Free Newsletter
Register for our Free Newsletters
Newsletter
Zones
Advanced Composites
LeftNav
Aerospace
LeftNav
Amorphous Metal Structures
LeftNav
Analysis and Simulation
LeftNav
Asbestos and Substitutes
LeftNav
Associations, Research Organisations and Universities
LeftNav
Automation Equipment
LeftNav
Automotive
LeftNav
Biomaterials
LeftNav
Building Materials
LeftNav
Bulk Handling and Storage
LeftNav
CFCs and Substitutes
LeftNav
Company
LeftNav
Components
LeftNav
Consultancy
LeftNav
View All
Other Carouselweb publications
Carousel Web
Defense File
New Materials
Pro Health Zone
Pro Manufacturing Zone
Pro Security Zone
Web Lec
Pro Engineering Zone
 
 
 
News

Cost and space-saving pneumatic valve block of Zytel HTN

Du Pont Engineering Polymers : 23 May, 2002  (New Product)
Electro-pneumatic converters turn electrical control signals into pneumatically operated movements. Typical automotive applications are for adjustment of guide vanes in turbochargers, exhaust gas recirculation systems or the cut-off valve of Diesel motors. Usually these functions are carried out by single valves which are distributed around the motor compartment, and then must be individually connected. Woco's modular valve block, installed in the Diesel-powered version of the new VW Polo series, is a more cost-effective method of meeting the same needs.
Woco, a German systems supplier to the automotive industry, has developed a modular valve block for use in Diesel motors of cars and goods vehicles which can replace several individual valves, thereby saving costs and under-the-bonnet space. The block and the functional parts in it are made of DuPont's semi-aromatic Zytel HTN high performance polyamide, which combines dimensional stability with high thermal and chemical resistance.

Electro-pneumatic converters turn electrical control signals into pneumatically operated movements. Typical automotive applications are for adjustment of guide vanes in turbochargers, exhaust gas recirculation systems or the cut-off valve of Diesel motors. Usually these functions are carried out by single valves which are distributed around the motor compartment, and then must be individually connected. Woco's modular valve block, installed in the Diesel-powered version of the new VW Polo series, is a more cost-effective method of meeting the same needs.

Depending on the composition of the module, the new valve block integrates many electro-pneumatic functions within a single housing. This unified design and modular construction reduce manufacturing, assembly and logistics costs, eliminate the risk of incorrect connections, and save precious space in the engine compartment. In summary, it opens substantial cost-saving possibilities for the automotive industry.

In the first manufacturing step, Woco overmoulds a perforated metal screen which serves in the finished part as the conductor between the various electrical contacts. In a second step, this moulded part is again overmoulded with the resin that forms the housing.

Uwe Reichert, development manager in Woco's modular technology department, comments: 'Together with DuPont, we found two grades of this semi-aromatic Zytel HTN nylon which fully met our complex requirements. Both are from the 53 series; they combine high thermal resistance with good dimensional stability and dielectric properties. This ensures reliable current flow without short circuits or interruptions. These polymers resist all the liquids, chemicals and salts that can find their way into a motor compartment, and they can take under-the-bonnet temperatures which can reach 140 °C. They also maintain their high stiffness, so that leaks are highly unlikely.'

For the ultrasonically welded housing Woco uses a hydrolysis-stabilised type of Zytel HTN which is 50 % glass-fibre-reinforced and has a good balance of toughness, high strength and impact resistance. Its good surface characteristics make it an ideal choice for the housing, which must retain its sealing ability for many years, in spite of chemical attack, thermal fluctuations and mechanical stress. Says Reichert: 'We saved a lot of time developing the housing, because DuPont's finite-element calculations helped us to position and shape the mounting points in such a way that the housing stays in place firmly on the engine compartment rear bulkhead even under demanding dynamic and thermal stresses.'

For the many working parts in the valve block, including the coil cores, DuPont recommended another heat-stabilised grade of Zytel HTN which is glass- and mineral-reinforced. The mineral filling further improves the resin's warpage characteristics. As a result, this grade is suitable for parts whose dimensions must stay within very close tolerances after manufacture as well as in extended use.

Zytel HTN is a family of semi-aromatic polyamides with a combination of properties which make them ideal materials for demanding under-the-bonnet applications. Their properties include low moisture absorption, good dimensional stability at high temperatures, creep resistance, chemical resistance, and low warpage. The HTN 53 types which Woco uses were developed for highly stressed structural parts, where high stiffness and impact resistance are essential. Typical automotive applications for Zytel HTN resins include resonators, thermostat housings, cooling system components, fuel rails, connectors and ignition coils.

