The overrunning alternator pulley - an
unsung hero of the internal combustion engine?

In modern internal combustion engines, the overrunning alternator pulley (OAP) is an important component that often gets unfairly overlooked, particularly when you consider the positive effects it has on improving the energy efficiency of an engine.

The OAP is the functional interior of the belt pulley mounted on the alternator. The function of the OAP is to decouple the alternator from the rotational irregularities of an internal combustion engine. The task the OAP performs is therefore a critical one, particularly as the rotational irregularities that occur in the latest internal combustion engines - including turbocharged versions - are significantly higher than those indicated to the vehicle's driver by the tachometer needle.

In a vehicle's accessory drive, the alternator is the component with the greatest mass moment of inertia and the highest speed. This means that the acceleration and deceleration forces acting on the alternator resulting from the rotational irregularities have the greatest effect on the belt transferring these forces. The OAP therefore ensures that, at many operating points, only the accelerating proportion of the crankshaft forces that are transferred to the belt drive are used to drive the alternator. The advantages of the OAP with a one-way clutch are clear. The reduction in the force level in the belt drive extends the life (typically by a factor of 10) of individual components, while ensuring an increase in the generator speed and a reduction in noise. In addition to smoother engine running, the OAP also contributes towards the reduction of fuel consumption and therefore CO₂ emissions.

For example, in Schaeffler's CO₂ncept-10% concept vehicle, the OAP contributed a reduction of almost one per cent in fuel consumption. In urban traffic conditions - where a large proportion of time is spent idling and accelerating - the belt drive with the OAP is subjected to significantly lower loads than a belt drive without an overrunning pulley. Use of the OAP also enables the more cost effective design of other components in the overall belt drive system.

Volker Ploetz, Senior Manager Transmission Components at Schaeffler Group Automotive comments: "The overrunning alternator pulley works in a similar way to the freewheeling of a bicycle pedal, whereby only the acceleration proportion of the crankshaft's rotational irregularities is used to drive the alternator. The advantages from this include more effective damping of belt oscillations, which means you no longer need idler pulleys or damping pulleys. You also get a reduction of tensioning forces and lengths, as well as improved noise behaviour, reduced belt width and increased system life. The use of alternators with high mass inertia is also possible. In terms of assembly, the overrunning alternator pulley is easy to fit, as no separate fasteners are required."

This important contribution towards improving energy efficiency also explains why the OAP has been so successful in both diesel and petrol engines. The component - which has been established for around 15 years now - was regarded early on as a key component for eliminating the rotational irregularities from the belt drive of the new generation of high torque, direct-injection diesel engines. The OAP is now also included in the extensive list of measures for optimising the fuel consumption of internal combustion engines.

A comprehensive modular OAP system has been developed that offers many different custom designs for diesel and petrol engines, passenger cars, commercial vehicles and motorcycles. These include an OAP manufactured partly to aircraft specifications, which is used in the Schaeffler Audi A4 DTM.

The Schaeffler Group currently manufactures more than 400 different types of belt pulley with OAP. In fact, during the last 15 years, around 140 million of these unsung heroes have rolled off the production lines at Schaeffler.

For further information on the Schaeffler Group, e-mail: info.uk@schaeffler .com or view website: www.schaeffler.co.uk   Refer to page 391

Innovative thermal management module
reduces CO2 emissions by up to 4 per cent

The Schaeffler Group has developed a new temperature control system for automotive engine and transmissions. The system plays a key role in reducing CO2 emissions by up to 4 per cent for both internal combustion engines and hybrid electric components and batteries. The system is also ideal for use on engines with start-stop functionality.

Launched at this year's IAA Frankfurt Motor Show, Schaeffler's new Thermal Management Module is an innovative temperature control unit for the entire vehicle drive train. The module combines numerous functions into a single compact, integrated unit housed in a high-strength plastic enclosure.

Up to now, the temperature of almost all internal combustion engine-driven vehicles has been controlled by a thermostat mounted on the engine block. The engine is typically cooled by circulating water from a pump. The water pump operates continuously regardless of engine load. Even on engine start up when the engine is cold, the pump continues to operate - which is inefficient.

Schaeffler's Thermal Management Module precisely maintains the temperature of all drive train components according to requirements by electronically controlling cooling water distribution. This enables the engine to operate at the optimum temperature in response to changing engine load and driving conditions. For example, the cold running phase can be significantly reduced by switching off the water pump at engine start up. Individual components can also be run at higher temperatures than is possible in a thermostat-controlled engine. Engine temperature can be reduced under full load and the tendency for 'knocking' or having to enrich the fuel mixture under full load is also reduced using the Thermal Management Module.

By using a rotary slide valve, the Thermal Management Module is able to quickly reach the optimum temperature range for the engine and transmission. This has a positive effect on both the energy efficiency and life expectancy of components in the drive train. Turbocharger temperature can also be individually controlled by the module, ensuring after cooling of the thermally stressed, exhaust gas turbine.

