GB2325276A

GB2325276A - Mounting i.c. engine plug-in fuel injection pumps

Info

Publication number: GB2325276A
Application number: GB9810250A
Authority: GB
Inventors: Frank Berger
Original assignee: Daimler Benz AG
Current assignee: Daimler Benz AG
Priority date: 1997-05-15
Filing date: 1998-05-13
Publication date: 1998-11-18
Also published as: IT245639Y1; FR2763365A1; GB9810250D0; ITRM980130U1; DE29723055U1

Abstract

For each cylinder 3 of the i.c. engine a bore 4 is provided in the cylinder casing to receive a plug-in pump 5. The axis (a) of each plug-in pump 5 may be at an angle of about 10 degrees to the cylinder axis (b). Each pump 5 comprises an actuating part with a cam-driven spring-loaded roller tappet 10 which engages a camshaft 9, and a pumping part with a plunger 7. The actuating and pumping parts are combined in a single unit inside a sleeve 11. The longitudinal axis (a) of the pump 5 is spaced by a distance (x) from the camshaft axis (c) and intersects a perpendicular plane through the camshaft axis (c) at a point below the camshaft axis (c). This allows the inlet and exhaust valve tappet guides (18, fig.3), and hence the cylinders 3, to be closer together thus saving weight and space. Also the running of the roller tappets 10 is improved and installation and removal of the plug-in pumps 5 is simplified.

Description

1 Plug-in pump for an internal combustion engine 2325276 The invention

relates to a plug-in pump for an internal combustion engine, particularly but not exclusively a diesel engine.

EP 0,543,301 A 1 (particularly Figure 2) discloses a plug-in pump of this type, the pump part and actuating part of which are plugged in a receiving bore in the cylinder housing of an internal combustion engine. The pump part, having a pump plunger in the pump casing, is separated by design from the actuating part having a cam-driven roller tappet, but the pump part and actuating part are operatively connected,to one another. The longitudinal axis of the plug-in pump runs transversely relative to the camshaft axis and, in its imaginary extension, intersects the latter.

This camshaft also has cams which actuate gas exchange valves of the internal combustion engine via tappet push rods which are adjacent to the respective receiving bores of the plug-in pump of each cylinder.

The present invention seeks, by special positioning of the cam-driven plug-in pumps, to achieve an increase in constructional space for the cylinder housing along its longitudinal extent, whilst at the same time improving the running behaviour or alignment of the roller of the longitudinally displaceably guided roller tappet, and, simultaneously with this special positioning, also to achieve a simplification in the installation and removal of the plug-in pump, in order to minimize the repair outlay incurred by normal wear.

According to the present invention there is provided an internal combustion engine with receiving bores, provided in the cylinder housing, for plug-in pumps which consist in each case of a pump part with a pump plunger guided in the pump casing and of an actuating part with a camdriven and spring-loaded roller tappet, wherein the pump part and actuating part of the plug-in pump are combined as a structural unit by means of a sleeve surrounding the two parts and plugged in the receiving bore, the longitudinal axis (a) of the plug-in pump running, in its imaginary extension, at a distance from the axis (c) of the rollertappet/camshaft system acting as a tracking roller, so as to bring tappet guides of cylinder inlet and outlet valves closer together, in such a way that the extended longitudinal axis (a) of the plug-in pump intersects a plane running perpendicularly through the axis (c) of the camshaft, below 2 the camshaft axis. The subclaims also specify advantageous developments of the invention.

Assigning the plug-in pump to the camshaft in a special way ensures that the roller is aligned on the roller tappet and, acting as a tracking roller, brings about a substantially better or more stable running behaviour.

Furthermore, the positioning according to the invention of the plug-in pump, the longitudinal axis of which lies, in its imaginary extension, at a specific distance from the camshaft axis and intersects a perpendicular plane running through the axis of the camshaft, ensures a greater distance from the cylinder axis and brings the tappet guides of the inlet and outlet valves closer together, so that constructional space for the cylinder housing can be saved along the longitudinal extent of the latter, since the distances between the cylinders arranged in a row can be selected smaller. In addition to the saving of constructional space, a reduction in weight is obtained.

Although DE 40 40 937 Al discloses a cam/tappet system with a roller tappet for an injection pump, in which the roller axis is eccentric to the camshaft axis, nevertheless the extended longitudinal axis of the pump intersects a plane running perpendicularly through the axis of the camshaft, above the camshaft axis.

