New Volvo PlugIn planned

wow!! now that sounds cool. no prices or availability here announced.... ya, Europe with $9 gas gets all the good stuff. gas too cheap around here still. CMON $6 a gallon!!

 

wow

 

have a volvo v50 we picked up in Sweden last year on their overseas delivery program. a plug in might be my next purchase, especially if I can get another free trip to europe.

 

I'm not an engineer or physicist, just college physics. However, from a basic physics point of view, it seems that a series hybrid would thermodynamically seem less efficient. Of course both the series and parallel hybrids would be equal in recapturing the energy by converting kinetic energy to battery electrical energy during idling slowdown or during breaking. However, when you use an ICE to charge up a battery to THEN drive a motor train there would be less efficieny in this multi step process than just using an ICE to drive the motor train in the first place.

Am I just being a toyota hybrid homer? Is there something in the series hybrid I'm missing?

I think the newcomers are using this as a gimmick to be different from toyota They can market this as a differentiating feature from toyota even though it may not be a superior feature. But the public at large won't know any better except for what's broad casted on commercials. Kind of like "Our truck is better cause it has a Hemi!" Then most of the purchasing truck customers nod with a blank stare as if they understand.

 

Converting from one type of power to another is less efficient, BUT perhaps the ICE vehicles that we drive today are Very inefficient to start with. Perhaps, harnessing the torque and power of an ICE at idle rpm can turn ten generators (or one huge generator) that generates a lot of electricity. If the engine is idling, it can run for a LONG time, and meanwhile A LOT of electricity is being generated. Sure, according to thermodynamics, the fuel would have to contain more Joules than the electricity generated, but if the conventional ICE is "extremely inefficient," then this new system might be simply be "inefficient," and thus more efficient, and producing more mpg. Perhaps a diesel could turn a MASSIVE generator at idle rpm.

As for the series versus parallel hybrid's regenerative abilities, I agree with you that it seems it should be the same. The variable is how big the generator is. Volvo is claiming this [Re]generator is 300V at each wheel, and that conventional disk brakes are simply not needed. However, where the series and parallel show clear differences is how the gasoline is turned into mechanical energy. (which I explained my hypothesis in the above paragraph)

 

"And because electric motors become generators when turned in reverse, Volvo's completed car will have no disc brakes (or wasted energy from braking friction). With wheel motors, close to 100 percent of the energy from slowing the ReCharge is returned to the battery."

"The car can do 0-60 mph in about nine seconds, with a top speed of 100 mph. On a three-hour charge it will go roughly 60 miles."

"When the four-cylinder flex-fuel motor kicks in to recharge the battery, efficiency will step into the 40-mpg range." (consistent with GM Volt's comments)

AWESOME !!!!

 

There will have to be a mechanical parking brake. I don't see how you could get by - get the car built - without one.

Also, if the electrical load isn't high enough and the batteries are fully charged and you are braking, that regen energy will have to go somewhere (like a resistive element). So, energy can and will be lost (besides conversion losses from the wheel motors and DC/DC converters between the HV bus and the battery pack).

 

Interesting, but perhaps we should coin another acronym.

NACC is my proposal, for Not Another Concept Car. :Cry:

Another concept car.

Let me know when I can buy it.

 

Okay. This explanation is acceptable to me.

However, if the ICE kinetic driver is SO inefficient(which it probably is), then wouldn't efforts to make an efficient ICE battery generator be better spent in making an efficient ICE kinetic driver. Also, you could just address the idling wastes by just doing what toyota did and turn the ICE off when not in use.

The advantage I see here is if the capacity of the battery were large enough, that it would capture all the energy from gas without ever wasting any of it via idling or braking. But the parallel hybrid, with current technologies, could also achieve this by just adopting a high capacity battery also.

Like I said, I think series hybrids builders(specifically GM) are doing this just so they will be able say that they are different. Then they will eventually process this difference in their misinformation marketing machine to sway the public in their favor.

