Elevator Motor Torque Monitoring for Brake Dragging Detection
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Solution Overview
Problem
Existing methods for monitoring brake dragging in elevators are inadequate, as they rely on expensive, unreliable, and difficult-to-install brake switches, which can fail to detect incomplete brake opening, leading to prolonged brake dragging and elevator service interruptions.
Innovation Solution
A method that calculates the motor torque estimate and compares it to the realized motor torque during elevator operation, generating a signal for possible brake dragging if the difference meets predetermined criteria, allowing for the detection of brake dragging without additional hardware and in conjunction with existing brake monitoring methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If brake switches are used to monitor brake opening, then brake dragging can be detected, but the system becomes expensive, unreliable, and difficult to install
Solution Approach 1:
The existing motor and torque calculation system perform dual functions: controlling elevator motion and monitoring brake dragging. The motor controller calculates motor torque estimate from motion profile and compares it with actual torque from current measurements, using this existing data to detect brake dragging without additional monitoring hardware.
Solution Approach 2:
The motor controller is made multi-functional by enabling it to perform both elevator motion control and brake dragging monitoring. The same processor that controls the motor also analyzes torque differences to detect brake dragging, eliminating the need for separate monitoring devices.
2Measurement precision
If brake switches are installed to detect brake dragging, then monitoring capability is improved, but installation difficulty and cost increase
Solution Approach 1:
The motor controller utilizes its existing computational resources and sensor data (current measurements) to perform brake monitoring functions, eliminating the need for external sensors or additional installation work.
Solution Approach 2:
The mechanical brake switch system is replaced with an electronic/software-based monitoring approach. The motor controller uses electrical current measurements and torque calculations to detect brake dragging, substituting mechanical sensing with electrical sensing and computational analysis.
3Reliability
If brake switches are used for monitoring, then brake dragging detection is possible, but the system becomes expensive
Solution Approach 1:
The motor controller performs brake monitoring as a free byproduct of its normal operation, using existing current measurements and torque calculations without requiring additional expensive hardware or increasing system cost.
Solution Approach 2:
Instead of using physical brake switches, the system creates a virtual monitoring capability within the motor controller software, using computational models to replicate the detection function that would otherwise require separate hardware.
4Productivity
If traditional brake monitoring methods are used, then brake dragging may be detected, but service interruptions occur due to undetected incomplete brake opening
Solution Approach 1:
The motor controller continuously compares the calculated motor torque estimate with the actual motor torque during elevator operation. This real-time feedback mechanism detects discrepancies indicating incomplete brake opening, allowing immediate identification of brake dragging issues before they cause service interruptions.
Solution Approach 2:
The torque comparison monitoring operates continuously during elevator runs, providing constant surveillance of brake function rather than relying on intermittent switch signals. This continuous monitoring ensures brake dragging is detected regardless of when it occurs during operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively identifies brake dragging issues during normal elevator operation, ensuring proper brake function and reducing service interruptions by determining if the brake opens correctly, without requiring new hardware installations.
Implementation Method 1
When current passes through the coil of the electromagnetic brake, then the attraction between the electromagnetic core and the armature moves the brake shoe away from the brake surface.
Data Source
AI summary
A method includes calculating a motor torque estimate for an electric motor of an elevator in an elevator run, determining a difference between the calculated motor torque estimate and a realized motor torque during the elevator run, and generating a signal indicating possible brake dragging based on the difference between the motor torque estimate and the realized motor torque.