JPH023032B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a fuel pump with a built-in fuel tank,
In particular, the present invention relates to a fuel pump device suitable for fuel transfer.

[Prior art]

Generally, a fuel pump device with a built-in fuel tank is equipped with a pressure control valve. This pressure control valve (hereinafter referred to as a relief valve) is controlled so that the pump pressure does not exceed a certain pressure, is connected to the discharge side of the pump, and is built in the fuel tank together with the pump.

However, in this type of pump device, fuel transfer has become unstable due to changes in outside air temperature and drops in atmospheric pressure experienced when driving at high altitudes, and various problems have occurred.

Hereinafter, the configuration of a conventional fuel pump device is shown in FIG. 1, and its problems will be explained in detail. In the figure, a fuel pump 1 consists of a pump section 2 and an electric motor section 3, and fuel sucked from a strainer 4 of the pump section 2 is transferred to a carburetor (not shown) through a pump discharge port 5, a relief valve 6, and a delivery pipe 10. It is becoming more and more common. The relief valve 6
consists of a valve 7, a spring 8 that applies a force to the valve 7, and a relief valve discharge hole 9. When the pump pressure changes due to fluctuations in the fuel pump load, the valve 7 resists the pressure of the spring 8. The valve is opened and closed so that excess fuel is returned to the fuel tank through the relief valve discharge hole 9, and the fuel pump pressure is always controlled at a constant pressure. In the figure, numerals 11 and 12 indicate parts of the container walls of the fuel tank, with the former indicating the upper shell and the latter indicating the lower shell. Further, the fuel pump 1 itself is held by a bracket 16 fixed to a plate 13, and the plate 13 is connected to the upper shell 1 through a gasket 14.
It is fixed at 1. In addition, numeral 15 in the figure indicates the fuel liquid level (see Japanese Patent Laid-Open No. 56-66446).

In such a configuration, the fuel tank can be considered completely airtight, albeit with a safety valve. Therefore, when the outside temperature rises, the evaporation of the fuel in the fuel tank becomes active, and the pressure in the tank increases by 0.3 kg/kg.
It can be as large as ^cm2 . When the tank internal pressure increases, the tank internal pressure is applied to the valve 7 of the relief valve 6, which means that the fuel pump discharge pressure appears to increase, and the liquid level in the float chamber of the carburetor example (not shown) rises, which can lead to overflow, etc. It may cause trouble. On the other hand, the same is true when driving at high altitudes; the pressure on the carburetor side is below atmospheric pressure due to the high altitude, but on the other hand, the pressure inside the fuel tank is maintained at higher pressure due to atmospheric pressure or vapor pressure. Therefore, the pressure difference increases, and even in such a case, the problem of overflow of the float chamber occurs as described above. On the other hand, if the pressure of the relief valve is adjusted to prevent the above-mentioned troubles, the amount of fuel transferred may be insufficient and a so-called breathing phenomenon may occur during high-speed driving.

In addition, as shown in FIG. 1, the relief valve 6
When the valve is opened, the surplus flow of fuel is discharged from the relief valve discharge hole 9, but the sound of collision between this surplus flow and the fuel liquid level can be heard from the rear seat.
It was very jarring.

[Purpose of the invention]

An object of the present invention is to provide a fuel pump device that allows a vehicle to run stably even under changes in outside temperature or atmospheric pressure.

[Summary of the invention]

In order to achieve such an objective, the present invention
A fuel pump device comprising a fuel pump submerged in a sealed fuel tank, and a pressure control valve located in the fuel tank and connected to a discharge side of the fuel pump for controlling fuel discharge pressure, The pressure control valve is configured such that a spring presses a valve body that blocks the return passage, and opens the pressing surface of the valve body directly to the atmosphere, and when the discharge pressure of the fuel pump exceeds a predetermined value. The valve body is opened and closed depending on the difference between the fuel discharge pressure and the atmospheric pressure, and excess fuel is circulated through the return passage.

[Embodiments of the invention]

Hereinafter, the present invention will be explained based on examples.

