Internal-combustion engines – Two-cycle – Whirl through piston-controlled ports
Patent
1984-03-12
1987-03-24
Feinberg, Craig R.
Internal-combustion engines
Two-cycle
Whirl through piston-controlled ports
123 65A, F02B 7502
Patent
active
046516867
DESCRIPTION:
BRIEF SUMMARY
FIELD OF USE
The internal combustion engine according to the invention can be used whenever a high-speed, port-controlled, two-stroke internal combustion engine with crankcase scavenging is used as a high-performance motor, e.g. as a two-wheel drive, or as a choke motor, e.g. as a chain saw drive.
PRIOR ART
An internal combustion engine, particularly a high-speed, port-controlled, two-stroke internal combustion engine with crankcase scavenging is known from DAS No. 2,624,249.
Attempts have been made in connection with such an internal combustion engine to reduce the idling noise by modifying the outlet port geometry. Apart from the conventional outlet, additional auxiliary openings were provided and these and the outlet port were arranged in such a way that they satisfied given mathematical conditions. However, the known construction of the outlet port geometry for reducing noise has not proved satisfactory, because the greatest noise formation in the case of such two-stroke internal combustion engines occurs under full load and when idling, when the engine is operating at full speed, but without loading.
Attempts have also been made by using secondary measure to reduce the running noise of the engine. However, this led to disadvantageous effects on the performance or fuel consumption behaviour of the engines.
PROBLEMS, SOLUTION, ADVANTAGES
The present invention aims at providing a high-speed, port-controlled, two-stroke internal combustion engine in which, through a suitable construction of the inlet port geometry and/or outlet port geometry, it is ensured that the engine noise is reduced throughout its speed range, whilst maintaining the performance level and whilst simultaneously improving the specific fuel consumption.
Thus, to solve this problem, the invention provides a high-speed, port-controlled, two-stroke internal combustion engine with crankcase scavenging with at least one cylinder with in each case at least one suction duct with an inlet port, with in each case at least one outlet duct with an outlet port and with at least one scavenging duct with a transfer port, the inlet, outlet and transfer ports being located on the inside of the cylinder, characterized in that rectangular cross-section with an upper port boundary at right angles to the cylinder longitudinal axis and a lower port boundary at right angles to the cylinder longitudinal axis, as well as lateral port boundaries approximately parallel to the cylinder longitudinal axis, the cross-section being increased over and beyond the lower port boundary in the vicinity of the vertical median plane, and comprising a pre-inlet part and a post-inlet part upwardly following onto the latter in the cylinder longitudinal direction and having in the vicinity of the post-inlet part a substantially rectangular cross-section with a generally V-shaped channel in the vicinity of the vertical median plane and with upper port boundaries at right angles to the cylinder longitudinal axis and with lower port boundaries at right angles to the cylinder longitudinal axis, as well as lateral port boundaries running approximately parallel to the cylinder longitudinal axis and with a cross-section in the form of a geometrical shape in the vicinity of the pre-inlet part, the flow direction and which remains constant in its horizontal extension or uniformly decreases and having a generally V-shaped channel uniformly growing in the flow direction and extending in the region of the vertical median plane, and the flow direction and which uniformly varies in its vertical extension, and/or that rectangular cross-section with an upper port boundary running at right angles to the cylinder longitudinal axis and a lower port boundary running at right angles to the cylinder longitudinal axis, as well as with lateral port boundaries running approximately parallel to the cylinder longitudinal axis, the cross-section being widened over and beyond the upper port boundary roughly in the vicinity of the horizontal median plane, comprising a pre-inlet part and a post-inlet p
REFERENCES:
patent: 3945354 (1976-03-01), Johnston
patent: 4337734 (1982-07-01), Iio
patent: 4458636 (1984-07-01), Kania
Feinberg Craig R.
Okonsky David A.
Ruzek Peter R.
SACHS-Systemtechnik GmbH
Teltscher Erwin S.
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