Panning for black gold

(Published November 2007) The car oil pan, or sump, is perhaps the last large volume component around the engine that has not yet been substituted by plastics. Now the time is ripe for change, says Mann+Hummel innovation manager Thomas Jessberger.

M&H’s all-plastic car sump designs weigh typically 900g, a considerable weight saving over the 1.5kg typical weight of conventional hybrid designs or the 2.2kg all-aluminium equivalent. And an injection moulded plastic sump provides better opportunities for integration of functions such as the oil module, filter, centrifuge, level measurement, screen, ducting and sensors.

M&H announced at this year’s IAA 2007 automotive fair in Frankfurt that it will have a thermoplastic oil sump in series production for an unidentified 2009 car model, the result of a project it secured last year.

“If all passenger cars in Germany were fitted with lightweight plastic oil pans from M&H, this would reduce CO2 emissions by 65,000 tonnes a year,” Jessberger estimates.

M&H sees two basic design approaches to plastics car sumps – a hybrid metal/plastic solution capable of supporting gears or an all-plastic version functioning more as a cover. The trend in the car industry, however, is toward the more simple types, says Jessberger.

Injection moulded oil pans have already been proven in the truck arena, with a 39-litre thermoplastic oil sump moulded in BASF’s 35% glass fibre reinforced easy-flow, impact and heat stabilised polyamide 66 grade Ultramid A3WG7 in service on the Mercedes-Benz Actros BR500 truck since late 2003.

BASF engineering thermoplastics sales manager Willi Bartholomeyzik says the use of plastics allowed a 30% increase in sump volume which meant service intervals could be increased from 100,000 to 150,000 km.

Bartholomeyzik says the same high stiffness required in truck designs is not required in car sumps, even though the housing may have to bear the full weight when an engine is taken out and put on the ground. However, there are other challenges.

“A car engine block is like a Swiss cheese and there are static functions above and below involving high static and dynamic forces. A lorry sump is simply like a blister built into a very stable structure,” he says.

BASF has performed 5,000 hour 160°C hot oil exposure and stone impact tests on oil pans injection moulded in its Ultramid A3WG7 Q17 oil sump grade and incorporated these in a computer simulation program.

Application development manager Thomas Hohenstein says the material is more than suitable for 100,000 km of driving.

www.basf.com

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The timeline

Oil sump housings have traditionally been made in cast metal or more recently thermosetting plastic such as SMC. The first developments in thermoplastics were begun in 1977, says Mann+Hummel innovation manager Thomas Jessberger, leading to DuPont’s first module concept in 1985.

M+H developed and tested thermoplastic sumps with Audi in 1996 on a V6 engine. In the same year, German moulder Kunststoffwerk Sachsen (KTSN), which had been working with Mercedes-Benz on a cooperative cylinder head cover development, started to explore the feasibility of a thermoplastics oil pan.

KTSN managing director Dr Erich Liehr says Mercedes-Benz was looking for a more compact, lighter weight solution with reduced noise emission, combined with a degree of part integration that metal and thermosetting plastic sumps had been unable to provide.

However, it was not until the end of 2003 that the first series application for a thermoplastic oil sump got underway on the Mercedes-Benz Actros BR500 truck. The Mercedes-Benz application won the SPE Central Europe 2003 automotive grand innovation award for KTSN and partners BASF, Engel and mouldmaker Presswerkzeugbau Gro?dubrau.