JPS623312B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel tank that can prevent water in the fuel tank from being sucked into a suction pipe.

Generally, automobile fuels such as gasoline contain water, so water accumulates at the bottom of the fuel tank, and when this water is sucked into the suction pipe by the pump, it can cause damage to vehicles parked overnight in the winter. When the suction pipe freezes, the suction pipe becomes blocked, making it impossible to supply fuel to the engine, resulting in the problem that the engine will not start. Conventionally, in order to prevent water from the fuel tank from being sucked into the suction pipe, a shielding plate is provided between the suction pipe opening near the bottom plate of the fuel tank and the bottom plate. There was a device that prevented the water accumulated under the suction pipe from being sucked into the suction pipe (1986-
No. 45824).

However, although the conventional fuel tank described above is effective in preventing the water accumulated at the bottom of the fuel tank from being sucked in, there is a problem in that the water mixed in the fuel is sucked in together with the fuel.

This invention has been made in view of the above-mentioned problems of the conventional fuel tank, and is provided with a convex portion at the bottom of the fuel tank, and furthermore, a cylindrical sub-tank having at least an upper surface is provided above the convex portion. A suction pipe suction port is arranged in the center of the upper surface of the sub-tank so that the pump can suck in fuel, and a return pipe outlet is arranged on the upper surface of the sub-tank toward the circumferential direction of the inner circumferential wall of the sub-tank. By creating a swirling flow in the sub-tank using excess fuel returned from the pump, centrifugal force separates water mixed in the fuel from the fuel and draws the water into the suction pipe. The purpose of the present invention is to provide a fuel tank designed to prevent this.

An embodiment of the present invention will be described below with reference to the drawings.

1 to 4 show a first embodiment of the present invention. First, in FIG. 1 showing the fuel supply system of an engine, 1 is a fuel tank, and the fuel 11 in the fuel tank 1 is fed through a filter. 4 into the pump 2 through the suction pipe 3,
From this pump 2 through a fuel supply passage 5 to a carburetor 6
is supplied to the float chamber 6a, and is sucked out and vaporized by the intake negative pressure of the engine 7 in the carburetor 6,
The air is mixed with air from the air cleaner 8 and sucked into the engine 7. Among the fuel sucked into the pump 2, the remaining fuel when the liquid level in the float chamber 6a reaches a predetermined level is returned to the fuel tank 1 through the return pipe 9 as surplus fuel. It's becoming like that. The suction pipe 3 and return pipe 9 are attached to the fuel tank 1 by penetrating and fixing these pipes 3 and 9 to the ceiling plate 1a of the tank 1.

As shown in FIGS. 2 to 4, a circular convex portion 1c having a trapezoidal cross section is formed on the bottom plate 1b of the fuel tank 1, and the convex portion 1c
A cylindrical sub-tank 10 is arranged above, and the sub-tank 10 has an outer circumference 10a and an upper part 1.
0b, the size of which is slightly larger than the convex portion 1c of the fuel tank 1, and the outer peripheral portion 10a.
A gap 12 is provided between the lower end of the sub-tank 10 and the bottom plate 1b, which serves as a communication port for communicating the inside and outside of the sub-tank 10, and a plurality of communication ports 10c are also formed in the upper part 10b.

Further, the suction pipe 3 is fixed through the central part 10f of the upper part 10b of the sub-tank 10, and the suction pipe 3 has a suction port 3a.
is opened downward inside the sub-tank 10, and the return pipe 9 is fixed through the upper part 10b.
The tip 9a of the inner peripheral wall 10g of the sub tank 10
is curved in the circumferential direction, and its air outlet 9b is open in the circumferential direction.

In this way, the sub-tank 10 is suspended and fixed to the fuel tank 1 by the suction pipe 3 and the return pipe 9.

