April 2005
 

Rheinmetall's tradition of automotive excellence

The variable intake manifold saves the plant in Nettetal

 
In February 1986, the 77th year of operations for tradition-steeped Pierburg, Rheinmetall Berlin AG took over the stake held by the Pierburg family in the largest German manufacturer of carburetors. This was a crossroads in the company's history, because despite the dominant influence of Bosch, Pierburg had remained a family enterprise up to that point, which was headed by a member of the family, Jürgen Pierburg.

The prelude to the takeover was a dispute between Bosch and Siemens, which had even caused a considerable stir in the German daily newspapers, business and trade publications. Bosch had succeeded over a number of years in applying its 20-percent stake to exercise control over Pierburg, using the company as its de facto workshop for Bosch's electronic injection systems. In-house developments at Pierburg, which would have been entirely feasible with the expertise present, were consistently suppressed.

As the February 13, 1986, issue of the Frankfurter Allgemeine Zeitung noted, Bosch was engaged in "jealous" efforts to keep competitors like Pierburg "out of the lucrative field of complex control electronics and precision metal parts for injection systems." Bosch CEO Dr. Lutz Merkle would have preferred to take over Pierburg entirely and digest the organization into his own group of companies, but this was prevented by the ruling of the German Federal Cartel Office.

Jürgen Pierburg himself would have much preferred to work with Siemens. This was because the electronics specialist in Munich was developing its own modern injection systems in competition with Bosch, which would have fit well with existing developments at Pierburg. However, this was prevented by Bosch by its insistence on applying a contractual first right of purchase, although the Stuttgart-based company was unable to exercise that option itself.
 

Made of cast steel, aluminum, magnesium or plastic, air control components in engine systems comprise a core field of expertise at Pierburg GmbH. The first new products in 1990 from the Nettetal plant included a variable length intake manifold for Audi (left); the intake manifold for a V6 engine (right) was first presented at IAA in 1997.

 
Dr. Hans U. Brauner had previously worked for Merkle at Bosch, and Merkle now thought of him as a new industrial partner for Pierburg who—as Bosch assumed—could be controlled without difficulty in matters of injection systems.

Brauner had meanwhile become CEO of Rheinmetall Berlin AG. And since the Rheinmetall group had just failed to obtain the approval of the Cartel Office to acquire WMF AG, Pierburg and the automotive sector appeared to be a suitable alternative for the lost opportunity in the area of consumer goods. Rheinmetall took over the family shares in Pierburg (80 percent of the company); Jürgen Pierburg, the Management Board Chairman, withdrew from the public arena.

Before the takeover of Pierburg, it was already clear to the Executive Board of Rheinmetall that the carburetor was on the way out. Thus in the report to the Supervisory Board regarding the acquisition of the Pierburg group, in which the expected revenue share for carburetors was stated as 32 percent for 1990 and 10 percent for 1995, there was already talk of a new plan for manufacturing at Pierburg.

The electronically controlled "Ecotronic" carburetor, jointly developed by Pierburg and Bosch, which was supplied to Daimler-Benz for the first time as the takeover occurred, was seen only as a compromise solution on the road to electronically controlled fuel injection. However, Bosch had a 90-percent share of this market, which it was not willing to cede to Pierburg or Rheinmetall.
 

Pierburg developed an innovative pneumatic combination valve (left) for a secondary air injection system introduced in 1994, with both switch-off and non-return functions. The electric regulating throttle for diesel applications (right) serves quite different purposes. Together with the EGR valve it provides a significant reduction in harmful emissions in the air.

 
"A crucial element of the agreements with Bosch is therefore the obligation of Bosch to make all the necessary patent licenses available to Pierburg on appropriate terms." Bosch did not meet the expectations of Rheinmetall's Executive Board prior to the acquisition of Pierburg nearly as much as the engineers at Pierburg wanted.

In addition to that, newly developed "Ecojet S" and "Ecojet M" injection systems were unmarketable to the automobile manufacturers. The reason for this: Mercedes, VW, Opel and the remaining manufacturers already purchased similar systems from Bosch, the market leader. Why should they have to rely on a smaller manufacturer with no reputation in this market, whose patent rights were only second-hand—namely from Bosch?

Stockholders at the August 1988 annual meeting of Rheinmetall in Berlin posed the obvious question: "Do you still believe that Pierburg can continue to be a profitable contributor to the company in the years to come?" The stockholders knew that Rheinmetall was not at fault for the difficult situation in 1988 and 1989, but rather "ten years of rudderless management" and 16 years of frustrated development. When Rheinmetall acquired the remaining 20 percent from Bosch in 1989, it was already too late for the electronic injection. Only Siemens was able to compete with Bosch and develop an injection system jointly with BMW for the new Series 3.

