I'm confused. When I see a Prius holding up traffic on I-5 halfway between Seattle and Vancouver I assume that the battery is depleted and that its gas engine is maxed-out.
Then I hear that " HSD full hybrid use the electric motor and the generator even on the highway. The battery pack is also used when passing or cruising on the highway."
So, now its still powered by the battery at 70MPH and 70 miles from home. That's possible for a full electric, but ...
But there is a claim that the battery is only 99 pounds. There are guys at the local university who have won world championships for electric cars who would love to know how you take a 3,000 pound street-legal car and drive an hour on the highway at 70 MPH with a 99 pound battery. If you could do that, then dump that 1.5 liter gas engine and go full-electric. You'll reduce emissions and weight at the same time! ... it would be nice if it were possible, but...
And the point about a full hybrid elliminating the need for a transmission only applies to a series hybrid, not a parallel hybrid, and unless you work for Santa Fe Railroad or such, you probably don't have the opportunity to drive a series hybrid.
Yes, a series hybrid (like a locomotive, or the new highway trucks) has the advantage of no transmission. In reality, the generator/electric-motor is the transmission. But it has the disadvantage that the engine must be large enough to provide all the power used. Its OK for a train where taking 1/2 hour to reach cruising speed is acceptable, but I don't think that level of performance will catch on, especially in North America. (to be more exact, the engine, the generator, and the electric motors ALL must carry the full power load. The result is a huge increase in weight. The gain is in reducing frictional losses by ditching the mechanical transmission. But the weight of the propulsion system is small in comparison to the cargo, and you're also aware that trains don't stop for traffic lights every few blocks
The parallel hybrid has the disadvantage of a transmission (yes, your beloved Prius has a transmission), but the advantage that power can come from electric and ICE engines at once, which helps minimize both, hence the potential for a 99-pound battery pack. (which, on its own, will barely get you past the edge of town)
But the point is, you can't have everything at once .... there are tradeoffs.
In the end, the hybrid is a compromise between a pure electric vehicle and an ICE vehicle. If efficiency is the goal, then diesel makes more sense than gas for the ICE component in a steady-state situation. But for vehicles that accelerate and deccellerate often, the reduced weight of a non-turbo gas engine could make sense compared to the extra weight of a turbo-charged diesel. Taken to the extreme though, you can ditch the engine and go full electric with regenerative braking.
And for those who travel on the highway mostly (where there are no big hills to offer opportunities for regenerative braking) the turbo diesel without the weight of the additional hybrid stuff could make the most sense.
What you get with a hybrid is a compromise: - a much longer range that a pure electric vehicle - better mileage in stop & go traffic than a pure ICE
If you drive short distances the pure electric might be best (note the proliferation of electric golf-carts) and if you tend to drive long distances the turbo-diesel might be best. But if your needs lie in the middle and neither of these meet your needs, then the hybrid is possibly your best chance to get around and help reduce fuel consupmtion. There are just those issues of the materials used in the batteries and motors to clean up (and in all car component manufacturing)
That's where low-energy recyclible materials like good old iron beat all others. But maybe that's another topic?...
What you get with a hybrid is a compromise: - a much longer range that a pure electric vehicle - better mileage in stop & go traffic than a pure ICE
I don't think there is a way around compromises, diesel, gasoline or hybrid. That said, you could actually add a third line to this, as demonstrated by Accord Hybrid specifications....
- better mileage on highway as well. In a way, this is being achieved by combining VCM (variable cylinder management) and electric assist. Under light acceleration on a highway, the electric motor will provide boost to the three cylinders (without having to activate the other three).
So, under light throttle, Accord Hybrid will be powered by an equivalent of 1.5/I-3 with electric assist. It is only under moderate to heavy acceleration need will all six cylinders come alive.
Is this technology currently in use on any of the Honda vehicles? I think that is one of the real selling points of the new Chrysler cars. Not sure exactly how it works.
That sounds great. But when you said "- better mileage on highway as well" you meant compared to a gas Accord, not a TDI I presume???
But this is very interesting. I average 53 MPG overall with my turbo-diesel, and I've had it over 115 MPH a couple times (don't know what the top speed is and don't need to find out) but the engine is obviously larger than it needs to be ... so I wonder what kind of mileage I could get if they built a T-D engine that cut off 1/2 the cylinders when cruising?
[note: 53 miles to a Canadian gallon: about 47 MPG US combined mileage with a lead-foot]
Has anyone seen any diesel engines with cylinder cut-out schemes?
It works by closing down the intake and exhaust valves on one bank of cylinders. Pistons still move, only difference is that there is no combustion involved. This (supposedly) helps improve fuel economy by 12%. VTEC is used to control VCM.
Honda has used VCM in Japanese market for a year (Honda Inspire which is basically American Accord V6 with some cosmetic changes, and Acura TSXesque interior). A variation of VCM has been in use in Civic Hybrid for couple years now (in this case, three of four cylinders are deactivated, but only during deceleration).
Changing definitions to your advantage won't work.
The PSD in Prius never disengages. It is always engaged. That fact alone is enough to disqualify it from being called a "transmission" by the automotive industry's definition.
The act of transmitting power alone is not enough. If it was, the driveshaft & differential could be called a "transmission" too. But they aren't.
And wouldn't you know it, taking a close look at the PSD you'll discover it is actually nothing more than just a differential. All it does is transfer power, the very same purpose as a differential.
There is no shifting of any kind either, nothing at all related to gearing... which has been the very purpose of a "transmission" for decades. Prius doesn't have that. No part inside adjusts size ratios of any kind, not like a manual, an automatic, or a cone & belt CVT. Power carriers are all that's literally there, just like in a differential.
Face it. Toyota eliminated the transmission, a true overall cost saving strategy... as well as being a way of reducing vehicle complexity & maintenance.
I don't own a Prius, so I looked on the WEB. Toyota's site says that it has a Continuously Variable Transmission (CVT). Edmunds specs also state CVT.
The review on Edmunds states: "The Prius uses an electronically controlled continuously variable transmission (ECVT) which helps deliver high gas mileage. It feels a little strange the first time you start up, since the engine revs to a certain level and stays there. It almost feels like the transmission is slipping. However, this quickly seems normal and is replaced by the impression of smoothness as the car accelerates."
