Wolfram Schmid, Director of Heavy Duty Engines in Truck Product Engineering at Daimler Trucks thinks so.... Euro VI, Japan 9 and EPA 10 are all tighter on the nasties, and at really, really low levels compared to where it all started. So further reduction won't be in quality of emissions, but quantity. So for big trucks that means aero and rolling resistance more than other things. For the heavy vehicle fleet, hybrid tech doesn't offer as much benefit. This is because long haul trucks spend much more time at speed on freeways than short haul trucks and passenger vehicles. So even if they were hybrids, they'd be running on petroleum fuels more of the time. Anyway, it's an interesting view, and the first time I'd seen it articulated like that.... Matt
I've nave not done any research on this but has there been discussion of treating long haul trucks like locomotives where petroleum based engine runs a generator that in turn provides the power to move the beast. This way the most efficient engine could be used to power the generator. Batteries could store excess output and energy retained from coast down operations to provide a kick when acceleration is needed.
When I was traveling in Australia, I would see these huge semi's (I think they called them "Land Trains"), supposedly their freight cost was much reduced. All I remember was they were pretty intimidating to have one coming at you. :eek6:
Nathan that's a series hybrid, like the Volt. And yes, you get to run the engine at it's most efficient point, and that helps for sure, but you have to have power storage and a generator/electric motor pair. I haven't seen the numbers about the efficiency gain you get when most of the driving is done at speed, where the base ICE engine can run at it's sweet spot anyway. For locomotives, one of the thing that drives the use of a series hybrid technology is that you can have the electric motors in the wheel trucks and the power generation on the suspended structure and you don't have to drive all that torque through the suspension. That Aussie truck/train is an example of how aero effects are a win. The parts at the back don't have to move much air so you just add rolling resistance of the wheels, mostly. I think Oregon or Washington allows tripple trailers, California doesn't. So for longer trucks to work, there has to be some unification of the road regulations. In CA, there are parts of the state that could work with triples, and lots where they would be a mess..... Matt Matt
Think those land trains work in Australia because of.the geography, long flat sections of road through no where with little traffic and not much stop and go... While there are places that they might be used here, most parts of the US are to populated and mountainous for their safe use... The exciting prospect of using the engine as merely a generator would be in the possible application of alternate fuels or a fuel cell. My understanding is that the Volt is already designed for a cell....
At one time I was in the Diesel engine business. There is some activity to allow longer trucks, similar to the triples in the North West. The debate on electric drive or mechanical drive for trains and large mine haul trucks has been ongoing. General Motors pioneered electric drive trains. Those trains generated DC current, and put an end to steam engines. Steam engines and electric motors generate maximum torque at 0 RPM. The diesel engine could be spinning at high speed and gets the train moving. The variable speed AC motors that are common today are the result of Siemens. There are a few hybrid drive trains and large mine trucks, but the vast majority do not have any regenerative capability. Electric drive is used to get the vehicle moving from a stop with a smaller power unit. The other issue is these vehicles do not have the speed range of cars, and so there isn’t a need for a transmission. Generally a mechanical drive has fewer losses than a electric drive. The primary advantage of electric is full torque at stall. Industrial engine life is rated by the duty cycle. This is the amount of power the engine is delivering over time. A different way of looking at it is the total quantity of fuel used in a time period. Cars use a very small portion of the available power. Even race cars use less than 50% power density on the typical road race track. Daytona is different. Line hall trucks and trains use a lot higher percentage of the available power. They get up to speed and stay there for long periods of time. Delivery trucks, like beverage trucks, or city busses, are great opportunities for hybrid. Parker Hannifin has a retrofit program with Coca-Cola to install a hydraulic motor / pump in the drive shaft. The motor or pump is attached to a hydraulic accumulator. More power for acceleration and recharging the accumulator under braking. The Europeans have had similar systems for a long time. Some Swiss busses have a giant spring similar to the main spring in a old clock or wrist watch. The spring is wound under braking or going downhill, and boost acceleration.