Design And Reliability Research Of Urethra Valve Of Bladder Power Pump

Neurogenic bladder is a term applied to a malfunctioning urinary bladder, which is caused by the injured central nervous that controls urination. Some complications can be caused by the disease, such as bladder stone, urinary system infection, renal failure and so on. It can bring great pain to patients, and the treatment of the disease or assisting micturition has been generally acknowledged as difficult problem by medical researches. There is no effective way to the neurogenic bladder at present. In order to solve the problem, a bladder power pump driven by an external electromagnet was proposed. An external electromagnet produces electromagnetic force which acts on a magnetic mover, and the tension of magnetic mover makes the orifices of ureters and urethra close and open. As a result, the urine of urinary bladder is continuously discharged by the press of magnetic mover. The feasibility of the working principle of the pump was proved by simulated experiment. But, a great electromagnetic force for opening the orifice of urethra and a big electromagnet were required. To optimize the structure of the pump, the distribution mechanism of the pump should be improved.Therefore, a new urethra valve of the bladder power pump was designed in this paper. The mathematical model of the urethra valve was built based on the theories of electromagnetics and hydromechanics. The model was used to analyze the characteristics of the urethra valve effected by different electromagnet current, air gap and so on. The validity of the model was confirmed through the comparison between simulation and experiment. The effects of the urethra valve on the micturition performance of the pump were studied on simulated experiment system. The results show that increasing electromagnet current and decreasing air gap between the electromagnet and the urethra valve are beneficial to increasing maximal urine flow rate and decreasing urine flow time.The urethra valve is a major part of the pump for realizing flow distribution of urine. Once the urethra valve is in fault, the pump will lose the function of assisting micturition. So, it is important to study the reliability of the urethra valve. In order to improve the reliability of the urethra valve, a simulation model of the reliability of the urethra valve was built based on the structure principle and fault tree of the urethra valve. According to the principle of the Monte Carlo method, a simulation algorithm of the reliability of the urethra valve was proposed. Some reliability indexes of the urethra valve were calculated, such as reliability, failure probability, importance of bottom events, mode importance and so on. The simulation and experiment results showed that the reliability of the urethra valve is0.73when the life is50000times; both shedding and aging of elastic band are the weaknesses of the urethra valve.The conclusion can provide the basis for performance analysis and structural optimization design of the bladder power pump, and provide the guidance for the design of new device for assisting the bladder micturating, as well as the guidance for the design of biomedicine device.