All of this information seems to indicate a transmission is there.
But I like the PSD stuff on Toyota's site. It appears that it automatically switches between being a series hybrid at low speed (taking advantage of the huge torque of the electric motor) and a parallel hybrid at high speed, making use of the gas-engine's high-rev power.
> All of this information seems to indicate a transmission is there.
Clearly, your definition of "transmission" does not match the industry standard. That's ok, since the "CVT" most people know is *NOT* what Toyota uses despite using the "CVT" label. In fact, there is not a single piece within that is the same.
If you'd like to contribute a new definition, feel free. The industry is rather outdated anyway. So they are overdue for change.
The point still holds. It is always engaged, no gears exist, and nothing ever shifts. There are just carriers that rotate.
Well, John, Toyota mentions electronically controlled CVT as Prius' transmission, doesn't it?
CVTs don't have to use gears, just a way to continously vary drive ratio that can enable translation of a constant engine speed to increasing (or decreasing) wheel speed.
This may have gotten posted before. It gives a simple explanation of how the Prius ECVT gets power to the wheels. I found it easy to read and understand.
> Has anyone seen any diesel engines with cylinder cut-out schemes?
I would think it would be superfluous; just don't spray fuel in that bank.
In gas engines, there's a limit to how lean you can make the mixture before it won't burn properly. In a diesel, that won't happen; because there's no "flame front" to be interrupted.
So, there's much less to be gained by cutting out cylinders. You would achieve some gain in fuel economy if you kept the valves closed, because this would reduce some pumping loss, but it might be just a few percentage points, which might not compensate for the extra complexity/weight. There's probably other, cheaper, gains to be made.
It's different in the honda gas engines because VTEC already supplies most of the hardware needed to do this. I don't know of any diesel with VVT. No point when you're always between 1000 and 3000 RPM.
I notice the new audi turbos are using gas direct injection, because they can use high boost with high compression ratios. Sounds familiar.
> just a way to continously vary drive ratio that can enable translation of a constant engine speed to increasing (or decreasing) wheel speed.
That is not how this type of CVT works. There is an extra component involved, which does not exist in that type you describe. Varying power is redirected without the wheel speed changing.
So to be clear, reusing an existing label (CVT) or category (transmission) will only lead to confusion. The official term is "Planetary CVT". Why not use that?
"And the point about a full hybrid eliminating the need for a transmission only applies to a series hybrid, not a parallel hybrid, ...."
Did you know that there is a third type of hybrid? It is a combination of series and parallel That is what Hybrid Synergy Drive is all about. It inherit advantages of both series and parallel hybrid designs. Internal combustion work together with electric motors to eliminate each other's disadvantages.
HSD does not have a traditional transmission. Dual powertrain is capable of variable power output to drive the car without ever needing shifting a gear! Check out Car And Driver's Top gear acceleration from 50-70mph of Prius and compare that to your favorite traditional car.
The only thing that diesel has over hybrid is lower fuel price in Europe. As emission requirements become more strict, diesel cars get more expensive and lower mpg. In contrast, hybrids drop in price and gain mpg as they get more efficient. I am for diesel hybrids because modern diesels(D-CAT) are cleaner than traditional gas engines. If diesel go diesel-hybrid, it'll be even cleaner than gas-electric. Unfortunately, the industry is not ready for diesel-hybrid yet, I don't think. Gas-electric needs to take off first to mature hybrid technology and cost. Then diesel-hybrid can come in with additional cost.
Oh, BTW, let me make some silly examples so you can see what I am talking about HSD easier. In the city driving, Prius can act like a 75% series / 25% parallel hybrid. On the highway, it can also transform it's powertrain to act like 25% series / 75% parallel. You might be wondering how can that be? The key is the Power Split Device. By electronically controlling where the power from ICE gets split(and how much) HSD can dynamically transform it's powertrain to take the most advantage of any situation. It is extremely flexible.
After you digest all those information, you can think why Prius still need electric drivetrain on the highway. And then think why Prius only need such a small (1.5kW) 99lbs battery.
"Has anyone seen any diesel engines with cylinder cut-out schemes?"
Nope. Diesel would not benefit much from disabling cylinder as it's combustion is already efficient. Pumping loss and other Otto cycle related problems had been minimized with Atkinson cycle and VCM.
I didn't think there'd be much gain, but it seems to work for Chrysler's 300. If you just cut fuel you get extra oxygen in the exhaust which might overheat the catalytic converters. I believe that extra air is used to clean out the particulate traps on the new cars.
RE AUDI FSI Engines: "sounds familiar" -- yes indeed! Sounds like a diesel engine modified to run on gasoline. Does it still need spark-plugs after it starts?
I didn't think there'd be much gain, but it seems to work for Chrysler's 300. If you just cut fuel you get extra oxygen in the exhaust which might overheat the catalytic converters. I believe that extra air is used to clean out the particulate traps on the new cars.
RE AUDI FSI Engines: "sounds familiar" -- yes indeed! Sounds like a diesel engine modified to run on gasoline. Does it still need spark-plugs after it starts?
I guess all the "CVT" talk is coming from marketing. As usual, their "dumbing down" of all things technical just creates confusion!
That's a really cool system! I'm sure the new Prius must be a quantum leap ahead of the first one in performance.
But I still don't totally agree with this: " The only thing that diesel has over hybrid is lower fuel price in Europe."
Diesel still represents better utilization of resources (crude oil), can be synthesized easily (bio-diesel), and still makes more power per pound than gasoline. However, I'll bet the gas engine in the Prius (running at optimum speed) comes as close to diesel as you can get, reducing that gap considerably.
I'd like to see this HSD drivetrain with VW's 1.4-liter TDI from the 80+MPG LUPO replacing the gas engine. I'd expect 5% to 10% mileage gains over the gas Prius. Of course, it won't match the Lupo, but that vehicle won't carry 5 adults in it either.
An interesting feature of the Lupo is that it has a fairly traditional 5-speed manual transmission but no clutch pedal. The transmission is shifted by a computer instead so it can pick ideal shift-points for optimum mileage.
The Lupo and Prius both indicate that regardless of fuel or drivetrain, electronics will play an important part of future drivetrain optimizations.
"If you just cut fuel you get extra oxygen in the exhaust which might overheat the catalytic converters. I believe that extra air is used to clean out the particulate traps on the new cars."
