Tension Device Pawl for Anti-Skid Chain Blocking
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Solution Overview
Problem
Existing tensioning devices for anti-skid chains, such as snow chains, are complex and require high precision due to multiple ratchet wheels and positions, making them difficult to operate and maintain, and they cannot efficiently achieve alternating blockages in opposite directions.
Innovation Solution
A tensioning device with a single pawl element that engages different contact surfaces in a toothed ring for two blocking positions, allowing movement in one direction while blocking in the opposite direction, using a non-rotatably connected lever and spring-loaded pawl for efficient and compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple ratchet wheels and pawls are used to achieve blocking in both directions, then the blocking functionality is improved, but the device complexity increases
Solution Approach 1:
The patent combines multiple blocking functions into a single pawl element that can engage with different contact surfaces on the toothed ring. Instead of using separate pawls for each blocking direction, one pawl with multiple contact surfaces performs the function of multiple pawls, thereby reducing device complexity while maintaining blocking reliability
Solution Approach 2:
The single pawl element is designed to perform multiple functions by engaging with different contact surfaces on the toothed ring. The same pawl can block movement in different directions depending on which contact surface engages with the corresponding tooth flank, making the component universal and multi-functional
2Reliability
If multiple ratchet wheels and pawls are used to achieve blocking in both directions, then the blocking functionality is improved, but the manufacturing precision requirements increase
Solution Approach 1:
By merging multiple blocking functions into a single pawl, the number of precision-critical interfaces is reduced. Instead of requiring precise alignment between multiple pawls and multiple ratchet wheels, the design requires precise alignment between one pawl and one toothed ring, simplifying manufacturing precision requirements
3Device complexity
If a single pawl element with multiple contact surfaces is used, then the device complexity is reduced, but the operational safety must be maintained
Solution Approach 1:
The pawl is designed with different contact surfaces having different local qualities - each contact surface is specifically shaped and positioned to engage with corresponding tooth flanks for specific blocking directions. This local differentiation ensures that each contact surface provides appropriate engagement characteristics for its specific function, maintaining operational safety
Solution Approach 2:
The contact surfaces on the pawl are asymmetrically arranged and shaped to match the asymmetric tooth flanks of the toothed ring. This asymmetric design ensures proper engagement geometry for blocking in different directions, with each contact surface optimized for its specific engagement scenario, thereby maintaining operational safety
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 simplifies the device by reducing components and enhancing operational safety, enabling efficient and symmetric blocking in both directions with self-locking functionality, reducing complexity and improving usability.
Implementation Method 1
a spring element can advantageously be provided, which on one side of the locking pawl - e.g. facing away from the ring gear or on the front side - is arranged and resiliently presses on the pawl
Implementation Method 2
the at least one run-on surface at least supports a tooth flank of the toothed ring (namely, acts as a bearing surface) and inhibits the movement of the toothed ring in this tooth flank direction
Data Source
Figure 1~3
Figure 4~5
AI summary
The device has a blocking pawl moved between two end positions corresponding to blocking positions by an actuating member. The blocking pawl is engaged with ramp surfaces in a gear ring in the end positions. The ramp surfaces support sprockets of the gear ring to stop the movement of the gear ring in a sprocket direction. The ramp surfaces are arranged in different positions to cooperate with the sprockets of different orientations. The actuating member has a tensioning strand moved in a housing in the blocking positions.