Continuing just-auto’s series of interviews with global tier one suppliers, Matthew Beecham talked with Anna Strehlau, Engineering Manager, New Business Development, BorgWarner Morse TEC about how the supplier’s variable cam timing technologies fit best to improve fuel economy and performance of downsized engines.
Currently downsizing is classified as the most productive strategy in engine manufacturing for reducing emissions and fuel consumption. What components play a vital role inside the engine in this case?
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In addition to direct injection and turbocharging, valve event timing is an essential factor in engine downsizing as the times at which inlet or outlet valves open or close can influence low-end torque and overall engine performance.
Valve event timing uses cam phaser technology. What key attributes do cam phasers have in regard to the savings capacity of downsized engines?
Variable cam timing using cam phasers allows the charge cycle losses to be reduced under partial load and the cylinder charging to be increased under full load. BorgWarner Morse TEC provides highly engineered variable cam timing (VCT) systems focused on minimising energy consumption to improve fuel economy and vehicle performance. With best-in-class simulation capabilities and state-of-the-art testing facilities, BorgWarner’s product portfolio includes various cam timing systems that offer a broad range of solutions designed for a variety of engine configurations.
In terms of the types of BorgWarner’s variable cam timing technologies, what solutions do you offer exactly and where is the difference between them when you think of operating modes and market positioning?
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By GlobalDataBorgWarner Morse TEC offers oil pressure actuated (OPA), torsional assisted (TA) and cam torque actuated (CTA) phaser technology to achieve reliable variable cam timing to best complement individual engine architectures. Auto manufacturers profit from these innovative solutions as the variable cam timing systems from BorgWarner contribute greatly to making engines considerably more efficient while reducing emissions and enhancing performance. In addition, BorgWarner’s advanced variable cam timing technologies provide a reliable solution to improve cold-start performance.
What was the reason for BorgWarner to bring multiple different phaser technologies to market?
Today we have a rising demand for in-line three and four-cylinder engines because this configuration supports the downsizing principle and its potential is most suitable for improving fuel economy and reducing emissions. Variable valve timing can enhance the performance of these smaller configurations by expanding calibration opportunities. In addition, larger displacement engines such as V6 and V8 benefit from the fuel savings of variable valve timing technology. Therefore BorgWarner is continually expanding its technologies for variable cam timing and enhancing its portfolio of cam phasers.
Can you describe whereby the differences within the BorgWarner cam phaser family could be identified? Which functional principle does each phaser follow?
The simplest and most conventional solution for variable cam timing is BorgWarner’s oil pressure actuated (OPA) phaser technology. This adjustment system uses a hydraulic actuator driven directly by engine oil pressure. By simply using the available engine oil supply, the camshaft can be phased relative to the crankshaft while the engine is running. Here the timing angle is set via the alternate filling of two oil chambers. Suitable for all engine types, this reliable entry-level and low cost solution reduces engine parasitic losses while improving vehicle performance. The more powerful torsional assist (TA) phaser technology uses the available camshaft torsion energy coupled with engine oil pressure, providing a flexible solution for all engine configurations, including boosted four-cylinder applications. The advantages of this technology are an incremental reduction in oil demand and faster response time in comparison with OPA technology.
What is your state-of-the-art cam phaser technology?
For maximum performance as well as high speed actuation independent of engine oil pressure, BorgWarner offers its cam torque actuated phaser technology. This solution takes advantage of the existing positive and negative cam torque energy generated during the opening and closing of the inlet and outlet valves. While OPA and even TA phasers must limit their range of travel based on swept volume requirements, the innovative CTA design can support a range of authority of 100 degrees crank or more. In addition to the considerably larger timing angle and faster response, other benefits of this technology include its ability to actuate over the entire speed and temperature range, such as during cold-starts or engine cranking.
Which VCT configuration best complements start-stop systems?
BorgWarner’s CTA phaser technology is best suited to the requirements of start-stop systems, in particular when cam angle adjustment is required at very low engine speeds or during cranking. Overall these technologies complement each other to provide better efficiency, lower fuel consumption and offer a considerable improvement of the ability to take advantage of advanced combustion strategies. In this way, CTA technology solves the target conflict between increased engine performance and improved efficiency.
Cars equipped with start-stop system have to make millions of re-starts in their life time cycle and often conditions inside the engine are not ideal for a fast and smart restart with regard to the positions of crankshaft and pistons. Which challenges had to be mastered?
To address this need, we are building upon our patented mid position lock technology, which was named a Pace Awards finalist in 2011. Conventional cam phasers have a predefined lock situated at the end-stop position. This lock position, especially in the case of an expanded range of authority cam phaser, may not be optimal for all the potential engine re-start conditions. BorgWarner’s mid position lock technology circumvents this disadvantage by providing a default lock position which can be freely defined in an intermediate position within this range of authority. Cam timing systems equipped with this function allow an extended maximum lift range which in turn permits the camshaft position required in each case to be calibrated more precisely. Patented hydraulics provide for the reliable repositioning of the system to mid position when necessary, such as during a cold-start, while relying on a more conventional end-stop lock pin position for a warm-start during start-stop operation.
How is the lock system reacting if the engine gets switched off regularly or something unexpected happens?
The mid position lock technology is equipped with a fail-safe function, so that if there is a sudden loss of power, or the engine is stalled, the mechanism is automatically returned to mid position and locked there. This avoids any problems which could occur when restarting the engine if the cam timer is in an unfavourable position. CTA and TA phasers with integrated mid position lock technology are also available with an integrated centre bolt and spool valve for smaller package size and easier installation.
Government regulations for reducing emissions become more and more stringent in several countries and regions. Does BorgWarner notice an increasing demand for VCT technology and other systems which help OEMs achieve the ambitious goals in fuel economy and less CO2 emissions?
Especially our VCT technologies are on high demand regardless of fuel type. The most recent addition to BorgWarner’s production portfolio is a cam phaser family for I4 engines. The technology is planned to launch with a major global automaker on diesel and gasoline applications in 2015. Both will be supported by production at a new facility in Eastern Europe. The new facility complements a number of existing global facilities producing VCT technology and strengthens BorgWarner’s ability to support global customers with local production. I4 engines have captured about 75 percent of the global engine market and are forecast to power over 17 million additional vehicles in the next six years.
The South America market for up-to-date supplied components is considerably growing, too. How is BorgWarner reacting on this, especially when you think of the new and stringent INOVAR-AUTO regime goals in Brazil?
With our new production facility and engineering centre in Itatiba City in Brazil, BorgWarner is ideally positioned to support car manufacturers in complying with this new regulations which aim to increase technological development to improve fuel economy, innovation, environmental protection and energy efficiency as well as the quality and safety of vehicles and auto parts produced in Brazil. Our new campus will produce several environmentally friendly technologies for passenger cars and commercial vehicles such as turbochargers, viscous fans and fan drives, engine timing systems and emissions technologies. It is located 80 km northwest of São Paulo and is twice as big as our former facility in Campinas, where we entered the Brazilian market in 1975.
In which way does BorgWarner support OEMs in complying with the new regulations in Brazil?
The remainder of this interview is available on just-auto’s QUBE research service
