Feb 24

Watching the Volt’s 4ET50 transmission shift gears in extended-range mode

 

By George Bower

Does anyone remember “double clutching?” I do. It was a method of shifting a crash box (i.e., non synchromesh) transmission to “synchronize” speeds before a downshift. For example, on a shift from 4th to 3rd gear you would shift from 4th to neutral, let out the clutch and raise engine speed in order to synchronize then push in the clutch and shift into 3rd. If you were really good at it there was no gear grinding and you could actually make the final shift without pushing in the clutch. There are 3 clutches in the 4ET50. In order to save wear and tear on the clutches, the Volt synchronizes the speeds of the input and output side of the clutch before engagement.


 
This synchronizing was captured by GM-Volt forum moderator WopOnTour (WOT) using the MDI data acquisition tool on an acceleration to 100 mph in Extended Range Mode found here. Each snapshot was then turned into a schematic so it is very easy to see what is going on. Not only do you see the clutches “synchronize” you also see the Volt shift from series mode to Power Split Mode … Pretty cool stuff and totally unique to the Volt.

In the first snapshot, the Volt is going 50 mph during a slow acceleration. The car is in series mode during extended range operation. It is obvious from the schematic. You can see that the ICE is coupled to the generator and totally unlinked from the wheels. This is the beloved series mode everyone dreams about as being a pure series EREV … The shift to power split occurs a few snapshots down from here.

First, WOT’s snapshot 1 taken w/ MDI (click on this and following images to enlarge):
 

 
Now the schematic:


 
In the next snapshot we are in transition to power split mode. Clutch3 opens and MGA speed drops to sync w/ ring gear which is at zero rpm (grounded).
 
First the MDI snapshot2:
 

 
And then the schematic 2:
 

 
In the next snapshot we are still in transition to power split mode. Clutch 2 closes to link MGA with ring gear which is still tied to ground at zero rpm.
 
MDI snapshot 3:


 
Schematic 3:
 

 
In the next snapshot 4, clutch 1 has opened, the ring gear is untied from ground and MGA and ring gear speed is increasing to synchronize with ICE speed.
 
MDI snapshot 4:
 

 
Schematic 4:
 

 
In snapshot 5, clutch 3 closes linking the ICE to MGA and the ring gear which is transmitting power directly to the wheels. Note however that MGA appears to be supplying the torque and power to the wheels (as opposed to the ICE).
 
MDI snapshot 5:
 

 
Schematic 5:
 

 
In the next MDI snapshot 6 taken at 70 mph, the transition to power split mode is complete. The ICE is supplying power directly to the wheels thru the ring gear. Note however that the torque into MGA from the ICE is higher than the torque out of MGA. This implies that MGA is supplying electricity out (Presumably to charge the battery).
 
Snapshot 6:
 

 
Schematic 6:
 

 
In the next snapshot 7, the Volt is going 80 MPH in power split mode. The ICE is supplying power to the wheels (with some power being taken off to charge the battery).
 
MDI snapshot 7:
 

 
Schematic 7:
 

 
In the final snapshot 8, The Volt is at 100 mph (wow!!), the ICE is supplying power to the wheels. Note however that the torque into MGA from the ICE is slightly lower than the torque out of MGA. This implies that power is being drawn from the battery to MGA and MGA is supplementing the ICE with additional power.
 
MDI snapshot 8:
 

 
Schematic 8:
 

 
Conclusion

The Volt is an amazing piece of engineering. There is not one other electric vehicle out their that can do what the Volt does. All the other EV’s are just “one speeders”. No other plug in hybrid allows one to drive all the way to 100 mph in all electric mode … That however is in EV mode which would be another slide show for another day!

Cheers, Volt heads!!

This entry was posted on Friday, February 24th, 2012 at 5:55 am and is filed under General. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.

COMMENTS: 55


  1. 1
    usaisgreat

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    Feb 24th, 2012 (7:01 am)

    Great job WopOnTour! This answers a lot of questions as to how the VOLT transitions in the Extended Range Mode. You did a nice job capturing the data and creating the schematics that show the mechanics behind it. The VOLT is really a simple machine when it comes to the drive system and this helps to show that well. Very well done!


