| 主权项 |
1. A method for indicating the position of a valve, comprising the steps of:
keying an indicator shaft to a valve shaft for rotation with the valve shaft, wherein said indicator shaft and said valve shaft have the same axis of rotation, said indicator shaft having first and second ends and a mechanical visual position indicator secured to said first end, keying a magnet to said indicator shaft for rotation with said indicator shaft, said magnet having a north pole, a south pole, and a polar axis, with the polar axis directed perpendicular to and through said axis of rotation, mounting a magnetic pole sensor in a first fixed position adjacent said indicator shaft, said magnetic pole sensor including means for providing an output indicating the polarity of the magnet, mounting a magnetic field sensor in a second fixed position adjacent said indicator shaft, said magnetic field sensor including means for providing an output that correlates to the angular position of the magnet, using said magnetic pole sensor to sense the polarity of said polar axis when the valve is in a known position, establishing first and second algorithms for correlating the output of the magnetic field sensor with the angular position of the valve depending upon the polarity of the polar axis when the valve is in that known position, selecting one of said first and second algorithms based on that sensed polarity, applying the selected algorithm to determine the position of the valve as the valve is opened and closed, and providing an output indicating the position of the valve, wherein said magnet is a diametrically magnetized ring magnet defining a central opening, and the step of keying the magnet to the indicator shaft includes extending the position sensor shaft through said central opening. |
