JP2000227060A - Fuel pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve vapor exhaust property of a fuel pump by nearly separating fuel mixed with vapor into vapor and fuel to individually discharge them. SOLUTION: In a fuel pump having a vapor escape hole 20 communicating from a pump chamber 15 to the inner space of a fuel tank, between the vapor escape hole 20 and the inner space of the fuel tank, a chamber 22 is provided, with reduces pressure of fuel mixed with vapor discharged through the vapor escape hole 20 and smoothes the pressure variation. A plurality of restriction holes 31, 32 are provided between the chamber 22 and the inner space of the fuel tank. The restriction holes 31, 32 are opened on the wall of the chamber 22 with upper and lower positional relation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a fuel pump mainly used for automobiles.

[0002]

2. Description of the Related Art FIGS. 4 to 6 show a conventional example of a fuel pump.
This will be described with reference to FIG. The fuel pump shown in a partially cutaway side view in FIG. 4 includes a substantially cylindrical metal pump housing 2, an electric motor unit 3 disposed on an upper part of the pump housing 2, and a lower end of the pump housing 2. Aluminum die-cast cover member 6 attached to the part
And a pump unit 4 arranged via the pump.
The fuel pump is installed substantially vertically in the internal space of the fuel tank.

The drive shaft 9 of the rotor 8 in the electric motor unit 3 is rotatably supported by the cover member 6 via a bearing 10. An impeller 12 made of synthetic resin is engaged with the lower end of the drive shaft 9. The impeller 12
It has a substantially disk shape and has a plurality of blade grooves (symbols omitted) on its outer peripheral edge.

A pump body 14 made of aluminum die-casting is fixed to the lower end of the pump housing 2 together with the cover member 6 by caulking the lower edge of the pump housing 2. The cover member 6
The impeller 12 is rotatably accommodated between the pump body 14 and the pump body 14.

The cover member 6 and the pump body 14
Is formed with a concave groove (symbol omitted) that forms a substantially C-shaped pump chamber 15 along the outer peripheral portion of the impeller 12. The pump chamber 15 communicates with an inlet port 17 formed in the pump body 14. A filter (not shown) is provided below the inlet port 17. This filter is brought into contact with the bottom of the fuel tank,
The fuel pump is attached to the fuel tank with the top and bottom shown in FIG. The pump chamber 15 is communicated with an internal space 2a of the pump housing 2 through an outlet port (not shown) formed in the cover member 6.

The pump body 14 is formed with a small-diameter vapor escape hole 20 communicating with the pump chamber 15. The vapor escape hole 20 is for removing a vapor in the fuel flowing in the pump chamber 15 and is formed in the pump body 14 by drilling a hole or the like.

In FIG. 5, which shows a partial cross-sectional view of the periphery of the vapor escape hole 20, a chamber 22 is formed in the pump body 14 so as to communicate with the outlet side of the vapor escape hole 20. The chamber 22 has a recess 18 formed by drilling a hole or the like in the pump body 14 with a hole diameter larger than the hole diameter of the vapor escape hole 20, and a metal or resin cover plate 23 is provided at the lower end opening of the recess 18. It is formed by mounting by press fitting or the like.

The pump body 14 has a small-diameter throttle hole 25 penetrating the wall surface of the chamber 22 in a substantially radial direction.
Are formed by drilling holes or the like. Therefore, the chamber 22 communicates with the internal space of the fuel tank through one throttle hole 25. A bottom view of the pump body 14 is shown in FIG.

Next, the operation of the fuel pump configured as described above will be described. The impeller 12 rotates together with the drive shaft 9 as the electric motor unit 3 is driven. Then, the pressure in the pump chamber 15 is increased, so that the fuel in the fuel tank is sucked into the pump chamber 15 from the inlet port 17. Fuel (see solid arrow F in FIG. 5)
After the pressure is increased while flowing through the pump chamber 15, the pressure is sent from the outlet port to the internal space 2 a of the pump housing 2.

