Gen 1 GM Volt Plug-In Hybrid (2011-2015)

[cwerdna]

^^^
The diagram and your statement leaves out the addition of 3 clutches that aren't present in Toyota's PSD.

The video at http://www.youtube.com/watch?v=d9-9atMw6Zs" onclick="window.open(this.href);return false; is a bit better than the 3 at http://www.plugincars.com/exclusive-video-want-know-exactly-how-chevy-volt-powertrain-works-95344.html" onclick="window.open(this.href);return false;.

 

[Volusiano]

^^^
The diagram and your statement leaves out the addition of 3 clutches that aren't present in Toyota's PSD.

True, the 3 clutches on the Volt's power train does make it more complex than the Prius's PSD. But I'm not sure if it makes it MUCH more complex, however. It basically uses the same planetary gear concept with a few "twists".

These twists (3 clutches) allow the Volt to gain advantages, like the ability to operate in series mode, and the ability to be in 2-motor mode for better efficiency at highway speed, etc. So these are worthwhile twists in my opinion that justify the added complexity.

 

[cwerdna]

^^^
While it does give it some advantages and the Plug-in Prius has limitations (e.g. can't go above 62 mph in EV mode (I believe due to MG RPM limitations), hard acceleration == ICE turning on), the Volt's CS mileage (when using "required" premium) is far worse than the regular Prius or PiP: http://www.fueleconomy.gov/feg/Find.do?action=sbs&id=32655&id=33324&id=33335" onclick="window.open(this.href);return false;.

 

[Volusiano]

^^^
While it does give it some advantages and the Plug-in Prius has limitations (e.g. can't go above 62 mph in EV mode (I believe due to MG RPM limitations), hard acceleration == ICE turning on), the Volt's CS mileage (when using "required" premium) is far worse than the regular Prius or PiP: http://www.fueleconomy.gov/feg/Find.do?action=sbs&id=32655&id=33324&id=33335" onclick="window.open(this.href);return false;.

Of course the Volt's CS mileage can't beat the Prius's CS mileage simply because the Volt is heavier due to its extended battery which gives the Volt the 40 EV miles. It's a trade-off that Volt owners would gladly accept for the ability to use the EV mode most of the times and the CS mode some of the time.

I don't want to get sucked into another debate between the Volt vs Prius. That's been done ad-nauseam already. I just wanted to add my opinion that the Volt's transmission is not that MUCH more complex than the Prius because they both are built on the planetary gear system. I'll admit that it's a little more complex due to the 3 clutches, but for good reasons as I already pointed out.

 

[cwerdna]

It's not apple to apple to compare the Volt's CS mileage vs the Prius's CS mileage simply because the Volt is heavier due to its extended battery which gives the Volt the 40 EV miles. Of course extra battery weight is going to be a trade-off on the mileage,

I doubt the weight of the pack is the only reason. From what I can find, the Volt's pack weight is 435 lbs. For the '12+ PiP (from Toyota's ERG), its pack weight is 168 lbs.

From Toyota's ERG, the PiP's curb weight is 3,186 lbs. http://avt.inel.gov/pdf/EREV/fact2013chevroletvolt.pdf" onclick="window.open(this.href);return false; mentions the design curb weight of the Volt is 3,781 lbs.

Some of the extra bloat (not limited to the Volt) can be blamed on Bob Lutz: http://www.thetruthaboutcars.com/2011/09/bob-lutz-ill-take-the-blame-for-gms-weight-problem/" onclick="window.open(this.href);return false;.

 

[LKK]

The Volt's transmission may be more or less complex than the Prius, but it is a lot simpler than the average automatic transmission, and cheaper as well. In an interview with Bob Lutz, ex GM VP, he intimated that the Volt electric drive system costs less than an automatic transmission.

While the Volt's drive mechanism is simple I think it's operation may be quite complex as the Volt seems to require an unusually large amount of software.

