Patents by Inventor David Roy Withers

David Roy Withers has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 5644280
    Abstract: A method of operating a two-coil solenoid valve of the type including an armature member located in a housing for movement between a first electromagnet and a second electromagnet, each electromagnet being located adjacent to a respective end of the armature member and being switchable between an on state and an off state. In order to move the armature member from a first position closely adjacent to the first electromagnet to a second position closely adjacent to the second electromagnet, the electromagnets are controlled to be at the same initial switched state and subsequently one of the electromagnets is switched to the other switched state for a first predetermined period sufficient to allow the resultant pull exerted on the armature member to be such that the armature member is caused to move towards the second electromagnet.
    Type: Grant
    Filed: December 22, 1994
    Date of Patent: July 1, 1997
    Assignee: Perkins Limited
    Inventors: Colin John Wilson, David Roy Withers, Ewan Stuart Bewley