Patch work

A simple patch to the software that controls car systems can reduce fuel consumption by 2.6 per cent by making orthodox cars work more like hybrids, according to research from The Netherlands.

The study, by the mechanical and electronic engineering departments at the Technical University Eindhoven, started as PhD work with Ford’s Research Centre in Aachen, Germany. Dr John Kessels and Dr Michiel Koot’s work on control systems gave results that prompted them to study how best to implement the software alterations in the vehicle and carry out further tests.

The patch helps save fuel in a number of ways. With it installed, excess power can be used to charge the battery, or the generator can be turned off when it is inefficient to do so. Electricity, which can be stored in the battery, can be generated when the car brakes. Finally, electric systems, such as rear window and seat heating, can be partly shut off during use.

‘The best way to explain the software is to compare it with a regular vehicle,’ said Kessels. ‘You have the alternator, which provides all electric loads when you switch them on. For example, if you switch on the seat heater you get additional power directly from the alternator to supply it.

‘When these systems are on, the efficiency depends on the operating point of the combustion engine. We can decide to generate only when it’s efficient to do so, and when it isn’t we shut off the generator and use the battery to provide all electric loads. With systems like the heaters, you can have them on lower or not at all for a short period, and usually the user won’t notice.

‘Normally the engine and the alternator are connected with a belt or in some other manner,’ said Kessels. ‘By turning off the alternator, you ask for more energy from the engine, changing its operating point by a small amount, because the mechanical power demand you need for driving is huge compared to the electric power. But you still have some freedom to change the operating point of the engine and manage improved fuel economy.’

The researchers installed their system in a Mondeo and tested it on a roller rig used for vehicle benchmarking at Ford’s Aachen facility. They applied the same test cycle used to measure CO2 emissions for European legislation before bringing a vehicle to market.

‘Using our vehicle prepared with the energy management system, we got 2.6 per cent fuel saving,’ said Kessels.

At the moment, the system only controls the car’s electrical systems, but the next step would be to find a way to shut the engine off when it is idle, giving a potential saving of five to six per cent. This would, however, require significant adjustments to the car, including installing a more powerful starter motor and an automatic gearbox.

The researchers also want to investigate how to take more accurate fuel efficiency measurements as the vehicle is being driven.

‘Most systems are only measured once for a new vehicle, but after a while the engine needs to have check-ups and maintenance every few years, said Kessels. ‘We envisage incorporating an update of the system and control strategy in a service, so the best thing to do is measure it online.’

He admits that more research needs to be done on the battery, as further demands would be made on it. ‘We know the battery will degrade a bit quicker, and it is important that you never have to replace a battery so early that the benefits of fuel economy are outweighed by its cost. You can, however, tweak the software so the battery is not ruined in a couple of months,’ he said.

According to Kessels, even though batteries have been in vehicles for more than 40 years, no-one has yet got to the bottom of the degradation process. ‘I think that’s an appealing project to get more inside information about how the battery works and how degradation happens,’ he said. ‘The problem is, you often only know after you have ruined it, which makes experiments difficult and costly in terms of the number of batteries needed. We need to find a more economical way to get the information we need.’

Kessels believes the major contribution of the research is easily-achievable fuel savings.

‘Although it is not a huge gain, if you have installed the system, you can have it for relatively less cost and fewer changes to the vehicle than other solutions,’ he claimed.