Control-valve drive with sensor unit for detecting the position of the valve

• US 6,752,171 B1
• Filed: 02/19/2002
• Issued: 06/22/2004
• Est. Priority Date: 08/20/1999
• Status: Expired due to Fees

• Current Assignee: Samson AG
• Original Assignee: Samson AG
• Inventors: Schneider, Walter, Kemmler, Lothar, Kolbenschlag, Stefan
• Primary Examiner(s): CHAMBERS, A MICHAEL
• Application Number:
  US10/049,965
• Time in Patent Office: 854 Days
• Field of Search: 137/554, 137/552, 251/61.4
• US Class Current: 137/552
• CPC Class Codes: F15B 15/2861 using magnetic means
• CPC Class Codes: F15B 20/002 Electrical failure
• CPC Class Codes: F16K 37/0033 using a permanent magnet, e.g. in combination with a reed relays
• CPC Class Codes: G01D 5/147 influenced by the movement of a third element, the position of Hall device and the source of magnetic field being fixed in respect to each other
• CPC Class Codes: Y10T 137/8175 Plural
• CPC Class Codes: Y10T 137/8242 Electrical

Abstract

A drive for a control valve has a drive force unit, a yoke for connecting to a valve in a fixed manner, a drive spindle for transmitting the movement of the drive force unit to the valve and a sensor unit for detecting the position of the valve. The sensor unit includes a magnetic track with a reoccurring structure which is integrated into the drive spindle, a sensor which is connected to the yoke of the drive in the vicinity of the magnetic track, which is suitable for detecting the changing magnetic field lines and at least one permanent magnet in the area of the magnetic track and the sensor, whose magnetic field lines penetrate both the magnetic track and the sensor.

Claims

1. A drive comprising a drive force unit, a yoke for the fixed connection to a valve, a drive spindle for the transmission of the movement of the drive force unit onto the valve and a sensor unit for acquiring the valve position, the sensor unit being integrated in the drive spindle comprising a magnetic track having a periodic structure extending along the moving direction of the drive spindle, a pair of sensors connected to the yoke of the drive close to the magnetic track and being offset relative to one another along the moving direction, said sensors being suitable for the acquisition of changing magnetic field lines and at least one magnet in the region of the magnetic track and sensors, said magnet having magnetic field lines penetrating both the magnetic track and the sensors, the drive being coupled to the control valve, the magnet being a permanent magnet, the sensors being supplied with electrical auxiliary energy via an electrical auxiliary energy source, the sensors being connected to a unit for monitoring the electrical auxiliary energy of the source, an energy store for supplying the sensors with electrical energy, said energy store being connected to the sensors at least when an outage of the electrical auxiliary energy occurs so that the energy store makes it possible to continue the position measurement of the valve position, even during outage of the electrical auxiliary energy, for at least a predetermined time.

2. A drive according to claim 1, wherein the sensors are connected to a logic circuit and the logic circuit is connected to a timing unit which generates signals for the drive force unit after a characteristic time has passed given the outage of the electrical auxiliary energy, said signals forcing the drive spindle into a safety position.

3. A drive according to claim 1, wherein the drive spindle comprises an essentially constant outer diameter and an essentially smooth surface over at least the sub-region that contains the magnetic track.

4. A drive according to claim 1, wherein the drive spindle contains a permanent magnet.

5. A drive according to claim 1, wherein the sensors are connected to a permanent magnet on a side facing away from the magnetic track.

6. A drive according to claim 1, wherein the magnetic track is durably magnetic and the periodic structure is essentially formed by magnetic poles arranged at equal distance intervals.

7. A drive according to claim 1, wherein the drive spindle comprises a non-magnetic, metallic rod, whose metallic part is drawn down to a reduced diameter in a sub-region, and the rod is extrusion-coated in the sub-region with a plastic that has an outside diameter of the drive spindle essentially constant at least over the magnetic track.

8. A drive according to claim 7, wherein the plastic contains a ferritic filler that can be magnetized in order to form a magnetic track in the form of a plastic-bonded magnetic pole.

9. A drive according to claim 7, wherein the plastic is non-magnetic and fills out interspaces between periodic structures of the soft-magnetic material in order to form the magnetic track.

10. A drive according to claim 1, wherein the drive spindle comprises a hollow region into which a plastic is introduced so that the outside diameter of the drive spindle is essentially constant, at least over the magnetic track.

11. A drive according to claim 1, wherein the drive spindle comprises a hollow region, preferably in the form of an axial bore, into which a plastic-bonded magnet is introduced for forming the magnetic track.

12. A drive according to claim 1, wherein the drive spindle has a notch in the surface into which a plastic-bonded magnet terminating with the surface is provided for forming the magnetic track.

13. A drive according to claim 1, wherein the drive spindle is constructed of a soft magnetic rod having a series of notches selected from threads and teeth so that the magnetic track is prescribed by a structure of the notches.

14. A drive according to claim 1, wherein the drive spindle is surrounded by a thin wall, non-magnetic tube at least in the sub-region that contains the magnetic track.

15. A drive according to claim 1, wherein the sensors and the part of the drive spindle that carries the magnetic track are arranged essentially within a closed housing.

16. A drive according to claim 1, wherein the drive spindle is constructed of two parts, with one part of the drive spindle having the magnetic track being connected to a membrane and the other part of the drive spindle being connected to the valve, the yoke being fashioned in two yoke parts, whereby one yoke part essentially harbors the one drive spindle, carries the sensors and has covers to essentially close the housing for the magnetic track and the magnetic sensors.

17. A drive according to claim 1, wherein the sensors are connected to a memory unit of a microprocessor for monitoring and analyzing the changing magnetic field lines.

18. A drive according to claim 1, which includes a logic circuit which, when given return of the of the electrical auxiliary energy, generates signals for the drive force unit that moves the drive spindle over the entire working range and accepts initializing data.

19. A drive according to claim 1, wherein the drive spindle contains a trigger different from the magnetic track, said trigger causing a characteristic signal for a position of the drive spindle.

20. A drive according to claim 19, wherein the yoke carries an additional sensor for acquiring the position of the trigger.

21. A drive according to claim 1, wherein a safety position is a mechanical limit position determined by the trigger.

22. A drive according to claim 1, wherein the sensors are connected to an integrated circuit which is part of a position controller.

23. A drive according to claim 1, wherein the sensors comprise at least one magneto-resistive sensor.

24. A drive according to claim 23, wherein the pair of sensors are magneto-resistive sensors and comprise a plurality of magneto-resistive regions connected in the form of a Wheatstone bridge circuit that turn in different directions in the various branches.