Stretcher Winch Tension Control and Modular Strap Design
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Solution Overview
Problem
Existing devices for loading and unloading stretchers on inclined planes lack safety, as they can cause sudden and uncontrolled descent when obstacles are encountered, and require complex maintenance procedures for the winch and strap.
Innovation Solution
An auxiliary loading device with a winch, sensor unit, and electronic control unit that detects tension in the strap and automatically stops unwinding when tension drops, combined with a spool design allowing easy strap removal and replacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the motor of the winch continues to unwind the strap after the stretcher stops due to an obstacle, then the motor operates continuously to complete the unloading stroke, but the stretcher suddenly resumes descent without control when the obstacle is removed, causing safety hazards
Solution Approach 1:
The patent implements a feedback mechanism where a sensor detects the position of the stretcher on the inclined plane and sends signals to the control unit. The control unit continuously monitors the stretcher's position and automatically stops the motor when the stretcher reaches the bottom or encounters an obstacle, preventing uncontrolled descent. This closed-loop control system ensures safety while maintaining operational efficiency.
2Stability of the object's composition
If the strap and motor are designed as integrated permanent components of the winch, then the structural integrity is maintained, but the installation and maintenance operations become complex and time-consuming
Solution Approach 1:
The patent divides the winch system into separable modular components: the motor, the strap, and the support frame are designed as independent replaceable parts. The strap can be detached from the spool, and the motor can be removed from the support frame, allowing each component to be independently maintained or replaced without affecting the entire system. This modular design simplifies maintenance while preserving structural integrity during operation.
3Ease of repair
If the winch components are designed for easy removal and replacement, then maintenance operations are simplified and sped up, but the installation and securing processes may become less secure
Solution Approach 1:
The patent incorporates preliminary securing actions in the design of connection elements. The strap features pre-formed attachment points and fastening mechanisms that ensure secure connection to the stretcher before operation begins. Similarly, the motor and support frame include pre-designed mounting interfaces with locking features that guarantee secure installation. These preliminary security measures are built into the component design, allowing easy removal during maintenance while ensuring secure attachment during operation.
Data Source
AI summary
An auxiliary loading device of a stretcher including a winch having a support frame rotatably supporting a spool, a tow strap wound on the spool and having a tow hook attachable to the stretcher, and a motor connected and configured to rotate the spool in a first direction for winding the tow strap on the spool and in a second direction for unwinding the tow strap from the spool. A sensor is connected to the winch to detect a value of a parameter indicative of a tension of a unwound section of the tow strap including the tow hook, and an electronic control unit operatively connected to the sensor unit and the motor of the winch to stop rotation of the spool when operated to rotate in the second direction if the value of the parameter indicative of the tension is less than or equal to a reference value.