Worm Gear Reducer Holder Structure for Backlash Suppression
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Solution Overview
Problem
Existing worm reduction gears in electric power steering systems experience backlash and teeth striking sounds due to dimensional and assembly errors, which are not effectively suppressed by current preload mechanisms.
Innovation Solution
The worm reduction gear incorporates a housing, worm wheel, worm, bearing, inner diameter side holder, outer diameter side holder, and an elastic urging member, where the inner diameter side holder is elastically urged against the outer diameter side holder to convert the urging force into a force that suppresses backlash and meshing position variations between the worm teeth and wheel teeth, thereby reducing teeth striking sounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a worm reduction gear is used with traditional bearing support, then the structure is simple and easy to manufacture, but backlash and teeth striking sounds occur due to dimensional and assembly errors
Solution Approach 1:
The holder is divided into an inner diameter side holder and an outer diameter side holder, which can rotate relative to each other. This segmentation allows the system to accommodate dimensional and assembly errors while maintaining meshing stability, resolving the contradiction between manufacturing simplicity and meshing reliability.
Solution Approach 2:
The inner diameter side holder is made rotatable relative to the outer diameter side holder, transforming a static structure into a dynamic one. This dynamic capability allows the holders to self-adjust and absorb errors, improving meshing stability without significantly complicating the manufacturing process.
2Reliability
If preload pads and torsion coil springs are used to suppress backlash, then the meshing stability improves, but the device complexity increases
Solution Approach 1:
The function of suppressing backlash and absorbing errors is extracted from complex preload mechanisms (preload pads and torsion coil springs) and transferred to the rotational degree of freedom between the inner and outer diameter holders. This simplifies the overall structure while maintaining reliability.
Solution Approach 2:
The relative rotation between the inner diameter side holder and outer diameter side holder acts as an intermediary mechanism that absorbs dimensional and assembly errors, replacing the need for complex preload pads and springs, thus reducing device complexity while maintaining backlash suppression.
3Reliability
If the inner diameter side holder is made rotatable relative to the outer diameter side holder, then dimensional and assembly errors are absorbed and meshing stability is maintained, but the device complexity increases
Solution Approach 1:
The rotational mechanism between the inner and outer diameter holders serves multiple functions: it absorbs dimensional errors, compensates for assembly errors, and maintains meshing stability. This multi-functionality justifies the increased structural complexity by delivering comprehensive error absorption capabilities.
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 effectively prevents the generation of teeth striking sounds and maintains a stable meshing state by absorbing dimensional and assembly errors, improving the operational reliability of the worm reduction gear.
Implementation Method 1
an elastic urging member, configured to elastically urge the inner diameter side holder against the outer diameter side holder in a direction of rotating in the other circumferential direction
Data Source
AI summary
A worm reduction gear, including: an inner diameter side holder in which a bearing is internally fitted and held; an outer diameter side holder which includes a holder holding part in which the inner diameter side holder is internally fitted and held so as to be able to be relatively rotated and moved and to be displaced in a direction orthogonal to a center axis of a worm wheel and a center axis of a worm, and which is internally fitted and held in a holding recessed part of a housing; and an elastic urging member in a circumferential direction which elastically urges the inner diameter side holder against the outer diameter side holder in a direction of rotating in the circumferential direction.