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Hybrid Diesels?



  • goodcrdgoodcrd Posts: 253
    A non-hybrid New Flyer 40' bus in city service gets about 4.1 mpgs and costs about 450K. The engine SEPTA uses is a 8.5 liter Detriot Diesel. A MTA Orion Hybridrive cost $1,000,000+ per copy. Has a 5.9 liter Cummins engine. These two transit authorities, SEPTA (Philadelphia, PA.) And MTA (New York, New York) use Federal and State monies to purchase their vehicles. They must stay within Federal guidelines when ordering vehicles using federal money. And the cities don't have as much say in what vehicles are ordered then what the feds say they can. I think Septa may change the engine they will be specing for their New buses to Cummins due to the lower costs over Detriots. The New Flyer Hybrid at SEPTA is a GM Allison parallel hybrid. Which is more of an electric assist setup. The Orion Hyrid is more of a diesel electric. It uses the Engine to power a generator that powers a traction motor and charges batteries to store electrical power for acceleration. Yes, I agree this Orion is a better Hybrid. But both Hybrids are much less cost effective then trackless trolleys. Trackless trolleys are a true electric bus which get their power from overhead wires. Their draw back has been they "were" limited to no off overhead wire operation. But with the new battery technologies the Trackless trolley should be much more flexible by adding off wire capablity with a battery pack to supply power to get around detours. A Trackless makes no noise and produces "Zero" emissions from the vehicle. This vehicle has been called the Silent Killer because it is so quite people step out in front of it. They never heard it coming!! They Cost about $800,000 a copy. With mpgs at 5.1 and 3.5, fuel costs compared to the costs of these vehicles is not the issue. The added premium for the hybrid is never recovered. It is the reduced emissions produced by these vehicles which is the driving issue for hybrid Mass Transit vehicles. I'd prefer an advanced Trackless Trolley over a Hybrid/Non-Hybrid bus anyday. Oh. SEPTA took their Trackless out of service a few years ago. And thanks for your input. If you like to talk Mass Transit keep it coming. It has been a pleasure posting with you.
  • lensmanlensman Posts: 5
    Hello All,

    Ive been reading this forum for a while now and have a couple of questions:

    1) How efficient are ICEs (either petrol or diesel) in converting the chemical energy in the fuel into mechanical energy at the wheels, if you take into account the clutch/gearbox/drivetrain ?

    2) How much more efficient can a ICE (again either petrol or diesel) be if its designed to run at a constant RPM ?

    This is obviously leading to my personal theory that a series hybrid design with a small very efficient diesel engine running at a constant RPM turning a generator which charges up a battery/electric motor and all the associated regenerative breaking/turning off when the battery is fully charged etc... would be the most efficient design.

    I would love some constructive reasons why this idea wouldn't work, I mean a design encorporating a smaller engine, no clutch or gearbox and possible motors in both wheels at the front or back hence no drive shafts, could result in a car which weights the same if not lighter than a standard setup.

    Thanks in advance.
  • gagricegagrice Pahrump, NevadaPosts: 31,225
    I would love some constructive reasons why this idea wouldn't work,

    I can't think of any. That is the kind of hybrid I have thought should be built from the start. Much simpler and probably more fuel efficient.

    And welcome to the Forum....
  • toyolla2toyolla2 Posts: 158
    Hi Lensman,

    that is a very hard question to answer. Generally speaking optimal efficiency is when variable losses equals fixed losses. An engine running at fixed speed will have a constant frictional loss. On the other hand its variable loss will be dependent on the power it handles.

    Consequently as long as the engine runs at full power (which will be at its top rpm) its efficiency can be made high. But when cruising or decelerating its variable loss (dependent on power) will drop to a low or almost zero value. Meanwhile the fixed loss incurred by having to run at full speed will be maintained and therefore fixed loss will no longer equal variable loss, so mathematically you will start drawing away from your optimal efficiency point.
    The conclusion I derived from all this was that engine speed will have to vary with power demand. You may counter by proposing that the battery can act as a energy buffer so that the engine need only be called upon infrequently when the battery SOC has dropped below 60% say. Here's what you should know about batteries - GM required 840lbs of lead acid to give them enough power density to provide the amps needed by the EV1 for its 0-60mph eight second ramp. Perhaps it would be safe (ie with good longevity) for a Prius 57kw engine 21kw battery if you installed a 400lb NiMH battery and downsized its engine to 15kw. But that would be a $10,000 battery !

    I still believe that series hybrid is the correct approach but without a battery. The advanced hybrid engineering board has some more posts fleshing out the idea.

