GB2258694A

GB2258694A - I.c.engine fuel supply and return pipe arrangment.

Info

Publication number: GB2258694A
Application number: GB9117601A
Authority: GB
Inventors: Melvin Coldwell
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1991-08-15
Filing date: 1991-08-15
Publication date: 1993-02-17
Also published as: GB9117601D0

Abstract

Fuel supply to the engine 16 from the tank 10 is through a pipe 20a within a pipe 24a through which fuel returns to the tank. Porous spacer rings (28, Fig. 3) or spacer webs (26, Fig. 4) may locate the pipe 20a within the pipe 24a. <IMAGE>

Description

A FUELLING ARRANGEMENT FOR AN INTERNAL COMBUSTION ENGINE This invention relates to a fuelling arrangement for an internal combustion engine in which there are both fuel feed and fuel return lines extending between the engine and a fuel tank.

This configuration is normally used in an engine (petrol or diesel) employing fuel injection. The fuel feed line is at a relatively high pressure, and the fuel return line at a relatively low pressure. Any rupture of the fuel feed line in particular would have serious consequences, not only because of the spillage of fuel but also because the high pressure in this line may cause any leaking fuel to be expelled in the form of a mist which would be highly combustible. Leakage from return lines is less critical because of the lower pressure level.

According to the present invention, there is provided a fuelling arrangement for an internal combustion engine, the arrangement comprising an engine, a fuel tank, a fuel feed line connecting the tank with the engine, and a fuel return line connecting the engine with the tank, wherein the fuel feed line is fitted inside the return line where the lines extend between the tank and the engine.

The feed and return lines may be formed in a single manufacturing process. For example two concentric tubes could be formed by a single extrusion process.

Alternatively the feed line could simply be threaded through a larger diameter pipe so that the return line is formed in the space within the larger diameter pipe which surrounds the feed line. If necessary, separate spacer members could be used to ensure concentrici-y of the feed line in the outer pipe.

By placing the high pressure feed line inside the low pressure return line, the advantage is obtained that the high pressure feed line is extremely unlikely to be damaged.

Any damage to the low pressure return line will be considerably less serious than corresponding damage to the high pressure feed line. Any failure in the high pressure feed line itself, without damage to the outer pipe, would merely result in leakage of fuel into the return line.

The invention will now be further described, by way of example, with reference to the accompanying drawing in which Figure 1 is a schematic view showing a fuelling arrangement in accordance with the prior art; Figure 2 is a schematic arrangement corresponding to Figure 1 but showing a fuelling arrangement in accordance with the invention; and Figures 3, 4 and 5 show three alternative cross sections through the fuel line of Figure 2.

Figure 1 shows a fuelling arrangement consisting of a fuel tank lo, a pump 12 and a fuel rail 14. The rail is mounted on an engine indicated by phantom lines 16, and feeds fuel to four injectors 18.

The pump 12 (which may be an in-tank fuel pump) pumps fuel from the tank 10 along the fuel feed line 20 to the fuel rail 14. A fuel filter (not shown) may be associated with the pump 12 or may be otherwise included in the feed line 20. Some of the fuel passes through the injectors 18 and is consumed by the engine, but a proportion of the fuel passes through the fuel rail and to a pressure regulator 22 which maintains the pressure in the (high pressure) feed line 20.

Downstream of the regulator 22, the fuel passes into a low pressure return line 24 which leads back to the tank 10.

It will be appreciated that the fuel tank 10 is usually located at one end of the vehicle and the engine 16 is at the other end of the vehicle. Therefore the fuel lines 20, 24 have to traverse the length of the vehicle.

Conventionally they run side by side.

Figure 2 shows an arrangement in accordance with the invention where two pipes, one within the other, form the fuel return line 24a and the feed line 20a. The feed line is provided by the inner pipe; the return line is provided by the annular passage outside the inner pipe and inside the outer pipe. The two pipes extend one within the other from a position where they leave the area of the engine right up to a position where they approach the area of the fuel tank 10. The two pipes will however be separately connected to the fuel rail 14 and to the tank 10, in their conventional positions.

In an alternative arrangement, the two pipes may be connected to the fuel rail and/or the fuel pump by a single connector which has concentric passages for the feed and return lines.

Figures 3, 4 and 5 show three alternative fuel line cross sections on the section III-III. In Figure 5 the fuel line 20a is unrestrained within the outer pipe 24a which forms the outer boundary of the fuel return line. In Figure 4, the fuel feed line 20b is supported centrally within the outer pipe 24b by support webs 26 which do not obstruct the flow cross section between the two pipes.

In Figure 3, the pipes 20c and 24c are supported concentrically by means of a porous spacer ring 28 which allows flow of the returning fuel through itself.

Although the area where one pipe runs inside the other is relatively short in the illustration of Figure 2, in practice this configuration will be maintained over the whole length of the car, between the engine and the fuel tank.

The invention has the result that rupturing of the high pressure fuel line becomes very much less likely.

Furthermore it is only necessary to assemble a single pipe (the outer pipe 24a) to the vehicle body instead of two pipes.

Claims

1. A fuelling arrangement for an internal combustion engine, the arrangement comprising an engine, a fuel tank, a fuel feed line connecting the tank with the engine, and a fuel return line connecting the engine with the tank, wherein the fuel feed line is fitted inside the return line where the lines extend between the tank and the engine.

2. A fuelling arrangement as claimed in Claim 1, wherein the feed and return lines are formed in a single manufacturing process.

3. A fuelling arrangement as claimed in Claim 2, wherein two concentric tubes are formed by a single extrusion process.

4. A fuelling arrangement as claimed in Claim 1, wherein the feed line is threaded through a larger diameter pipe so that the return line is formed in the space within the larger diameter pipe which surrounds the feed line.

5. A fuelling arrangement as claimed in Claim 4, wherein separate spacer members are used to ensure concentricity of the feed line in the outer pipe.

6. A fuelling arrangement substantially as herein described with reference to Figures 2 to 5 of the accompanying drawing.