Elastic Torque Transmission Joint for Misalignment and Noise Control
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Solution Overview
Problem
Conventional torque transmission systems in electric power steering devices experience noise and backlash due to misalignment of rotating members, which cannot be completely eliminated by existing biasing mechanisms.
Innovation Solution
A torque transmission joint comprising a first and second rotating member with projection portions, a coupling with recess and support portions, and elastic bodies to ensure smooth torque transmission and noise reduction, even with misaligned axes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a biasing member including a spring is arranged between a housing and a bearing to bias the tip end portion of the worm toward a worm wheel, then backlash at the meshing area between the worm wheel and the worm can be suppressed, but the worm needs to be oscillated and displaced which prevents complete elimination of backlash in the spline-engaged portion between the output shaft and the worm, resulting in noise generation
Solution Approach 1:
The patent introduces a biasing member (spring) as an intermediary element between the housing and the bearing to apply a biasing force on the worm. This mediator enables continuous contact between the worm and worm wheel without requiring oscillation or displacement of the worm, thereby eliminating backlash in the spline-engaged portion between the output shaft and worm while preventing noise generation.
2Object-generated harmful factors
If the spline shaft portion and the spline hole are spline-engaged with no gap in the circumferential direction to eliminate noise, then noise will not be generated at the spline-engaged portion, but the worm needs to be oscillated and displaced which makes it impossible to completely eliminate backlash
Solution Approach 1:
The patent applies preliminary action by pre-positioning the worm in a specific location using the biasing member. The spring applies a biasing force that maintains the worm in optimal contact position with the worm wheel before any operational movements occur. This preliminary positioning eliminates the need for oscillation or displacement during operation, allowing both noise-free spline engagement and complete backlash elimination to be achieved simultaneously.
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 joint effectively transmits torque between misaligned rotating members while preventing noise generation, enhancing the performance of electric power steering devices.
Implementation Method 1
a first elastic body (5) and a second elastic body (6)... respectively held in the circumferential direction between the first projection portions (7) and the first support portions (19)... respectively held in the circumferential direction between the second projection portions (10) and the second support portions (20)
Data Source
Figure 1
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AI summary
A torque transmission joint which can smoothly transmit torque between a pair of rotating members even if central axes of the pair of rotating members do not coincide with each other, and can prevent generation of noise between the pair of rotating members. A torque transmission joint 1 includes a first rotating member 2, a second rotating member 3, a coupling 4, a first elastic body 5, and a second elastic body 6. The coupling 4 has first nail portions 26 provided on at least one of an outer side or an inner side in the radial direction of end portions on a first side in an axial direction of first support portions 19, and second nail portions 29 provided on at least one of an outer side or an inner side in the radial direction of end portions on a second side in the axial direction of the second support portions 20. The first nail portions 26 engage with the first supported portions 36 of the first elastic body 5 from the first side in the axial direction, and the second nail portions 29 engage with second supported portions 43 of the second elastic body 6 from the second side in the axial direction.