Title of Invention

A CYLINDER HEAD

Abstract

A cylinder head for an overhead cam operated internal combustion engine, comprising a lower part and an upper part; the lower part accommodating components including the cam shaft, rocker arms, cam driven sprocket, valve assemblies; and spark button(s); the upper part seating itself on a ledge, provided all around the external periphery of the lower part, to provide a cover for the lower part, said ledge being located at a predetermined level below the top surface of the camshaft hearing housing' a recess provided on the side wall of the lower part, in alignment with the cam bore of the lower part, the mouth of the recess being flush with the ledge and of size facilitating assembly of the camshaft and machining of the cam bore, said recess receiving a stopper in snug fit, so as to provide a cover for the recess, while a button on the stopper is closely disposed to the end face of the cam driven sprocket and thus results in arresting any axial movement of the camshaft away from the bearing housing, the stopper being firmly held in place within the recess whenever the upper part is placed on the lower part and fastened thereto.

Full Text

This invention relates to a cylinder head applicable for overhead cam operated 4-stroke single cylinder internal combustion engines. In any known type of overhead cam operated cylinder head of a single cylinder I.e. engine the cylinder head is made with one single piece, in which the integrated cams (i.e., for inlet and exhaust) with camshaft are rotatably mounted through ball bearings. Also the rocker arms respectively for inlet and exhaust are pivotally connected to the cylinder head in • the known way. There is an opening with a cover fastened therewith so as to access the driven sprocket for assembly, setting or dismantling with the camshaft inside the cylinder head. There are two more openings with respective similar covers so as to provide access for tappet adjustment of the valve stem. This known art has the following demerits: Highly complicated shape of cylinder head results in difficulties for making the mould/die design, heavy weight and poor cooling fin-provisions and longer lead time and cost for casting; subsequently machining difficulties result in longer lead time and cost for machining and the highly congested space for servicing / assembly / dismantling of cam-train and tappet adjustments. In another version of the known art, the cylinder head is horizontally split in two halves, of which one is at the top and the other is at the bottom. This split surface is at the axis of over-head camshaft so that the assembly and dismantling of camshaft is possible by assembly and dismantling of these vertical two halves of cylinder head. Fasteners are commonly,, employed for integrally assembling these two-halves together and the cylinder head with cylinder block * This version of the known art has the following drawbacks: The difficulty in machining the camshaft bearing housing-bore, which is the result of the camshaft bearing housing being at both top and bottom halves; the space constraint for servicing / assembly / dismantling of the assembly of cam-train and tappet adjustments and the longer time required for assembly or servicing of valve-train or adjustment of the timing of cam-train and tappet clearances. In yet another version of the known art, the camshaft bearing housing of the aforesaid lower half of cylinder head further consists of two halves, which are fastened together. These two (upper and lower) halves of bearing housing part are machined with half cylindrical surface, which makes it very difficult for achieving alignment of the bearing axis on these halves. Thus this version of the known art has the following drawbacks: the possibilities of geometrical mis¬alignment on both these two halves of the camshaft bearing housing-bore and consequently poor functional performance of valve-train which results from possibilities of mis-alignment. According to this invention, the cylinder head consists of two parts: the first is the lower part, which consists of integrated camshaft, rocker arms, driven sprocket, valve- assemblies and spark ~" t"{ug(s); the second is the upper part, which covers the assembly of all parts inside the cylinder head. The said lower part of cylinder head is provided with a semi-circular recess of sufficient size so that the said integrated camshaft can be easily assembled with said lower part and also the bore for camshaft bearing housing can be made by any known ‘simple machining process, which is easier, cost effective and reliable for achieving geometric accuracies. The mating surface of assembly of horizontally two halves of said cylinder head is substantially below the top surface of cam shaft bearing housing of cylinder head, on which fasteners are employed to rigidly assemble this lower part of cylinder head with cylinder block in such a way that there is enough space provided for servicing/"assembly/dismantling of assembly of cam train and tappet adjustments. The time required for assembly or servicing of valve train or adjusting the timing of cam train and tappet clearances is also significantly minimized. In the said semi¬circular recess of said lower part of cylinder head, a cam shaft axial stopper provided is snugly fitted to provide a cover for the said recess as well as to prevent any axial movement of said cam shaft away from its bearing housing. The cylinder head for an overhead cam operated internal combustion engine , according to this invention comprises a lower part and an upper part; the lower part accommodating components including the cam shaft, rocker arms, cam driven sprocket, valve assembles and spark plug(s); characterised by the upper part seating itself on a ledge, provided all around the external periphery of the lower part, to provide a cover for the lower part, said ledge being located at a predetermined level below the top surface of the cam shaft bearing housing; a recess provided on the side wall of the lower part, in alignment with the cam bore of the lower part, the mouth of the recess being flush with the ledge and of size facilitating assembly of the cam shaft and machining of the cam bore, said recess receiving a stopper in snug fit so as to provide a cover for the recess, while a button on the stopper is closely disposed to the end tace of the cam driven sprocket and