Recirculating Ball Power Steering Torque Transfer
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Solution Overview
Problem
Conventional power steering systems for vehicles lack efficient torque transfer mechanisms that can variably supply power assistance based on driving conditions, often relying on hydraulic boosts which are complex and less efficient.
Innovation Solution
A recirculating ball power steering system that includes a first ball screw and ball nut in torque-transfer communication through ball bearings, meshed with a sector gear, and an electric motor that selectively supplies torque to the sector gear via a drive unit, enabling variable torque transfer without hydraulic assistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If hydraulic boost systems are used for power steering, then power assistance is provided, but device complexity increases and efficiency decreases
Solution Approach 1:
The patent replaces the hydraulic mechanical system with an electric motor system. The electric motor (120) directly drives the ball screw (114) through a drive unit, eliminating the need for hydraulic pumps, reservoirs, hoses, and boost mechanisms. This substitution of mechanical-hydraulic components with an electric actuation system reduces overall device complexity while maintaining power assistance capability.
Solution Approach 2:
The patent extracts and removes the hydraulic boost mechanism from the steering system. By eliminating the hydraulic subsystem entirely and using only the electric motor and ball screw mechanism for power assistance, the design simplifies the overall system architecture while preserving the essential function of providing torque assistance to the driver.
2Power
If hydraulic systems are used for torque transfer, then power assistance is achieved, but energy efficiency is reduced
Solution Approach 1:
The patent substitutes the energy-inefficient hydraulic system with an electric motor system. Electric motors inherently have higher energy efficiency compared to hydraulic systems, as they directly convert electrical energy to mechanical torque without the energy losses associated with hydraulic fluid circulation, pressure maintenance, and mechanical friction in hydraulic components. This substitution directly addresses the energy efficiency concern.
3Adaptability or versatility
If variable torque transfer is implemented, then adaptability to driving conditions improves, but conventional systems lack this capability
Solution Approach 1:
The patent implements a dynamic control system where the electric motor's torque output can be varied in real-time based on driving conditions. The controller (126) receives inputs from sensors (such as steering angle sensor 104 and torque sensor 108) and adjusts the motor torque accordingly, enabling variable power assistance that adapts to different steering conditions without requiring complex mechanical adjustment mechanisms.
Solution Approach 2:
The patent incorporates feedback mechanisms through various sensors that monitor steering wheel position, torque applied by the driver, and vehicle operating conditions. The controller uses this feedback information to dynamically adjust the electric motor's torque output, providing optimal power assistance across different driving scenarios. This electronic feedback control achieves variable adaptability without adding significant mechanical 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 system provides efficient and variable power assistance to the steering system, enhancing torque transfer and reducing driver effort without the complexity of hydraulic systems, adaptable to different driving conditions.
Implementation Method 1
The first ball nut is in torque-transfer communication with the first ball screw through a plurality of ball bearings
Data Source
AI summary
A power steering system for transferring torque to a sector gear includes a first ball screw and a first ball nut circumscribing the first ball screw. The first ball nut is in torque-transfer communication with the first ball screw through a plurality of ball bearings and is meshed or engaged with the sector gear for torque transfer therewith. An electric motor is configured to selectively supply torque to the sector gear through the first ball nut.