At this time, the vapor generated by the rise in the temperature of the internal space of the fuel tank or the vapor generated by the fuel suction action is used as the fuel mixed with the vapor (see the dotted arrow VF in FIG. 5). It is ejected into the chamber 22 through 20. Chamber 2
In 2, the pressure of the fuel mixed with the vapor (VF) is reduced and the pressure fluctuation is smoothed and calmed. Thereafter, the fuel mixed with the vapor (VF) is discharged from the throttle hole 25 into the internal space of the fuel tank.

As a result, the vapor content of the fuel sent from the pump housing 2 to the engine (not shown) is reduced, and the so-called vapor lock phenomenon is prevented. Further, since the fuel mixed with the vapor is discharged from the throttle hole 25 after being calmed down in the chamber 22, the sound of discharging the fuel mixed with the vapor is reduced. In addition, such a fuel pump is
For example, the same applicant previously proposed the actual fairness 6-1407.
No. 3 discloses this.

[0012]

By the way, in recent years, with the increase of the pump flow rate of the fuel pump and the improvement of the pump efficiency, the generation of vapor tends to increase. Therefore, in the above-described fuel pump, the vapor-mixed fuel (VF) in which the vapor and the fuel are mixed is discharged from one throttle hole 25, so that the vapor discharge performance may be insufficient. In addition, when various experiments were conducted, it was found that the vapor-mixed fuel in which the vapor and the fuel were mixed was discharged into the vapor and the fuel separately from the plurality of the throttle holes, rather than being discharged from the single throttle hole 25. It was found that the better the vapor discharge property, the better.

An object of the present invention is to provide a fuel pump capable of improving the vapor discharge performance by roughly separating the fuel mixed with the vapor into the vapor and the fuel and discharging them separately.

[0014]

According to a first aspect of the present invention, there is provided a fuel pump having a vapor escape hole communicating from a pump chamber to an internal space of a fuel tank. A chamber provided between the chamber and an internal space of the fuel tank for reducing the pressure of the vapor-mixed fuel discharged through the vapor relief hole and smoothing the pressure fluctuation. A plurality of throttle holes, wherein the plurality of throttle holes are opened on the wall surface of the chamber in a vertical positional relationship.

[0015] With this configuration, the vapor-mixed fuel generated in the pump chamber is guided into the chamber through the vapor escape hole, so that the pressure is reduced and the pressure fluctuation is smoothed and calmed down. Most of the vapor rising to the upper part is discharged from the upper restriction hole, and most of the fuel accumulated in the lower part of the chamber is discharged from the lower restriction hole. Therefore, the vapor-exhaustability can be improved by roughly separating the fuel mixed with the vapor into the vapor and the fuel and discharging them separately.

According to a second aspect of the present invention, the plurality of throttle holes are a total of a vapor throttle hole near the upper end of the chamber wall and a fuel throttle hole near the lower end of the chamber wall. 2. The fuel pump according to claim 1, wherein the fuel pump has two throttle holes. According to this structure, the vapor floating at the upper end of the chamber is discharged from the vapor restrictor, and the fuel accumulated at the lower end of the chamber is discharged from the fuel restrictor. Properties can be effectively improved.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. Since the fuel pump of the present embodiment is a modification of the conventional example, the modified part will be described in detail, and the parts that are considered to be the same or equivalent to the conventional example will be assigned the same reference numerals. Duplicate description will be omitted. FIG. 1 is a partial sectional view showing a main part of the fuel pump, FIG. 2 is a bottom view of the pump body 14, and FIG.

The pump body 14 has two upper and lower throttle holes 31 and 32, ie, an upper vapor throttle hole 31 and a lower fuel throttle hole 32, which are vertically arranged on the wall surface of the chamber 22, that is, the wall surface of the concave hole 18. It is opened with the positional relationship of. Thus, the vapor throttle hole 31 is provided in the chamber 2.
The fuel restrictor hole 32 is opened near the lower end of the wall surface of the chamber 22.

