Open Ball Screw Nut Structure for Holder Clearance and Smooth Rolling

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Solution Overview

Problem

Conventional ball screw assemblies with complete cylinder ball nuts face issues of sagging and deflection due to additional resilient mechanisms, leading to manufacturing precision problems and improper ball rolling, especially when a supporting holder is present.

Innovation Solution

A ball screw assembly with an open nut featuring an axial opening, allowing it to pass supporting holders without interference, eliminating the need for resilient mechanisms and maintaining guider stability, while also forming a dustproof outer ball race for improved performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a complete cylinder ball nut is used with a supporting holder, then the screw can be supported to prevent sagging, but the ball nut cannot pass the supporting holder without interference, requiring additional resilient mechanisms

Engineering Contradiction:
Improvesupporting holder stabilityVSAvoidresilient mechanism complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The ball nut is designed with an axial opening that segments the cylindrical structure, allowing the supporting holder to pass through the ball nut without interference. This segmentation eliminates the need for resilient mechanisms while maintaining supporting holder stability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The resilient mechanism is extracted/removed from the system entirely. The axial opening design allows the supporting holder to pass through directly without requiring any resilient mechanism, simplifying the overall device structure.

Inventive Principle:
Principle #2Taking out (Extraction)

2Ease of operation

If a resilient mechanism is added to the supporting holder, then the supporting holder can move away from the screw during ball nut passage, but the screw may sag due to its weight when the supporting holder is away, causing deflection and improper ball rolling

Engineering Contradiction:
Improveball nut passage smoothnessVSAvoidscrew deflection
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The axial opening segments the ball nut structure, enabling the supporting holder to pass through continuously without detaching. This ensures the screw remains supported at all times, preventing sagging and maintaining manufacturing precision during ball nut passage.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The axial opening acts as an intermediary structure that facilitates the passage of the supporting holder through the ball nut. This design allows continuous support of the screw while enabling smooth passage, eliminating the need for resilient mechanisms that cause sagging.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Adaptability or versatility

If additional resilient mechanisms are configured at the supporting holders, then the ball nut can pass the supporting holder, but the device complexity increases and manufacturing precision becomes compromised

Engineering Contradiction:
Improveball nut passage capabilityVSAvoidresilient mechanism structure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The axial opening segments the ball nut into a structure that allows the supporting holder to pass through. This simple segmentation provides the required adaptability for ball nut passage without adding complex resilient mechanisms, thereby reducing overall device complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The resilient mechanism is completely removed from the system. The axial opening design inherently provides the passage capability without requiring any additional resilient components, simplifying the device structure while maintaining adaptability.

Inventive Principle:
Principle #2Taking out (Extraction)

4Ease of operation

If the supporting holder is positioned away from the screw during ball nut passage, then the ball nut can pass, but the screw encounters deflection and balls cannot roll properly in the spiral groove

Engineering Contradiction:
Improveball nut passageVSAvoidball rolling function
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The axial opening segments the ball nut structure to allow continuous passage of the supporting holder through the ball nut. This ensures the screw remains continuously supported, preventing deflection and maintaining proper ball rolling function throughout the passage process.

Inventive Principle:
Principle #1Segmentation

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 design enhances manufacturing precision and prevents sagging or deformation of the guider, ensuring smooth ball rolling and improved operational performance by eliminating the need for additional resilient mechanisms and providing a dustproof function.

Implementation Method 1

the friction between the ball nut and the screw can be reduced during the operation

Methodology Applied
Scientific EffectFriction reduction through ball rolling: Ball Bearing

Implementation Method 2

The ball screw assembly comprises a guider, an open nut, an open shield, a first circulator, a second circulator, and a ball circulating assembly

Methodology Applied
Scientific EffectScrew mechanism: Screw

Data Source

PatentEP3828438B1Ball screw assembly
Publication Date: 2022.04.20 LEE SZU YING
  • EP3828438B1 patent drawingFigure 1
  • EP3828438B1 patent drawingFigure 2
  • EP3828438B1 patent drawingFigure 3

AI summary

A ball screw assembly includes a guider (10), an open nut (20), an open shield (30), a first circulator (40), a second circulator (50), and a ball circulating assembly (60). The open nut (20) is slidably fitted over the guider (10) and includes an axial cylinder (21) having an axial opening (211). An inner spiral channel (2141) of the axial cylinder (21) and a spiral channel (11) of the guider (10) form an inner ball race. The open shield (30) is coaxially fitted over the axial cylinder (21). An inner peripheral wall (31) of the open shield (30) and an outer annular wall (215) of the axial cylinder (21) form an outer ball race. The first circulator (40) and the second circulator (50) are disposed on the axial cylinder (21). The inner ball race, a first curve (41) of the first circulator (40), the outer ball race, and a second curve (51) of the second circulator (50) form a ball circulating race, and the ball circulating assembly (60) rolls in the ball circulating race.