 

[DaveinOlyWA]

dont know if this has been posted already but a great illustration of the Volt power train

https://www.youtube.com/watch?v=AX5ZwzNwTc4" onclick="window.open(this.href);return false;

 

[GRA]

It's not apple to apple to compare the Volt's CS mileage vs the Prius's CS mileage simply because the Volt is heavier due to its extended battery which gives the Volt the 40 EV miles. Of course extra battery weight is going to be a trade-off on the mileage,

I doubt the weight of the pack is the only reason. From what I can find, the Volt's pack weight is 435 lbs. For the '12+ PiP (from Toyota's ERG), its pack weight is 168 lbs.

From Toyota's ERG, the PiP's curb weight is 3,186 lbs. http://avt.inel.gov/pdf/EREV/fact2013chevroletvolt.pdf" onclick="window.open(this.href);return false; mentions the design curb weight of the Volt is 3,781 lbs.

Some of the extra bloat (not limited to the Volt) can be blamed on Bob Lutz: http://www.thetruthaboutcars.com/2011/09/bob-lutz-ill-take-the-blame-for-gms-weight-problem/" onclick="window.open(this.href);return false;.

I suspect the primary reason for the Volt's lower CS mpg is the fact that they used an off-the-shelf Otto-cycle engine due to time and money constraints; the 2nd gen will use an Atkinson-cycle engine specifically to boost the CS mpg.

 

[DaveEV]

I suspect the primary reason for the Volt's lower CS mpg is the fact that they used an off-the-shelf Otto-cycle engine due to time and money constraints; the 2nd gen will use an Atkinson-cycle engine specifically to boost the CS mpg.

I suspect that makes a smaller difference in this application than one might think - GM has stated before that the throttle is basically wide open all the time when the engine is running which eliminates the benefit of an Atkinson-cycle engine (pumping losses due to having to suck air past a nearly closed throttle.

 

[MTNRanger]

I suspect that makes a smaller difference in this application than one might think - GM has stated before that the throttle is basically wide open all the time when the engine is running which eliminates the benefit of an Atkinson-cycle engine (pumping losses due to having to suck air past a nearly closed throttle.

The Volt only does full throttle (even then it may not be full throttle) when in mountain mode with a very low SOC. Otherwise, the Volt has been tuned for NVH. There is a quote from a Volt engineer that states that NVH took precedence over MPG. If the Volt was optimized for full throttle, the MPG may have been closer to 45-50 than 40 HWY.

 

[DaveEV]

The Volt only does full throttle (even then it may not be full throttle) when in mountain mode with a very low SOC. Otherwise, the Volt has been tuned for NVH. There is a quote from a Volt engineer that states that NVH took precedence over MPG. If the Volt was optimized for full throttle, the MPG may have been closer to 45-50 than 40 HWY.

There is a difference between full throttle and full power. You can have WOT with low RPMs if you put enough load on the engine. Just look at what happens if you floor a regular car in say 3rd gear from 20 mph. You may have a wide open throttle at 20 mph, but you sure aren't getting full power.

See this thread on gm-volt.com for more background:
Wide Open Throttle Questions

This referenced video is informative, too, forward to 4:30 to hear the statement about WOT:
[youtube]http://www.youtube.com/watch?v=an-VyIau-FM[/youtube]

 

[GRA]

I suspect the primary reason for the Volt's lower CS mpg is the fact that they used an off-the-shelf Otto-cycle engine due to time and money constraints; the 2nd gen will use an Atkinson-cycle engine specifically to boost the CS mpg.

I suspect that makes a smaller difference in this application than one might think - GM has stated before that the throttle is basically wide open all the time when the engine is running which eliminates the benefit of an Atkinson-cycle engine (pumping losses due to having to suck air past a nearly closed throttle.

They're certainly shooting for better mpg in gen 2, and are going to use an Atkinson cycle engine; While I'd like to see 45 mpg highway, I think 42 or 43 would probably do it. Barring a huge decrease in weight due to extensive and expensive use of Al or CFRP or better batteries, I don't see how they could gain that much through reduced powertrain losses alone, so I think it will have to be through engine tech - Atkinson cycle, direct injection etc.

