Worm Reducer Preload Structure for Stick-Slip Noise Suppression
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Solution Overview
Problem
Worm reducers with coil springs often generate an abnormal stick-slip sound due to the positional relationship between the bearing and the coil spring, which existing technologies fail to effectively address without increasing the number of parts or complexity.
Innovation Solution
A worm reducer design where the coil spring contacts the bearing's outer peripheral surface and is urged toward the worm wheel using a preload member with a different winding direction, ensuring the coil spring's distal end is positioned within a predetermined range to minimize contact resistance and prevent stick-slip sound, along with a manufacturing method that secures the preload member to the housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the coil spring is positioned close to the bearing to apply urging force, then the urging force effectiveness is improved, but stick-slip sound is generated due to contact between the coil spring and bearing
Solution Approach 1:
A groove is formed on the outer peripheral surface of the bearing to create an intermediary space between the coil spring and bearing. This groove allows the coil spring to apply urging force effectively while preventing direct contact that causes stick-slip sound, thus resolving the contradiction between force effectiveness and sound generation.
2Object-generated harmful factors
If the coil spring is positioned far from the bearing to avoid contact, then stick-slip sound is reduced, but the urging force effectiveness decreases
Solution Approach 1:
The groove on the bearing's outer peripheral surface acts as an intermediary structure that enables the coil spring to maintain effective urging force while being positioned at a distance that avoids direct contact. The groove geometry optimizes the balance between force transmission and contact prevention.
3Device complexity
If the coil spring and preload member have the same winding direction, then the structure is simpler, but abnormal sound is generated due to low contact resistance
Solution Approach 1:
The coil spring and preload member are designed with different winding directions (asymmetric configuration). This asymmetry increases the contact resistance between these components, preventing the stick-slip phenomenon that causes abnormal sound, while maintaining overall structural simplicity through this deliberate directional difference.
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 significantly reduces the likelihood of stick-slip sound generation between the coil spring and the bearing, maintaining optimal inter-shaft distance and preventing collision sounds even under vibration or sudden torque, without adding complexity or parts.
Implementation Method 1
a coil spring that contacts an outer peripheral surface of the bearing and applies an urging force toward the worm wheel
Implementation Method 2
a preload member that is screwed into and fixed to the housing and pressurizes the coil spring
Implementation Method 3
A winding direction of the coil spring is different from a winding direction of a thread of the preload member, and contact resistance between the coil spring and the preload member is greater than contact resistance between the coil spring and the bearing
Data Source
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AI summary
A worm reducer includes a worm shaft (164); a worm wheel (163); a housing (153) that houses the worm shaft (164) and the worm wheel (163); a bearing that holds the worm shaft (164) inside the housing (153); a coil spring (170) that contacts an outer peripheral surface of the bearing and applies an urging force toward the worm wheel (163); and a preload member (155) that is screwed into and fixed to the housing (153) and pressurizes the coil spring (170). A winding direction of the coil spring (170) is different from a winding direction of a thread of the preload member (155), and contact resistance between the coil spring (170) and the preload member (155) is greater than contact resistance between the coil spring (170) and the bearing.