Cycloidal Gear Structure for Constant Contact Without Backlash
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Solution Overview
Problem
Existing gear mechanisms with cycloid teeth struggle to maintain constant contact with contacting members due to machining accuracy and thermal deformation, leading to backlash and noise, especially in two-stage cycloidal speed reducers with fewer teeth.
Innovation Solution
The gear mechanism incorporates external teeth defined by a cycloid curve that projects outward from the ideal cycloid curve, with through holes formed in the gear to allow elastic deformation during pressure contact, ensuring constant contact with contacting members and preventing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If external teeth are formed inside the ideal cycloid curve to account for machining tolerance, then manufacturing precision is improved, but the external teeth cannot always be in constant contact with contacting members, causing backlash and noise
Solution Approach 1:
The patent modifies the cycloid curve parameters by extending it outward from the ideal cycloid curve to create a modified cycloid curve. This parameter change ensures that the external teeth maintain constant contact with the contacting members during eccentric rotation, eliminating backlash and noise while accounting for machining tolerances and thermal deformation
Solution Approach 2:
The patent introduces through holes in the gear body to enable elastic deformation. This dynamic adjustment allows the gear to adapt its shape during operation, ensuring that the external teeth defined by the modified cycloid curve maintain constant pressure contact with the contacting members despite manufacturing variations and thermal effects
2Reliability
If external teeth are formed outward from the ideal cycloid curve to ensure constant contact, then reliability is improved, but the contacting members interfere with the external teeth, preventing rotation
Solution Approach 1:
The patent extends the cycloid curve outward by a controlled amount to create a modified cycloid curve that projects beyond the ideal cycloid curve. This parameter modification optimizes the tooth profile to maintain constant contact with contacting members while preventing interference, enabling smooth eccentric rotation
Solution Approach 2:
The through holes enable the gear body to undergo elastic deformation during operation. This dynamic flexibility allows the gear to accommodate the extended tooth profile without rigid interference, maintaining constant contact with contacting members while ensuring free rotation
3Manufacturing precision
If the gear is made rigid to maintain tooth shape, then manufacturing precision is maintained, but the gear cannot adapt to thermal expansion and machining tolerance variations, causing loss of constant contact
Solution Approach 1:
The patent introduces through holes that enable the gear body to deform elastically during operation. This dynamic capability allows the gear to adapt to thermal expansion and machining tolerance variations while maintaining the tooth shape defined by the modified cycloid curve, ensuring constant contact with contacting members
Solution Approach 2:
The modified cycloid curve parameters are designed to account for expected thermal expansion and machining variations. Combined with the elastic deformation capability from the through holes, this parameter optimization ensures the gear maintains manufacturing precision while adapting to operational variations
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 configuration enables eccentric rotation of the gear while maintaining constant pressure contact with contacting members, reducing backlash and noise, and enhancing rotational efficiency.
Implementation Method 1
In order to elastically deform the gear by the pressure contact, a plurality of through holes penetrating the gear in a thickness direction of the gear are formed in the gear in the circumferential direction of the gear
Data Source
AI summary
A gear mechanism includes a gear including external teeth, the external teeth including a plurality of tooth parts defined by a cycloid curve, a plurality of contacting members disposed on an outer side and in a circumferential direction of the external teeth, the external teeth being brought into pressure contact with the plurality of contacting members, and a mechanism configured to eccentrically move the gear. A plurality of through holes penetrating the gear in a thickness direction of the gear are formed in the gear in the circumferential direction of the gear, the cycloid curve extends outward from an ideal cycloid curve without the external teeth interfering with the plurality of contacting members, the plurality of contacting members being in contact with the ideal cycloid curve.