BRENTWOOD, February 22, 2001 -- The very latest second-generation common rail diesel technology is about to become production reality for Ford.
The class-leading Ford Focus spearheads a progressive introduction of sophisticated second-generation, common rail diesel engine technology into the core of Ford's vehicle range. This advanced technology offers highly flexible, extremely accurate, high-pressure fuel injection for outstanding refinement, performance, fuel economy and emissions capability.
Its introduction places Ford among the first manufacturers to offer this advanced level of diesel technology. The customer benefits - led by the engine's smooth, quiet operation and significantly increased torque - are immediately noticeable. Ford Focus TDCi models will go on sale progressively in European markets, starting in Summer 2001.
"With second-generation common rail diesel engine technology, we can deliver new levels of performance, refinement and efficiency for our customers," said Martin Leach, vice president, product development, Ford of Europe. "The Focus TDCi has to be driven to be fully appreciated for the giant step in driving quality it provides."
Ford did not introduce first generation common rail technology, opting instead to develop its direct injection system for the Ford Mondeo. Ford engineers rated the first-generation common rail applications on par with two other high-performance diesel systems - electronic unit injection and high-pressure rotary pump injector systems with pilot injection.
"Many people asked us why we have not adopted common rail technology earlier", said Leach. "Our analysis and tests indicated that, while promising, first-generation systems did not offer the levels of fuel-system pressure and injection precision to justify their premium price. We believe the new second-generation technology is more affordable and highly robust."
Due to first-generation common rail's technical limitations, Ford opted for a smart solution for its most recent diesel engine introduction - the new Duratorq Di engine family for the Ford Mondeo.
Engineers developed a traditional injection system but with unique capabilities. The high-pressure Bosch VP-44 rotary fuel pump powers Duratorq Di with pilot injection for added refinement, plus a unique transient 'overboost' feature for noticeably enhanced performance.
Versions of the new Duratorq Di engine for passenger cars were introduced in 2000 to power the all-new Ford Mondeo, with impressive results compared to diesels equipped with traditional axial fuel pumps.
Martin Leach hinted recently that more exciting diesel technology would be coming from Ford. The new Focus TDCi is the first to be launched, and demonstrates Ford's commitment to offering premium common rail options in the heart of its vehicle range.
The 115-PS Ford Duratorq TDCi engine for the Focus takes Ford to the next level in diesel technology, but it also incorporates the unique transient 'overboost' technology pioneered by the Mondeo Duratorq Di.
With transient 'overboost', the engine delivers performance enhancement when the driver demands it for acceleration, especially in fourth and fifth gears. This transient 'overboost' technology is the result of sophisticated electronic calibration of the engine's operation, to take full advantage of turbo boost.
A TDCi option for the Mondeo range will be launched later in 2001, but the story is still far from over.
"We've committed to trebling our product launch pace over the next five years as we transform our European business," Leach explained. "But Ford is also making an equally aggressive push in diesel engine development. The new Focus TDCi common rail engine is merely the first in a long stream of upcoming Ford diesel technology advancements."
Diesel Popularity Growing
It takes just one look at fuel prices at the pump to see why the popularity of diesel engines more than doubled in the decade between 1990 and 2000. The price advantage of diesel fuel, plus the additional fuel economy benefits of modern diesel-engined vehicles, has contributed to diesel engines accounting for nearly 35 per cent of car sales across the (heavily taxed) European region. That figure is expected to approach 40 percent by 2005, while in the UK alone we anticipate diesel sales to account for 30 percent of the market by 2005 - an increase of 16 percent.
The phenomenal growth of diesel engines has come despite the stigma of noise and emissions associated with diesels of the past.
"New diesel technology has changed this dramatically," said Mark Eden, the Ford engineering manager responsible for the Duratorq diesel engine range. "Now, our second-generation common rail engines go further still, and are designed to be so smooth, quiet and smoke-free, that they have characteristics more akin to petrol engines."
Increasing customer demands for performance and refined diesel operation, and societal demands for greater fuel economy and emissions capability have driven this ongoing development of the common rail diesel engine.
