Classic hydraulic cylinders equipped with force-sensing elements allow precise and dynamic measurement of static and dynamic tensile and compressive loads. Indirect force-measurement via strain offers a smart alternative, according to engineers at Liebherr Components, Nussbaumen, Switzerland.
Increasingly, mobile and industrial equipment manufacturers are focusing on sensor solutions and their efficient use in hydraulic cylinders. One driver, for example, is force-measurement within the cylinder. It is always advantageous when an application demands precise and dynamic values of the prevailing forces — for example when monitoring loads in excavators and cranes. In this way, dangerous situations during crane operation can be avoided and the efficiency of the machine can be improved.
Typically, force in the cylinder is determined indirectly via the oil pressure. These measured values are prone to error due to internal friction and other factors. This is why Liebherr relies on direct force-measurement via strain with a force-measurement sensor.
The internal measuring points track both static and dynamic tensile and compressive forces regardless of lateral forces and torques. “The measuring method ensures significantly more precise and dynamic measurement results,” said Hans-Peter Laverne, Head of Advanced Development at Liebherr-Components. “This establishes the conditions for higher productivity and safety in daily use in various applications.”
Currently, Liebherr’s cylinder force-measurement system is a functioning sensor prototype. It stands out in particular due to its suitability for highly diverse types of applications. During the design phase, Liebherr’s development team can account for individual adaptations and, therefore, offer customized solutions.
The improved force-measurement brings further advantages, said company officials. These include, for example, an increased performance in operator-assistance systems through optimized sensitivity. Thanks to highly dynamic and precise measurement, longer service life expected. And engineers predict this type of new sensor package will offer higher efficiency and safety during daily use, as well as digital condition monitoring of hydraulic cylinders for automation solutions. It should also permit system downsizing.