From clean Stage V diesel engines to hybridised drivetrain applications that are fit for series production.
In the extremely demanding conditions in the construction, mining and agriculture industries, modern commercial vehicles have to demonstrate maximum efficiency and performance. The leading manufacturers of industrial engines are responding to these requirements with a modular system that includes high-tech diesel engines as well as electric and hybrid drive concepts.
Electrification ensures maximum flexibility
If e-mobility determines off-highway applications, electric motors are responsible for driving and performing the main function of the commercial vehicles – from DC/DC voltage converters, power distribution units and gearboxes for hybrid and electric vehicles up to and including high-voltage fuses. Systems & Components exhibitors will be demonstrating how new technologies can be integrated into existing machine designs with increasing ease. To accomplish this, the classic hydraulic system is being replaced by an architecture with electromechanical linear drives, thus optimising power transmission. At the same time, the latest generation of electric drives aims to prove themselves with high output. One essential element of this is a battery-exchange concept in which energy storage units can be transported and used where necessary.
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Whether a fully electric drive concept makes the most sense from an economic point of view and offers sufficient customer benefits is largely dependent on the application and its resulting load profile. Great potential is foreseen for hybrid and fully electric drives, particularly for small- and medium-sized machines. Optimum possible applications are therefore initially found in the lower power categories, that is in all-terrain wheel loaders and excavators. The drives offer customary power while performing combined movements considerably faster. The drives currently installed in the drivetrain achieve a continuous electric output of about 60 kilowatts. This output can also be temporarily increased to more than 100 kilowatts for acceleration or boost phases.
The most recent innovations include wheel hubs with three-phase asynchronous motors that were developed specifically for use in agricultural and construction machines to make working under difficult conditions easier thanks to controlled traction support. Examples of this include electrically driven axle systems for trailers or electrically driven support wheels for attachments. Allocating the drive power to additional wheels offers a number of advantages. Backhoe loaders, for instance, are able to cope far better on difficult terrain. Higher-powered attachments can also be moved or tractors can be downsized, thus reducing both fuel consumption and soil compaction.
Hybrid drives from the modular system
Hybridisation of the drive train is increasingly shifting into focus as an alternative to pure diesel engines for medium-duty applications up to 200 kilowatts. Solutions consist of a combustion engine, an electric motor with matching power electronics and a battery pack. The majority of vendors rely on lithium-ion technology for the rechargeable batteries; depending on which size is installed, these provide sufficient capacity for up to eight hours of heavy work. Thanks to a gearbox with an integrated separating clutch, the diesel engine can be decoupled in parallel hybrid systems, allowing vehicles to operate purely electrically. The technology also enables combustion engine downsizing with enormous potential fuel saving: ideally, consumption can be reduced by up to 40 percent.
In serial hybrid systems, the diesel engine drives a generator rather than the wheels themselves. Power inverters convert the electricity produced by the generator and route it to electric motors on the front and rear axles, which in turn drive the wheels. Experience acquired in the passenger car sector can be transferred to off-highway applications in which range extender hybrid technology is implemented. All of the advantages of the electric drive can be exploited in these applications, while a diesel generator ensures the necessary range and operating time.
Alternative fuels of the future
The combustion engine remains the first choice, particularly in heavy-duty applications with high output and torque requirements, and is indispensable in construction and agricultural machines. In Hanover, exhibitors will be demonstrating extensive system expertise encompassing engine management, sensor systems and exhaust gas aftertreatment as well as fuel injection technology. However, engine manufacturers are not only extending their product ranges in terms of displacement but also in regards to the choice of fuel. Many of the models exhibited at Systems & Components follow a platform concept, enabling identically designed engines to be implemented with different combustion processes – including diesel engines with catalytic converter and particulate filter (Stage V ready) and spark-ignition engines with electronic ignition for petrol, liquefied petroleum gas (LPG) or natural gas.
Following significant efforts to reduce fuel consumption and implement intelligent exhaust gas aftertreatment solutions in recent years, the current focus is shifting increasingly towards alternative fuels. The latest generation of engines is successively being approved for the use of paraffinic diesel fuels or biodiesel blends. In the future, these are also likely to be joined by e-fuels on an industrial scale; based on regenerative electricity, these actually promise CO2-neutral operations.
