Why Elevator Encoders are the Unsung Heroes of Modern Skyscrapers

Imagine stepping into an elevator and not reaching your floor precisely, or experiencing jerky movements during the ride. That’s where elevator encoders come in—these unsung heroes ensure a safe and comfortable journey every time.

Elevator encoders are like the eyes and ears of the elevator’s control system. They translate the elevator’s physical movements—position and speed—into digital signals for the computer’s brain. This information is crucial for the computer to precisely control various aspects of the elevator, adhering to safety standards like ASME A17.1 (US) and CAN/CSA B44 (Canada).

In an elevator system, encoders play a crucial role by informing the controller about the precise position of the elevator car. Specifically, they provide motion feedback that helps ensure the elevator stops exactly level with the floor. This precise positioning is what allows the doors to open right at the floor level, facilitating easy and safe entry and exit. Without the use of encoders, passengers might face the inconvenience of stepping up or down when entering or exiting, rather than walking straight onto an even floor.

Elevator Encoder

Here’s how these tiny powerhouses contribute to a seamless elevator experience:

• Precise Floor Stops: Encoders ensure the elevator car stops perfectly level with the floor, eliminating any awkward gaps or bumps.
• Smooth Speed Control: By monitoring speed, encoders help the computer maintain a comfortable and consistent pace throughout the ride.
• Safe Door Operation: Encoders provide feedback on door position, allowing for smooth opening and closing, preventing accidents.
• Accurate Positioning: Encoders track the elevator’s vertical movement, guaranteeing it reaches the desired floor.
• Governor System Support: Encoders work with the governor system to prevent over speeding, adding an extra layer of safety.

In short, elevator encoders are the silent guardians of your elevator experience. They guarantee a safe, smooth, and comfortable ride, every single time.

Deep Dive into Elevator Encoders: Keeping Your Ride Smooth and Safe

Elevator encoders are the unsung heroes behind every smooth and safe elevator ride. Let’s delve deeper into how these workhorses contribute to various aspects of elevator operation:

1. Motor Commutation and Speed Control:

Imagine a gearless traction motor elevator. Here, encoders monitor speed and position while also controlling the motor (commutation). While absolute encoders are common for commutation, incremental encoders specifically designed for elevators exist. For these incremental encoders to function in commutation, they require separate U, V, and W channels on the code disc for controlling the corresponding channels of the brushless motor.

For speed control, a hollow-bore encoder typically sits on the motor shaft’s non-drive end. Since speed, not positioning, is the focus here, a cost-effective incremental encoder can deliver excellent performance.

Choosing the Right Encoder:

• Signal Quality: The key is a clean signal with well-defined square-wave pulses. This is especially crucial if edge detection or interpolation is involved.
• Wiring: Minimize noise by keeping signal wires away from power cables and using shielded twisted-pair cabling.
• Installation: The encoder mounting point on the motor shaft should have minimal runout (ideally less than 0.001 inches) to prevent uneven bearing load and potential failure.

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2. Elevator Door Motor Control:

Encoders also monitor the automatic elevator doors. A compact, hollow-bore encoder, typically mounted on the car’s top, tracks the door motor, ensuring complete opening and closing. Due to slow door movement at extremes of opening/closing, high-resolution encoders are necessary.

3. Car Positioning with Follower-Wheel Encoders:

These encoders guarantee the car reaches the designated floor level. They consist of an encoder measuring wheel with an encoder mounted on its hub. Mounted on the car’s top or bottom, the wheel presses against a hoist-way structural member. The encoder tracks the wheel’s rotation while the vehicle is moving and converts it into the controller’s preferred car position or journey distance.

Important Considerations:

• Misalignment Sensitivity: Follower-wheel encoders are susceptible to misalignment and require proper positioning.
• Preload Balancing Act: The wheel needs sufficient pressure to ensure rolling, but excessive force can strain the bearing and lead to premature failure.

4. Governor System and Safety:

Encoders play a vital role in preventing over-speeding. A separate elevator governor assembly, with a wire running over sheaves and connected to a safety-trip mechanism, relies on encoder feedback. This feedback helps the controller detect when car speed exceeds the threshold, triggering the safety mechanism.

Governor’s Encoder Requirements:

• Focus on speed: Since position is irrelevant here, a moderate-resolution incremental encoder suffices.
• Safety-First Approach: Utilize proper mounting and wiring techniques. If the governor is part of a larger network, employ a safety-rated encoder communication protocol.

In conclusion, elevator encoders are the silent guardians of your ride, ensuring smooth operation, precise floor stops, and most importantly, safety. Their selection and installation require careful consideration for a comfortable and secure elevator experience.