JPH0310030B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a carburetor, and particularly to a carburetor with an improved slow system.

[Prior Art] A carburetor has an idle port opened to the lower intake flow rate from the throttle valve fully closed position of the intake passage, and a bypass port opened to the intake air flow upstream side near the throttle valve fully closed position of the intake passage. The engine has a slow system that increases the amount of fuel supplied during low-speed operation such as no-load idling or low-load operation to supply a rich air-fuel mixture to stabilize low-speed rotation.

In the above carburetor, it is necessary to set the amount of fuel supplied to the slow system to an extent necessary to obtain smooth low-speed acceleration or slow-speed deceleration. However, the idle port that constitutes the slow system,
Since the bypass port is directly connected to the float chamber that stores fuel, fuel is supplied to the slow system even during steady operation at partial load or above, which does not require an increase in fuel, and no more fuel than necessary is consumed. There is the inconvenience of being exposed.

An object of the present invention is to rationally increase the amount of fuel in a carburetor during sudden deceleration or acceleration to ensure smooth deceleration or acceleration.

[Means for Solving the Problems] The present invention provides a vaporizer equipped with a float chamber for storing fuel, which includes an upper space that communicates with the atmosphere, and a fuel reservoir chamber that communicates with the float chamber and can store fuel. a throttle passage provided between the float chamber and the fuel reservoir chamber to regulate the flow rate of fuel; a suction passage having a suction port at the bottom of the fuel reservoir chamber; a throttle valve connected to the suction passage; It is equipped with a fuel pipe that opens at a position facing the outer periphery of the throttle valve when the throttle valve is rotated by a small angle from the fully closed position, and is further located above the suction port of the suction passage and below the horizontal plane passing through the oil level in the sub-float chamber. The fuel tank is equipped with a small hole that communicates between the fuel reservoir chamber and the fuel pipe.

[Function] According to the present invention, there are the following effects.

When the throttle valve is rotated at a small angle from fully closed, or more slowly until fully opened, a certain amount of fuel in the fuel reservoir can be supplied to the intake passage. This ensures smooth acceleration from low to medium speeds.

In the above, after the fuel accumulated in the fuel reservoir chamber is supplied, only the amount of fuel regulated by the throttle passage is supplied to the intake passage, so that fuel can be saved. That is, in the above case, the amount of fuel can be increased rationally.

When increasing a certain amount of fuel during sudden deceleration or acceleration, at the beginning of the increase, the oil level in the fuel reservoir is at a horizontal level that passes through the sub-float chamber oil level and is high, so both the small hole and the suction port By sucking fuel from the engine, more fuel can be supplied and the connection between deceleration and acceleration can be improved. In addition, in the later stages of fuel increase when the oil level in the fuel reservoir decreases, air is sucked through the small holes, thereby making it possible to stop supplying more fuel than necessary.

[Embodiment] FIG. 1 is a partially cutaway front view showing an embodiment of the present invention applied to an outboard engine, and FIG. 2 is a model diagram showing a slow system of the carburetor.

The carburetor 11 is composed of a central main body 11A and side sub-bodies 11B, and uses a variety of fuels, using kerosene as the main fuel and gasoline as an auxiliary fuel for acceleration. Therefore, a main float chamber 12A is provided in the lower part of the main body 11A to accommodate kerosene as the main fuel. Further, a sub-float chamber 12B is provided in the lower part of the sub-body 11B to accommodate gasoline as a sub-fuel.

Further, the carburetor 11 is of a two-bore type that can supply air-fuel mixture to each cylinder of the outboard engine through a separate intake cylinder (bore), and an intake passage 13 is formed in each intake cylinder. are doing. Each intake passage 13 can be opened and closed by each throttle valve 15 fixed to a single throttle valve shaft 14, respectively. That is, a throttle operating mechanism is connected to the throttle valve shaft 14 via a throttle lever 16, and the throttle valve 15 is operated by the operation of the throttle operating mechanism.
can be opened and closed within a range between a fully closed position and a fully open position. Further, a bench lily portion 17 is formed in each intake passage 13 on the upstream side of the throttle valve 15 . The main float chamber 1 is located in the bench lily section 17.
The tip opening of the main nozzle 18 that communicates with the main nozzle 2A is open and constitutes a main system. That is, during steady operation at a partial load or higher where the opening of the throttle valve 15 exceeds a certain angle, the amount of air flowing through the intake passage 13 increases, so kerosene is supplied from the main nozzle 18, causing the engine to rotate at medium speed. It is possible to rotate at high speed.

