JPS62267550A - Fuel feed device for vehicle - Google Patents

Abstract

PURPOSE:To enable reutilization of fuel overflowing a float chamber without dumping the overflow fuel, by a method wherein a fuel return pipe, being open in a position above a liquid level in the float chamber, is communicated to a fuel tank through a fuel pump. CONSTITUTION:Fuel in a fuel tank 17 flows in a float chamber 12 as it is regulated by a float valve 19 with the aid of a usual fuel pump. An overflow pipe 20, being open in a position above a liquid level L1 in the float chamber, is installed in the float chamber 12. The overflow pipe 20 is communicated to the fuel tank 17 through a pump 22. A pump 25 is communicated to a chamber 27 below the under surface of a diaphragm 26 through a suction pipe by means of a joint 3, and the diaphragm 26 is actuated by means of pulsation of intake air. When a liquid level in the float chamber is raised resulting from inclination of a car body, fuel flowing over the opening of an overflow pipe 13 is sucked with the aid of a pump 22 and is returned back to the fuel tank 17 again.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel supply device equipped with a float type carburetor.

[Prior art]

For example, in a carburetor used in a motorcycle, when the curved surface inside the float chamber exceeds a certain height, excess fuel flows out through an overflow pipe to maintain the oil level in the float chamber at a constant level. ing.

[Problem that the invention seeks to solve]

However, in the past, the fuel flowing out from the overflow vibrator was directly discharged to the outside, resulting in wasted fuel and a problem that adversely affected fuel efficiency.

[Means for solving problems]

Therefore, in the present invention, the outlet of the overflow passage that opens into the float chamber of the carburetor is communicated with a position higher than the highest liquid level of the fuel tank, and the communication passage connecting the overflow passage and the fuel tank is connected to the above-mentioned The fuel tank is characterized by being equipped with a pump that pumps the fuel flowing out from the overflow passage toward the fuel tank.

[Effect]

According to this arrangement, even if excess fuel in the float chamber is discharged to the outside through the overflow passage,
Since the outlet of this overflow passage is connected to the fuel tank via a pump, the fuel that has been thrown away outside is returned to the fuel tank.

Therefore, fuel is not wasted and fuel efficiency can be improved.

[Embodiments of the invention]

The present invention will be explained below based on an embodiment shown in the drawings.

Reference numeral 1 in FIG. 1 indicates a two-stroke engine for a motorcycle, and a VM type carburetor 4 is connected to an intake port 2 of the engine 1 via a joint 3. A venturi passage connected to the intake port 2 is formed in the body 5 of the carburetor 4, and a piston-shaped throttle valve 7 is provided in the venturi passage 6. A needle valve 8 hanging down from the throttle valve 7 is inserted into a needle jet 9 that opens into the venturi passage 6, and this needle jet 9 is communicated with a float chamber 12 in a float case 11 via a main jet 10. There is. The float chamber 12 accommodates a float 13 that follows the fuel liquid level in the float chamber 12.
The float arm 14 is pivotally supported on the body 5 side.

Further, a fuel passage 15 that opens into the float chamber [2 is formed inside the body 5, and this fuel passage 15 is connected to a fuel tank 17 installed above the carburetor 4 via a fuel vibrator IB. . Float chamber 1 of fuel passage 15
A float valve 19 is supported at the open end of the fuel passage 15 via a valve seat 18, and this float valve 19 opens and closes the open end of the fuel passage 15 in conjunction with the float arm 14. .

An overflow vibe 20 extending in the vertical direction is supported in the float chamber 12, and the upper end of this overflow vibe 20 is opened above the appropriate oil 1ωL1 in the float chamber 12, and the lower end is opened above the bottom surface of the float case 11. It communicates with the outlet 21 of. This discharge port 21 is communicated with a position higher than the highest liquid level L2 of the fuel tank 17 via a fuel return vibe 23 serving as a communication path, and an overflow vibe 20 is provided at the upstream end of this fuel return vibe 23. Fuel flowing out from fuel tank 1
A pump 22 is provided for pumping water to 7.

By the way, the pump 22 of this embodiment is a pulse pump that uses the pulsating pressure of intake air as a driving source, and is integrated into the bottom of the float case 11.

The details of this pump 22 will be explained with reference to FIGS. 3 to 5. A pump housing 25 is fastened to the outer bottom surface of the float case 11 via screws 38, and the pump housing 25 and the float Case 11
A pressure introduction chamber 27 and a pump chamber 28 partitioned by a diaphragm 26 are formed on the abutting surface. The pressure introduction chamber 27 is connected to the pulse pressure outlet 3a of the joint 3 via a pressure port 29 and a hose 30,
The diaphragm 2B is vertically displaced by the pulsating pressure of the intake air acting on the pressure introduction chamber 27.

