You can freely build on How the 1940 Nachumsohn Cooking Apparatus Works
This patent expired in 1957. 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
Individual
Patent granted
1940
Expired
1957
Forward citations
31
What this patent covers
The patent describes a cooking apparatus featuring a specialized chamber designed to contain food while applying heat from a controlled source. It focuses on the structural arrangement of the heating elements relative to the food container to ensure uniform temperature distribution. By managing the airflow and heat retention within the housing, the device aims to cook items more consistently than open-flame methods available at the time.
What is now free to use
All 0 claims of US 2187888 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 modern induction heating technology.
Does not cover digital temperature control or programmable timers.
Does not cover microwave-based cooking mechanisms.
Does not cover convection fans or forced-air circulation systems.
Who is building on this today
Modern kitchen appliance manufacturers like Breville and Cuisinart continue to iterate on the fundamental principles of enclosed thermal cooking. While this specific patent has long expired, its focus on chamber geometry remains a baseline for current oven design.
Products built on expired version of this technology
Early electric roaster ovens
Vintage countertop heating appliances
How to cite this patent in your documentation
Individual. US Patent 2187888. Cooking apparatus. Granted 1940, expired 1957. 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.