Internal-combustion engines – Two-cycle – Whirl through piston-controlled ports
Patent
1983-06-02
1984-09-11
Burns, Wendell E.
Internal-combustion engines
Two-cycle
Whirl through piston-controlled ports
123 65B, 123 65R, F04C 2300, F02B 3330, F02B 3338
Patent
active
044703805
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a charging and distrubuting device for two-stroke engine, and is particularly concerned with the use of a rotary piston compressor of the type which delivers the compressed working fluid through one of its shafts to feed air or an air/fuel mixture to the cylinders of a piston engine.
The use of positive displacement compressors for charging two-stroke engines is well known, and is a technique frequently used in connection with larger engines. The main types of compressors used have been: Roots blowers, oscillating vane compressors, and helicoidal screw compressors. There have also been various proposals for rotary sleeve valves to regulate the distribution of the charge to the cylinders.
The present invention provides a single device which will selectively deliver a compressed charge to a respective cylinder of an engine, and is capable of being controlled to regulate the amount of charge delivered. The present device has the advantages of being not only compact, simple and inexpensive, but also that of being easily controllable. The device is capable of reducing the pumping losses caused by throttling when the engine is running at low load.
The present device is also capable of serving as a balancing means to reduce engine vibration, by the incorporation of eccentric masses into its pistons, drive, or delivery apparatus.
The object of the invention is to provide a relatively simple and cheap alternative to crankcase charging in two-stroke engines, so as radically to improve scavenging and reduce pollution, to simplify crankcase construction and lubrication, and to reduce pumping losses by substituting a variable displacement compressor for the conventional control of the induced charge by throttling. Also engine balance may be improved by effectively incorporating a secondary balancing shaft in the engine as part of the charging device.
The present invention comprises a variable displacement rotary piston compressor of the type in which the compressed fluid leaves the compression chamber via one of the compressor shafts. This shaft is extended to form a rotating distributor tube, and is positioned so that it passes close to the cylinders of an engine. Axially spaced ports are formed in the wall of the distributor tube at locations corresponding to the cylinders, the ports being in intermittent fluid communication with the cylinders either directly or via short ducts.
The compressor is driven at engine speed, and thus each port opens and closes in the manner of a rotary sleeve valve to control entry of the charge to the cylinder. The system does not rely on the engine pistons to open and close the ports admitting charge to the cylinder, and thus the location of the inlet-port is not restricted to the lower cylinder wall but may even be in the cylinder head itself.
Clearly the pistons or distributor tube may be weighted to provide a mass balancing effect to the engine as a whole.
Two embodiments of the present invention will now be described with reference to the accompanying drawings, in which:
FIG. 1 is an end sectional view of an engine incorporating the present device, the section being taken on line I--I of FIG. 2.
FIG. 2 is a sectional view taken on line II--II of FIG. 1.
FIG. 3 is an end view showing the piston shapes of the rotary piston compressor.
FIG. 4 is an end view similar to FIG. 3 showing the charge regulating device.
FIG. 5 is an alternative configuration of the device, in which the distributor tube ports open directly into the cylinders.
Referring now to FIGS. 1 to 4, FIG. 1 shows how the compressed charge (or air in the case of an engine with direct fuel injection) is fed to the cylinders of an engine, each cylinder having inlet and exhaust ports in its cylinder wall. The compressed air or air/fuel mixture is conducted inside a distritutor tube 1 which rotates in the direction of arrow 2 at a velocity equal and opposite to that of crankshaft 3. A port 4 in the wall of the distributor tube 1 opens when its position coincides with the lower end of a transfer
REFERENCES:
patent: 1448167 (1923-03-01), Sweet
patent: 1869787 (1932-08-01), Trumble
patent: 2283694 (1942-05-01), Perrine
patent: 3723031 (1973-03-01), Brown
patent: 4137018 (1979-01-01), Brucken
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