  2. 2
    George S. Bower

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    Feb 24th, 2012 (7:05 am)

    Note that the numbers in red and brown are calculated numbers using the PG equation derived here:
    http://gm-volt.com/2011/12/09/solving-the-volt%E2%80%99s-extended-range-combined-mode-power-split/


  3. 3
    George S. Bower

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    Feb 24th, 2012 (7:10 am)

    usaisgreat:
    Great job WopOnTour! This answers a lot of questions as to how the VOLT transitions in the Extended Range Mode. You did a nice job capturing the data and creating the schematics

    Thx,

    WOT got the snapshots. I turned them into schematics. If you notice, the slip speeds are displayed in the snapshots and were used to get MGA and ring gear speeds.
    GSB


  4. 4
    Nelson

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    Feb 24th, 2012 (8:06 am)

    I love this kind of info. The one variable missing is ICE fuel consumption at each phase. That would answer my question. Is the Volts ICE more fuel efficient the faster the Volt goes? My guess is yes.

    NPNS!
    Volt#671


  5. 5
    Shaft

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    Feb 24th, 2012 (8:11 am)

    Terrific exposition! It must have taken quite an effort. Thanks for making it available.

    Is it possible to add the torque from MGB throughout the process?

    Do you think MGB is also supplying power at any point in snapshots 5-8?

    In snapshot 6 you say “presumably to charge the battery”. But is it also possible that the excess power is going straight to MGB?


  6. 6
    Jean-Charles Jacquemin

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    Feb 24th, 2012 (8:28 am)

    Thanks WOT and George,

    This is a post early readers of gm-volt.com appreciate. We had long discussions/debates on this and I concur with the questions about the fuel efficiency of the engine. If we get those last answers (sorry for the extra work, but will give a chance for WOT to go back to 100 mph with his Volt !), our happiness will be (almost) complete.

    JC NPNS


  7. 7
    ClarksonCote

     

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    Feb 24th, 2012 (8:53 am)

    Why negative RPM’s on the traction motor in the 100mph last picture? I guess I don’t understand what that number means, especially if the battery is also supplying some of the power at that point in addition to the ICE.

    join thE REVolution


  8. 8
    BoultVolt

     

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    Feb 24th, 2012 (9:32 am)

    Interesting stuff, though like ClarksonCote, I’m confused by the negative rpms for the traction motor in schematic 6-8 given the statement that MGA is “generating” electricity.

    Is that because the SOC might be low and hence it need to generate power to old MGB but is not providing quite enough power? Or is there is odd energy balance withere the power needed to hold it would not be worth the added efficiency gain from hold it still. Or is there just something wonky in the torque computations?


  9. 9
    DonC

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    Feb 24th, 2012 (9:42 am)

    Thanks George and WOT! Nice stuff. Lots of technical details but the big deal is that the sync happens before the clutches engage so we owners won’t experience premature clutch failures.

    I was under the impression that above roughly 70 MPH MGA and MGB worked together to drive the wheels but this suggests that only MGA is powering the wheels. Is that right or am I missing something?


  10. 10
    Bob D.

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    Feb 24th, 2012 (10:03 am)

    As an amateur race driver I always loves me some tasty data ack.

    And this stuff is extraordinary. Nice work! It makes this phase of the genius behind the Volt drivetrain come to life. I can’t wait to see what data you can scrape off the Volt when driving up to 100 MPH in all EV mode.

    Thanks so much for sharing your wonderful work on this with all of us.

    And, yes, I’m curious too about the meaning of the negative torque numbers on the B-motor.


  11. 11
    JImB

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    Feb 24th, 2012 (10:38 am)

    I don’t really understand this article but want to add “the Prius does it better”.

    Sorry, couldn’t resist. Now the Prius Trolls don’t have to bother typing that for themselves today.


  12. 12
    Loboc

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    Feb 24th, 2012 (10:58 am)

    That last diagram (100mph) is interesting. It shows that all three tq sources *could* be simultaneously engaged from 0mph yielding 500+nm (!).

    The ICE would have to be on it’s torque curve to do this, but, since you can go negative rpms with MGB, you can go positive with the ICE for launch.

    This makes Corvette’s launch control seem primitive.


  13. 13
    DonC

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    Feb 24th, 2012 (11:37 am)

    Loboc: That last diagram (100mph) is interesting. It shows that all three tq sources *could* be simultaneously engaged from 0mph yielding 500+nm (!).

    Not getting the three sources. There are only two sources — the engine and the battery — and only two connections to the wheels — MGA and MGB.

    In practice the Volt hesitates before delivering available power to the wheels. Same for the Leaf. Not sure if this is to protect the battery or the axle or what. The point is that the theoretical amount of torque available at 0 MPH is already much higher than what you get in practice.

