The new intelligent sensor is ideal for a range of mobile machinery including construction equipment or municipal vehicles.

Instrotech, local distributor of process control instrumentation and specialised systems, has launched SIKO’s new SGH10, a measuring system for direct stroke measurement in hydraulic cylinders. The specialised measurement solution is said to be “based on customer feedback and many years of experience in path measurement technology”. The cylinder stroke is measured precisely using Bowden cable sensor technology installed directly in the cylinder.

The new intelligent sensor is ideal for a range of mobile machinery including construction equipment or municipal vehicles. Accurately recording paths and angles is an integral component of intelligent operating concepts and functions. These functions are said to improve not only the convenience, but also the safety of mobile machines. Using intelligent sensors also increases the performance and efficiency of mobile machines, allowing repetitive work processes to be automated and therefore relieving machine operators at the same time.

Since most motion sequences for mobile machines employ hydraulic cylinders, one of the most important measurement tasks for sensor technology is precisely determining the stroke of the cylinder to enable measurement and monitoring of the motions to be carried out.

The SGH10 cylinder stroke measuring system is said to pursue an entirely different technological approach than measuring systems commonly found in the market, which are based on magneto-restrictive, inductive, or hall based technology. In contrast to these systems, a Bowden cable mechanism installed directly in the cylinder is used to measure the stroke.

The cable of the Bowden cable mechanism is mounted in the piston head. If the cylinder is extended, the cable, which is wound up in a cable drum, is pulled out. The rotation of the cable drum that is thereby created is detected without contact by the sensor electronics and used to calculate the linear travel. This makes it possible to detect the position of the cylinder precisely and completely at all times. The magnets that are used to detect the rotation are scanned by the electronics through the pressure-resistant base plate of the SGH10.

Electronics

The electronics are fully encapsulated on the unpressurised side of the system. This means the entire measuring system is built into the cylinder and is optimally protected from external environmental conditions. This provides a clear advantage: in contrast to a measuring system mounted externally on the cylinder, the sensor system cannot be influenced or damaged by loose parts or by environmental influences.

Another revolutionary aspect of this new system is the reduction of costs for integrating the system into the cylinder. This is because in previous measuring systems, the sensor rods had to be integrated into the piston over the entire measuring path; this often required long and highly precise bore holes in the piston. This is not only expensive, but also weakens the structure of the piston. In the SGH10 stroke measuring system, just one small thread is needed in the piston to mount the cable. This allows the system to offer major potential cost savings, which affects production times and, ultimately, overall costs for hydraulic cylinders. The greater the stroke length, the greater the potential for monetary savings, the company says. Cylinder manufacturers, mechanical engineers and end-use customers reap the benefits.