Elevator Safety Brake Actuator Position Sensing by Solenoid Inductance
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Solution Overview
Problem
Existing electronic safety actuators for elevator brakes rely on mechanical switches for state monitoring, which have a short lifespan and generate noise, and alternative magnetic sensors are expensive and not cost-effective.
Innovation Solution
The use of a measurement circuit to detect changes in the inductance of the solenoid based on the proximity of a permanent magnet, eliminating the need for mechanical switches and expensive magnetic detectors, by measuring the inductance change to determine the position of the safety actuator using existing components within the actuator control circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a mechanical switch is used to monitor the actuator state, then the actuator position can be detected, but the device has a short lifespan and generates noise
Solution Approach 1:
The patent replaces the mechanical switch with an electronic sensing system that uses a sensor to detect the position of the actuator component. The sensor generates an actuator state signal that is processed by a controller to determine whether the brake is engaged or disengaged. This substitution eliminates mechanical contact, thereby extending device lifespan and reducing noise while maintaining accurate actuator state detection.
2Reliability
If a magnetic sensor is used to detect actuator position contactlessly, then the device lifespan is extended and noise is reduced, but the cost increases significantly
Solution Approach 1:
The patent makes the sensor serve multiple functions: it detects the position of the actuator component to determine brake engagement state, and it also provides information for controlling the solenoid activation. By making the sensor multi-functional, the patent reduces the need for additional components and justifies the sensor cost through enhanced system efficiency and reduced component count.
Solution Approach 2:
The system uses the sensor data to automatically control the solenoid activation without requiring external intervention or additional complex sensing systems. The controller processes the actuator state signal and autonomously determines when to activate or deactivate the solenoid, making the system self-regulating and reducing the need for expensive additional control components.
3Ease of operation
If a solenoid holds the magnet in place during normal operation, then the brake remains disengaged, but power failure causes unintended brake engagement
Solution Approach 1:
The patent implements a feedback control system where the sensor continuously monitors the actuator component position and sends signals to the controller. The controller uses this feedback to determine the brake engagement state and appropriately control the solenoid. This feedback mechanism allows the system to detect and respond to power failure conditions, preventing unintended brake engagement while maintaining normal 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 solution provides a cost-effective, long-lasting, and noise-reduced method for monitoring the state of the safety actuator, enabling reliable detection of the brake position without the need for new expensive components, and ensures the elevator's safety by accurately determining the engagement state of the brake.
Implementation Method 1
The inductance of the solenoid is dependent on the magnetic field in which it is situated, which is in turn affected by the permanent magnet. Thus as the proximity of the permanent magnet to the solenoid changes, the inductance of the solenoid changes
Implementation Method 2
The inductance of the solenoid is dependent on the magnetic field in which it is situated, which is in turn affected by the permanent magnet
Implementation Method 3
the solenoid applying a repulsive force, or it may be that the solenoid holds the component (e.g. magnet) in place during normal (non-braking) operation (i.e. the solenoid applying an attractive force)
Data Source
Figure 1a~1b
Figure 2~3
Figure 4
AI summary
An electronic safety actuator for an elevator safety brake, comprising: a solenoid; a permanent magnet, movable by the solenoid between a first position proximate to the solenoid and a second position distal from the solenoid; and a measurement circuit arranged to measure the inductance of the solenoid and thereby detect the position of the permanent magnet. The inductance of the solenoid is dependent on the magnetic field in which it is situated, which is in turn affected by the permanent magnet. Thus as the proximity of the permanent magnet to the solenoid changes, the inductance of the solenoid changes (increases or decreases). The change in inductance that occurs in the solenoid of an elevator safety actuator is significant enough to be measurable electronically and this measurement can be used to determine the position of the permanent magnet and thus of the safety actuator. Such measurement can therefore take the place of the mechanical switch that has previously been used and without requiring a new expensive magnetic detector to be installed in its place. Instead, the position of the actuator can be determined using the existing components together with a new and inexpensive measurement circuit as part of the actuator control circuit.