Method and apparatus for detecting the position of a piston of a piston cylinder through the use of microwaves

US9175700B2 · kind B2 · utility

Assignee

• BALLUFF GMBH · DE

Inventors

• Josef Buechler · Brackenheim, DE
• Sorin Fericean · Leonberg, DE
• Albert Dorneich · Scharnhauser Park, DE
• Markus Fritton · Bad Liebenzell, DE

Key dates

• Filing date: Jun 28, 2012
• Grant date: Nov 3, 2015
• Expiry date: May 12, 2034

Classification

• Technology area (CPC G): Physics
• CPC primary: G01S13/88
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A method for detecting the position of a piston of a piston cylinder is provided. A microwave transmit signal is emitted in the direction of the piston and microwaves reflected from the piston are detected. The transmit signal is a modulated signal with a base frequency sinusoidally modulated at a modulation frequency. An evaluation of the phase between transmit signals and receive signals is performed. A phase determination at the baseband and a simultaneous phase determination at at least one sideband are also performed. The phase determination at the baseband is used for fine determination of the piston position and the phase determination at the at least one sideband is used for coarse determination of the piston position. Bandpass filtering on receive signals and evaluation transmit signals is performed with respect to the base frequency or an intermediate frequency. Bandpass filtering is performed with respect to the modulation frequency.