Sensors, small electrical motors and harnesses are increasingly important and crucial for the optimal operation of modern motor vehicles. The perfect definition of these components represents an unquestionable factor of competitive advantage for today’s motor vehicle manufacturers, allowing them to reach high levels of driveability and travel comfort, fuel consumption efficiency, reduced pollutants and greater control reliability and accuracy of modern powertrains.
Sensors and small motors are active parts needed for proper definition of blends, air control, and verification of the positions and of all physical parameters used to provide the necessary feedback to the engine and transmission control units, allowing them to carry out the necessary controls, while the harnesses make it possible for the control units, sensors and “actuators” to work well together, exchanging information while preventing any external phenomena from compromising the operation of the whole.
In a modern Powertrain system, inside the throttle bodies and in the actuators for swirl and/or tumble devices, sensors determine the opening angle of the throttles, while the electric motors accurately open and close them based on the needs and on the desired speed. In fuel rails and in air intake manifolds, sensors measure the pressure and temperature of the fluids. In the engine exhaust, sensors are used to measure the air/fuel percentage, while on the engine they measure rotation speed, vibrations, noise level, temperatures of cooling fluids and lubricants, etc.
Magneti Marelli Powertrain is at the vanguard in this area too, and it is leader in Europe in the extensive use of contactless angular and linear measuring devices in the automotive sector, constantly committed to identifying and developing innovative solutions that maximize measuring quality and functionality at the lowest possible cost.
Specifically, one of the most innovative developments, which can be potentially applied to all engine systems, is the “Fast Synchronization Sensor” (FSS), intended to replace with a single electronic device what today is the set of an inductive sensor and what is known as the “phonic wheel” of an engine.
FSS - Fast Sync Sensor
The current solutions used in the automotive sector for the detection/reading of the number of drive shaft revolutions have required for some time the use of a phonic wheel, equipped with a sensor that is currently the Hall-effect type with single/double cell.
Despite the technological advancements of the aforementioned sensor and the implementation of additional functions (e.g. detection of the direction of rotation), the limit of the current solutions, in terms of reading accuracy of the number of drive shaft revolutions, consists in the construction/realization accuracy of the phonic wheel mechanical component.
The Magneti Marelli solution aims at overcoming such limit by replacing the conventional phonic wheel with a magnetic dipole, keyed to the end of the vehicle drive shaft by means of a non-magnetic magnet holder, in front of which a magnetic encoder sensor is positioned.
The benefits of such solution can be summarized as follows:
· Reduced weight/overall dimensions through the elimination of the phonic wheel
· Greater accuracy of the engine revolutions measurement system no longer limited by the geometry/mechanical accuracy of the phonic wheel
· Programmable resolution of the engine revolutions sensor depending on specific application requirements
· Detection of drive shaft absolute position at the vehicle key-on and for low speeds
The theoretical/experimental activity carried out so far by Magneti Marelli has confirmed the benefits listed above.