Toyota's Direct Injection Four-Stroke Superior version (D-S4) engine combines direct injection (which injects fuel into the combustion chamber) with port injection (which injects fuel into the intake ports). It controls the two types of injectors in accordance with driving conditions. Under heavy load, direct injection is employed. Under medium or high load, both types are used. In the drawing on the left, the engine uses both types of injectors (port injection is marked as "1" at the top). On the right, the engine uses direct injection only. (Source: Toyota)
I think the approach automakers are using is definitely supported by the need; i.e. looking at each component and improving that component's efficiency while evaluating what contribution can be made to reaching the CAFÉ standard. I don't really see how the standard can be achieved without significant improvement in technology and/or going to hybrid vehicles. With that being the case, the days of the shade tree mechanic are pretty much over. Growing up as a kid, my first lessons as a budding engineer came from working on cars. I suppose that will still be the case, but we could actually fix them back then. I'm not too sure a kid will be able to accomplish the same result with the new technology. In a way, this is sad evitable but sad.
The higher voltage systems for trucks and the 24 volt DC systems for military vehicles are for special uses. Military vehicles often had radio transmitterts and receivers, and the radio equipment in the tube type era could not run reliably on a 6 volt system. The 24 volt systems were for performance as much as anything else. In the trucks, the larger engines, especially the diesels, take a lot of power to crank. Also, trucks have a lot more lights than cars do.
There certainly was a push for the preheated catalytic converters about a year before the 42 volt systems were announced, so I see some cause and effect there. WE are all very fortunate that the preheated catalyst idea never took hold, since it would have been a functional disaster of embarrasing proportions. Just think about drawing 1500 to 2000 watts from your car battery for two minutes before you were allowed to crank the engine. With a new battery and a good electrical charging system it might work most of the time, but just try it on a cold winter night with a year old battery.
Fortunately rational thinking prevailed, and the beast was repelled.
Of course, there did turn out to be quite a few other challenges to making a 36 volt system work on common passenger vehicles. There were problems with light bulbs, switches, solenoids, and relays and some other components.
The consumers have always wanted better mileage, but they don't have enough influence on manufacturers because the profit margins are much thinner on inexpensive cars. The makers sell fewer luxury cars, but the luxury cars set the standards because their profit margins are better than 5 good mileage cars.
So market pressures never work. The car makers have failed to adapt to better mileage cars 3 times now, and each time the tax payers had to bail out the car makers. That neither works nor is fair. So regulation to make them produce better mileage is the only alternative. If we let the car makers keep failing, the whole country will fail.
Car makers are not making what people want, but what is most profitable in the short term, for them. And they ignore the long term, cyclic gas shortages, and the fact the short lived, delicate stuff they pack new cars with, are going to anger buyer is about 5 year when it all starts to break.
When I was working for Analogy (now owned by Synopsys), we were helping Volvo design for 48 volt systems for trucks.
It was not to heat converters or power busses.
It was to cut the weight of conductive wires by 2/3s, and to allow for a clean 12 volt DC source for microporcessors. The higher the voltage. the less amperage you need for the same work. So higher voltage allows much thinner wire. And you have to have excess voltage if you want a clean result.
It is not a new idea, difficult, or a problem.
The military spec has been requiring 24 volts for 50 years.
Uhg, I got to this party late, but I see the same tired arguments continue to play out. The free market failed? Nay, we abandoned the free market and failed.
The argument is made that the free market failed during gas shortages. Can we not consider what role regulations play in creating shortages? Does not the government already manipulate the places that we can seek and extract resources, the number of refineries, and the formulations of fuel that may be sold at different times?
California - posed with a gas shortage - is looking to remove the formulation regulations (temporarily). They say that it won't make much difference in air quality, which if true, begs the question, "then why burden the marketplace with such onerous regulations?!" Were they being dishonest about the value of the regulations when justifying them or now that they are inconvenient?
Taxpayer bailouts of failed business models ... are you stretching your free market model to suggest that this somehow fits? In my world, it is called a command economy when the government controls the levers and switches of business. The free market allows for new management to buy out the resources (factories, labor, etc.) and operate under a new business model.
I do not disagree with your priorities on what is important in a car. I recognize, though, that I cast one vote with my purchase choices. Feel free to lead the charge in educating consumers, but do not blame manufacturers for building what people want to buy.
The 42 volt systems would have been needed for the electrically pre-heated catalytic converters that some idiots wanted to mandate, with the intention that preheating the converter would result in instant conversion. and would eliminate any startup emmissions.
The problem was, and would still be, that it takes a lot more power to pre heat the converter than it does to crank the engine.So dead battery problems would happen a lot more than they do now.
I agree with your thoughts on 42V, William K. It's truly amazing to look back at that period 12 years ago and see how the auto industry, engineering societies and trade magazines were ballyhooing the 42V idea. Now it's gone, and we don't hear a peep about it anymore.
A far better choice than going to the 36 volt (42volts) systems would be TO GET RID OF a whole lot of those stupid things that need so very many wires. We do not need an air conditioning system with three microprocessors and two digital displays, and two processors for the 15way adjustable seats and mirrors. The list goes on and on, and the fact is that the majority of added items don't contribute to good mileage or to occupant safety. They are features that drive up the cost, both to purchase and to repair. Unfortunately they do add weight and mass and so they reduce economy instead.
The high pressure gasoline injection system is interesting, but who is going to service them? and how many will be injured and killed by the high pressure fuel systems? Really, 20,000PSI and even just 10,000 PSI are dangerous pressures, able to send a fine jet of fuel into any of a number of areas where it can do great damage. Working with those pressures IS different and it DOES have a new set of hazards, not to mentionalso a whole new set of problems not yet discovered.
And the high voltage system went the way of independant modules and digital control with the three wire bus, power, data, and ground. It seems that the system was a solution in search of a problem, and the benefits of having all of those parts on one control bus were not able to outweigh the problems experienced in making it work. So now in the car there may be two modules, one for the drive system and one for everything else. My complaint is that when the module fails, which is six months after the warranty ends, it can't be repaired, and the replacement costs $750, if you can get one. And the modules are potted so that they can't be repaired, and all of the failure prone big ICs are custom units that not even Bill Gates could buy, because repair parts are not available, and never were available. So pay $750 and wait three weeks to get your repair part.
So getting rid of the wires by going to 36 or 42 volts won't solve any problem, it will cause many more problems.
We pulled the wiring harness out of a 90's Thunderbrid driver's door and it weighed 35lbs!!! We really need to go to 36vdc nom power to run acessories, etc to reduce weight, copper use along with at least start/stop tech to cut the pure fuel waste.
Present cars only get 7% of the fuel's energy to the road so by getting these parasitic loads off the engine alone can increase mileage 35%.
Also running just 1 power circuit with control modules at each load really cuts copper/wiring weight, costs.
Of course the big weight loss comes from getting rid of metal and going to composite body/chassis like the GM UltraLite and Toyota X-1 showcars.
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