How and where can Hall effect rotary-position sensors be used?

Hall effect rotary-position sensors are designed to measure the angle position of a moving element by using a magnetic field instead of mechanical brushes or dials. They use a magnetically-biased, Hall effect integrated circuit (IC) that senses rotary movement of the actuator shaft over a set operating range. Rotation of the actuator shaft changes a magnet's position relative to the IC. The resulting flux density change is then converted to a linear output which can be used to provide feedback to either the operator or vehicle sub-system. Solid-state Hall effect technology provides non-contact operation. The internal section of the sensor uses a magnetic field, not a physical brush or wiper that is used in potentiometers. Wipers used in potentiometers can cause friction, which can reduce the product's life. Using non-contact magnetic Hall effect technology in a rotary-position sensor helps reduce the number of worn-out mechanisms, lowers actuation torque and extends the product's service life. So what are the specifications that design engineers should consider when choosing Hall effect rotary position sensors? The first is durability. It is vital to consider the type of environment in which the device will be used. For harsh environments, engineers should specify a package that meets IP67 qualifications for enhanced durability. This is especially important for vehicles and machines that are being designed to operate in harsh climates and environments. Operating life is another significant factor. How long is the device specified to operate? Clearly it is vital to check the product's data sheet to determine its documented cycle life. It may be better to have the sensor manufacturer perform this testing so that engineering staff do not have to spend time doing this testing work. Designers also need to ask whether to specify an integral connector. Two important advantages of designing in a sensor with an integral connector are its smaller size and extended life. An integral connected sensor can be smaller than the overall package size of a sensor that relies upon a pigtail connection. This enables developers to design and build smaller overall system packages. Use of an integral connector increases durability because pigtails are notoriously fragile. The question of EMI/EMC resistance is also critical. Radio waves of different frequencies can interrupt electronics. Automotive-grade EMI/EMC protection provides reliability in sensor performance against radio frequencies in the environment. Whether or not you can use a standardised I/O may also be a factor. Using industry-standard AMP termination, 32mm mounting pitch and universal pin-out styles may help you save time and money. A standard I/O can greatly simplify drop-in replacement because the mounting points, profile and pin-outs are similar to those of the incumbent device. Finally, it is important to ask how flexible the sensors for the design need to be? For instance, are you working with one power setting or should the sensor be able to work with a variety of input voltages. It could be beneficial to use position sensors that provide a wide span of operating voltages or ranges. A variety of operating ranges can provide design engineers with the resolution needed in the span of travel in many common applications. One application for which the Hall effect rotary position sensor is particularly suitable is in heavy-duty vehicle equipment. For instance, they may be used to replace the mechanical cable connection between the foot pedal and the engine. A mechanical cable can stretch or rust, potentially requiring regular maintenance and recalibration. Eliminating the mechanical cable can improve the engine control system response, benefitting the vehicle's emission, improving reliability and reducing excess weight. This type of drive-by-wire system can be both safer and less expensive than cable-connected systems. For example, a rotary position sensor may be mounted adjacent to the pedal to measure how far down the pedal is pressed. The harder the operator presses, the deeper the pedal is depressed, allowing more fuel and air to be delivered to the engine, so the vehicle moves faster. When the operator removes their foot from the pedal, the Hall effect rotary position sensor senses the change in position and sends a signal to the engine to reduce the flow of fuel and air across the throttle plate. The vehicle responds to this signal by slowing down. These sensors can also be used in buses and heavy-duty ride-height systems to sense the travel of the suspension system. Buses use 'kneeling' systems to lower their height so that passengers can board easily. The Hall effect rotary-position sensor can be used on both ends of this application: one position sensor monitors the position of the control lever, and a second position sensor is deployed on a suspension arm or a linkage to monitor ride height. Accurate position sensing validates that the vehicle is at the correct height for the application system's requirement, improving vehicle ingress/egress. Large trailer trucks may also use Hall effect rotary-position sensors to monitor trailer heights to improve warehouse docking efficiency. In addition, these sensors can be used to monitor tilt/trim position for speedboats. The sensor accurately reports the angle position of the propeller, which can help the operator avoid damage and maintain optimum performance. Another interesting application is for irrigation sprinkler systems used by large farms. The sensor can monitor the angle range at which the sprinklers are irrigating. Is the irrigation system watering the section of the field intended, or is the system watering 360°? This knowledge can help the farmer reduce water consumption and increase crop yield. The control of process valves is vital in a wide range of industrial applications. Oil fields, nuclear power plants, food processing plants and beverage manufacturers require that valves accurately monitor positions. Hall effect rotary-position sensors are used to monitor position in large and small valves to help ensure that the valve is closed or if it is open, how open. Heating, ventilation and air conditioning systems also use rotary position sensors for damper control. On a cold day, an open damper may feed cold air into a room, causing the HVAC system to engage heat. An open damper may feed air into a room that has open windows, reducing the system's efficiency and increasing heating and cooling costs. Effective use of Hall effect rotary-position sensors, in conjunction with temperature sensors, allows the building manager to better control the HVAC system and reduce operating costs.