Ball Screw Lubrication Circuit With Shuttle-Driven Recirculation
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Solution Overview
Problem
Existing ball screw assemblies require frequent lubrication due to the presence of dead volumes that do not effectively distribute lubricant, leading to increased friction and wear.
Innovation Solution
A re-circulating lubricant flow path is introduced within the ball screw assembly, utilizing a lubricant channel and chamber system that directs lubricant flow through a shuttle mechanism, minimizing dead volumes and enhancing lubrication efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional lubrication method is used with dead volumes, then lubricant can be introduced into the ball screw assembly, but lubrication distribution is ineffective and friction increases
Solution Approach 1:
The patent removes dead volumes from the lubrication system by extracting them through strategically placed lubricant channels that connect to ball return channels. This eliminates the harmful stagnant zones where lubricant would otherwise accumulate without providing effective lubrication, thereby resolving the contradiction between introducing lubricant and achieving effective lubrication distribution.
Solution Approach 2:
The patent introduces lubricant channels as intermediary structures that mediate between the lubricant introduction point and the ball bearing contact zones. These channels serve as conduits to transport lubricant effectively to areas of high friction, resolving the contradiction by creating a controlled pathway that ensures lubrication reaches where it is needed most.
2Reliability
If frequent lubrication servicing is performed, then friction and wear are reduced, but maintenance time and operational interruption increase
Solution Approach 1:
The patent incorporates a lubricant reservoir that pre-stores lubricant and provides a controlled release mechanism. This preliminary action ensures lubricant is available when needed without requiring frequent external servicing, thereby reducing wear while minimizing maintenance time and operational interruptions.
Solution Approach 2:
The patent creates a continuous lubrication circuit where lubricant flows continuously through the load circuit and ball return channels. This continuous action ensures constant lubrication protection against wear without requiring periodic interruption for manual re-lubrication, thus reducing wear while minimizing servicing time.
3Duration of action of moving object
If dead volumes are present in the lubrication system, then lubricant can be stored, but lubrication distribution becomes inconsistent and service life decreases
Solution Approach 1:
The patent segments the lubrication system into distinct functional zones: load circuits for ball bearing travel, ball return channels for ball recirculation, and lubricant channels for lubricant transport. This segmentation eliminates dead volumes by ensuring each segment has a clear flow path, thereby achieving consistent lubrication distribution that extends service life.
Solution Approach 2:
The patent employs hydraulic principles by creating a closed-loop lubrication circuit where lubricant flows continuously under pressure through defined channels. This hydraulic approach eliminates stagnant dead volumes and ensures consistent lubricant distribution throughout the system, thereby extending service life through reliable and uniform lubrication.
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 solution extends lubricant intervals between servicing, reduces friction, and improves the service life of ball screw assemblies by ensuring consistent lubrication distribution.
Implementation Method 1
The shuttle is engaged with the longitudinally extending surface of the screw shaft and is in sliding contact with the ball nut. Rotation of one of the screw shaft and the ball nut relative to the other around the longitudinal axis causes the shuttle to impel lubricant along the lubricant channel.
Data Source
Figure 1~2
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AI summary
A ball screw (2) comprising a screw shaft (4), a ball nut (6), and a load circuit (23) is disclosed. The load circuit comprises a first and second part (23A, 23B). The screw shaft is longitudinally extending with a longitudinal central axis (A) and at least part of the longitudinally extending surface of the screw shaft comprises an external thread (8). The first part (23A) of the load circuit comprises a part of the external thread (8). The ball nut comprises a body (10), a bore (12), and the second part (23B) of the load circuit, and a lubricant channel (26),. The bore is defined by the body, is longitudinally extending with a longitudinal central axis, has a first and second end (17, 18), and has a longitudinally extending surface (19) extending at least partially between the first and second ends. The first and second ends of the bore each comprise a mouth, and each mouth opens through an outside surface of the body. The longitudinally extending surface of the bore comprises an internal thread (20), and the first part of the load circuit comprises at least a part of the internal thread. The screw shaft extends through the bore of the ball nut and the screw shaft and bore are so configured that they are co-axial, the external thread and internal thread are so configured that the external thread and the internal thread together define the first part of the load circuit. The first part of the load circuit extends an axial distance along the bore and at least part of the second part of the load circuit extends through the ball nut. The lubricant channel comprises a first and a second channel end (27, 28) and a flow path (29) between the first and second channel ends. Rotation around the longitudinal axis of one of the screw shaft and the ball nut relative to the other causes axial movement of the ball nut relative to the screw shaft. The ball screw further comprises a shuttle (11). The shuttle is engaged with the longitudinally extending surface of the screw shaft, and the shuttle is in sliding contact with the ball nut. Rotation of one of the screw shaft and the ball nut relative to the other around the longitudinal axis causes the shuttle to impel lubricant through the lubricant channel.