JPS611890A - Fuel supply pump - Google Patents

Abstract

PURPOSE:To improve intake property by providing a vent valve which exhausts air and fuel gas rapidly to the outside of a case and a pump casing and seals the case and pump casing as soon as the inside is filled with fuel. CONSTITUTION:When an armature 3 is rotated, air or fuel gas in a case 11 passes around a valve body 13 of a vent valve provided in a discharge portion 15 and is ejected easily to the outside of the case 11 so that the inside is rapidly filled with liquefied fuel. When the liquefied fuel is going to pass around a valve body 13, the fluid resistance becomes larger than the weight of the valve body 13 to push up the valve body 13 in the direction of liquefied fuel flow, i.e. upward and close a vent hole 14. The liquefied fuel is of fluid having approximately non-compressive property so that pressure in the case 11 is increased for an instant and thereafter the valve body 13 is stabilized by differential pressure between the inside and outside of the case 11 to close the vent hole 14. Thus, the loss of leakage is reduced and the early intake property can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a fuel supply pump, and particularly to an in-tank fuel supply pump suitable for an electronically controlled fuel injection device for an automobile engine.

[Background of the invention]

A conventionally known in-tank fuel supply pump has a schematic structure as shown in Fig. 1 of Japanese Utility Model Application No. 58-161161, which is closed by an upper cover with a discharge port and a lower cover with an intake port. It consists of a cylindrical case, and a pump rotor that is installed inside the case and whose upper and lower ends of its rotating shaft are supported by bearings on the upper and lower covers, respectively. A body is provided which forms a pump casing with a lid. However, when attempting to pump fuel using such an electric fuel pump.

The inside of the case is completely sealed, so even though the electric fuel pump is immersed in the fuel liquid, there is no possibility that fuel will enter the pump casing due to internal air pressure or fuel air pressure. Therefore, even if the electric motor is rotated, the pump rotor idles and no fuel is pumped out. This phenomenon is more pronounced in pressure type pumps than in positive displacement type pumps.

For this reason, in the case of a Wesco pump, a method is generally adopted in which small diameter air circulation holes are provided in each of the lower cover and the impeller to facilitate the flow of fuel into the case, that is, into the pump casing. However, in this method, it is not preferable to provide the air circulation hole at a position where the fuel pressure is completely increased because it will lead to an increase in leakage loss, and if it is provided in the pump casing in the middle of the pressure increase, there are disadvantages such as insufficient effect. There was.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide an in-tank fuel supply pump that has low leakage loss and excellent initial suction characteristics.

[Summary of the invention]

The present invention focuses on the fact that what impedes the initial suction performance of the fuel supply pump is the air or fuel vapor inside the case and pump casing, and promptly discharges these gases to the outside of the case and pump casing. At the same time, a vent valve is provided to seal the case and pump casing, thereby ensuring good suction characteristics without reducing efficiency.

[Embodiments of the invention]

A first embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a sectional view of the embodiment according to claim 3, and FIG. 2 is a partially enlarged view of the vent valve.

The figure shows an electric fuel supply pump with a cylindrical case 1.
A filter 8 is installed at the bottom of the fuel tank to filter the fuel in the fuel tank.
A pump unit 6 that pumps fuel into the case 11 via a commutator motor 3 that is provided inside the case 11 and drives the pump unit 6, and a discharge unit 15 that is provided at the top of the case 11 and guides the pumped fuel to the outside. It is composed of.

The pump section 6 is of the Wesco type, and includes a suction side plate 18 having a fuel suction port 5 of a filter 8 on its peripheral edge, an impeller 6, and a discharge side plate 4. Suction side plate 1
8 and the discharge side plate 4 are fixed by caulking the entire lower circumference of the case 11.

The impeller 6 is fixed in the rotational direction to the armature shaft 7 via serrations, and rotates integrally with the armature 3.