The Woco Group, based at Bad Soden-Salmünster, near Stuttgart, Germany, is a family-owned and family-managed global enterprise. In 2000 it had 4 100 employees and a turnover of about EUR 540 million. Woco's automotive technology department invests heavily in research and development, and offers comprehensive solutions in the realm of air-borne and structure-borne noise, including motor acoustics and anti-vibration systems, driving comfort and vehicle movement dynamics. In 2000 Woco established a joint venture with Michelin, called Woco Michelin AVS. Under the brands Woco, Elaplast and Effbe, the group offers qualitatively superior products and integrated solutions for many applications in the automotive industry, as well as in domestic appliances and flexible fluid transportation systems.
23 May 2002

World's first SMD potentiometer relies on high-performance parts of Zenite LCP and Zytel HTN

Piher-Nacesa, the Tudela (Spain) based operation of the electronic sensor division of British engineering group Meggitt PLC, has selected glass reinforced DuPont Zenite LCP liquid crystal polymer for the protective housing of its new N15 carbon position sensor/potentiometer and Zytel HTN high performance polyamide for the sensor's rotor.

Glass reinforced Zenite LCP was selected for the N15's housing due to the liquid crystal polymer's ability to resist the extremely high temperatures encountered in the SMD soldering process. Piher-Nacesa's Technical Director, said: 'Very few plastic materials can withstand such high temperatures. However, both our own in-house testing and also extensive customer trials have shown that Zenite LCP performs excellently in this application, even when the printed circuit board (PCB) must pass through the SMD soldering process twice in order to solder multiple components. This is especially impressive because the procedure requires the PCD to stay in the furnace for 10 minutes' duration for each soldering, at temperatures peaking as high as 260°C.'

DuPont's liquid crystal polymer was also selected because of its excellent mould flow characteristics, suited to the very small (15 mm × 15 mm) dimensions of the sensor, which has walls as thin as 0.5 mm. The outstanding mechanical strength and dimensional stability of glass reinforced Zenite LCP means that is it able to withstand the manufacturer's specification of 100,000 cycles with ease. Importantly, the engineering polymer displays very good flame retardant qualities, enabling parts that incorporate it to fulfil UL 94 and VO electrical specifications.

Piher-Nacesa selected a glass reinforced, flame retardant grade of another DuPont Engineering Polymer, Zytel HTN semi-aromatic high performance polyamide, for the N15's rotor because of the material's high temperature resistance, its excellent mechanical strength and low friction characteristics, and its very good productivity during processing because it also fulfils UL94-VO specifications.

The N15 can be incorporated by Piher-Nacesa customers into a range of highly-tailored printed circuit board (PCB) applications because it has a far greater degree of built-in flexibility than previous potentiometers. For example, it is the first carbon position sensor in the world that can be soldered onto a PCB using either surface mounted device (SMD) or through whole mount technology. Other features of the N15 that enhance its flexibility-in-use include endless rotation (360 degrees), extra-wide electrical angle (340 degree plus/minus 10 degrees) and an extended mechanical life of 100,000 cycles.

Other attractive features of the N15 include its working temperature range (minus 40 degrees to plus 120°C), its low profile (4.4 mm) and its low linearity at plus or minus 3 percent (standard). In addition, the new potentiometer can be re-flow soldered and shafts can be inserted from both sides. It is also compatible with a polarised 'T' rotor (European Home Appliance standard).

This flexible feature set means that the new potentiometer can be used in a wide range of position/rotary sensor and multi-purpose control applications in automotive, heating, ventilation and air conditioning (HVAC) applications. In the appliance industry, uses include temperature control, timers and function/programme selectors, to name just a few.

Piher-Nacesa's new N15 will become commercially available in January 2002. During 2001, it underwent extensive, highly successful customer trials at Bosch (power tool application), Honeywell (temperature control and heating system applications) and TRW (airbag switch application).

The Piher Group produces over 1.4 million potentiometers each day at its Nacesa factory and headquarters in Tudela, Spain. For the past ten years, Piher-Nacesa has used a wide range of other DuPont Engineering Polymers in its standard potentiometer range, including glass-reinforced, flame-retardant grades of Zytel nylon and Zytel HTN high performance polyamide, Crastin pbt thermoplastic polyester resin and Delrin acetal resin for housings and rotors and Zytel and Delrin for shafts.
Bookmark and Share
 
Home I Editor's Blog I News by Zone I News by Date I News by Category I Special Reports I Directory I Events I Advertise I Submit Your News I About Us I Guides
 
   Â© 2012 NewMaterials.com
Netgains Logo