JPS6123652Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to an improvement of a fuel supply device that guides the fuel in the fuel tank to the fuel pump, supplies it to the engine by the fuel pump, and returns excess fuel to the fuel tank. .

Generally, in this type of fuel supply device, the suction port of the feed pipe that feeds fuel to the fuel pump is provided at the bottom of the fuel tank, usually at the bottom, so that the fuel in the fuel tank can be supplied to the end. It is arranged as close as possible to the bottom surface of the recess (see, for example, Japanese Utility Model Application Publication No. 173439/1983).

For this reason, moisture, which has a higher specific gravity than the fuel, tends to accumulate near the suction port of the feed pipe, and in cold regions or during the winter, this moisture can freeze, clogging the feed pipe and causing accidents such as not being able to supply fuel. It was hot.

The present invention was developed to solve this problem, and when the feed pipe is frozen and cannot supply fuel, the return pipe that returns surplus fuel from the fuel pump to the fuel tank is used to supply fuel. The object of the present invention is to provide a fuel supply device that can perform the following steps.

Therefore, in the present invention, a first check valve that is located in the middle of the bypass passage that connects the feed pipe and the return pipe and allows fuel to pass from the return pipe side to the feed pipe side, and a branch of the bypass passage of the return pipe. A second check valve is installed on the discharge side of the pump from the pump side communication port of the section to block the passage of fuel to the discharge side of the pump.When the feed pipe side freezes, the return pipe is used to It is characterized by sucking the fuel in the fuel tank and supplying it to the pump.

Hereinafter, the present invention will be specifically explained based on the illustrated embodiments.

In FIG. 1, 1 is a fuel tank, 2 is a mechanical fuel pump having a well-known structure, and 3 is a vent lily portion 6 upstream of a throttle valve 5 in an intake passage 4, through which fuel is supplied by the fuel pump 2. The carburetor injects from the main nozzle 7 facing the
Reference numeral 8 has a suction port 8a facing the recess 1a provided on the bottom of the fuel tank 1, and the suction side 2 of the fuel pump 2.
A feed pipe 9 is connected to the discharge side 2b of the fuel pump 2, and is a return pipe that returns surplus fuel, that is, the difference between the discharge amount of the fuel pump 2 and the required fuel amount of the carburetor 3, to the fuel tank 1. With a pipe, the discharge port 9a of this return pipe 9
is normally set at a position higher than the suction port 8a of the feed pipe 8 by an appropriate height.

As shown in the figure, in addition to the above-described configuration of the fuel supply system, the present invention includes a bypass passage 1 that interconnects the middle of the feed pipe 8 and the return pipe 9.
0 is provided in the middle of this bypass passage 10,
A first check valve 11 is provided that allows fuel to pass from the return pipe 9 to the feed pipe 8 side and prevents fuel from passing in the opposite direction, and a branch part 1 of the return pipe 9 with the bypass passage 10 is provided.
3, a second check valve 14 is provided on the discharge side of the fuel pump 2 to allow surplus fuel to return from the fuel pump 2 and to prevent fuel from passing in the opposite direction.

The opening pressure of the first check valve 11 is set so that it opens when the suction pressure of the fuel pump 2 exceeds a set value, and the opening pressure of the second check valve 14 is set so that it opens when the discharge pressure of the fuel pump 2 exceeds a set value. Set it to open when the set value is exceeded.

As mentioned above, the bypass passage 10, the first and second
In the structure provided with the check valves 11 and 14, fuel can be supplied to the fuel pump 2 using the return pipe 9 in case of a freezing accident on the feed pipe 8 side in winter or the like.

That is, when moisture mixed in the fuel accumulates in the recess 1a of the fuel tank 1 and freezes, blocking the suction port 8a of the feed pipe 8, the water from the discharge port 9a of the return pipe 9 to the return pipe 9 to the bypass passage 10
(First check valve 11) - The fuel tank 1 is connected to the suction side 2a of the fuel pump 2 in the path of the feed pipe 8.
The fuel pump 2 transfers the supplied fuel to the carburetor 3 by driving the diaphragm 17 in accordance with the rotation of the cam 16 attached to the camshaft 15 driven by the engine. The feed carburetor 3 injects the necessary fuel into the intake passage 4.

Furthermore, when the discharge pressure exceeds the valve opening pressure, the surplus fuel sent to the return pipe 9 flows down to the fuel tank 1 side when the second check valve 14 opens, and is passed through the first check valve at the suction timing of the fuel pump 2. When the valve 11 is opened, the fuel is again fed to the suction side 2a of the fuel pump 2 through the bypass passage 10.

In the above embodiment, the second check valve 14 is provided in the part of the return pipe 9 that is closer to the fuel pump 2 than the branch part 13 with the bypass passage 10. However, as shown in FIG. 14 may be provided at the branch portion 13 of the return pipe 9 with the bypass passage 10. That is, in this case, the valve body 14'a whose valve seat is the communication port 13a of the branch portion 13 that communicates with the discharge side 2b of the fuel pump 2 is urged toward the valve seat by the coil spring 14'b. Just do it like this.

As is clear from the above description, the present invention connects the feed pipe and the return pipe through a bypass passage, allows fuel to pass from the return pipe side to the feed pipe side, and prevents passage in the opposite direction. A fuel supply device characterized in that a first check valve is provided for blocking the flow of fuel, and the return pipe is further provided with a second check valve for blocking fuel from flowing toward the discharge side of the fuel pump from a branching portion with a bypass passage. It provides:

According to the present invention, even if the feed pipe is blocked due to freezing, fuel can be supplied using the return pipe as a feed pipe.
This has the advantage that it can be implemented at low cost, especially for automobiles destined for cold regions.

Furthermore, even if the fuel filter 18 becomes clogged, fuel can be supplied from the return pipe.

[Brief explanation of the drawing]

FIG. 1 is an overall schematic explanatory diagram of a fuel supply system according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram of essential parts showing a modification of the above embodiment. 1...Fuel tank, 2...Fuel pump, 3...
Carburetor, 4... Intake passage, 8... Feed pipe, 9... Return pipe, 10... Bypass passage, 11... First check valve, 13... Branch, 14... Second check valve.

Claims (1)

[Scope of Claim for Utility Model Registration] A fuel supply device comprising a feed pipe that supplies fuel from a fuel tank to an engine using a pump, and a return pipe that returns excess fuel from the pump to the fuel tank, the feed pipe and the return pipe. a first check valve that is interposed in the bypass passage and allows fuel to pass from the return pipe side to the feed pipe side; 1. A fuel supply device comprising: a second check valve interposed in a discharge side portion of the pump for blocking passage of fuel to the discharge side of the pump.