Steering Gear Layout With Axial Overlap for Compact EPS Packaging
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Solution Overview
Problem
Conventional steering devices in electric power steering systems are bulky due to the misalignment of the speed reducer and operating mechanism, leading to inefficient use of space.
Innovation Solution
The steering device is designed with a first gear mechanism that converts rotational direction and a second gear mechanism that decelerates rotation, arranged to overlap each other along a common axial direction, incorporating a drive device that assists steering operations, all within the width of the second gear mechanism, reducing the device's thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the speed reducer and operating mechanism are disposed such that their axial directions intersect, then the functional requirements are met, but the device becomes bulky due to misalignment in the axial direction
Solution Approach 1:
The patent applies dimensional repositioning by moving the operating mechanism from a conventional side-arranged position to a position that overlaps with the speed reducer in the axial direction. This spatial reconfiguration in the third dimension (axial overlap) allows both components to coexist within a reduced overall footprint, resolving the contradiction between functional requirements and device size.
Solution Approach 2:
The operating mechanism is positioned within the axial footprint of the speed reducer, creating a nested spatial arrangement where one component occupies the same axial space as the other. This nesting approach allows the operating mechanism to be housed within the width of the speed reducer, achieving compact integration without compromising functional performance.
2Volume of moving object
If the first gear mechanism and second gear mechanism are arranged to overlap along the axial direction, then the device thickness is reduced, but the alignment precision between components becomes more challenging
Solution Approach 1:
The patent resolves alignment challenges by transitioning from a conventional planar arrangement to a three-dimensional overlapping configuration. By utilizing the axial dimension for component placement, the design achieves compact thickness while managing alignment through spatial separation and integrated housing structures that maintain precise relative positioning.
Solution Approach 2:
The patent integrates the housing structures of the first and second gear mechanisms into a unified assembly, where the cases are combined or closely coupled to maintain precise alignment between the overlapping components. This merging approach ensures that alignment precision is preserved through structural integration rather than relying solely on separate component tolerances.
3Volume of moving object
If the drive device is positioned to overlap the second gear mechanism, then further downsizing is achieved, but the complexity of power transmission increases
Solution Approach 1:
The patent merges the drive device with the second gear mechanism by positioning them to overlap in the axial direction and integrating their power transmission paths. This combination allows the drive device to share space with the gear mechanism while maintaining efficient power flow, reducing overall device thickness without proportionally increasing complexity through shared structural and functional elements.
Solution Approach 2:
The overlapping arrangement enables the second gear mechanism to serve dual functions: both as a speed reduction component and as a structural housing that accommodates the drive device. This multi-functionality approach allows the same spatial region to fulfill multiple roles, achieving compactness without linearly increasing system complexity.
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 achieves further downsizing of the steering device by overlapping components, allowing for a more compact design while maintaining efficient power transmission and reducing torque, weight, and improving operational accuracy.
Implementation Method 1
a first gear mechanism configured to receive rotation of steering wheel operation, convert a direction of the rotation
Implementation Method 2
a second gear mechanism configured to receive the primary rotation output from the first gear mechanism, decelerate the primary rotation
Implementation Method 3
a drive device configured to output a driving force for assisting the steering wheel operation
Data Source
AI summary
A steering device includes: a first gear mechanism configured to receive rotation of steering wheel operation, convert a direction of the rotation, and output converted rotation as primary rotation; and a second gear mechanism configured to receive the primary rotation output from the first gear mechanism, decelerate the primary rotation, and output decelerated rotation. When a second axial direction is defined as an axial direction of an output shaft included in the second gear mechanism, the first gear mechanism is located such that at least a portion of the first gear mechanism falls within a width of the second gear mechanism along the second axial direction.