Ae Plc

Roger A Day

Robert Munro

Gordon L Allen

Norman Tommis

Andrew R Baker

A piston is manufactured by incorporating a reinforcement which is formed at least in part by a fibre material and which is so non-uniform as to provide differing characteristics in the cast piston in predetermined differing regions of the piston. For example, the volumetric density of the fibres may be different in one region of the reinforcement as compared with another region in order to produce a more resistant region in the cast piston. Additionally or alternatively, the reinforcement may hold finely divided materials which combine with the piston material during casting to give improved properties. Examples of this are the incorporation of particles of silicon, silicon carbide or silicon nitride to improve wear and/or the incorporation of molybdenum disulphide and tungsten disulphide or graphite to improve lubrication.

Reinforced pistons

A reinforced piston is provided for an internal combustion engine. The uppermost piston ring groove is as close as possible to the crown of the piston. At least the lower surface of the groove is defined by an en-cast insert and overlying this is a portion of the crown reinforced by fibres, thus allowing this portion to be thin and the spacing between the ring groove and the upper surface of the crown to be minimized. The reinforced crown portion also holds the insert against axial separating movement. The crown can be provided with a combustion bowl whose entrance is reinforced by the fibres.

A process is provided for pressure casting a piston with a crown insert and a cavity. The process comprises casting crown down in a mould and, before casting, placing in the mould means for forming a crown insert and a soluble salt core forming a cavity in the piston. The salt core is held by the crown insert means to position the salt core in the mould so preventing the salt core moving during pressure casting.

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Lymington, United Kingdom

Roger A Day