Hmmm--i can see that if there were a lot of hydrocarbons in the exhaust the extra o2 would make them hotter, but if the engine is properly lean it shouldn't. In fact it might make them too cool, if there's too much air blowing through them?
I know that with some gas engines, extra air is blown into the exhaust to allow hydrocarbon combustion. And with some turbo engines when boost is high, LOTS of gas is dumped into the mix to avoid detonation due to the heat/pressure. Neither of these ought to apply to diesel.
As for the FSI, the spark plus is still used, but when we want to run "lean" instead of throttling the intake, we spray just a little puff of fuel next to the spark plug. So the point is that the engine can be run with the throttle wide open reducing pumping losses. They also point out that you can create a layer of air insulating the charge from the cylinder walls, reducing leat loss. Clever stuff.
Sort of like diesel, except not quite as efficient, but we can rev to higher RPM's.
Bring the diesel cars to America. I'll buy one and test the air. I think it is all hype by the oil and auto industry. Why sell a car that lasts twice as long and only uses 2/3 the fuel? How many MB diesels are still on the road compared to a gas version of the same car?
It is a fact that the oil industry has had too much control over this country for the last 100 years. Diesel can be made from coal or grain. Which we have a lot of.
ASTHMA is a rapidly growing problem, which is contributed heavily to by SMOG related emissions. In fact, that point is so well proven that the list of things to do to reduce asthma problems includes the recommendation move away from SMOG plagued areas.
So there is nothing for you to test. Just look up the EPA values with respect to SMOG emissions (NOx, HC, and PM).
It is true that diesels put out more particulates and nox than a gas motor of the same age. However, one must have some perspective.
Vehicles contribute less than 24% of the smog in the major 25% U.S. cities (Dan Meszler). Add to that that many of the major smog contributing vehicles are old out-of-tune vehicles. A new diesel, particularly (pun intended) one running on biodisel or ULSD is going to pollute less than a gasoline engine of all but quite recent vintage. The reality is that any new diesel car is not going to negatively impact smog.
That doesn't account for the extra hydrocarbon emissions of gasoline vs diesel in storage, etc. Personally, i'd wager that the bulk of the hydrocarbons my car puts into the atmosphere is during the fueling process when i see vapors coming out of the tank, or some gasoline spills on the ground. I think my car smogged a 9ppm for hydrocarbons. Add spills and emissions at various stages of the extraction and shipping processes, and you've really got something.
No, i think trying to chase down that last few percentage points of emissions is a bit of a red herring. Moderns cars are already damn good. A 2 stroke lawn mower run for any period of time is going to pump more junk into the atmosphere than a well-tuned newer car. We'd be better off environmentaly pulling a old smoke belcher off the road instead of replacing 10 modern cars with hybrids. And, again, cars contribute to only 24% of the smog already.
That's why i think it's important to examine total lifecycle emissions, environmental impact, resource use, and energy consumption. That's where i still think diesel has the advantage. Longevity, lower manufacturing impact ( simpler, no special battery pack ) and a fuel with a lower environmental impact.
That's interesting. There are fewer diesel cars today than during the 80s. Must be the hybrids causing the problem. Or maybe the pollen from growing more corn to make Ethanol. THERE is no proof that a modern diesel is causing those problems. You are ignoring facts and making up theories. You need to read the whole article. Is asthma increasing in Europe where they are moving toward 50% diesel cars?
True. But to say that there is no transmission involved in Prius is a false statement. And to suggest that Toyota eliminated a part of a typical drive train (transmission) is as well. Well, in the traditional sense, yes, but it has been replaced by another.
And the official term is eCVT, isn’t it? Toyota’s website mentions that.
"NRC estimates that 10 percent of the cars are producing 50 percent of the harmful exhaust emissions that lead to smog and ground level ozone. This has been confirmed by other tests and surveys over the years as well."
There's a lot more, but i'd have to go home and link magazine articles for most of the sources i know.
Consider too: as i mentioned my 6 year old car with the the 2.8: i-6 smogged at under 10PPM for hydrocarbons. I also average ~27mpg ( lots of highway ) and put on ~12KMPY. I crunched out that this means the tailpipe put out about .05 liters of hydrocarbons over the course of last year. I'm sure that more than that has been emitted in spills, tank vapors, etc. And consider gasoline being used as a solvent/cleaning agent, as is often done.
I can see a coal-burning powerplant from my office window. Nice big plume of smoke.
No, i think that as long as cars are fairly modern and in tune, pollution differences are marginal in difference. Resource consumption is the real concern--oil to be extracted from the ground, metals mined, etc.
I think this emissions is the focus, becuase it's easier to improve emissions and sell new cars this way than to get people thinking about the used resources. That might get them to scrupulously maintain their old cars which is probaly better, all told, than letting it going to pot and buying a whizz-bang new "clean" car.
Extremism doesn’t help in deriving a logical point. That’s something I see in articles that deal with such subjects. The only way I would find these claims, from both sides, valid if they could throw comparisons that are comparable. What if 50% of vehicles were powered by “clean” diesels? Would their six times greater particulate emissions be a greater threat than their impact on global warming or smog formation?
And this leads us back to the general difference in culture as well. According to the second article (I ignored the first since lawn mower emissions could be discussed separately), Europeans don’t care about emissions that contribute towards smog formations as much as they do against green house emissions. Still, wouldn’t it be logical to put this in a perspective? Does a clean gasoline engine (say, 100 HP) produce more green house emissions than a comparable diesel engine? And we could go beyond vehicular emissions to everything else if we had the data, but comparable to make sense.
UK market Civic... emissions: Hybrid CO2 Emissions (g/km): 116
Diesel CO2 Emissions (g/km): 134
Based on this, it appears that hybrid is not only better in emissions contributing towards smog, but also beats a comparable diesel engine in terms of green house emissions (at least the measure that is readily available at this time).
> The reality is that any new diesel car is not going to negatively impact smog.
Sorry, but even a 0.00001% percent increase is a problem. Multiply that times the 60,000,000 new vehicles sold worldwide each year and the number becomes a reality with a lot of people suffering from breathing-related problems.
Just because one polluting source contributes less than another is not a reason for exemption. Every little bit really does make a difference... especially when the population is growing rapidly and driving time continues to increase.
