Elevator Safety Brake With Self-Regulating Braking Moment
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Solution Overview
Problem
Progressively operative safety brakes for elevators face challenges in predicting and managing braking forces, leading to over-dimensioning and increased weight and cost, while constantly operative brakes lack safety during reduced braking friction conditions.
Innovation Solution
A self-regulating safety brake with a centrifugal regulator that maintains a constant braking moment by using a switch mechanism to adjust spring biasing based on friction conditions, ensuring consistent brake force through a balanced position adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a progressively operative safety brake is used, then the brake force increases continuously to ensure stopping, but the required safety margin leads to over-dimensioning and increased weight
Solution Approach 1:
The brake device transitions from a static, continuously progressive braking system to a dynamic system with distinct operational phases. The brake operates in a first phase with high brake force for initial deceleration, then transitions to a second phase with reduced brake force for final stopping, optimizing the force profile throughout the braking process rather than maintaining continuous maximum force
Solution Approach 2:
The invention changes the brake force parameter over time through controlled phases. The brake force is not continuously progressive but is modulated through different phases with different force levels, allowing the system to achieve reliable stopping while reducing the peak forces that would require over-dimensioning
2Weight of moving object
If a constantly operative safety brake with constant braking moment is used, then the forces can be predicted and weight reduced, but safety is compromised when braking friction is reduced due to moisture or oil
Solution Approach 1:
The control device monitors brake performance and detects when the brake force is insufficient to achieve the required deceleration. When reduced friction is detected (through insufficient deceleration performance), the control device responds by increasing the brake force in the second phase, ensuring safety is maintained despite friction reduction from moisture or oil
Solution Approach 2:
The system prepares for potential friction reduction by having a controlled mechanism to increase brake force during the second phase. The control device is designed to anticipate and counteract the effect of reduced friction by automatically adjusting brake force upward when performance thresholds are not met
3Reliability
If a progressively operative safety brake is used, then safety is maintained, but the braking distance is limited by the maximum force the system can withstand
Solution Approach 1:
The brake device uses dynamic phase transitions to extend braking distance capability. By switching from a first phase with high brake force for initial deceleration to a second phase with controlled brake force, the system can manage the cumulative effect of braking over a longer distance without exceeding maximum force limits, thereby extending the effective braking distance
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
The solution provides a reliable and safe braking system that maintains a constant braking moment, minimizing the risk of brake collapse and maintaining safety even with reduced friction, by dynamically adjusting the spring biasing to match changing friction conditions.
Implementation Method 1
When exceeding a pre-determined rotation speed, the centrifugal regulator is provided to activate and couple in a rotation brake
Implementation Method 2
a spring assembly as well as a centrifugal regulator with a shaft that rotates due to a coupling to the movement of the elevator car
Implementation Method 3
one or a plurality of centrifugal bodies on the regulator shaft are engaging with an interior side of the rotatable brake part. In this way, the said rotatable brake part is entrained in the rotation of the regulator shaft, whereby a sleeve is caused to bias a spring assembly by travelling along a shaft. As the spring assembly is biased, the rotatable and the fixed brake part are squeezed increasingly harder together
Data Source
AI summary
The invention relates to a safety brake for an elevator, a centrifugal regulator and a way of using this in a safety brake. According to the invention, the safety brake comprises a centrifugal regulator (3), a shaft (4), which rotates due to a coupling (5) to the elevator, a first (6) and a second (8) brake part movable against each other with friction surfaces (10, 11), the first brake part being rotatable with the shaft, a spring assembly (30) with which the brake parts are spring-biased with a pressure force, on release the centrifugal regulator is provided to couple the shaft (4) to the first brake part (6) to force rotation on it. The safety brake is self-regulating by comprising the pressure-relieving arrangement provided, due to the rotation of the shaft (4), to relieve the spring biasing by pressing the first brake part (6) towards the spring assembly's (30) spring action and thus from the other brake part (8), until a balanced position is obtained whereby both brake parts (6, 8) frictionally slide against each other.