Position detection system

• US 20030030431A1
• Filed: 08/07/2002
• Published: 02/13/2003
• Est. Priority Date: 03/17/2000
• Status: Active Grant

• Current Assignee: Festo AG & Company KG (Festo GmbH & Company KG)
• Original Assignee: Festo AG & Co.
• Inventors: Reininger, Thomas
• Granted Patent: US 6,919,719 B2
• Time in Patent Office: Days
• US Class Current: 324/207.2
• CPC Class Codes: F15B 15/2807 Position switches, i.e. means for sensing of discrete positions only, e.g. limit switches
• CPC Class Codes: G01D 18/00 Testing or calibrating apparatus or arrangements provided for in groups G01D1/00 - G01D15/00
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06

Abstract

A position detecting means comprising a sensor arrangement (14) for producing at least sensor signal in a fashion dependent on a body (11) moving past said means, the sensor signal or signals continuously changing on such movement past. The at least one sensor signal is compared with at least one reference value in a comparator arrangement (20), control means being provided for electronic setting of the sensor arrangement (14) by changing the reference value and the output signal of the comparator arrangement (20) forms the position signal (P) for detection of a relative position of the body (11) and the sensor arrangement (14). Accordingly it is possible for the arrangement (14) to be mechanically set in a relatively rough manner and fine adjustment may be performed by changing the reference value electronically.

Claims

1. A position detecting means comprising a sensor arrangement (14) for producing at least sensor signal in a manner dependent on a body (11) moving past the means, the at least one sensor signal changing continuously on such movement past the means, a comparator arrangement (20) comparing the at least one sensor signal with at least one reference value, control means being provided for electronic adjustment of the sensor arrangement (14) by changing the reference value and the output signal of the comparator arrangement (20) forming the position signal (P) for detection of a relative position of the body (11) and the sensor arrangement (14).

2. The position detecting means as set forth in claim 1, characterized in that the body (11) produces a magnetic field or possesses a magnet (13) for the production of such a magnetic field and that the sensor arrangement (14) comprises at least one magnetic field sensor (15 and 16), more especially a hall effect sensor.

3. The position detecting means as set forth in claim 1 on in claim 2, characterized in that the sensor arrangement (14) comprises at least two sensors, whose signals are converted in a signal processing circuit (19) into a signal dependent in a substantially linear fashion on the relative position of the body (11) and the sensor arrangement (14).

4. The position detecting means as set forth in claim 3, characterized in that one sensor signal is a sine signal and the other signal is a cosine signal.

5. The position detecting means as set forth in claim 4, characterized in that two magnetic field sensors (15 and 16) are arranged at an angle of 45 degrees in relation to one another.

6. The position detecting means as set forth in claim 5, characterized in that as magnetic field sensors two hall effect sensor bridge circuits are provided.

7. The position detecting means as set forth in any one of the preceding claims, characterized in that the comparator arrangement (20) possesses at least one window comparator or schmitt trigger, the two switching reference value being variable.

9. The position detecting means as set forth in any one of the preceding claims, characterized in that the control means possess an electrically settable potentiometer (21) or a signal memory means for the reference value and more especially a digital counter or a digital memory.

10. The position detecting means as set forth in any one of the preceding claims, characterized in that for setting the control means at least one manual operating element (22 and 23) is provided.

11. The position detecting means as set forth in any one of the preceding claims, characterized in that the setting of the control means and/or the setting of the reference value is remotely controlled by way of an electrical line (24), and more especially a bus, or in a wireless fashion.

12. The position detecting means as set forth in any one of the preceding claims, characterized in that the evaluating circuit (17) having at least one comparator means (20) constitutes a subassembly together with the sensor arrangement (14).

13. The position detecting means as set forth in any one of the claims 1 through 11, characterized in that the evaluating circuit (17) comprising at least the comparator circuit (17), and/or the control means are integrated in a manner separated in space from the sensor arrangement (14) and more particularly in a programmable control unit.

14. The position detecting means as set forth in any one of the preceding claims, characterized in that the body (11) is the piston of a piston and cylinder unit and the sensor arrangement (14) is integrated on the cylinder (10), more particularly in a longitudinally sliding manner, or in the cylinder (10).

8. The position detecting means as set forth in any one of claims, characterized in that the sensor arrangement (14) possesses several identical sensors or sensor combinations arranged one after the other in the direction of motion, whose signals are compared by means of a corresponding number of components of the comparator arrangement (20) with reference values, which correspond to the sensor signals at the relative position to be detected.