Reduced-Pressure Therapy Pump Using Motor-Voltage Feedback
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Solution Overview
Problem
Current differential pressure control systems for reduced pressure treatment require two pressure sensors, increasing size, weight, cost, and complexity, limiting their use for low-severity wounds and ambulatory patients, and posing infection risks due to additional components connected to the pneumatic circuit.
Innovation Solution
A system that controls supply pressure using a motor-driven pump without a pressure sensor, utilizing a controller to monitor motor voltage and adjust power to maintain target pressure, with a single pressure sensor for applied pressure measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two pressure sensors are used to measure supply pressure and applied pressure, then differential pressure control and leak detection are achieved, but system size, weight, cost, and complexity increase
Solution Approach 1:
The patent extracts the supply pressure measurement function from the pneumatic circuit by using the motor's electrical characteristics (current, voltage, speed) to infer supply pressure. This eliminates the need for a pressure sensor in the supply line, reducing system complexity while maintaining differential pressure control capability through the single applied pressure sensor
Solution Approach 2:
The patent replaces the mechanical pressure sensing system (pressure sensor) with an electrical measurement system (motor current, voltage, speed monitoring). By monitoring motor electrical parameters and using the known relationship between motor load and supply pressure, the system determines supply pressure without mechanical contact to the pneumatic circuit
2Reliability
If two pressure sensors are used for differential pressure measurement, then leak and blockage detection is improved, but system weight increases
Solution Approach 1:
The patent replaces the second pressure sensor (supply pressure sensor) with an electrical monitoring system that measures motor current, voltage, and speed. These electrical parameters are easily measurable and provide indirect but accurate information about supply pressure conditions, enabling leak detection without additional heavy hardware
3Extent of automation
If additional pressure sensors and electronic circuitry are added, then pressure control capability is improved, but cost increases
Solution Approach 1:
The patent makes the motor serve dual functions: not only does it drive the pump, but it also acts as a sensor by providing electrical characteristics (current, voltage, speed) that indicate supply pressure conditions. This self-service approach eliminates the need for separate pressure sensing electronics in the supply line, reducing overall electronic circuitry complexity while maintaining automated pressure control
4Reliability
If a pressure sensor is connected to the pneumatic circuit for supply pressure measurement, then supply pressure feedback is achieved, but infection risk increases
Solution Approach 1:
The patent extracts the supply pressure measurement function from the pneumatic circuit entirely by using electrical measurements of the motor. This removes the physical connection point that would allow bacterial contamination to enter the sterile field, eliminating the infection risk associated with supply pressure sensors while maintaining the ability to monitor and control supply pressure through electrical parameters
Data Source
AI summary
An apparatus and method for managing reduced pressure at a tissue site are disclosed. The apparatus comprises a pump for supplying reduced pressure to the tissue site, a motor coupled to the pump to propel the pump, and a drive system electrically coupled to the motor that includes a power source that provides a source of direct current power to the motor during an operational period at a substantially constant current and of sufficient magnitude to supply a targeted reduced pressure during the operational period. The drive system also includes a controller that monitors the pump's loading on the motor by measuring the voltage across the motor to determine whether the motor voltage remains within a predetermined operational range of voltages necessary for maintaining the reduced pressure supplied by the pump proximate to the targeted reduced pressure without directly measuring the reduced pressure using a pressure sensor.