Linear Lift Actuator Failure Detection With Backup Nut Engagement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional lift devices relying on hydraulic cylinders require on-board reservoir tanks and are prone to actuator failures, which can lead to unsafe operating conditions and maintenance challenges.
Innovation Solution
A lift device equipped with a linear actuator comprising a central screw rod, primary and secondary nut mechanisms, and a lift controller that monitors lift characteristics to detect failures and engage a backup mechanism, eliminating the need for hydraulic systems and providing a failsafe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydraulic cylinders are used to control vertical movement, then lifting function is achieved, but the system requires on-board reservoir tanks and is prone to actuator failures
Solution Approach 1:
The patent replaces the hydraulic cylinder system with an electric linear actuator system. The linear actuator uses an electric motor to drive a screw rod and nut mechanism, converting rotational motion to linear motion for lifting the work platform. This substitution eliminates the need for hydraulic fluid, reservoir tanks, and associated hydraulic components, thereby reducing device complexity while improving reliability through simpler, more controllable electric actuation with integrated failure detection.
2Reliability
If a single nut mechanism is used in the linear actuator, then the structure is simple, but actuator failure cannot be detected or mitigated
Solution Approach 1:
The nut mechanism is segmented into two independent components: a primary nut mechanism for normal operation and a secondary nut mechanism for backup. The primary nut mechanism engages with the screw rod during standard lifting operations, while the secondary nut mechanism remains disengaged until needed. This segmentation allows the system to maintain simplicity during normal operation while providing failsafe capability through the redundant secondary mechanism.
Solution Approach 2:
The secondary nut mechanism is pre-positioned and prepared in advance but remains disengaged during normal operation. The lift controller is configured to detect when the primary nut mechanism fails and automatically engage the secondary nut mechanism with the screw rod. This preliminary preparation ensures that backup capability is immediately available without interfering with normal operation, achieving failsafe operation without continuous complexity.
3Duration of action of stationary object
If the secondary nut mechanism remains disengaged during normal operation, then friction and wear are minimized, but failure detection capability must be implemented
Solution Approach 1:
The lift controller implements feedback monitoring of the linear actuator's operation to detect primary nut mechanism failures. By continuously monitoring the actuator's performance parameters and comparing them against expected values, the controller can identify when the primary nut mechanism has failed and automatically engage the secondary nut mechanism. This feedback system enables failure detection without requiring the secondary mechanism to be engaged during normal operation, thereby preserving its service life while providing necessary monitoring 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
The solution enables safe and efficient operation by detecting actuator failures, preventing unsafe conditions, and reducing maintenance needs through electric actuation and a failsafe mechanism, eliminating the requirement for hydraulic systems.
Implementation Method 1
The electric motor is configured to provide rotational actuation to the central screw rod
Implementation Method 2
The primary nut mechanism is engaged with the central screw rod and configured to translate the rotational actuation of the central screw rod into translational motion
Data Source
AI summary
A lift device comprises a base, a retractable lift mechanism, a work platform, a linear actuator, and a lift controller. The base has a plurality of wheels. The retractable lift mechanism has a first end coupled to the base and is moveable between an extended position and a retracted position. The work platform is configured to support a load. The work platform is coupled to and supported by a second end of the retractable lift mechanism. The linear actuator is configured to selectively move the retractable lift mechanism between the extended position and the retracted position. The lift controller is configured to monitor at least one lift characteristic associated with the linear actuator and to determine whether an actuator failure has been detected based on the at least one lift characteristic associated with the linear actuator.