You can freely build on How Albert Einstein and Leo Szilard Designed a Silent Refrigerator
This patent expired in 1947. Every claim — 0 independent, 0 dependent — is now unenforceable. Anyone can use, reproduce, manufacture, sell, or offer for sale this technology without a license.
Original assignee
Electrolux Servel Corp
Patent granted
1930
Expired
1947
Forward citations
22
What this patent covers
The patent describes an absorption refrigerator system that eliminates the need for moving parts like pistons or electric motors, which were prone to failure and leaks in early refrigeration technology. It uses an electromagnetic pump to circulate a refrigerant fluid through a closed loop. By leveraging the interaction between an electric current and a magnetic field, the system moves the liquid coolant without any mechanical wear, aiming for a design that is silent and durable.
What is now free to use
All 0 claims of US 1781541 are in the public domain. Specifically:
The 0 dependent claims add narrowing limitations and are also free.
What is NOT covered
Patent expiry frees this specific invention. Separately-patented improvements made after expiry may still be protected.
Does not cover standard vapor-compression refrigerators that use traditional electric compressors.
Does not cover refrigerators using chemical refrigerants like Freon or modern hydrofluorocarbons.
Does not cover systems that rely on mechanical pumps or rotating fans to move coolant.
Who is building on this today
Modern research into electromagnetic pumps continues in specialized fields like nuclear reactor cooling and liquid metal battery technology, where moving parts are undesirable.
Products built on expired version of this technology
Experimental absorption refrigeration prototypes
Early silent cooling systems for laboratory use
How to cite this patent in your documentation
Electrolux Servel Corp. US Patent 1781541. Refrigeration. Granted 1930, expired 1947. Now in the public domain.
Note: This is a convenience citation. Consult a patent attorney for formal freedom-to-operate analysis.
PatentBrief is an educational resource and does not provide legal advice. Patent expiration information is derived from USPTO records and may not reflect continuation patents, divisional filings, or separately-patented improvements. For commercial use or production decisions, obtain a formal freedom-to-operate (FTO) opinion from a registered patent attorney.