> i'd wager that the bulk of the hydrocarbons my car puts into the atmosphere is during the fueling process when i see vapors coming out of the tank
Fortunately, my Prius doesn't. It has a bladder in the tank that significantly reduces evaporative emissions.
> Moderns cars are already damn good.
Again, amplified times 60,000,000 negates that claim.
If all 60,000,000 of those cars were in your neighborhood, then I'd agree you would have a problem. Fortunately for us they are spread across the planet. The planet can handle it.
"True. But to say that there is no transmission involved in Prius is a false statement. And to suggest that Toyota eliminated a part of a typical drive train (transmission) is as well. Well, in the traditional sense, yes, but it has been replaced by another."
Did you realize that the parts that are replacing the traditional transmission are also required fundamental parts of a full hybrid? Without those parts, HSD wouldn't be a hybrid drivetrain. ECVT is a by-product of Synergy effect of the two drivetrains.
Synergy: The interaction of two or more agents or forces so that their combined effect is greater than the sum of their individual effects.
I don’t disagree. I picked up the following argument from John
“Face it. Toyota eliminated the transmission, a true overall cost saving strategy... as well as being a way of reducing vehicle complexity & maintenance”
A traditional automatic transmission has thousands of parts in it. HSD is mechanically more simpler. HSD does not have belts, pulley, and other misc. parts attached to it. And yes, HSD has much more reliable parts than traditional cars do.
The point wasn’t about counting parts that contribute to “any” kind of transmission. We have been there before, so anything going forward will be repetitive. Give me a manual transmission over CVT, CVT-7, eCVT, 3/4/5/6/8 speed automatic transmission or clutchless manual anyday.
"Sorry, but even a 0.00001% percent increase is a problem. Multiply that times the 60,000,000 new vehicles sold worldwide each year and the number becomes a reality with a lot of people suffering from breathing-related problems."
That argument is absolutely absurd. If there's a .000001% increase there's going to be a .00001% increase in smog. Multiplying by the total vehicles produced gives you come constant figure across the whole planet.
This also leads to consideration of the manufacturing impact, as long as you're considering the whole planet's emissions. Diesel wins on this count: simpler systems, longer lasting, less to replace.
"Fortunately, my Prius doesn't. It has a bladder in the tank that significantly reduces evaporative emissions."
When you fill the tank, there is going to be some air displaced, the same goes for the gas station tank, shipping, etc.
Frankly, your arguments seem geared toward defending the prius, not the environment.
The basis of your argument about Toyota's eCVT term is that Toyota needed a way to explain how HSD works to the general public, which only knows in term of traditional transmission.
Let's say an electric car can come to a stop with regen braking, without any brake pads being installed. What kind of brake does that electric car has? eBrake? You can say, since eBrake is a type of brake, then this electric car must have a brake.
But an electric car only has a electric motor that can also act as a generator to stop itself. It does not have a traditional brakes. The best thing is to stay away from traditional "labels" and dwell on it. This is exactly what is happening with eCVT argument.
> Frankly, your arguments seem geared toward defending the prius, not the environment.
That perception doesn't change reality.
To be certified as PZEV, the vehicle must significantly reduce evaporative emissions. To do this, the automakers have been placing bladders in the tanks.
I use Prius as the example all the time because everyone jumps all over me when I sight yet-to-be released HSD vehicles or speak in general about HSD itself... Damned if you. Damed if you don't.
Sorry, but even a 0.00001% percent increase is a problem. Multiply that times the 60,000,000 new vehicles sold worldwide each year and the number becomes a reality with a lot of people suffering from breathing-related problems.
You have shown absolutely no data to substantiate your claim. If asthma is increasing in Minnesota, better look at the ethanol. That is why CA is fighting to keep that horrid stuff out of our gas. It may be more of a health hazard than diesel. And not near as safe to handle. Furthermore the decreased mileage you get with 10% -15% ethanol negates any advantage it has as far as helping us reduce foreign oil consumption. Face it diesel IS the answer for cutting back on foreign oil and bio-diesel may be able to cut it even further. Show us some legitimate tests on modern diesel car engines that substantiate your claims & assumptions.
More than 60 million people in America have asthma or allergies, costing the U.S. economy over $20 billion each year in hospitalizations, medical services, lost productivity at work or school, and more.
When you read about the contributing factors, you'll see that smog is listed. And we all know there is an absolutely overwhelming amount of data documenting the variety of problems smog causes... including breathing related problems, and the reduction/elimination of federal road-improvement funding.
NOx emission increase with Biodiesel, not decrease.
B100 is even dirtier than diesel. It's less efficient and more expensive too. And it is worthless in the winter. Only B20 can be used, and even then it requires an additive which will add to the cost.
I don't need to. The data is so absolutely overwhelming you can find it everywhere.
Maybe overwhelming to you. Not to a scientific mind that wants facts. I think 59.99 million of those people are victims of tobacco smoke. I can tell you for a fact I breath better in Los Angeles today than in 1957 when we moved from there to San Diego. I say those asthma & allergy victims are barking up the wrong tree by chasing auto emissions.
As usual you did not address the issue. The issue is "tests on modern diesel car engines". Find that overwhelming evidence, not some vague website that has an agenda, and no substantiating evidence pertaining to modern diesel car engines.
B100 is even dirtier than diesel. It's less efficient and more expensive too. And it is worthless in the winter. Only B20 can be used, and even then it requires an additive which will add to the cost.
Again more rhetoric with no substantiation. You forget that over half the people live where it rarely hits 20 degrees. And it is easy to add petroleum based diesel to compensate. It is the closest thing we currently have to a 100% renewable source of energy.
"More than 60 million people in America have asthma or allergies, [snip]When you read about the contributing factors, you'll see that smog is listed."
For asthma, yes.
There's no evidence that modern diesels will contribute to smog more than a modern gas car, including hybrids.
Yes, we all know the NoX is a bit higher, but as we already know cars are already only 24% of smog sources, and the bulk of those are older problem cars.
There's no evidence that modern diesels will contribute to smog more than a modern gas car, including hybrids.
