Technical Tips #19
|| Notes And Updates: 36-42 Volt power systems have been slow in coming to market. Interestingly the GM Partial Hybrid or E-Assist use 36 volt power systems.
New Power Systems are on the way:
An article in the February 20,1999 Toronto Star, titled "Electrics May Soon Take Over Mechanical Componentry" truly surprised me and as a result of that article I think we have not seen the end of gas powered motorhomes. The following is a paraphrase of this article by author, Mark Toljagic, used with his permission.
Mark quotes a development engineer who noted that cars are heated by the waste heat of relatively inefficient gasoline engines and that in colder climates these engines are not able to keep up with the heat requirements and often form ice in their crankcases. Automotive engineers are about to overhaul the modern engine all in the interest of higher efficiency, lower emissions and lighter weight. As good as modern four-cycle internal combustion engine is, it has not changed that much since the first one sputtered to life in 1876. Strip away the fancy cowlings and valve covers, it's a pretty crude looking machine driven by belts, chains and cogs. This 19th-century holdover is about to get a makeover.
Beginning in 2002 the auto industry will shift from 12-volt electrical systems to a 42-volt standard that promises to cut vehicle weight, boost efficiency and open the door to some exciting advanced technologies, such as electric powered steering, brakes and even valves. The 12-volt standard, introduced in the 1960's has become increasingly taxed - by the laws of physics not the politicians. No one back then imagined seats would not only adjust eight ways, but also be heated and ventilated electrically. Never mind the cell phones, global positioning systems and video entertainment centers consumers increasingly desire on board. By tripling the voltage (42-volts at the alternator, 36-volts at the battery) the current is actually cut by two thirds, allowing designers to use smaller gauge wire and shrink components.
Naturally a larger alternator and battery will be needed, a challenge that has been met by Delphi and Bosch, which have introduced liquid-cooled alternators that plumb into the cooling systems. The 42v systems will require two batteries, a robust one for engine starting and a smaller one dedicated to feeding the computer systems. Not only will there be lots of powers for all the toys, but - and this is the neat part - mechanical systems will be replaced with smart electrical components which take their cue from the all-seeing, all-knowing onboard computers. Instead of a belt-driven water pump that mindlessly circulates coolant at the same rate whether its -20C or +40C, an electric water pump will activate when the cylinder head heats up and not before, allowing the engine to reach operating temperature more quickly. Or, conversely, save your engine from a China Syndrome meltdown. Coming off a high-speed interstate and parking at a coffee shop can warp your engine. With an electric pump, the computer can keep the coolant circulating for 10 minutes after you have turned off the ignition, working the fan to dump the excess heat. Abundant electrical power will make other innovations possible:
- Electric steering, instead of power steering pump steering, that constantly draws power from the engine.
- Brake-by-wire, whereby self-contained units at each wheel are tied together by electronics in place of hydraulics.
- An electric air conditioning compressor that's more efficient, lighter and easier to package.
- An electrically heated catalytic converter to reduce emissions and improve fuel consumption during warm-ups. (BMW has already brought this to market)
The 42-volt system will free the engine of the drudgery of driving a serpentine belt loaded with pumps and compressors and have it turning only one: the alternator which in turn powers the newly added electrical motors more efficiently. A typical small engine will gain 10 to 20 horsepower.
There's more. Imagine a motor without a camshaft and the requisite timing chain or belt. Instead electro-magnetic valves control the intake and exhaust flow at each cylinder, electrically powered and controlled by a computer, instead of inelegant mechanical cam lobes and springs. You would not need a complex variable-valve camshaft. Just change the computer software to fit the mode of driving you require. The system could be programmed to close all the valves during braking so that engine compression helps scrub off speed. Or shut down two or more cylinders while cruising to reduce fuel use. The mind boggles. In essence the automobile engine returns to the primary function of propelling the vehicle, instead of running a glut of mechanical devices like a farm tractor with its power take-offs. Return to the lack of waste heat, the alternator would become a source of additional heat, especially in highly efficient diesel powered cars, said to have trouble warming the passenger compartment. An electronic thermostat, tied to the computer, can also help get the engine up to operating temperature quicker. Instead of a simple spring reacting to the temperature of the coolant, a digital thermostat can constantly adjust coolant flow to keep the head and oil temperature in the optimum range for cleaner burning and fuel efficiency. All of these interactive systems will require an onboard supercomputer that would make the one on Apollo 11look like a postage meter. It's a brave new world to be sure, but are these systems too complex to be manageable and more importantly, affordable? People used to think electronic fuel injection was too complicated to be practical in an everyday car. Today, carburetors are used for doorstops at corner service stations. Might camshafts be joining them?
With this background I began to dream a little about the future of motorhomes using this new power system. In Technical Tip #20, I will review my thoughts on what we might expect. And I welcome your thoughts on this as well.