According to the fuel tank having such a configuration, when there is a certain amount of fuel 11 in the fuel tank 1, the bottom plate 1b of the fuel tank 1 and the outer peripheral part 1 of the sub-tank 10
Since the fuel 11 enters into the sub-tank 10 through the gap 12 between the sub-tank 10 and the sub-tank 10 or the communication port 10c of the upper part 10b of the sub-tank 10, there is always fuel 11 in the sub-tank 10. and pump 2
The surplus fuel returned from the outlet is blown out from the outlet 9b of the return pipe 9 in the circumferential direction of the inner circumferential wall 10g of the sub-tank 10, so that a swirling flow is generated in the sub-tank 10 as shown in FIG. Since water has a higher specific gravity than the fuel, it is separated from the fuel by the centrifugal force caused by the swirling flow, and this separated water is discharged to the outside of the sub-tank 10 through the gap 12 between the outer periphery 10a of the sub-tank 10 and the bottom plate 1b. . Therefore, the only fuel remaining in the sub-tank 10, especially near the center, is the fuel from which water has been completely separated and removed, and only such fuel is sucked into the suction pipe 3 provided in the center of the sub-tank 10 and pumped. 2 to the engine 7.

In the above embodiment, the sub-tank 10 was suspended and fixed to the ceiling plate 1a of the fuel tank 1 by the suction pipe 3 and the return pipe 9, but there are various other methods for supporting the sub-tank 10. For example, it may be fixed by welding to the bottom plate 1b of the fuel tank 1 via a plurality of supports.

FIG. 5 shows a second embodiment of the present invention, in which the same reference numerals as in FIGS. 1 to 4 indicate the same parts. In this embodiment, the cylindrical sub-tank 10 is provided with not only an upper part 10b but also a bottom plate 10d. A plurality of communication ports 10e are formed at the lower end of the outer peripheral portion 10a of the sub-tank 10 to communicate the inside and outside of the sub-tank 10.

In this embodiment, water mixed in the fuel is separated from the fuel by the swirling flow inside the sub-tank 10, and then discharged to the outside of the sub-tank 10 from the communication port 10e, and only the fuel containing no water is passed through the suction pipe. It gets sucked into 3.

As described above, according to the fuel tank according to the present invention, a convex portion is provided at the bottom of the fuel tank, and a cylindrical sub-tank having at least an upper surface is provided above the convex portion. The outlet of the return pipe is arranged in the circumferential direction of the inner circumferential wall of the sub-tank, and the excess fuel from the pump generates a swirling flow inside the sub-tank, thereby removing moisture mixed in the fuel. It has the effect of being able to reliably separate it from the fuel and supplying only fuel that does not contain water to the engine.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a fuel supply system for an engine including a fuel tank according to the present invention, FIG. 2 is a perspective view of a main part of a first embodiment of the present invention, and FIG. 3 is a main part of the above embodiment. FIG. 4 is a cross-sectional plan view of the main part of the above embodiment, and FIG. 5 is a cross-sectional side view of the main part of the second embodiment of the present invention. 1... Fuel tank, 2... Pump, 3... Suction pipe, 3a... Suction port, 7... Engine, 9... Return pipe, 9b... Outlet, 10... Sub tank,
10a...Outer peripheral part, 10b...Upper part, 10c...Communication port, 10g...Inner peripheral wall, 11...Fuel, 12...Communication port.

Claims (1)

[Claims] 1. A convex portion protruding upward is provided at the bottom of the fuel tank, and a cylindrical sub-tank having at least an upper surface is installed above the convex portion, and a cylindrical sub-tank having at least an upper surface is provided on the lower outer periphery and the upper surface of the sub-tank, respectively. A communication port is formed, and a suction port for a suction pipe for supplying fuel to the engine with a pump is arranged in the center of the upper surface of the sub-tank, and a pump is arranged in the upper surface of the sub-tank in the circumferential direction of the inner circumferential wall of the sub-tank. A fuel tank characterized in that a return pipe is provided with an outlet for returning surplus fuel from the return pipe, and the surplus fuel from the return pipe provides a swirling flow inside the sub-tank.