    Diesel hybrids for cars is a different application than for ships or freight trains where they are more frequently employed. To my knowledge neither ships or trains use batteries for load levelling.

    Cars are what we can describe as being heavily motorised. The huge mass of ships and trains precludes them from attempting to have 0-60mph acceleration ramps in the 8 second range. Since low mass is of great importance, putting a large battery in a light vehicle is a bad idea. Think how much faster the EV-1 would be divested of its 840lb battery. Battery installs are an attempt by vested interests in the resource industries that got shut out when the alchemist for really hi energy chemistries didn't show up and interest for pure electrics waned. They are now trying to hijack hybrid vehicles to adopt their expensive products instead.

    Neither series hybrids nor the Toyota HSD need those large storage batteries as an enabler. It's not just my opinion, it happens to be good physics as well.

    With the battery out of the equation we can consider the diesel. I will start considering diesels for fuel efficiency when I see Boeing start using them in their 747 jumbo jets. Diesels are heavy for their power. Yes lots of torque. If I want torque I'll use a higher ratio in my gearbox. And I hear the VW Jetta TDI is a slug when it comes to acceleration. 'Nuff said.

    For me the real interest is replacing the gearbox/clutch system with a system of higher efficacy where the road wheels are not locked to the crankshaft.

    So when you wrote:
    "I mean a design encorporating a smaller engine, no clutch or gearbox and possible motors in both wheels at the front or back hence no drive shafts, could result in a car which weights the same if not lighter than a standard setup."
    You could have added "and cheaper to boot"

  • gagricegagrice Pahrump, NevadaPosts: 31,225
    Boeing start using them in their 747 jumbo jets.

    Jet "A" is number 1 diesel. That is all we ran in our trucks most of the year in the Arctic. Does not lubricate well so we used 9/11 additive.
  • lensmanlensman Posts: 5
    Thank you all for replying, I knew this board hadnt stagnated!

    Could I ask to clarify a few points you made;

    'GM required 840lbs of lead acid to give them enough power density to provide the amps needed by the EV1 for its 0-60mph eight second ramp'

    Do you mean that you need that much battery to get the car from 0-60mph and then they are flat, or do you mean you need that much in order to provide the PEAK amperage necassary?

    Couldnt the ICE provide enough amperage in conjunction with the battery for the 0-60 sprint? I know Im assuming any power inverter used would have to be made out insanium :) with all this amperage around, but, suppose you were to use a heavy duty high amperage capacitor for those instantanious bursts of speed.

    On a side note was the EV1 a pure serial hybrid, this I didnt know, anyone have any links I could read up about the EV1, tis a real shame GM decided to crush them rather then let interested parties have them, I know the risk of getting sued was one of the reasons sighted, but surely some form of waiver signed by anyone taking the cars would have sufficed...!!!

    Cheers again for the quick replies.
  • gagricegagrice Pahrump, NevadaPosts: 31,225
    was the EV1 a pure serial hybrid

    It was purely electric. The way many of us feel is the best and simplist way to go. When they get batteries that will be adequate. This is a good link covering the GM EV-1 from cradle to graveyard.

  • toyolla2toyolla2 Posts: 158
    I know you are more knowledgeable on fuels than I but if Jet "A" is number 1 diesel. Then why do I smell paraffin when exiting the plane ?
  • toyolla2toyolla2 Posts: 158
    Hi again Lensman,

    Gagrice's link will be useful, but regarding the necessity for 840lbs of lead acid in the EV-1.

    In answer to :

    "you mean you need that much in order to provide the PEAK amperage necessary?"

    Yes you do. However its possible to draw the same current from a lot less lead but risk the possibility of buckling plates and overheating. Few than ten discharges could destroy the smaller pack under those conditions.
    You might note that secondary cells like lead-acid and NiMH have two parameters to look out for.

    1. Power density (the max allowable amps you can draw).
    ie how fast you can accelerate.
    2. Energy density (for how long you can draw those amps).
    ie how far you can go
    When these are known plus the cell voltage and mass per cell you can compute max amps. A subsequent calculation using the energy density parameter and knowing or estimating the current drawn at cruise speed will give you the expected mileage range.

