Rack-Driven Steering Gear Train for Stable Low-Noise Power Transfer
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Solution Overview
Problem
Conventional rack-driven steering devices suffer from unstable power transfer from the motor, noise, and low durability, particularly in steer-by-wire systems that lack mechanical connections, posing risks to driver safety.
Innovation Solution
A rack-driven steering device design that includes a ball nut coupled with a ball screw, a ball nut gear, a motor gear, and a middle gear to stabilize power transfer while compensating for gear clearance and reducing noise through the use of elastic members and sub gears.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional rack-driven steering device uses direct gear connection between motor and ball nut, then the structure is simple, but the power transfer is unstable and noise is high
Solution Approach 1:
The patent introduces a middle gear as an intermediary component between the motor gear and ball nut gear. This middle gear acts as a mediator that stabilizes power transfer by providing an additional engagement point, reducing clearance issues, and dampening vibrations. The middle gear includes elastic members that further enhance the stabilizing effect while managing the complexity through a structured intermediate stage.
2Reliability
If gear clearance is reduced to improve power transfer stability, then manufacturing precision requirements increase, but noise and operational reliability improve
Solution Approach 1:
The patent employs elastic members attached to the middle gear to dynamically adjust and compensate for gear clearance variations. These elastic members allow the middle gear to flex and maintain optimal engagement with both the motor gear and ball nut gear, effectively managing clearance issues through parameter changes rather than relying solely on tight manufacturing tolerances.
3Object-generated harmful factors
If the gear system is simplified for ease of manufacture, then device complexity is reduced, but operational noise and durability decrease
Solution Approach 1:
The patent segments the gear system into three distinct components: motor gear, middle gear, and ball nut gear. This segmentation allows each component to be optimized independently for noise reduction while maintaining manufacturability. The middle gear with its elastic members creates a buffered transmission path that reduces noise without requiring the entire assembly to be overly complex.
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 solution enables stable power transfer from the motor to the ball nut and ball screw, effectively reducing operational noise and enhancing durability, thereby improving the reliability and safety of steer-by-wire systems.
Implementation Method 1
a ball nut (125) coupled with a ball screw (120) via balls and rotating to slide the ball screw
Implementation Method 2
compensating for the clearance between gears and reducing operational noise
Data Source
AI summary
According to embodiments, there may be provided a rack-driven steering device, comprising a ball nut coupled with a ball screw via balls and rotating to slide the ball screw, a ball nut gear provided on an outer circumferential surface of the ball nut, a motor gear provided on a shaft of a motor providing driving force to the ball nut and disposed in parallel with the ball screw, and a middle gear coupled between the ball nut gear and the motor gear and transferring the driving force from the motor.