A multi-sensor for condition monitoring of hydraulic oils

More and more auxiliary aggregates and functions implemented in the range of mobile machinery and particularly of agricultural machinery are using hydraulic technology. The oil changes are normally required after a certain number of operating hours which is adapted according to experience and a specific safety factor to ensure a trouble-free operating of the machine. Thus the oil is often in a good condition when the change takes place. To improve this disadvantage and for a complete condition monitoring of the oil a multi-sensor was developed which measures the characteristic values resonant frequency (viscosity), electric permittivity and electric conductivity. Test in the laboratory and in hydraulic systems showed good results. The combination of these parameters makes a statement on the oil condition possible. The economic effiency of the sensor will be reached in most cases; particularly the increasing availability is a great advantage for the owner of the machines.