Assembled camshaft for commercial vehicles goes into series production
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Assembled camshaft for commercial vehicles
The assembled camshaft for commercial vehicles from MAHLE achieves a weight advantage of around 30 percent in its first series application
Hanover, September 2012 – The valve train in a combustion engine is continuously subjected to high mechanical loads. Advances in reducing friction and weight have therefore had a direct influence on the efficiency of the entire engine, and thus reduced fuel consumption and CO2 emissions. MAHLE's assembled camshaft achieves a weight advantage of around 30 percent in its first series application.
Cast iron camshafts have long been used for light commercial vehicles, while medium to heavy commercial vehicles have resorted to forged steel camshafts. These technologies require relatively high tooling costs, which are very disadvantageous relative to passenger cars due to the low production quantities. Assembled camshafts allow higher contact pressure between the cam lobe and cam follower in comparison to cast camshafts, and offer significant weight advantages over steel camshafts made from solid material or raw forgings. The great design flexibility of the individual assembled components also provides cost advantages with respect to materials and design. For example, very durable cam lobes are made of roller bearing steel and then inductively hardened, while the drive input and output elements can be made of less expensive materials, as needed.
The MAHLE production method for assembled camshafts provides optimal conditions for flexible manufacturing. Using a thermal shrink-fit method, parts such as cam lobes, pulse generator wheels, and driving and output elements are joined to precision steel tubes having a high degree of torsional stiffness and flexural strength. The purely elastic shrink-fit composite guarantees a consistently high interference fit of the joined components over the entire service life of two million kilometers required for commercial vehicle engines. Assembled camshafts that are not produced with the MAHLE manufacturing process, but by means of plastic deformation at the joint seating surfaces, demonstrate an aging effect; the joint becomes weaker over the service life. MAHLE has produced assembled commercial vehicle camshafts under near-series conditions and performed successful endurance tests. With the series launch that is currently underway at a well-known manufacturer in Europe, the first assembled camshafts for commercial vehicles from MAHLE will see large numbers built in series production. In this series design, the camshaft achieves weight savings of about 30 percent.
In the course of rising requirements for modern engines, additional potential gains are being evaluated for assembled camshafts, and the component is under ongoing development. One possibility is to use a rolling bearing in place of the hydrodynamic plain bearing that is typical for camshafts. The resulting reduction in frictional loss and optimized oil balance further contributes to optimizing CO2 and reducing fuel consumption in the powertrain. MAHLE is currently investigating the potential of this technology for use in commercial vehicles.
Assembled camshafts for commercial vehicles from MAHLE enable modern commercial vehicle engines to fulfill increasing requirements related to service life at a low cost, while simultaneously reducing weight and optimizing fuel consumption. A clear trend toward the use of assembled camshafts can be seen in the development of future commercial vehicle engines.
The MAHLE Group is one of the 30 largest companies in the automotive supply industry worldwide. With its two business units Engine Systems and Components and Filtration and Engine Peripherals, MAHLE ranks among the top three systems suppliers worldwide for piston systems, cylinder components, as well as valve train, air management, and liquid management systems. MAHLE’s industrial activities are combined in the Industry business unit. These include the areas of large engines, industrial filtration, as well as cooling and air conditioning systems. The Aftermarket business unit serves the independent spare parts market with MAHLE products in OE quality. In 2011, the MAHLE Group generated sales of approximately EUR 6 billion; around 49,000 employees work at over 100 production plants and eight research and development centers.
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