Precise positioning and speed control of elevator cars is essential for optimum driving course. With encoders for position and speed detection can be driven any distance / time curves. While for the 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 is exhibiting its extensive Interlift encoder program for the industry.
Important features of sensors for elevator are. Besides reliability, safety and cost, simple installation and operation, as well as convenient connectivity to the master controller
Wide variety of interfaces
In the specially designed to meet the needs of the digital shaft encoders all have been incorporated, the Baumer has collected in this area in the last two decades. Reliability, ease of installation options and a great variety in the interfaces are the result. The optical or magnetic incremental and absolute encoders for position and speed sensing the elevator car today cover practically all conceivable tasks in elevator. The encoders that exist with different shaft and hollow shaft diameters, can be mounted are good, solid, reliable and very communicative: Besides the classic SSI interface is the connection of all common fieldbus and Ethernet interfaces possible and the CANopen Lift Protocol is supported. The sensor specialist has from the outset introduced his expertise here and long encoder in the program to support this specifically geared towards the needs of the elevator construction protocol. One example is the compact Multi-turn absolute encodersWho works on the patented gearless "Touchless encoder principle" and therefore wear-free. It is suitable for ambient temperatures from-20 80 ° to + ° C. The values for the shock resistance will be 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 field of elevator technology for control tasks often need two encoder types can be combined: When operating the speed control of the car drive, the signals of an incremental evaluation. The precise control of the stories, however, requires the absolute position signals of a multi-turn encoder. With multi-turn rotary encoders that provide two additional to 90 level-shifted signals, the user can now kill two "flying" with one stone: The integrated ASIC both the absolute and the incremental signals and provides them via standardized interfaces of the control processes for speed and position control is available. In addition to the speed monitoring can bring to the incremental signals of the rotary encoder 90 degree also use for other purposes, for example, for the slip or differential monitoring of the drive belt or steel cables.
Velocity measurement at the drive belt
Velocities and positions can be measured in lifts directly on the drive belt. The Wheel encoder MA20 this provides a very viable solution. For this purpose a high-resolution optical incremental encoders has been combined with an accurate measuring wheel and a spring-loaded bracket (picture 3). The encoder supplies with patented Low Harmonics technology 25.000 pulses per revolution, allowing even in slow motion high accuracy. 16 resolutions between 100 and 25.000 pulses are predefined and selectable via a HEX switch. The continuously variable pressure of the measuring wheel with differing application also provides ideal conditions for liability without slippage. Thanks to the rotating, swivel and height-adjustable mounting arm can be mounted to the wheel encoders quickly and easily.
Space-saving mounting directly on the drive
Magnetic encoders without integral bearing are suitable due to their rugged design is also good for the lift industry. As the first manufacturer Baumer bearingless rotary magnetic encoders now also offers a very compact design, so that points to the advantages of non-contact measuring principle also use in very tight spaces. The small absolute encoder with the type designation MHAD that complements the proven MAG HD encoder family needs, with a diameter of 50 mm and a depth of only 20 mm very little installation space and fits virtually into any space. For the assembly, no free shaft end is necessary. Thanks to its large through hollow shaft encoder, for example, can be the space-and cost-saving directly onto the shaft between the gearbox and anzutreibendem machine part. At the output of the encoder is the current position as an absolute value with 16 bit resolution, either via SSI or CANopen interface. For speed control additional incremental output (1024 to 8192 pulses per revolution). Since the compact design can be arranged up to four sensors at the flywheel, redundant solutions are easily and inexpensively. The self-diagnosis monitors signal quality and constantly checks the sensor function.
Reliability through redundancy
As a pioneer in safety-compliant encoders Baumer has expanded its program continuously, so that today virtually all lift can solve specific problems with redundant encoders. A good choice would, in many cases, for example, the safety-conscious, optical multi-turn absolute encoder with two redundant interfaces (SIL 3 approval or PLe). He has already proven itself in practice. Versatile, rugged and reliable are the Incremental and sine encoders with SIL2 or PLd classification.
Special solutions for the lifting technology
Are the environmental conditions particularly rough, recommend designs that work exclusively with magnetic scanning. The encoder family "Magres redundant" provides a good example. Despite the redundant design of single-and multi-turn encoders are part of the compact. If necessary, they can be combined with an equally compact cable. Such Cable-pull suitable for numerous vertical conveyors, such as lift tables and widely used in automotive Scissor-type lifting. Versatile, rugged and reliable are the Incremental and sine encoders with SIL2 or PLd classification. Some typical applications for this level of security not only in the elevator, but in the entire drive technology for mechanical engineering, where it is important to monitor procedures to protect people and assets.
Diagnostic system for fault monitoring
The encoders are designed to work reliably even under adverse conditions and in fact already been proven in countless applications. Since often the trust itself on reliable technology alone is not enough, offer themselves just for elevator shaft encoder with integrated control function. This so-called "Enhanced Monitoring System "(EMS) based on a fast microprocessor continuously monitors all encoder functions over the entire speed range. Possible failure can thus be determined quickly and easily. An alarm output signals of the control an observed malfunction. The operating states are also displayed directly on the encoder with an LED.
The author Heinrich Greiner Head of Marketing Communication, Product Segment Motion Control, Baumer Group.
Interlift 2011, 5 Hall, Booth 5085