Rotary expansible chamber devices – Working member has planetary or planetating movement
Patent
1995-01-12
1997-10-28
Vrablik, John J.
Rotary expansible chamber devices
Working member has planetary or planetating movement
418 60, 418 611, 418122, 418123, 418129, F01C 102, F01C 1706, F01C 1904
Patent
active
056811560
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a piston machine constituting an expansion engine, suction pump or compressor for a compressible medium having a piston mounted in a working space on crank pins of at least two identical, rotatably mounted crankshafts which are angularly synchronously coupled.
BACKGROUND OF THE INVENTION
Such a piston machine is known from US-A 1864699. The chamber surfaces on the chamber wall and on the piston which define the working chambers are composed in this construction of sliding surfaces of cylindrical segment shape which are in engagement with a sealing element in the form of a sealing strip and of relatively large flat surfaces. When the sealing strips engage, chambers are produced with very large surfaces which are substantially determined by the flat surface portions. The construction is similar to a lifting cylinder machine without a connecting rod.
A disadvantage of this known construction is the very large ratio of the chamber surface to the chamber volume, which is desirable due to its use as a steam engine and which is thermodynamically extremely unfavorable for use as a combustion machine or compressor. Another disadvantage in this construction is the variation of the force acting on the piston at differing crank angles. Since the piston area alters only slightly at different crank angles, the force acting on the piston remains virtually constant. This is unfavorable not only in use as a combustion machine but also, in particular, when used as a compressor since the piston loading becomes extremely high. Also disadvantageous is the angle at which the resulting force acting on the piston acts upon the crankshaft. Angles in the region of 90.degree., which result in a high torque at low bearing loads, would be desirable. In the known construction this angle of action of the force always extends, however, substantially perpendicular to the relatively large flat surface of the piston. The circumstances are similar to those in a lifting piston in which the force can only be transferred to the crank at a favorable angle of action over only a very small range of crank angles.
SUMMARY OF THE INVENTION
An object of the present invention resides in providing a piston machine of the type referred to above which may be improved thermodynamically and as regards the force variation and the angle of action of the force.
In accordance with the invention, when the chamber is becoming smaller the sealing element on the piston defining the chamber moves over the sealing element on the peripheral wall defining the chamber. When the volume of the chamber approaches zero its surfaces thus also approach zero. The result of this is a substantially constant ratio of the chamber surface to the chamber volume with very good thermodynamic characteristics, particularly as regards the heat losses at the surfaces when the chamber volume is small, that is to say at maximum compression. This results also in a substantially constant force being introduced into the piston since as the compression pressure increases the loaded piston area becomes constantly smaller. Overloading of the machine is thus prevented even at the highest compression. Combustion machines or compressors of extremely high compression may thus be realized. The force resulting on the piston is always substantially perpendicular to the line connecting the sealing elements defining the chamber. This alters its angle such that the direction of the resulting force is substantially perpendicular to the crank over a very large angular range of the crank, particularly when the chamber volume is relatively large. The result of this is very smooth, uniform movement and, with combustion machines, high torque. Furthermore, more compact construction of the piston machine is made possible by the more compact construction of the working chambers which are formed. These advantages are added to the advantages inherent in this type of construction which operates with low vibration due to the parallel rotation principle and makes hi
REFERENCES:
patent: 1864699 (1932-06-01), Varley
Farley Walter C.
Vrablik John J.
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