Detection of a metal or magnetic object

Patent metadata

Field	Value
Publication number	US-9110122-B2
Application number	US-201113696355-A
Country	US
Kind code	B2
Filing date	Apr 15, 2011
Priority date	May 7, 2010
Publication date	Aug 18, 2015
Grant date	Aug 18, 2015

Abstract

A measuring device for detecting a metal object includes two emission coils configured to produce superimposed magnetic fields, a receiving coil in the region of both magnetic fields, and a control device configured to control the emission coils such that a value of a voltage, which is clock synchronized with alternating voltages and which is induced in the emission coils, is minimized. The control device is configured to detect the metal object when a ratio of the alternating voltages does not correspond to a ratio of distances between the receiving coils and the emission coils.

First claim

The invention claimed is:

1. A measuring device for detecting a metallic object comprising:
two transmitting coils configured to generate superimposed magnetic fields;
a receiving coil arranged in an area of the magnetic fields; and
a control device configured to supply the transmitting coils with alternating voltages such that a value of a voltage, which is clock-pulse synchronized with the alternating voltages and which is induced in the receiving coil, is minimized, wherein the control device is configured to detect the metallic object when a ratio of the alternating voltages does not correspond to a ratio of distances of the receiving coil from the transmitting coils.

2. The measuring device as claimed in claim 1 , wherein the alternating voltages are mutually phase-shifted to change the magnetic fields periodically in value and phase.

3. The measuring device as claimed in claim 1 , wherein the receiving coil is arranged symmetrically between the transmitting coils.

4. The measuring device as claimed in claim 3 , wherein:
at least one further receiving coil is arranged in the area of the magnetic fields; and
the control device is configured to supply the transmitting coils with voltage alternatingly based on a voltage induced in the receiving coil and a voltage induced in the further receiving coil.

5. The measuring device as claimed in claim 4 , further comprising an evaluating device configured to determine at least one of a direction, a distance, and a size of the metallic object based on the voltages induced in the receiving coil and the further receiving coil.

6. The measuring device as claimed in claim 4 , wherein at least one of the transmitting coils and the receiving coil is an air-core coil.

7. The measuring device as claimed in claim 4 , wherein at least one of the transmitting coils and the receiving coil is a printed circuit on a printed circuit board.

8. The measuring device as claimed in claim 7 , wherein the control device is constructed on the printed circuit board.

9. A method for detecting a metallic object, comprising:
generating superimposed magnetic fields with two transmitting coils;
determining a voltage induced in a receiving coil in an area of the magnetic fields;
supplying the transmitting coils with alternating voltages such that a value of a voltage, which is clock-pulse synchronized with the alternating voltages and which is induced in the receiving coil, is minimized; and
detecting the metallic object when a ratio of the alternating voltages does not correspond to a ratio of distances of the receiving coil from the transmitting coils.

10. A non-transitory computer readable medium that stores program code for performing a method when run on a processing device, the method comprising:
generating superimposed magnetic fields with two transmitting coils;
determining a voltage induced in a receiving coil in an area of the magnetic fields;
supplying the transmitting coils with alternating voltages such that the value of a voltage, which is clock-pulse synchronized with the alternating voltages and which is induced in the receiving coil, is minimized; and
detecting the metallic object when a ratio of the alternating voltages does not correspond to a ratio of distances of the receiving coil from the transmitting coils.

Assignees

• Zibold Tobias
• Albrecht Andrej
• Bosch Gmbh Robert

Inventors

• Zibold Tobias
• Albrecht Andrej

Classifications

• G01R33/0029

  Treating the measured signals, e.g. removing offset or noise · CPC title

• G01V3/107

  using compensating coil or loop arrangements · CPC title

• G01R33/091 Primary

  Constructional adaptation of the sensor to specific applications · CPC title

• G01V3/104 Primary

  using several coupled or uncoupled coils (G01V3/101 takes precedence) · CPC title