compressed state.

In the variable bench lily type carburetor 23 having the above configuration, when the throttle valve 2 is opened, the amount of air taken into the engine increases, and a negative pressure is generated in the vent lily portion 6 according to the air flow rate. Fuel in the float chamber 3 is metered by a main nozzle 4 and a metering needle 15, and is sucked out to a bench lily part 6. On the other hand, the suction chamber 11 communicates with the bench lily portion 6 via an upper suction hole 14 and a lower suction hole 13, and its internal pressure is equal to the negative pressure generated in the bench lily portion 6. When the suction chamber 11 becomes negative pressure, an upward force is generated on the suction piston 5 due to the pressure difference between the upper and lower sides of the diaphragm 9, and the suction piston 5 is moved at a position where this force and the downward biasing force of the suction spring 12 are balanced. Piston 5 stops. When the amount of intake air is large, the negative pressure generated in the bench lily section 6 becomes high, the air in the suction chamber 11 flows out to the bench lily section 6 through both suction holes 13 and 14, and the suction piston 5 moves upward. do. Conversely, when the amount of intake air decreases, the negative pressure generated in the bench lily portion 6 becomes smaller, the internal pressure of the suction chamber 11 becomes smaller, and the suction piston 5 moves upward. The metering needle 15 held by the suction piston 5, which repeats the above-described vertical movement, measures the fuel from the main nozzle 4 while moving up and down together with the suction piston 5. The collar 17 is held in pressure contact with the bottom of the guide cylinder 21 by the spring force of the compression spring 22, and the needle 16 supports the base 16a by the collar 17.
In addition to the adhesion force due to the press-fitting of the needle 16 and the collar 17, due to the adhesion force of the anodic oxide film 20 formed in the gap in the through hole 18, the needle 16 and the collar 17 are integrated with a strong force, which prevents repeated vibrations and temperature rises. The needle 16 is prevented from falling off the collar 17 even in response to external forces caused by sliding contact with the main nozzle 4. Further, the anodic oxide film 19 formed on the portion of the base portion 16a that protrudes from the flange 17 also has the function of preventing the needle 16 from falling off from the flange 17.

Metering needle 15 with the above configuration (however, diameter of needle base 16a: 2.5 mm, total thickness of collar 17: 2.7 mm, film thickness of anodic oxide film 19: 15 μm)
When the pulling force required to pull out the needle 16 from the collar 17 was actually measured, the pulling force was
100Kg, whereas the pullout force of a conventional product that was only press-fitted and not anodized was 40Kg.

The present invention is not limited to the above-mentioned embodiments; for example, the suction piston 5 may have a structure without the inner cylinder 8, in which case the compression spring 2
The upper end of the guide tube 2 may be held by a cap or the like screwed into the guide tube 21. Further, the collar 17 may be a single perforated disc without a stepped portion.

Further, the present invention can also be applied to a variable bench lily type carburetor that does not use a diaphragm.

(Effects of the Invention) As explained above, according to the present invention, the needle of the metering nozzle can be attached to the flange due to the anodic oxide film formed on the gap between the fitting part of the needle and the flange and on the part of the needle base protruding from the flange. In addition to reliably preventing the needle from coming off, the anodic oxide film also improves the abrasion resistance of the needle, resulting in a highly reliable variable bench lily type carburetor.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a variable bench lily type carburetor showing an embodiment of the present invention, and FIG. 2 is a partially enlarged vertical cross-sectional view of the metering nozzle shown in FIG. 1. DESCRIPTION OF SYMBOLS 1... Carburetor main body, 1a... Intake path, 4... Main nozzle, 5... Suction piston, 5a... Tip surface,
6... Bench lily part, 15... Metering needle, 16... Needle, 16a... Base, 17... Brim, 18... Through hole, 19... Anodized film, 20...
Anodic oxide film, 22...compression spring, 23...variable bench lily type carburetor.

Claims (1)

[Claims] 1. In a variable bench lily type carburetor equipped with a suction piston that changes the area of the bench lily portion according to the air flow rate in the intake passage, the base of an aluminum needle is inserted into a through hole drilled in the brim to open the base. A metering needle, which is a fitted part whose tip protrudes from the flange and is anodized, is inserted into the suction piston while the flange is pressurized by a compression spring in a direction toward the tip surface of the suction piston. A variable bench lily type carburetor characterized by being attached to the tip of the piston.