Due to the measures according to the invention, the pump part and actuating part may also, as a one-part element, be removed from the cylinder housing or plugged into the cylinder housing.

A further advantage is afforded in that the wearing components are located in the plug-in pump and not in the cylinder housing. Subsequent work in the cylinder housing when there are signs of wear is unnecessary. A separately testable unit is obtained.

DE 42 27 853 Al discloses a plug-in pump, in which a thin-walled sliding sleeve is arranged between the roller tappet of the cam drive, the said roller tappet being movable back and forth, and a bore in the housing of the internal combustion engine.

Claims

According to Claim 3, the roller tappet is reliably assigned in its

position to the cam of the camshaft. In addition to the roller tappet being secured in terms of rotation, at the same time it is secured against loss by means of a sliding block which slides in the sliding- block guide of the roller tappet and which is firmly connected to

3 the sleeve.

Although the plug-in pump according to DE 42 27 853 A I also has a device for fixing its rotary position, this is formed by a pin/slot connection.

An advantageous refinement of the invention is also obtained as a result of the special arrangement of the fuel run and the special design of the fuel connection in the critical region of two housing parts resting against one another.

The invention is illustrated in the drawing and is described in more detail below with reference to an embodiment. In the drawing:

Figure 1 shows a cylinder housing, illustrated in cross-section, of a multi-cylinder internal combustion engine having a plug-in pump, Figure 2 shows the cylinder housing with plug-in pump in an enlarged illustration, Figure 3 shows a top view of the cylinder housing of the internal combustion engine. Figures 1 and 3 show a cylinder housing I for a multicylinder internal combustion engine 2, with cylinders 3 arranged in a row and with vertical receiving bores 4, provided in the cylinder housing 1, for receiving plug- in pumps 5 controlled by solenoid valves. Each plug-in pump 5 assigned to a cylinder 3 is composed of a pump part with a pump plunger 7 guided in the pump casing 6 and of an actuating part with a spring-loaded roller tappet 10 co-operating with the pump plunger and driven by the cam 8 of a camshaft 9.

The pump part and actuating part are combined as a structural unit by means of an elongate sleeve 11 surrounding the two parts (Figure 2) and are plugged in the receiving bore 4 which is divided into bore portions 4a and 4b located at a distance from one another. The lower region of the pump casing 6 is plugged into the bore portion 4a which is at the top in the cylinder housing 1, whilst the sleeve 11 is plugged in the lower bore portion 4b. The roller tappet 10 is guided in the sleeve I I so as to be longitudinally displaceable counter to the force of a roller-tappet spring 12. A sliding block Ila fixed to the sleeve and a slot-like sliding-block guide 10a in the roller tappet 10 form a device for securing against loss, so that, when the plug-in pump 5 is removed from the receiving bore 4, the roller tappet spring 12 is prevented from falling out of the sleeve 11.

4 The lower region of the pump casing 6 is of stepped design, and the part 6a of larger diameter has two sealing rings 30, 40 located one above the other and is mounted in the upper bore portion 4a, whilst the part 6b of smaller diameter is firmly connected to the upper part of the sleeve 11. In this case, a thrust shoulder 15 on the pump casing 6, the said thrust shoulder being formed by the step, rests on the end face 15 of the sleeve 6 (Figure 2).

The exposed pump-casing part 6 projecting from the receiving bore 4 contains a solenoid valve 16 for controlling the flow paths in the fuel lines.

The plug-in pump 5, is placed in such a way that its longitudinal axis a and the cylinder axis b form an angle ct of about 10".

The longitudinal axis a runs transversely relative to the axis c of the camshaft 9, whilst the imaginary extension of the longitudinal axis a is at a distance x from the camshaft axis c, in such a way that the extended longitudinal axis a of the plug-in pump 5 lies behind the camshaft axis c, as seen from the cylinder 3 in the direction of the camshaft 9. The direction of rotation of the camshaft 9 is anti-clockwise, which means that the roller 17 of the roller tappet 10 acts as a tracking roller and thus acquires stable alignment in terms of its mounting and running.