As early as 1979 there was an international agreement "regarding extensive cross-border air pollution in connection with the control of emissions from nitrogen oxides or its cross-border flow patterns". On this basis, Germany and other European governments signed a protocol in 1988 that required them "to implement a reduction of the national nitrogen oxide emissions by 30 percent as fast as possible and at the latest by 1998."

The German federal and state environmental ministers then agreed in April 1989, at the initiative of Klaus Töpfer, then the German Minister for the Environment, to make a computer-controlled three-way catalytic converter mandatory equipment for new vehicles—which practically eliminated the carburetor, Pierburg's main product.
 

The finest in high technology: under the hood of the BMW Series 6 coupé lies the ultra-modern, fully variable intake manifold from the automotive supplier Pierburg in Neuss. (Photo: BMW Group)

 
This development was of course no surprise to Pierburg, but the early timing of the "Töpfer Initiative" was unexpected. Pierburg had planned to increase its cash flow for another two or three years in order to convert its production program gradually. Now, altogether 1,450 employees in Nettetal were suddenly threatened by the shutdown of their plant.

While real-estate agents were already assessing the property in Nettetal to sell it, a significant number of employees had been laid off, the Rheinmetall Supervisory Board was informed of the plant's impending closure and the remaining workforce saw no future for the entire Pierburg company, dramatic events with the company's own new developments resulted in a turnaround, surprising the market. As early as 1989, an electric fuel pump developed for VW especially for injection engines was put into production. It also won over Audi, BMW and Mercedes as customers.
 

Pierburg introduced an air mass sensor with pulse recognition for the first time at the International Motor Show (IAA) in Frankfurt am Main in 1997. It was equipped with a new semiconductor sensor element and offered higher precision, greater flexibility and more functions than conventional air mass sensors available until then.

 
Finally, the breakthrough for the Nettetal plant was achieved by the intake manifold. In November of 1990, Pierburg and Audi presented a jointly developed variable intake manifold as a component of the V6 engine in the new Audi 100, which ensured better engine performance at higher as well as lower speeds. In the Audi 100 "2.8E" and "Quattro" models, this variable intake manifold made of gray cast iron was pre-assembled as a module for the very first time, complete with throttle body, exhaust gas recirculation and idle speed adjustment, tested and delivered ready for installation.

While in fiscal year 1990, sales of carburetors declined to 30 percent, thus falling 15 percent short of planned figures, fuel pumps, vane pumps, electrical cut-off valves and intake manifolds brought Pierburg back into the black with surprising speed. Furthermore, the exhaust measuring system AMA 2000 became a business success of unexpected dimensions.

In 1991, electric fuel pump production was expanded at the Neuss plant. In the fall of the same year, series production of throttle bodies began at Nettetal, and a Chinese delegation came to inspect the carburetor production and testing systems in order to purchase them and use them in China.

An innovative exhaust gas recirculation valve (EGR) by Pierburg was integrated in the new BMW Series 5 and Series 3 diesel cars as well as in the eleven model of the then-current Mercedes-Benz diesel series equipped with exhaust cleaning systems. In addition, the company supplied the first membrane vacuum pumps for a special exhaust gas extraction and recirculation system for the uptake and recirculation of gases developing in the tank during filling.

The turnaround was finally documented in a management decision dated April 16, 1991: The Nettetal plant remained open. From that point on, Pierburg, which had quietly been pronounced dead, was on the road to recovery and became one of the key international suppliers of components and modules for many engine functions.

In addition to the development stations for vacuum pumps, intake manifolds made of aluminum, magnesium and synthetic materials, catalyst converter startup heaters, auxiliary air pumps, air mass sensor or high pressure side channel pumps, the acquisition of VEM-Elektro-Kleinmotoren and Gerätewerk in Hartha in Saxony in 1992 also contributed to this success. The Hartha subsidiary became the fourth Pierburg location, alongside Neuss, Nettetal, and Berlin. Moreover, the opening of a new plant in Fountain Inn, near Greenville, South Carolina, on October 4, 1996 was a key milestone in the expansion to the US market and the internationalization of Pierburg.

This positive development, reflected in rising sales and profits, finally achieved its summit with the acquisition by Rheinmetall of a majority share in Kolbenschmidt AG in Neckarsulm, Germany and the subsequent merger of both automotive companies to form Kolbenschmidt Pierburg AG.
 

