Optical Sensor for the Needle Lift Detection in the Common Rail Injector
The displacement of the control piston within a Common Rail injector is a key area that requires more focus to suitably characterise the behavior of an injector, it is a key element to discuss when investigating in-nozzle phenomena, the needle displacement is typically measured with a eddy current sensor. Apart from its high cost, scientific literature highlights its drawbacks, such as the introduction of mechanical weakness on the control piston as well as an electromagnetic disturbance affecting the data acquisition. Other solutions have been developed which provide an improved quality of signal. Nonetheless, such solutions require a high number of components which leads to an increased layout complexity. This layout can create a packing issue when trying to mount the sensor on the test rig. A novel sensor (UK Patent Application No.1819731.9) has been designed and built to overcome the limitations typically associated to the needle displacement transducers.