Discussion in 'Chevrolet Volt' started by adrianblack, Oct 11, 2010.
Brisk is how I accelerate, specifically a quick hit up to 3500 RPM.
What are you implying?
I agree with most of your understanding. To connect in EV or in series mode the clutches should engage at 0 rpm and there should be minimal wear. The modes between power split or output split and serial are a little unknown to me, and my understanding is slightly different than yours.
First what we know is the threshold of shifting from power split to output split is between 30-70 mph. There are two threshold speeds lets call them T1 and T2 that are set by the software depending on load on the motor.
If we are bellow T1 and we need power we would go from 1 Motor Mode to series mode, and would not dirrectly go to output split. So I would eliminate this mode
If we are above T1 and needed power we would go to this mode.
I do think you are making it too complicated MGa can momentarily stop, as MGb changes speed to maintain the requested throttle. MGb could not provide full acceleration, but I think software would wait until the car was not accelerating. Then C3 would engage at 0 speed. MGa would spin to start the engine, then once started software would go to the normal output split mode.
I think this may be what happens. MGa and the motor could be slowed to slow idle and low torque. C1 unclutches, C2 Clutches, This will provide little wear to C2, but there will be some. It might be severe enough for C2 to only last 300,000 miles. It may also be implemented in the manner of the sonata hybrid. C3 would release the engine, then stop and engage C2, then release C1. MGa and the ICE would then rev match and then engage C3. This provides minimal wear on all clutches.
Again, I am not sure what gm has actually implemented, but I don't think we need to stop and start the ICE. C3 can unclutch, then MGa can stop for clutching C1 and releasing C2. Then MGa can rev match and C3 engages.
Honestly, there were sarcasm brackets. I plainly stated that the average driver will accelerate fast enough to kick on the ice in a phv prius. If you have become a hyper miler and think the prius is brisk and 40 mph is as fast as we drive, I am clearly stating this is not how the avearge driver drives. Be proud of your slow careful driving. You are not normal you are a hyper miler.
So... are you in denial or just enjoy debating?
You know I accelerate faster than average and you know I have already driven a PHV.
Why does it matter? PHV Prius intelligently selects the most efficient combination and it is automatic. Does it bother you when Volt turn on the gas engine when the battery temp is low?
I think the guy from Inside Line summed it up pretty well:
While you can make a plug-in hybrid run on electricity all the way up to top speed, that may not be the most efficient strategy, especially if your gas engine is pushing 50 mpg on its own. In this instance, allowing the gas engine to help above 65 mph may yet be the most efficient use of both electricity and gasoline. The Volt actually does acknowledge this, but only after the battery runs down and it slips into "range extending" hybrid mode. If the gas engine did better than 31.1 mpg (or, per the label, 37 mpg), it might actually be more efficient to have it help mechanically drive the planetary at freeway speeds all the time.
In recent interview, Lyle Dennis asked:
In the next generation Volt would you consider having the mechanical supplementary connection be engaged during all extended range time?
It’s mechanically inefficient to do that. The only time we bring that on is when we can take advantage of a higher efficiency capability. It gets us five or ten percent efficiency for us to bring those clutches on. We will do whatever it takes to get the most efficient performance for the customer. We wouldn’t want to artificially hurt the customer going down the road from a fuel efficiency point of view. There’s no reason we can see with this architecture to do it any more than we are doing.
So it appears, Volt will not benefit from the blended charge depletion mode due to the inferior PSD setup.
Denial of what? You are being disingenuous going off into ridiculous land hence the sarcasm. Do you honestly want us to believe your reports or those of every one else. Do you think 40 is fast?
What is faster than average. I can't do it in my prius, how could you do it in the phv prius. The prius is the slowest accelerating car that I have driven in the united states. Do you think 0-60 in 30 seconds is fast. That is what has been reported if you stay in ev mode. I doubt 0-60 in ev is even under a minute with full ac on.
