JPS63154848A - Small venturi rotation type carburetter - Google Patents

Abstract

PURPOSE:To reduce the size of a venturi and to prevent lowering of an output during full opening low speed running of an engine, by a method wherein a small venturi is rotated by means of the negative pressure of a large venturi, and a suction negative pressure exerted on a main nozzle is controlled. CONSTITUTION:A small venturi 20, to which a main nozzle 18 is opened is situated in a large venturi 14. The small venturi 20 is formed such that a longitudinal axis X-X is rotatable by means of a shaft member 22, and the shaft member 22 is connected to a drive shaft 28 of a diaphragm device 26 through a transmission device 24. A negative pressure chamber 36 of a diaphragm device 26 is connected to an opening 42 formed in the narrowed part of the large venturi 14. This constitution prevents lowering of a negative pressure, exerted on the main nozzle 18, by inclining the small venturi 20 by means of the diaphragm chamber 26 during a full opening low speed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a carburetor for use in a gasoline engine, and more specifically, a single-barrel carburetor with J3 that can rotate a small venturi. Regarding the vaporizer.

[Background of the Invention] Generally, in a carburetor, the diameter of the R narrow portion of the venturi greatly affects the operation of the engine. In other words, if the diameter of the venturi is selected to be small, the velocity of the intake air passing through it will increase, the atomization of gasoline will be better, and the mixing of fuel and air will be promoted.
Fuel will also be economical. However, in this case, the intake efficiency decreases and the maximum output of the engine decreases.

On the other hand, if the bench diameter is selected to be large, the engine's maximum output will increase, but the switching of the mixture from the low-speed system to the main system will be poor, and the throttle valve will be opened fully and the engine will be operated at low speeds. If this happens, the amount of intake air decreases, and the negative intake pressure acting on the main nozzle opening into the venturi decreases, which interferes with engine operation.

[Object of the Invention] In consideration of the above-mentioned problems, the main object of the present invention is to provide a small venturi rotary carburetor that can provide an air-fuel mixture with an appropriate air-fuel ratio to the engine regardless of the operating state of the engine. It is about providing the equipment.

An object of the present invention is to provide a small venturi rotary carburetor that uses the negative pressure of the large venturi to operate the small venturi to control the intake negative pressure acting on the main nozzle.

An object of the present invention is to provide a small venturi rotary carburetor that prevents a decrease in output during full throttle low speed operation of the engine without increasing the size of the venturi.

[Structure of the Invention] Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, only the constituent parts essential to the invention are shown, and the float chamber, fuel passage, and other usual constituent parts are omitted.

As shown in FIG. 1, the small venturi rotary carburetor 10 of the present invention has a choke valve 12 on the air intake side.
A throttle valve 16 is attached to the lower part of the large venturi 14. The small venturi 20 through which the main nozzle 18 opens is disposed inside the large venturi 14 as a normal double venturi.

However, this small venturi 20 is different from a normal one in that the longitudinal axis XX of the small venturi 20 can be rotated inside the large venturi 14 by means of a shaft member 22. Shaft member 22 is connected to one end of a drive shaft 28 of diaphragm device 26 via a suitable linkage or transmission device 24.

The diaphragm device 26 has a well-known structure in which the casing 3o is divided into an atmospheric pressure chamber 34 and a negative pressure chamber 36 by a diaphragm 32, and a spring member 38 is disposed on the negative pressure chamber 36 side of the diaphragm 32. Yes, diaphragm 32
is kept in an equilibrium position at all times. The other end of the drive shaft 28 is roughly connected to the atmospheric pressure chamber 34 side of the diaphragm 32. Negative pressure chamber 36 of diaphragm @26 is connected to passage 4
The opening 42 provided in the narrow part of the large venturi 14 at 0
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[Operation and Effects of the Invention] Since the small venturi rotary carburetor 10 of the present invention is configured as detailed above, when the throttle valve 16 of the carburetor is fully opened and the engine is operated at high speed, In this case, the negative intake pressure of the engine acting on the large venturi 14 is used for the maximum intake air required by the engine, and the intake air is discharged from the opening 42 of the large venturi 14 to the passage 40.
The negative pressure chamber 36 of the diaphragm device 26 is not acted on through the negative pressure chamber 36 of the diaphragm device 26. Thus, the axis X--X of the rotatably mounted small venturi 20 remains aligned with the central longitudinal axis of the carburetor 10, as shown in FIG.

By the way, when the engine is operated at a low speed, the amount of intake air of the engine decreases and the intake pressure of the engine acting on the large venturi 14 increases, unlike when the engine is operated at a full throttle high speed. And this is opening 42, passage 4
0 on the negative pressure chamber 36 of the diaphragm device 26, the diaphragm 32 pushes the spring member 38 and moves. The movement is transmitted to the shaft member 22 via the drive shaft 28 and rotates the small venturi 20 so that its longitudinal axis X--X is inclined with respect to the axis of the carburetor 10.

Due to the above-mentioned action, when the engine is running at high speed, the small venturi 20
Since the venturi is held in an upright position and covered, the projected area of the venturi is large as shown in FIG. 2, but when operating at full throttle and low speed, the projected area becomes small as shown in FIG. 3. Therefore, when the engine is operated at full throttle and at low speed, a drop in the negative pressure acting on the main nozzle 18 is prevented by reducing the projected area of the venturi.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram for explaining the small venturi rotary carburetor of the present invention, Fig. 2 is a schematic diagram showing the projected area of the venturi during high-speed operation, and Fig. 3 is a schematic diagram showing the projected area of the venturi during full-open low-speed operation. It is a schematic diagram showing a projected area. The main reference numbers in the drawings are listed below. 10...S: Shi-Luventuri rotary carburetor 1
4...Large venturi 18...Main nozzle 20...Small venturi 22...Shaft member 26...Diaphragm V device 28... ... Drive shaft 32 ... Diaphragm 36 ... Negative pressure exchange 4G ... Passage 42 ... Passage 4G in 14 parts of venturi
Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] In a single-barrel carburetor comprising a large venturi and a small venturi with a main nozzle opening, a device for mounting the small venturi so as to be able to rotate about the large venturi, and an actuating device for the mounting device. A small venturi rotary carburetor comprising a diaphragm device coupled to the diaphragm device, and a passageway communicating inlet negative pressure acting on the large venturi to the diaphragm device to actuate the diaphragm device.