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Drive controller

The invisible lift car door opener

Published 2018-01-31

The Swiss elevator manufacturer, Schindler, and Maxon Motor also located in Switzerland have developed jointly a CAN-connectable drive system that moves the car lift doors.

Schindler moves over one billion people per day in its elevators (Photo: Schindler)

“Elevators are among the things in our daily lives that we take for granted. We press the button, the cab arrives, we enter and are taken to the desired floor quickly, safely, and reliably. Yet hidden from the passengers’ eyes, there is a lot of technology involved in the elevator shaft, in the motor chamber, in the control box, and in the cab itself,” explained Stefan Roschi from Maxon. “A motor installed in the cab is responsible for opening and closing not only the door of the cabin, but also the door to the respective floor. The demands on this motor are high: It has to be small yet powerful, energy-saving, reliable, and, most importantly, intelligent.”

The door drive controller is available in two power levels. The more powerful version uses a belt drive and is able to move doors of up to 400 kg. The smaller version is a direct drive. This saves space and is suitable for doors up to 120 kg. The drive system comprises a brushless, 90-mm diameter DC motor and a MILE encoder integrated directly on the printed-circuit board. It is combined with a customer-specific positioning controller based on the EPOS2 series. The provided CAN interface uses some features of CANopen, but does not comply with CiA 301 (application layer) or CiA 417 (application profile for lift).

The joint developed drive system is based on Maxon’s EPOS2 controller featuring CAN connectivity (Photo: Maxon Motor)

Encased in a housing, the door drive controller can be mounted directly to the lift cabin. “This is where its real work starts,” explained Roschi. “There are many different types of elevators, with differently sized cabs, different materials and, depending on the country, different safety standards. After a calibration procedure, the controller of the Door Drive detects the size and weight of the doors, autonomously calculates the optimal parameters, and corrects them if necessary. This greatly simplifies the elevator technician’s work. In just a few steps, the Door Drive configuration is complete, and the drive is ready for use.” He added: “The advantage of the flat motor’s narrow design is that the cab can be made bigger. The drive also saves energy and it delivers sufficient torque to smoothly move the doors. The integrated controller is intelligent and with continuous operation, it collects valuable data that the technicians can access at any time. This means that besides doing its main job, the drive also functions as an assistant behind the scenes.”