Lift hydraulics: power and elegance, coupled with intelligence

Hydraulic drive technology for lift construction comes into play if great forces or architecturally demanding solutions are called for. Bucher Hydraulics has now gone a step further: lift technology has become smart and networked.

By Tony Aschwanden

Goods lifts with high loads are the domains of hydraulic lifts. They can raise loads of 40 tons and more 25 m and higher. The advantage: the forces can be dissipated directly via the building foundation. But hydraulics can also be elegantly deployed. Architects appreciate hydraulic lifts with lots of glass and slender cylinders instead of intrusive ropes. This is now even feasible completely without lateral guide rails for the car.

About five million lifts in the EU consume 18 terawatts in electricity annually, about 0.7 percent of all electricity needs. This is why, in my view, they should be subject to the EU Ecodesign Regulation. However, hydraulic lifts are energetically already on the right course and often superior to rope lifts when considered over their entire life cycle.

Frequency converters, with which the pump output can be adjusted exactly to the travel curve, from speed zero on, play an important role here. The additional costs amortise themselves in busy lifts in view of the 30 to 40 percent energy saving.

Another 20 to 30 percent in energy can be saved by supercapacitors, so-called supercaps, which can be charged and discharged faster than batteries. Oil flowing back drives the pump, which turns the motor that serves as generator. The supercaps save energy via the frequency converter in order to provide it during the next trip upwards. The technology can also be retrofitted with corresponding software modifications.

"A new era of lift hydraulics"

Photo: © Bucher Hydraulics

The intelligent hydraulic valve iValve is an optimisation of the LRV (lift control valve) in the direction of Industry 4.0. Its installation and start-up only take 60 minutes instead of 200 minutes in the case of a conventional valve and 120 minutes for an LRV. All that is needed are two connection lines between electronics and valve.

Thanks to sensors and corresponding software, it is self-learning and self-optimising. The elimination of the basic setting of the valve and optimisation of the travel curve by means of íTeach, based on the shaft information supplied by the lift controller, contribute most to the time saving.

This is what an initial travel curve after mounting looks like: moving off with long start phase and creep speed, full speed, deceleration and once again long creep speed phase until the valve stops. About 14.5 seconds pass between the start and stop of this trip. Within the first five trips, the iValve optimises via iTeach and in this way reduces the total travel time to 8.5 seconds, thus saving a great deal of energy. Sensitive regulation via a closed control circuit ensures good travel properties and great stopping precision in both directions - irrespective of oil temperature and viscosity.

Easy networking with CANopen Lift

Photo: © Bucher Hydraulics

In combination with the iCON electronics, the iValve offers all the options of modern networking technology. CANopen Lift, an open source quasi standard in lift technology, serves as bus system. This simplifies the wiring effort with the lift overall and communication with the drive.

Thanks to the optional CANopen connection via an expansion card on the iCon controller, no additional terminals are needed. The parameters can be changed centrally via the lift controller. The iCON controller is fitted with error memory, which can be read for on-site analysis or even remotely via smart devices.

For the lift builder, this means the direct path to predictive maintenance: the iValve can provide data log files or warnings, which can be forwarded to the lift controller and from there globally.

The author is Head of Product & Application Elevator and Electrohydraulic Systems at Bucher Hydraulics.

More information: bucherhydraulics.com/aufzug