    I apologise if I misled you on the EV1 as a serial hybrid, I was just making a point on how large and expensive the battery was going to be in order to carry a 100kw rating.
  • gagricegagrice Pahrump, NevadaPosts: 31,225
    The only reason I am familiar with this is we took care of the Chevron guys phones. One day I asked what the difference was between Jet A and kerosene. He said not enough to keep you from substituting one for the other. I then asked how cold before they started adding #1 diesel to the tanks for our trucks. He said most of the year they only sell #1 diesel. Also when they drain the Jet A tanks it goes into the diesel for trucks tank. The only difference between Jet A and #1 diesel is certification. I imagine all fuel oil has some paraffin in it.
  • toyolla2toyolla2 Posts: 158
    You enquired

    "Couldn't the ICE provide enough amperage in conjunction with the battery for the 0-60 sprint? I know Im assuming any power inverter used would have to be made out of insanium with all this amperage around."

    Using a battery and ICE together sounds a neat idea initially. It is an idea that is easily grasped by anyone not in the engineering community. Unfortunately it doesn't hold water scientifically. In the long run you would be better off to bore out those cylinders and get your power the old fashioned way or better still raise the ICE towards 15,000 rpm when required, after that you can dispense with the battery entirely and all that energy it was requiring to lug it around the streets. An energy waste that went unquestioned. In the '04 Prius as I have already stated 57kw is augmented by only 21kw so you don't need to do much drilling or speeding up to pick up 21kw from the ICE. And who says the ICE has to be SULEV on a full time basis ? Isn't that an unreasonable engineering restraint given that it's still OK to allow 5.4 litre V8 hemi's on the roads ?

    At 15000 rpm MG1 could generate 45kw (100A @ 450vac)
    and could be direct drive from a gas ICE. A diesel on the other hand cannot speed beyond 4000rpm so would need to be geared up to its generator, incurring gear whine and a 7% transmission loss which counts against its better thermal efficiency that it was selected for in the first place.

    insanium ? Not required. There have been godzilla inverters in the 150hp range for some time. I think the new inverter in the 2007 TCH is rated 105kw so that would put Toyota in a good position to graduate to series hybrid providing the inverters in those vehicles behave. They are also running MG1 and MG2 at 13,000 and 14,000 rpm on that vehicle. All Toyota is missing is a high speed engine. Perhaps Yamaha will help them with that.

  • gagricegagrice Pahrump, NevadaPosts: 31,225
    This year's Challenge X, a Department of Energy and corporate-sponsored advanced vehicle technology competition, pushes university teams to re-engineer their Equinox into a vehicle that is more fuel efficient and cleaner running while maintaining the utility for which the vehicle was originally designed. To meet these goals, the Penn State team has replaced the gasoline V6 engine with a very compact, common rail turbo-diesel engine, according to Matthew Shirk, a graduate student in mechanical engineering and Penn State Challenge X student team leader for this year's competition. The engine is mated to a continuously variable automatic transmission. The engine and transmission are computer controlled, and work together with a powerful electric motor that is powered by a 300-volt lithium ion battery pack.The vehicle is a parallel diesel-electric hybrid with an all-wheel-drive system that works similarly to that found in the stock Equinox.The small engine allows for greater fuel efficiency, while the electric drive components aid the small, less-powerful engine when more power is required.

    Diesel Hybrid challenge
  • toyolla2toyolla2 Posts: 158
    Lensman, things have quietened down since I posted. If you have further questions please indulge.

    Hi Gagrice, I see you have dug up the Challenge X initiative for University students. I can't help feeling that there is not much opportunity for inventiveness when the architecture is so well laid down at the beginning. Looks like a train wreck in the making to me.

    So I'm going to address the title of this group "Diesel Hybrids".
    The first problem is the idea itself. That diesels will be the 'answer' as opposed to other prime movers like gas turbines or wankel engines. It's as if changing the engine can suddenly give improved mileage -if that is indeed the aim of the exercise.

    The real problem is not with the type of engine but the type of transmission it is using. Although mechanical efficiences of mechanical transmissions approach 80% the real parameter we should be looking at is the efficacy not the efficiency of the transmission. Most prime movers exhibit constant torque characteristics. Consequently if the engine is connected temporarily to the wheels via one of five or so different gear ratios the fact is despite whether they are changed manually or automatically, the road wheels are limiting the prime movers ability to reach and maintain its top rpm and hence its maximum power.

    Typically an efficacy of less than 60%is achieved in the real world. The effect of which is to require the capacity of the prime mover to be almost twice as large as it needs to be for a given performance.

    The efficacy of the HCH cvt is difficult to estimate without published graphs and I am not sure any dealership has the equipment to measure how well it does its job either. A diesel hybrid with its low rpm hi torque characteristic would be quite severe on this system incidently.

    The Prius brings its prime mover speed to its max 5000rpm providing the vehicle is in the 50mph to 100mph range.
    The higher torque of a diesel would require merely a change in the 2.6 planetary ratio but would diesel stopping and starting vibration be noticeably reflected through to the vehicle ?

