CSIR Technology Portal
CSIR Technology Portal

 Patent Profile

Patent No: IN289653 [India] Application No: 0449DEL2009
Title: An Improved Speedometer
Issue Date: 16-11-2017 File Date: 09-03-2009
Inventor(s): PRASANTA CHOWDHURY, ARUN VENKATESH AINAPUR, HARISH CHANDRA BARSHILIA, KARAIKUDI SANKARANARAYANA RAJAM
IPC Classification: G01P 3,495
Abstract: Sensors referred in prior state of art related to speedometer are used to sense the magnetic field value not the field gradient. Measurement of field gradient is important considering the continuously changing air gap between magnetically coupled rotating elements (magnetic encoder) and sensing device (magnetic sensor) due to some artifacts in rotating element. Field gradient based measurement provides uniform signal output as it is independent of actual field value, which changes due to change in air gap. An improved speedometer of the present invention measures the field gradient which comprises magnetic encoder housing, GMR based magnetic sensor, signal conditioning circuit and microcontroller based controlled display unit. Even numbers of magnets are fixed in the annular cavity formed on the top surface of a circular plate by arranging them adjacent to each other with opposite polarity to form a multi-polar magnetic encoder. This magnetic encoder arrangement was then mounted concentrically on a rotating shaft, whose rotating speed to be measured. Magnetic sensor having two separate sensing elements to measure the field gradients is magnetically coupled to a magnetic encoder housing with an adjustable air gap by means of a micromanipulator. Output signal from the sensor is then converted to nearly square pulse in the signal conditioning circuit. Microcontroller based controlled display circuit processes the pulse output as a counter and displays parameters on display screen with the help of embedded software.
CSIR-National Aerospace Laboratories
CSIR-National Aerospace Laboratories[CSIR-NAL]
:  director[at]nal[dot]res[dot]in
:91-80-25086000
:https://www.nal.res.in
Industrial Applications Instrumentation, Appliances, Devices Applications [Instrumentation, Appliances, Devices] Magnetism [Physics] Measurement [Instrumentation, Appliances, Devices] Sensors [Electronics]