www.gates.com/europe

Gates GmbH Eisenbahnweg 50 D-52068 Aachen Germany Tel: (49) 241 / 5108-0 Fax: (49) 241 / 5108-297 Website: www.gates.com/europe

Advanced Power Transmission

Engine power transmission has seen significant changes over the last decades. Car manufacturers’ requirements for drive systems are becoming more and more severe. Hence belt manufacturers need to develop new and improve existing products constantly. Gates anticipates and follows the demands of the car manufacturers and has developed advanced products, systems and modules to meet the stringent requirements.

A NEW MODULAR APPROACH TO THE TIMING AND ACCESSORY DRIVE SYSTEMS FOR PASSENGER CAR ENGINES

The automotive industry in general has developed towards the increasing use of modules. These are relatively complex sub-assemblies designed to simplify assembly operations in the vehicle manufacturing plant and generally delivered on a just-in-time or even just-in-sequence basis. Examples in current production include door modules, cockpit modules and front-end modules. Most progress has been made in the vehicle assembly area, and penetration of modular principles into the powertrain arena has been relatively limited.

Gates' new module, GEM10™, is aimed at the powertrain area. It is a unit which incorporates both the timing drive to the camshafts (and injection pump in the case of diesel engines) and the Front End Accessory Drive or FEAD. The driven machines such as the alternator and air-conditioning compressor are also included, as are the engine oil and water pumps if required. The whole unit is pre-assembled in such a manner that the belts are routed, camshaft and other "floating" pulleys are retained in position and the drive tensioners are primed, ready for release by the withdrawal of a pin. Every fastener and dust cover is captive so there is no requirement to feed the engine assembly line with any hardware alongside the module itself.

Simplified assembly process

Instead of the traditional 15 or more assembly stations employed to fit these components, the process is reduced to a minimum needing only 1 or 2 stations. All that is required is to locate the crank and cam(s) in the appropriate position, lift the module onto the mounting guide rails and slide it back to engage with the shaft ends, then run down the fasteners and remove the timing pulley locking device. Finally, release the timing and accessory belt tensioners and the dust covers, which are retained on Polypropylene hinges, so that they can then be snapped into place. The whole process is complete in less than 3 minutes.

Benefits

The concept has been proven in hardware using a conversion on an existing engine. Whilst conversions are possible, the idea will yield its best potential when incorporated into a new engine design at the concept stage. Gates is confident that this will allow packaging benefits, both along the crank axis and in front elevation, weight advantages and an NVH improvement over traditional designs. The much simplified assembly process allows dramatic floor space, investment and labour savings to be made in the assembly plant. Furthermore, something of the order of 95 components and 50 part numbers are reduced to a single module, a complexity reduction which permits further savings to be made. Additional benefits are also expected with respect to quality, because the assembly process for the module is much more ergonomically sound and more easily automated. Durability and reliability are also expected to benefit because the timing drive will be better dust-proofed and weatherproofed. It is also anticipated that, as a result of the packaging advantages, yet further complexity reductions – at a power unit level - should be attainable because fewer dress variations to meet vehicle package requirements will be necessary. This would enhance manufacturing flexibility and provide another lever to drive total operating costs down.

ALMOST COMPLETE SILENT VEHICLE START UP WITH EMD

Gates’ advances in higher capacity EPDM Micro-V^® multi-ribbed belts and automatic tensioner designs are driving Gates’ pioneering research and development in electro-mechanical drive systems (EMD). Major electrical system suppliers work closely together with Gates, relying on the company’s advanced knowledge of belt drive systems, to create belt driven starter/generator systems for the OE’s. The new EMD starter/generator systems use a belt drive to provide almost completely silent vehicle start-up via a combined starter-alternator. The system allows the engine to stop when the vehicle is stationary, for example at traffic lights, then restarts the engine almost instantaneously. This technology enables the practical use of engine stop/start strategies for reduced emissions and increased fuel efficiency. EMD enables brake energy regeneration and transient torque boost. The system is applicable with either 14 or 42 volt systems. The first integrated starter/generator, based on the Gates Electro Mechanical Drive system (EMD) is in production with PSA Peugeot Citroën.

In order for the Gates EMD system to meet the performance requirements of car manufacturers all over the world, advanced drive components had to be designed: a special high performance Micro-V^® belt, EMD1, tensioners and crankshaft damper. Thanks to a special belt composition using a high-performance rubber compound, advanced adhesion technology and enhanced cord material a special hi-torque Micro-V^® belt has been developed to transmit torques of up to 70Nm provided by Starter/Generator machines and this for up to a 1.000.000 starts. The result of this belt development project is a breakthrough in belt technology that allows the incorporation of an EMD system into an engine without modifying the current production drive pulleys or accessories, saving costs to convert a vehicle into a mild-hybrid. Gates also developed a variety of belt tensioners in order to meet all system requirements. For example, mechanical tensioner arrangements or a hydraulically damped tensioner allow the EMD system to control belt tension during both starting and generating modes. Furthermore Gates has developed a crankshaft damper that can carry the torque loads required through the inertia ring to start an engine. All newly designed components have run extensive tests to ensure their performance meets or exceeds the OEM’s demands.

ADVANCED TIMING BELTS

The timing belt itself has also changed a lot over the last few decades. The newest technologies enable the belt manufacturers to produce belts that last much longer than the traditional 90.000-120.000 km. Cooperation between car and belt manufacturers and their joint research and development activities continuously drive the timing belt towards the future.

The conditions in which the drive systems have to operate have become much more severe over recent years. The fluctuating torque the camshaft imposes on the timing drive has increased fivefold over the last 10 years, and this with temperatures under the bonnet that easily reach 150°C. Nevertheless even in these extreme conditions the timing belt sticks up for itself, thanks to continuous developments from the belt manufacturers.

The main developments of the timing belt are concentrated on the future demands of the car manufacturers with respect to space, temperature, dynamic stress and lifetime. The three main components of the belt, tensile cords, rubber compound and jacket, are constantly the object of further research. The rubber compound for example, was originally based on polychloroprene. With the conditions in the engine becoming more severe there was a demand for a better rubber compound so sulphur cured HNBR (Hydrogenated Nitrile Butadiene Rubber) was introduced. Now further improvements have been made and peroxide cured HNBR is becoming increasingly well established.

Gates maintains technical centres, strategically located to complement those of the car manufacturers. As a result, product, modules and system design programmes can be linked directly to the customers, throughout the world to accommodate simultaneous engineering.

Gates GmbH
Eisenbahnweg 50
D-52068 Aachen
Germany

Tel: (49) 241 / 5108-0
Fax: (49) 241 / 5108-297