VALVE GEAR LUBRICATION FOR AN INTERNAL COMBUSTION ENGINE

Abstract: For an internal combustion engine having oil-spray lubrication of an overhead camshaft an assembly is provided which comprises a central filter case (21) which can connect by a nipple (31) with an existing oil supply conduit (15) in an engine to receive oil therefrom and on a downstream side of a filter screen (23) connects with pipes (20a, 20b) which have apertures whence oil sprays (36) can issue.

Description: INTERNAL CONBTJS TI ON ENGINE mhis invention relates to an internal combustion engine having an overhead camshaft to parts of which lubrication is applied by spraying. Lubrication of the interface between each cam of an overhead camshaft and the component against which the cam operates e.g. valve stem, tappet, rocker, ultimately controlling the aspiration valves of an internal combustion engine, is often effected by spraying. The Drimaryobjective of such lubrication is to direct a spray of oil on to an intended area of the cam and/or the component against which the cam directly operates. Effective lubrication of the said interface is mainly dependent on maintaining a sufficient oil spray onto the intended area. The spray is usually emitted from a small hole or jet in a conduit situated conveniently near the said area and fed from the engine oil pump by pipes and/or oilways in thecylinder block and head. An avers engine oil filter is effective in preventing the flow, in the general oil circuits, of particles which would be injurious to sleeve and rolling bearings. However, it does allow to pass minute particles which in time, become coagulated on the walls of pipes or oilways to form areas of "crust". Any nieces of this "crust" subsequently dislodged are able to circulate the oilways or pipes and may reach lubrication areas without being influenced by the filter. Eile such pieces are usually too soft by their nature to inSure sleeve or rolling bearings, they have enough size and tenacity to block the spray holes of the spray lubrication system, thereby starving the cams of their lubrication. The said pieces may become dislodged purely by the flow of oil in the pipes or oilways, but their incidence is enhanced by the addition of or change to a higher detergent oil than normally used. This is particularly noticeable after the engine has been "flushed out". tn object of the present invention is to provide an O.H.C. internal combustion engine wherein this problem is obviated or r.inimised. accordingly the invention provides an internal combustion engine having an overhead camshaft and an oil supply to anertures for spray lubrication of the camshaft, filter means being provided in said oil flow to prevent or discourage solid material from reaching the spray apertures. Because the chance of such a blockage increases with the length of conduit such as piping and/or oilways leading to the spray holes the filter should be positioned as far downstream in the oil stream flow as conditions allow; preferably in the final stage, just before the spray holes, in order to minimise the likelihood of blockage. The invention will be described further, by way of example, with reference to the accompanying drawings wherein: Fie. 1 is 2 terspective view of an engine modified in accordance with the present invention; fits. 2 and 2a are fragmentary views, respectively a nerspective view of a spray conduit and a tart-sectional view showing the conduit connected to a cylinder head in a conventional internal combustion engine; Fig. 3 is a view similiar to that of Fig. 2 but showing the conduit modified and connected to a filter illustrated in exploded form; ; an.d wig. 4 is a view similar to that of Fig. 2(a) but showing the filter in position connecting the conduit to the cylinder.block of an engine. The chosen example of engine of the invention is the R > itish Ford Petrol engine 1600 OHC or 2000 OHC currently in Droduction. In this style of engine, camshaft lubrication oil ascends from the engine oil pums and filter, both situated low down near the sump, through an oilway in the cylinder block, through a perforation in the cylinder head gasket, through an oilway in the cylinder head into the camshaft centre bearing pedestal from which it passes through a horizontally drilled oilway into the spray pipe assembly (Fig. 2). Pig. 2 is a pictorial view of an assembly consisting of a spray pipe 10, nipple 11 and bracket 12. The assembly is that Ford Part which in U.K. is given No. 1490126 and which in Europe and U.S.A. is marked 70 HM 6578AE and DIFZ-6574.respectively. The assembly is secured by a bolt 13 to the side of the camshaft centre bearingspedestal 14 (Fig. 2a) while the nipple 11 enters a horizontally drilled oilway 15, to receive and transmit oil to the pipe 10. From this noint oil flows into the fore and aft halves of the nitre lna lOb finally to emerge as a spray 16 from each of eight stray holes 17, one spray lubricating each of eight cams (not illustrated). The ends } > of the pipe are sealed, and secured by one bolt each (not shown) to the camshaft fore and aft bearing pedestals (also not shown). It is this existing system which is vulnerable to blocking of the spray holes 17. Another hazardous feature of this particular engine lies ir the fact that the oil passes from an oilway in the cylinder block to an oilway in the cylinder head via the cylinder head gasket. Therefore, very special care must be taken, when changing the cylinder head gasket for maintenance purposes, that foreign matter, such as scranings does not enter the oilway in either the cylinder bloc or the cylinder head, for on re-starting the engine, such matter could be carried along by the oil and block one or more of the spray holes. Referring simultaneously to Figs. 3 and 4, in an engine in accordance with the invention the innermost ends of pine halves 20a, 20b are removed by cutting and the two ends resulting are secured by brazing into two holes, one in each side of a filter case 21 in such a manner that the said ends do not protrude into the inside of the case 21 but the bores of the pipes 20a, 20b connect with the inside of the case. 21. When the case 21 is being made, holes for the ends of pipes 2na, 20b are punched out to form a short tubular spigot 32 which facilitates brazing of the pipe ends to the case 21 and increases the tolerance in the length to which the pipe halves 20a, 20b have to be cut. Filter components are assembled in the case (1) in the follow no order: z O PinFP 29 screen 23 Plate Spacer 25 Plate 'O' Ping 27 Lid yoke This assemblv is then secured to the camshaft centre bearing pedestal by 2 bolt 30 which may be tightened solidly and yet apply a dimensionally controlled connression to the two 'O' ring seals 22, 27 because of the limit to its movement imposed by the solid centre parts of the various components forming a stack around it. At the same time a nipple 31 on the case 21 enters the horizontally drilled hole 15 (Fig. 4) in the camshaft centre bearing pedestal 33 to admit oil to the filter case 21. The ends of the tipes 20a, 20b are secured as before to the camshaft fore and aft bearing pedestals (not shown). aSow referring to Fig. 3. On starting the engine, oil passes from the drilled hole 15 in the camshaft centre bearing pedestal 33 through the nipple 31 into chamber 34 from where any subsequent flow must be through filter screens 23 the whole area of which is available to pass oil but to stop particles greater than a given size and to collect such particles in chamber 311. The now filtered oil flows through holes 35 in plate 24 into annulus 36 into the bores of pipe 20 and is finally emitted from the spray holes onto the intended area of the cam.

