Dynamical Analysis Of Bilge Pump Moving Parts And Investigation Of Fault Diagnosis

As an important equipment of the ship，the bilge pump is used for transporting the bilgewater and sewage. The reciprocating bilge pump which is located at the bilge generally ischaracterized by small volume and high pressure, and it would be maintained inconvenientlyafter fault. Therefore it is very important to enhance the reliability of the bilge pump.The in-cylinder pressure was calculated，the shaft vibration was analyzed and theexperiment was researched on meshing abrasion of the worm and worm wheel of the bilgepump. The main content of this paper include:Firstly, a equation of in-cylinder pressure was established, the changing rule ofin-cylinder pressure was derived. And then the dynamical characteristics of the cranklinkmechanism were analyzed, the unbalanced torque of crank and the overturning moment whichwas processed by the body were obtained.Secondly，the torsional free and forced vibrations of the bilge pump were calculated andtested. Comparing with the traditional model in which the torsional stiffness of meshing pairwas set to be infinite，the finite torsional stiffness was used for calculation. The equivalentsystem model of torsional vibration of the bilge pump was established. The error of theformer two natural frequencies which were derived from calculating and testing was within5%, and the error of the results which were derived from calculating and testing of thetorsional forced vibration was10.6%. The reason of the bilge pump fault which was inducedby the additionally torsional contact stress was found. The fault was resolved from minishingthe additionally torsional contact stress by changing torsional stiffness and contact area bymodifying the tooth profile and adjusting the central distance.Finally，the fault diagnosis of the bilge pump was preliminarily studied by adopting theacceleration and load identification method, the experiment shows that the variety of the totalvibration level of each measuring point is not obvious by using the acceleration to monitoringthe normal and fault condition of the bilge pump online. The approach was advocated that thefault was diagnosed by the characteristic of the force, it shows that the parameter variety ofthe normal and fault condition of the bilge pump can be characterized by the means，and thefault can be found accurately. Furthermore, the load identification method can also bereferenced on the fault diagnosis of the other reciprocating mechanism.