Rolling-Element Bearing Lubricant Loop to Prevent Stagnation
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Solution Overview
Problem
Existing rolling-element bearings in turbomachines, such as those used in aircraft, rely on external lubrication systems that degrade engine performance and increase costs due to inefficiencies in lubricant recirculation, leading to lubricant stagnation in dead areas.
Innovation Solution
A self-lubricated rolling-element bearing with an internal loop circuit for forced lubricant recirculation, where rolling elements roll over orifices that act as inlets and outlets, creating a pump effect to circulate lubricant without external pumping means, utilizing centrifugal force to prevent stagnation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an external lubrication system with pump is used, then lubrication can be ensured, but device complexity and mass increase
Solution Approach 1:
The patent extracts the pumping function from the external lubrication system and relocates it to the bearing itself through the rolling elements. The bearing now contains an integrated recirculation circuit with inlets and outlets that allow lubricant to be pumped internally by the rolling elements passing over the orifices, eliminating the need for external pumps and complex lubrication systems.
Solution Approach 2:
The bearing becomes self-sufficient by using its own rolling elements to pump and recirculate the lubricant through internal circuits. The rolling elements automatically perform the dual function of supporting loads and pumping lubricant, making the system self-service and eliminating external lubrication infrastructure.
2Reliability
If external pumping means are used, then lubricant recirculation is achieved, but operating cost and energy consumption increase
Solution Approach 1:
The bearing uses its own operational motion (rolling elements rotating) to pump the lubricant without requiring external energy input. The kinetic energy already present in the rotating bearing is converted into pumping action, making the system energy-efficient and eliminating continuous external power requirements for lubrication.
Solution Approach 2:
The lubrication system transitions from a static external pump to a dynamic internal system where the rolling elements continuously pump lubricant during rotation. This dynamic approach converts the bearing's rotational motion into effective lubricant circulation, eliminating the need for separate powered pumping mechanisms.
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
This solution reduces the number of components, operating and manufacturing costs, and mass of the turbomachine by eliminating the need for external pumping systems, ensuring reliable and efficient lubrication by preventing lubricant stagnation through self-sustaining recirculation.
Implementation Method 1
This configuration has the advantage of generating a recirculation of the lubricant by pump effect. This pump effect is achieved by the fact that the circuit opens directly onto at least one of the raceways. The rolling-elements roll over the outlets of the circuit and force the lubricant in the raceway to be injected into the or each lubricant inlet.
Implementation Method 2
The invention allows to usefully take advantage of the centrifugal force, which in the bearings of the self-lubricated type of the prior art tends to throw the lubricant towards dead areas of the external portion of the bearing which does not rotate, the lubricant remaining trapped in these dead areas in which it stagnates. The higher the speed of rotation of the internal portion of the bearing, the greater the centrifugal force.
Data Source
AI summary
Rolling-element bearing for a turbomachine of an aircraft, comprising an inner ring (3) defining a first raceway (112), and an outer ring (4) defining a second raceway (124), characterized in that the bearing has at least one loop circuit (21, 22) for forced recirculation of lubricant, this loop circuit comprising a first recirculation circuit (21) comprising at least one lubricant inlet (1200) located on the second raceway (124), and connected by at least one duct (120, 166) created in the outer ring (4) to at least one lubricant outlet (1661) which discharges into a second recirculation circuit (22) of the loop circuit (21, 22), this second recirculation circuit (22) comprising at least one duct (152, 1134, 1136; 1135, 1136) created in the inner ring (3).