The commutator motor consists of two semi-cylindrical permanent magnets 10 fixed to the inner surface of a case 11, an armature 3 located at a predetermined gap, and a commutator 2 fixed coaxially with the armature 3.
and a synthetic resin discharge part 1 provided at the top of the case 11.
5, and a brush 1 which is pressed against the commutator by a spring (not shown) and supplies current to the armature 3.

The discharge part 15 is fixed by caulking the entire circumference of the upper circumference of the case 11. This discharge portion 15 has a check valve 16 that is pressed downward by a spring (not shown).

Further, the discharge portion 15 has a vent valve whose detailed shape is shown in FIG. The air release valve has a spherical valve body 13 made of rubber, a valve seat 15a above the valve body 15a, and a retainer 1 below the valve body 13.
It has 2. The valve body includes a retainer 12 and a valve seat 15a.
You can move freely between the two.・□ The fuel supply pump of this embodiment is installed by being immersed in the fuel tank so that the discharge part 15 faces upward and the pump part 6 faces the other direction.

When the armature 3 is rotated in the above configuration, the air or fuel vapor inside the case 11 passes around the valve body 13 of the air vent valve and is easily released to the outside of the case 11, and the inside is quickly filled with liquid fuel. filled with.

When liquid fuel tries to pass around the valve body 13,
The fluid resistance is larger than the weight of the valve body 13, and the valve body 13
in the flow direction of the liquid fuel, that is, upward, and open the air vent hole 1.
4 will be closed. Since liquid fuel is considered to be a substantially incompressible fluid, the pressure inside the case 11 is increased instantaneously. After increasing the pressure, the valve body 13
The air vent hole 14 is stably sealed.

The above operation of the valve body 13 is due to the fact that the fluid resistance of the liquid is much greater than the fluid resistance of the gas. As is well known, fluid resistance is proportional to the viscosity of the fluid. Therefore, the weight of the valve body 13 is greater than the fluid resistance due to the flow of gases such as air and fuel vapor, but is smaller than that of liquid fuel.

The Wesco type fuel supply pump of this embodiment quickly increases the fuel discharge pressure even when the impeller 6 is not filled with liquid fuel, for example, during the first C excitation after refueling after the fuel has run out. Moreover, it is highly efficient with no leakage loss after boosting the voltage.

FIG. 3 is an embodiment of claim 4, in which the valve body 1
A spring 19 is provided between the valve seat 15a and the valve seat 15a, and the other structure is the same as that of the first embodiment. In this structure, the valve body 1
The movement of No. 3 is more stable than that of the first example. Furthermore, by appropriately setting the spring pressure, the vertical direction of the air vent valve can be freely oriented, which has the effect of increasing the degree of freedom in position setting.

〔Effect of the invention〕

According to the present invention, the air or fuel vapor inside the case can be quickly discharged, and after discharge, the inside of the case can be sealed, thereby providing an in-tank fuel supply pump that has quick initial suction characteristics and has low leakage loss. I can do it.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of an embodiment of claim 3;
The figure is a partial enlarged view of the air vent valve section, and FIG. 3 is a partial enlarged view of the air vent valve section of the embodiment according to claim 4. 3... Armature, 4... Discharge side plate, 6... Impeller, 12... Retainer, 13... Valve body, 15...
・Discharge part, 15a... Valve seat, 18... Suction side plate, 19... Spring.

Claims (1)

[Claims] 1. In a fuel supply pump installed in a fuel tank, the space that is directly exposed to the pressure of the fuel pressurized by the pump section is not closed by the fluid resistance of gases such as air and fuel vapor. , a fuel supply pump characterized in that it is provided with a vent valve that closes according to the fluid resistance of the liquid fuel. 2. The fuel supply pump according to claim 1, wherein the pumping system of the pump section is a pressure type pump. 3. The fuel supply pump according to claim 2, wherein the pressure type pump is a Wesco pump. 4. In claims 1, 2, and 3, the spring pressure is set so that the spring does not close due to the fluid resistance of a gas such as air or fuel vapor, but closes due to the fluid resistance of a liquid. 1. A fuel supply pump characterized by being provided with an air release valve whose movement of a valve body is regulated by a spring.