JPS6319701B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention controls the amount of fuel supplied to the intake passage only within a predetermined opening range of the throttle valve.
The present invention relates to a device that reduces engine fuel consumption.

[Conventional technology]

By the way, as an example of prior art related to the above-mentioned device for reducing fuel consumption, there is one disclosed in Japanese Patent Publication No. 17506/1983, which discloses that an opening provided in an intake passage is connected to a negative pressure passage. The negative pressure passage is connected to the upper part of the fuel surface of the float chamber through the valve, and the negative pressure passage is provided with an on-off valve of the throttle valve, which is fully closed when the throttle valve is fully opened and fully opened during low-output economical operation. The air vent, which opens above the surface and communicates with the atmosphere, is equipped with a diaphragm.

[Problems to be solved by the invention]

However, in the above-mentioned prior art example, since the air vent opening on the upper surface of the fuel in the float chamber is provided with a throttle, the throttle valve in which negative pressure acts on the upper surface of the fuel in the float chamber through the negative pressure passage. When the opening of the throttle valve is increased from the predetermined opening range to a high-load operating range due to sudden acceleration, the upper surface of the fuel in the float chamber does not reach atmospheric pressure without delay, so the fuel is not supplied to the intake passage. There are problems such as the engine running out of fuel due to lack of fuel. An object of the present invention is to provide a fuel consumption reducing device for a carburetor that eliminates such problems.

[Means to solve the problem]

The present invention has the following technical means to achieve the above object. That is, a negative pressure passage opened in the crankcase is communicated above the fuel surface of the float chamber, and an air vent opened above the fuel surface of the float chamber is opened to the atmosphere, and the negative pressure passage is connected to the crankcase. a negative pressure adjusting means for attenuating pressure pulsations within the throttle valve; a negative pressure adjusting means disposed in the negative pressure passage closer to the float chamber than the negative pressure adjusting means, and opening the negative pressure passage only within a predetermined opening range of the throttle valve; and opening/closing means for narrowing the air vent only within the predetermined opening degree range,
The present invention is characterized in that the amount of fuel supplied to the intake passage is controlled when the throttle valve is in a predetermined opening range.

【Example】

Hereinafter, one embodiment of the present invention will be specifically described with reference to the drawings. In FIG. 1, numeral 1 is the carburetor main body;
An intake passage 2 is formed in this carburetor body 1, and within a float chamber wall 3 fixed to the carburetor body 1,
A float chamber 4 is formed. This float chamber 4 has a built-in float (not shown), and is configured to be supplied with fuel 5 so as to maintain a predetermined fuel level 6. A main nozzle 7 is opened in the bench lily portion 2a of the intake passage 2, and this nozzle 7 is communicated with the lower part of the float chamber 4 via a main jet 8. A throttle valve 9 is provided in the intake passage 2, and a throttle shaft 10 fixed to the throttle valve 9 is rotatably supported by the carburetor body 1. Further, in FIG. 1, reference numeral 11 is a crank case of an air-cooled general-purpose engine, and this case 1
One end of a negative pressure passage 13 is opened above the lubricating oil level 12 in the float chamber 1, and the other end is opened above the fuel surface 6 above the float chamber 4. 14 are provided. This opening/closing means 14 opens the negative pressure passage 13 only in the normal opening range of the throttle valve 9, and as shown in FIGS.
An arcuate groove 15 extending in the circumferential direction is formed on the outer peripheral surface of one end fitted to the carburetor main body 1, and the crankcase side portion 13a and the float chamber side portion of the negative pressure passage 13 are connected through the arcuate groove 15. 13b are configured to communicate with each other only in the normal opening range α of the throttle valve 9. Furthermore, one end of an air vent 16 is opened in the upper part of the float chamber 4, and this air vent 16 is opened to the atmosphere via a throttle mechanism 17, which will be described later. This throttle mechanism 17 has an arcuate concave groove 18 formed along the circumferential direction in a portion of the outer peripheral surface of the throttle shaft 10 opposite to the arcuate groove 15.
A protrusion 19 is provided in the center of this groove 18, and the aperture 2
0 is formed, and in the normal opening range α of the throttle valve 9, the float chamber side part 16a and the atmospheric pressure side part 16b of the air vent 16 communicate through the throttle 20. It is now possible to communicate without going through. A negative pressure adjusting means 21 consisting of a surge tank is provided between the opening end of the negative pressure passage 13 on the crankcase 11 side and the opening/closing means 14. In the carburetor fuel efficiency reduction device configured as described above, in the normal opening range α of the throttle valve 9, as shown in FIG. are communicated through the arcuate groove 15, so that during one cycle of engine operation, as shown in FIG. 5, the positive pressure period is shorter than the negative pressure period and the positive pressure value is smaller, so The pressure inside the crankcase 11 becomes negative. The negative pressure inside the crankcase 11 is pulsated by the negative pressure adjusting means 21 and acts on the upper part of the fuel surface 6 of the float chamber 4, and this part becomes negative pressure, so that the negative pressure in the intake passage 2 and The difference between the negative pressure in the upper part of the fuel surface 6 of the float chamber 4 is reduced. For this reason, the amount of fuel discharged from the main nozzle 7 to the bench lily portion 2a of the intake passage 2 is always at atmospheric pressure above the fuel surface 6 of the conventional float chamber due to the air vent regardless of the opening degree of the throttle valve. The air-fuel mixture becomes lean,
Therefore, fuel consumption is reduced. At this time, the float chamber side portion 16a and the atmosphere side portion 16b of the air vent 16 are connected to the aperture 2.
Air vent 1
Air introduced into the float chamber 4 from the throttle 20
By being squeezed by the above-mentioned bench lily part 2
The effect of reducing the amount of fuel discharged to a is promoted. Further, when the throttle valve 9 is opened at a lower opening than the normal opening range α, as shown in FIG. 3, the negative pressure passage 1
Since the crankcase side portion 13a and the float chamber side portion 13b of No. 3 are deviated from the arcuate groove 15, the negative pressure inside the crankcase 11 does not act on the float chamber 4, and the air vent 16 is not connected to the float chamber side portion 16a. and the atmosphere side portion 16b are the aperture 20
Since the other side is communicated through the groove 18, the atmosphere is introduced into the fuel surface 6 of the float chamber 4 without being restricted by the throttle 20, and therefore the upper part of the fuel surface 6 in the float chamber 4 becomes atmospheric pressure. Furthermore, even when the throttle valve 9 is fully open, which is higher than the normal opening range α, both parts 13 of the negative pressure passage 13
a, 13b are removed from the arcuate groove 15, no negative pressure is applied to the float chamber 4, and both parts 16a, 16b of the air vent 16 are closed to the throttle 20.
Since the other side is communicated through the groove 18, the atmosphere is introduced into the float chamber 4 without being restricted by the throttle 20, and the portion above the fuel surface 6 in the float chamber 4 becomes atmospheric pressure. Therefore, the operating state is changed from the load operation range within the predetermined opening range of the throttle valve where the negative pressure in the crankcase 11 is acting above the fuel surface 6 of the float chamber 4 to the high load operation range with sudden acceleration. When the pressure changes, the pressure above the fuel surface 6 of the float chamber 4 reaches atmospheric pressure without any delay, so that sufficient fuel can be supplied to the bench lily section 2a to cope with the high load, and therefore the engine can breathe smoothly. There is no such thing as making a mistake. From what has been described above, the air-fuel mixture is not diluted when the throttle valve 9 is not in the normal opening range α. That is, in this example, line a in FIG.
As shown in the figure, the float chamber is at negative pressure only in the throttle valve's normal opening range α, and is at atmospheric pressure at other times. Compared to line c, as shown by line b, the fuel consumption of this embodiment is reduced only in the normal opening range α of the throttle valve. Since the air-fuel mixture does not become diluted outside the throttle valve's normal opening range α, there is a risk of deterioration in no-load operation at low openings, a decrease in output during high-opening and high-load operation, and problems with air-cooled engines. There is no problem of high temperatures in engine parts or lubricating oil. Furthermore, since the negative pressure passage 13 is opened in the crankcase 11, a negative pressure smaller than the suction negative pressure can be applied to the float chamber 4, and the negative pressure adjusting means 21 is connected to this and the negative pressure passage 13. Coupled with the fact that pulsation of the negative pressure can be reduced by providing this, the negative pressure in the float chamber 4 can be easily controlled and stable operation can be performed. In the present invention, a throttle may be used as a negative pressure adjusting means provided in the suction passage to reduce the negative pressure in the crankcase, or a throttle and a surge tank may be provided in series.

