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:
Aug. 03, 1993
Filed:
Jun. 21, 1991
Frank W Shacklock, Auckland, NZ;
Murray Greenman, Auckland, NZ;
Fisher & Paykel Limited, Auckland, NZ;
Abstract
The temperature or some other specific characteristic of a mixture of two liquids at different temperatures in a mixing chamber (14) is controlled by a microprocessor (8) which controls the supply of power to solenoid actuated valves (10 and 11) to control the quantities of the liquids admitted to the chamber (14) so that a desired temperature of the mixture is achieved using pulse width modulation control. The pulse width modulation control requires only one microprocessor timer and provides a substantially constant supply of power to one valve while varying the power supplied to the other valve to control flow through each valve and thus the temperature of the liquid mixture.