LiView: Measuring the Precise Position of Hydraulic Cylinders

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Liebherr is presenting the new “LiView” system at the 2013 Bauma. It is an innovative electro-hydraulic system for precise, reliable measuring of the position taken up by hydraulic cylinders in any size category, to an accuracy as high as +/- 1 mm. Its strong construction makes LiView especially suitable for use on construction machinery and mining equipment. With the position data supplied by LiView, construction machinery movement sequences can be automated and their performance and ease of control greatly enhanced. LiView, a joint development by Liebherr-Hydraulikbagger GmbH in Kirchdorf and Liebherr-Elektronik GmbH in Lindau, demonstrates Liebherr’s system competence and its lengthy experience in the fields of hydraulics and electronics.

The hydraulic cylinder as a capacitor

The LiView system is based on the idea of treating the hydraulic cylinder as an electronic component, namely a capacitor. An electronic control circuit measures the capacitance of the hydraulic cylinder. This varies according to the degree of extension. To obtain this information, all that is needed are cables attached to the piston rod and the cylinder barrel. Effectively no changes have to be made to the well-proven cylinder geometry. This reduces costs and ensures a very low error rate. In addition, the system  can be adapted to suit clients’ individual requirements. The measured data is transmitted to the machine’s control system via standard interfaces.

Exceptionally strong construction

Thanks to the straightforward concept outlined above, the LiView system is suitable for tough working conditions on earthmoving machinery and mining equipment, where the loads that have to be handled often give rise to severe vibration and shock. LiView can be used on even the largest Liebherr mining-equipment cylinders, which can be up to 5 metres long. There is in fact no limit to the size of the hydraulic cylinders to which this system can be applied.

Paving the way for fully-automated machines

Precise, reliable measuring of the positions reached by all power hydraulics is a major step toward construction machinery capable of performing automated movement sequences. These positions are often determined by the extension and retraction of hydraulic cylinders. This is where the LiView system plays its part: the position of the piston rod is continuously measured by electronic means. The cylinder can therefore be actuated by the machine control system until it has taken up a predetermined position. By automating hydraulic cylinders in this way, the machine’s various positions and operating speeds can, as with a linear axis, be controlled more easily and safely than in manual operation.

Intelligent speed control and precise work sequences

LiView enables movement sequences to be reproduced; this speeds up work cycles and makes them more uniform. It is also possible to restrict speed in critical work areas and thus prevent uncontrolled machine movements.

The speed control integrated into the LiView system monitors the damping action of hydraulic cylinders electronically. This makes it possible to dispense with mechanical components such as damping sleeves.

Cost-effective and easy to maintain

Since the LiView system monitors the function of the hydraulic cylinder continuously, contamination or damage to components can be identified at an early stage. This results in longer periods of reliable operation and lower operating costs. The LiView system’s electronics are accessible from the outside, which greatly simplifies maintenance work.

Further information:

Simone Stier

Telephone:          +41 56 296 43 27

Fax:                      +41 56 296 43 01

E-mail:                 Simone.Stier@Liebherr.com

Internet:               www.Liebherr.com