GB2038975A

GB2038975A - Fuel injection pump for internal combustion engines

Info

Publication number: GB2038975A
Application number: GB7943465A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1979-01-05
Filing date: 1979-12-18
Publication date: 1980-07-30
Also published as: IT7928255A0; JPS5593960A; DE7900195U1; IT1126622B

Abstract

The fuel injection pump is a "plug-in" type, whose fuel line connection renders possible a small overall height of the injection pump and facilitates the mounting and alignment of the fuel inlet and return lines. The pump includes a line connection piece (24) which is inserted into a smooth-wall connection bore (17) which leads through the wall of the pump housing (10) into the suction chamber (16). The line connection piece (24) is centered in the connection bore (17) by means of a longitudinally bored spigot (22) and is sealed by means of a sealing ring (26), and is held in its fitted position by means of a clamp (34) secured to the pump housing (10). The clamp (34) is placed over the end wall (24b) of the line connection piece (24) and is clamped against the fastening flange (18) of the injection pump by two fastening bolts. <IMAGE>

Description

SPECIFICATION Fuel injection pump for internal combustion engines The invention relates to a fuel injection pump of the type having a smooth-walled connection bore which serves to connect a fuel line and leads through the wall of the pump into the suction chamber.

Fuel injection pumps of this kind, used especially as plug-in pumps for fitting in the engine housing, are known from German Offenlegungsschrift 2,240,123 and have a fuel inlet lead which is screwed into a scrnwqhrnaded bore and, separate therefrom, a fuel return line inserted into the smooth-wall connection bore, the fuel return line being pressed or glued into the connection bore. In such fuel injection pumps of the PF and PFR types, which are also known from the publication VDT-UBP 001/14 Robert Bosch GmbH, Stuttgart, and which, in special variants, are also provided with a fastening flange located in the region of the suction chamber, fuel is usually fed by way of a commercially available pipe connection piece which is screwed into a screw-thread of the connection bore.A connection of this kind requires a correspondingly large wall thickness in order to absorb the forces occurring when tightening the pipe connection, and a corresponding amount of installation space for fitting and removing the pipe connection. The fuel return line in accordance with the above mentioned German Offenlegungsschrift is fitted in the smooth-wall connection bore and, owing to the fact that it is fixedly anchored in the pump housing, renders it difficult to fit and remove the pump and dismantle the line.

'There is provided by the present invention a fuel injection pump for internal combustion engines having a smooth-walled connection bore which serves to connect a fuel line and which leads through the wall of the pump housing into the suction chamber thereof, wherein a longitudinally bored spigot of a line connection piece, which contains a hollow space, is fitted into the connection borer and is sealed by means of a sealing ring, and the line connection piece is provided with the fuel line which is connected to the hollow space laterally of the longitudinal axis of the line connection piece, the line connection piece being held in its fitted position by a clamp secured to the pump housing.

In contrast to known pumps, the fuel injection pump in accordance with the invention has the advantage that the connection surface for mounting the fuel line can be located very near to the suction chamber of the pump, since the connection bore does not have to absorb any clamping forces. The retaining forces for the line connection piece are absorbed by the clamp and its fastening means, and the fuel line connected laterally to the hollow space of the line connection piece renders it possible to obtain an extremely flat construction of that portion of the line connection piece which extends beyond the pump housing, so that the fuel injection pump can be fitted without difficulty even in the case of very confined intallation conditions on the engine.

In a fuel injection pump constructed in accordance with the present invention and having a fastening flange arranged on the pump housing on a level with the suction chamber, and a connection bore disposed in the region between two fastening screws of the fastening flange, special fastening means for the clamp can be omitted if the clamp is placed over a closed end face of the line connection piece and is clamped to the fastening flange by the two fastening screws.

Satisfactory scavenging and venting of the suction chamber can be achieved in a simple manner by connecting a fuel inlet line and a fuel return line laterally to the hollow space of the line connection piece.

An embodiment is illustrated in the accompanying drawings, in which: Figure 1 is a longitudinal section through the components of the embodiment being a singlecylinder fuel injection pump; and Figure 2 is a view in the direction of the arrow II of Figure 1.

