TAILIEUCHUNG - Newnes Sensor Technology Handbook 2005 Yyepg Lotb Part 7

Tham khảo tài liệu 'newnes sensor technology handbook 2005 yyepg lotb part 7', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Chapter 9 A number of commercial inductive proximity sensors are also available based on this general technique some miniaturized for robotic applications. An important but different sort of phenomena can be present if the metal object used to modify the inductance is a ferromagnetic material. Ferromagnetism is an effect in which the magnetic moments of the bound electrons and the nuclei also interact with external fields. In a ferromagnet the orientation of the magnetic moments in the material can become aligned with external fields causing an effective field amplification which can be very large. In addition this internal alignment can persist after the external field is removed or even if its direction is changed. Because the field amplification may be as much as 1000 times the presence of ferromagnetic materials greatly increases the sensitivity of inductance coil bridges to their presence. Therefore such sensors are very much more sensitive to ferromagnetic objects and one often sees sensors which are tuned to detect a small piece of ferro-magnet attached to a moving metal part. A very common example of the use of a ferromagnetic element is as shown in Figure . In this system the amount of magnetic field from one coil that is directed towards part of a second coil is dependent on the position of a ferromagnetic element. In the system shown in the drawing the two halves of the pick-up coil wired to Vout are wound in opposite directions. If the ferromagnet were not present the flux in each half of the pick-up coil would be equal and opposite and Vout would be zero. When the ferromagnet is positioned in the middle there is also a complete cancellation of the flux. However whenever the ferromagnet is displaced the flux balance is changed and the net effect is that there will be a voltage across the pickup coil whose amplitude is proportional to the displacement of the ferromagnet from its center position. Figure Inductive sensor circuit diagram. 230 .

TỪ KHÓA LIÊN QUAN
Đã phát hiện trình chặn quảng cáo AdBlock
Trang web này phụ thuộc vào doanh thu từ số lần hiển thị quảng cáo để tồn tại. Vui lòng tắt trình chặn quảng cáo của bạn hoặc tạm dừng tính năng chặn quảng cáo cho trang web này.