JPS5827082Y2 - Sliding throttle valve type carburetor - Google Patents

Description

[Detailed description of the invention] The present invention relates to a sliding throttle valve type carburetor, that is, a carburetor that uses a sliding valve such as a piston valve as a throttle valve in the intake passage. While the negative pressure on the downstream side of the engine exceeds a certain value, the air-fuel mixture adjusted by the throttle valve is increased while maintaining the appropriate concentration, thereby automatically correcting an excessive decrease in the air-fuel mixture filling efficiency of the engine;
The purpose is to prevent pollution caused by unburned components of exhaust gas.

An embodiment of the present invention will be explained below with reference to the drawings.
A piston type throttle valve 3 is slid onto a throttle valve guide cylinder 2 connected to the upper side of the intake cylinder 1, and its lower part faces an intake passage 4 of the intake cylinder 1.

This throttle valve 3 is connected via a link mechanism 6 to a pulley 5 pivotally supported on the upper part of the throttle valve guide cylinder 2 so as to move up and down as the pulley 5 rotates forward and backward. It is rotated in forward and reverse directions by pulling the wire 7.8.

A float chamber 9 is formed on the lower side of the intake body 1, and a main nozzle 10 that communicates with the oil level inside is opened into the intake passage 4 directly below the throttle valve 3, and the upper end of the jet needle 11 inserted into the main nozzle 10 is opened to the intake passage 4 directly below the throttle valve 3. Attach to throttle valve 3.

A cylindrical portion 3a with an open bottom surface is formed at the lower end of the throttle valve 3, and a ventilation groove 12 is provided on the lower surface of the rear wall, and a piston-shaped valve body 13 for opening and closing the groove is slid into the cylindrical portion 3a.

A negative pressure chamber 15 is formed above the valve body 13 and communicates with the downstream side of the throttle valve 3 via a vent hole 14, and the valve body 13
A return spring 17 is provided that urges the throttle valve 3 toward a lowering limit stopper 16 fixed to the throttle valve 3.

In the figure, reference numeral 18 is an idle stop screw that can adjust the idle opening degree of the throttle valve 3.

Next, to explain the operation of the above embodiment, the valve body 13 is normally held at the lower limit shown in the figure by the resilient force of the return spring 17, and as a result, the opening area of the main nozzle 10 is smaller than that of a conventional carburetor of this type. is adjusted in the same way.

In this state, the engine remains idling, accelerating, and slowly decelerating without excessive negative pressure being generated downstream of the throttle valve 3, and therefore the throttle valve 3 is opened in the same way as in the conventional case. By adjusting the concentration, the concentration and flow rate of the air-fuel mixture generated in the intake passage 4 can be adjusted to adapt to each of the above-mentioned operations of the engine.

However, when the throttle valve 3 is rapidly closed from a high opening to an idle opening in order to rapidly decelerate the engine from a high-output operating state, excessive negative pressure is generated downstream of the throttle valve 3. The pressure is transmitted from the ventilation hole 14 to the negative pressure chamber 15, and the valve body 13 is pulled up against the elastic force of the return spring 17 to open the ventilation groove 1.
2 is opened, the amount of air passing over the main nozzle 10 increases even though the throttle valve 3 is closed to the idle opening, and the amount of oil injected from the main nozzle 10 increases accordingly, which causes the engine to An excessive decrease in the mixture filling efficiency in is corrected.

As described above, according to the present invention, the main nozzle 10 of the throttle valve 3
A ventilation groove 12 is provided on the end face facing the ventilation groove 12, and a valve body 13 capable of opening and closing the ventilation groove 12 is slid onto the throttle valve 3, so that negative pressure of a certain value or more is generated downstream of the throttle valve 3 due to deceleration of the engine. Since the valve element 13 is actuated to open the ventilation groove 12 when the engine suddenly decelerates, the throttle valve 3 closes to the idle opening while the downstream negative pressure of the throttle valve 3 exceeds a certain value. However, by opening the ventilation groove 12 by the valve body 13, the area of the intake passage facing the opening of the main nozzle 10 can be increased and the flow rate of intake air passing therethrough can be increased and corrected. Since the amount of fuel ejected from the main nozzle is appropriately increased in accordance with the increase in the amount of passing air, it is possible to increase the amount of the air-fuel mixture adjusted by the throttle valve 3 while maintaining it at an appropriate concentration from beginning to end. The system can automatically compensate for an excessive decrease in the engine's air-fuel mixture filling efficiency, allowing good combustion of the air-fuel mixture to continue even when the engine suddenly decelerates, thereby preventing contamination by unburned components of the exhaust gas. can be prevented.

Furthermore, when the increased amount of intake air passes near the main nozzle opening in the intake passage, it is sufficiently mixed with the fuel jetted from the main nozzle, so that secondary air can be directly supplied to the downstream side of the throttle valve. Compared to conventional combustion engines, the concentration distribution of the air-fuel mixture that reaches the combustion chamber is more uniform, and the air-fuel mixture can be combusted more stably.

[Brief explanation of the drawing]

The drawing is a longitudinal sectional side view of an embodiment of the present invention. 1... Intake cylinder, 2... Throttle valve guide cylinder,
3... Throttle valve, 4... Intake path, 10.
...-main nozzle, 12... ventilation groove, 13.
...Valve body.

Claims (1)

[Scope of utility model registration request] A throttle valve guide cylinder 2 is connected to one side of the intake body 1 forming an intake passage 4 through which the main nozzle 10 opens, and a throttle valve 3 for opening and closing the intake passage 4 on the main nozzle 10 is slid inside the cylinder 2. In the sliding throttle valve type carburetor, a ventilation groove 12 is provided on the end face of the throttle valve 3 facing the main nozzle 10;
A valve body 13 that can open and close 2 is slid onto the throttle valve 3, and when a negative pressure of a certain value or more is generated on the downstream side of the throttle valve 3 due to deceleration of the engine, the valve body 13 is actuated to close the ventilation groove. 1
A sliding throttle valve type carburetor that opens 2.