Lubricating Device for Rotating Nut Ball Screw Drive
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Solution Overview
Problem
Existing ball screw drives with a rotating nut face challenges in ensuring reliable lubrication to the rolling elements and spindle due to centrifugal forces, which can lead to inadequate lubrication and damage.
Innovation Solution
A lubricating device comprising an inner ring attached to the nut, an outer ring rotatably mounted on the inner ring, and a lubricant line that delivers lubricant directly to the spindle, utilizing pinions or an intermediate ring to distribute lubricant effectively, even at high speeds, and optionally using compressed air for enhanced lubrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the nut is set in rotation to increase dynamics, then the rotational moment of inertia is reduced, but centrifugal forces prevent reliable lubrication of the rolling elements and spindle
Solution Approach 1:
The patent introduces an intermediary lubrication system consisting of a lubricant reservoir and delivery mechanism that operates independently of the nut's rotation. This intermediary system delivers lubricant directly to the rolling elements and spindle through channels or nozzles, bypassing the centrifugal force problem caused by nut rotation. The lubricant is supplied under pressure or through gravity-fed channels that ensure consistent delivery regardless of the nut's rotational speed.
Solution Approach 2:
Instead of trying to overcome centrifugal forces by rotating the lubricant supply with the nut, the invention inverts the approach by making the lubricant supply system stationary or independently positioned. The lubricant is delivered from a fixed or separately mounted reservoir through channels that are not subject to the same centrifugal forces, effectively reversing the conventional approach where the lubricant source rotates with the nut.
2Ease of operation
If lubricant is supplied through a channel in a rotating adapter, then lubrication is provided, but centrifugal forces throw most lubricant outwards preventing it from reaching the spindle and rolling elements
Solution Approach 1:
The patent introduces a stationary or independently positioned lubricant reservoir and delivery system that acts as an intermediary between the lubricant source and the rolling elements. This intermediary system uses pressure-fed channels or gravity-driven pathways that are not subject to centrifugal forces, ensuring reliable lubricant delivery to the spindle and rolling elements regardless of nut rotation speed.
Solution Approach 2:
The invention employs hydraulic or pneumatic principles by using pressure-fed lubricant delivery systems. The lubricant is pumped under pressure through channels or nozzles that direct it precisely onto the rolling elements and spindle. This pressurized delivery method overcomes the centrifugal forces that would otherwise throw the lubricant outward, ensuring effective lubrication even at high rotational speeds.
3Reliability
If the inner ring penetrates the interior space axially to enable robust mounting, then mounting reliability is improved, but lubricant distribution paths become more complex
Solution Approach 1:
The patent applies segmentation by dividing the lubricant delivery system into distinct functional segments: a lubricant reservoir, delivery channels or nozzles, and distribution points at the rolling element interfaces. The inner ring's axial penetration creates separate zones for mounting and lubrication, with dedicated channels that segment the lubricant flow paths. This segmentation allows for robust mounting while maintaining relatively simple, dedicated lubricant delivery routes for each section.
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
Ensures reliable and consistent lubrication of the spindle and rolling elements, preventing damage and maintaining the performance and longevity of the ball screw drive, even at high speeds and dynamic conditions.
Implementation Method 1
Due to the centrifugal forces, a large part of the lubricant is thrown outwards and does not get onto the spindle and the rolling elements.
Data Source
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AI summary
A lubrication device is proposed that enables a reliable supply of lubricant to the ball screw drive, even in ball screw drives with a stationary threaded spindle 3 and a rotating nut 1. A shoulder 48 for receiving the intermediate ring 47 is formed in the bearing seat 11 of the inner ring 5.