3688512 is referenced by 9 patents and cites 4 patents.

A cold-gas machine includes first and second pistons for varying the volumes of a cold and a warm space; the first piston has a seal and a duct which communicates with a buffer space, the latter communicating via a duct with the warm space, debouching at a place situated between the axial boundaries of said seal. A non-return valve opens in the direction of the warm space is incorporated in this duct.

Title
Cold-gas refrigerator, displacer seal to reduce frozen contaminants
Application Number
05/100,662
Publication Number
3688512
Application Date
December 22, 1970
Publication Date
September 5, 1972
Inventor
Hendrik Jan Rauwerdink
Gijsbert Prast
Agent
Frank R Trifari
Assignee
US Philips Corporation New York NY
IPC
F25b 09/00
F25B 09/14
View Original Source