Integrated Steering Gear Output Unit for Low-NVH Torque Transfer
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Solution Overview
Problem
Existing vehicle steering systems face challenges in efficiently transferring torque from the steering wheel to the steerable wheels, particularly in maintaining alignment and reducing noise, vibration, and harshness (NVH) while accommodating varying steering torques.
Innovation Solution
The proposed steering system incorporates a one-piece output unit with a planetary gear stage, a sun gear connected to an electric motor, and a worm wheel mechanism. This configuration allows for efficient torque transfer and alignment, while the elastic element and pressing device help maintain tight meshing of the pinion and worm wheel, reducing NVH.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a traditional gearbox with separate pinion and worm wheel components is used, then the structure is simpler to manufacture, but the alignment precision and NVH performance deteriorate
Solution Approach 1:
The patent merges the pinion, worm wheel, and output shaft into a single integrated one-piece output unit. This integration eliminates alignment errors between separate components, ensuring precise meshing between the pinion and worm wheel, thereby improving manufacturing precision and NVH performance while accepting increased device complexity.
2Object-affected harmful factors
If elastic elements are added to dampen axial movements, then NVH performance is improved, but device complexity increases
Solution Approach 1:
The patent incorporates elastic elements (such as elastomeric material) between the one-piece output unit and the gearbox housing to beforehand cushion axial movements and vibrations. This preemptive damping approach reduces NVH by absorbing mechanical shocks and vibrations before they propagate through the system, improving comfort while accepting additional structural complexity.
3Manufacturing precision
If a one-piece output unit is used, then alignment and meshing precision are improved, but manufacturing complexity increases
Solution Approach 1:
The patent combines multiple components (pinion, worm wheel, output shaft) into a single monolithic one-piece output unit manufactured from a single piece of metal. This merging ensures precise and consistent meshing geometry that cannot be achieved by assembling separate components, thereby improving meshing precision while accepting the challenge of manufacturing a complex single-piece component.
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 system achieves efficient torque transfer and reduced NVH by maintaining precise alignment and utilizing elastic elements to dampen axial movements, effectively addressing the challenges of existing steering systems.
Implementation Method 1
an elastic element between the one-piece output unit and the gearbox
Implementation Method 2
The planetary gear stage includes a sun gear connected to an electric motor such that torque from the electric motor urges the sun gear to rotate relative to the one-piece output unit. The sun gear is meshed with the planetary gear such that rotation of the sun gear urges the planetary gear to rotate and orbit the sun gear.
Implementation Method 3
The worm wheel is connected to a steering wheel via a pinon such that rotation of the steering wheel urges the output unit to rotate about the axis.
Data Source
AI summary
A steering system for use in turning steerable vehicle wheels includes a one-piece output unit connected to a steering wheel such that rotation of the steering wheel urges the output unit to rotate about an axis. The output unit has an output shaft coupled to the steerable vehicle wheels such that rotation of the output unit affects steering of the steerable vehicle wheels. The output unit supports a planetary gear. A sun gear is connected to an electric motor such that torque from the electric motor urges the sun gear to rotate relative to the output unit. The sun gear is meshed with the planetary gear such that rotation of the sun gear urges the planetary gear to rotate and orbit the sun gear. The output unit is urged to rotate about the axis in response to the planetary gear rotating and orbiting the sun gear.