Electric Power Steering Torque Amplification for Heavy Vehicles
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Solution Overview
Problem
Hydraulic power steering systems are inadequate for trucks and buses requiring large steering forces, limiting the implementation of advanced features like automatic parking, lane keeping, and autonomous driving due to the lack of electronic control devices.
Innovation Solution
An electric power steering apparatus with a torque angle sensor, motor, reducer, and sliding member system that amplifies steering torque and includes redundant motors for reliability, enabling automatic parking, lane maintenance, and autonomous driving.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If hydraulic power steering apparatus is used to provide high output for large steering force, then steering force is sufficient, but electronic control functions cannot be implemented
Solution Approach 1:
The patent replaces the hydraulic power steering system with an electric power steering system that uses a motor to provide steering assistance. This substitution eliminates the need for hydraulic components (pump, reservoir, hoses) while providing sufficient steering force through electromagnetic actuation, thereby enabling integration of electronic control functions for automated driving applications.
2Adaptability or versatility
If electric power steering apparatus is used to enable electronic control functions, then automated driving functions can be implemented, but steering force may be insufficient for trucks and buses
Solution Approach 1:
The patent segments the power transmission path into multiple stages with separate reduction gears (first reduction gear and second reduction gear) to achieve high overall reduction ratio. This segmentation allows the motor to operate at optimal speed while delivering sufficient torque through cumulative reduction, enabling both electronic control functionality and adequate steering force for heavy vehicles.
Solution Approach 2:
The patent introduces a dual-gear reduction mechanism that adds a dimensional layer to the power transmission system. By incorporating both a first reduction gear connected to the motor shaft and a second reduction gear connected to the rack, the system achieves high torque multiplication in an extended transmission path, providing sufficient steering force while maintaining electronic controllability.
3Force
If high reduction ratio is used to amplify steering torque, then steering force is increased, but durability of power transmission parts deteriorates
Solution Approach 1:
The patent divides the high reduction ratio into two separate reduction stages (first reduction gear and second reduction gear), which distributes the mechanical stress across multiple components rather than concentrating it in a single high-ratio gear. This segmentation reduces the load on individual transmission parts, improving their durability while achieving the required torque amplification.
Solution Approach 2:
The patent incorporates a sliding member that can dynamically adjust its position along the rack to accommodate varying steering conditions. This dynamic element allows the system to optimize the engagement of gear teeth and distribute loads more evenly during operation, reducing wear on power transmission components while maintaining high steering torque 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 vehicles to steer autonomously and provides enhanced driver convenience by supporting additional functions such as automatic parking, lane maintenance, and autonomous driving, even in trucks and buses with large steering forces.
Implementation Method 1
the electric power steering apparatus is a steering system that assists the steering wheel's operating force with the power of the motor
Implementation Method 2
a sliding member having an inner screw groove corresponding to the outer screw groove formed on an inner circumferential surface thereof, coupled to the second output shaft via a ball, and sliding in an axial direction to operate a link connected to vehicle wheels
Data Source
AI summary
An electric power steering apparatus according to the present embodiments comprises an input shaft connected to an steering shaft, a first output shaft coupled to the input shaft, a first gear provided at one end of the first output shaft, a second gear meshed with the first gear, a second output shaft provided with the second gear at one end and having an outer screw groove formed on an outer circumferential surface of a position spaced apart from the second gear in an axial direction and rotating in conjunction with the second gear, and a sliding member having an inner screw groove corresponding to the outer screw groove formed on an inner circumferential surface thereof, coupled to the second output shaft via a ball, and sliding in an axial direction to operate a link connected to vehicle wheels.