The polyphthalamide (PPA) with 35 wt. % glass fibres meets high requirements in terms of strength, dimensional stability – even at high temperatures, chemical and hydrolysis resistance as well as suitability for injection moulding. The manufacturing costs are considerably lower than those associated with the diecast-magnesium housings traditionally used for such units.
DuPont™ Zytel® HTN polyphthalamide (PPA) with 35 wt. % glass fibres meets the high requirements for the housing of a pneumatic switchover unit used in car air suspension systems, which is exposed to internal pressures of 16 bar. The unit was developed by Woco for Continental Automotive Systems. It is directly connected to the compressor unit and manages air supply to the suspension system. Electronic air suspension systems allow the bodywork to be raised during journeys on uneven ground, for example, to ensure greater chassis clearance.
This is mainly due to the fact that no further refinishing work is required, such as deburring, and that the complex-shaped parts can be produced in a single manufacturing stage.
The switchover unit, with the housing made of Zytel® HTN, contains coils, electro- and pneumatic valves as well as several check valves. It is connected directly to the compressor unit and manages the air supply to the suspension system. Depending on the vehicle make, it is installed either under the front bumper, in the vicinity of the exhaust or in the car’s interior, e.g. in the spare wheel cavity. Thus the housing is exposed to aggressive media such as cleaning and brake fluids, oils, lubricants and contaminants such as dust, sand, etc. during its entire lifetime. Working temperatures range from -40 °C to 80 °C. Short-term temperature peaks can reach 120 °C at a maximum operating pressure of 16 bars. In its new condition, the housing is required to withstand a burst pressure of 35 bars.
“We chose Zytel® HTN PPA 51G35 due to the positive experience we have had with the material to date,” says Peter Henninger, development engineer at Woco. “It meets all our requirements in terms of mechanical strength and is highly-suited to this application. Moreover, the material maintains its very high dimensional stability and accuracy even at very high temperatures. This helps ensure that an air-tight seal is created between the switchover unit and the compressor unit for its entire lifetime, which is in turn critical for the reliable operation of the air suspension system.”
The complex-shaped housing – measuring 133 mm long, 83 mm wide and 70 mm high – is produced using precision injection moulding. The high flowability of the Zytel® HTN grade used, and its very low tendency to warp, enable production within tolerances of +/- 0.05 mm. Moreover, because refinishing work such as deburring or machining is not required, in contrast to comparable housings made of diecast magnesium, the housing can be processed for assembly as soon as it leaves the tool – saving both time and cost.Background: Air suspension systems
An air suspension system consists of four air spring struts and integrated dampers, each with continuously adjustable characteristics and switchable, additional air volume. In addition there is a sensor system with travel and body acceleration sensors. The system is rounded off by the pressure supply unit with switchover unit and pressure reservoir, as well as a valve block with pressure sensors. The control unit uses signals from the travel sensors to calculate the current height of the chassis, which it then manages by inflating or deflating the air springs. In addition, it prevents the car from bouncing up-and-down when travelling on uneven roads – indeed the car position is so quiet and even, it is as though it is anchored in the sky (the so-called Skyhook-Principle).
The DuPont Engineering Polymers business manufactures and sells Crastin® PBT and Rynite® PET thermoplastic polyester resins, Delrin® acetal resins, Hytrel® thermoplastic polyester elastomers, DuPont™ ETPV engineering thermoplastic vulcanizates, Minlon® mineral-reinforced nylon resins, Thermx® PCT polycyclohexylene dimethylterephthalates, Tynex® nylon filaments, Vespel® parts and shapes, Zenite® liquid crystal polymers and Zytel® nylon resins and Zytel® HTN high-performance polyamides. These products serve global markets in the aerospace, appliance, automotive, consumer, electrical, electronic, healthcare, industrial, sporting goods and many other diversified industries.
DuPont is a science-based products and services company. Founded in 1802, DuPont puts science to work by creating sustainable solutions essential to a better, safer, healthier life for people everywhere. Operating in more than 70 countries, DuPont offers a wide range of innovative products and services for markets including agriculture and food; building and construction; communications; and transportation.
The DuPont Oval, DuPont™, The miracles of science™ and Zytel® HTN are registered trademarks or trademarks of E.I. du Pont de Nemours and Company or its affiliates.This press release is based on information provided by:
Horst Ulrich Reimer | Du Pont
Improvement of the operating range and increasing of the reliability of integrated circuits
09.11.2016 | Technologie Lizenz-Büro (TLB) der Baden-Württembergischen Hochschulen GmbH
New algorithm for optimized stability of planar-rod objects
11.08.2016 | Institute of Science and Technology Austria
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water
In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
06.12.2016 | Health and Medicine
06.12.2016 | Life Sciences
05.12.2016 | Power and Electrical Engineering