On the road with state-of-the-art intake manifold technology from Pierburg GmbH (from left to right): the PT Cruiser from DaimlerChrysler, the Mercedes SL 500, the BMW Series 7 sedan and—last but not least—the VW Phaeton. (Photos: DaimlerChrysler, BMW Group, Volkswagen)
 

 
State-of-the-art intake manifold technology

 
Since the beginning of the 1990s, numerous components for air supply or emission reduction have replaced the carburetor at Pierburg. These include the electronic cut-off valve, the air mass sensor, new generations of throttle bodies or secondary air valves and several pump types.

The intake manifold is in fact only one of the products that have ensured the survival of the Neuss-based automotive company since 1990, but it has symbolic value: the rescue of the Nettetal plant is closely associated with the new development of the variable intake manifold.

What is a variable intake manifold? In general, an intake manifold is understood to be piping that uses negative pressure to transport liquids or gases. In the engine of a gasoline-powered vehicle with selective injection, the variable intake manifold ensures optimal air feed to the combustion chamber. It enables higher engine performance, optimal fuel consumption and lower emissions at all speeds by regulating the air supply and distributing it evenly to all cylinders.

A key feature of Pierburg's variable intake manifold is that it is delivered as a module. The throttle body, EGR valve, and idle speed adjustment or control valve are installed on the intake manifold at the factory and supplied as a complete assembly to automobile manufacturers.

The first variable length intake manifold supplied by Pierburg for a German production series vehicle was a joint effort of Pierburg and Audi for the V6 engines of the Audi 100 "2.8E" and "Quattro" models. As a one of the many ongoing developments, Pierburg produced the intake manifold used for the OPEL 1.8- and 2.0-liter engines which went into series production in 1995.

Here the company used a new casting shell technology for the first time. Since the new foundry at the Nettetal plant went into operation in October 1995, Pierburg has enjoyed the advantages of pressure die-casting technology: low weight, smooth and low-loss channel walls and elimination of most of the downstream machining work combine to reduce production costs and improve efficiency. Super-light intake manifolds are produced in this process using magnesium alloys, allowing wall thicknesses of 1.5 millimeters to be achieved. This was presented for the first time at the Frankfurt Motor Show (IAA) in September 1995.

Another milestone was the V8 variable length intake manifold for the Audi V8 engine, presented in 1999: it was the first magnesium intake manifold manufactured with thin-wall pressure die-casting technology that featured a three-step length selection, achieving higher torque at lower RPM. This enabled fuel consumption and emission values to be reduced significantly once again.

The latest development is an integrated intake manifold module, which combines the intake manifold for the air supply and the exhaust gas recirculation (EGR). Pierburg is the first supplier of this technology worldwide, presenting it at the IAA in Frankfurt in 2003.

The Nettetal foundry manufactures intake manifolds according to customer specifications. These may be sand-cast, or produced in chill molds or by pressure-die casting; they may be made of aluminum, magnesium or plastic. In all cases, weight and cost reduction are foremost considerations. The intake manifold manufactured since 1995 with heat-resistant plastic offers the same section shape options as pressure-cast units of magnesium and aluminum, with low weight and flow resistance.
 

With the Audi Quattro on the winners' rostrum

 
When back in 1990 Pierburg and Audi unveiled a jointly developed variable intake manifold for the new Audi 100 Quattro, this was not the first time that this car legend had taken on great significance for the long-established Pierburg company. In 1980—six years before Pierburg's takeover by Rheinmetall—the Pierburg Grand Prix was staged on the Nürburgring in the Eifel for the first time. The vehicles on the starting grid included an Audi Quattro—equipped with the CS race injection system supplied by Pierburg. The driver of that vehicle was the Swede Per Eklund, who took Audi and Pierburg to victory.
 

The Audi Quattro, a star on the world's great racing tracks for many years, is celebrating its 25th anniversary this year. Hannu Mikkola and his co-driver Arne Hertz drove to victory in an Audi Quattro A2 at the Acropolis Rally of 1984. (Photo: Audi AG)

 
The vehicle made its world debut at the 1980 Geneva motor show, immediately causing a sensation. It may not have been great looking, based as it was on the well-known Audi coupé with its characteristic angular body. However, this basis had been extensively reworked, chief external features being the "chubby cheeks," as the conspicuously widened fenders were known, and a striking front spoiler.

Under the front hood sat a five-cylinder engine with 2.1-liter displacement, which a turbocharger propelled to 147 kW or 200 HP. And the most important factor was that this vehicle, designed with the help of Ferdinand Piëch, co-owner of Porsche and subsequent CEO of Volkswagen AG, was the first German four-wheel drive passenger car—hence the name "quattro."

