Machine element or mechanism – Mechanical movements – Rotary to or from reciprocating or oscillating
Patent
1989-06-28
1991-04-02
Braun, Leslie A.
Machine element or mechanism
Mechanical movements
Rotary to or from reciprocating or oscillating
123179R, F16M 2118
Patent
active
050038320
DESCRIPTION:
BRIEF SUMMARY
SUMMARY OF THE INVENTION
The present invention relates to motion transmitting mechanisms for use in heat engines, refrigerating machines and heat pumps, hermetically sealed or provided with rotary shaft seals and operating according to the external heat supply principle and the heat removal principle, respectively, in compliance with the Stirling, Ericsson or similar thermodynamic cycles. These machines are enclosed in a hermetic casing with or without rotary shaft seals and are pressurized by a working medium suited for their function, preferably helium or hydrogen gas. A common feature of these machines is that their proper function relies on a system of heat exchangers which must necessarily be protected from oil contamination preventing heat transfer. In view hereof, the motion transmitting mechanisms included must either be lubricated by systems of circulating or splashing oil which are then separated and sealed from the heat exchangers and the reciprocating pistons associated therewith by means of complicated dynamic linear sealing devices, or, which is preferable, be provided with motion transmitting mechanisms which operate without circulating and splashing lubricating oil and, thus, do not require the above-mentioned dynamic sealing devices for the lubricating oil.
The motion transmitting mechanisms for the above-indicated machines have a number of functions integrated therein which must be maintained to ensure satisfactory operation of the machines: the thermodynamic process; the pistons, e.g. from the connecting rods in a crank mechanism, which would necessitate lubrication with circulating or splashing lubricating oil; to another part thereof which absorbs energy; to avoid vibrations.
The machines indicated above are generally divided into kinematic machines and free-piston machines, as well as an intermediate form which may be referred to as semifree piston machines. All these machines may serve in different contexts as heat engines, refrigerating machines and heat pumps, depending on the design and mode of operation of the thermodynamic system. The need of motion transmitting mechanisms is felt primarily in kinematic and semi-free piston machines while true free-piston machines generally function properly without any motion transmitting mechanism.
Kinematic machines have hitherto been dependent on circulating or splashing lubricating oil systems, necessitating complicated and operationally sensitive linear sealing devices. The risk of oil leakage from the motion transmitting mechanism of the machine to the piston and heat exchanger unit has so far been an embarrassing obstacle to a successful commercial use of kinematic machines.
Semi-free piston machines transmit the working forces from reciprocating so-called working pistons to components of the system which, also by a reciprocating movement, absorb the generated forces, or transmit working forces from a reciprocating movement in a power source to reciprocating pistons absorbing energy. These functions are ensured by linear movements which do not require any motion transmitting mechanism. On the other hand, a motion transmitting mechanism is required for guiding non-working or work-absorbing pistons, so-called displacement pistons. Since the required forces to be transmitted in such a motion transmitting mechanism are comparatively very small, it is possible to use bearings with limited, sealed grease lubrication, even if the motion transmitting mechanism is also used for completely or partly counterbalance mass forces of inertia in the system to avoid vibrations. To this end, relatively complicated and expensive motion transmitting mechanisms of the so-called rhombic gear type have been considered necessary to fulfil these functions in an adequate way.
As mentioned above, a successful commercial use of kinematic machines or semi-free piston machines has not been possible because of the lack of a simple and inexpensive motion transmitting mechanism which can operate during a long period of time without the need of circulating or splashing
REFERENCES:
patent: 2229788 (1941-01-01), Appleton
patent: 4138897 (1979-02-01), Ross
Anchell Scott
Braun Leslie A.
Stig G. Carlqvist Motor Consultant, (C.M.C.) Aktiebolag
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