Torque Transmission Joint With Oscillating Coupling
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Solution Overview
Problem
Existing torque-transmission systems, such as those in electric power steering devices, face issues with abnormal noise generation due to backlash at spline engagement parts when the central axes of drive and driven shafts are mismatched, which existing solutions fail to completely address.
Innovation Solution
A torque-transmission joint with a coupling having radially protruding convex portions and concave portions on both drive and driven shafts, along with a preload mechanism to elastically press the worm towards the worm wheel, allowing for smooth torque transmission and preventing noise by adjusting the gaps between the shafts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the central axes of drive shaft and driven shaft are mismatched, then torque transmission becomes difficult, but rigid coupling eliminates backlash-related noise
Solution Approach 1:
The coupling is designed to dynamically adjust its position and orientation relative to the drive and driven shafts. The coupling can oscillate and tilt to accommodate axis mismatch while maintaining continuous contact with both shafts, thereby eliminating backlash-related noise while enabling smooth torque transmission between mismatched axes.
Solution Approach 2:
The coupling acts as an intermediary element between the drive shaft and driven shaft. It mediates the connection by absorbing axis mismatch through its own movement, allowing torque transmission without direct rigid alignment between shafts, thus preventing abnormal noise while maintaining transmission reliability.
2Object-affected harmful factors
If elastic member presses worm towards worm wheel, then gear-tooth striking sound is suppressed, but abnormal noise occurs at spline engagement part
Solution Approach 1:
The coupling dynamically adjusts its position to maintain optimal engagement at the spline connection. By allowing the coupling to oscillate and tilt, the system maintains continuous contact between spline elements, eliminating backlash and preventing abnormal noise at the spline engagement part while the elastic member continues to suppress gear-tooth striking sounds.
3Object-generated harmful factors
If spline shaft part and spline hole are engaged without circumferential gap, then abnormal noise is prevented, but axis mismatch causes collision and stress
Solution Approach 1:
The coupling dynamically tilts and oscillates to accommodate axis mismatch between drive and driven shafts. This dynamic adjustment allows the spline engagement surfaces to maintain continuous contact without circumferential gaps, preventing abnormal noise while distributing stress across the engagement surfaces through the coupling's movement capability.
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
Enables smooth torque transmission between mismatched shafts and effectively prevents abnormal noise by allowing the coupling to oscillate and adjust its position relative to the shafts, ensuring proper contact without collision and reducing stress on engagement surfaces.
Implementation Method 1
an elastic member such as a coil spring 11 is provided between the pressing piece 10 and the housing 3. By the coil spring 11, the worm teeth 6 of the worm 8 are pressed towards the tooth part 5 of the worm wheel 4
Implementation Method 2
allowing for smooth torque transmission and preventing noise by adjusting the gaps between the shafts... allowing the coupling to oscillate and adjust its position relative to the shafts
Data Source
AI summary
At a state where central axes of the drive shaft and the driven shaft are matched, the drive-side concave-convex portion is engaged with a half portion on the other axial side of the coupling-side concave-convex portion with a drive-side gap of which a circumferential width size increases towards the other axial side being interposed between a circumferential side surface of each drive-side convex portion and a circumferential side surface of each coupling-side convex portion. At the state where the central axes of the drive shaft and the driven shaft are matched, the driven-side concave-convex portion is engaged with a half portion on one axial side of the coupling-side concave-convex portion with a driven-side gap of which a circumferential width size increases towards one axial side being interposed between a circumferential side surface of each driven-side convex portion and a circumferential side surface of each coupling-side convex portion.