New tech makes hybrid buses cost-effective

Artemis's new Digital Displacement (DD) power system this year received the company a prestigious Regal Academy of Engineering MacRobert Award.

The company, owned through Mitsubishi, hit the head lines earlier this year when a 7MW (megawatt) wind turbine containing an electronic Displacement transmission (DDT) hydraulic system was deployed to work as a floating wind-turbine within deep water 20 kms off Fukushima. It's the biggest floating wind-turbine in the world.

So far hydraulic pumps and engines have been controlled by different the stroke of aide with an adjustable mechanism, but they have proved inefficient for auto transmissions and wind turbines.

In comparison, the output of a DD pump motor or motor is managed by digitally enabling person cylinders containing electronically-controlled electronic valves. Individual cylinders could be switched from idle in order to pumping cycle once each and every shaft revolution, in a design determined by an embedded control. This provides results in a faster and more accurate control reaction compared to variable-stroke machines.

"We developed digital displacement hydraulics, which is a way of turning off the capability that you don't need without bringing in a parasitic loss, which was the fundamental starting point to create very efficient hydraulics that was both controllable and worldwide to very big weighing scales, " explained chairman as well as founder of Artemis, Doctor Win Rampen.

According to controlling director, Dr Niall Caldwell, "conventional hydraulics have some disadvantages, particularly efficiency, controllability, and also noise. So digital shift is a fundamental rethinking associated with hydraulic power technology, that embeds electronics and software program, digital control at the heart from the machine and that revolutionizes hydraulic technology to become much more effective, much more controllable, and more tranquil. "

Artemis is focusing on various projects to enable substantial reduction in the fuel usage of commuter trains and busses. A regenerative braking power storage system using their DD technology showed fuel usage reductions by 10 percent, and is retrofitted to existing diesel powered trains. It also produces much less noise and cuts wear out emissions within stations.

The opportunity of hybrid buses is much more impressive, with fuel cost savings of 27 percent confirmed on tests carried out upon vehicles used by Lothian Busses, made by manufacturer Alexander Dennis.

Caldwell says the technology will pay for itself within two or three many years, meaning that there is no need for any federal government subsidy, a particularly important factor inside developing countries. In addition , this uses conventional materials, instead of expensive ones often used throughout mainstream electric hybrid technologies.

"What we're trying to perform is make a hybrid technological innovation that is very low cost, it can made with conventional materials for example steel, rather than exotic along with rare materials such as lithium, which can really be applied internationally to make a hybrid system which pays for itself as a company case, without subsidy, and that we think that's the key to creating all the world's buses mixed-style models, " he said.

Artemis has also adapted DD mixed transmission for a car, particularly its BMW 530i, which usually it has been driving visitors to the site around in because 2008. Independent tests revealed double the fuel economy with city driving compared to the exact same car with a six pace manual transmission, along with 30 % lower carbon dioxide emissions.

Because he drove the car round the company's Midlothian factory in addition to demonstrated how it worked well, Caldwell told Reuters: "Conventional electric hybrid mixes the potency of the engine with that of the electric motor and an electrical battery. In contrast our hydraulic hybrid mixes the power of the actual engine with a hydraulic electric motor and a hydraulic battery, that is otherwise known as an accumulator, which stores the energy regarding braking the vehicle in the form of compacted gas. "

According to Rampen, part of the beauty of DD is the fact that its power rating may be increased dramatically by replicating multiple hydraulic components inside a single system.

He stated: "The power rating might be increased very dramatically, up to now up to 7 megawatts, just by making a module and then replicating it around a machine to create a very high-powered machine. But additionally these modules tend to be instead small within themselves and thus they're easy to take out as well as replace, and when you're dealing with offshore wind, particularly, wherever access is very difficult and also expensive, to be able to dismantle along with replace any one component within this very inaccessible place is essential. "

Rampen says the MacRobert Award has created huge worldwide interest in Artemis.

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