That is where I am at in this research. Nothing shown here is even close to conclusive that diesel is as bad as gasoline at causing smog. If you are real concerned as I am you can find BP ECD-1 diesel in most civilized communities in this country. It is either less than 15 or 30 PPM sulfur. That all but eliminates the NoX that is always thrown in the face of people that are educated enough to know that diesel is a better way to save oil than any current gas powered vehicle.
We had more particulate matter in the air here in So. California during the big fires than all the cars in this state produce in a hundred years. Where were the greenies then. It was their fault the fires happened. They stopped the forest service from clearing thousands of acres of trees that were dead from a beetle infestation. Several people including my brother, have come down with asthma type symptoms since that fire. And we have the toughest regulations in the country. Don't get me started.
Dave, You noticed when I asked for solid evidence that modern diesel engines were a problem, certain folks hid in the barn. They are good at dishing out misinformation, short on scientific evidence.
Comments
Establishing realities for both camps. What do you think the post I replied to, suggested?
Then I hear that " HSD full hybrid use the electric motor and the generator even on the highway. The battery pack is also used when passing or cruising on the highway."
So, now its still powered by the battery at 70MPH and 70 miles from home. That's possible for a full electric, but ...
But there is a claim that the battery is only 99 pounds. There are guys at the local university who have won world championships for electric cars who would love to know how you take a 3,000 pound street-legal car and drive an hour on the highway at 70 MPH with a 99 pound battery. If you could do that, then dump that 1.5 liter gas engine and go full-electric. You'll reduce emissions and weight at the same time!
... it would be nice if it were possible, but...
And the point about a full hybrid elliminating the need for a transmission only applies to a series hybrid, not a parallel hybrid, and unless you work for Santa Fe Railroad or such, you probably don't have the opportunity to drive a series hybrid.
Yes, a series hybrid (like a locomotive, or the new highway trucks) has the advantage of no transmission. In reality, the generator/electric-motor is the transmission. But it has the disadvantage that the engine must be large enough to provide all the power used. Its OK for a train where taking 1/2 hour to reach cruising speed is acceptable, but I don't think that level of performance will catch on, especially in North America.
(to be more exact, the engine, the generator, and the electric motors ALL must carry the full power load. The result is a huge increase in weight. The gain is in reducing frictional losses by ditching the mechanical transmission. But the weight of the propulsion system is small in comparison to the cargo, and you're also aware that trains don't stop for traffic lights every few blocks
The parallel hybrid has the disadvantage of a transmission (yes, your beloved Prius has a transmission), but the advantage that power can come from electric and ICE engines at once, which helps minimize both, hence the potential for a 99-pound battery pack. (which, on its own, will barely get you past the edge of town)
But the point is, you can't have everything at once .... there are tradeoffs.
In the end, the hybrid is a compromise between a pure electric vehicle and an ICE vehicle. If efficiency is the goal, then diesel makes more sense than gas for the ICE component in a steady-state situation. But for vehicles that accelerate and deccellerate often, the reduced weight of a non-turbo gas engine could make sense compared to the extra weight of a turbo-charged diesel. Taken to the extreme though, you can ditch the engine and go full electric with regenerative braking.
And for those who travel on the highway mostly (where there are no big hills to offer opportunities for regenerative braking) the turbo diesel without the weight of the additional hybrid stuff could make the most sense.
What you get with a hybrid is a compromise:
- a much longer range that a pure electric vehicle
- better mileage in stop & go traffic than a pure ICE
If you drive short distances the pure electric might be best (note the proliferation of electric golf-carts) and if you tend to drive long distances the turbo-diesel might be best. But if your needs lie in the middle and neither of these meet your needs, then the hybrid is possibly your best chance to get around and help reduce fuel consupmtion. There are just those issues of the materials used in the batteries and motors to clean up (and in all car component manufacturing)
That's where low-energy recyclible materials like good old iron beat all others. But maybe that's another topic?...
- a much longer range that a pure electric vehicle
- better mileage in stop & go traffic than a pure ICE
I don't think there is a way around compromises, diesel, gasoline or hybrid. That said, you could actually add a third line to this, as demonstrated by Accord Hybrid specifications....
- better mileage on highway as well. In a way, this is being achieved by combining VCM (variable cylinder management) and electric assist. Under light acceleration on a highway, the electric motor will provide boost to the three cylinders (without having to activate the other three).
So, under light throttle, Accord Hybrid will be powered by an equivalent of 1.5/I-3 with electric assist. It is only under moderate to heavy acceleration need will all six cylinders come alive.
Is this technology currently in use on any of the Honda vehicles? I think that is one of the real selling points of the new Chrysler cars. Not sure exactly how it works.
That sounds great.
But when you said "- better mileage on highway as well" you meant compared to a gas Accord, not a TDI I presume???
But this is very interesting. I average 53 MPG overall with my turbo-diesel, and I've had it over 115 MPH a couple times (don't know what the top speed is and don't need to find out) but the engine is obviously larger than it needs to be ... so I wonder what kind of mileage I could get if they built a T-D engine that cut off 1/2 the cylinders when cruising?
[note: 53 miles to a Canadian gallon: about 47 MPG US combined mileage with a lead-foot]
Has anyone seen any diesel engines with cylinder cut-out schemes?
It works by closing down the intake and exhaust valves on one bank of cylinders. Pistons still move, only difference is that there is no combustion involved. This (supposedly) helps improve fuel economy by 12%. VTEC is used to control VCM.
Honda has used VCM in Japanese market for a year (Honda Inspire which is basically American Accord V6 with some cosmetic changes, and Acura TSXesque interior). A variation of VCM has been in use in Civic Hybrid for couple years now (in this case, three of four cylinders are deactivated, but only during deceleration).
Changing definitions to your advantage won't work.
The PSD in Prius never disengages. It is always engaged. That fact alone is enough to disqualify it from being called a "transmission" by the automotive industry's definition.
The act of transmitting power alone is not enough. If it was, the driveshaft & differential could be called a "transmission" too. But they aren't.
And wouldn't you know it, taking a close look at the PSD you'll discover it is actually nothing more than just a differential. All it does is transfer power, the very same purpose as a differential.
There is no shifting of any kind either, nothing at all related to gearing... which has been the very purpose of a "transmission" for decades. Prius doesn't have that. No part inside adjusts size ratios of any kind, not like a manual, an automatic, or a cone & belt CVT. Power carriers are all that's literally there, just like in a differential.
