Pump action

A variable flow oil pump designed by UK engineers is claimed to use significantly less power than conventional fixed flow pumps. Jon Excell reports.

An innovative pump designed by UK engineers could lead to major improvements in the energy-efficiency of the oil systems used in diesel engines.

Developed by Birmingham’s Concentric, the new variable flow oil pump (VFP) is said to use significantly less power than conventional fixed flow pumps.

Indeed, the pump has demonstrated savings for heavy-duty engines of between 3 and 4hp at rated speed and more than 1hp at cruise speed.Concentric’s design office manager Kevin Johanson explained that the problem with the kind of positive displacement pumps typically used is that they are completely linear.

‘The faster you run them the more you get out of them,’ he said. With the amount of oil coming out of the pump limited either by a safety release valve or pressure regulator, and the rest of the oil either recirculated within the pump or dumped straight into a sump, there’s clearly room for improvement.

By contrast, VFP s closely match oil supply to demand and are therefore able to take advantage of the differing oil requirements for each point in an engine’s operating cycle, thus enabling fuel savings to take place.

Johanson said that Concentric has been working on variable flow pumps for the past 30 years, but early models weren’t very robust and didn’t enable very large fuel savings. Then, around 12 years ago, following some ‘serious interest’ from a Japanese automotive group, the company developed an alternative design.

But while this pump allowed greater fuel savings, it was still somewhat impractical from a commercial perspective. ‘It was very expensive and in order to get it to work we had to make it very robust — it had all sorts of great big bearings on the outside to make it durable — it was just way too expensive,’ he said.

Fast-forward a few years, and following something of a hiatus where reducing emissions became the main thrust of automotive R&D, the fuel-efficient pump has now become more desirable than ever.

Johanson explained that driven by this renewed interest, his design team set about developing a product that would still contribute to fuel reduction, but at the same time be easy to manufacture and relatively cheap. The company managed to do this by designing a product that could be built from ‘known technology’; in other words the kind of standard components found in conventional pumps. Johanson said that the new design is around 75 per cent cheaper than previous incarnations.

The fuel savings made possible by the pump are largely dependent on how the technology is adopted, claimed Johanson. ‘if you just stick it on you’re not going to get all the benefits — you need to adopt a complete system approach.’

Taking this into account he said that fuel savings of around one per cent are very much achievable.

While this may not sound like a hugely dramatic figure, it is thought that it could lead to massive savings in the pump’s most likely application; within the engines of heavy-duty trucks. Across a whole fleet of such vehicles, a one per cent saving equates to a lot of money.

Despite this, Johanson said that owing to the truck industry’s traditional reticence when it comes to new technology, the first application is likely to be on a car rather than a truck. He declined to reveal the identity of potential customers, but said that the pump is likely to enter series production around 2007.