    Having said that, the Volt is very quick in practice. Before the Volt in an Acura which supposedly is faster, when I came up to a line of cars with four or five in the right lane and no one in the left lane, if I wanted to go right at the next light I’d get in the right lane. With the Volt I’ll always get into the left lane because I know I’ll beat the first vehicle in line by 30 or 40 meters. Even if the first vehicle guns it, which has never happened, I know I’ll be able to get behind them because the second car won’t be able to keep up. In doing this I don’t look like a jerk because there is no muss, no fuss, and no noise, and I never get in any other car’s way.

    Electrics just have different drive characteristics.


  14. 14
    George S. Bower

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    Feb 24th, 2012 (12:04 pm)

    Nelson:
    I love this kind of info.The one variable missing is ICE fuel consumption at each phase.That would answer my question.Is the Volts ICE more fuel efficient the faster the Volt goes?My guess is yes.

    NPNS!
    Volt#671

    Nelson,
    I am not at home now so I will post an engine map that Tboult found for the Volt ICE later. The SFC islands are clearly marked and the min SFC island is at around 2400 RPM. Faster and Higher loads result in higher SFC (ie lower efficiency). Hwever, Rusty and others on the forum have discovered a “mountain mode gaming scheme that improves fuel consumption in Extended Range mode.

    It involves switching in and out of mountain mode such that the ICE is forced to run at Higher RPM to charge up the battery, then you switch out of mountain mode and the ICE shuts down and you run on the battery. This scheme gets you better ER MPG. Presumably because it increases engine off time (and engine off time is King).”


  15. 15
    George S. Bower

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    Feb 24th, 2012 (12:22 pm)

    There seems to some questions about the negative RPMs on MGB. I wish WOT was here to answer but I am pretty sure that it implies that MGB is generating power. So at the 100 MPH schematic MGB could be generating power and feeding it to MGA.

    Also, I would request that one of you engineers out there calculate some powers from the torques that are shown. I did it by converting N-m to ft-lb and used the equation HP=(ft-lb)XRPM/5252. but not sure I got the conversion to ft lb correct. The numbers I was calculating for HP looked a little high so I don’t know yet what is going on with the torque numbers.

    BTW the torque numbers are calculated by the Volt’s software. The torque numbers are not measured directly with strain gauges like we did on dyno stands at Honeywell (AiR.esearch)


  16. 16
    George S. Bower

     

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    Feb 24th, 2012 (12:30 pm)

    DonC:
    Thanks George and WOT! Nice stuff. Lots of technical details but the big deal is that the sync happens before the clutches engage so we owners won’t experience premature clutch failures.

    I was under the impression that above roughly 70 MPH MGA and MGB worked together to drive the wheels but this suggests that only MGA is powering the wheels. Is that right or am I missing something?

    Yes DonC the other lead article I did showed that MGB was supplying some of the power at 70. However that was at steady state speed not and accel as is shown here. The more power you ask for the higher the ICE speed and at 70MPH the carrier is the same speed only on the accel since MGA speed is higher it drives MGB to lower and lower speeds and finally MGB speed goes negative. So MGB speed being negative is indicative of higher ICE RPMs.


  17. 17
    Noel Park

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    Feb 24th, 2012 (12:30 pm)

    I have a 1917 Chevy 490 speedster vintage race car with the original 3 speed “crashbox” transmission, so believe me, I’m familiar with “double clutching”, LOL!. When I first got ready to drive it I was pretty intimidated, but it actually works OK if you take your time and concentrate.

    I guess that similar technology is what makes proper “paddle shifter” racing car and sports car gearboxes viable. Plant your foot on the gas or the brake, and just pull the paddle and let the electronics do the thinking about throttle blipping and gear speed matching. I’m not going to say that modern racing drivers are spoiled, but……………..


  18. 18
    Chris C.

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    Feb 24th, 2012 (12:36 pm)

    This is great stuff, thanks George and WOT!

    I think it’s important to point out that this transition takes about 2-3 seconds, based on the timecodes at the bottom left of the MDI snapshots. This apparently is the “hesitation” that we feel when we are cruising at highway speeds and we change the accelerator demand.

    I actually feel that hesitation in pure EV mode as well so I’d love to see this same data play out in electric mode. I bet you all have already done that in the forums, but I’ve had no time lately to keep up in there, nor even to play with the cheap OBD2 reader I bought, and so we’re back to me not having time to figure this out for myself :)

    Thanks for the great article that walks us through it.


