Linear Motor Lubricant Flow Control via Rotor Bypass
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Solution Overview
Problem
Linear actuators experience premature wear, vibration, and high friction due to the loss of lubrication between the leadscrew and lead nut, particularly at the limits of travel, leading to reduced performance and efficiency.
Innovation Solution
Incorporating a bypass channel within the rotor that allows excess lubricant to flow from a high pressure zone to a low pressure zone, reducing friction caused by lubricant viscosity, and utilizing a hollow rotor with an externally threaded leadscrew and internally threaded nut for efficient lubricant distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If lubricant is used to reduce wear between leadscrew and lead nut, then wear resistance is improved, but friction increases due to lubricant viscosity
Solution Approach 1:
The rotor is segmented into multiple chambers separated by partitions, with each chamber containing lubricant. This segmentation allows lubricant to be distributed to multiple locations simultaneously, ensuring continuous lubrication while reducing the total amount of lubricant needed, thereby balancing wear protection with friction reduction.
Solution Approach 2:
Lubricant pockets and bypass channels act as intermediaries between the leadscrew and lead nut, providing a controlled pathway for lubricant delivery. This intermediary system ensures lubricant reaches high-pressure zones without creating excessive friction, as the lubricant is delivered precisely where needed rather than being present throughout the entire mechanism.
2Reliability
If lubricant is distributed throughout the mechanism, then lubrication coverage is improved, but lubricant viscosity causes increased friction
Solution Approach 1:
Lubricant is delivered locally to specific high-pressure zones through bypass channels and pockets rather than being distributed uniformly throughout the mechanism. This local delivery ensures adequate lubrication coverage at critical interfaces while minimizing the presence of lubricant in areas where it would increase friction without providing benefit.
Solution Approach 2:
The lubricant delivery system is dynamic, with bypass channels that allow lubricant to flow to chambers based on operational conditions. The system adapts lubricant distribution to match the dynamic needs of the mechanism, providing lubrication where and when it is most needed while reducing friction in other areas.
3Force
If bypass channels are added to redistribute lubricant, then friction is reduced, but device complexity increases
Solution Approach 1:
The bypass channels and lubricant pockets are integrated into the rotor structure itself, merging the lubricant distribution function with the existing rotor component. This integration reduces the need for separate lubrication systems and minimizes overall structural complexity while still achieving friction reduction through effective lubricant redistribution.
Solution Approach 2:
The rotor serves multiple functions: it provides structural support, contains the lubricant chambers, and acts as the lubricant distribution system through its integrated bypass channels. This multi-functionality eliminates the need for separate lubrication components, reducing device complexity while maintaining friction reduction benefits.
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 bypass channel effectively reduces friction and wear by redistributing lubricant, enhancing the operational efficiency and longevity of the linear motor by maintaining consistent lubrication across the travel range.
Implementation Method 1
cause excess lubricant to flow from a high pressure zone to a low pressure zone through the passage
Implementation Method 2
reducing friction caused by the viscosity of the lubricant
Implementation Method 3
The rotor is surrounded by a rotor sleeve and extends along and is rotatable about a central axis
Data Source
AI summary
A linear motor includes a rotor rotatable relative to a surrounding rotor sleeve and about a central axis. At least one opening extends between an inner surface and an outer surface of the rotor. An externally threaded leadscrew extends through the rotor and along the central axis. An internally threaded nut is located within and mated to the rotor so as to rotate with the rotor about the central axis and ride along the leadscrew. A first cavity is located between the nut and a first bushing set against the inner surface of the rotor and a second cavity is located between nut and a second bushing set against the inner surface of the rotor. The at least one opening in the rotor forms a passage between the first and second cavities and is defined between the sleeve and nut so as to communicate excess lubricant.