Split Ratchet Wheel for Elevator Braking
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Solution Overview
Problem
Existing breaking devices for elevator and escalator systems are difficult to install in existing drives, as they require specific preparation and accessibility, which is not always feasible, especially for drives with non-standard surface contours.
Innovation Solution
A ratchet wheel design comprising two halves that form a ring with a gap, allowing for clamping onto the drive shaft using screws or form-fit mechanisms, enabling torsional rigidity without axial accessibility, and a spring-loaded pawl for directional locking in emergency situations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ratchet wheel is fixed to the drive shaft in a torsionally rigid manner using conventional mounting methods, then the breaking device can effectively hold fast the elevator car in emergency situations, but the device cannot be added to existing drives as the drive shaft is neither prepared for receiving a ratchet wheel nor sufficiently accessible
Solution Approach 1:
The ratchet wheel is divided into two separate half-ratchet wheels that can be installed independently on the drive shaft. This segmentation allows the components to be mounted without requiring complete disassembly or complex preparation of the drive shaft, making installation feasible on existing drives while maintaining torsional rigidity when assembled together
Solution Approach 2:
The half-ratchet wheels are designed to be mounted radially onto the drive shaft rather than axially, changing the dimension of installation approach. This radial mounting method allows access from the side of the drive shaft, bypassing the limitation of insufficient axial accessibility in existing drives
2Strength
If the drive shaft is prepared for receiving a ratchet wheel through conventional methods, then the ratchet wheel can be mounted torsionally rigidly, but this requires modification of existing drives which is not always feasible
Solution Approach 1:
The half-ratchet wheel design with radial mounting capability creates a universal solution that can be adapted to various drive shaft configurations without requiring specific preparation or modification. The design works with both new and existing drives, including those with non-standard surface contours, enhancing versatility while maintaining sufficient torsional rigidity for emergency breaking functions
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 allows for easy installation on various drive shaft configurations without modifying the existing drive, providing a simple and effective means to lock the elevator car or escalator steps in one direction while allowing movement in the opposite direction for evacuation, minimizing operational disruption.
Implementation Method 1
a spring mechanism (7) pressing the pawl (4) against the ratchet wheel (1) in a spring-loaded manner
Implementation Method 2
a friction sleeve (12) which is configured to increase friction between the ratchet wheel (1) and the drive shaft (2)
Data Source
Figure 1a~1b
Figure 2a~2c
Figure 3a~3b
AI summary
The invention relates to a braking device (100) for an elevator car (31), comprising a ratchet wheel (1) being mountable on a drive shaft (2), a pawl (4) configured to engage with the ratchet wheel (1), so that the ratchet wheel (1) is locked in a first rotational direction (5.1) and unlocked in a second rotational direction (5.2), wherein the ratchet wheel (1) comprises a first half (1.1) and a second half (1.2), each of which is configured to half-enclose the drive shaft (2), and wherein the first half (1.1) and/or the second half (1.2) comprise means for fasten the first half (1.1) and the second half (1.2) together and means for fasten the ratchet wheel (1) to the drive shaft (2) in a torsionally rigid manner. The invention further relates to a ratchet wheel (1), a method for assembling a ratchet wheel (1), an elevator drive (34) and an elevator system (200).