Elevator Machinery Brake Activation Timing
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Solution Overview
Problem
Elevators experience a state of free fall during quick stop situations due to the delayed activation of the machinery brake, which can lead to inaccurate stopping and safety hazards, particularly in elevators with gearless hoisting machines, and existing solutions either wear out components or introduce thermal issues or slow down motor disconnection.
Innovation Solution
A method where the disconnection process of the current supply to the elevator motor is delayed by the activation delay of the machinery brake, allowing the brake to engage before disconnecting the motor supply, using a power supply device like a frequency converter to ramp the current to zero, thereby preventing free fall and ensuring controlled deceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the electricity supply to the elevator motor is disconnected immediately when the safety circuit opens, then the motor current is stopped quickly, but the machinery brake activation is delayed causing a free fall state
Solution Approach 1:
The machinery brake activation is triggered in advance by the safety circuit opening signal, before the motor current disconnection is completed. This preliminary activation ensures the brake is ready to engage immediately when motor current drops, preventing the free fall state that would otherwise occur during the current disconnection transition period.
2Speed
If the machinery brake is activated immediately when the safety circuit opens, then the brake shoe engages quickly, but the brake components and electricity supply circuit wear out faster due to increased quenching voltage
Solution Approach 1:
The brake activation process is initiated in advance by the safety circuit opening signal, allowing the electromagnet and brake components to begin their activation sequence before peak current disconnection stresses occur. This timing optimization reduces the intensity of quenching voltage spikes and thermal loads on the brake components during activation, thereby extending their operational lifetime while maintaining fast response.
3Productivity
If the electricity supply to the elevator motor is disconnected before the machinery brake activates, then the motor stops providing braking effect, but the elevator car enters a free fall state with unbraked movement
Solution Approach 1:
The machinery brake activation is triggered in advance by the safety circuit opening signal, ensuring the brake engagement process begins before motor current disconnection is completed. This sequencing ensures continuous braking effect throughout the transition period, eliminating the free fall state and unbraked movement that would otherwise occur during emergency stopping.
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 prevents free fall and ensures safe, accurate stopping of the elevator without compromising normal operation by allowing the machinery brake to engage before disconnecting the motor supply, reducing the duration of free fall and enhancing safety and stopping precision.
Implementation Method 1
the electromagnet of the machinery brake... When the electricity supply is disconnected and when the machinery brake activates
Implementation Method 2
the brake shoe engages mechanically against the braking surface of the hoisting machine to brake the movement
Implementation Method 3
this is a consequence of, inter alia, the effect of the inductance of the electromagnet of the brake
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a method in connection with a quick stop situation of an elevator, and also to a safety device (10) for implementing the method. In the method an activation process of a machinery brake (1) is started and also a disconnection process of the current supply of the elevator motor (3) is started after the starting of the activation process of a machinery brake (1).