    Anyway 50mph base speed is much too late for a 76Hp engine, at 20mph only 55Hp is available. Allowing MG1 to approach 13,000rpm would bring 76hp sooner at around 30mph and significantly improve efficacy as I have been advocating. Diesel or no diesel.

    How viable would a diesel hybrid be, seeing as how I would incur both hybrid and diesel premiums in the pricing ?
  • toyolla2toyolla2 Posts: 158
    Hi Marcb,

    No, the unvieling of the Peugot diesel hybrid in the UK wasn't old news to me. Being originally from there I would have certainly remembered if I had seen a photo, taken purportedly from there, of a vehicle operating on the wrong side of the road. It is also not a good idea, while in England, to get into the obviously French custom of parking on pedestrian crossings either. Just because pedestrians don't happen to be using them at the time will not be considered a good excuse !
    The Peugot seems to be the first copy of Honda's IMA but with an automatic transmission this time. However I have a feeling that by 2009 the IMA is going to be history.

    Thanks for posting the link
  • gagricegagrice Pahrump, NevadaPosts: 31,225
    I have a question for you if you are from the UK. What happens when you meet in the tunnel under the channel? If the Frenchman is on the Right side and the Brit on the Wrong side, won't they collide?

    On IMA. Why would you think it would go away? The Hybrid Civic is the only hybrid that gets decent mileage at a decent price.
  • When I was in graduate school, we worked on the DOE sponsored Future Car event which was a hybrid vehicle creation competition amongst various universities. I don't recall the exact numbers but the reason the serial hybrid is not so good is due to the multiplication of efficiencies. On a parallel hybrid (PH), you start with chemical energy and convert it to mechanical energy in an ICE (assume this is the same for both a serial and parallel design). In the PH, you then multiply a portion of this by a drivetrain efficiency (the energy going to the wheel). The energy not going to the wheels is then multiplied by a generator efficiency, and then a battery storage efficiency. To use the energy in the battery, there is a battery return efficiency and then a motor efficiency to convert it into rotational energy. The energy that goes from the ICE to the wheels is the most efficient path. On a serial hybrid, the least efficient path is always taken with the fuel conversion efficiency, eneing mechanical efficiency, generator efficiency, battery storage efficiency, battery release efficiency, and then electrical motor efficiency.

    The real beauty of a hybrid is the fact that it can recover the energy typically lost in braking. A diesel hybrid, while attractive from many perspectives is far too expensive to market with the emissions requirements what they are today, the aftertreatment and the hybrid system costs are too much for the average consumer to recoup over the life of the vehicle.
  • toyolla2toyolla2 Posts: 158
    "What happens when you meet in the tunnel under the channel? " Well, regarding the English Channel tunnel... no one can drive through the 'chunnel' cars are transported through by rail !

    "On IMA. Why would (I) think it would go away? "
    Mechanical CVT's were discarded by industry in the early seventies due to reliability issues. Possibly lack of maintenance. Anyway, downtime expenses incurred while they were being repaired after a failure prompted industry to search out a more robust method. SCR follower drives were found to be a viable replacement. I know this because I joined the electronic drive business around this time and was occasionally sent out to commission this type of application.

    Regarding the HCH, it appears that dealership mechanics are being encouraged to replace the whole gearbox rather than the cheaper but riskier (to the service dept) replacement of a specific part which would then demand more critical set up skills. All the reading I have done never mentions a specific part to be identified as the culprit, it's always replacement of the whole subsystem when replacing transmission fluid was found to be ineffective. Perhaps someone could straighten me out on this.
    The more predictable Prius system with its low wear planetary torque splitter seems to be the way to go. I don't think that anyone will try argue with me that mechanical CTV MTBF's are superior to the MTBF's of the equivalent Prius electronic power modules. That being said, I am surprised the Peugot diesel didn't attempt a THS approach.
  • toyolla2toyolla2 Posts: 158 the fact that it can recover the energy typically lost in braking.

    No , that fact is not beautiful at all, gearhead_greg,
    and since I am denied the pleasure of your private e-mail I suggest that you move the first paragraph of your post over to the Advanced Hybrid board where I can deliver to your academic ivy walled idea of a serial hybrid the skewering it deserves - but in a nice way !
  • Anybody going to hybridfest?

    Sounds like a big event and I heard they have a hybrid diesel for you to mull over.
    Lots of things to do and see, people are attending from all around the country and Canada.

    Hope to see you there!
This discussion has been closed.