Claims: CLAIM.S: l. P.n internal combustion engine having an overhead camshaft and an oil supply to apertures for spray lubrication of the cam surfaces characterised in that filter means is provided in the oil flow to the apertures to discourage solid particles from reaching and blocking the apertures. 2. An engine as claimed in Claim 1, characterised in that the filter means comnunicates immedi2tely with oil supDly pines in which the spray apertures are provided. 3. tn engine as claimed in Claim 2, characterised in that two tines connect with the filter means on a downstream side of a screen thereof and a chamber on an upstream side of the screen has a nipple communicating therewith and dimensioned to engage an oil supply cavity in structure of the engine. 4. an engine as claimed in claim 3, characterised in that the filter means comprises a case and, within the case, comnonents for defining a chamber one o each side of the screen and sealing with the screen to enforce flow through the screen. An at engine as claimed in claim 4, characterised in that said components are secured in the case and the case is secured to the engine by a single fastener passing through the centre of all the components which are shaped to define a stack around the bolt. An at benzine as claimed in claim 1 and substantially as hereinbefore described with reference to the accompanying drawings. 7. A camshaft lubricating oil supply assembly comprising a filter having an inlet adapted to connect with an oil supply conduit of an engine and an outlet to a conduit supplying. oil to spray apertures for cam lubrication. An An assembly as claimed in claim 7 characterised in that the filter has a case which is central and supplies tiltereg oil to two pipes each of which has spray apertures therein. an assembly as claimed in claim 8, characterised in that components of the filter can be secured in the case and the case can be secured to an engine by 2 single central bolt. 10. 9 camshaft lubricating oil supply assembly, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

Inventors: HOLDING, NORMAN
Applicants: HOLDING, NORMAN
Application year: 1981
Main classification: F01M9
IPC codes: F01M9, F01M11