Electric Actuation of Controllable Pitch Propellers

Abstract: This bachelor’s degree project has been conducted at the Innovation and Design Engineering programme at Karlstad University and responds to 22.5 ETCS credits. The project has been carried out in co-operation with Rolls-Royce AB in Kristinehamn. Based upon a virtual order concerning a super yacht the objective has been to develop a controllable pitch propeller that is adjusted using electro mechanics, to eliminate the use of hydraulic oils and thus the risk of leakage to the seawater. The pre-study consisted of the two first phases of QFD-analysis (Quality Function Deployment). The first phase consists of gathering customer requirements. Representatives from different functions within Rolls-Royce AB were interviewed, as representatives for the customer. The demands they presented were used to find product features and functionalities. The results were put together in two Houses of Quality. The first house shows the relations between requirements and features/functionalities and their respective relevance in correlation to each other. House of Quality two describes the relations between features/functionalities and design solutions in a similar way. Based upon the QFD-analysis, a specification was generated to be used as guidance to generate ideas of how to solve the problem. A number of brainstorming methods were used and students from Karlstad University and Rolls-Royce AB participated in those sessions. Overall, some twenty ideas were gathered and five of those were considered feasible concepts. For further development, two of those concepts were chosen, using relative and weighted decision matrixes. This development consisted of solid modelling, based on current propeller arrangement designs, and stress calculations of the new parts of the system. Both concepts consist of an electrical engine, powering a trapezoid screw, which moves the crosshead. In Concept 1, the screw is mounted directly into the crosshead while in Concept 2; a push rod is used to transmit the motion. Both concepts appeared to meet up to the objectives, though Concept 1 fulfilled more demands and to a greater extent. For further development of this product, customer inquiries with closer customer contacts need to be conducted. It will also be necessary to contact the concerned classing societies, since current classification rules not can be applied to electromechanically controlled propellers.