What Is an Elevator Encoder?

Encoders installed on the main motor, brakes, shaft copying system and elevator doors help modern cable-bound elevators start gently, stop at just the right height, rapidly open and close their doors, and smoothly speed off again.

Encoders can also provide useful data to monitor operational status. For example, the KCI 419 Dplus offers comprehensive temperature monitoring and online self-diagnostic capabilities.

Positioning

The elevator encoder’s position is a crucial factor in determining how the elevator car will travel from floor to floor. It’s also used to provide motion feedback for automated assembly lines, robotic welding arms and many other applications that need a high-resolution measurement of a machine’s position.

Elevator drives that use synchronous motors require absolute angular position data of the rotor to achieve maximum torque. An encoder attached to the rotor provides this information to the variable-frequency drive (VFD) in the elevator system, which then controls the motor to move the elevator car up or down floors.

In addition, elevator door motors need feedback to open and close the doors in the elevator car. Encoders mounted on these motors are hollow-bore designs and compact enough to fit into the space available.

Because the door movement can be slow at the extremes of opening and closing, these feedback devices need to be high resolution. They also need to be able to withstand the high forces associated with door motors, such as vibrations, shocks and impacts from people or heavy objects.

HEIDENHAIN offers a wide range of encoders that meet all these requirements, including the HS35R, which can withstand a 400g shock. It also has larger bearings that help extend the life of the encoder.

As a result, it’s important to ensure that the motor shaft is clear of dirt and debris that could affect the mounting and positioning of the encoder. Additionally, ensure that all set screws are tight and that the encoder is squarely mounted on the motor shaft.

The HEIDENHAIN AFM60 absolute inductive encoder, for example, is designed to measure the rotor position of a synchronous motor to control its speed and position using two track measuring standards with different signal periods. This allows for accurate and dynamic position measurements.

Absolute encoders typically feature incremental speed channels consisting of sine and cosine waves with amplitude of 1Vpp, phase shifted by 90deg for the A and B channels. Depending on the A-B phasing of the encoder and the manufacturer’s established convention for position incrementing and decrementing, channel A may lead or lag channel B.

Speed

Encoders allow elevator control systems to accurately determine the motion of the elevator while also providing feedback information that is transmitted back to a computer. This enables the elevator to stop level with the floor, open and close the doors, and provide a smooth and comfortable ride for passengers.

Encoder speed is a critical aspect of elevator operation. If the encoder is not able to send its feedback signal, the motor can move in unintended ways, which may lead to injuries or other problems.

In order to avoid this problem, elevator designers should consider a few things. First, they should ensure that the encoder’s supply voltage is properly configured. This will reduce the possibility of missing pulses and erroneous counts.

Second, they should ensure that the encoder’s signal is monitored at all times. This will help them elevator encoder detect any failures in the system.

Third, they should use a time base to reference the encoder’s output signals. This will help them achieve a higher resolution on position than just monitoring the index pulse transitions on the A channel.

Finally, they should ensure that the encoder’s mounting is precise and stable. This will keep the encoder from slipping and will ensure that it can be used for all future projects.

One way to achieve this is to use a mechanical mount and not an electrical mount. This will help them avoid the potential for a short circuit in the motor shaft.

Another way to achieve this is to use a hollow-bore encoder that is mounted on the non-drive end of the motor shaft. This will allow them to increase the RPM limit without sacrificing accuracy on position.

Lastly, they should check the encoder’s datasheet for any specifications regarding the maximum rotational speed of the motor. This will help them understand the effect of any error in the encoder’s installation on motor torque.

If a malfunction is detected by the controller, it will set a fault bit in the system and disable the inverter and brake 34. This will prevent any possible unintended motion of the elevator car 26.

Temperature

The temperature of your elevator’s hydraulic system can affect the quality of your ride and shorten its life. Large fluctuations in the temperature of the oil can lead to erratic operation and equipment failures, which can reduce productivity in your building.

In order to reduce these problems, the hydraulic power unit must be designed with an adequate thermal balance to maintain a safe, consistent, and high quality ride. This requires consideration of the type of elevator, suspension ratio, and a variety of environmental conditions.

To evaluate this challenge, a theoretical model was developed for an indirect elevator, which is normally used as a standard push type or as a pull type with counterweight. For each type, simulations were carried out using mechanical and electronic control valves under varying design conditions (travel cycles, submersible or external motors, natural air blow (cooling) onto the tank).

According to the model, doubling tank oil volume decreases the balance temperature 8 – 10 percent for submersible units, and 6.7 – 9 percent for external units. Moreover, a blow of 60% of air volume on the tank, which occurs when the elevator car moves, results in a 2.3 to 3.7 percent drop in balance temperature for high-usage elevators and a 17.3 to 21.5 percent reduction for mid-usage elevators.

When designing a hydraulic power unit, it’s important to consider the size and shape of the enclosure as well as the orientation of the cylinder head. This will determine whether a cooler is needed.

Another factor to consider is the encoder. It should be rated to operate elevator encoder at -40degC to 85degC with a recommended top speed of 3000 RPM, which will help protect the encoder from thermal shock, vibrations, and other stresses.

There are a few types of encoders available. Some are primarily designed for servo control systems and have through and blind hollow shafts, while others are more solid-shaft sensors, like the EMI 22 A kit sensor, which operates on an incremental basis. It has a compact size and may be manufactured from EN-AW 2011 aluminum or 1.4305/stainless steel.

Shaft Copying

When an elevator moves up or down a shaft, encoders provide feedback to the lift system. They provide information about the shaft’s position that is needed to help ensure safe braking and precise elevator car movement.

A typical shaft copying system consists of mechanical components such as pulleys, a toothed belt or cord, and an incremental or absolute encoder. The latter type of encoder is ideal for shaft copying applications since it can accurately determine the lift car’s position and forward that information to the control.

Elevator encoders are also used to control elevator doors and monitor the motors that drive the elevator car’s door mechanisms. Encoders need to be hollow-bore designs that are compact enough to fit in the allotted space and offer high resolution for proper door operation.

The most common types of elevator encoders are rotary encoders, which convert rotational motion into electrical signals that can be processed by a computer or other device. This allows an elevator controller to use encoder feedback for speed and position data, and can improve efficiency by eliminating microswitches.

One popular type of rotary encoder is the incremental rotary encoder, which detects changes in the shaft’s angular position rather than an absolute position. This enables the encoder to reset when power is removed from it.

These encoders can be used in both cable-bound and cableless elevators. They can provide a variety of advantages for both systems, such as jerk-free braking and accurate positioning.

Additionally, the rotary encoder can measure the motor’s rotor position so that it can be properly modulated to produce maximum torque output. This is important for permanent magnet (PM) motors, which have become more popular in elevator applications due to their improved performance characteristics.

When deciding on the appropriate type of encoder for your application, consider the size and resolution requirements, the type of circuitry required, and how much information you need. In addition, choose an encoder that offers good signal quality, a wide range of output types, and compatibility with the elevator controls used in your building.