Ludwigsburg/Frankfurt, September 12, 2017 – the pressure control valves of today which use elastomer membranes are not able to withstand aggressive chemicals. RobustPlus, a new material for pressure control valves from MANN+HUMMEL, now ensures high resistance to chemicals.
In particular with petrol engines in markets where the quality of the petrol can vary, malfunctioning pressure control valves cause quality problems in the automotive industry. The limited chemical resistance of elastomer membranes made from fluorosilicone rubber leads to increased and accelerated ageing. In combination with a mechanical load the risk of the formation of cracks increases. The consequences range from unsmooth running of the engine to a breakdown or oil leaks. Problems accumulate with engines with a low mileage and up to a mileage of 80,000 kilometers. Also solutions based on fluorosilicone rubber reinforced with fabric or the use of fluorosilicone rubber polymers are not really an alternative.
"The RobustPlus membrane sets new standards with regard to its chemical resistance and mechanical resilience", explains Lukas Bock, the responsible design engineer and project manager at MANN+HUMMEL.
Tested a million times
The developers at MANN+HUMMEL have now found a solution in the form of a new fully fluorinated polymer. This has passed the standard tests and has also demonstrated its almost universal chemical resistance and durability in an extended series of tests under conditions close to real driving conditions and even under over-severe test conditions.
Conventional test fuels and standard tests only partly represent reality. Therefore MANN+HUMMEL has considerably extended its standard test series. The test results of the RobustPlus pressure control valve are partly above the requirements by a factor of ten. And this is even with a doubling of the number of cycles, for example, with operational tests over the whole temperature range between minus 40° C and plus 150° C.
In this process the tightness, bursting pressure and control characteristics were tested. In addition to the standard inspection plan, the abrasion resistance, tendency to buckle and durability of the new design were examined. The new RobustPlus membrane passed all the evaluation tests with flying colors. The results of a chemical analysis of combustion residues included twelve acids. Only RobustPlus can withstand the chemicals.
Long service life
The first B prototypes have now been concluded and the new chemically resistant pressure control valve will shortly be launched on the market. In particular on the Chinese market the RobustPlus membrane promises a long lifetime and a long life for engines, also under critical operating conditions.