thus results in arresting any axial movement of the cam shaft away from the bearing housing, the stopper being firmly held in place within the recess whenever the upper part is placed on the lower part and fastened thereto. This invention will now be described with reference to the accompanying drawings which illustrate by way of example and not by way of limitation one of various embodiments of this invention wherein Figure 1 an exploded pictorial view of a preferred embodiment of an overhead cam cylinder head for a single FIGURE 2 FIGURE cylinder 4-stroke internal combustion engine according to this invention; shows a pictorial view of the lower part of said cylinder head with the assembly of valve train according to this invention and shows a full pictorial view of said cylinder head lower part of this invention. The embodiment illustrated will be seen to comprise a lower part 1 and an upper part 2. The lower part accommodates the cam shaft 5, rocker arms 7 and 8 for both inlet and exhaust, cam driven sprocket 6, rocker arm pivot pins/bushes 9A, 9B and lOA, lOB, a spark - and part of timing chain passing over the said cam driven sprocket. Inlet and exhaust valve assemblies 3 and 4 consist of known parts. The upper part 2 seats itself on a ledge 11, provided all around the external periphery of the lower part, to provide a cover for the lower part, said ledge being located at a predetermined level below the top surface 12 of the camshaft bearing housing 13, such that the accessibility or space availability is sufficient for dismantling, assembling or servicing the components accommodated in the lower part 1. The top surface 12 of the cam shaft bearing housing 13 is used for seating fasteners for rigidly fitting the lower part 1 with the cylinder block. Fasteners are used through the ledge 11 to firmly fit the upper and lower parts together. A semi-circular recess 14 is provided on the side wall of the lower part 1, the mouth of the recess being flush with the ledge 11. The said recess receives a semi-circular stopper 15 in snug fit to provide a cover for the recess. A button P on the stopper 15 is closely disposed to the end face of the cam driven sprocket 6 and thus results in arresting any axial movement of the camshaft away from its bearing housing. The axis of the semi-circular recess 14 is concentric with the cam bore of the lower part 1 and stropper 15, the size of the said recess being sufficient to permit easy assembly of the integrated cam shaft in the lower part and also to permit the cam shaft bearing housing to be machined by any known process which is simple, easy, cost effective and reliable for achieving geometric accuracies. The stopper is firmly held in place Within the recess whenever the upper part 2 is placed on the lower part 1 and fastened thereto. The recess 14 has a groove G along its peripheryi The stopper has a beading at E along its edge, mating with the groove G, which serves as a seal when the stopper is seated in the recess. The beading is in the form of an elastomer lining resistant to oil, petrol and temperature. The elastomer lining also dampens noise. The ledge 11 is located in a plane passing through the axis of the cam bore of the lower part so that the assembly and disassembly of the semi-circular stopper 15 is rendered easy. The button P is provided With a slot on one side at R. This slot helps to direct the flow of oil on the cam chain. The terms and expressions herein are of description and not of limitation, such terms and* expressions not excluding any equivalents of the features illustrated and described, as it is understood that various other embodiments of the cylinder head proposed herein are possible without departing from the scope and ambit of this invention. We Claim; 1. A cylinder head for an overhead cam operated internal combustion engine, comprising a lower part and an upper part; the lower part accommodating components including the cam shaft, rocker arms, cam driven sprocket, valve assemblies; and spark plug(s); characterised by the upper part seating itself on a ledge provided all around the external periphery of the lower part, to provide a cover for the lower part, said ledge being located at a predetermined level below the top surface of the cam shaft bearing housing; a recess provided on the side wall of the lower part, in augment with the cam bore of the lower part, the mouth of the recess being flush with the ledge and of size facilitating assembly of the cam shaft and machining of the cam bore, said recess receiving a stopper in snug fit so as to provide a cover for the recess, while a button on the stopper is closely disposed to the end face of the cam driven sprocket and thus results in arresting any axial movement of the cam shaft away from the bearing housing, the stopper being firmly held in place within the recess whenever the upper part is placed on the lower part and fastened thereto. 2. A cylinder head as claimed in claim 1 wherein the ledge is located in a plane passing through the axis of the cam bore. 3. A cylinder head as claimed in Claim 1 or Claim 2 wherein the recess has a groove along its periphery, and the stopper has a beading along its edge, mating with the groove, to serve as a seal when the stopper is seated in the recess. 4. A cylinder head as claimed in Claim 3 wherein the beading is in the form of an elastomer lining resistant to oil, petrol and temperature. 5. A cylinder head as claimed in any one of the preceding Claims wherein the button has a slot on one side to direct the flow of oil on the cam chain. 6. A cylinder head for an overhead cam operated internal combustion engine substantially as herein described and illustrated with reference to the accompanying drawings.

Documents:

0212-mas-2002 abstract.pdf

0212-mas-2002 claims-duplicate.pdf

0212-mas-2002 claims.pdf

0212-mas-2002 correspondence-others.pdf

0212-mas-2002 correspondence-po.pdf

0212-mas-2002 description (complete)-duplicate.pdf

0212-mas-2002 description (complete).pdf

0212-mas-2002 description (provisional).pdf

0212-mas-2002 drawings.pdf

0212-mas-2002 form-1.pdf

0212-mas-2002 form-19.pdf

0212-mas-2002 form-26.pdf

0212-mas-2002 form-5.pdf

212-mas-2002 abstract-duplicate.pdf

212-mas-2002 assignment.pdf

212-mas-2002 drawings-duplicate.pdf

212-mas-2002 form-2.pdf

212-mas-2002 form-4.pdf

212-mas-2002 form-6.pdf

212-mas-2002 others.pdf

212-mas-2002 petition.pdf