  19. 19
    George S. Bower

     

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    Feb 24th, 2012 (1:28 pm)

    Chris C.:
    This is great stuff, thanks George and WOT!

    I think it’s important to point out that this transition takes about 2-3 seconds, based on the timecodes at the bottom left of the MDI snapshots.This apparently is the “hesitation” that we feel when we are cruising at highway speeds and we change the accelerator demand.

    I actually feel that hesitation in pure EV mode as well

    That is good input ChrisC I was not sure that those time codes were correct as it seemgg. kind of long.


  20. 20
    Loboc

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    Feb 24th, 2012 (2:22 pm)

    DonC: Not getting the three sources. There are only two sources — the engine and the battery — and only two connections to the wheels — MGA and MGB.

    There are three devices that can spin gears. MGA, MGB and the ICE (through MGA’s shaft).

    The 100mph diagram clearly shows that MGA and ICE have additive torque. If you spin MGB at the same time, then, all three can theoretically supply power to the wheels simultaneously. Add them all up and you get something like 400hp.

    I’m not saying doing this won’t seriously compromise the existing transmission/transaxel (and probably the power converter and battery), however, that’s just design. Beef it up a bit for racing and the possibilities are pretty cool.

    DonC: In practice the Volt hesitates before delivering available power to the wheels.

    I’m pretty sure they are feathering the power so that it doesn’t break something. That’s a serious amount of torque to apply without a torque converter to soften the blow. Since an electric motor supplies full torque at 0 rpm, it’d be like revving up your GTO and popping the clutch.


  21. 21
    Loboc

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    Feb 24th, 2012 (2:33 pm)

    George S. Bower: There seems to some questions about the negative RPMs on MGB

    If you go negative on MGB it would keep the ICE within it’s best power curve.


  22. 22
    pjkPA

     

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    Feb 24th, 2012 (3:46 pm)

    Do we know how this transmission will last compared to ICE tranny?
    I heard GM ran one for 1 million miles… but I didn’t hear the results?
    Has there been any failures? Transmissions or drive motor?


  23. 23
    unni

     

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    Feb 24th, 2012 (3:58 pm)

    Thanks George S. Bower, The article was really informative. I really like to have this kind of an article every week or so.

    Now question :

    Ford’s 3rd generation powersplit hybrid system

    http://www.greencarcongress.com/2012/02/ford-20120224.html

    It’s a simple mechanical arrangement, Gray said, noting that there are no clutches, and no torque converter. The e-CVTs functions to operate either power source in the optimum arrangement. The hybrid system offers four modes of operation:

    Electric drive.
    Engine drive – positive split.
    Engine drive – negative split.
    Regenerative braking.

    How you compare with this to 4ET50. Reason : the other doesn’t have any clutches, torque converters so its for sure better reliability and less maintenance .Same with production cost also . I think in this one also engine direct drive occurs only in 100 mph or so (read some time back ). Why we need complexity when it addresses only a corner case ( 2 motor drive for torque , having a bigger motor should solve ? and totol work around cost will be high than making motor little more big ).


  24. 24
    MichaelH

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    Feb 24th, 2012 (4:17 pm)

    Thanks George and “Senior Moderator” WOT. ;-) Fascinating reading.


  25. 25
    theflew

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    Feb 24th, 2012 (4:50 pm)

    unni:
    Thanks George S. Bower, The article was really informative. I really like to have this kind of an article every week or so.

    Now question :

    Ford’s 3rd generation powersplit hybrid system

    http://www.greencarcongress.com/2012/02/ford-20120224.html

    It’s a simple mechanical arrangement, Gray said, noting that there are no clutches, and no torque converter. The e-CVTs functions to operate either power source in the optimum arrangement. The hybrid system offers four modes of operation:


    Electric drive. Engine drive – positive split. Engine drive – negative split. Regenerative braking.

    How you compare with thisto 4ET50. Reason : the other doesn’t have any clutches, torque converters soits for sure better reliability and less maintenance .Same with production cost also .I think in this one also engine direct drive occurs only in 100 mph or so (read some timeback ). Why we need complexity when it addresses only a corner case ( 2 motor drive for torque , having a bigger motor should solve ? and totol work around cost will be high than making motor little more big ).

    You’re dismissing the fact Ford’s system can’t do 100 mph all electric. Also if you mash the peddle the ICE on Ford’s system will start immediately because of the weak motor. Also if you look at the pictures above the power split on the Volt starts happening at 50 mph in this case. If you accelerated slower it would probably happen at a later point.