【Effect of the invention】

As explained above, according to the present invention, the negative pressure passage is opened by the opening/closing means that opens only within a predetermined opening range of the throttle valve, and by guiding negative pressure from within the crankcase to above the fuel surface of the float chamber, the float It is possible to make the chamber negative pressure to dilute the mixture and reduce fuel consumption.On the other hand, when the throttle valve is operated at a low opening outside the above-mentioned predetermined opening range, at no-load operation, or at a high opening and at high load, Since the air-fuel mixture is not diluted, these problems that occur during operation can be eliminated, and furthermore,
When the operating condition changes from the load operation range within the specified opening range of the throttle valve where negative pressure in the crankcase is acting above the fuel surface of the float chamber to the high load operation area due to sudden acceleration, the float chamber Since the upper part of the fuel surface becomes atmospheric pressure without delay unlike the prior art example, a sufficient amount of fuel corresponding to the high load can be supplied to the bench lily part.
Therefore, the engine never takes a breather.
In addition, since the negative pressure in the crankcase is guided to the float chamber via the negative pressure adjustment means, there is less pulsation, and therefore a relatively small negative pressure can be guided to the float chamber, resulting in stable above-mentioned conditions. This has the effect of allowing you to expect it to work.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing an embodiment of the present invention, FIG. 2 is an enlarged cross-sectional view of the throttle valve at the normal opening along line A-A in FIG. 1, and FIG. FIG. 4 is an enlarged cross-sectional view at a low opening; FIG. 4 is a diagram showing the relationship between the throttle valve opening of the present invention and the pressure in the float chamber; and FIG.
The figure is a diagram showing fluctuations in pressure generated within the crankcase. 1... Carburetor body, 2... Intake passage, 2a...
Bench lily part, 3... Float chamber wall, 4... Float chamber, 5... Fuel, 6... Fuel surface, 7... Main nozzle, 8... Main jet, 9... Throttle valve, 10... Throttle shaft, 11...Crankcase, 12...Lubricating oil surface, 13...Negative pressure passage, 13a...Crankcase side portion, 13b...
...Float chamber side portion, 14...Opening/closing means, 15...
...Arc-shaped groove, 16...Air vent, 16a...Float chamber side part, 16b...Atmospheric side part, 17...
Aperture mechanism, 18...concave groove, 19...protrusion, 20...
...Aperture.

Claims (1)

[Claims] 1. A negative pressure passage opened in the crankcase is communicated with the air above the fuel surface of the float chamber, and an air vent opened above the fuel surface of the float chamber is opened to the atmosphere. a negative pressure adjusting means for attenuating pressure pulsations of the throttle valve; Fuel consumption reduction of a carburetor characterized in that an opening/closing means is provided to throttle the air vent only within the predetermined opening range, and the amount of fuel supplied to the intake passage is controlled when the throttle valve is in the predetermined opening range. Device.