Sliding Piston Helical Grooves for Hydrodynamic Actuator Bearings
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Solution Overview
Problem
Existing electromechanical actuators face challenges with friction between the sliding piston and the spindle, leading to energy wastage, frictional heat, and wear, especially when the cantilever is rapidly retracted and extended, resulting in differential pressure and reduced efficiency.
Innovation Solution
A linear actuator design featuring a sliding piston with optimized geometry and material selection, including helical grooves for fluid flow and a wrought aluminum alloy with high silicon content, to prevent piston rotation and enhance hydrodynamic lubrication, thereby minimizing friction and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a sliding piston is used between the cantilever and threaded spindle, then the actuator can achieve linear motion through fluid pressure, but friction between the sliding piston and spindle causes energy loss, heat generation, and wear
Solution Approach 1:
The patent applies hydrodynamic lubrication by introducing a fluid medium between the sliding piston and threaded spindle. The fluid forms a lubricating film that separates the sliding surfaces, replacing direct solid-to-solid contact with fluid-mediated contact. This hydraulic approach reduces friction and wear while maintaining the linear motion function of the sliding piston.
2Speed
If the cantilever is rapidly retracted and extended, then the actuator responds quickly to control signals, but differential pressure builds up inside the actuator increasing idle torque and reducing efficiency
Solution Approach 1:
The patent segments the fluid flow path by introducing channels through the threaded spindle and nut. This segmentation creates multiple flow routes that allow fluid to bypass high-pressure zones during rapid cantilever movement. The divided flow paths reduce pressure buildup and enable smoother fluid circulation, decreasing idle torque while maintaining rapid response capability.
3Loss of energy
If the interior is filled with lubricating oil for lubrication, then friction is reduced, but the incompressible nature of the fluid creates strong differential pressure during rapid cantilever movement
Solution Approach 1:
The patent applies local quality by creating different fluid permeability zones. The sliding piston has sealed regions for maintaining lubrication pressure where needed, while specific channels and passages are provided in the threaded spindle and nut to allow fluid bypass in high-pressure zones. This localized differentiation of fluid flow characteristics reduces overall differential pressure during rapid movement while preserving lubrication effectiveness at critical interfaces.
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 effectively reduces friction and wear, stabilizes lubrication across a wide temperature range, and improves the efficiency of the actuator by ensuring smooth fluid flow and preventing differential pressure issues.
Implementation Method 1
a sliding bearing flows between the sliding piston and the threaded spindle in this flow
Implementation Method 2
the liquid can pass through the threaded nut upon movement of the cantilever, wherein a first longitudinal channel is located inside the threaded spindle
Data Source
AI summary
An electromechanical linear actuator includes, among other things, a sliding piston with helical grooves for a floating bearing of a spindle in an electromechanical actuator. With relative movement of the spindle with respect to the sliding piston, a lubrication fluid passing through the grooves between the sliding piston and the spindle may assist in hydrodynamic lubrication between these two parts.