GB2268543A

GB2268543A - Mounting a fuel injection pump and nozzle unit on an i.c.engine cylinder head.

Info

Publication number: GB2268543A
Application number: GB9312233A
Authority: GB
Inventors: Erwin Ditschun
Original assignee: Volkswagen AG
Current assignee: Volkswagen AG
Priority date: 1992-07-10
Filing date: 1993-06-14
Publication date: 1994-01-12
Anticipated expiration: 2013-06-14
Also published as: GB9312233D0; GB2268543B

Abstract

Integral arms 13 on the unit 11 receive the rocker shaft 9 which is bolted to bearing blocks 2 of the camshaft 5 such that the unit is secured to the cylinder head 1. The camshaft 5 operates four valves per cylinder arranged around the nozzle 11b. One of the valves (44, Figs. 4 and 5) may be located beneath the rocker arm (57) operating the unit 11. <IMAGE>

Description

2268543

DESCRIPTION "CYLINDER HEAD, HAVING A PUMPING NOZZLE UNIT, FOR AN INTERNAL COMBUSTION ENGINW

The invention relates to a cylinder head for an internal combustion engine of the kind having gaschanging valves and a pumping nozzle unit for the injection of fuel which includes a high-pressure pump part. an integrated rocker arm spindle bearing and a fuel injection nozzle part.

A cylinder head of this kind, equipped with a pumping nozzle unit. is known from DE-OS 41 22 284, is constructed in such a way that the pumping nozzle unit which, by way of two arms which enclose a rocker arm therebetween, supports the associated rocker arm spindle, is mounted on a support surface of the actual cylinder head by means of a fastening flange provided on the pumping nozzle unit. Bearing supports bolted onto a further support surface. extending at an angle to the first-mentioned support surface, of the actual cylinder head serve to mount the camshaft associated with the rocker arm. A fastening flange of this kind, as is also used in the construction in accordance with DE-OS 39 28 104. may involve spatial difficulties. particularly when the cylinder head is provided with a larger number of gas-changing valves such as two intake valves and two exhaust valves per combustion -2chamber. The two above-mentioned support surfaces on the actual cylinder head which do not extend in one plane also require a relatively high expenditure on manufacture, since they have to be produced accurately to size and, owing to the angle between them, their manufacture requires two clamping operations.

The prior art - US-PS 4 522 182, and 4 602 604, also includes constructions in which one and the same camshaft carries cams for the actuation of the pumping nozzle unit and of the gas-changing valves. The construction in accordance with the secondmentioned of the latter specification has a bearing support through which the rocker arm spindle passes and which also forms a half-shell-shaped bearing for the camshaft. However, in contrast to the cylinder head in accordance with the generic type, these two pumping nozzle units do not have a bearing for the rocker arm spindle.

An object of the present invention is to provide a cylinder head. of the type mentioned hereinbefore, having a pumping nozzle unit and in which the pumping nozzle unit requires only a small installation space and can also be accommodated in the case of two intake valves and two exhaust valves per combustion chamber and small spaces between the combustion chambers and is inexpensive to manufacture.

In accordance with the invention, this is achieved in that the rocker arm spindle is secured outside the bearing in bearing blocks which are disposed laterally at right angles to the rocker arm spindle on a support surface of the cylinder head and which at the same time form fastening means for the pumping nozzle unit.

Thus, in the invention, the pumping nozzle unit is secured to the cylinder head by way of the rocker arm spindle and the bearing blocks for the latter. so that the fastening flange provided in the prior art discussed initially is omitted and thus the unit itself projects laterally to only a small extent. The modular type of construction is fully retained. The invention renders it possible to mount the unit even in the case of cylinder heads having two intake valves and two exhaust valves, especially since the bearing blocks may be secured on the edge of the cylinder head outside the space required for the valves. The lever arms of the acting forces are also effectively reduced by the invention in that the forces are diverted by way of the bearing blocks and no longer enter the pumping nozzle unit. Furthermore, the distances between the cylinders may be reduced.

By virtue of the parallelism of the camshaft and the securing of the pumping nozzle unit by way of the rocker arm spindle and the bearing blocks for the latter. the surfaces requiring accurate manufacture may be moved into one plane and may be machined in one operation. Since at least a partial mounting of the rocker arm spindle and of the camshaft lies in the bearing blocks and thus in the cylinder head, the relative distances apart can be readily fixed and can no longer change..

