Incremental and absolute rotary encoders for elevator construction

Details: Released: 28.08.2011; Last updated: 07.02.2024; Hits: 24741

An exact positioning and speed control of Elevator cars is a prerequisite for optimal driving. With encoders Any distance / time curves can be used for position and speed detection. While up for speed detection Incremental offer, you realize with the positioning Absolute encoders. The position values will not be lost even after a power failure and referencing are unnecessary. Baumer offers an extensive range of encoders for the Elevators.

Contents

Large variety of interfaces for incremental and absolute value encoders
Multiturn encoder with additional incremental
Velocity measurement at the drive belt
Space-saving mounting directly on the drive
Elevator safety through redundancy
Solutions for lifting technology
Diagnostic system for fault monitoring

Important features of sensors for the Elevators In addition to reliability, safety and economy, they are also easy to assemble and use, as well as convenient connection options to the higher-level controller.

Large variety of interfaces for incremental and absolute value encoders

In the specifically on the concerns of the digital Shaft copying designed rotary encoders have incorporated all the experience Baumer has gained in this field over the past two decades. Reliability, easy installation options and a wide variety of interfaces are the result.

The optical or magnetic incremental and absolute rotary encoders for position and speed detection of the elevator car now cover practically all conceivable tasks in elevator construction.

The rotary encoder designs, which are available with different shaft diameters and a hollow shaft instead of a solid shaft, are easy to install, are robust, reliable and very easy to communicate: In addition to the classic SSI interface, the connection is via all common ones fieldbus- and Ethernetinterfaces are possible and the CANopen Lift protocol is also supported.

The sensor specialist has brought its know-how here from the start and has long had encoders in its range that support this protocol, which is specially tailored to the needs of elevator construction.

An example of this is the compact multiturn absolute encoder, which works without gears based on the patented “touchless encoder principle” and is therefore wear-free. It is suitable for ambient temperatures of -20 ° to +80 ° C. The values for shock resistance are 2000 m / s². The encoder achieves a resolution of 29 bit wherein 13 bits are used for the angular information and 16 bit for the number of revolutions.

Multiturn encoder with additional incremental

In the area of elevator technology, Regulatory tasks Often two encoder types are combined with each other: During travel operation, the signals from an incremental encoder are evaluated for the speed control of the car drive. The precise control of the floors, on the other hand, requires the absolute position signals of a multiturn rotary encoder.

With multiturn encoders that deliver two additional incremental signals offset by 90 degrees, the user can now Killing two birds with one stone: The integrated ASIC processes both the absolute and the incremental signals and provides them via standardized interfaces of the steering available for speed and position control. In addition to speed monitoring, the incremental signals of the rotary encoder, which are offset by 90 degrees, can also be used for other purposes, for example for slip or differential monitoring of the drive belts or steel cables.

Velocity measurement at the drive belt

You can also set speeds and positions for elevators Measure directly on the drive belt. The MA20 measuring wheel encoder offers a very practical solution for this. A high-resolution optical incremental rotary encoder was combined with a precise measuring wheel and a spring-loaded mounting arm (Fig. 3). Thanks to the patented Low Harmonics technology, the rotary encoder delivers 25.000 pulses per revolution, which enables high measurement accuracy even with slow movements.

16 resolutions between 100 and 25.000 pulses are predefined and selectable via a HEX switch. The infinitely variable contact pressure of the measuring wheel ensures ideal adhesion without slippage even in the case of differing application conditions. Thanks to the rotating, swiveling and height-adjustable mounting arm, the measuring wheel encoder can be installed quickly and easily.

Space-saving mounting directly on the drive

Magnetic rotary encoders without their own bearings are also well suited for elevator construction because of their robust design. Baumer is the first manufacturer to offer magnetic rotary encoders without bearings now also available in a particularly compact design, so that the advantages of the non-contact measuring principle can also be used in very confined spaces.

The small Absolute rotary encoder MHAD, which complements the tried and tested HD MAG encoder family, with a diameter of 50 mm and an installation depth of only 20 mm requires very little installation space and fits into practically any gap. No free shaft end is required for assembly.

Whisper-quiet elevator brake secures elevators and escalators

Thanks to its great Through hollow shaft For example, you can place the encoder directly on the shaft to save space and costs Transmission and mount the machine part to be driven. At the output, the encoder provides the current position as an absolute value with 16 bit resolution, either via SSI or CANopen interface. An incremental signal (1024 to 8192 lines per revolution) is also output for speed control. Since the compact design allows up to four sensors to be arranged around the magnet wheel, redundant solutions can be implemented easily and cost-effectively. The integrated self-diagnosis monitors the signal quality and constantly checks the sensor function when measuring the speed.

Elevator safety through redundancy

As a pioneer in the field of safety-relevant encoders, Baumer has continuously expanded its range so that today practically all lift-specific tasks can be solved with redundant encoders.

In many cases, a good choice should be, for example, the safe, optical multiturn absolute encoders with two redundant interfaces (SIL 3 approval or PLe). It has already proven itself in practical use. The incremental and sinusoidal encoders with SIL2 or PLd classification are also versatile, robust and reliable.

Solutions for lifting technology

If the ambient conditions are particularly harsh, designs that work exclusively with magnetic scanning are recommended. The encoder family Magres redundant provides a good example of this. Despite the redundant structure of the single and multi-turn part, the encoders are very compact. If necessary, they can be combined with an equally compact cable pull.

Such Cable-pull are suitable for a large number of vertical conveyors, such as those in Automotive engineering widely used lifting tables and scissor lifts. The incremental and sine encoders with SIL2 or PLd classification are also versatile, robust and reliable.

typical Applications This level of safety exists not only in elevator construction, but in the entire drive technology for mechanical and plant engineering, where it is important to monitor processes in order to protect people and systems.

Diagnostic system for fault monitoring

The encoder are designed to function reliably even under the most adverse conditions and have already proven this in countless applications. Since trust in even the most reliable technology is often not enough, encoders with integrated function control are particularly suitable for elevator construction.

This so called enhanced monitoring system (EMS) is based on a fast microprocessor that continuously monitors all encoder functions over the entire speed range. Any malfunctions can thus be identified quickly and easily. An alarm output reports a detected malfunction to the control. The operating states are also displayed directly on the encoder via an LED.