But unless this series technology translates to better fuel efficiency at a lower cost(which I'll bet a thousand dollars that they won't be able to achieve), I don't think the public is going to buy it.

 

There will be brakes on the car (for all the reasons you mentioned). Volvo is just a bit behind Toyota on the learning curve. The block-headedly stubborn engineers at Volvo haven't quite gotten their heads around all of the 'realities' yet. These are the same bone-heads that refused to provide a hard-wired (not even an interface point for aftermarket solutions) iPod interface to the stereo systems in their cars until the 2008 model year. They still don't offer an integrated Bluetooth telephony interface (too 'forward-thinking' for them)....

 

Series hybrids have two advantages;

1. [FONT=&quot][/FONT]Simplicity: With a series hybrid an electric motor drives the wheels and the ICE generator has no mechanical connection to the wheels. This eliminates a complicated and expensive component, the transmission. (The Prius has all the components of a series hybrid (MG1 / MG2) + a transaxle
2. Steady State Operation: In a series hybrid the ICE only has to run at one speed. This allows the manufacturer to optimize valve timing for maximum efficiency. A Parallel hybrid has the same limitations as a conventional engine in that it has to run at a wide range of RPMs. The opening and closing of the valves are controlled by a camshaft. A camshaft can only be optimized one RPM. In an engine that operates over a range of RPMs the camshaft is a compromise that best fits that range of RPM. There have been advancements with variable valve timing but at best this gives a couple of effective cam profiles. The ideal solution is to have the valves open and close with an electric solenoid that could have infinite variation. This has been tried in the lab but has not made it to production use yet.

The Prius uses parallel hybrid technology because Toyota is limited in how much NiMH battery capacity they are allowed to use. The small battery in Prius doesn’t have enough capacity to provide the spikes of power needed in a series hybrid.

An ICE (Internal Combustion Engine) is a heat engine. It is thermodynamically limited to a maximum theoretical efficiency of 37% using metal parts. Electric motors are typically 95% efficient and can theoretically 100% efficient.

 

Yes. but if you're using a ICE to power the battery then the maximum efficiency(even theoretically) is 100% x theoretical efficiency of the ICE.

But the rest of the explanation is also very informational thanks.

 

Good point!

The railroads of America have used diesel-electric series engines for the past several decades. Originally, I thought this had to do with torque and not breaking the ICE if the train wouldn't move as fast as the ICE wanted it to. But after learning that this Volvo and the Chevy Volt get better mpg with a series hybrid than a convetional ICE, I am starting to wonder if the railroads didn't already know this the whole time. Can anyone offer more insight on this?

 

Here's what you're missing:

ICEs are extremely inefficient at best, but they are outrageously inefficient when operating well outside their ideal parameters, and even worse when they must be capable of delivering a great deal more power than the amount required most of the time.

In a conventional car, the ICE must be capable of accelerating the car from a stop, which requires a lot more power than steady-state driving. A hybrid can have a low-torque (more efficient!) ICE because the electric motor can supply torque when needed, and a much smaller ICE because the electric motor can supply power during the brief moments it's required. Thus the ICE is better matched to the load. It's hard to emphasize sufficiently how much efficiency is gained by this strategy. But it still only goes part way, and is short of the maximum theoretical efficiency.

Regen braking and shutting off the ICE at stops account for very little of the Prius's exceptional FE. Most is achieved by having an ICE more nearly matched to the load the car needs most of the time.

But a series hybrid only runs the ICE at exactly the rpm and exactly the load it was precisely designed for. Then, if you use wheel motors you eliminate drive-train losses.

The Volvo article is only claiming 40 mpg after the ICE starts up, so the Prius ends up with better FE. But series hybrid has some real advantages, and IMO is better suited to a PHEV, where most daily driving will be done without the ICE at all, and the ICE is only used for road trips. Of course, I think 75 miles is the minimum for a PHEV. A 40-mile plug-in range might get me to buy it, but I'd pay a premium for a 100-mile range, and then use the ICE only on those summer trips to Canada, or if I forget to plug it in.