When a displacement piston is provided in the pumping nozzle unit for the pre-injection of fuel, it is advantageous to offset the corresponding reception bore laterally relative to the high-pressure pump part and the injection nozzle part and not between the two parts. This measure gives the pumping nozzle unit an even slimmer shape and its over-all height is reduced.

The invention is described further hereinafter, by way of example only. with reference to the accompanying drawings, in which:- Fig. 1 is a diagrammatic side elevation of one embodiment of a cylinder head in accordance with the present invention; Fig. 2 is a plan view of the embodiment of Fig. 1, showing a pumping nozzle unit, but without the intake and exhaust valves disposed on the cylinder head; Fig. 3 is a section on the line III-III in Fig. 2; Fig. 4 is a cross sectional view through a second embodiment of cylinder head in accordance with the present invention; and Fig. 5 is a plan view of the second embodiment.

A cylinder head 1, on which a bearing block 2 is secured, is indicated in Figure 1. The bottom support surface 3 of the bearing block 2 is planar in a manner advantageous for manufacture and has a semi-circular recess 4 which, together with an identical recess in the cylinder head 1, forms a bearing for the camshaft 5. A roller 8 mounted in a rocker arm 7 abuts against a cam 6 secured to the camshaft 5. The rocker arm 7 is pivotably mounted on a rocker arm spindle 9 and its free end 7a acts upon an actuating member 10 for a high-pressure injection pump lla which is only shown in elevation.

The pumping nozzle unit 11 extending into the cylinder head 1 is located below the free end 7a and comprises the high-pressure pump part lla and a fuel injection nozzle part llb. The two parts lla and 1 lb are disposed directly one behind the other, and the oblique bore 12 for a displacement piston may be seen laterally adjacent to their region of transition. Two -6projecting arms 13 are mounted laterally on the top end of the pumping nozzle unit 11 and their free ends embrace the rocker arm spindle 9 and are rigidly connected thereto. The longitudinal axis x of the highpressure pump part 11a extends parallel to the longitudinal axis y of the fuel injection nozzle part llb, although it is laterally offset by the distance A.

Figure 2 again shows the camshaft 5 having the cam 6 against which the roller 8 mounted on the rocker arm 7 abuts. The pumping nozzle unit 11 and the transversely extending bore 12, in which the displacement piston 14 is indicated, are also shown. The bearing blocks 2 are disposed laterally on the cylinder head and, in the example, are rigidly connected thereto by three bolts 15. The rocker arm spindles 9 of two cylinders located adjacent to one another are secured to the bearing blocks 2 by a bolt 16. The individual cylinders may thereby be positioned nearer to one another and the entire length of the engine may be shortened. There is adequate free space between the cam 6 and the bearing blocks 2 for accommodating two intake passages and two exhaust passages which lead to intake valves and exhaust valves characterised only by their centre point 17.

The securing of the rocker arm spindle 9 in the bearing block 2 may be clearly seen in Figure 3. A circular-segment-shaped recess 18, in which the rocker arm spindle 9 is mounted, is provided in the bearing block 2. A flat 19 and a bore 20 are provided at the ends of each rocker arm spindle 9. The bolt 16, whose head 21 abuts against the flat 19, is guided through the bore 20 and is screwed into the bearing block 2. Finally. the bolts connecting the bearing block 2 to the cylinder head 1 may also be seen in side view. The bearing blocks 2 form the means of securing the pumping nozzle unit 11 by way of the rocker arm spindle 9, so that a fastening flange occupying a large amount of space is not required for the pumping nozzle unit 11.

In the embodiment of Figures 4 and 5, it is assumed that four gaschanging valves 41, 42, 43 and 44 are provided for each combustion chamber in the actual cylinder head 40 and form a cross-like arrangement in plan view (Figure 5) and are actuated by way of further rocker arms 45, 46, 47 and 48 by cams 49, 50, 51 and 52 which are mounted on the camshaft 53 which also carries the cam 54 for the actuation of the pumping nozzle unit 55. As is shown in Figure 5 for the rocker arm 47, at least individual -8ones of the rocker arms may have regions which are curved in such a way that they embrace the pumping nozzle unit 55. The valves and the pumping nozzle unit extend parallel to one another and to the longitudinal axis of the associated cylinder.

