trailer world issue Two 2008

Ausgabe Zwei 2008 19 Only pressure creates innovation. This is not a rule of physics, but a rule of life. The current pressure for action on the industry caused by rocketing energy prices is increasing the speed of innova- tion in hybrid technology. The best example is the hybrid Canter. Mitsubishi Fuso has already had its 7.5 tonne Canter truck on the market in Japan for two years. According to the group parent company Daimler, over 200 units have been sold so far. This is not many, although nevertheless still a be- ginning. A market success with- out the preﬁx “major trial”: Pri- vate users were still buying the vehicles for the purposes of in- ner-city distribution traﬃc. The Japanese had no other choice: in certain districts of Tokyo and other major cities, the ZERO- EMISSION rule applies. And this is only feasible with an electric drive. The extra price for the hybrid Canter, around €10,000 according to Daim- ler, would be largely subsidised by the state in Japan. Such “in- centives” were still lacking at the time with us, complain the Daimler sales strategists. And not completely without justiﬁ- cation – as demonstrated by the advance Euro-5 sales of heavy trucks: whoever switched quickly to the latest exhaust gas technol- ogy would be rewarded with reduced toll charges. The additional costs for the Euro-5 technology were completely recouped by these hauliers in less than two years. Despite drastically increasing diesel prices, the transport sector is still very cautious about alternative drives. Operators of commercial vehicles have nevertheless understood that a hybrid concept can only be used economically for its energy recovery, and therefore only in city traﬃc, with its frequent acceleration and braking procedures. The forecast consumption savings in diesel fuel amongst developing manufacturers are in the region of 30%, presupposing predominantly stop-and-go traﬃc. Everyone is also agreed that only one parallel hybrid can be success- ful in the scenarios of European distribution traﬃc. The PARALLEL HYBRID refers to the joint or alternating drive of a truck by an ELECTRIC MOTOR and/or a DIESEL ENGINE. The diesel engine and electric motor are in this case arranged for example so that ac- celeration is handled exclusively by the electric motor. The high- torque electric motor can how- ever also be switched in parallel with the diesel engine (“boost”), in order to handle acceleration, overtaking or gradients more quickly. Shorter inner-city deliv- ery routes should be able to be serviced with the hybrid truck exclusivelybyelectricmotor.This use with “full hybrid” status can- not however always be achieved – or only in a very limited radius of action of a few kilometres. A further characteristic of the parallel hybrid is its capability of RECUPERATION. This refers to the conversion of braking en- ergy into electrical energy, which in turn recharges the vehicle bat- teries. A requirement for this is that the electric motor acts as a generator in propulsion opera- tion. All hybrid concepts for trucks fulﬁl this requirement, so that in propulsion operation the electric motor can also be used as a genera- tor and almost as a retarder, which simultaneously spares the service brakes and signiﬁcantly reduces brake wear. How one can design such a drive train elegantly, i.e. in a continuous driveline, has been demonstrated by ZF as a system developer and supplier of complete assemblies. The ZF hybrid comes in three con- ﬁguration stages: stage one concerns only the electric motor (54 kW) with its actuators and clutch. Mercedes for example installs this Technology Issue Two 2008 19 Photo:Wilms

trailer world issue Two 2008

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