FIG. 2 is an embodiment of the present invention, and shows a sectional view of a fuel pump device attached to a fuel tank. The fuel discharged by the fuel pump 1 passes through the rubber hose 5a from the pump discharge hole 5, passes through the high-pressure side passage 19 of the relief valve 6, the relief valve discharge hole 20, the rubber hose 20a, and the delivery pipe 10, and is pumped to a carburetor (not shown). It's becoming like that. The valve 22 of the relief valve 6 has a diaphragm structure, as shown in detail in FIG. 3, and consists of a valve body 23 and a diaphragm 24 attached around the valve body 23. ing. This diaphragm 24 is made of, for example, fluorine rubber.
Made of fluorosilicone, etc. The above valve body 23
is normally brought into contact with the opening of the return pipe 25 by a spring 8. During fuel transfer, the valve body 23 opens according to the pump pressure, thereby controlling the pump discharge pressure to a constant pressure at all times. Excess fuel flowing into the fuel tank is returned to the fuel tank via the return passage 21. In this case, the tip of the return passage 21 is constructed so that it is always submerged below the liquid level even when the fuel liquid level 15 in the fuel tank is at its lowest level (see FIG. 2).

Also, between the left and right sides of the valve 22 is a valve body 2.
3. Complete airtightness is maintained by the diaphragm 24. Then, the valve body 23 and the diaphragm 2
As shown in FIG. 2, the low pressure chamber 26 partitioned by
It is communicated with the atmosphere via an air breather pipe 18. Therefore, the low pressure chamber 26 is not affected by the atmosphere inside the fuel tank. Therefore,
The amount of fuel transferred is determined only by the discharge pressure of the fuel pump, and is not influenced by the pressure in the fuel tank described above.

As explained above, the valve 22 made of a diaphragm in the relief valve 6 is configured so that the discharge pressure of the fuel pump is applied to one side and the atmospheric pressure is applied to the other side, so when the fuel is transferred due to temperature changes, No pressure changes are observed.
In other words, fuel can always be transferred at a constant pressure regardless of the outside temperature. Therefore, since the liquid level in the float chamber on the carburetor side is also under atmospheric pressure, the phenomenon of overflow of the float chamber as described above does not occur. In addition, even when the atmospheric pressure drops to 1 atm or less when driving at high altitudes, it is not affected by the internal pressure of the fuel tank.
Stable fuel transfer is always possible. moreover,
Excess fuel that is returned to the tank as a result of the pressure control of the relief valve is returned below the fuel surface through the return passage, which completely eliminates the collision noise caused by surplus fuel falling onto the liquid surface. The unpleasant noises that were previously heard in the back seat are now gone, making it possible to eliminate one of the sources of noise while driving.

〔Effect of the invention〕

As is clear from the above description, the present invention eliminates problems in fuel transfer caused by changes in outside temperature or atmospheric pressure, and enables stable running of a vehicle.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of a conventional fuel pump device, FIG. 2 is a block diagram showing an embodiment of a fuel pump device according to the present invention, and FIG. 3 is a block diagram showing an embodiment of a fuel pump device according to the present invention. FIG. 3 is a cross-sectional view showing one embodiment. DESCRIPTION OF SYMBOLS 1...Fuel pump, 6...Pressure control valve, 7...Valve, 8...Spring, 9...Relief valve discharge hole, 15
...Low pressure side passage, 18...Air breather pipe, 21
...Return passage, 22...Valve, 23...Valve body, 2
4...Diaphragm, 25...Return pipe, 26
...Low pressure chamber, 27...Low pressure side passage.

Claims (1)

[Claims] 1. A fuel pump device comprising a fuel pump submerged in a sealed fuel tank, and a pressure control valve located in the fuel tank and connected to the discharge side of the fuel pump for controlling fuel discharge pressure. , the pressure control valve is configured such that a spring presses a valve body that blocks the return passage, and a pressing surface of the valve body is directly exposed to the atmosphere, and when the discharge pressure of the fuel pump exceeds a predetermined value, The fuel pump device is characterized in that the valve body is opened and closed depending on the difference between the fuel discharge pressure and the atmospheric pressure, and excess fuel is circulated through the return passage.