Further, the carburetor 11 has a slow system as schematically shown in FIG. That is, the intake passage 1
An idle port 19 is opened on the intake downstream side of the fully closed position of the throttle valve 15 at No. 3. Furthermore, bypass ports 20 and 21 are opened on the upstream side of the intake passage 13 near the fully closed position of the throttle valve 15. Above idle port 19, bypass port 20, 21
is connected to the sub-float chamber 12 via the slow passage 22.
It communicates with B. In addition, in FIG. 2, 23 indicates a slow air bleed.

Furthermore, the carburetor 11 has the idle port 1
9. In addition to the normal slow system consisting of bypass ports 20 and 21, the following slow system is provided. That is, the sub float chamber 1 of the sub body 11B
A fuel reservoir chamber 24 is formed in a portion adjacent to 2B. The fuel reservoir chamber 24 communicates with the sub-float chamber 12B via a fuel passage 25 and a throttle passage 26,
Gasoline in the sub-float chamber 12B can be stored. Further, a suction nozzle 27 serving as a suction passage is suspended in the fuel reservoir chamber 24 to a lower position facing the bottom thereof, and the suction nozzle 27 is connected to the main body 11.
When the throttle valve 15 in the intake passage 13 is rotated by a small angle from the fully closed position, the outer periphery of the throttle valve 15 is opened to the opposite position through the fuel passage 28 bored in the A and sub-body 11B. It is connected to the secondary bypass port 29. Note that a jet 30 is provided at the lowest end of the suction nozzle 27 located in the fuel reservoir chamber 24. In addition, a through hole 31 is provided at the lower end side of the suction nozzle 27 to function as a fuel suction or air bleed, and an air hole 31 is provided at the upper end side of the suction nozzle 27 located in the upper space of the fuel reservoir chamber 24. A through hole 32 is provided which functions as a bleed. Further, the upper space of the fuel reservoir chamber 24 is communicated with the atmosphere through a through hole 33 serving as an air vent.

The through hole 31, which communicates the fuel reservoir chamber 24 with the fuel passage 28, is located above the jet 30 of the suction nozzle 27 and below the horizontal plane passing through the oil surface of the sub-float chamber 12B. Therefore, at the beginning of fuel increase starting from the fully closed state of the throttle valve 15, the through hole 31 opens the sub-float chamber 1.
It is located below the oil level in the fuel reservoir chamber 24, which is at the same level as the oil level 2B. because,
When the throttle valve 15 is fully closed, there is no intake negative pressure in the fuel passage 28, and the fuel reservoir chamber 24 is connected to the sub-float chamber 12B, the throttle passage 26, and the fuel passage 25.
Because of this communication, the oil level in the fuel reservoir chamber 24 is at the same high level as the oil level in the sub-float chamber 12B.

Next, the operation of the slow system in the carburetor according to the above embodiment will be explained.

When the throttle valve 15 is close to fully closed, the idle port 19 is located under a negative pressure region, so gasoline in the sub-float chamber 12B flows from the idle port 19 through the slow passage 22. The air is supplied to the intake passage 13. Thereafter, when the throttle valve 15 is opened by operating the throttle operating mechanism, the bypass port 20,
21 is located under a negative pressure region, and gasoline in the sub-float chamber 12B is also supplied from the bypass ports 20 and 21 to the intake passage 13 via the slow passage 22.

However, in the embodiment described above, when the throttle valve 15 is in the fully closed position, the gasoline in the sub-float chamber 12B is stored in the fuel reservoir chamber 24 via the fuel passage 25 and the throttle passage 26. Ru. Therefore, in the low-speed acceleration range where the throttle valve 15 rotates from the fully closed position and exceeds the position facing the auxiliary bypass port 29, the gasoline in the fuel reservoir chamber 24 flows into the suction nozzle 27 from the jet 30 and the through hole 31. The fuel is sucked in, mixed with air from the through hole 32, and then supplied from the sub-bypass port 29 to the intake passage 13, thereby increasing the amount of fuel supplied to the slow system. As the gasoline in the fuel reservoir chamber 24 is supplied to the intake passage 13 as described above, when the storage level in the fuel reservoir chamber 24 drops below the through hole 31, the residual gasoline in the fuel reservoir chamber 24 , is sucked into the suction nozzle 27 from the jet 30, mixed with air from the through holes 31 and 32, that is, in a state where the mixture concentration gradually becomes thinner, and then supplied from the sub-bypass port 29 to the intake passage 13. be done. The solid line in FIG. 4 shows the supplied fuel Q with respect to the engine rotational speed N in the case where the sub-bypass port 29 is not provided, and the broken line shows the amount of fuel increased by the sub-bypass port 29.

