Fuel Pump and Fuel Feed System for an Internal Combustion Engine of a Motor Vehicle Having a Fuel Pump

Abstract

In a fuel pump in the form of a side-channel pump for a motor vehicle two partially annular ducts (21, 22) concentrically enclosing one another are connected to one another via a connecting duct (29). Connections (33, 34) of the connecting duct (29) to the partially annular ducts (21, 22) are laid so that at a rated speed of the fuel pump the same pressure prevails in each of them. If the speed falls below the rated speed, fuel passes from the radially outer, partially annular duct (22) into the radially inner, partially annular duct (21). A sufficient delivery capacity through the radially inner, partially annular duct (21) is thereby ensured.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

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

FIG. 1 shows a schematic representation of a fuel feed system having a fuel pump according to the invention.

FIG. 2 shows a section through the fuel pump in FIG. 1 along the line II-II.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a schematic representation of a fuel feed system 1 for an internal combustion engine 2 of a motor vehicle having a feed unit 4 arranged in a fuel tank 3. The feed unit 4 has a fuel pump 6, arranged in a swirl pot 5, having a pump stage 8 driven by an electric motor 7. The electric motor 7 is supplied with electrical current via a control device 9. Fuel delivered by the fuel pump 6 passes via a flow line 10 to the internal combustion engine 2. The flow line 10 and electrical leads 11 of the electric motor 7 are led through a flange 12 introduced into the fuel tank 3.

The pump stage 8 takes the form of a side-channel pump and has an impeller 15, rotatably arranged between two casing parts 13, 14, and two delivery chambers 16, 17.

The impeller 15 is rotationally locked on a shaft 18 of the electric motor 7 and has two rings of guide vanes 19, 20 concentrically enclosing one another and defining blade chambers. The blade chambers together with partially annular ducts 21, 22 arranged opposite in the casing parts 13, 14 form the delivery chambers 16, 17. The radially inner delivery chamber 16 delivers fuel from the swirl pot 5 to a jet pump 23, whilst the radially outer delivery chamber 17 delivers fuel from the swirl pot 5 through the electric motor 7 into the flow line 10. The jet pump 23 draws fuel from the fuel tank 3 via a prefilter 24 and delivers this into the swirl pot 5. The delivery chambers 16, 17 each pass through the impeller 15 and therefore have partially annular ducts 21, 22 arranged in each of the casing parts 13, 14. In FIG. 1, for the purpose of illustration, inlets 25, 26 and outlets 27, 28 of the delivery chambers 16, 17 in the casing parts 13, 14 are shown turned into the plane of the drawing. In actual fact the partially annular ducts 21, 22 extend over an angular range of up to 340°.

FIG. 2 shows one of the casing parts 14 of the pump stage 8 of the fuel pump 6 in FIG. 1. This clearly shows the partially annular ducts 21, 22 concentrically enclosing one another, which are arranged facing the rings of the guide vanes 19, 20 of the impeller 15 represented in FIG. 1. The direction of rotation of the impeller 15 is identified by an arrow. FIG. 2 furthermore shows that the partially annular ducts 21, 22 are connected to one another via a connecting duct 29. The connecting duct 29 takes the form of a groove which is arranged in the casing part 14 and is deeper than it is wide. The connecting duct 29 has an initial section 30 connected to the outer partially annular duct 22, and a terminal section 31 opening into the inner partially annular duct 21. The initial section 30 and the terminal section 31 are connected to one another by a middle section 32 arranged parallel to the partially annular ducts 21, 22. The initial section 30 is inclined by the angle α and the terminal section 31 is inclined by the angle β to the straight line taken through the axis of rotation of the impeller 15. The angles α and β are in each case 45°, for example.

The connecting duct 29 is connected to the partially annular ducts 21, 22 in such a way that at a rated speed of the impeller 15 the same pressure prevails at connections 33, 34 of the connecting duct 29 to the partially annular ducts 21, 22. A pressure equilibrium, which prevents any flow of fuel, thereby prevails in the connecting duct 29. If the speed of the impeller 15 falls below the rated speed, however, the feed pressures in the delivery chambers 16, 17 and hence in the partially annular ducts 21, 22 will also fall. In the radially inner, partially annular duct 21, however, the fall in pressure is much more pronounced than in the radially outer, partially annular duct 22. Such a fall in pressure would mean, however, that the jet pump 23 would no longer be reliably supplied with fuel as propellant. The connecting duct 29 remedies this by diverting fuel from the radially outer delivery chamber 17 in the event of a fall in pressure in the radially inner delivery chamber 16, thereby maintaining the intended pressure in the radially inner delivery chamber 16. The fuel feed system 1 thereby allows the power output of the electric motor 7 to be controlled by the control device 9 according to the fuel consumption of the internal combustion engine 2.

Claims

1. A fuel pump having a driven impeller (15) facing a casing part (14), with rings of guide vanes arranged in the impeller concentrically enclosing one another and defining blade chambers, with partially annular fuel feed ducts (21, 22) facing the rings of guide vanes in the casing part, and with outlet ducts connected to the partially annular ducts, the rings of the blade chambers and the partially annular ducts forming a radially inner delivery chamber and a radially outer delivery chamber, characterized in that a radially outer delivery chamber (17) is connected to a radially inner delivery chamber (16) via a connecting duct (29).

2. The fuel pump as claimed in claim 1, characterized in that the connecting duct (29) is arranged in the casing part (14) and connects partially annular ducts (21, 22).

3. The fuel pump as claimed in claim 1 or 2, characterized in that the connecting duct (29) takes the form of a groove arranged in the casing part (14).

4. The fuel pump as defined in claim 1, characterized in that the connecting duct (29) points away from the radially outer delivery chamber (17) towards the radially inner delivery chamber (16) viewed in the direction of rotation of the impeller (15).

5. The fuel pump as defined in claim 1, characterized in that connections (33, 34) of the connecting duct (29) connect to the radially inner and the radially outer delivery chambers (16, 17) are laid so that at a rated speed of the impeller (15) the same pressure prevails on both connections (33, 34).

6. The fuel pump as defined in claim 2, characterized in that an initial section (30) of the connecting duct (29) connected to the radially outer, partially annular duct (22) is inclined by a designated angle α to the straight line taken through the axis of rotation of the impeller (15).

7. The fuel pump as defined in claim 2, characterized in that a terminal section (31) of the connecting duct (29) opening into the radially inner, partially annular duct (21) is inclined by a designated angle β to the straight line taken through the axis of rotation of the impeller (15).

8. The fuel pump as defined in claim 6 or 7, characterized in that the angle α and/or the angle β is/are approximately 45°.

9. The fuel pump as defined in claim 2, characterized in that the connecting duct (29) has a middle section (32) arranged concentrically between the partially annular ducts (21, 22).

10. The fuel pump as defined in claim 1, characterized in that the impeller (15) has a smooth surface in its area facing the connecting duct (29).

11. The fuel pump as defined in claim 1, characterized in that the connecting duct (29) is in the form of a groove is deeper than it is wide.

12. A fuel feed system for an internal combustion engine of a motor vehicle having a fuel pump with an impeller (15) for drawing fuel from a fuel tank and delivering the fuel to the internal combustion engine, characterized in that the pump has a radially outer delivery chamber (17) that is connected to the internal combustion engine (2) and a radially inner delivery chamber (16) that is connected to a jet pump (23) arranged inside a fuel tank (3).

13. The fuel feed system as defined in claim 12, characterized by a control device for regulating the power output of an electric motor (7) driving the impeller (15) as a function of the fuel demand of the internal combustion engine (2).