Pressure-Relieved Linear Actuator for Threaded Drive Protection
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Solution Overview
Problem
Existing linear actuators with threaded drives face challenges such as damage from axial impacts and insufficient lubrication due to high axial forces, which complicates the design and functionality, especially when combined with electrical and hydraulic systems.
Innovation Solution
The linear actuator incorporates a first region of the internal space connected to a pressure accumulator to generate relief pressure, which acts axially on the leadscrew and piston, enhancing the resilience of the threaded drive against external forces. Additionally, an annular fluid space can be pressurized to further relieve the threaded drive.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the second region is surrounded by the housing in multiple positions of the cantilever tube, then the linear actuator can maintain pressure in the second region, but the design complexity increases significantly due to the need for a valve with flow connection from the movable cantilever tube to the fixed housing
Solution Approach 1:
The internal space is divided into two fluidically sealed regions by a piston: a first region connected to the housing and a second region surrounding the leadscrew. This segmentation allows the first region to maintain pressure through simple housing connection while the second region maintains pressure through the compressible gas and piston seal, eliminating the need for complex valves.
Solution Approach 2:
The piston acts as an intermediary element that fluidically seals the two regions. It prevents lubricating oil from the second region from leaking into the first region while allowing independent pressure maintenance in each region, simplifying the overall pressure control system.
2Reliability
If axial impacts or high axial forces are applied to the linear actuator, then the threaded drive may be damaged or lubricating oil may be pushed away from contact surfaces, but the invention uses a compressible gas in the second region to compensate for volume changes and maintain lubrication
Solution Approach 1:
The compressible gas in the second region serves as a cushion that absorbs axial impacts and high axial forces before they can damage the threaded drive or push lubricating oil away from contact surfaces. The gas compressibility provides inherent shock absorption and pressure regulation.
Solution Approach 2:
The use of compressible gas in the second region leverages pneumatic principles to provide shock absorption and pressure compensation. The gas acts as a pneumatic cushion that maintains constant pressure on the lubricating oil, ensuring continuous lubrication of the threaded drive even under axial loads.
3Adaptability or versatility
If the linear actuator is designed with separate electric and hydraulic cylinders, then each actuator can be independently controlled, but a large design space is necessary and transverse forces arise between the linear actuators
Solution Approach 1:
The invention merges the electric motor-driven leadscrew mechanism with the hydraulic pressure system into a single integrated linear actuator. The electric motor rotates the leadscrew to move the threaded nut and cantilever tube, while the hydraulic pressure in the first region provides axial support and shock absorption, eliminating the need for separate electric and hydraulic cylinders.
Solution Approach 2:
The first region connected to the housing serves multiple functions: it provides hydraulic pressure support, absorbs axial impacts, and stabilizes the threaded drive. This multi-functional design replaces what would otherwise require separate dedicated components, reducing the overall design space and component count.
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 effectively reduces the risk of damage to the threaded drive from axial impacts and ensures consistent lubrication, allowing the linear actuator to withstand higher external forces without compromising performance.
Implementation Method 1
the first region of the internal space of the cantilever tube being connected to a first pressure source, in particular a pressure accumulator, in order to be able to generate a certain relief pressure in the first region by means of the first pressure source
Implementation Method 2
The piston divides an internal space formed by means of the cantilever tube into two regions, the first being formed on the side of the piston opposite the threaded nut and the second being formed on the side of the piston facing the threaded nut such that the first and second regions are separated from one another in a fluidically sealed manner
Implementation Method 3
A lubricating oil is arranged in the second region in order to lubricate and/or cool the leadscrew
Data Source
AI summary
A linear actuator having a threaded drive including a nut connected to a cantilever tube and a leadscrew coupled to a motor, so that, by rotation of the leadscrew, the threaded nut and the cantilever tube are linearly movable, and, regardless of the position of the cantilever tube, one end the leadscrew projects into the cantilever tube and is connected to a piston which divides an internal space formed by the cantilever tube into a first region on the side of the piston opposite the threaded nut and a second region on the side of the piston facing the nut. The two regions are separated from one another in a fluidically sealed manner. A relief of the threaded drive is improved since the first region is connected to a pressure accumulator to generate a relief pressure in the first region using the first pressure source.