EPS Steering Shaft Joint Structure for Low-Temperature Noise Reduction
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Solution Overview
Problem
Conventional EPS devices face high production costs, weight, and packaging challenges, and generate noise and vibration at low temperatures due to the use of needle bearings.
Innovation Solution
A steering shaft connecting structure that combines a copper bush and needle bearings, where the copper bush contacts the needle bearings at high temperatures to increase frictional force and support weight, while only needle bearings support at room temperature, reducing noise and vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If needle bearings are used to support weight and reduce friction, then production cost and weight are reduced, but noise and vibration increase at low temperatures
Solution Approach 1:
The support structure is segmented into two distinct components: needle bearings for weight support and friction reduction, and copper bushes for noise and vibration damping. This segmentation allows each component to specialize in its optimal function, with the copper bushes specifically addressing the noise issue that needle bearings cannot resolve.
Solution Approach 2:
The invention uses a composite support structure combining metal needle bearings with copper bushes. This composite approach leverages the high strength-to-weight ratio and low friction properties of needle bearings while utilizing the superior damping characteristics of copper to suppress noise and vibration at low temperatures.
2Reliability
If three bearings are used to support weight, then reliability is improved, but production cost and weight increase
Solution Approach 1:
The invention merges the weight support function and the noise damping function into a single integrated structure. The needle bearings and copper bushes work together as a unified support system, eliminating the need for separate damping components and reducing the total bearing count from three to two while maintaining or improving overall reliability.
Solution Approach 2:
The combined needle bearing-copper bush structure serves multiple functions simultaneously: weight support, friction reduction, and noise/vibration damping. This multi-functionality replaces the need for three specialized bearings with a more efficient two-component system that handles all support requirements.
3Object-generated harmful factors
If copper bush is used between shafts, then noise is reduced, but weight and device complexity increase
Solution Approach 1:
The copper bushes serve as intermediary elements positioned between the input and output shafts. These intermediaries provide noise damping through their material properties while maintaining the functional relationship between shafts, achieving noise reduction without requiring substantial additional weight.
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 structure effectively reduces production costs, weight, and facilitates packaging while minimizing noise and vibration at low temperatures by leveraging thermal contraction of the copper bush to enhance frictional force.
Implementation Method 1
the copper bush may thermally contract at a low temperature so that the rotational frictional force may increase
Data Source
AI summary
A structure of an electric power steering device in which its steering shafts are connected includes a torsion bar connected to a steering wheel; an input shaft surrounding the torsion bar on an input side of the torsion bar; and an output shaft surrounding one end of the input shaft and the torsion bar on an output side of the torsion bar, wherein the one end of the input shaft is inserted into and coupled to one end of the output shaft, and a copper bush and a needle bearing are disposed side by side between an outer circumferential surface of the one end of the input shaft and an inner circumferential surface of the one end of the output shaft.