Internal-combustion engines – Multiple piston – common nonrestrictive combustion chamber – Four-cycle
Patent
1996-09-27
1998-03-03
Okonsky, David A.
Internal-combustion engines
Multiple piston, common nonrestrictive combustion chamber
Four-cycle
123 51BB, 123 525, F02B 2512
Patent
active
057223556
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a twin-piston engine, i.e. a crankcase scavenged two-stroke internal combustion engine comprising two pistons travelling in essentially the same direction, and wherein one of the cylinder bores, the exhaust cylinder bore, contains exhaust ports, and the other cylinder bore, the scavenger cylinder bore, contains a number of scavenging ports.
2. Description of Related Art
So called twin-piston engines have been known for some time. Since the scavenging ducts and the exhaust duct are positioned in a different one of the cylinder bores, the scavenging gas losses in the exhaust port are smaller than in conventional two-stroke engines. The result is lower fuel comsumption and cleaner exhausts than in the case of a conventional two-stroke engine. However, it is known that this advantage is greatest when the delivery rates are low. The delivery rate is the amount by weight of scavenging gas supplied to the combustion chamber divided by the maximum amount by weight of scavenging gas that may be contained in the combustion chamber. Higher delivery rates thus result in increased engine power. For this reason it is desirable to provide for low fuel consumption also when the delivery rates are those normally found in a two-stroke engine. A reduction of the engine scavenging losses leads both to a lower fuel consumption and to considerably reduced exhaust emissions.
In portable utility appliances crankcase scavenged engines are used as a rule because their lubricating system is independent of position and handling. It is a great deal more difficult to create an efficient enaging design in the case of crankcase scavenged double-piston engines than in the case of non-scavenged engines. This is due to the fact that the scavenging ducts from the crank-case compete with the suction port for the available space in the cylinder wall when that port is positioned in the scavenging cylinder bore, a position which is often desirable. The difficulties are most pronounced when open scavenging ducts, such as diecast scavenging ducts, are used. Examples of twin-piston engines of the non-crankcase scavenged type are provided by U.S. Pat. Nos. 1,476,305; 1,968,524; and 1,777,478.
Prior-art crankcase scavenged twin-piston engines often have a complex and bulky construction while at the same time the fuel efficiency leaves a great deal to be desired. In addition, they are difficult to manufacture in a rational way and their suction and exhaust ducts are often placed in closely adjacent relationship, resulting in unsuitable heating of the suction side. Examples of such prior-art twin-piston engines are found in U.S. Pat. Nos. 1,265,596, 1,542,697, DE 573 297, and DE 570 786. These publications show arrangements wherein the suction and exhaust ducts are positioned closely adjacent each other, positioned in the same cylinder bore, V-shaped cylinder bores, etc.
SUMMARY OF THE INVENTION
An object of the present invention is to substantially reduce the problems in the art by providing a twin-piston engine of a simple and purposeful construction which exhibits a high fuel efficiency, particularly at delivery rates that normally are found in a twostroke engine.
In accordance with the present invention all suction ports of the engine are positioned in the scavenging cylinder bore. A fuel supply device, such as a carburettor, is connected to the suction port/ports and is positioned essentially on the line of extension passing through the cross-sectional center of the two cylinder bores. The exhaust port is positioned essentially in alignment with the extension of that same line in the opposite direction. The mouth of the exhaust port debouching on the external face of the cylinder is provided with an essentially direct-mounted muffler whereby the fuel supply device and said muffler will be positioned on opposite sides of the cylinder body. The following reasoning is applicable with respect to an engine that corresponds to a conventional single-cylinder two-st
REFERENCES:
patent: 1476305 (1923-12-01), Toth
patent: 1602058 (1926-10-01), Violet
patent: 2014771 (1935-09-01), Mallory
patent: 2048243 (1936-07-01), Zoller
patent: 2133510 (1938-10-01), Hallett
patent: 2164451 (1939-07-01), Fast
patent: 2168096 (1939-08-01), Ehrlich
patent: 2234918 (1941-03-01), Linthwaite
patent: 2295120 (1942-09-01), Maw
patent: 2342900 (1944-02-01), Sandell
patent: 2706970 (1955-04-01), Rinne
patent: 4079705 (1978-03-01), Buchner
patent: 4275689 (1981-06-01), Ray
patent: 4296714 (1981-10-01), Buchner
Ekdahl Roy
Larsson Lars
Aktiebolaget Electrolux
Okonsky David A.
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