Linear measurement system for safe shaft copying

Inspired by "everything under one roof", Kübler came up with the idea of marketing a new measurement system for safe, absolute shaft copying, together with its portfolio of encoders and bearingless encoders.

Kübler’s linear measurement system is mounted directly on the car. As a result, the absolute position is recorded permanently, which among other things is needed for the precise trip to the desired floor. The absolute position feedback makes a reference trip unnecessary in the event of a power failure, since absolute position values with a resolution of 1 mm are available at all times up to a total conveyance height of up to 392 m.

Virtually silent operation of the system

Another advantage of direct mounting is slip-free measurement. Measurement errors can occur during the permanent operation of a lift, triggered by vibrations or dynamic rope effects. This does not affect the linear measurement system, meaning that the absolute position of the car is guaranteed. The sensor housing, made of aluminium and V2A stainless steel strip ensure reliable deployment. The shaft copying system is based on contactless measurement and as a result is wear-free.

The Kübler shaft copying system is just 135 x 45 x 33 mm. The system can also be easily deployed even in the most cramped installation spaces in the event of retrofitting, modernisations in existing buildings / lift shafts or new installations. The extremely compact housing and robust stainless steel belt that runs around the housing contribute to the virtually silent operation of the system.

Easy installation

The system is supplied with an assembly kit, consisting of two attachment brackets, the rolled-up stainless steel belt and a spring element. The attachment brackets are mounted directly on the lift rail in the area of the shaft head and shaft pit. The sturdy stainless belt (V2A) is simply suspended from a spring hook included in the assembly set and attached in the shaft pit with a spring element and runs directly through the sensor housing.

Compared to other measuring systems, no other attachment elements or anything of the kind need to be added for the installation of the system. In addition, the stainless steel belt is very strong and can withstand scratching or bending during installation and is resistant to magnetized screwdrivers.

Conveyance heights up to 392 m

The measurement system is designed for conveyance heights up to 392 m and a resolution of 1 mm. Consequently, it can adjust to the requirements of the particular lift type and situation. Kübler provides three combinations with the relevant interfaces (SSI, CAN, CANopen, RS485, CANopen Lift) of the lift industry: Ants Base, Ants Safe, Ants Safe-System, sensor + evaluation unit) + UCM module.

The safe version (LES) includes a SIL3-certified measurement system and can in addition be combined in the third version with the matching SIL3-certified evaluation unit and UCM module. An excerpt of the possible safety functions: reference trip/ correction trip, inspection restriction above & below, shifting of the stop, over-speed during inspection, unintended car movement (UCM), inspection restriction for shortened shaft heads/shaft pits.

Ready for EN 81-20 and EN 81-50

Lifts are able to meet the requirements of the standards more easily with the shaft copying system in the corresponding safe versions. Consequently, numerous safety and lift functions can be implemented in a safe, uncomplicated manner. For example, these are limit switches at the top and bottom, early door opening / repetition and unintentional car movement (UCM).

Based on an internal plausibility check, the safe version always communicates the right position of the car. If an error occurs in the overall system, the lift is put into a safe operating condition by triggering of the respective safety function.

The linear Kübler shaft copying system makes many components superfluous in the lift shaft. If one bears in mind that in order to record the absolute position in conventional lift systems using several solenoids is necessary, this not only means many hours of installation, but also an enormous maintenance effort and a complicated search in the event of errors.

Sascha Moosmann
The author is the product manager for linear measurement technology at Kübler.

www.kuebler.com