Ball Nut Support Structure for Low-Noise Rack-Driven Steering
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Solution Overview
Problem
Conventional rack-driven power assisted steering apparatuses suffer from low noise performance due to single-row bearing support for the ball nut, leading to ineffective load absorption, increased component count, and complex assembly.
Innovation Solution
A rack-driven power assisted steering apparatus with rolling members arranged in double rows, supported by a ball nut assembly coupled to a housing via an elastic member, reducing the number of components and simplifying assembly by direct support of rolling members on the ball nut or support members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-row bearing is used to support the ball nut, then the device complexity is reduced, but the noise performance deteriorates due to ineffective load absorption
Solution Approach 1:
The patent transitions from a single-row bearing configuration to a double-row bearing configuration, adding a dimensional aspect to the support structure. This double-row arrangement provides load absorption in multiple directions, effectively reducing noise while maintaining reasonable device complexity through the systematic arrangement of rolling members.
Solution Approach 2:
The patent combines multiple rolling members into a unified double-row bearing structure that supports the ball nut assembly. By merging the support functions into an integrated double-row configuration, the system achieves better load distribution and noise reduction without proportionally increasing component count.
2Object-affected harmful factors
If a double-row bearing is used to support the ball nut, then the noise performance is improved through effective load absorption, but the number of components increases
Solution Approach 1:
The double-row bearing is segmented into two distinct rows of rolling members, each row independently supporting loads in different directions. This segmentation allows for optimized load distribution while keeping the overall structure compact, reducing the need for additional separate components.
Solution Approach 2:
The double-row bearing structure serves multiple functions simultaneously: it supports radial loads, axial loads, and moment loads, while also providing noise reduction. This multi-functionality reduces the need for separate dedicated components for each function, thereby limiting the increase in total component count.
3Object-affected harmful factors
If a double-row bearing is used to support the ball nut, then the noise performance is improved, but the assembling process becomes more complicated
Solution Approach 1:
The double-row bearing is designed as an integrated assembly where the two rows of rolling members are pre-positioned and secured within a common bearing structure. This merging of the double-row configuration into a single manufacturable unit simplifies the assembly process, as the entire double-row bearing can be installed as one component rather than assembling multiple separate bearing elements.
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
Improves noise performance by effectively absorbing ball nut movement with double-row rolling members and reduces component count and assembly complexity.
Implementation Method 1
a ball nut assembly coupled to a housing via an elastic member
Data Source
AI summary
According to the present embodiments, provided is a rack-driven power assisted steering device in which a rolling member supporting the rotation of a ball nut is provided in a double row, a ball nut assembly is coupled to a housing through an elastic member, the flow of the ball nut is absorbed to improve noise performance, and the rolling member is directly supported by the ball nut or a support member, so that the number of parts can be reduced and easy assembly is possible.