According to the above-described fuel pump, the vapor generated by the rise in the temperature of the internal space of the fuel tank or the vapor generated by the fuel suction action is used as the fuel mixed with the vapor (see the dotted arrow VF in FIG. 1). 1
4 is ejected into the chamber 22 through the vapor escape hole 20. In the chamber 22, the fuel mixed with the vapor (V
The pressure of F) is reduced and the pressure fluctuation is smoothed and calmed down.

The fuel mixed with vapor (VF) discharged through the vapor escape hole 20 collides with the bottom surface of the chamber 22, that is, the lid plate 23, and moves upward. At this time, since the vapor of the fuel mixed with the vapor has a smaller specific gravity than the fuel, it easily floats on the upper part of the chamber 22 as shown by a virtual arrow V in FIG. As shown by F1, it tends to stay at the lower part of the chamber 22.

The vapor (V) floating above the chamber 22 is discharged from the vapor aperture 31. Further, the fuel (F) accumulated in the lower portion of the chamber 22
1) is discharged from the fuel throttle hole 32. Thereby, the vapor content of the fuel sent from the pump housing 2 to the engine (not shown) is inevitably reduced, and the so-called vapor lock phenomenon is prevented. Also, after the fuel mixed with the vapor is calmed down in the chamber 22, the throttle hole 3
Since the fuel is discharged from the fuel tanks 1 and 32, the sound of discharging fuel mixed with the vapor is reduced.

According to the fuel pump configured as described above, most of the vapor (V) floating on the upper part of the chamber 22 is discharged from the vapor throttle hole 31, and most of the fuel (F1) stored on the lower part of the chamber is discharged. It is discharged from the fuel throttle hole 32. Therefore, the vapor-mixed fuel (VF) is roughly separated into the vapor (V) and the fuel (F1) and separately discharged, whereby the vapor discharge performance can be improved.

Further, the vapor (V) floating at the upper end of the chamber 22 is discharged from the vapor restricting hole 31, and the fuel (F 1) accumulated at the lower end of the chamber 22 is discharged from the fuel restricting hole 32. The vapor discharge performance can be effectively improved by a total of two throttle holes.

The present invention is not limited to the above embodiment, but can be modified without departing from the spirit of the present invention. For example, three or more apertures may be opened on the wall surface of the chamber in a vertical positional relationship. It is effective that the vapor throttle hole 31 is opened near the upper end of the wall surface of the chamber 22, and the fuel throttle hole 32 is effectively opened near the lower end of the wall surface of the chamber 22. However, the vapor throttle hole 31 and the fuel throttle hole 32 only need to be opened on the wall surface of the chamber 22 in a vertical positional relationship, and the opening positions of the chamber 22 in the vertical direction and the circumferential direction are not limited.

[0025]

According to the fuel pump of the present invention, the fuel mixed with the vapor is roughly separated into the vapor and the fuel and discharged separately, so that the vapor discharge performance can be improved.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing a main part of a fuel pump.

FIG. 2 is a bottom view of the pump body.

FIG. 3 is a partially cutaway perspective view of a pump body.

FIG. 4 is a partially cutaway side view of a fuel pump showing a conventional example.

FIG. 5 is a partial sectional view showing a main part.

FIG. 6 is a bottom view of the pump body.

[Explanation of symbols]

 15 Pump room 20 Vapor escape hole 22 Chamber 31 Vapor throttle hole 32 Fuel throttle hole

Claims (2)

[Claims] 1. A fuel pump having a vapor relief hole communicating from a pump chamber to an internal space of a fuel tank, wherein the fuel pump is provided between the vapor relief hole and the internal space of the fuel tank and discharged through the vapor relief hole. And a plurality of throttle holes provided between the chamber and the internal space of the fuel tank, wherein the plurality of throttle holes are provided between the chamber and the internal space of the fuel tank. , A fuel pump that opens on the wall surface of the chamber in a vertical positional relationship. 2. A plurality of throttle holes, a throttle hole for a vapor opening near an upper end of a wall surface of the chamber, and a throttle hole for a fuel opening near a lower end portion of the wall surface of the chamber. The fuel pump according to claim 1, wherein