As in the first embodiment, a rocker arm 57 is disposed between the injection cam 54 on the one hand and the actuating member 56 of the pumping nozzle unit 55 on the other hand andr by means of the roller 58. rests on the associated cam 54 in a low-friction manner and, in the manner already described, is mounted on the pumping nozzle unit 55 by way of arms 59 and is also secured by means of bolts 60 to laterally disposed bearing blocks 61 and 62 which are in turn clamped by a planar support surface 65 to the actual cylinder head 40 by means of bolts 63 or cylinder head bolts 64.

As is indicated at 66 in Figure 4, pressure medium may be supplied by hydraulic valve clearance. compensators 67 by way of oil bores in the rocker arm spindles and in the rocker arms which are associated with the individual valves.

As will be seen from the plan view of Figure 5, one of the valves, namely the valve 44, is located below the rocker arm 57 associated with the pumping nozzle unit 55. In accordance with Figure 4, the -9arrangement of its rocker arm 48 is chosen in such a way that its rocker axis is located below the camshaft 53 or at the end of the camshaft 53 remote from the injection rocker arm 59. In conjunction with the chosen arrangement of the gas-changing valves 41, 42, 43 and 44. that is. approximately in the form of a cross turned slightly towards the longitudinal axis of the machine or the axis of the camshaft, a particularly compact arrangement results without having to accept troublesome limitations with respect to the construction and arrangement of individual components.

======== ----------------

Claims

1. A cylinder head for an internal combustion engine, having gas-changing valves and a pumping nozzle unit for the injection of fuel which includes a high-pressure pump part. an integrated rocker arm spindle bearing and a fuel injection nozzle partr the rocker arm spindle being secured outside the rocker arm spindle bearing in bearing blocks which are disposed laterally at right angles to the rocker arm spindle on a support surface of the cylinder head and which at the same time form fastening means for the pumping nozzle unit.

2. A cylinder head as claimed in claim 1, wherein the side of each bearing block remote from the cylinder head has a circular-segment-shaped to semicircular partial bearing for receiving the rocker arm spindle.

3. A cylinder head as claimed in claim 2, wherein the rocker arm spindle has in the region of the bearing blocks a flat and a bore extending at right angles thereto for receiving a bolt whose head abuts against the flat after the bolt has been screwed into the bearing block.

4. A cylinder head as claimed in any of claims 1 to 3, wherein the support surface of each bearing block facing the cylinder head has a semi-circular recess for a bearing of a camshaft associated with the pumping nozzle unit.

5. A cylinder head as claimed in any of claims 1 to 4. wherein the bearing blocks are secured to the cylinder head by means of bolts.

6. A cylinder head as claimed in any of claims 1 to 5, wherein the.highpressure pump part and the injection nozzle part are disposed directly one behind the other and their longitudinal axes extend parallel to one another.

7. A cylinder head as claimed in any of claims 1 to 5, wherein the highpressure pump part and the fuel injection nozzle part are disposed directly one behind the other on a comon longitudinal axis.

8. A cylinder head as claimed in claim 6 or 7, having a pumping nozzle unit which additimally has a bare for receiving a displacement piston for the pre- injection of fuel. the latter bore being offset laerally ttlatic& h thg highoprogsur@ pap part and to the fuel injection nozzle part and extending transversely to the longitudinal axes thereof,

9. A cylinder head as claimed in claim 41 or claim 4 and any of claims 5 to 8. wherein the camshaft carries, in addition to a cam for the actuation of the pumping nozzle unit, further cams for the actuation of the gas-changing valves by way of further rocker arms or valve rockers.

10. A cylinder head as claimed in claim 9, wherein four gas-changing valves per combustion chamber are provided around the pumping nozzle unit in a cross-like arrangement in plan view, and at least one of the further rocker arms or valve rockers extends below the rocker arm associated with the pumping nozzle unit and is mounted below the camshaft.

11. A cylinder head as claimed in claim 10, wherein at least one of the further rocker arms or valve rockers embraces the pumping nozzle unit with a region which is curved in plan view.

12. A cylinder head as claimed in any of cl ims 9 to 11, wherein the gaschanging valves and the pumping nozzle unit extend parallel to one another.

13. A cylinder head as claimed in claim 12, wherein the gas-changing valves and the pumping nozzle unit extend parallel to the longitudinal axis of an associated cylinder.

14. A cylinder head for an internal combustion engine, substantially as hereinbefore described, with reference to and as illustrated in the accompanying drawings.