TheMe: TurBO CharGinG Advancements Improve Engine Performance, Durability & Reliability >> TheMe Turbochargers come with several components. A Compressor Housing unit collects compressed air and directs it to the engine. The Turbine Housing collects exhaust gases from the engine which is then directed to the turbine wheel. The Housing and Rotating Assembly supports the rotating group. A Compressor Wheel pumps air into the engine intake, and the Turbine Wheel Assembly converts exhaust energy into shaft power to drive the compressor. A backplate supports the compressor housing and a bearing system supports the rotating group. Oil inlets and outlets are provided. Like most other parts and components in the transportation industry, turbochargers have improved over the years. In earlier days straight shaft models did compress air and increase flow to the engine, but there was a hesitation period between throttle activation and engine acceleration, a socalled turbo lag resulting from the time needed for the exhaust and turbocharger to generate the required boost. Inertia, friction and compressor load are the principal reasons for the hesitation, but can be reduced in several ways, including changing the ratio of the turbine, increasing compressor discharge, reducing friction and incorporating an anti-lag system. Manufacturers have since improved upon the turbo’s shortcomings with the introduction of the 4 <strong>January</strong> <strong>2013</strong> Variable Geometry Turbo for the precise amount of (VGT). These VGTs allow air delivered to the engine for the effective aspect at variable speeds. Cum- ratio of the turbo to be mins cites the following changed according to vari- benefits of the VGT Turboable conditions. Because charger: excellent transi- the turbo’s aspect ratio ent response, improved can be optimized at higher fuel economy, increased and lower speeds, only useful engine operating minimal lag is produced. speed range, proven dur- Efforts at reducing lag inable design, reduced encluded fitting turbos with a gine swept volume and wastegate, a valve that di- package size for a given verted exhaust gases away rating, and control of Ex- from the turbine wheel. haust Gas Recirculation. This helps to regulate Development of electric- maximum boost pressure ally assisted turbochargers in turbocharger systems. at Cummins is underway. A principal supplier of More variable geometry turbochargers for large Compressor housing engines on both on and offhigh Compressor Wheel wayapplications is Cummins. The Cummins VGT turbocharger is used with an EGR control valve to gauge the cooled exhaust gas into the intake system which enhances performance and fuel economy. The product’s sliding nozzle, when fully closed, creates increased backpressure in the exhaust manifold to force some of the exhaust gas through the EGR valve when it opens, thereby creating maximum exhaust manifold pressure where shaft speed and boost pressure are at their highest. When the nozzle ring is fully open, shaft speed and boost are at their lowest. The sliding nozzle allows information is available at www.cummins. com. Another of the world’s primary suppliers of turbos and powertrain solutions is BorgWarner. The company’s product portfolio includes conventional turbochargers with and without waste gates, turbochargers with variable turbine technology and regulated multi stage turbocharging systems (R2S). Filled compressor wheels and advancements in turbine technology pave the way for optimal performance, durability and reliability. The company’s new B series, which accompanies the previous generation K and S series, offers a range of sizes and models of low to mid range commercial engines as well Back Plate Turbine housing Variable Geometry Turbo (VGT) as engines employed in the construction, agricultural, industrial and marine sectors. BorgWarner’s variable turbine geometry in its BV range applies to diesel engines with displacements from 4 to 16 litres, or regulated Multi-stage Turbocharger (r2s) 244 to 976 cubic inches. Computational Fluid Dynamics incorporated into vane design and specially developed turbine wheels account for the BV turbochargers’ high efficiency and reliability. Notes BorgWarner, “Our BV turbochargers can be combined with pneumatic actuators or with electrical actuators developed specifically for this application. This in-house development offers massive advantages for the entire system. For applications with severe thermal loads, we also offer water-cooled bearing castings as an option.” As for t h e Trubine Wheel manufacturer’s R2S turbocharging technology, a small high pressure turbo combined with a large low pressure one contribute to high power capabilities and, by extension engine downsizing which reduces fuel costs. Nitrous Oxide emissions, too, are reduced through high gas recirculation rates made possible by the R2S technology. BorgWarner is now selling replacement turbochargers for the Mack E6 and E7 engines which are available through select suppliers. Warranties extend to 100,000 miles or one year. Refer to www. borgwarner.com for a full listing of the company’s product line. Another giant in the business is Honeywell Turbo Technologies which has an annual production rate of nine million units. Honeywell’s VNT DutyDrive turbocharger boasts increased fuel efficiency and power density. Variable sizes are suited to engines ranging from 2.5 to 15 litres, accommodating small delivery trucks up through onhighway applications and off-highway equipment. Key benefits include more engine power and torque, and a reduction in engine backpressure and fuel economy. This technology allows boost to the engine during braking which helps reduce brake wear, lower operating costs and improve vehicle productivity. More information on this, as well as Honeywell’s TwoStage Serial Turbochargers, is available on the com- honeywell’s VnT DutyDrive Turbocharger pany website, www.turbo. honeywell.com. Though turbochargers have become a standard fixture in heavy duty diesel engines they have, until recently, been installed in just 10 percent of passenger vehicles in North America. Europe far surpasses North America; about 50 percent of diesel engines in passenger cars have turbochargers and 27 percent of gasoline engines are boosted by turbochargers. The quest for environmentally friendly technology on this continent is expected to account for a doubling of turbochargers in North American passenger cars over the next four years. V
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