Where next for the IC engine?

If you believe the hype, the internal combustion (IC) engine — in the face of ever-stiffening competition from electric and hydrogen-fuelled vehicles — is taking its last sputtering few breaths.

While its role in a range of hybrid powertrains may afford it a stay of execution, give it 20 years, some say, and the engineering innovation that has affected the world more profoundly than any other will be little more than a museum piece.

That’s one view. However, there are many in the automotive industry who believe that a technology now way past its centenary is still far from mature.

There is certainly room for improvement. According to Prof Neville Jackson, director of technology at powertrain specialist Ricardo, the most efficient fossil-fuelled vehicles on the roads today typically only use around 25 per cent of the energy in the tank.

Overall, automotive engineers believe it should be possible to better use this energy by making the kind of incremental tweaks that have characterised the last few decades of engine development. This is the view of Lotus managing director Paul Newsome (see our interview on page 26), who said: ‘I don’t believe there are big step changes, but the incremental biting-off of small percentages. I think there’s still a reasonable amount to go before you say “throw that away and let’s go with a series hybrid”.’

However, while incremental steps are the norm, the IC engine may still have a few more fundamental surprises up its sleeve. One prospect is Ricardo’s 2/4SIGHT concept: a prototype petrol engine based on a 2.1-litre V6 engine, which is claimed to deliver fuel savings of up to 27 per cent by switching between two- and four-stroke operation.

The company has been developing the concept over the last couple of years and is now, following static trials that showed torque output more typical of an engine of twice the capacity, preparing to demonstrate the engine on a vehicle through the 2/4CAR initiative, which also includes Brighton University, parts manufacturer Denso and Jaguar.

Martin Rebhan, Ricardo performance and calibration engineer, said: ‘The programme aims to deliver a global premium vehicle demonstrating a 25-30 per cent reduction in CO₂emissions with no loss of performance, using an innovative, highly downsized gasoline engine with two-stroke/four-stroke switching technology.’

He believes that not only will the engine be easy to package for use on vehicles but that the concept could also be particularly appealing to car makers still wedded to the combustion engine. ‘Radical innovations in combustion engine concepts are clearly likely to be seen as attractive due to their familiarity to existing design and manufacturing systems,’ added Rebhan.

Although a radical concept, he believes it has enough fundamental similarities to existing engines not to put manufacturers off. ‘The 2/4SIGHT is, in my eyes, not a fundamental redesign of an engine,’ said Rebhan. ‘All techniques and methods used in 2/4CAR are already well developed or have solutions that will not present manufacturing problems. This makes 2/4SIGHT attractive because the base 2/4CAR engine will not be radically different from an existing 2-litre engine. The main work apart from designing the valve train and dimensioning the boost components correctly is the development of an overall control strategy, which is the focus of much calibration/simulation work.’

Meanwhile, beyond the continued incremental improvements and the occasional, potentially game-changing, mechanical rethink, the life of the IC engine could also be prolonged by the availability of new types of fuel, from CNG to biofuels and — perhaps most intriguingly — hydrogen. Hydrogen and cars are hardly strange bed-fellows. Before the current electric bandwagon gathered momentum, hydrogen as a power source for fuel cells was viewed as the most likely contender. However, engineers are increasingly interested in using the most abundant element in the universe to fuel IC engines.

Last year, Sheffield-based ITM Power demonstrated a Ford Focus modified to run on hydrogen, while various manufacturers, from BMW to Mazda, have also shown prototypes designed to run on the gas. Perhaps the most promising of the these is the Mazda RX-8 Hydrogen RE, which is already being leased in Japan.

Back in the UK, ITM — which has developed its own hydrogen production system — recently announced that it had joined forces with Essex-based automotive consultant Revolve to accelerate the development of hydrogen-fuelled vehicles for the UK market.

The two companies have already worked on the conversion of a small fleet of commercial vehicles and believe there is an opportunity for the technology. According to Steve Pegrum, senior engineer at Revolve, one of the big attractions is that, barring a few modifications, it is really not difficult to get an engine to run on hydrogen. ‘When you inject hydrogen into a combustion chamber, it takes up more volume,’ he said. ‘Consequently, you have to pressure charge the engine — that’s one of the fundamental changes. We’ve also changed the spark plugs because, although it’s very easy to burn hydrogen, the difficult bit is doing it in a controlled manner, so we’ve put colder-rated spark plugs in the combustion chamber to try and draw heat away from the combustion chamber.’

Capable of up to 100 miles (161km) on a 4.5kg fuel capacity, the engine chosen by Revolve was originally developed to run on CNG and therefore already has hardened valve seats and valves. This, said Pegrum, makes it suitable for hydrogen, which — like CNG — has no lubricating properties.

Pegrum believes that the IC engine has a potentially critical role to play as a bridging technology to gain acceptance for hydrogen as a fuel. ‘Trying to get an infrastructure in place with the high cost of the fuel-cell vehicle is simply not attractive enough, whereas introducing hydrogen through the ICE and allowing the infrastructure to come, people get used to hydrogen and the hydrogen economy and half the job’s done,’ he said. ‘It’s also much more attractive to the car makers as they don’t have to turn their back on the technology they know — the IC engine. We know a lot about it; they’ve been around for a long time and there’s an awful lot of them — converting is not difficult at all and we’ve got such a fantastic wealth of history it would be silly not to use them, especially when we can put nothing out the tailpipe.’

Sidebar

Backstory - Daimler oil motor

In April 1893, The Engineer reported on the birth of the petrol engineWe illustrate a very ingenious and interesting form of oil engine, designed by Mr Daimler, for many years associated with the late Dr Otto.

It is made in various forms for ordinary fixed motor purposes, for fire engines, for tramways, for light carriages and quadricycles and very numerously for launches and pinnaces.

The engines work with the lighter oils or rectified petroleum, called motor benzine or petrol, which has a specific gravity from 0.68 to 0.7.

The principle on which all the forms of the engine work is the same. The engine is completely encased in a cast-iron crank chamber, which contains, in the form shown in our detail engravings, four vertical and parallel cylinders.

The pistons in these are provided with three cast-iron rings and the connecting rods are attached to the piston direct and to the four cranks of a cast steel shaft.