How Common Rail Systems Work
Common rail technology takes its name from the architecture of the engine's fuel injection system. Unlike conventional diesels, which rely on the fuel pump to deliver bursts of pressurised fuel to the individual cylinders through mechanical injectors, common rail systems employ a high-pressure reservoir - the rail - that delivers fuel to the cylinders via electric solenoid-actuated injectors.
The common rail system uses a high-output rotary fuel pump to maintain fuel pressure in the reservoir. Its performance is robust and precise, and largely independent of engine speed - a critical advantage over traditional rotary-pump applications. This allows the electronic control of fuel injection events with a high degree of accuracy.
"Precision is at the heart of the capabilities of second-generation common rail to provide new levels of diesel engine refinement, boosted power, better fuel economy and emissions capability," Eden said. "With this new technology, we can finely calibrate the combustion process to further eliminate much of the traditional harshness associated with diesels, while providing significant power improvements for the customer."
How precise is common rail? The high accuracy of the injection event that is attainable with pressure-balanced solenoid injectors means that engineers can tailor each cylinder's combustion, using a technique called pilot injection. This involves the injection of a small pulse of fuel prior to the main injection pulse.
The timing of the pilot injections can be calibrated for various operating conditions. The amount of fuel injected during a pilot injection moment can also be adjusted, down to an accuracy of approximately one cubic millimetre of fuel.
Timed carefully prior to the main burst of fuel being injected into the cylinder, pilot injection helps to initiate a more controlled combustion event. This allows for more smooth and efficient burning of the larger main-injection fuel dose immediately thereafter.
Due to the precision of common rail systems with the advent of second-generation technology, calibration mapping can precisely vary the timing and quantity of the pilot as well as the main injection.
The objective is to continuously refine the diesel combustion process over the full spectrum of operating conditions - and to extend the possibilities for improved performance, economy, smoothness and emissions capability.
It is in this infinitesimal zone of accuracy that second-generation common rail technology's true benefits are found. And it is in this zone that research is still going on in search of even cleaner diesel engines for the future.
Debut of Second-Generation Common Rail Technology
The Ford introduction marks the debut of new second-generation common rail technology from Delphi Automotive Systems, the Multec™ DCR 1400. The system offers several advantages over first-generation systems, including higher system pressure, ultra-compact fast-acting solenoid injectors, inlet flow metering and accelerometer pilot control (APC) for durable service life.
The second-generation common rail systems feature the following primary components:
* A dual-stage vane-cell fuel pump that transfers fuel from the fuel tank under low pressure and delivers very high pressures.
* An inlet metering valve measures the precise amount of fuel to be pressurised in the common rail, based on operating demands. This unique technology eliminates the need for fuel cooling and contributes to better fuel economy.
* The common rail, a thick-walled reservoir for highly pressurised fuel to feed to the injectors. The common rail is spherically shaped in the Ford Focus TDCi due mainly to engine bay packaging requirements. The rail has a separate outlet to feed each cylinder's injector. It is also fitted with a fuel pressure sensor, one of many electronic sensors that help the system optimise fuel injection performance under varying operating conditions.
* High-pressure fuel pipes, which connect the high-pressure pump, common rail and individual injectors. The pipes have an outside diameter of 6.0 mm and an inside diameter of 2.4 mm.
* Slim, six-hole pressure-balanced solenoid-actuated fuel injectors produced according to strict manufacturing tolerances far smaller than the width of a human hair. The tiny moving masses of the control valves have made it possible to achieve a rapid switching time of 0.3 milliseconds, which is the speed required for the system to react rapidly and precisely to changing operating conditions. This light and balanced valve allows the use of an ultra-compact solenoid, located in the middle of the injector body closer to the nozzle needle than other common rail systems. The injector's package-efficient design has a maximum diameter of 17 mm, making it an ideal design for installation in both two-valve and four-valve heads.
* Each injector - whose operating characteristics are tested during manufacture - is labelled with a matrix code, a technique called individual injector characterisation. When the injector is installed on the engine, its matrix-coded characteristics are optically scanned and programmed into engine control unit (ECU). This helps to customise the electric drive pulse timing and duration for cylinder for optimal engine operation.