Face it. Toyota eliminated the transmission, a true overall cost saving strategy... as well as being a way of reducing vehicle complexity & maintenance.
JOHN
I don't own a Prius, so I looked on the WEB.
Toyota's site says that it has a Continuously Variable Transmission (CVT).
Edmunds specs also state CVT.
The review on Edmunds states: "The Prius uses an electronically controlled continuously variable transmission (ECVT) which helps deliver high gas mileage. It feels a little strange the first time you start up, since the engine revs to a certain level and stays there. It almost feels like the transmission is slipping. However, this quickly seems normal and is replaced by the impression of smoothness as the car accelerates."
All of this information seems to indicate a transmission is there.
But I like the PSD stuff on Toyota's site.
It appears that it automatically switches between being a series hybrid at low speed (taking advantage of the huge torque of the electric motor) and a parallel hybrid at high speed, making use of the gas-engine's high-rev power.
Very clever and intelligent engineering.
I presume that the CVT is integrated into the differential and is the "2-gears" drawing in the image on Toyota's site?
http://www.toyota.com/vehicles/2005/prius/key_features/hybrid_syn- _drive.html
Brian
Clearly, your definition of "transmission" does not match the industry standard. That's ok, since the "CVT" most people know is *NOT* what Toyota uses despite using the "CVT" label. In fact, there is not a single piece within that is the same.
If you'd like to contribute a new definition, feel free. The industry is rather outdated anyway. So they are overdue for change.
The point still holds. It is always engaged, no gears exist, and nothing ever shifts. There are just carriers that rotate.
JOHN
CVTs don't have to use gears, just a way to continously vary drive ratio that can enable translation of a constant engine speed to increasing (or decreasing) wheel speed.
http://home.earthlink.net/~graham1/MyToyotaPrius/Understanding/Co- ntinuouslyVariableTransmission.htm
I would think it would be superfluous; just don't spray fuel in that bank.
In gas engines, there's a limit to how lean you can make the mixture before it won't burn properly. In a diesel, that won't happen; because there's no "flame front" to be interrupted.
So, there's much less to be gained by cutting out cylinders. You would achieve some gain in fuel economy if you kept the valves closed, because this would reduce some pumping loss, but it might be just a few percentage points, which might not compensate for the extra complexity/weight. There's probably other, cheaper, gains to be made.
It's different in the honda gas engines because VTEC already supplies most of the hardware needed to do this. I don't know of any diesel with VVT. No point when you're always between 1000 and 3000 RPM.
I notice the new audi turbos are using gas direct injection, because they can use high boost with high compression ratios. Sounds familiar.
dave
That is not how this type of CVT works. There is an extra component involved, which does not exist in that type you describe. Varying power is redirected without the wheel speed changing.
So to be clear, reusing an existing label (CVT) or category (transmission) will only lead to confusion. The official term is "Planetary CVT". Why not use that?
JOHN
Did you know that there is a third type of hybrid? It is a combination of series and parallel That is what Hybrid Synergy Drive is all about. It inherit advantages of both series and parallel hybrid designs. Internal combustion work together with electric motors to eliminate each other's disadvantages.
HSD does not have a traditional transmission. Dual powertrain is capable of variable power output to drive the car without ever needing shifting a gear! Check out Car And Driver's Top gear acceleration from 50-70mph of Prius and compare that to your favorite traditional car.
If you want to learn more about parallel-series hybrid, go to the source that I learned from.
http://home.earthlink.net/~graham1/MyToyotaPrius/Understanding/Co- ntents.htm
The only thing that diesel has over hybrid is lower fuel price in Europe. As emission requirements become more strict, diesel cars get more expensive and lower mpg. In contrast, hybrids drop in price and gain mpg as they get more efficient. I am for diesel hybrids because modern diesels(D-CAT) are cleaner than traditional gas engines. If diesel go diesel-hybrid, it'll be even cleaner than gas-electric. Unfortunately, the industry is not ready for diesel-hybrid yet, I don't think. Gas-electric needs to take off first to mature hybrid technology and cost. Then diesel-hybrid can come in with additional cost.
Oh, BTW, let me make some silly examples so you can see what I am talking about HSD easier. In the city driving, Prius can act like a 75% series / 25% parallel hybrid. On the highway, it can also transform it's powertrain to act like 25% series / 75% parallel. You might be wondering how can that be? The key is the Power Split Device. By electronically controlling where the power from ICE gets split(and how much) HSD can dynamically transform it's powertrain to take the most advantage of any situation. It is extremely flexible.
After you digest all those information, you can think why Prius still need electric drivetrain on the highway. And then think why Prius only need such a small (1.5kW) 99lbs battery.
Dennis
Nope. Diesel would not benefit much from disabling cylinder as it's combustion is already efficient. Pumping loss and other Otto cycle related problems had been minimized with Atkinson cycle and VCM.
Dennis
That explains it nicely.
I hope the engineer who invented that system got a big bonus!
I didn't think there'd be much gain, but it seems to work for Chrysler's 300.
If you just cut fuel you get extra oxygen in the exhaust which might overheat the catalytic converters. I believe that extra air is used to clean out the particulate traps on the new cars.
RE AUDI FSI Engines:
"sounds familiar" -- yes indeed! Sounds like a diesel engine modified to run on gasoline. Does it still need spark-plugs after it starts?
Brian
I didn't think there'd be much gain, but it seems to work for Chrysler's 300.
If you just cut fuel you get extra oxygen in the exhaust which might overheat the catalytic converters. I believe that extra air is used to clean out the particulate traps on the new cars.
RE AUDI FSI Engines:
"sounds familiar" -- yes indeed! Sounds like a diesel engine modified to run on gasoline. Does it still need spark-plugs after it starts?
Brian
I guess all the "CVT" talk is coming from marketing. As usual, their "dumbing down" of all things technical just creates confusion!
That's a really cool system! I'm sure the new Prius must be a quantum leap ahead of the first one in performance.
But I still don't totally agree with this:
" The only thing that diesel has over hybrid is lower fuel price in Europe."
Diesel still represents better utilization of resources (crude oil), can be synthesized easily (bio-diesel), and still makes more power per pound than gasoline. However, I'll bet the gas engine in the Prius (running at optimum speed) comes as close to diesel as you can get, reducing that gap considerably.