The phv prius is a blended hybrid. Stop your whining and volt hating and stick to the facts. I was being kind in my last comments. I see that doesn't work with you, since you just make up your own facts as you go along. OK happy now no sarcasm braces. Now act offended and whine about how unfair it is to call the phv prius a blended hybrid. But no matter how much you pretend and make up that is what it is. Now are you going to pout and say I'm calling you names?
Bother me, no. It just makes it different. If you want a pure ev mode the phv prius does not have it. I was just trying to state facts, but john seems to want to disagree and pretend it does have this ev mode as strong as the volts. I hope you don't have the same problem.
As I stated earlier, the phv prius doesn't necessarily intelligently chose the mode, it was chosen at design time. There is an acceleration limit dictated by the electronics. I think this is a legitimate area to discuss, since this is the topic of the thread. Is this design superior. IMHO a combined design is superior, where the battery and motor are powerful enough for pure ev mode, but the car allows the driver to choose blended mode. The volt does have this hardware but not the software. I am hoping that the Gen IV prius includes both the hardware and software.
It does not bother me that the engine turns on when its too cold. I believe this is also a design compromise for efficiency. I also live in a place where it might be too cold 2 days out of 5 years. For those in colder places it may be a different decision, and they may prefer a car that has a robust enough heater and battery to keep the motor off. Again, I think the software should allow the driver to choose.
Like you said, PHV Prius is different so why does it bother you when the gas engine turn on? Just focus on the results. Nobody is pretending PHV Prius' EV mode behaves like the Volt. You are the one claiming Volt's EV mode is superior. I am saying it is counter productive. Again, look at the results. PHV Prius' EV is good enough to cover those MPG killing short trips. It is the best use of electricity.
PHV Prius was intelligently designed and it operates intelligently. I'd say Gen3 Prius was designed with plugin in mind. Every components were sized and spec to do more with less. Just look at the Volt. It has 380hp total (MGs and ICE) but it only has 100 mph top speed.
That will add weight and cost a lot more. Volt's hardware will not allow efficient blending operation. See my previous post.
I never said any such thing.
I simply pointed out that the PHV has more electric-only power than the no-plug model.
You do indeed like to debate.
PHV Prius is a very bright solution as it is. If you want an EV mode, try not to floor it during the charge depletion range and there you have it, it runs EV when required (max throughput). After that, remains an hybrid, I would stick to the honour of being THE HYBRID, this is PC, why not?
Austingreen, if anything changed much in this project, it would be in order to simplify even further. Bear in mind you are an owner of the 3rd gen of a tremendous car, a real asset for Toyota and for the planet, you know it, deeply perfected over a good design on the start. And simplifying further, that would bring out a BEV, not a E-REV.
Thanks for your insight
I gathered some more info to help us figure some stuff out
MGb is 149hp with 273 ft-lb of torque
MGa is 74hp
Voltec ICE is 1.4 L Engine 80 hp
The above quotes are from MotorTrend via gm-volt.com
Motor Trend Explains the Voltâ€™s Powertrain
It seems MGa kicks in above 70 mph for efficiency reason. I assume this means MGb can take over load temporarily, albeit inefficiently, during mode transitions. This way, MGa can spin down, whenever necessary, to lock the ring gear, allowing clean clutch application.
The worst case scenario is the voltec powertrain reduces power for a few seconds to cleanly apply the C3 clutch during transition to output split mode. This probably isn't as noticeable as changing gears in a manual transmission, which results in no power to the wheels.
Exactly. I would expect that The pause would take well under a second and the car would be able to maintain speed but not accelerate as fast. The power that MGb can provide starts going down as the speed gets higher than about 43 mph but this is gradual as you can see by the graph. We don't know what happens over 70, but power would start dropping off more significantly. Once the car entered compound mode and the ICE is spinning there is even more horsepower at the drivers discretion to accelerate.
2011 Chevrolet Volt Engine Graphs - Motor Trend
Just to note the graphs should be scaled to hp/lb to do a fair comparision with the phv prius that is also graphed.
After the above article came out gm clarified that compound mode could transition as low as 30 mph.
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