The intelligent position
The intelligent position transducer for hydraulic cylinders The new intelligent position transducer ‘LiView’ from the equipment manufacturer Liebherr, determines the exact position of the piston and the speed through its high-resolution absolute measurement mechanism. The Liebherr ‘Liview’ positiontransducer, perfectly suitable for automation of mobile machinery DRIVE TECHNOLOGY WORLD OF INDUSTRIES – MOTION, DRIVE & AUTOMATION 3/2017
The unique measuring concept of LiView Modern measurement systems in mobile machinery face specific challenges, like severe heat up to 85 °C, fierce vibrations or aggressive salt water. Based on the extensive know-how of extremely demanding operating conditions, the heavy equipment manufacturer, Liebherr has developed a new position transducer ‘LiView’. With its completely new measurement mechanism, it can be easily integrated, is extremely robust and is universally applicable, especially for automation of mobile and heavy machinery. Unique measuring concept ‘LiView’ utilizes the piston itself as robust sensing element. The system consists of the processing electronics and two probes. ‘LiView’ measures the cylinder’s scattering parameters using signals at different frequencies injected onto the cylinder itself. Piston position and speed are calculated in real-time by the processing electronics. This allows dynamic automation of machines for more efficiency and higher productivity. Measurement process in detail: 1) The electronic unit generates a signal 2) This signal is then coupled into the cylinder via a probe (Port 1). 3) The signal then advances towards the piston and is reflected back 4) The reflected signal returns to the electronic unit via a second probe (Port 2). About the Liebherr Group Hans Liebherr established the company that bears his name in 1949. Since then it has grown into a Group of more than 130 companies on all continents, employing 42,308 people at the latest count. Today, Liebherr is not only among the world’s largest manufacturers of construction machinery, but is an acknowledged supplier of technically advanced, user-oriented products and services in many other fields of activity as well. Besides earthmoving and mining machinery, the portfolio comprises mobile, maritime and tower cranes, concrete technology, aerospace and transportation systems, machine tools and automation systems as well as domestic appliances and components. In 2016, the family-owned company generated an annual turnover of more than 9 billion Euros. 5) The electronic unit then calculates the position and speed of the piston in real time. This new measuring concept ensures a fixed installation of all components. No moving parts in oil (e.g. magnet), which may cause an oil contamination including a machine breakdown, are required. Easy to integrate, easy to maintain LiView convinces through fast and easy mechanical integration. The electronics can be installed either on the cylinder or directly on the machine. Only both probe heads require a connection to the piston rod bearing. The probe heads swim on an oil film and are therefore wear-free. No further modifications of the cylinder or drilling the piston rod are necessary. The integration concept of the system ensures easy accessibility of all components. In case of an external damage, this allows fast and simple maintenance – without draining oil, dismantling or even disassembling of the cylinder. When using LiView, the space in the cylinder can be used entirely for the idle stroke, as the probe heads are integrated in the piston rod bearing. Therefore, the full cylinder length is available with the position transducer installed. LiView supports the standardised protocols CANopen and CANopen Safety. Thus, it can also be easily integrated in the control system. An intelligent and customized solution for cylinder movements The LiView concept allows installation on the smallest as well as in very long cylinders. Thus, the system is generally suitable for all cylinder lengths and piston diameters. It’s functionality can be configured in accordance with the specific application requirements. This ensures high efficiency, when using the system. For safety-relevant applications, LiView is certified according to EN ISO 13849 PL d and EN IEC 61508 SIL2. This intelligent position transducer from Liebherr, calculates piston speed in real time with a measurement cycle of
