Gearless elevator drive

Since the 90s of the last century in the world, and then in Russia, gearless elevator mechanisms have been increasingly used. The point is to refuse from the bulky gearbox and to move the elevator car only by rotation of the pulley, tightly seated on the motor shaft. Change of rotation speed is due to the use of a frequency converter, the accuracy of movement and stopping is ensured by encoder and various sensors.

In Russia, asynchronous motors are most often used as gearless winches. These are low-speed motors (60-200 rpm) with high torque (from 200 Nm). Frequency conversion system with position and speed feedback, as well as control of the cabin weight results in smooth running and precise stopping.

The widespread use of induction motors is due to their advantages over other types of electric motors: constructive simplicity and, as a consequence, high reliability and low cost.

Practice shows that they work reliably and are economically justified in elevators of large capacity (from 1500 kg) and in high-rise buildings. The disadvantages of their use include errors in the return of the control system to the state of equilibrium after the effect of feedback and stability of the motor control model at low speeds. This creates certain difficulties in setting up frequency converters and comfort of the elevator as a whole. Specialists try to solve this problem by improving the algorithm and mathematical model of motor control in frequency conversion.

Another direction in the development of electric drive is the use of permanent magnet synchronous motors (PMSM or in English abbreviation SMPM). These motors are capable of developing sufficient shaft torque at low speeds and even in stop mode.

Such motors have started to be produced outside the Russian Federation. Along with American and European motors, electric motors from China are actively promoted. The principle of operation of a synchronous motor is that the magnetic field of the rotor coils, created with the help of permanent magnets, is coupled with the vortex field of the stator windings, in contrast to AD, where the torque is transmitted to the squirrel-wheel type squirrel-cage rotor due to the fact that the vortex field of the stator windings is ahead of the rotor field, creating "slip".

In Russia the production of elevator winches with synchronous motors is established in the company "European Lifting Machines".

Elevator winch of LL type. The design is a fixed stator around which the rotor with permanent magnets and a solidly fixed to it CPS rotates. The rotor at the same time is a brake drum.

Dimensions of the winch LL 01001 with load capacity up to 1000 kg width 670 mm, height 748 mm, depth less than 400 mm. Elevator winches of this type are installed directly in the elevator shaft and do not require a separate room.

Institute "NIPTIEM", which is a part of electrotechnical concern "RUSELPROM" has developed and manufactures a family of winches KIAT-LPP using synchronous slow-speed motor of its own design.

A frequency converter manufactured by KEB is used for speed control. Load capacity of elevators produced by the Institute "NIPTIEM" is up to 1000 kg, speed of elevator car movement is up to 2 m/s.

Pros of geared elevator winches

  • Due to the use of affordable and easy to manufacture ADs and gearboxes such elevator systems are used in budget construction of buildings and structures.
  • Habitual operation, good maintainability. There are many factories in the territory of the Russian Federation supplying both individual parts and units for replacement
  • The operating staff is well trained, the presence of a machine room where the most important units and mechanisms are located makes maintenance and repair easy and convenient.

Minuses of geared elevator winches

  • During the operation of the motor, inrush currents lead to higher power consumption (up to 30 depending on the operating mode).
  • The efficiency is less than 70%, and in transient modes no more than 40-50%.
  • Noises and vibration during operation.
  • The gearbox is an "extra" part that can fail, requiring constant maintenance
  • Installation of a geared winch requires a separate machine room.

Pros of gearless winches

  • Elimination of the gearbox - reduction of the metal intensity of the entire system.
  • Smooth stroke control, accurate stops.
  • Low noise (no more than 60-55 dB - the sound of a soft conversation) and low vibration.
  • Energy consumption is lower than that of geared winches due to the use of frequency control and reduced inrush currents.
  • Dimensions allow elevator winches to be installed directly in elevator shafts.
  • High speed of the elevator car.
  • Durable and maintenance free.

Minuses gearless winches

  • More expensive than a geared elevator winch.
  • Low maintainability - the complexity of components means that in case of failure it is practically impossible to repair them, or repair is comparable to the purchase of new equipment.
  • When purchasing, the possibility of interfacing between the motor, sensors and control system must be considered.

Ordering features of gearless elevators.

Necessary оdecide on elevator purpose. Depending on what functions the elevator will carry - passenger, freight, hospital, automobile - will depend on all other parameters.

Manufacturer's Choice. Elevator is a complex and expensive equipment. When choosing you should pay attention to the experience (the period of existence of the company), the availability of permits (licenses, certificates). Find out about the warranty on the elevator and the availability of service for this particular elevator in your city or at least in the region. If the company-manufacturer (supplier) provides services of installation supervision, when experienced specialists, if not mount the equipment, all equipment will be mounted and debugged correctly in accordance with the instructions of the factory. The manufacturing plant may have a questionnaire for ordering its products, in which construction drawings are requested, mine plan, reaming of the mine walls with indication of the type of fastening of embedded elements, machine room plan with indication of the axes of the mine, cabin, etc.

Decide on a budget. Elevators of the same line and from the same manufacturer can differ in price depending on the equipment and additional features. It should be remembered that the purchase price of an elevator with an induction motor as a drive and frequency regulation is lower than that of an elevator with a drive from SDPM. The most budgetary variant is with a geared winch.

The selection and ordering of a gearless winch is best left to the professional who directly services the elevator. As with any system, replacing one part may involve changing the entire installation. Let's take a look at the surface features of ordering gearless (GR) drives.

Drive Location. Location can be in a separate room, can be in the elevator shaft and placed on top, bottom, side. If the elevator winch is fundamentally different, then there is a problem of redesigning the mountings of the entire suspension system, the direction of movement of ropes, cab, counterweight. There is no need to mention that the entire design will need documentation, its coordination and protection before the relevant supervisory authorities.

Selection of the elevator winch itself. The load capacity must be in accordance with the requirements for passenger flow, building height, etc., which will lead to the question of the dimensions of the elevator car. The speed set by the winch will depend on the lift height and the customer's wishes. The load capacity and speed will influence the choice of cables that will modify the rope driving pulley. There is a very extensive supply of elevator gearless winches (GWBs) on the market. Large elevator manufacturers develop and produce elevator winches for their needs and the needs of smaller elevator manufacturers. In Russia there are a number of factories producing gearless winches at the level of foreign ones.