Lifting Device Torque Limiter for Manual Load Positioning
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Solution Overview
Problem
Conventional hoists struggle with precise and sensitive positioning of heavy loads due to increased inertial forces, limiting their application range, and motor-driven hoists often fail to provide precise control.
Innovation Solution
A hoist with a support drive and control device integrated near the load, featuring a torque limiter like a slipping clutch, allows manual control and correction while providing motor-assisted acceleration and deceleration, enabling precise positioning of loads over 100 kg without losing manual precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If motor-driven hoists are used to handle heavy loads, then the load capacity is improved, but the positioning precision and sensitivity deteriorate
Solution Approach 1:
A support drive acts as an intermediary between the manual operator and the heavy load. The support drive provides motor assistance to overcome high inertial forces during acceleration and deceleration, while the torque limiter ensures the manual operator retains direct control for precise positioning. This intermediary system enables both heavy load handling and precise positioning by mediating between manual input and motor power.
2Force
If conventional cranes or motor-driven hoists are used for heavy loads, then the lifting capacity is improved, but the manual control and sensitivity are lost
Solution Approach 1:
The support drive dynamically adjusts its level of assistance based on operational needs. During acceleration and deceleration phases, the motor provides high torque to overcome inertial forces. During positioning phases, the torque limiter engages to reduce motor intervention, allowing direct manual control. This dynamic behavior enables the system to adapt between power-assisted and manual control modes as needed.
Solution Approach 2:
The torque limiter changes the transmission parameter by allowing the manipulator arm to be manually overridden. This parameter change enables the operator to disengage from motor control when precise positioning is needed, while the motor remains available for power assistance during movement phases.
3Quantity of substance
If the mass of the load is increased beyond manual handling capability, then the application range is improved, but the inertial forces increase making manual acceleration and deceleration difficult
Solution Approach 1:
The support drive replaces the purely mechanical manual system with a hybrid electromechanical system. The motor provides the force needed to accelerate and decelerate heavy loads, substituting for the insufficient human muscular force. The torque limiter maintains a mechanical connection for manual override, creating a hybrid system that combines motor power with manual control capability.
4Measurement precision
If a torque limiter is introduced to allow manual override, then the manual positioning capability is improved, but the drive support effectiveness may be reduced
Solution Approach 1:
The torque limiter operates periodically, engaging and disengaging based on operational phase. During acceleration and deceleration, the motor provides full power support. During positioning, the torque limiter engages to allow manual override. This periodic switching between full motor support and manual control optimizes both power effectiveness and positioning precision.
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 precise and sensitive positioning of heavy loads by supporting manual force with motor-assisted torques, allowing the worker to correct positions manually, thus overcoming the limitations of conventional hoists and motor-driven systems.
Implementation Method 1
The slipping clutch is designed in such a way that its transmission torque can be overcome by the manual force of the user or worker
Implementation Method 2
The support drive drives the manipulator arm by means of a friction wheel, which rolls on a friction disc
Data Source
Figure 1
Figure 2
AI summary
The lifting tool has manipulator arms (2, 3) that are rotatably supported at respective pivoting hinges (4, 5) with respective vertical rotation axes (6, 7). The manipulator arms comprise a retaining unit (10) for retaining a load (1). Support drives (8, 9) act on the pivoting hinges for pivoting the manipulator arms. A control device (11) is operatable by a user for controlling the support drives during retaining of the load by the retaining unit. One of the support drives include a moment limitation in the form of a slip clutch i.e. friction gear.