The Audi Quattro excited the public and the experts equally, being suitable for everyday use like a Polo and as fast as a Ferrari. It was a military vehicle which provided the inspiration for the new car. During winter car trials in Norway, Audi also tested the cross-country vehicle Iltis, produced in Ingolstadt, which was to replace the DKW Munga jeep used by the German armed forces. The developers established that its four-wheel drive provided an ideal solution to frequent car driving along winding roads. Ferdinand Piëch took up the idea of his test car driver in Norway, who is reported to have enthused to him: "A four-wheel drive car with more power than the 75-hp Iltis—that would be something!"
 

The first test drive of the newly developed vehicle took place in 1978. On the snow-covered Turracher Höhe in the Austrian Alps with its gradients of over 30 percent, where VW would test conventional vehicles only fitted with snow chains, the 4WD Audi with summer tires coped with even the steepest slopes effortlessly much to the amazement of the attending Volkswagen bosses. A further test in May of the same year in Ingolstadt, for the purpose of which a meadow with a steep slope was flooded with water by the fire brigade to produce the necessary slipperiness, also proved a complete triumph for the car.

It was therefore no surprise that this suitably equipped Quattro with its maximum speed of 220 km/h and able to accelerate from 0 to 100 km/h in 7.1 seconds entered the world of motor sport: Nürburgring, Monte Carlo, San Remo—the Audi Quattro was always in the running. All the experts were convinced that the four-wheel drive would provide benefits only on slippery surfaces. On the Nürburgring racetrack, it was Per Eklund, who took the Audi Quattro to victory in the Pierburg Grand Prix on a road route for the first time.

The first motocross racing team to be engaged by Audi was made up of the Finn Hannu Mikkola and his Swedish co-driver Arne Hertz, who celebrated a first racing victory in the Audi Quattro in Sweden in 1981. They were followed by Frenchwoman Michele Mouton accompanied by Fabrizia Pons from Italy as well as Stig Blomqvist and Björn Cederberg.

The later version, the Sportquattro, also achieved spectacular success on the world's racing tracks, including with the racing legend Walter Röhrl at the wheel and Christian Geistdörfer as co-driver, who came first in the St. Remo race in 1985—the last race in the Quattro, which won both the manufacturers' and drivers' world championships twice. This vehicle therefore managed to overtake even the hitherto leading Ford and Lancia makes.

With the turbocharged Quattro as its top model, Audi was soon offering four-wheel drive across its whole range, with many other manufacturers following suit. Very few vehicles, however, managed to combine the Audi Quattro's excellent performance, reliable technology and high safety standards. In addition, it was marketed not only as a racing car but also as a practical vehicle suitable for everyday use.

As the magazine 'autocar' once noted: "Getting into a normal car again is like stepping back into the past." However, neither the Urquattro nor the Sportquattro of 1983 became mass-produced models. Anyone seeking this superior driving experience had to shell out a substantial DM 50,000, with Audi demanding as much as DM 200,000 for the Sportquattro. It is no great surprise to learn that only 214 of these 206-hp vehicles were ever built.

By this time, however, Pierburg had withdrawn from the prestigious motor sport business again. In 1984, production of the CS race injection system was halted, and Audi's Sportquattro was equipped with a rival product.

For many motor sport enthusiasts Pierburg's withdrawal was a disappointment although the Neuss-based specialist had at least managed to outdo the until then dominant Italian competition. These successes were not based on the CS race injection system and the Audi Quattro alone, however. From 1967 onwards, it was Pierburg's technical service which won its customers' trust and high regard at the Nürburgring and Hockenheimring racing circuits.

The Italian engine builders of Alfa Romeo, Lancia, Ferrari or Matra, which equipped the sports models of their marques with special carburetors, may have dominated motor racing with their products but failed to provide any product support services at the racetracks and therefore gradually lost ground in the racing world. Moreover, Pierburg managed to gain great prestige in Formula V because the rules stipulated the use of original production parts for the very successful VW and Wankel NSU engines at that time in the Grand Torismo class, meaning for the VW engine Pierburg's relatively simply designed Solex carburettor.

The paths of the Audi Quattro and Pierburg crossed again years later not on the racing track but in everyday road traffic. A variable intake manifold from Nettetal was built into the four-wheel drive Audi 100 for the first time—thus opening a new chapter in Kolbenschmidt Pierburg AG's success story, which over the whole Rheinmetall-Automotive range has lasted to this day, up to and including the current Audi V 8. And it is a Quattro, of course.