Further, the pump chamber 28 is communicated with an inflow passage 31 and an outflow passage 32 provided on the abutment surface of the float case 11, and this inflow passage 31 is communicated via a communication path 33 provided on the abutment surface of the pump housing 25. It communicates with the discharge port 21 mentioned above. A large mouth valve 34 using a diaphragm is provided in the inflow passage 31 connected to the communication passage 33, and as shown in FIG. When the diaphragm 26 is displaced downward, it is elastically deformed toward the inflow passage 31 and opens the entrance of the inflow passage 31.

On the other hand, the outflow passage 32 is communicated with a discharge port 35 provided in the pump housing 25, and an outlet valve 3B using a diaphragm is provided at the outlet of the outflow passage 32 that is connected to the discharge port 35. This outlet valve 3B is the fifth
As shown in the figure, when positive pressure acts in the pressure introduction chamber 27 and the diaphragm 26 is displaced upward, the discharge port 35
It is elastically deformed toward the side and opens the outlet of the outflow passage 32.

Therefore, such a pump 22 sucks the fuel that has flowed into the overflow vibe 20 into the pump chamber 28 by displacement of the diaphragm 2B based on the pressure change in the pressure introduction chamber 27, and pumps the fuel from there to the discharge port 35. The fuel return pipe 23 is connected to the discharge port 35.

Note that a pump 22 is installed in the middle of this fuel return vibe 23.
Check valve 3 that only allows flow from the fuel tank 17 toward the fuel tank 17
7 is provided.

In such a configuration, if the liquid level in the float chamber 12 tilts due to, for example, driving on a rough road, the float valve 19 opens and fuel flows into the float chamber 12 even though the oil level has reached an appropriate level. This may cause the oil level in the float chamber 12 to exceed an appropriate level. Then, this excess fuel is discharged to the outside of the float chamber 12 through the overflow pipe 20, but the fuel flowing out from the overflow vibe 20 is sucked into the pump chamber 28 of the pump 22 and from there to the discharge port 35. The fuel is then pressure-fed to the fuel return vibe 23 and returned to the fuel tank 17.

Therefore, it becomes possible to reuse the fuel that has conventionally been discarded outside, so the fuel is not wasted and fuel efficiency is improved.

In addition, in this embodiment, a pulse pump 22 that uses the pulsating pressure of intake air as a driving source is used, and this pump 22 is integrated into the bottom of the float case 11, so that the piping from the overflow pipe 20 to the pump 22 is connected to the pump 22. can be omitted. At the same time, float case 1
1 is close to the joint 3 through which the intake air flows, the overall length of the hose 30 that guides the pulsating pressure can be shortened, and the piping around the carburetor, including the fuel return path, can be made compact.

In addition, in the above-mentioned embodiment, a pulse pump that utilizes the pulsating pressure of intake air is used, but the present invention is not limited to this, and for example, a plunger-type pump that is driven by power transmission from a crankshaft may be used. However, this pump may also be formed separately from the float case of the carburetor and installed in the middle of the fuel return pipe.

Furthermore, when the pump is assembled into a float case, a passage connecting the pressure introduction chamber and the venturi passage may be formed in the body of the vaporizer or the float case.

〔Effect of the invention〕

According to the present invention described in detail above, the fuel flowing out from the overflow passage can be returned to the fuel tank, so that fuel is not wasted, and fuel efficiency can be improved.

[BRIEF DESCRIPTION OF THE DRAWINGS] The drawings show one embodiment of the present invention, and FIG. 1 is a side view of the entire device, FIG. 2 is a cross-sectional view of the vaporizer, and FIG.
4 and 5 are cross-sectional views taken along line 1, respectively, showing the operating state of the pump. 4... Vaporizer, 12... Float chamber, 13... Float, 19... Float valve, 20... Overflow passage (overflow vibe), 22... Pump,
23...Communication path (fuel return pipe). Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 4

Claims (1)

[Claims] A carburetor is provided that opens and closes a float valve using a float that follows the fuel level in the float chamber, and the outlet of the overflow passage that opens into the float chamber is located at a position higher than the highest level of the fuel tank. 1. A fuel supply device for a vehicle, characterized in that a pump is provided in a communication passage connecting the overflow passage and a fuel tank, and for pumping fuel flowing out from the overflow passage toward the fuel tank.