Pneumatic Pump Box Layout and Bladder Accumulators for Fluid Therapy
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Solution Overview
Problem
Medical fluid delivery machines, particularly those using pneumatic pumping for renal failure therapies, face challenges with corrosion due to water in compressed air, limited accumulator lifespan, and heat management, which affect efficiency and reliability.
Innovation Solution
The design incorporates a pneumatic pump box with a vacuum pump at the top to minimize heat impact, a dryer to remove water from compressed air, and elastic bladders in accumulators to extend the delivery of positive and negative pressures, along with efficient tubing routing and sound insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If water is present in compressed air from the compressor, then the compressor can operate normally, but corrosion occurs in the solenoid valves and accumulator
Solution Approach 1:
A dryer is introduced as an intermediary component between the compressor and the accumulator/solenoid valves. The dryer removes water from the compressed air through desiccation or condensation, allowing the compressor to operate normally while protecting downstream components from water-induced corrosion
Solution Approach 2:
The harmful element (water) is extracted from the compressed air stream using the dryer. By removing water before the air enters the accumulator and solenoid valves, the system maintains reliability while allowing continuous compressor operation
2Stress or pressure
If the compressor runs continuously to maintain positive pressure, then pressure stability is improved, but heat generation increases and water accumulation occurs
Solution Approach 1:
Instead of continuous operation, the compressor operates periodically or intermittently to recharge the accumulator when pressure drops below a threshold. This periodic action maintains pressure stability while reducing cumulative heat generation and water production in the compressed air
Solution Approach 2:
The dryer extracts water from the compressed air during each compressor cycle, preventing water accumulation that would otherwise increase with continuous operation. This allows pressure maintenance with reduced thermal and moisture burden
3Volume of stationary object
If the vacuum pump is placed at the bottom of the pump box, then space utilization is improved, but heat from the vacuum pump affects other components
Solution Approach 1:
The vacuum pump is repositioned from the bottom (vertical dimension) to the top of the pump box. This dimensional change in placement allows heat to rise away from sensitive components while still utilizing the pump box volume effectively, resolving the thermal interference issue
4Strength
If accumulators use rigid housing only, then structural strength is improved, but the delivery duration of pneumatic pressure is limited
Solution Approach 1:
The accumulator combines a rigid housing (for structural strength) with an elastic bladder (for extended pressure delivery). The rigid housing maintains structural integrity while the elastic bladder stores additional pneumatic energy, extending the duration of pressure delivery beyond what a rigid housing alone could provide
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
This configuration enhances the thermal efficiency, extends the usability of pneumatic pressure accumulators, reduces noise, and ensures reliable operation, including during power loss, by maintaining pneumatic pressure and improving the robustness of the medical fluid delivery system.
Implementation Method 1
an accumulator storing the negative pressure created by a vacuum pump
Implementation Method 2
an accumulator storing the positive pressure created by a compressor
Data Source
AI summary
A medical fluid delivery machine including: a medical fluid pump including a pneumatically actuated pump chamber and first and second pneumatically actuated medical fluid valve chambers located respectively upstream and downstream of the pneumatically actuated pump chamber; a vacuum pump for creating negative pressure; and an accumulator storing the negative pressure for operation with at least one of the pneumatically actuated pump chamber, the first pneumatically actuated medical fluid valve chamber or the second pneumatically actuated medical fluid valve chamber, the accumulator holding an elastic bladder that inflates under negative pressure from the vacuum pump applied to an outside of the elastic bladder, creating additional negative pressure that increases the amount of negative pressure that the accumulator can provide.