The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 11, 2000
Filed:
Mar. 24, 1998
Applicant:
Inventor:
Terence E Crimmins, Northport, NY (US);
Assignee:
The Chamberlain Group, Inc., Elmhurst, IL (US);
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H01H / ;
U.S. Cl.
CPC ...
361170 ; 361 51 ;
Abstract
A fire door opener and method of electronically controlling the door descent speed is described. The operator includes a DC brake solenoid coupled to an AC motor drive system with an inline gear reducer and an electronically controlled descent device with battery backup power. If the brake is disengaged, the door will drop by overcoming the internal inertia and friction in the inline gear reducer. Speed of descent is controlled electronically by measuring the descent speed of the fire door at its limit shaft and electrically modulating the brake engagement using the DC solenoid.