JPS6136762Y2 - - Google Patents

Description

[Detailed description of the invention] This invention forms a cylinder-shaped valve chamber that bypasses the throttle valve and crosses the bypass connected to the intake passage, and a starting fuel nozzle is installed on one end surface of this valve chamber. The present invention relates to a starting device for a carburetor, in which a piston-type starting valve that opens and can open and close the bypass and starting fuel nozzle is accommodated in the valve chamber.

First, the general structure of such a starting device will be explained with reference to FIG.

Reference numeral 1 denotes a carburetor main body having a horizontal intake passage 2, and a throttle valve guide cylinder 3 on the upper side across the intake passage 2.
However, a float chamber 4 is also formed on the lower side. A piston-type throttle valve 5 that moves up and down to open and close the intake passage 2 is slidably fitted into the throttle guide cylinder 3, and fuel is always stored at a specified level in the float chamber 4.

A main fuel nozzle 7 that communicates with the oil level of the float chamber 4 through a main fuel jet 6 opens at the bottom of the intake passage 2 directly below the throttle valve 5, and a needle valve 8 that moves up and down integrally with the throttle valve 5. is inserted into the nozzle 7.

The throttle valve 5 is opened (raised) by pulling a throttle wire 9 connected thereto, and closed (lowered) by the elastic force of a return spring 10 compressed within the throttle valve guide cylinder 3.

A bypass 11 having a sufficiently smaller diameter is connected to the intake passage 2 so that the throttle valve 5 bypasses it. A cylindrical valve chamber 12 is formed in the middle of this bypass 11 so as to cross it, and a float chamber 4 is connected to the bottom surface of this valve chamber 12 via a starting fuel jet 13.
The starting fuel nozzle 14, which communicates below the oil level, is opened. At that time, the opening end of the nozzle 14 is connected to the valve chamber 12.
An annular groove 15 is formed around the open end of the nozzle 14 so as to slightly protrude above the bottom surface of the nozzle.

The valve chamber 12 accommodates a piston-type starting valve 16 that can be raised and lowered to open and close the bypass 11 and the starting fuel nozzle 14 at the same time, and an operating rod 17 that protrudes outward from the upper part of the valve chamber 12 is provided at the upper end of the starting valve 16. are connected.

Therefore, when starting the engine cold, when the throttle valve 5 is closed, the starting valve 16 is pulled up to open the bypass 11 and the starting fuel nozzle 14, and the engine is cranked, the cranking negative pressure is bypassed. 11, the air in the upstream part of the intake passage 2 is sucked into the bypass 11, and at the same time, the air in the float chamber 4
The fuel inside is bypassed from the starting fuel nozzle 14 to the bypass 11.
The air and fuel are mixed to form a rich starting mixture, which exits the bypass 11 and is supplied to the engine to quickly start the engine. After starting or warming up the engine, push down the starting valve 16 to open the bypass 11 and starting fuel nozzle 14.
is closed, and the supply of the rich mixture is stopped.

By the way, as shown in FIG. 3, the starting valve 16 of the conventional starting device includes a piston-shaped metal first valve part 16a that is slidably fitted into the inner surface of the valve chamber 12, and this first valve part 16a. It consists of a plate-shaped second valve part 16b made of rubber that is fitted into a recess 18 on the lower surface, and the second valve part 16b is fixed by caulking the outer circumference of the lower end of the first valve part 16a. In the lowered position of the starting valve 16, the first valve part 16a closes the opening of the bypass 11 to the valve chamber 12 with its outer circumferential surface, and the second valve part 16b elastically contacts the upper end surface of the starting fuel nozzle 14. The opening is closed by pressing, and at that time,
Since the outer peripheral portion of the lower end of the first valve portion 16a is allowed to enter the annular groove 15, sufficient adhesion force can be provided between the second valve portion 16b and the starting fuel nozzle 14. Thus, the conventional starting valve 16 has two parts, one
6a and 16b, and since both have to be connected, it takes time and effort to manufacture, which is one of the reasons for hindering cost reduction of the starter device.

Furthermore, in the conventional starting device described above, when the first and second valve portions 16a, b of the starting valve 16 are slightly opened, the flow velocity of air passing through these valve portions 16a, 16b increases. Starting fuel nozzle 14
The amount of fuel sucked out from the valve portion becomes relatively large compared to the amount of air passing through the valve portion, and the starting air-fuel mixture tends to become excessively rich, which poses a problem in terms of exhaust gas countermeasures.

The present invention has been proposed in view of the above, and an object of the present invention is to provide a device with a simple structure that can eliminate all of the problems of conventional devices.

In order to achieve this purpose, the present invention
A cylindrical valve chamber 12 is formed across the bypass that bypasses the throttle valve and is connected to the intake passage, and a starting fuel nozzle is opened at one end surface of this valve chamber. A piston-type starter valve that can be opened and closed is accommodated in the valve chamber.
In the starting device for a carburetor, the starting valve includes a cylindrical first valve portion that can slidably fit into the inner circumferential surface of the valve chamber to close the bypass, and an opening edge of the starting fuel nozzle. and a hollow conical second valve part on which the outer peripheral surface can be seated, and both valve parts are integrally molded from synthetic resin, and the second valve part imparts elasticity to the first valve part. The first valve portion is preferably surrounded by an annular recess formed inside the first valve portion.

