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:
Sep. 21, 1999
Filed:
Mar. 26, 1998
Applicant:
Inventor:
Kuldip Raj, Merrimack, NH (US);
Assignee:
Ferrofluidics Corporation, Nashua, NH (US);
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H01F / ;
U.S. Cl.
CPC ...
335277 ; 335257 ; 335279 ; 335280 ; 335281 ; 335229 ; 335234 ;
Abstract
A solenoid includes a ferrofluid in gaps between the moving and stationary elements which ferrofluid reduces noise caused by activating a plunger positioned within the solenoid. A permanent magnet can be included as a solenoid element to increase magnetic field strength within the solenoid to retain the ferrofluid within the solenoid. A cushion located between the plunger and a butt toward which it moves also reduces the noise, while the ferrofluid maintains a relatively high solenoid force relative to a solenoid with air gaps.