What is the purpose of a variable reluctance sensor?
A variable reluctance sensor (commonly called a VR sensor) is a transducer that measures changes in magnetic reluctance. When combined with basic electronic circuitry, the sensor detects the change in presence or proximity of ferrous objects. With more complex circuitry and the addition…
How is torque measured with a VR sensor?
By attaching two reluctor rings to a shaft, the torque can be measured. The tooth spacing on reluctor rings may be uniform, or uneven. Although VR sensors are based on very mature technology, they still offer several significant advantages.
How is the output of a VR sensor readable?
VR sensor interface circuits VR sensors need waveform shaping for their output to be digitally readable. The normal output of a VR sensor is an analog signal, shaped much like a sine wave. The frequency and amplitude of the analog signal is proportional to the target’s velocity.
Which is more expensive a Hall effect or zero rpm sensor?
An alternative but more expensive technology is Hall effect sensor. Hall effect sensors are true zero-rpm sensors and actively supply information even when there’s no transmission motion at all. One area in which VR sensors excel, however, is in high-temperature applications.
What kind of sensor is a reluctor sensor?
A Reluctor sensor is typically a 2 wire sensor and does not have any fancy electronics. A Reluctor is made up of a permanent magnet, a ferromagnetic pole piece and coil of wire. Each end of the coil of wire is refered to as the Reluctor +ve and Reluctor -ve which are the signals that are fed into the ECU.
Which is more sensitive Hall effect or reluctor sensor?
The Reluctor sensors are much more sensitive to the Air Gap between the sensor and the trigger material. Getting that gap right is critical, it must be exactly the same between teeth and it is a much tighter gap than in Hall effect sensors, down around 10 thou or 0.25mm or even less in some cases.
How is the reluctor related to the Hall effect?
Instead of producing an easy to interpret digital square wave like a Hall effect sensor, the Reluctor sensors output magnitude is proportional to the trigger target speed. Basically, the faster the trigger tooth comes past, the higher the signal voltage the Reluctor sensor will generate.
What kind of sensor does the ECU use?
This is then evaluated by the ECU to determine how fast the engine is spinning (rpm) and where in the cycle the engine is. There are generally two different types of sensors used for crank and camshaft positions: variable reluctance and Hall.