Backlash-Compensating Gear With Segmented Teeth And Leaf Springs
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Solution Overview
Problem
Existing backlash-compensating gear mechanisms in horology are limited by their unidirectional operation, manufacturing defects, and variations in center distance, leading to poor performance and display precision issues in both directions of rotation.
Innovation Solution
A backlash-compensating gear mechanism featuring groups of consecutive rigid teeth with convex meshing flanks and interleaved leaf springs that extend beyond the tip circle, allowing bidirectional operation and compensating for backlash by ensuring force transmission through rigid teeth in both directions, while being less sensitive to manufacturing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If resilient half-teeth are used to compensate backlash, then backlash is compensated, but the gear can only operate in one direction with good performance
Solution Approach 1:
The gear teeth are segmented into groups of consecutive rigid teeth separated by spaces containing leaf springs. This segmentation allows different parts to serve different functions: rigid teeth for force transmission in both directions, and leaf springs for backlash compensation, enabling bidirectional operation with consistent performance
Solution Approach 2:
Different regions of the gear have different properties: groups of consecutive rigid teeth provide rigidity for bidirectional force transmission, while interleaved leaf springs provide resiliency for backlash compensation. This local differentiation resolves the contradiction between unidirectional and bidirectional operation
2Reliability
If resilient half-teeth are used to compensate backlash, then backlash is compensated, but the gear is very prone to manufacturing defects and variations in center distance
Solution Approach 1:
By segmenting the gear into groups of rigid teeth with spaces for leaf springs, the design reduces sensitivity to center distance variations. The leaf springs accommodate small variations in center distance while the rigid teeth maintain precise meshing, improving manufacturing tolerance
Solution Approach 2:
The leaf springs provide a mechanism to accommodate variations in center distance through elastic deformation. This parameter change capability allows the gear to maintain proper meshing and backlash compensation even when center distance varies from theoretical values
3Reliability
If resilient teeth transmit torque alternately with rigid teeth, then backlash is compensated, but torque and rotational speed vary affecting display precision
Solution Approach 1:
The gear uses groups of consecutive rigid teeth instead of alternating single rigid and resilient teeth. This ensures that torque is always transmitted through rigid teeth, eliminating torque and speed variations, while the leaf springs in the spaces maintain backlash compensation
Solution Approach 2:
The design separates the functions of torque transmission and backlash compensation to different components: rigid teeth handle torque transmission consistently in both directions, while leaf springs handle backlash compensation locally in the spaces between tooth groups, ensuring stable torque transmission and display precision
4Reliability
If resilient teeth are used to transmit torque, then backlash is compensated, but friction increases and performance decreases
Solution Approach 1:
By using groups of consecutive rigid teeth with leaf springs in the spaces, the design ensures that torque transmission always occurs through rigid tooth-flank contact, eliminating the high friction associated with resilient tooth transmission, while leaf springs maintain backlash compensation
Solution Approach 2:
The design localizes the resilient element (leaf spring) to only perform backlash compensation without participating in torque transmission. The rigid teeth handle all torque transmission with low friction, while the leaf springs absorb only the minimal forces needed for backlash compensation, significantly reducing energy loss
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 mechanism enables stable and precise bidirectional operation with improved resistance to manufacturing defects and variations in center distance, maintaining high performance and display precision in both directions of rotation.
Implementation Method 1
the other half-tooth having a recess which allows it to be resiliently deformed in the event of locking
Implementation Method 2
one tooth being fixed and completely rigid... transmit the torque to the other mobile alternately by a rigid tooth
Data Source
AI summary
A backlash-compensating mobile (1) intended to form a gear with a second mobile (2) and having rigid teeth (4, 5) and backlash-compensating leaf springs (16), is characterized in that the rigid teeth (4, 5) are distributed in groups of consecutive teeth, each group having a first rigid tooth (4) and a second rigid tooth (5) having respective mutually facing meshing flanks (10, 11) to permit the displacement of the second mobile (2) in both directions, and in that the leaf springs (16) are interleaved between these groups in spaces not intended to receive the teeth (3) of the second mobile (2), and extend beyond the tip circle (Ca) of the rigid teeth (4, 5) in order to cooperate with the second mobile (2).