Referring to the drawings, a pump element comprising a pump cylinder 11 and a pump piston 12 guided therein is rigidly clamped by means of an externally threaded sleeve 14 in a housing 10 (only partially illustrated) of a fuel injection pump which is provided as a plug-in pump for fitting into a bore 9 in the engine housing M. This pump has a particularly small overall height and has a horizontal pipe connection for the pressure line (not illustrated) leading to the injection nozzle.

In the region of a control port 1 5 controlled by the pump piston 12, the pump cylinder 11 is surrounded by a suction chamber 16 which, in the present case, is the form of a hollow space in the pump housing 10. It will be appreciated that the suction chamber 16 can be in any other form and, for example, can be in the form of a portion of a connection bore 17. The connection bore 17 serves for the inflow and return flow of the fuel fed to the suction chamber 1 6.

The housing 10 carries, on a level with the suction chamber 16, a fastening flange 1 8 which is bolted to the engine housing M by means of two fastening bolts 19. The connection bore 17 commences, in the region between two fastening bolts 19 (see Figure 2), from a connection surface 21 located near to the suction chamber 18 and leads obliquely through the wall of the pump housing 10 into the suction chamber 16 and has a smooth cylindrical wall into which is fitted a longitudinally bored spigot 22 of the line connection piece 24 which incorporates a hollow space 23.The spigot 22 carries a sealingring 26, in the form of an O-ring, which is fitted in an annular groove, whereby axial clamping forces are not required to seal the connection bore 17, and, in this case, the connection surface 21 also does not require an accurately machined sealing surface. The hollow space 23 located in the head 24a of the line connection piece communicates with the suction chamber 16 by way of a bore 27 in the spigot 22 of the line connection 24, and with a fuel inlet line 31 and a fuel return line 32 by way of a respective one of two flexible tube connection nipples 28.Each flexible tube connection nipple 28 is secured in a respective transverse bore 33 which is bored through the wall of the head 24a at right angles to the longitudinal axis of the line connection piece 24 and, advantageously, the transverse bore 33 for the flexible tube connection nipple 28 carrying the fuel return line 32 is disposed such that it branches from the highest point of the hollow space 23 and thus renders possible satisfactory venting of the fuel injection pump.

A clamp bar 34 is placed over an end wall 24b of the line connection piece 24 which externally seals the hollow space 23, and presses the line connection piece 24 against the connection surface 21 on the pump housing 10 and is clamped against the fastening flange 1 8 by means of the fastening bolts 19.

The advantage of the low overall height can also be obtained when the clamp is secured to the pump housing by separate fastening bolts. In addition to the compact construction and the reliable sealing of the connection bore 1 7, the construction, of the embodiment, of the line connection piece 24 renders it a simple matter to dismantle this connection piece and to align the flexible tube connection nipple 28 in a simple manner into a position which is most favourable with respect to the installation conditions on the engine and which renders it possible to discharge the air, contained in the fuel, in a satisfactory manner.

Claims

1. A fuel injection pump for internal combustion engines having a smooth-walled connection bore which serves to connect a fuel line and which leads through the wall of the pump housing into the suction chamber thereof, wherein a longitudinally bored spigot of a line connection piece, which contains a hollow space, is fitted into the connection bore snd s sealed by means of a sealing riny, and the li;le connection piece is provided with tho fuel line which is connected to the hollow space laterally of the longitudinal axis of the line connection piece, the line connection piece being held in its fitted position by a clamp secured to the pump housing.

2. fuel injection pump as claimed in claim 1, wherein the fuel line is connected at right angles to the longitudinal axis of the line connection piece.

3. A fuel injection pump as claimed in claim 1 or 2, having a fastening flange which is disposed on the pump housing on a level with the suction chamber, and having the connection bore disposed in the region between two fastening bolts to the fastening flangs, wherein the clamp is placed over a closed end wall of the line connection piece and is clamped against the fastening by the two fastening bolts.

4. A fuel injection pump as claimed in claim 1, 2 or 3, wherein a fuel inlet line and a fuel return line are each connected laterally to the hollow space in the line connection piece.

5. A fuel injection pump as claimed in any of the claims 1 to 4, wherein a flexible tube connection nipple is secured in a transverse bore, connected to the hollow space, in the line connection piece for the purpose of connecting the fuel line.

6. A fuel injection pump substantially as hereinbefore described with reference to the accompanying drawings.