Chapter 8 - Speed and Timing Sensors

Abstract

This chapter discusses the speed and timing sensors. The measurement of speed or position of a rotating shaft helps in the proper functioning of many types of machinery. Speed sensors, timing sensors, and encoders are used in applications such as automobile ignition controls, and exercise equipment. Differential speed sensors are used to determine the direction of rotation with an appropriate target. Knowing the direction in which a target is rotating makes it possible to track the angular position of the target. Accurately measuring the angular position of a shaft is very useful and is the basis for many types of precision positioning equipment. The most common way of determining the rotational direction is the usage of two separate sensors, sensing the same target at slightly different points. The chapter also discusses the vane switch, which can be used as a speed sensor. Vane switches can provide good unit-to-unit repeatability in their mechanical actuation points and so they can be used as automotive ignition timing sensors.