Continuous optimization for greater efficiency
Press Release [DOC; 44 KB]
Stuttgart, Germany, September 2010—Engine components and systems such as pistons, piston rings and pins, connecting rods, and the valve train form part of MAHLE's core competencies. To achieve even greater efficiency and environmental compatibility, they undergo a process of continuous optimization.
Growing trends toward downsizing and tighter exhaust gas limits are resulting in higher pressures and temperatures in combustion engines. Materials and designs must therefore be adapted to meet these increasing requirements.
For aluminum pistons, for instance, MAHLE relies on the new M174+ alloy, which offers even better strength values at higher temperatures and alternating thermal loads.
With the Advanced Diesel Casting method, MAHLE is able to achieve an extremely fine microstructure over large areas by quickly cooling off the blank after casting. Local remelting of the bowl rim also produces an extremely fine microstructure locally due to the quick cool-off. In both cases, the microstructure has less tendency to crack, thereby increasing the service life of the pistons.
For commercial vehicle engines in the upper power class, however, locally optimized aluminum pistons are no longer enough. With its FERROTHERM®, MONOTHERM®, MonoWeld,® and MonoXcomp® steel pistons, MAHLE offers custom solutions to meet all demands.
For piston rings, MAHLE offers a Nano-Bor coating that ensures significantly less wear. As for connecting rods, MAHLE has developed a forging process, which allows a weight reduction of up to 25% and a significant reduction in the piston side force. Less friction and wear on the end bore and piston pin is achieved by applying a surface coating in these areas.
In terms of bearings, MAHLE is stepping up its research into new materials for the bearing shell. One example is a high-strength aluminum alloy with a polymer coating, which contains aluminum particles and solid lubricant. This combination features outstanding wear and seizure resistance, making it ideally suited for stop-start systems and hybrid drives.
Lighter crankshafts undergo greater deflection during operation. In response to this, MAHLE has come up with a profiled bearing design featuring a camber of approximately ten micrometers. These compensate for the shaft deflection at the bearing edges and thus minimize the edgewise supporting contact and wear, and bearing friction.
With the controlled pendulum-slider oil pump, MAHLE has developed a highly efficient, patented technology. Depending on the control strategy and driving cycle, the use of this oil pump alone can reduce fuel consumption and with it vehicle CO2 emissions by 3–4%. This also holds true for large-volume engines that are operated at low engine loads or that have a higher oil pressure requirement—like heavy-duty diesel engines. This innovative oil pump operates on the principle of volume-flow control, meaning that it always generates pressure and volume flow as needed, thus minimizing the pumping capacity required. The control strategy is based on the control pressure, which is sampled either at the pump outlet or in the oil circuit. Additional switching or control valves can then be used to achieve multistage or even fully variable control of the oil pressure and oil rate.
Additional advantages of the pendulum-slider oil pump include:
- Ability to withstand dirt and abrasive particles
- Less wear, hence continuously high efficiency
- Variable delivery pressure and displacement volume, which allow the pump to be used in a wide range of applications
- Speed-resistance of up to 14,000 revolutions per minute, making it possible to drive the pump via the crankshaft or balancer shaft
- Cost advantages compared to controlled vane pumps or gear pumps
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. The newly formed Industry business unit bundles the MAHLE Group's industrial activities. These include the areas of large engines, industrial filtration, as well as cooling and air-conditioning systems.
In 2009, the MAHLE Group generated sales of approximately EUR 3.9 billion; around 43,000 employees work at over 100 production plants and eight research and development centers.
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High-strength steel pistons are used for commercial vehicle engines in the upper power class. With the two-part FERROTHERM® piston type, MAHLE has set a global standard.
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In order to meet the requirements of commercial vehicle engines in the upper power class, MAHLE developed the single-piece forged MONOTHERM® piston.
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Since thermal requirements are poised to increase more and more in the future, the engineers at MAHLE have further improved cooling efficiency with the friction-welded MonoWeld® pistons.
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Commercial vehicle engines for future emissions standards require pistons that will stand up to extreme thermal stresses. MonoXcomp® pistons are tailor-made for such an application profile, thanks to their central screw connection and double cooling cavity.
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PCU for commercial vehicles
These detail innovations aside, MAHLE's foremost objective remains a comprehensive optimization of the power cell unit (PCU). The PCU consists of a piston with rings and pin, a cylinder liner, and connecting rod with bearings. Customers can be confident they will receive an optimally harmonized package that will best meet their needs.
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Connecting rod for commercial vehicles
As for commercial vehicle connecting rods, MAHLE is working on an optimized forging process, which allows a weight reduction of up to 25% and a significant reduction in the piston side force. Sound design for the end bores improves the lubrication properties.
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Pendulum-slider oil pump
With the controlled pendulum-slider oil pump, MAHLE has developed a highly efficient, patented technology. Depending on the control strategy and driving cycle, the use of this oil pump alone can reduce fuel consumption and with it vehicle CO2 emissions by three to four percent.
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Pendulum-slider oil pump
In a simple control strategy, the delivery rate of the pendulum-slider oil pump is controlled via the control pressure, which is sampled either at the pump outlet or in the oil circuit. Additional switching or control valves can be used to achieve multistage or even fully variable control of the oil pressure and oil rate.
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Pendulum-slider oil pump
In MAHLE's patented pendulum-slider oil pump, a pendulum is supported in an outer rotor in such a way that it can be rotated and is guided by means of an inner rotor positioned off-center with respect to the outer rotor. As a result of this configuration, between every two pendulums a feed cell is created, forming a highly leak-proof entity.