Fuel Pump

Abstract

Disclosed is a fuel pump which is embodied as a side channel pump and is used for conveying fuel into a fuel reservoir of a motor vehicle, and in which a partially annular duct (13) that extends to a discharge duct (8) is configured in a continually expanding manner. A partially annular duct (12) that is connected to an intake duct (7) tapers in the direction of flow. Blade chambers (10) that are disposed within an impeller (6) form a conveying chamber (14) along with the partially annular ducts (12, 13). Said conveying chamber (14) extends from the intake duct (7) to the discharge duct (8) and is provided with a constant cross section such that the impeller (6) is continuously penetrated by a flow.

Description

BACKGROUND OF THE INVENTION

The invention relates to a fuel pump for delivering fuel into a fuel tank of a motor vehicle, having a driven impeller rotating in a housing, with rings of guide blades defining blade chambers arranged on both end faces of the impeller, opposing blade chambers being connected to one another, with partially annular ducts, which are arranged in the area of the guide blades in an inlet-side housing part and in an outlet-side housing part and which together with the blade chambers form a delivery chamber for delivering a liquid from an inlet duct to an outlet duct, one of the partially annular ducts being connected to the inlet duct and the other, the opposing partially annular duct, being connected to the outlet duct.

Such fuel pumps are known as peripheral or side-channel pumps and are often used in the fuel tanks of present-day motor vehicles. The partially annular ducts extend over an angular range of approximately 300 to 330°.

A disadvantage of the known fuel pumps is that vortices occur in the area of the blade chambers as the delivered liquid flows over. These vortices lead to a low efficiency of the fuel pump and lead, particularly when delivering hot fuel, to gassing of the fuel. The gassing leads to a further reduction in the efficiency of the fuel pump.

BRIEF DESCRIPTION OF THE INVENTION

The object of the invention is to design a fuel pump of the type described in the introductory part so that it has a maximum possible efficiency.

According to the invention this object is achieved in that the partially annular duct in the inlet-side housing part continuously narrows away from the inlet duct and/or the partially annular duct in the outlet-side housing part continuously widens toward the outlet duct, and that the continuous narrowing or widening extends over at least 80% of the length of the corresponding partially annular duct.

This design allows the liquid being delivered to be continuously transferred from the partially annular duct in the inlet-side housing part to the partially annular duct in the outlet-side housing part. This also makes it possible to generate a uniform rise in pressure increasing toward the outlet duct in the two partially annular housing parts. This means that there is a uniform flow through the opposing blade chambers as they move from the inlet duct to the outlet duct. This serves to prevent the rate of flow as the liquid flows over from one blade chamber into the opposing blade chambers increasing the closer these blade chambers get to the outlet duct, as is the case in the known fuel pump. The fuel pump according to the invention therefore has an especially high efficiency.

Abrupt flow variations in the delivery chamber lead to gassing of the fuel, particularly when the fuel being delivered is at high temperature. According to another advantageous further embodiment of the invention such abrupt flow changes are readily prevented if the narrowing or widening is continuous over the proposed area of the length of the partially annular duct.

According to another advantageous further embodiment of the invention the narrowing or widening of the partially annular ducts is particularly easy to configure if at least one of the partially annular ducts is of wedge-shaped design in a section along the delivery chamber.

In order to further reduce pressure fluctuations in the delivery chamber it is of help, according to another advantageous further embodiment of the invention, if the delivery chamber has substantially the same cross-section at any point, the cross-section of the partially annular duct in the inlet-side housing part being larger in proximity to the inlet duct than the cross-section of the partially annular duct in the outlet-side housing part.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention permits numerous embodiments. In order to further illustrate its basic principle, one such embodiment is represented in the drawing and is described below. In the drawing:

FIG. 1 shows a fuel delivery unit for a motor vehicle having a fuel pump according to the invention,

FIG. 2 shows a tangential, sectional representation through the fuel pump in the area of a delivery chamber.

FIG. 1 shows a fuel delivery unit intended to be arranged in a fuel tank of a motor vehicle and having a housing 1 and a fuel pump 3 in the form of a side-channel pump driven by an electric motor 2. The fuel pump 3 has an impeller 6 arranged between an inlet-side housing part 4 and an outlet-side housing part 5. An inlet duct 7 is arranged in the inlet-side housing part 4 and an outlet duct 8 in the outlet-side housing part 5. The impeller 6 is fixed on a shaft 9 of the electric motor 2. The fuel pump 3 has opposing rings of guide blades 11 defining blade chambers 10 on both end faces of the impeller 6. The housing parts 4, 5 each have a partially annular duct 12, 13 in the area of the blade chambers 10. The partially annular ducts 12, 13 together with the blade chambers 10 form a delivery chamber 14 leading from the inlet duct 7 through the impeller 6 to the outlet duct 8. For the purpose of simplification, the inlet duct 7 and the outlet duct 8 are shown turned into the plane of projection. As a rule, the delivery chamber 14 extends over an angular range of approximately 300 to 330°. As the impeller 6 rotates the guide blades 11 produce a circulatory flow, running transversely to the direction of movement of the guide blades 11, in the delivery chamber 14. In so doing the delivered fuel flows over from the inlet-side housing part 4 to the outlet-side housing part 5 through the interconnected blade chambers 10.

FIG. 2, in a tangential section through the fuel pump in FIG. 1 in the area of the delivery chamber 14, shows that the partially annular duct 12 arranged in the inlet-side housing part 4 narrows away from the inlet duct 7, viewed in the direction of flow. The partially annular duct 13 arranged in the outlet-side housing part 5 furthermore widens toward the outlet duct 8 viewed in the direction of flow. In order to show this more clearly the fuel flows and the direction of movement of the impeller 6 are identified by arrows in the drawing. The widening and narrowing extend virtually over the entire length of the partially annular ducts 12, 13 and each virtually have a wedge shape. The partially annular ducts 12, 13 widen and narrow to the same degree, so that over the whole area of the partially annular ducts 12, 13 the delivery chamber 14 has substantially the same cross-section.

Claims

1. A fuel pump for delivering fuel into a fuel tank of a motor vehicle, having a driven impeller rotating in a housing, with rings of guide blades defining blade chambers arranged on both end faces of the impeller, opposing blade chambers being connected to one another, with partially annular ducts, which are arranged in the area of the guide blades in an inlet-side housing part and in an outlet-side housing part and which together with the blade chambers form a delivery chamber for delivering a liquid from an inlet duct to an outlet duct, one of the partially annular ducts being connected to the inlet duct and the other, the opposing partially annular duct, being connected to the outlet duct, characterized in that the partially annular duct (12) in the inlet-side housing part (4) narrows away from the inlet duct (7) and/or the partially annular duct (13) in the outlet-side housing part (5) widens toward the outlet duct (8), and that the narrowing or widening extends over at least 80% of the length of the corresponding partially annular duct (12, 13).

2. The fuel pump as claimed in claim 1, characterized in that the narrowing or widening is continuous over the proposed area of the length of the partially annular duct (12, 13).

3. The fuel pump as claimed in claim 1 or 2, characterized in that at least one of the partially annular ducts (12, 13) is of wedge-shaped design in a section along the delivery chamber.

4. The fuel pump as defined in claim 1, characterized in that the delivery chamber (14) has substantially the same cross-section at any point, the cross-section of the partially annular duct (12) in the inlet-side housing part (4) being larger in proximity to the inlet duct (7) than the cross-section of the partially annular duct (13) in the outlet-side housing part (5).