JPH0474558B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a turbine-type fuel pump used in an internal combustion engine for an automobile, and particularly to its vapor removal structure.

<Prior art> In recent years, in internal combustion engines for automobiles, turbine-type fuel pumps (non-positive displacement Circumferential flow pumps) tend to be used (see Utility Model Application No. 141392-1980, etc.).

As shown in FIGS. 3 and 4, this turbine-type fuel pump includes an impeller 4 which is rotated in the direction of arrow A in the drawing by an electric motor (not shown) inside the pump housing 1 around a fixed shaft 2 via a joint 3. Accordingly, by the action of the groove 4a formed in the outer periphery of the impeller 4, fuel is sucked in from the suction port 5, and is discharged from the discharge port 7 via the fuel flow path 6.

In addition, when restarting under high fuel temperature conditions, vapor is generated inside the pump, and if the amount of vapor generated is large, the discharge flow rate will be reduced. A hole 8 is provided,
The vapor generated within the pump is allowed to escape into the fuel tank through this vapor vent hole 8.

<Problems to be Solved by the Invention> Incidentally, for the vapor removal effect of the vapor removal hole, it is better to arrange the vapor removal hole near the discharge port where the fuel pressure is high, but in this case, the vapor generation can be prevented. When the temperature is low, the amount of fuel discharged from the vapor vent hole increases, and the pump efficiency at low temperatures deteriorates. For this reason, conventionally, in order to prevent deterioration of characteristics at low temperatures, a small diameter (for example, about 0.7 to 1.4 mm in diameter) vapor removal hole is provided near the suction port where the fuel pressure is low, so that the vapor removal effect is sufficient. I couldn't say that.

The present invention was made in view of the above circumstances, and
It is an object of the present invention to provide a turbine-type fuel pump that maintains pump efficiency at low temperatures and provides sufficient vapor removal action at high temperatures.

<Means for Solving the Problems> For this reason, in the present invention, the vapor extraction hole is constituted by an aggregate of a plurality of holes arranged close to each other along the fuel flow path.

<Function> According to the above configuration, the vapor extraction hole is an aggregate of a plurality of holes, that is, a plurality of holes having a smaller diameter than the conventional hole (larger than the vapor core) are provided close to each other along the fuel flow path, The total opening cross-sectional area of each hole is formed to be approximately the same as the opening cross-sectional area of one conventional vapor extraction hole. Interference is reduced and the vapor removal effect is improved. Further, since the holes are arranged close to each other and the fuel pressure in each hole is approximately equal, the amount of fuel leakage can be suppressed to approximately the same amount as in the past, and pump efficiency at low temperatures is not impaired.

<Example> Hereinafter, an example of the present invention will be described in detail based on the drawings. Incidentally, the same parts as in the prior art are given the same reference numerals, and the description thereof will be omitted.

In FIG. 1 showing this embodiment, the vapor vent holes of this embodiment include a plurality of vapor vent holes 11A and 11B, for example, two vapor vent holes 11A and 11B arranged close to each other along the fuel flow path 6.
It is made up of a collection of.

To be more specific, two parts are placed close to each other along the fuel flow path 6 at substantially the same position as the conventional one near the suction port 5.
Vapor extraction holes 11A are dispersed in multiple locations and have a smaller diameter than the conventional vapor extraction holes 8 (larger than the vapor core).
11B.

The diameter of each vapor extraction hole 11A, 11B is formed so that the sum of the opening cross-sectional areas of each vapor extraction hole 11A, 11B is approximately equal to the opening cross-sectional area of one conventional vapor extraction hole 8. For example, when the diameter of the conventional vapor extraction hole 8 is 1.4 mm, the diameter of each vapor extraction hole 11A, 11B is set to 1.0 mm. Further, the vapor extraction holes 11A and 11B are provided within a range of 20 degrees in terms of center angle (indicated by θ in the figure).

According to this configuration, by providing the vapor extraction holes 11A and 11B with smaller diameters than in the past, interference between the vapors is reduced compared to the conventional one, and the vapor cannot be discharged through the vapor extraction hole 11A on the upstream side. Since the vapor can be discharged from the vapor extraction hole 11B on the downstream side, the vapor extraction effect can be improved. Furthermore, two vapor extraction holes 11A,
11B are placed close to each other in substantially the same position as in the past, the fuel pressure in each vapor vent hole 11A and 11B is substantially the same, and the sum of the cross-sectional areas of both openings is the same as in the past. The amount of fuel leaked can be suppressed to approximately the same amount as before, and pump efficiency at low temperatures is not impaired.

FIG. 2 shows a comparison of the vapor removal effects of this embodiment and the conventional example, and the area above each straight line in the figure shows the region where vapor removal is performed well.

According to this, at the same pump internal pressure, the region where the vapor removal effect is better in this embodiment (indicated by the chain line) is shifted to the higher temperature side compared to the conventional example (indicated by the solid line), so the vapor removal effect is shifted to the higher temperature side. It is clear that the punching effect is improved.

<Effects of the Invention> As described above, according to the present invention, the vapor removal action at high temperatures can be improved without impairing the pump efficiency at low temperatures, and the discharge flow rate characteristics at high temperatures can be improved.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a main part of an embodiment of the present invention, Fig.
The figure is a diagram comparing the effect of vapor removal between the above embodiment and the conventional example, Fig. 3 is a cross-sectional view of a turbine-type fuel pump showing the conventional example (-cross-sectional view of Fig. 4), A cross-sectional view of the figure is shown. 1... Pump housing, 4... Impeller, 5
...Suction port, 6...Fuel flow path, 7...Discharge port, 1
1A, 11B...Vapor extraction hole.

Claims (1)

[Claims] 1. In a turbine-type fuel pump having a vapor vent hole in the fuel flow path from the suction port to the discharge port, the vapor vent hole is configured as an aggregate of a plurality of holes arranged close to each other along the fuel flow path. Features a turbine-type fuel pump.