News Column

Patent Issued for Method and Arrangement for Propeller Pitch Control

July 30, 2014

By a News Reporter-Staff News Editor at Defense & Aerospace Week -- A patent by the inventor Forsstrom, Jan-Olov (Kristinehamn, SE), filed on October 12, 2009, was published online on July 15, 2014, according to news reporting originating from Alexandria, Virginia, by VerticalNews correspondents.

Patent number 8777575 is assigned to Rolls-Royce Aktiebolag (SE).

The following quote was obtained by the news editors from the background information supplied by the inventors: "The use of propellers providing adjustable pitch is of importance regarding many ships, to enable optimization of the propulsion. A conventional system to arrange for adjustability of the pitch of the propellers is based on a rather powerful hydraulic system. For many ships hydraulic systems requiring about 30 kW power are needed. It is evident that such a large need output of power implies disadvantages. This is especially apparent taking into account that there is always some leakage in big hydraulic systems and therefore the system has to be up and running more or less continuously, not at least to achieve sufficient cooling. As a consequence such an hydraulic system is rather costly. Moreover it leads to the creation of noise, which in many installations is undesired. Furthermore it necessitates a rather complex shaft design, since the shaft has to enable both supply and drainage from the two pressure chambers used in connection with a hydraulic piston that actuates positioning of the propeller pitch adjustment device. Finally it is also a hazardous design with regard to the environment, since it may lead to leakage of oil into the nature.

"From U.S. Pat. No. 5,498,135 there is known a Propeller Pitch Control Arrangement, comprising a propeller hub having a number of interface fittings for adjustable pitch positioning of a propeller blade, a positioning device, within said hub, having a number of propeller control interfaces and an actuator arrangement, comprising a motor device (in the form of an electrical motor) positioned adjacent said hub, arranged to move and position said positioning device to enable varying pitch for said propeller blades. However, this known solution uses a reduction gear in combination with a drive spool and pitch ring, which makes the design bulky and complex, which probably is the reason why that design concept has not been any success. Also WO9631390 and US 20040157509, in a similar manner present solutions that are bulky and complex, e.g. by the use of a non-unitary hub body in WO9631390 and by the use of an adjustment device forming multiple bodies in US 20040157509."

In addition to the background information obtained for this patent, VerticalNews journalists also obtained the inventor's summary information for this patent: "It is an object of the invention to eliminate or at least minimize the problem mentioned above, which is achieved by means of a method and an arrangement according to the independent claims.

"Thanks to the invention there is created an arrangement that requires considerably less power in-put compared to conventional systems and which is both compact and relatively simple in its design. As a consequence the arrangement would be considerably less costly both initially and also during use. Moreover it will facilitate a much more reliable solution regarding environmental aspects such as elimination of oil leakage. Furthermore it provides an arrangement that is much less noisy than conventional systems. All in all the new arrangement provides synergistic advantages that must be seen as surprising. Especially in combination with the use of a self braking transmission between the pitch adjustment device and the rotatable shaft these advantages are indeed surprising, since thanks to the use of a self braking interaction there will be no need for any other additional means to safe guard control to achieve a desired positioning, enabling a very compact design.

"Further aspects and advantages of the invention will be more apparent in relation to the following detailed description."

URL and more information on this patent, see: Forsstrom, Jan-Olov. Method and Arrangement for Propeller Pitch Control. U.S. Patent Number 8777575, filed October 12, 2009, and published online on July 15, 2014. Patent URL:

Keywords for this news article include: Aerospace and Defense Companies, Rolls-Royce, Rolls-Royce Aktiebolag.

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Source: Defense & Aerospace Week

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