Linear Actuator with Serrated Planetary Roller Holder
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Solution Overview
Problem
Existing electric actuators with reversible screw mechanisms and satellite rollers face inefficiencies when attempting to make the system irreversible, as conventional irreversible solutions compromise performance.
Innovation Solution
An electric actuator with a serrated planetary roller holder and a two-position linear electric motor that selectively blocks synchronous rotational movement, allowing the system to be irreversibly locked in any position without affecting normal operation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional screw/nut system is used to make the mechanism irreversible, then the irreversibility is achieved, but the performance becomes poor
Solution Approach 1:
The planetary roller holder is designed to be dynamically switchable between two states: engaged (blocking axial movement) and disengaged (allowing axial movement). This dynamic capability allows the system to transition between irreversible and reversible operation modes, resolving the contradiction by making irreversibility conditional rather than permanent.
Solution Approach 2:
The system changes the operational parameter of the planetary roller holder from a fixed state to a variable state controlled by the two-position linear electric motor. By changing the position parameter of the holder (engaged/disengaged), the system achieves irreversibility only when needed, maintaining high performance when reversibility is required.
2Stability of the object's composition
If the mechanism is made irreversible to immobilize the screw in any position, then position holding capability is improved, but the ability to move axially under external forces is reduced
Solution Approach 1:
The planetary roller holder's engagement state is dynamically controlled, allowing the system to switch between position-holding mode (engaged) and movement mode (disengaged). This dynamic control resolves the contradiction by making the position holding capability adjustable rather than fixed.
Solution Approach 2:
The two-position linear electric motor automatically controls the planetary roller holder engagement based on system requirements, enabling the mechanism to self-regulate between irreversible and reversible states without external intervention, thus maintaining both position stability and movement capability as needed.
3Reliability
If a two-position linear electric motor is used to control the planetary roller holder, then the system complexity increases, but the ability to selectively block movement is improved
Solution Approach 1:
The complex control function is extracted into a dedicated two-position linear electric motor that specifically controls the planetary roller holder engagement. This separation of functions allows the main actuator to focus on its primary function while the linear motor handles the blocking control, managing overall system complexity through functional decomposition.
Solution Approach 2:
The two-position linear electric motor serves multiple functions: it controls the planetary roller holder engagement, detects system position through inductance measurement, and provides a reference for the axial position of the threaded linear rod. This multi-functionality reduces the need for additional separate components, managing complexity while enhancing capability.
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
Enables the actuator to maintain position without power and reduce axial movement under external forces, maintaining efficiency while allowing reversible operation when needed.
Implementation Method 1
a two-position linear electric motor comprising a stator formed of a first and a second annular windings axially separated by a determined distance and a rotor formed by a concentric shaft carrying a first and a second adjacent permanent magnet annular segment
Implementation Method 2
the axial and radial guidance of said rotor shaft is achieved by a carbon bearing mounted between said rotor shaft and said annular windings
Implementation Method 3
held in position against spring washers by a force adjustment nut
Data Source
Figure 1
Figure 2
AI summary
The actuator (10) has an electric motor (14) with a tubular rotor (18) carrying segments of permanent magnet (20) and constituting a screw nut of screw mechanism and satellite rollers (34). The rollers are mounted on a satellite roller holder (32). The holder has a serration cooperating with a corresponding serration of selection mechanism (40) actuated by a linear electric motor (42) for preventing the axial translational movement of threaded linear rod (30) under the action of outer traction or compression force by selectively blocking synchronous rotational movement of the rollers.