According to Norwegian company Rapp Hydema AS, an exhibitor at Bergen, the motors used to power today’s winches are oversized, overweight, and old technology. Recognising this, the company has researched other ways to manufacture these electric motors.
The challenges for an electric motor to be used in a maritime environment are many. The electric motors currently available “off the shelf” are standard items with air-cooling, not the ideal solution for the purpose Rapps customers are using them for.
To resolve the problems facing electric systems a few winch manufacturers have now chosen to install their motors in a housing, cooled by a water jacket. However, the rotating parts cannot come into contact with the water, and cooling is therefore less than ideal.
What Rapp Hydema has done is build a liquid-cooled electric motor which circulates the fluid through the rotating electric parts of the motor. The electric motor is watertight and encapsulated, says development engineer Ben Bolsøy.
A unique concept
The Bodø firm has been working on this innovative powerplant for a long time as a very exciting development project. The result is a unique motor concept which has never been offered before.
The programme started with a standard, air-cooled motor, which was then sealed and had a special type of fluid pumped through the rotating parts. This was as close to a non-conducting fluid as could be found, says Bolsøy, who, with the capable assistance of the rest of the development team, has been running a series of tests on the motor.
At the conceptual study there were many technical details that needed clearing up, such as heat generation, flow losses, and making the motor fluid-tight so that coolant does not escape.
Rapp Hydema AS has applied for patents for the concept, and two major electric motor manufacturers were contacted. The company then performed technical feasibility studies with these manufacturers who allowed Rapp to see the detailing and production drawings and in return was candid about its own tests, adds Bolsøy.
Revolution onboard
Rapp Hydema is currently checking the product for mass production. “We are now at the point where we will execute a full scale test of the product”, says Bolsøy
“Now we can pump the cooling fluid into the motor where heat is generated and all the problems are caused – and out again to the outside and through a heat exchanger. That gives us full control of the temperature. We can extract several times the kilowatts that the engine initially produced. So the benefits are minimal build size, smaller units onboard, but more power per unit. A whole raft of savings can be expected to ensue as a result. If a fault occurs, then because the units are smaller, they can be flown to a workshop at lower freight costs. The advantages are legion” claims Bolsøy.