The sensor-controlled Thermal Management Module enables the speed of the electronic water pump to be increased or decreased depending on the driving conditions. At full speed, the temperature of the engine can be decreased by the control module so that the fuel mixture doesn't need enriching, which in turn reduces fuel consumption. Driving at part-load means the temperature of the engine can be increased by the control module, enabling the optimum fuel mixture to be achieved.

The new module opens up a raft of opportunities for vehicle designers to improve the energy efficiency of both engines and heating & cooling systems for transmission and turbocharger units. For example, the module can be used to precisely control the temperature of alternators, hybrid modules and batteries, efficiently cooling or heating these systems according to individual engine requirements.

"The performance of the thermal management module makes this component particularly suitable for use in engines for start-stop operation," commented Prof. Peter Pleus, President of Schaeffler Group Automotive.

Like all Schaeffler-manufactured engine components and bearings, the individual components of the Thermal Management Module are friction-optimised for increased energy efficiency. Due to its low power consumption, the module can be fitted directly to the engine control unit without having to introduce additional power stages.

The Thermal Management Module releases the shackles from vehicle developers, who were previously constrained to fitting the temperature control unit or thermostat close to the engine block. Standard, interchangeable hoses ensure that assembly times for the module are minimised, as well as ensuring high sealing integrity.

For further information on the Schaeffler Group, e-mail: info.uk@schaeffler .com or view website: www.schaeffler.co.uk  Refer to page 388

Eco-PEN 450 extends the capability of volumetric dispensing

Intertronics' introduction of the preeflow® eco-PEN 450 from ViscoTec not only offers a greater capacity for high accuracy and highly repeatable volumetric dispensing - it also addresses the needs of a wide range of low to medium viscosity applications. These include oils and fats, colour mixes, silicones, sealing compounds, adhesives and even abrasive media, which can be easily handled by the innovative precision rotor-stator mechanism referred to as an "endless piston" by manufacturers ViscoTec.

The eco-PEN 450 deals easily with dots and beads as small as 0.004 ml at up to 6 ml per minute, featuring viscosity autonomous application at pressures from 16 to 20 bar via Luer lock nozzles or needles. Easy fitment to robotic systems is facilitated by preeflow® EC200 controllers which are available in bench top or panel-mount format. The units are microprocessor controlled and simple to operate, without submenu, and with graphic support. External signals can be connected via I/O ports to a PLC for control in automated lines. A wide variety of dosing programs with part-management are storable. The supply pressure (using pressure sensor kit) is monitored and can be displayed digitally in bar or psi. Error messages for filling level and motor current may also be monitored via an RS232 interface. Alternatively, for robotic and automated installations the preeflow® "plug-n-dose" Speed Control readily enables time/pressure control by external computer system.

The eco-PEN 450 is applicable to self-levelling low viscosity media and to non-self-levelling fluids with pressure feed.

For further information, view website: www.intertronics.co.uk or visit their blog at: www.adhere.uk.com

Sika's car factory solution

On a busy car production line random static charges can wreak havoc with sensitive electrical components affecting their reliability and causing equipment failure. This has created the challenge for car manufacturers as to how to minimise electro-static build up and discharge most often caused by floor coverings on a busy production line. 

Faced with this problem, MINI Plant Oxford turned to global manufacturer of construction products, Sika, for an anti-static flooring solution.

Plant Oxford needed a conductive floor system in its assembly hall so called upon the assistance of Sika who provided its Sikafloor® 262 AS Thixo, a 2-part electrostatically conductive textured epoxy coating.  With good chemical and mechanical resistance, this slip resistant flooring system is designed to deliver the ultimate in static control and has an excellent reputation in industries where there is sensitive electronic equipment. 

Sikafloor® 262 AS Thixo is a decorative and protective anti-static coating which is available in an unlimited choice of colour shades.  The unique high build system comprises a Sikafloor® 161 primer, Sikafloor® Earthing Kit, Sikafloor® 220 W conductive coat and Sikafloor® 262 AS Thixo wearing course.  It is suitable as a wearing course in industries such as automotive, electronic and pharmaceutical manufacturing.

Specialist flooring contractor Zircon applied 13,500 m² of Sikafloor® 262AS Thixo in a chosen colour of black. In order to provide minimum disruption to the manufacturing process on the assembly lines, this unique textured coating was installed in four separate phases. After first shot blasting the floor to remove any dust or loose material, Zircon applied Sikafloor® 161 primer by roller and brush. This was followed by the installation of the Sikafloor® Earthing Kit, a conductor system which comprises copper tapes and earthing points and then the roller and brush application of the Sikafloor® 220W Conductive primer. The final stage is the Sikafloor® 262AS Thixo which was applied using squeegee and then back rolled with an open cell roller to leave a textured finish.

The assembly hall at Plant Oxford now benefits from a thermostatically conductive flooring system which will ensure that the manufacturing facility is always on track to meet its target.

Sika offers a comprehensive range of flooring and coating products, designed for a variety of different applications and building or structure types. These solutions are backed up by a highly experienced technical team, who offer expert specification advice and support.

For further information on Sika's range of products, view website: www.sikaconstruction.co.uk