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

The starter valve 16 includes a cylindrical first valve part 16A that is slidably fitted into the inner circumferential surface of the valve chamber 12, and a hollow cone disposed with an annular gap 19 inside the first valve part 16A. It consists of a second valve part 16B with a spherical shape, and a connecting part 16C which is connected to the upper part of the first valve part 16A and has a spherical connecting hole 20 in the center, and these three parts 16A, 16
B and 16C are integrally molded from synthetic resin. An operating rod 17 is connected to the starting valve 16 by fitting its spherical enlarged end 21 into a connecting hole 20 .

Therefore, when the starting valve 16 is in the downward position, the first valve portion 16A is connected to the valve chamber 1 of the bypass 11 by its outer peripheral surface.
2, and the second valve portion 16B has its outer peripheral surface seated on the opening edge of the starting fuel nozzle 14 to close the nozzle 14. In this case, in particular, the first valve part 16A has appropriate elasticity due to the presence of the inner annular gap 19, so it fits well into the inner circumferential surface of the valve chamber 12 and reliably closes the bypass 11. The valve part 16B also has sufficient elasticity due to the existence of the above-mentioned void 19 and its own hollow part, so that it fits well into the opening edge of the starting fuel nozzle 14 due to the self-aligning effect due to the conical shape. can be closed securely. Also,
The first valve part 16A has its lower end entered into the annular groove 15, so that the starting fuel nozzle 1 of the second valve part 16B
4. Does not interfere with adhesion to the edge of the opening in any way.

By the way, the first and second valve parts 16A of the starting valve 16,
16B is slightly open, these valve parts 16
Since the flow of air passing near A and 16B at high speed can be greatly disturbed by the presence of the annular gap 19 between both valve portions 16A and 16B, the amount of fuel sucked out from the starting fuel nozzle 14 by the high speed air can be reduced. can be reduced, thereby suppressing the tendency for the mixture to become over-enriched.

As described above, according to the present invention, the cylinder-shaped valve chamber 12 is formed in the bypass 11 that bypasses the throttle valve 5 and is connected to the intake passage 2, and that crosses the bypass 11, and the cylinder-shaped valve chamber 12 is formed on one end surface of the valve chamber 12. The starting fuel nozzle 14 is opened, and a piston-type starting valve 16 capable of opening and closing the bypass 11 and the starting fuel nozzle 14 is inserted into the valve chamber 12.
A cylindrical first valve portion 16A that can slidably fit the starter valve 16 into the inner circumferential surface of the valve chamber 12 to close the bypass 11. and a hollow conical second part whose outer peripheral surface can be seated on the opening edge of the starting fuel nozzle 14.
The second valve part 16B is composed of a valve part 16B, and both the valve parts 16A and 16B are integrally molded from synthetic resin, and the second valve part 16B is formed by the first valve part 16A in order to impart elasticity to the first valve part 16A. Since the starting valve 16 is surrounded by an annular recess 19 formed inside the starting valve 16, the starting valve 16 can be molded as a single component from synthetic resin at once, thereby reducing its cost and, by extension, the cost of the starting device as a whole. Moreover, the first valve portion 16A
has appropriate elasticity due to the presence of the annular gap 19 inside thereof, so it fits well into the inner circumferential surface of the valve chamber 12 and can reliably close the bypass 11. On the other hand, the second valve portion 16B also , possesses appropriate elasticity due to the existence of its own hollow part and the annular gap 19, so it has a self-aligning effect due to its conical shape and fits well to the opening edge of the starting fuel nozzle 14, ensuring that the nozzle 14 is closed. can do. Also, the first and second valve portions 16A, B of the starting valve 16
When the valve portions 16A, 1 are slightly open, the valve portions 16A, 1
Since the flow of air attempting to pass near 6B at high speed can be greatly disturbed by the presence of the annular gap 19 between both valve portions 16A and 16B, the amount of fuel sucked out from the starting fuel nozzle 14 by the high speed air is reduced. Thus, the air-fuel mixture can always be adjusted to the appropriate air-fuel ratio. As described above, the annular gap 19 has both the original function of imparting elasticity to the first valve part 16A and the function of causing turbulence in the high-speed air passing through the valve parts 16A and 16B. , which can contribute to simplifying the structure of the valve.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional side view of a carburetor equipped with a starting device according to an embodiment of the present invention, Fig. 2 is an enlarged view of the main parts of the starting device, and Fig. 3 is an enlarged view of the main parts of a conventional starting device. It is. 2... Intake path, 5... Throttle valve, 11... Bypass, 12... Valve chamber, 14... Starting fuel nozzle, 1
6...Starting valve, 16A, 16B...First valve part, second valve part, 19...Gap.

Claims (1)

[Scope of utility model registration request] A cylindrical valve chamber 12 bypassing the throttle valve 5 and crossing it to a bypass 11 connected to the intake duct.
A starting fuel nozzle 14 is opened at one end face of the valve chamber 12, and a piston-type starting valve 16 capable of opening and closing the bypass 11 and the starting fuel nozzle 14 is accommodated in the valve chamber 12. In the starting device, the starting valve 16 includes a cylindrical first valve portion 16A that can slidably fit into the inner circumferential surface of the valve chamber 12 to close the bypass 11, and a starting fuel nozzle 14. It is composed of a hollow conical second valve part 16B whose outer peripheral surface can be seated on the opening edge, and
These two valve parts 16A, 16B are integrally molded from synthetic resin, and the second valve part 16B is different from the first valve part 1.
A starting device for a carburetor which is surrounded by an annular recess 19 formed inside the first valve portion 16A to impart elasticity to the first valve portion 6A.