A quarter of a century ago, the turbocharger was regarded as a "tuning tool"-a relatively cheap way of giving a car engine a performance advantage over a normally aspirated one. Although it had been around at that time for many decades-Swiss engineer Dr. Alfred Buchi patented the concept in Germany in 1905-its new-found popularity in the 1980s was due to its use in motorsport, specifically Formula One. Although Renault was the first manufacturer to race a turbocharged Grand Prix car in 1977, it was not until 1983 that such an engine achieved any notable success when Nelson Piquet won the World Championship driving a BMW-powered Brabham. It was then that the demand for turbochargers was unleashed, firstly satisfied by the aftermarket sector and then by automakers who latched onto it as the boy racer's upgrade on the go-faster stripe down the side.
The automakers' fixation with the gadget lasted about 10 years. The death knell came in 1989, when the device was banned in Formula One. It consequently fell from grace and the turbocharged gasoline engine had become somewhat of a distant memory in the ‘90s.
Fortunately for the turbocharger manufacturers, though, their market did not wither and die on the vine because the popularity of the small displacement diesel engine in Europe was on an upswing for passenger cars. In 1970 diesel penetration in Europe accounted for just 1%, and even though it grew in the following years, it still only accounted for 6.5% in 1980. It was at this time, though, that the growth really began in earnest. By 2000, the diesel-powered passenger car accounted for 32% of new car sales, growing to 54% in just seven years.
"Projecting up to 2012 we expect the passenger car diesel business will continue to grow at around 6% a year," says Alex Ismail, President, Global Passenger Vehicles, Honeywell Turbo Technologies. However, it does not stop there, as he anticipates spectacular growth in the turbocharged gasoline engine market with a projected 20% annual growth. "The figures have to be put into context, though," he states, "as that 6% is on 30 million turbocharged diesel units a year, which therefore equates to around 1.8 million units. When we talk about turbocharged gasoline engines, the 20% is on 2.5 million units, which means around half a million units."
Driving this new-found popularity is the turbocharger's new role as the device that is helping carmakers not only to downsize their engines, but also making them smaller, lighter and more fuel efficient. "As you look around the world there are increasingly stringent fuel economy and emissions requirements that the manufacturers have to meet with their new cars," says Ismail, "so the way the turbocharger should be seen is not as a component but as a legislative gain. "The automakers are resorting to downsizing their engines, but at the same time they need to cope with the increasing weight of the vehicle due to their safety requirements, increased passenger refinement and the onboard electronics. The typical scenario is one where the driver wants to be more environmentally friendly, but not at the expense of refinement, performance and overall drivability. The only way the auto manufacturers can deal with that is to have a turbocharger at the centre of the engine which is why you see them becoming such critical devices as they help solve this complex equation."
Another benefit that the turbocharger brings, claims Ismail, is that it enables the automakers to differentiate their models across one platform. "What they do is to use one turbocharger on a single engine base to differentiate the horsepower range. For example, a high-end car might have a twin turbocharger and then as you progress down the model range, the level of technology content on the turbocharger will vary. For example, 10 years ago a typical 1.9-liter engine used three to four turbochargers covering gasoline and diesel. At that time, you would probably see just one turbocharger for gasoline and two or three covering the entire output range of the 1.9-liter. Today, the average is around eight to 10 turbochargers, which tells you that the complexity for a given engine displacement has increased quite a lot. This has occurred because it's a relatively easy way for the automakers to offer basically the same car and engine package with the differentiator being the performance level. For example, you might see 70-hp, 80-hp, 90-hp, 110-hp and 175-hp versions off the same 2.0-liter engine which the manufacturer can market as different models."
While the basic fundamentals of the turbocharger have changed very little in the 100 years of its existence, new demands are forcing the manufacturers to go back to basics. "Technology requirements are changing the turbo industry with more electronics and the necessity to operate at high temperatures under the hood," says Ismail. "The performance requirements are stretching the design to a point where we have more and more complex designs to deliver in terms of performance and packaging, but with less space under the hood, so it's becoming much more challenging for us." He adds, "It also means that we are doing a great deal of research, leveraging our aerospace technology and developing new high-temperature materials for the turbine housing and other turbocharger applications. We are also working on new bearings technology using our aerospace knowledge. Another thing we are aggressively working on is an oil-less turbocharger that we have leveraged out of aerospace technology although we don't have any applications as yet."
Another area Honeywell is working on is better integration with the control systems. "We are putting more sensors and having a more sophisticated interaction with the ECU and are also seeing an evolution of more sophisticated electric driven actuation systems," says Ismael. "We are also reinventing the variable geometry turbocharger for gasoline application that we're going to launch in two or three years."
Ismail is confident that the turbocharger business has a very bright future, not just because of its uptake in the gasoline engine market, but also in the diesel one, as well. "Gasoline is clearly becoming the vehicle of growth with the GDI engine and turbochargers delivering outstanding fuel economy," says Ismail, "and they are going to catch up with the drivability of diesel engines as we know them in Europe. However, the foundation of this business being driven by turbocharged diesel engines remains extremely strong around the world. While Europe is reaching maturity as far as market penetration is concerned, there is strong growth in North America, China and India."