 

Let me cite this example and see if this is correct. When an ICE is used to attain a car speed from 0-15 mph one time, it's very inefficient. The same amount of energy can be captured/stored by a battery and with that stored energy the car can attain the 0-15 mph maybe 1.25 or 1.5 times with an electrical motor(but maybe not as great of acceleration)?

Or how about this metaphor? Using an ICE would be like watering a small plant with a big bucket. It's difficult to do so without wasting a lot of splashed water. But if you poor the bucket of water first into a cannister with a small hose attached to it, you could much more efficiently feed the small plant many more times than if you were just using a big bucket?

 

What's this "parallel" technology you speak of?

Since IMA and BAS have almost nothing in common with HSD and Ford's hybrid system, calling them the same causes confusion.

The proper term is "series-parallel" for hybrids like Prius. But most call it a "full" hybrid since it offers wider range of operational modes than the other.

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As to your question of efficiency. In a series hybrid the total efficiency (E) would be:

E Ice x E generator x E inverter x E battery x E controller x E motor

That does seem very complicated but it allows each component to be selected for maximum efficiency. The series layout also allows almost infinite variations of packaging because there is no mechanical connection between the engine and wheels. It is very easy to run a wire from a battery to an electric motor. It is very difficult to connect an engine to wheels using gears, shafts, belts, chains, etc.

You are also assuming that a mechanical system is 100% efficient. This is not the case. The general rule of thumb is that a 2wd drivetrain is 85% efficient and a AWD drivetrain is 75% efficient.

As mentioned above, the Prius is a Series-Parallel hybrid. It can be run in series, parallel or a combination of both due to the power-split device. I don't see this as an advantage but instead a liability. Yes, it is brilliantly designed but it is a complicated solution to a simple problem. I believe that the reason Toyota went with this solution is because they were not allowed to use a large enough NiMH battery for a simple series hybrid. The series-parallel system in the Prius has all the expense and inefficiencies of both systems.

 

The railroads used very large, lightweight, Diesel Engines due to their very high reliability and efficiency. The rub is giant diesels run at one rpm ideally. The electric conversion was the best way to convert this single rpm diesel output into the varying speed for the locomotive. The same is true of many modern ships. Most cruise ships have diesels operating in the same manner....and the Prius made good use of the same concept.

 

No. You are still missing the point. Note that an ICE does not run at the same efficiency all the time. It reaches its best efficiency when operating at exactly its design rpm and at exactly its design power output.

But in a conventional car, it must be capable of accelerating the car from 0 to 60 (high output over variable rpms) at some relatively short time.

Here's the point to note: The engine that is capable of that high-power delivery, for hard acceleration, becomes extremely inefficient the rest of the time. If you get 37% efficiency 1% of the time (during hard acceleration) and 5% efficiency 99% of the time (while cruising) your average overall efficiency is not much better than 5%.

I don't actually know the efficiency of those big ICEs when they are delivering low power, and I know that modern engines have improved a lot.

But a series hybrid can operate its ICE always at exactly its peak efficiency because it always runs at exactly its design rpm and its design power output. If that power is more than needed to push the car, it goes into the battery, and when the battery is full the ICE shuts off for a while.

In a car that gets all its energy from gasoline and cannot store very much electric energy due to the capacity of its battery, Toyota's HSD is probably the best solution today's technology allows. It is my opinion that in a car that operates entirely on grid power most days, and only uses the ICE for road trips, series hybrid with wheel motors is a superior idea. You eliminate the drive train and the differential, you simplify traction control and stability control (no more loss of power on hills because each wheel can be made to turn at the desired speed, and adequate traction at any one wheel is adequate to move the car) and for all those short trips where gas is not needed the ICE can be left entirely out of the equation. The biggest problem will be keeping it operational and reliable when it's only run once a year.

Again, a car that's usually run as an EV is better off separating the ICE completely from the drive train. A car that's always run on gas is better if much of the engine's power can be delivered directly to the wheels without conversion. Prius does this admirably. But Prius is a gasoline car. And IMO we need to look beyond gasoline.