* Fuel filter with an integral control valve that closes the return to the fuel tank at low temperatures, which warms the fuel in the fuel filter for optimal operation. The fuel filter has a water collection chamber, which can be emptied via a drain plug on the underside.
* The Injector Driver Module (IDM) is the computer brain behind the finely calibrated common rail fuel injection system. The IDM works in tandem with the Ford EEC-V engine management system.
* An array of engine management sensors feed information to the EEC-V engine management system and the IDM. These include:
- Fuel metering valve
- Camshaft position sensor
- Fuel pressure sensor
- Fuel temperature sensor
- Crankshaft position sensor
- Boost air temperature sensor
- Barometric pressure sensor
- Cylinder head temperature sensor
- Manifold absolute pressure sensor
- Mass air flow sensor
- Accelerator pedal position sensor
- Clutch pedal position switch
- Brake pedal position switch
An engine that "listens" for better sound quality
The new Ford second-generation common rail engines have the unique ability to "hear" their own operating characteristics. This ability to eavesdrop on the sound of their operation - a noise reduction technology called accelerometer pilot control - contributes to the Ford TDCi-equipped vehicle's outstandingly quiet, smooth running.
At the core of this capability is an accelerometer knock sensor mounted on the cylinder block between cylinders 2 and 3. This piezo electric sensor detects vibrations of the cylinder block caused by combustion, and signals these vibrations to the IDM.
It senses increased vibrations when pilot injection quantities are unfavourable, and alerts the IDM to adjust the quantity of pilot injections until a nominal operating sound can be restored.
Accelerometer pilot control takes into account minute differences that can occur over time with the engine's individual injectors. It assures optimal control of the pilot injection throughout the life of the engine.
This exclusive noise-reduction technology adds to the refinement that is inherent in a well-engineered common rail system.
Sound quality is one of the major benefits of second-generation common rail systems. The greater the accuracy of the calibration of the pilot quantity and timing at each injection, the better the results in terms of reducing the harshness that long has been considered the legacy of the diesel engine.
The harshness of the conventional diesel engine combustion process is one of the stigmas that have prevented diesel technology from reaching premium levels of refinement - until the advent of common rail systems. This is because conventional diesel combustion has an inherent sharp rise in cylinder pressure that creates a jarring clatter and rough characteristics. With the precise calibration possible using common rail technology, the diesel engine can achieve a far smoother bell curve of cylinder pressure. The result is easier on the senses.
For engineers specialising in the noise, vibration and harshness (NVH) of diesel-powered vehicles, common rail technology is a dream come true.
"Common rail is a big step forward," said Frank Foehner of Ford's Cologne, Germany, Acoustic Centre. "With diesel NVH, we are constantly working to achieve linearity of sound levels. Linearity means that as the engine speed increases, as the load on the engine increases, the sound and vibration of the engine rises predictably, steadily and smoothly. Conventional diesel engines just can't achieve that linearity, and that makes our job tougher.
"With common rail, we can really focus on the fine details that give our diesel customers the same kind of refinement that owners of petrol-engine vehicles expect," Foehner said.
TDCi -- the badge of advanced diesel engine technology
Ford vehicles bearing a TDCi badge are now the tangible results of Ford's move to the forefront of diesel injection technology.
The badge - a contemporary, crisp-edged rectangle bearing the TDCi nomenclature (TD for turbo diesel in black lettering, Ci for second-generation common rail injection highlighted in bold, red letters) - is the discreet symbol of precision diesel injection technology at the heart of the vehicle and the refined performance characteristics that it delivers.
"The discretion of the badge should appeal especially to customers for whom a premium diesel engine is attractive," said Ian McAllister, chairman and managing director, Ford Motor Company Limited. "For these diesel customers, there is a deep understanding of the excellence that this technology represents, especially as part of the overall package of a great vehicle like the Ford Focus. To them, common rail technology is really the icing on the cake."