TITLE

HIGH-PRESSURE PUMP AND FUEL FEED SYSTEM COMPRISING SAID

HIGH-PRESSURE PUMP

The present invention relates to a high-pressure pump and a fuel feed system for an internal-combustion engine comprising said high-pressure pump.

The fuel feed systems of the known type generally comprise a high-pressure pump, a low-pressure pump designed to supply the fuel to the high-pressure pump via a feed line, and a common rail fed with high-pressure fuel by the high- pressure pump via a high-pressure delivery line.

The high-pressure pump comprises a pump body provided with at least one pumping member and a high-pressure delivery duct designed to be connected to the high-pressure delivery line. The connection between the high-pressure delivery line and the high-pressure delivery duct is normally performed by means of a connecting part which is screwed into the pump body opposite the high- pressure delivery duct.

The connecting part therefore constitutes an additional component to be assembled during installation of the high-pressure pump, with obvious disadvantages from the point of view of the time and costs of the assembly operations.

It is an object of the present invention to provide a fuel feed system and a high- pressure pump which are devoid of the drawbacks of the prior art mentioned hitherto; in particular it is an object of the invention to provide a high-pressure pump which can be assembled easily and rapidly.

In accordance with these objects, the present invention relates to a high-pressure

pump for feeding fuel to an internal-combustion engine, comprising:

a pump body comprising a high-pressure delivery duct which is designed to be connected to a high-pressure delivery line, and a connecting part for connecting the high-pressure delivery duct to the high-pressure delivery line, the pump being characterized in that the connecting part is incorporated in the pump body.

The present invention also relates to a fuel feed system for an internal- combustion engine, comprising:

a common rail, a high-pressure delivery line for feeding high-pressure fuel to the common rail, a high-pressure pump comprising a pump body, and a high- pressure delivery duct formed in the pump body and designed to be connected to the high-pressure delivery line, the system being characterized in that the high- pressure pump is of the type claimed in any one of Claims 1 to 6.

Further characteristic features and advantages of the present invention will emerge clearly from the description which follows of a non-limiting example of embodiment thereof, with reference to the figures of the accompanying drawings in which:

- Figure 1 is a schematic diagram of a detail of a fuel feed circuit according to the present invention; and

- Figure 2 is a cross-sectional view of a detail of the high-pressure pump according to the present invention.

In Figure 1 the reference number 1 denotes a fuel feed circuit for an internal- combustion engine (not shown). The circuit 1 comprises a high-pressure pump 2, a low-pressure feed line 3, which connects a low-pressure pump (not shown for the sake of simplicity in the accompanying figures) to the high-pressure pump 2, and a high-pressure delivery line 4 which connects the high-pressure pump 2 to a common rail (not shown in the accompanying figures).

The high-pressure pump 2 comprises a pump body 5 (indicated in Figure 1 by a dot-dash line) which houses three pumping members 7, a feed circuit 8 and a delivery circuit 9.

The feed circuit 8 comprises a low-pressure feed duct 10 which is connected to the feed line 3 and divides into three auxiliary feed ducts 11, each of which feeds a respective pumping member 7.

The delivery circuit 9 comprises a delivery duct 12 and three auxiliary delivery ducts 13 inside which the high-pressure fuel from the respective pumping members 7 flows. The auxiliary delivery ducts 13 converge into the delivery duct 12 which is connected to the high-pressure delivery line 4, as we shall see in detail further below.

Each pumping member 7 is defined by a respective cylinder 15 along which a respective piston 16 slides with a reciprocating movement. Each cylinder 15 is connected to the respective auxiliary feed duct 11 via a feed valve 17 and is connected to the respective auxiliary delivery duct 13 via a delivery valve 18.

The three pumping members are arranged radially at 120° with respect to a shaft

19 which forms part of a mechanism 20 for actuating the three pistons 16. The actuating mechanism 20 comprises essentially a cam 21 for actuating the three pistons 16, which is fixed onto the shaft 19 rotating in a known manner on supports mounted on the pump body 5. The cam 21 is designed to actuate a prismatic ring 22 which has three flat faces 23, each of which rests on a respective piston 16 of the pumping member 7.

The pump body 5 comprises, moreover, a connection assembly 24 (indicated schematically in Figure 1 by means of a rectangle) for connecting the high- pressure delivery duct 12 to the high-pressure delivery line 4.

With reference to Figure 2, the delivery line or pipe 4 is substantially cylindrical and has an end 25 designed to be connected to the delivery duct 12. In particular, the delivery pipe 4 is provided, close to the end 25, with an annular

- A -

edge 26 which projects radially relative to the delivery pipe 4. The end 25 of the delivery pipe 4 has a substantially frustoconical form which widens towards the annular edge 26.

The connection assembly 24 comprises a connecting part 28 and a ring nut 29.

The connecting part 28 is formed as one piece with the pump body 5 and extends from an outer face 30 of the pump body 5.

In particular, the connecting part 28 is a hollow cylindrical body provided with a threaded external cylindrical face 31 and an internal opening 32 which defines part of the delivery duct 12. This internal opening 32 comprises a first portion 33, which defines a seat 33 for receiving the end 25 of the delivery pipe 4 and a second portion 34 which is connected continuously to the first portion 33.

The first portion 33 of the internal opening 32 has a substantially frustoconical form which widens towards the outside of the pump body 5 so as to be able to receive the end 25 of the delivery pipe 4.

The ring nut 29 is threaded internally and is provided with a central hole 36 for receiving the delivery pipe 4.

The ring nut 29 is designed to be screwed onto the connecting part 28 and to grip the annular edge 26 between the ring nut 29 and the connecting part 28.

The high-pressure pump 2 provided in accordance with the present invention is particularly simple and fast to assemble since the connecting part 28, being formed as one piece with the pump body 5, does not have to be screwed onto the pump body 5. Moreover, the elimination of one component simplifies considerably the management of the manufacturing plant warehouses.