Therefore, according to the above embodiment, the sub-bypass port 29 supplies only the amount of gasoline stored in the fuel reservoir chamber 24 to the intake passage 13, and the increase in amount from the sub-bypass port 29 occurs in the low-speed acceleration region. This is done only in the normal operating range, and no more than necessary increases are made in the steady operating range. That is, in the low speed acceleration range, the throttle valve 15
Even if the opening is held at an arbitrary intermediate opening or the opening is changed rapidly, the amount of fuel added to the intake passage 13 is always only the amount required to warm up the engine, that is, a substantially constant amount. , it becomes possible to suppress the set supply amount in the slow system consisting of the normal idle port 19 and the bypass ports 20 and 21 to the required amount, and reduce the amount of fuel consumed.

In the case of the above embodiment, when the throttle valve 15 is in the fully open position, the oil flows into the fuel reservoir chamber 24 through the throttle passage 26 due to the difference in oil level between the sub-float chamber 12B and the fuel reservoir chamber 24. Due to the existence of a pressure difference between the atmospheric pressure that acts on the upper space of the fuel reservoir chamber 24 through the through hole 33 and the negative intake pressure that acts on the sub-bypass port 29, a small amount of gasoline constantly flows out from the sub-bypass port 29. The fuel will not leak out and be stored in the fuel reservoir chamber 24. Therefore, in the above embodiment, the throttle valve 1
5 is closed from the fully open side to the fully closed side, no increase in the amount from the auxiliary bypass port 29 can be expected. However, in this low-speed deceleration range, sufficient gasoline can be supplied from the normal slow system consisting of the idle port 19 and the bypass ports 20 and 21 to achieve smooth low-speed deceleration operation, resulting in unstable operation. It never invites.

In addition, the bypass port 2 in the above embodiment
0 and 21 may be removed, and the slow system may be configured by only the idle port 19 and the sub-bypass port 29.

According to the above embodiment, there are the following effects.

When the throttle valve 15 is rotated by a small angle from fully closed, or when it is slowly rotated to fully open, a certain amount of gasoline in the fuel reservoir chamber 24 can be supplied to the intake passage 13. This ensures smooth acceleration from low to medium speeds.

In the above, after the supplementary fuel accumulated in the fuel reservoir chamber 24 is supplied, only the amount of gasoline regulated by the throttle passage 26 is supplied to the intake passage 13, so that gasoline can be saved. That is, in the above case, the amount of gasoline can be increased rationally.

When increasing a certain amount of fuel during sudden deceleration or acceleration, at the beginning of the increase, the oil level in the fuel reservoir chamber 24 is high as it is at the level of the horizontal plane passing through the oil level in the sub-float chamber 12B. By sucking fuel from both jets 30, more fuel can be supplied, reducing deceleration and
Alternatively, the connection of acceleration can be improved. Furthermore, in the later stages of fuel increase when the oil level in the fuel reservoir chamber 24 decreases, air is sucked through the through holes 31, thereby making it possible to stop supplying more fuel than necessary.

[Effects of the Invention] As described above, according to the present invention, it is possible to rationally increase the amount of fuel in the carburetor during sudden deceleration or acceleration, and to ensure smooth deceleration or acceleration.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway front view of an embodiment of the present invention, Fig. 2 is a model diagram showing the slow system of the carburetor, and Fig. 3 is a diagram showing the fuel supply state of the carburetor. It is. 11... Carburizer, 12B... Sub-float chamber, 1
3...Intake passage, 15...Throttle valve, 1
7... Bench lily part, 24... Fuel reservoir chamber, 26
...Aperture passage, 27...Suction nozzle, 29...Sub-bypass port, 12A...Main float chamber, 30...
...Jet, 31...Through hole.

Claims (1)

[Claims] 1. In a carburetor equipped with a float chamber for storing fuel, a fuel reservoir chamber is provided with an upper space communicating with the atmosphere and communicates with the float chamber and can store fuel, and a space between the float chamber and the fuel reservoir chamber. a throttle passage provided to regulate the flow rate of fuel; a suction passage having a suction port at the bottom of the fuel reservoir;
A fuel pipe is connected to the suction passage and opens at a position facing the outer periphery of the throttle valve when the throttle valve is rotated by a small angle from a fully closed position in the intake passage, and further above the suction port of the suction passage; A carburetor equipped with a small hole that communicates between the fuel reservoir chamber and the fuel pipe at a position below the horizontal plane passing through the float chamber oil level.