Browsing by Subject "pump"

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    A Linear Electromagnetic Piston Pump
    (2017-06) Hogan, Paul
    Advancements in mobile hydraulics for human-scale applications have increased demand for a compact hydraulic power supply. Conventional designs couple a rotating electric motor to a hydraulic pump, which increases the package volume and requires several energy conversions. This thesis investigates the use of a free piston as the moving element in a linear motor to eliminate multiple energy conversions and decrease the overall package volume. A coupled model used a quasi-static magnetic equivalent circuit to calculate the motor inductance and the electromagnetic force acting on the piston. The force was an input to a time domain model to evaluate the mechanical and pressure dynamics. The magnetic circuit model was validated with finite element analysis and an experimental prototype linear motor. The coupled model was optimized using a multi-objective genetic algorithm to explore the parameter space and maximize power density and efficiency. An experimental prototype linear pump coupled pistons to an off-the-shelf linear motor to validate the mechanical and pressure dynamics models. The magnetic circuit force calculation agreed within 3% of finite element analysis, and within 8% of experimental data from the unoptimized prototype linear motor. The optimized motor geometry also had good agreement with FEA; at zero piston displacement, the magnetic circuit calculates optimized motor force within 10% of FEA in less than 1/1000 the computational time. This makes it well suited to genetic optimization algorithms. The mechanical model agrees very well with the experimental piston pump position data when tuned for additional unmodeled mechanical friction. Optimized results suggest that an improvement of 400% of the state of the art power density is attainable with as high as 85% net efficiency. This demonstrates that a linear electromagnetic piston pump has potential to serve as a more compact and efficient supply of fluid power for the human scale.
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    Novel Artificial Urinary Sphincter for Stress Urinary Incontinence Treatment
    (2017-09) Mishra, Avishek
    The American Medical System’s AMS 800TM has been the gold standard for over 40 years with over 150,000 patients treated for Urinary Incontinence and is the leading treatment for male stress urinary incontinence (SUI) following prostate surgery. Type III SUI, or intrinsic sphincter deficiency, is the inability of the urethra to maintain closure pressure sufficient to keep the patient clinically dry at rest and during periods of heightened activity (~120 cmH2O; coughs, sneezes, posture changes, and exercises). The current AMS 800TM is not personalized to a patient’s needs and compromises with an in between pressure- as high (61-70 cmH2O) as it can be without exceeding safety threshold levels. As such many men still leak when they are active. The market is hungry for a device that can adapt to the patient’s level of activity, reducing pressure most of the day to protect the urethra and then briefly increasing the pressure when he is more active. We are developing a novel implantable pump (henceforth called “add-on device”) which will be an add-on to the AMS 800TM and it includes a solenoid coil-cum-plunger and a fluid reservoir within the pump body. The add-on device will be small, light-weight and battery powered, and maintain compatibility with the AMS 800TM device. The device idea is in its proof-of-concept stage. This add-on device can be a possible solution to reducing the risks including urethral atrophy (leading to return of incontinence) and erosion (leading to infection of the implant) resulting from the constant pressure.