Internal-combustion engines – Precombustion and main combustion chambers in series
Patent
1996-07-24
1999-03-02
Dolinar, Andrew M.
Internal-combustion engines
Precombustion and main combustion chambers in series
123 543, 1231971, F02B 4102, F02B 7532
Patent
active
058757554
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to rotary machines and more particularly to internal combustion engines having linear piston motion producing a rotary output.
BACKGROUND ART
This invention is related to developments by the present applicant in connection with International Patent Applications PCT/AU89/00275; PCT/AU91/00244; PCT/AU94/00529and PCT/AU94/00569 the contents of which International patent applications are incorporated herein by reference and nominated as split-cycle arrangements. By employing lobed shafts as the means of transmission of linear piston motion to rotary output motion a wide range of varying piston motions can be achieved simply by varying the shape of the lobes. A particular advantage arises in that by appropriate designing of the profiles of the lobes on the shafts the pistons can be controlled in such a manner as to vary their dwell time at any position between top dead center and bottom dead center as well as at those limits of piston motion.
A particular advantage arises where the piston dwell time is extended at its top dead center position to facilitate combustion of the fuel charge while the piston remains at that location to enable maximum energy transmission to the piston and thereby achieve the best possible conversion of combustion energy to engine output power and torque.
In previous disclosures rotary machines of this form have contemplated the use of 50 mm diameter pistons having a 6 mm stroke. Typically the combustion chamber being the volume above the piston at top dead center within the cylinder and head of the engine or machine, has been sized at 2 mm high with a 50 mm bore.
With a 50 mm diameter piston and a 6 mm stroke the swept volume is approximately 11.8 cc for each cycle of motion of the piston while the head volume of the cylinder with the piston at top dead center is approximately 4000 cubic millimeters. The effective cubic capacity of the cylinder is, eg. 10.3 cc. being the swept volume of the cylinder after closing of the exhaust port slit in the cylinder's sidewall as the piston travels toward TDC.
DISCLOSURE OF INVENTION
Conventional engine technology leads to a combination of an oversquare engine design coupled with a high compression ratio in order to achieve improved engine output while the present inventive development has found that by reducing the compression ratio coupled with an appropriately designed dwell time at top dead center an improved engine output call be achieved. The dwell time is readily modified by varying the shape of the lobes on the lobed shafts of the split cycle engine.
In one example where the compression ratio was changed from 4 to 1 to 1.75 to 1 a marked increase in engine performance was achieved.
In the case of an embodiment with a 50 mm diameter piston and a 6 mm stroke with a 2 mm high combustion chamber it was varied so as to provide an 8 mm high combustion chamber at top dead center the compression ratio had thereby changed from 4.1 to 1.75 to 1 which was coupled to a dwell at top dead center equivalent to 72.degree. of crank rotation in a conventionally cranked engine. In this embodiment a marked increase in engine performance was achieved.
An analysis of the described embodiment shows that the volume of fuel and air charge in the lower compression ratio engine provided a charge volume at the top dead center of approximately 16,000 cubic millimeters with a compression ratio of 1.75 to 1 as compared with 4000 cubic millimeters in the engine with a compression ratio of 4 to 1 while the cylinder pressure at top dead center was reduced from 80 pounds per square inch for the 4 to 1 compression ratio engine to 50 pounds per square inch for the engine with a 1.75 to 1 compression ratio. The ratio of the charge volume for the 1.75:1 compression ratio engine to that of the 4:1 engine is 7:4 being the ratio of the combined cylinder and head volumes with their pistols at bottom dead center.
An analysis of the functional operation of the differences between these versions shows that considerably more fuel ene
REFERENCES:
patent: 326562 (1885-09-01), Hopkins et al.
patent: 1054615 (1913-02-01), Rauch
patent: 3687117 (1972-08-01), Panariti
patent: 4140090 (1979-02-01), Lindberg
patent: 4211190 (1980-07-01), Indech
patent: 4459945 (1984-07-01), Chatfield
Dolinar Andrew M.
Split Cycle Technology Limited
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