I'd like to see this HSD drivetrain with VW's 1.4-liter TDI from the 80+MPG LUPO replacing the gas engine. I'd expect 5% to 10% mileage gains over the gas Prius.
Of course, it won't match the Lupo, but that vehicle won't carry 5 adults in it either.
An interesting feature of the Lupo is that it has a fairly traditional 5-speed manual transmission but no clutch pedal. The transmission is shifted by a computer instead so it can pick ideal shift-points for optimum mileage.
The Lupo and Prius both indicate that regardless of fuel or drivetrain, electronics will play an important part of future drivetrain optimizations.
Brian
Hmmm--i can see that if there were a lot of hydrocarbons in the exhaust the extra o2 would make them hotter, but if the engine is properly lean it shouldn't. In fact it might make them too cool, if there's too much air blowing through them?
I know that with some gas engines, extra air is blown into the exhaust to allow hydrocarbon combustion. And with some turbo engines when boost is high, LOTS of gas is dumped into the mix to avoid detonation due to the heat/pressure. Neither of these ought to apply to diesel.
As for the FSI, the spark plus is still used, but when we want to run "lean" instead of throttling the intake, we spray just a little puff of fuel next to the spark plug. So the point is that the engine can be run with the throttle wide open reducing pumping losses. They also point out that you can create a layer of air insulating the charge from the cylinder walls, reducing leat loss. Clever stuff.
Sort of like diesel, except not quite as efficient, but we can rev to higher RPM's.
dave
http://www.thecarconnection.com/index.asp?article=7536&sid=17- 5&n=156
As far as I'm concerned, this puts the stake in the whole "deisal causes cancer" idea.
It is a fact that the oil industry has had too much control over this country for the last 100 years. Diesel can be made from coal or grain. Which we have a lot of.
ASTHMA is a rapidly growing problem, which is contributed heavily to by SMOG related emissions. In fact, that point is so well proven that the list of things to do to reduce asthma problems includes the recommendation move away from SMOG plagued areas.
So there is nothing for you to test. Just look up the EPA values with respect to SMOG emissions (NOx, HC, and PM).
JOHN
Vehicles contribute less than 24% of the smog in the major 25% U.S. cities (Dan Meszler). Add to that that many of the major smog contributing vehicles are old out-of-tune vehicles. A new diesel, particularly (pun intended) one running on biodisel or ULSD is going to pollute less than a gasoline engine of all but quite recent vintage. The reality is that any new diesel car is not going to negatively impact smog.
That doesn't account for the extra hydrocarbon emissions of gasoline vs diesel in storage, etc. Personally, i'd wager that the bulk of the hydrocarbons my car puts into the atmosphere is during the fueling process when i see vapors coming out of the tank, or some gasoline spills on the ground. I think my car smogged a 9ppm for hydrocarbons. Add spills and emissions at various stages of the extraction and shipping processes, and you've really got something.
No, i think trying to chase down that last few percentage points of emissions is a bit of a red herring. Moderns cars are already damn good. A 2 stroke lawn mower run for any period of time is going to pump more junk into the atmosphere than a well-tuned newer car. We'd be better off environmentaly pulling a old smoke belcher off the road instead of replacing 10 modern cars with hybrids. And, again, cars contribute to only 24% of the smog already.
That's why i think it's important to examine total lifecycle emissions, environmental impact, resource use, and energy consumption. That's where i still think diesel has the advantage. Longevity, lower manufacturing impact ( simpler, no special battery pack ) and a fuel with a lower environmental impact.
dave
That's interesting. There are fewer diesel cars today than during the 80s. Must be the hybrids causing the problem. Or maybe the pollen from growing more corn to make Ethanol. THERE is no proof that a modern diesel is causing those problems. You are ignoring facts and making up theories. You need to read the whole article. Is asthma increasing in Europe where they are moving toward 50% diesel cars?
And the official term is eCVT, isn’t it? Toyota’s website mentions that.
Yes, i do, but a lot of it is in print ( magazine ) sources.
But to start:
http://www.mindfully.org/Air/Lawnmower-Exhaust.htm
(this is for european 4-strokes, not the much worse 2 strokes you get here)
http://www.findarticles.com/p/articles/mi_m3165/is_1999_Nov/ai_57- - 165220
http://www.motorists.com/ericpeters/archive/wastedtime.html ( 24% of smog from vehicles )
"NRC estimates that 10 percent of the cars are producing 50 percent of the harmful exhaust emissions that lead to smog and ground level ozone. This has been confirmed by other tests and surveys over the years as well."
There's a lot more, but i'd have to go home and link magazine articles for most of the sources i know.
Consider too: as i mentioned my 6 year old car with the the 2.8: i-6 smogged at under 10PPM for hydrocarbons. I also average ~27mpg ( lots of highway ) and put on ~12KMPY. I crunched out that this means the tailpipe put out about .05 liters of hydrocarbons over the course of last year. I'm sure that more than that has been emitted in spills, tank vapors, etc. And consider gasoline being used as a solvent/cleaning agent, as is often done.
I can see a coal-burning powerplant from my office window. Nice big plume of smoke.
No, i think that as long as cars are fairly modern and in tune, pollution differences are marginal in difference. Resource consumption is the real concern--oil to be extracted from the ground, metals mined, etc.
I think this emissions is the focus, becuase it's easier to improve emissions and sell new cars this way than to get people thinking about the used resources. That might get them to scrupulously maintain their old cars which is probaly better, all told, than letting it going to pot and buying a whizz-bang new "clean" car.
dave
And this leads us back to the general difference in culture as well. According to the second article (I ignored the first since lawn mower emissions could be discussed separately), Europeans don’t care about emissions that contribute towards smog formations as much as they do against green house emissions. Still, wouldn’t it be logical to put this in a perspective? Does a clean gasoline engine (say, 100 HP) produce more green house emissions than a comparable diesel engine? And we could go beyond vehicular emissions to everything else if we had the data, but comparable to make sense.
UK market Civic... emissions:
Hybrid
CO2 Emissions (g/km): 116
Diesel
CO2 Emissions (g/km): 134
Based on this, it appears that hybrid is not only better in emissions contributing towards smog, but also beats a comparable diesel engine in terms of green house emissions (at least the measure that is readily available at this time).
