Circuit arrangement for the control of a ventilator

US5074281A · kind A · utility

Assignee

• Diehl GmbH & Co. · DE

Inventors

• Henry Fluhrer · Bretten, DE
• Erwin Potthof · Westerburg, DE

Key dates

• Filing date: Jan 31, 1991
• Grant date: Dec 24, 1991
• Expiry date: Jan 31, 2011

Classification

• Technology area (CPC F): Mechanical Engineering; Lighting; Heating
• CPC primary: F24C15/2021
• WIPO field: Thermal processes and apparatus
• WIPO sector: Mechanical engineering

Abstract

A circuit arrangement for the control of a ventilator, especially for a stream or vapor vent hood which is located above a cooking range, in dependence upon steam or vapor clouds which are drawn towards the ventilator. An ultrasonic transmission path having an ultrasonic transmitter and an ultrasonic receiver is located in front of the ventilator, with a receiving circuit demodulating the signal which appears at the ultrasonic receiver; wherein an evaluating or sample-and-hold circuit evaluates any fluctuations in the input signal encountered over a period of time and which are based on the presence of steam or vapor clouds in the ultrasonic transmitting path, and counts these signals within a time frame, and wherein a comparator circuit compares the result of the count with preset values and, in accordance therewith, activates the ventilator.