Patent GB-669349-A (GB)
Title: Internal-combustion engine
IPC: F02B75/32
Filed: 1949-04-22
Abstract: 669,349. Construction of crank-chambers and cylinders: driving-gear; valves and valve-gear. TRESILIAN, S. S. April 19, 1950 [April 22, 1949], No. 10695/49. Classes 7(ii) and 7(vi)  To permit operation. at normal mean piston speeds in a four-stroke, engine for motor vehicles having poppet valves and a piston stroke equal to or less than threequarters piston diameter, inertia forces in the valve gear are reduced by providing at least two inlet, and possibly two or more exhaust, valves to each cylinder. As shown, applied to an overhead-valve engine, two inlet valves 66a; 66b, Figs. 7 and 10, and a single exhaust valve 69 are employed opening into an L-shaped combustion .chamber in a detachable cylinder head 50, which is formed with a tunnel 50a mounting and enclosing the valve gear which comprises a chain-driven cam-shaft 52 operating the valves directly through rockers 58. Inspection covers 59, which may be light metal pressings, are provided. The inlet valves. 66a, 66b are served, by a single inlet passage from the manifold 65a. A sparking plug bore 72 is provided. Further to reduce reciprocating masses, the piston 20, Figs. 1 and 2, is of cast light alloy and is driven from a crank-pin 30 through pin-and-slot mechanism comprising a bronze or like split bearing block 28 sliding in transverse, guides 31 (which may have bonded iron or steel inserts as shown) in the piston 20, itself slidable in guideways 25 in a crankcase 26. The head of the piston 20 may be connected to its neck 22, which consists of spaced legs stiffened, as shown, by webs 39, 40, by countersunk screws or nuts. The cylinder 21 may be detachable from the crankcase 26, which is closed at the bottom by a sump 42 and has part. cylindrical side-bays 27 to accommodate the movement of the bearing block 28. Main crankshaft bearing blocks 35,. 36 are.secured to the crankcase crown by bolts 37, and the crankcase walls are stayed by the tie 41. A similar construction may be used with an opposed piston engine. As applied to a side-valve engine having a normal connecting rod assembly, a single exhaust valve 87, Fig. 12, parallel to the axis of the cylinder 90 and two inlet valves 86a, 86b inclined slightly relative. thereto are directly operated through tappets from a side-mounted cam-shaft, the inlet valves of adjacent cylinders being served by a single passage 91. In a modification applicable to an engine having four cylinders 90, Fig. 13, two inlet passages 91a each serve four inlet valves 86a, 86b, the exhaust valves 87 being served by passages 92a, 92b. According to the Provisional Specification (a) the rockers 58 for the inlet and exhaust valves respectively are mounted on separate spindles, (b) the piston 20 has a detachable bottom cover for assembly purposes, and (c) normal connecting-rod assemblies for use with engines accordisg to the invention may have roller big-end bearings, magnesium-base light alloy pistons and magnesium-base or aluminium-base light alloy connecting-rods or a deeply finned big-end construction of the kind in which the connecting-rod and bigend bearing cap have serrated interengaging faces and jointly provide a radially-thin bearing ring.