Ballscrew Actuator Self-Lubrication Using an Internal Pump Piston
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Solution Overview
Problem
Ballscrew actuators require frequent manual replenishment of lubricant, which is costly and inefficient, as lubricant escapes through seals and needs regular re-injection to maintain minimal friction losses.
Innovation Solution
A ballscrew actuator design incorporating a lubrication piston and pump system that pressurizes air to move lubricant through lubrication passages, allowing for continuous lubricant supply during operation, reducing the need for manual replenishment by integrating a pump chamber, pumping piston, and non-return valves to manage air pressure and flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If manual lubricant replenishment is performed regularly, then the ballscrew actuator maintains minimal friction losses, but the maintenance cost and time increase
Solution Approach 1:
The system enables self-lubrication by using the ballscrew actuator's own operational movements to drive the pump piston, which automatically pressurizes and delivers lubricant to the interface. The actuator serves itself without external intervention, converting its mechanical motion into lubrication delivery.
Solution Approach 2:
The lubrication system is made dynamic by coupling the pump piston movement to the ballscrew actuator's operational cycles. The pump piston is positioned to be moved by the actuator during operation, creating a dynamic lubrication delivery mechanism that activates automatically during use rather than requiring static manual intervention.
2Reliability
If manual lubricant replenishment is performed regularly, then the lubricant interface remains properly lubricated, but the operational efficiency decreases
Solution Approach 1:
The system ensures continuous lubrication delivery by integrating the pump mechanism with the ballscrew actuator's operational cycles. Lubricant is continuously pressurized and delivered to the interface during operation, eliminating interruptions for manual replenishment and maintaining uninterrupted productive operation.
Solution Approach 2:
The actuator automatically performs its own lubrication needs by using its operational movements to drive the pump, eliminating the need for external maintenance intervention and maintaining continuous operational efficiency.
3Extent of automation
If a pump system is integrated into the ballscrew bore, then automated lubricant delivery is achieved, but the device complexity increases
Solution Approach 1:
The pump system is merged with the existing ballscrew bore structure, utilizing the available space and integrating the lubrication function into the actuator's existing architecture. This reduces the need for separate external lubrication systems and minimizes overall complexity.
Solution Approach 2:
The ballscrew actuator serves multiple functions: it performs its primary mechanical function while simultaneously driving the pump piston to deliver lubricant. The actuator's operational movements are dual-purpose, both accomplishing the mechanical task and enabling the lubrication function.
4Loss of time
If lubricant is continuously supplied, then manual replenishment frequency is reduced, but the system requires additional components
Solution Approach 1:
The system uses dynamic movement of the pump piston, driven by the ballscrew actuator's operational cycles, to continuously supply lubricant. This dynamic approach eliminates the need for complex reservoirs, pumps, and control systems that would be required for static continuous lubrication.
Solution Approach 2:
The system uses pneumatic pressure generated by the pump piston to deliver lubricant through passages to the interface. This pneumatic mechanism is simple and effective, using pressure differentials created during actuator operation to drive lubricant flow without requiring complex pumping machinery.
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 system ensures continuous lubrication of the ballscrew and ballnut interface, significantly reducing the frequency of manual lubricant replenishment, thereby extending the maintenance interval and maintaining operational efficiency.
Implementation Method 1
a pumping piston movable in a pumping direction for pressurising air in the pump chamber
Implementation Method 2
The pressurised air moves into the pressurising portion of the ballscrew bore through the outlet so as to move the lubrication piston therein, thereby to move lubricant through the lubrication passage
Implementation Method 3
Ballscrew actuators are lubricated in order to facilitate relative motion between a ballscrew, ballnut and balls
Data Source
AI summary
A ballscrew actuator comprises a ballnut having at least one first helical groove formed on a radially inner surface and defining an axis (X), a ballscrew disposed along the axis (X) within the ballnut, the ballscrew having at least one second helical groove formed on a radially outer surface and opposed to the first helical groove so as to form at least one helical raceway and a plurality of balls or rolling elements disposed in the at least one helical raceway. The ballscrew is movable relative to the ballnut between a stowed position and a deployed position. The ballscrew comprises a ballscrew bore extending axially therein. A lubrication piston is mounted for sliding movement within the ballscrew bore and divides the ballscrew bore axially into a lubricant receiving portion and a pressurising portion.