A manufacturer's label does not make it official.
Use the engineer terminology instead. It has no loyalty to brand and doesn't make any profit from marketing. That term is: PLANETARY-CVT
JOHN
Sorry, but even a 0.00001% percent increase is a problem. Multiply that times the 60,000,000 new vehicles sold worldwide each year and the number becomes a reality with a lot of people suffering from breathing-related problems.
Just because one polluting source contributes less than another is not a reason for exemption. Every little bit really does make a difference... especially when the population is growing rapidly and driving time continues to increase.
> i'd wager that the bulk of the hydrocarbons my car puts into the atmosphere is during the fueling process when i see vapors coming out of the tank
Fortunately, my Prius doesn't. It has a bladder in the tank that significantly reduces evaporative emissions.
> Moderns cars are already damn good.
Again, amplified times 60,000,000 negates that claim.
JOHN
I assume you didn't come up with the "Planetary CVT" term, did you?
I quoted what Toyota mentions as the transmission in Prius. Is that wrong?
Did you realize that the parts that are replacing the traditional transmission are also required fundamental parts of a full hybrid? Without those parts, HSD wouldn't be a hybrid drivetrain. ECVT is a by-product of Synergy effect of the two drivetrains.
Synergy: The interaction of two or more agents or forces so that their combined effect is greater than the sum of their individual effects.
Dennis
How? SMOG is evidence that the pollution levels are already above tolerance.
Face it, the rural areas won't be able to take the ever-growing load after awhile either.
JOHN
http://www.detnews.com/2004/editorial/0409/20/a06-278229.htm
“Face it. Toyota eliminated the transmission, a true overall cost saving strategy... as well as being a way of reducing vehicle complexity & maintenance”
Dennis
That argument is absolutely absurd. If there's a .000001% increase there's going to be a .00001% increase in smog. Multiplying by the total vehicles produced gives you come constant figure across the whole planet.
This also leads to consideration of the manufacturing impact, as long as you're considering the whole planet's emissions. Diesel wins on this count: simpler systems, longer lasting, less to replace.
"Fortunately, my Prius doesn't. It has a bladder in the tank that significantly reduces evaporative emissions."
When you fill the tank, there is going to be some air displaced, the same goes for the gas station tank, shipping, etc.
Frankly, your arguments seem geared toward defending the prius, not the environment.
dave
Let's say an electric car can come to a stop with regen braking, without any brake pads being installed. What kind of brake does that electric car has? eBrake? You can say, since eBrake is a type of brake, then this electric car must have a brake.
But an electric car only has a electric motor that can also act as a generator to stop itself. It does not have a traditional brakes. The best thing is to stay away from traditional "labels" and dwell on it. This is exactly what is happening with eCVT argument.
Dennis
That perception doesn't change reality.
To be certified as PZEV, the vehicle must significantly reduce evaporative emissions. To do this, the automakers have been placing bladders in the tanks.
I use Prius as the example all the time because everyone jumps all over me when I sight yet-to-be released HSD vehicles or speak in general about HSD itself... Damned if you. Damed if you don't.
JOHN
You have shown absolutely no data to substantiate your claim. If asthma is increasing in Minnesota, better look at the ethanol. That is why CA is fighting to keep that horrid stuff out of our gas. It may be more of a health hazard than diesel. And not near as safe to handle. Furthermore the decreased mileage you get with 10% -15% ethanol negates any advantage it has as far as helping us reduce foreign oil consumption. Face it diesel IS the answer for cutting back on foreign oil and bio-diesel may be able to cut it even further. Show us some legitimate tests on modern diesel car engines that substantiate your claims & assumptions.
I don't need to. The data is so absolutely overwhelming you can find it everywhere.
Just ten seconds of searching on Google revealed this...
http://www.aafa.org
More than 60 million people in America have asthma or allergies, costing the U.S. economy over $20 billion each year in hospitalizations, medical services, lost productivity at work or school, and more.
When you read about the contributing factors, you'll see that smog is listed. And we all know there is an absolutely overwhelming amount of data documenting the variety of problems smog causes... including breathing related problems, and the reduction/elimination of federal road-improvement funding.
JOHN
That data shows exactly the opposite.
NOx emission increase with Biodiesel, not decrease.
B100 is even dirtier than diesel. It's less efficient and more expensive too. And it is worthless in the winter. Only B20 can be used, and even then it requires an additive which will add to the cost.
JOHN
Maybe overwhelming to you. Not to a scientific mind that wants facts. I think 59.99 million of those people are victims of tobacco smoke. I can tell you for a fact I breath better in Los Angeles today than in 1957 when we moved from there to San Diego. I say those asthma & allergy victims are barking up the wrong tree by chasing auto emissions.
As usual you did not address the issue. The issue is "tests on modern diesel car engines". Find that overwhelming evidence, not some vague website that has an agenda, and no substantiating evidence pertaining to modern diesel car engines.
Again more rhetoric with no substantiation. You forget that over half the people live where it rarely hits 20 degrees. And it is easy to add petroleum based diesel to compensate. It is the closest thing we currently have to a 100% renewable source of energy.
For asthma, yes.
There's no evidence that modern diesels will contribute to smog more than a modern gas car, including hybrids.
Yes, we all know the NoX is a bit higher, but as we already know cars are already only 24% of smog sources, and the bulk of those are older problem cars.
dave
That is where I am at in this research. Nothing shown here is even close to conclusive that diesel is as bad as gasoline at causing smog. If you are real concerned as I am you can find BP ECD-1 diesel in most civilized communities in this country. It is either less than 15 or 30 PPM sulfur. That all but eliminates the NoX that is always thrown in the face of people that are educated enough to know that diesel is a better way to save oil than any current gas powered vehicle.
We had more particulate matter in the air here in So. California during the big fires than all the cars in this state produce in a hundred years. Where were the greenies then. It was their fault the fires happened. They stopped the forest service from clearing thousands of acres of trees that were dead from a beetle infestation. Several people including my brother, have come down with asthma type symptoms since that fire. And we have the toughest regulations in the country. Don't get me started.
Dave,
You noticed when I asked for solid evidence that modern diesel engines were a problem, certain folks hid in the barn. They are good at dishing out misinformation, short on scientific evidence.