GMC Yukon

Car Technology

A hybrid heavy hauler

The new GMC Yukon weighs 2500 kilo grams less than the usual,which means it is no new comer.Not so surprisingly GMC Yukon uses the same technology as that of Toyota’s famous cars to reduce the energy consumption,by using new two-mode hybrid system.Two mode means,the car can be driven by all electric or together with the combustion engine.GMC Yukon has two electric motors which is quite new and no other hybrid cars have to boast off.The GMC Yukon’s batteries are charged by engine and by regenerative braking too.Each of the motor have 40 kW power.The reason there are two motors is that,a single motor that is capable of moving that much mass cannot be fitted into that frame.So to solve this issue the engineers of GMC joined hands with those at Daimler Chrysler and BMW as well,and used a pair of motors.This two motor system is not new,it have been used in the GM’s hybrid transit buses.Here also the the motors are not really motors only,they can function as a generator too.The technology in this baby is so complicated.

The frame of GMC Yukon,which is made up of aluminum,contains four fixed gears,a planetary gear set,a clutch,an electric motor,a secondary planetary gear system,again the second motor and then a final gear and clutch assembly.The planetary gear set is basically,a central gear,called as the “sun”,is powered by an electric motor or by engine the itself,which is surrounded by a ring gear,which is driven or drives another motor.With the planetary gear set,you are able to divide the power arbitrarily among the ring gear set,which means you can channel the right amount of power to the wheels and give the rest to charge the batteries of GMC Yukon,which is a 300 volt nickel-metal-hydride battery.

The two modes of GMC Yukon’s system refers to different mixes of engine and motor which drives the wheels.The first is called as input split mode.This one is for low speed and light load applications.The planetary gear system splits power to wheels and to one of the two motors,and this one is acting as a generator.This generator charges the battery and whose power is used to run the second motor,which is used to drive the wheels of GMC Yukon as well.

The second mode is called split or compound mode.This one is for heavy loads and high speeds.It provides electric power assist in the 3rd and 4th gears.Both electric motors can receive torque from the engine or power from the battery.Here the planetary gears not only splits the torque among wheels and motors,it also multiplies the the output torque of GMC Yukon.

The heart or the command center of GMC Yukon who is responsible for all these operations are microprocessors.70% of the total effort involved in designing and testing the GMC Yukon went towards the control logic,says Tim Crewe,the chief engineer.The microprocessors analyzes hundreds of inputs every 10 milli seconds.They include engine operations,load,battery conditions,temperature in various components.Depending on the speed and power requirement,motors are controlled individually,one might be aiding the engine or providing regenerative braking,while the other completely shut down,which gives maximum efficiency.Or both aid the engine to give instantaneous power.The planetary gears set helps to keep the system smooth while the system switches modes.

The GMC Yukon is expected to give a mileage of 10 liter per 100 km,a 25% increase in the fuel economy.You can compare these values with that of the standard GMC Yukon,it provides about 15 liter per 100 km (in the city),so the technology does pay off.

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