 

[IBELEAF]

Anyone knows if it's possible to to extend lease on Volt?

 

[DNAinaGoodWay]

January sales thread seems delayed, but according to insideEVs, volt sold 918.

 

[MTNRanger]

Dealership availability seems very low. I checked my closest eleven dealers and there are only 13 in stock. One of the dealers used to stock at least 6 by itself.

 

[LTLFTcomposite]

http://autos.yahoo.com/news/gm-releases-first-details-next-gen-ecotec-engine-143005749.html" onclick="window.open(this.href);return false;

One of the units, most likely the 1.0-liter three-cylinder version, is expected to be utilized for the redesigned 2016 Chevrolet Volt.

Promising... smaller engine, bigger battery? maybe?

 

[pkulak]

http://autos.yahoo.com/news/gm-releases-first-details-next-gen-ecotec-engine-143005749.html

One of the units, most likely the 1.0-liter three-cylinder version, is expected to be utilized for the redesigned 2016 Chevrolet Volt.

Promising... smaller engine, bigger battery? maybe?

That would be nice. That car is way too much engine.

 

[Volusiano]

http://autos.yahoo.com/news/gm-releases-first-details-next-gen-ecotec-engine-143005749.html

One of the units, most likely the 1.0-liter three-cylinder version, is expected to be utilized for the redesigned 2016 Chevrolet Volt.

Promising... smaller engine, bigger battery? maybe?

That would be nice. That car is way too much engine.

Here's an article where GM's Pam Fletcher explained why they went with the bigger engine in the first place. Below is the excerpt:

"ABG: Why do your EREVs need four-cylinder power to extend their range when BMW's i3 makes do with an optional 650 cc two-banger?

PF: I get that question all the time: why not something smaller? You don't really need that much. You use the electric to its ability, then you just need to limp. But we designed those cars to go anywhere, any time, and we don't want their performance to be compromised. If you're driving through the mountains, we don't want you to be crawling up grades, or to be limited on any terrain. So it's optimized to be able to travel literally the biggest grades and mountain roads around the globe at posted speeds. Because what if you can't?

Another good reason: when the engine is on, you have to run it wide open throttle, max speed, most of the time. And while we can do a lot with acoustics, and the ELR has active noise cancelation, a small-displacement, low cylinder-count engine at high speed, high load all the time isn't something you want to live with. That's how we came up with the balance we did among the key factors of performance, NVH [noise, vibration and harshness] and range."

 

[pkulak]

Yeah, so they didn't compromise anything... except cost, interrior room and electric range. From reviews I've read, the i3 generator is not loud at all. BMW got it right.

 

[LKK]

My guess is the next Volt will not have a 3-cylinder engine. The normally aspirated three puts out only 75 HP, not enough to power the 55 KW (75 HP) generator because the ICE will have to be operated at max power. The turbo 3-cylinder is rated at 125 HP, enough to power the current generator but adding a turbo, inter cooler and other bits is probably more expensive than a simple normally aspirated 4-cylinder.

If GM wants to get the advantage of an Atkinson cycle, the effective displacement of the ICE is cut by about 15%, another reason against the 3-cyclinder. This eliminates the normally aspirated variant as its output power drops below 70 HP and the current generator needs around 80 HP. I'm not sure you can run a turbo engine on an Atkinson cycle. If you could the effective power drops to around 110 HP, but this means you have to run this engine pretty hard.

My guess is the next ICE will be a 4-cylinder, direct injected, variable valve timing, Atkinson cycle inline four with displacement similar to the Prius or Ford hybrid engines.

In regards to the BMW I3 range extender, Pamala Fletcher is right. It does not produce suffient power to operate a generator capable of meeting the average power demands of the car. European reviews of the I3 speak of max speeds of around 45 MPH on the level when the battery is fully depleated. Performance on hills is seriously degraded from level performance because there isn't a sufficient state of charge maintained in the battery to support a buffer for extra power when you need it. The I3 is a great battery EV but it's range extender capabilities fall well short of the Volt which provides full performance while on the battery or the range extender.