Lead Screw Nut Compensation for Thread Abrasion Noise
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Solution Overview
Problem
The existing lead screw structures in electric steering apparatuses for vehicles suffer from thread surface abrasion, leading to gaps between coupling faces, which result in noise and inefficient transmission of driving force.
Innovation Solution
A lead screw structure incorporating a screw shaft with an outer thread and a nut unit with an inner thread, where a first elastic member, such as a wave washer, is used to provide an elastic force that compensates for the gap caused by thread surface abrasion, ensuring proper engagement and force transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a lead screw structure with thread surfaces is used to convert rotational force to linear driving force, then the driving function is achieved, but the thread surfaces are easily abraded causing gaps between coupling faces
Solution Approach 1:
A resin layer is introduced as an intermediary substance between the male screw shaft and female screw nut member. This resin layer prevents direct metal-to-metal contact, reducing abrasion while maintaining the thread engagement function for force transmission
Solution Approach 2:
The patent uses a composite structure combining metal threads with a resin coating. The metal provides structural strength and threading, while the resin provides wear resistance and smooth operation, creating a composite thread surface that addresses both durability and functional requirements
2Productivity
If the screw shaft and nut member are mechanically engaged with thread surfaces, then rotational to linear motion conversion is achieved, but noise is generated when gaps form due to abrasion
Solution Approach 1:
The resin layer acts as a mediator that eliminates direct metal contact and gap formation, thereby preventing the knocking and noise that occur when abraded thread surfaces create clearance
Solution Approach 2:
The resin coating forms a thin film layer on the thread surfaces that maintains continuous contact between mating threads, eliminating the gaps that cause noise while allowing the underlying metal structure to maintain its mechanical strength
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 elastic member effectively compensates for the gap between the screw shaft and nut surfaces, reducing noise and maintaining efficient power transmission even after thread surface abrasion, thereby enhancing the reliability and performance of the steering apparatus.
Implementation Method 1
a first elastic member disposed on a portion of the nut portion, in a direction of the screw shaft, to provide an elastic force to the nut portion in the screw shaft
Data Source
AI summary
A lead screw structure comprises a screw shaft having a thread on an outer circumferential surface thereof, a nut unit coupled to the screw shaft such that and a thread formed on an inner circumferential surface of the nut unit is engaged with the thread of the screw shaft, and a first elastic member disposed on a portion of the nut portion, in a direction of the screw shaft, to provide an elastic force to the nut portion in the screw shaft, thereby compensating for a gap between the thread of the outer circumferential surface of the screw shaft and the thread of the inner circumferential surface of the nut unit.