Internal-combustion engines – Particular piston and enclosing cylinder construction – Cylinder detail
Patent
1989-08-16
1990-08-21
Myhre, Charles J.
Internal-combustion engines
Particular piston and enclosing cylinder construction
Cylinder detail
123 9027, 123 904, 123 9041, F01P 102, F02F 128, F02B 7524, F02B 6102
Patent
active
049496875
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND AND SUMMARY OF THE INVENTION
The invention relates to an air-cooled single cross flow cylinder head motorcycle internal-combustion engines having a crankshaft pointing in the driving direction of the motorcycle
ft. This camshaft controls overhead inlet and outlet
through rocker arms. The engine has a scavenging direction which is approximately aligned with respect to charge cycle devices in the cylinder head and encloses an acute angle .alpha., with the axis of rotation of the camshaft
An internal-combustion engine of this general construction is known in DE-A-No. 27 03 520. The engine therein is a flat twin engine having cross-flow cylinder heads and a camshaft arranged in each cylinder head in parallel to the crankshaft and pointing into the driving direction. Each cylinder-head comprises one inlet and outlet valve which are arranged in a plane which is in parallel to the crankshaft and rises toward the outside. The camshaft, which is in parallel to the respective valve plane, acts upon the valves through rocker arms. The inlet and outlet duct of each cylinder head is arranged relative to the respective valve plane in such a manner that a scavenging direction exists which falls from the rear top of the engine toward the front bottom and which encloses an acute angle with the axis of rotation of the camshaft.
The above-described arrangement requires a timing case which is essentially placed on the cylinder head and disadvantageously enlarges the overall dimensions of the flat twin engine and also results in a center of gravity of the internal-combustion engine which is located higher above the road surface.
Furthermore, a V-2 engine having cross-flow cylinder heads is known from Volume 31b of the Third Edition of "Mitteilungen des Institutes for Verbrennungskraftmaschinen und Thermodynamik" (Information of the Institute for Internal-Combustion Engines and Thermodynamics) of the Technical University of Graz from Illustrations 9.4T 2f-2g/II. The valves of this engine are arranged in planes which are essentially in parallel to the respective scavenging direction. However, here all the valves are actuated by a single camshaft, arranged between the cylinders in the engine power section, in parallel to the crankshaft. This requires a expensively constructed transmission. Here valve levers are actuated by the camshaft through relatively long push rods and rocker arms arranged in the cylinder heads for the control of the valves. Because of the relatively high oscillating masses and a high elasticity in the transmission, a precise valve control is hardly possible with acceptable expenditures. This results, in addition to unfavorable fuel consumption and exhaust values construction, in a machine with a reduced performance and rotational speed. Furthermore in this arrangement, considerable mechanical noise is created for an air-cooled engine and this also require relatively short servicing intervals for the valves due to the valve play changes.
It is the object of the invention to provide an internal-combustion engine of the above-mentioned construction, without the above-mentioned disadvantages. The invention allows for a relatively stiff valve control in a small installation space. Here several identical valves are arranged in an area of the cross-flow cylinder heads which is well-cooled by the air stream. This object is achieved by having inlet and outlet valves arranged in planes which are essentially in parallel with respect to the scavenging direction of the engine and with the valve camshaft in driving connection with the rocket arms through hollow tappets arranged in the cross-flow cylinder head.
An advantage of the invention is that the valve camshaft can be arranged at a minimum distance and next to the valve arrangement. It uses transmission elements of a small or short construction. Thus a stiff valve drive is achieved while, on the whole, the installation space is small and the arrangement is compact.
Here where the internal-combustion engine is constructed as a flat twin engine with cylinde
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Patent Abstract of Japan Bank 8NR207 JP No. 96405 date 11/82.
Technische Universitat Graz (Germany) 1983.
Bayerische Motoren Werke Aktiengesellschaft
Lo Weilun
Myhre Charles J.
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