Due to the special placing or assignment of the plug-in pump 5 relative to the camshaft 9, tappet guides 18, 19 of each cylinder 3 can be brought closer together and, consequently, the adjacent cylinders 3 can be nearer to one another (Figure 3). The benefits are a weight saving and a reduction in constructional space.

The exposed pump-casing part projecting from the receiving bore 4 is provided with a lateral casing projection 20. This part of the pump casing and the housing projection 20 rest on a bearing surface 21 of the cylinder housing 1, the said bearing surface running at right angles to the longitudinal axis a of the plug-in pump 5.

According to Figures 1 and 2, the lateral housing projection 20 has a fuel line 22 with a stepped line portion 23 which runs parallel to the longitudinal axis a of the plug-in pump 5 and which is arranged coaxially relative to a supply duct 24 in the cylinder housing 1. The supply duct 24 branches off from a longitudinal duct 25 which extends as a continuous outgoing fuel feed in the cylinder housing 1 next to the plug-in pumps 5.

A fuel sleeve 26 is pushed into the line portion 23 as far as a thrust shoulder 27 formed by the step and is fixed there. The fuel sleeve 26 is plugged, with its part projecting from the line portion 22, in the supply duct 24 of the cylinder housing I and forms a device for securing the plug-in pump 5 in position in the receiving bore 4. The plug-in pump 5 is fastened to the cylinder housing 1 by means of fastening screws 28.

The bearing surface 29 on the housing projection 20, the said bearing surface being opposite the bearing surface 21 on the cylinder housing 1, is provided with a recess 30 which surrounds the sleeve 26 and in which is located a sealing ring 31 which is pushed under prestress onto the sleeve 26 so as to be secured against loss. The fuel sleeve 26 making the line connection between the cylinder housing 1 and the plug-in pump in this special way protects the sealing ring 31 against the very high system pressure which prevails.

6 Claims An internal combustion engine with receiving bores, provided in the cylinder housing, for plug-in pumps which consist in each case of a pump part with a pump plunger guided in the pump casing and of an actuating part with a cam-driven and spring-loaded roller tappet, wherein the pump part and actuating part of the plug-in pump are combined as a structural unit by means of a sleeve surrounding the two parts and plugged in the receiving bore, the longitudinal axis (a) of the plug-in pump running, in its imaginary extension, at a distance from the axis (c) of the roller- tappet/camshaft system acting as a tracking roller, so as to bring tappet guides of cylinder inlet and outlet valves closer together, in such a way that the extended longitudinal axis (a) of the plug-in pump intersects a plane running perpendicularly through the axis (c) of the camshaft, below the camshaft axis.

2. An internal combustion engine according to Claim 1, wherein the distance between the extended longitudinal axis (a) of the plug-in pump and the camshaft axis corresponds to about one seventh of the diameter of the roller tappet.

An internal combustion engine according to Claim 1 or 2, wherein the roller tappet contains a slot-like sliding-block guide which, with a sliding block of the sleeve, forms a device for securing against loss.

4. An internal combustion engine according to Claim 1, wherein the lower region of the pump casing is firmly connected to the upper part of the sleeve, on the end face of which rests a thrust shoulder of the stepped pump easing.

5. An internal combustion engine according to Claim 1, wherein, in a fuel line which adjoins a supply duct for fuel which is located in the cylinder housing at a level with the plug-in pump and which runs in a lateral housing projection of an exposed pump-casing part of the plug-in pump, the said part projecting from the receiving bore, a fuel sleeve is inserted, on the one hand, partly in the supply duct of 7 the cylinder housing and, on the other hand, partly in the fuel line of the pump-casing part.

6. An internal combustion engine according to Claim 5, wherein the fuel line has a line portion which is arranged coaxially relative to the supply duct in the cylinder housing and is of stepped design and the step of which is provided as a stop for the fuel sleeve.

7. An internal combustion engine according to Claims 5 and 6, wherein the line portion in the lateral housing projection has a recess for receiving a sealing ring which surrounds the fuel sleeve under prestress and which secures against loss.

8. An internal combustion engine according to Claim 4, wherein the bearing surface for the exposed pump-casing part together with its lateral housing projection runs transversely relative to the longitudinal axis (a) of the plug-in pump, and each cylinder axis (b) and its associated longitudinal axis (a) of the plug-in pump form an angle of about ten degrees.

9. An internal combustion engine substantially as described herein with reference to and as illustrated in the accompanying drawings.