Carrier Drive Unit Air Spring Traction Control
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Solution Overview
Problem
Existing patient handling and medical equipment carriers face issues with compressor overheating due to pneumatic system leaks, loss of traction during power interruptions, and wastage of battery charge during inactivity.
Innovation Solution
A drive unit with a processor-controlled pneumatic system that includes a normally closed air relief valve, runtime control for the compressor, and a mechanism to conserve battery charge by shutting down the unit during inactivity, maintaining drive wheel traction through air spring pressure and preventing overheating by limiting compressor duty cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the air compressor runs continuously to maintain pneumatic pressure, then the drive wheel traction is maintained, but the compressor overheats due to excessive duty cycle
Solution Approach 1:
The control system operates the air compressor in periodic cycles rather than continuously. The compressor runs during scheduled intervals to recharge the air spring, then stops to cool down. This periodic operation pattern maintains adequate pneumatic pressure for drive wheel traction while preventing compressor overheating by enforcing rest periods between compression cycles.
2Ease of operation
If the drive wheel is kept in contact with the supporting surface for traction, then propulsion is enabled, but battery charge is wasted during periods of inactivity
Solution Approach 1:
The drive wheel's contact state with the supporting surface is dynamically adjusted based on operational needs. During active propulsion, the air spring maintains the drive wheel in contact with the surface for traction. During periods of inactivity, the system shuts down and allows the drive wheel to lift off the surface, eliminating energy consumption. This dynamic state transition enables the system to have both propulsion capability when needed and energy conservation when not in use.
3Reliability
If the normally closed air relief valve remains closed to maintain pneumatic pressure, then drive wheel contact force is maintained, but the system cannot release pressure safely during shutdown
Solution Approach 1:
The normally closed air relief valve is integrated into a feedback-controlled system. During normal operation, the valve remains closed to maintain pneumatic pressure and drive wheel contact force. During shutdown, the control system detects the inactive state and automatically opens the relief valve to release pneumatic pressure. This feedback mechanism ensures the valve operates in the appropriate state based on system conditions, maintaining reliability during operation and preventing harmful pressure accumulation during shutdown.
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 effectively prevents compressor overheating, maintains traction during power interruptions, and conserves battery charge, ensuring safe and efficient operation of patient handling and medical equipment carriers.
Implementation Method 1
An air spring is provided for counterbalancing the extension spring and biasing the drive wheel into contact with the supporting surface
Implementation Method 2
The pivot arm is resiliently biased by an extension spring such that the drive wheel is out of contact with the supporting surface
Data Source
AI summary
A drive unit for a carrier that includes a chassis with a drive wheel that is pivotable with an air spring in and out of contact with a surface over which the carrier is propelled. The air spring is in a pneumatic system including an air compressor which is connected to a processor in an electrical system. The compressor is programmed to provide a fair safe mode for the drive wheel, a runtime control for the air compressor and a battery voltage sensing circuit to shut down the electrical system during periods of inactivity.