Vacuum Pump Rotor Shaft Recesses for Lubricant Containment
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Solution Overview
Problem
Lubricant migration from ball bearings into the active pumping area of vacuum pumps, particularly when the rotor shaft is vertically aligned, is a challenge due to oil dripping onto the rotor shaft and being drawn into the vacuum pump during operation or positional changes.
Innovation Solution
The rotor shaft features recesses on its outer surface, inclined relative to the radial direction, creating additional volume to collect and contain lubricant, preventing it from migrating into the pump's active elements by directing it back to the bearing area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a ball bearing is used to support the rotor shaft in a vacuum pump with vertical rotor shaft alignment, then the rotor shaft can be supported cost-effectively, but lubricant can migrate from the ball bearing into the active pumping area
Solution Approach 1:
The harmful lubricant is extracted from the path leading to the active pumping area by creating a dedicated recess in the rotor shaft that collects and isolates the lubricant, preventing its migration into the vacuum pump's active elements
Solution Approach 2:
A return felt is introduced as an intermediary element between the rotor shaft surface and the active pumping area. This felt captures lubricant that escapes the recess and returns it to the bearing area through capillary action, serving as a protective barrier
2Adaptability or versatility
If the vacuum pump is operated with the rotor's axis of rotation aligned vertically, then installation flexibility is improved, but lubricant can drip from the ball bearing onto the rotor shaft and be drawn into the pumping system
Solution Approach 1:
The recess is pre-formed in the rotor shaft at a location that anticipates lubricant accumulation when the pump operates in vertical orientation. This preliminary structural preparation ensures that lubricant is captured before it can migrate to harmful areas, enabling reliable vertical operation
Solution Approach 2:
The rotor shaft is given a different local quality at the bearing area through the recess, which specifically addresses the lubricant management problem in that localized region while allowing the rest of the shaft to maintain its standard design for various orientations
3Reliability
If oil is returned to the ball bearing using return felts during operation, then lubricant migration is controlled during rotation, but oil that drips during shutdown cannot be effectively managed when the pump is restarted or repositioned
Solution Approach 1:
The recess provides a preliminary collection point for lubricant during shutdown, preventing it from spreading onto the rotor shaft surface before the pump is restarted or repositioned. This preliminary containment is crucial for preventing migration in subsequent operations
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
Prevents or significantly reduces lubricant migration into the vacuum pump's active elements, ensuring reliable operation and flexibility in installation orientations.
Implementation Method 1
the oil is thrown from the flat surface of the rotor shaft against such a return felt and is returned to the ball bearing by its capillary action
Data Source
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AI summary
A vacuum pump has a rotor shaft that carries pump-active elements of a rotor of the vacuum pump, and at least one bearing on which the rotor shaft is rotatably mounted. A lubricant is provided for lubricating the bearing. The rotor shaft has at least one recess, located outside a bearing area of the rotor shaft, designed to receive the lubricant.