  26. 26
    usaisgreat

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    Feb 24th, 2012 (5:03 pm)

    George I have to thank you too, as I just mentioned WOT in the first comment. Great work. Looking forward to reading answers to some of those questions. Also this answered a lot of questions as it proves that the 4th mode does not happen at 70 mph but at any point that the VOLT determines it is most efficient. Also the idea of how it protects the clutches by getting speeds matched too is a nice way to make the transitions.


  27. 27
    unni

     

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    Feb 24th, 2012 (5:21 pm)

    theflew,

    Still more questions :

    2013 fusion :

    It also will be able to travel up to 62 mph (100 km/h) in all-electric mode ( after ICE and motor plays the role )

    Volt: From above : in CS mode :

    70 mph, the transition to power split mode is complete. The ICE is supplying power directly to the wheels thru the ring gear.

    The Volt is going 80 MPH in power split mode. The ICE is supplying power to the wheels (with some power being taken off to charge the battery)

    The Volt is at 100 mph (wow!!), the ICE is supplying power to the wheels

    So where is 100 mph all electric (in Two motor ev driving mode ??? ), This is what my Q is , why not to use a big electric motor which as torque at that speeds and reduce the complexity/unreliability of clutches ?

    Volt works on Single Motor EV Driving, Two Motor EV Driving, Single Motor Extended-Range Driving, Two Motor Extended-Range Combined Driving and Regeneration.

    Now as a common buyer, do you prefer something with 3 clutches etc or simple one because the wear and tear costs are on you for replacing them after x years and they play a role in reliability.


  28. 28
    George S. Bower

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    Feb 24th, 2012 (5:41 pm)

    unni:
    theflew,

    Still more questions :

    2013 fusion :

    It also will be able to travel up to 62 mph (100 km/h) in all-electric mode ( after ICE and motor plays the role )

    Volt: From above : in CS mode :

    70 mph, the transition to power split mode is complete. The ICE is supplying power directly to the wheels thru the ring gear.

    The Volt is going 80 MPH in power split mode. The ICE is supplying power to the wheels (with some power being taken off to charge the battery)

    The Volt is at 100 mph (wow!!), the ICE is supplying power to the wheels

    So where is 100 mph all electric (in Two motor ev driving mode ??? ), This is what my Q is , why not to use a big electric motor which as torque at that speeds and reduce the complexity/unreliabilityof clutches ?

    Volt works on Single Motor EV Driving, Two Motor EV Driving,Single Motor Extended-Range Driving, Two Motor Extended-Range Combined Driving andRegeneration.

    Yes, It would be interesting to make the same presentation for EV mode….That really is what the Volt is all about vs the plug in Ford or the piP. The Volt can run all the way up to 100 MPH in pure EV Mode. That is why the Volt is a real EV and the piP is not. It’s really not about which car is better it’s about what is better for your driving cycle.If you are an EV oriented person then the Volt is the way to go….especially if you are only driving 40 -80 miles per day.


  29. 29
    jeffhre

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    Feb 24th, 2012 (6:23 pm)

    What are you doing George, I thought you were retired. Some engineering a bit of journalism? Great write-up :)

    Dog-Retired1.jpg


  30. 30
    Raymondjram

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    Feb 24th, 2012 (6:47 pm)

    jeffhre:
    What are you doing George, I thought you were retired. Some engineering a bit of journalism? Great write-up

    Being “retired” is not having to work for a living, or not having to work at something you don’t like (the dog is correct!). But every retired engineer I know, including myself, keeps themselves busy and their minds agile by analyzing other engineering wonders, or doing a new one. Besides, some of the world’s geniuses did better work when older (over 50), so we may have a few here on the forum that can help GM improve the Volt.

    Raymond


  31. 31
    Noel Park

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    Feb 24th, 2012 (6:54 pm)

    MichaelH: Thanks George and “Senior Moderator” WOT. ;-) Fascinating reading.

    #24

    Second the motion. +1


  32. 32
    Noel Park

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    Feb 24th, 2012 (6:58 pm)

    unni: Now as a common buyer, do you prefer something with 3 clutches etc or simple one because the wear and tear costs are on you for replacing them after x years and they play a role in reliability.

    #27

    Ford, Schmord IMHO. This is a Volt site, so good luck with that. Based on my recent experience with Chevys, the volt drive line is going to last as long as I want it, so I’m just fine with it.


  33. 33
    Noel Park

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    Feb 24th, 2012 (6:59 pm)

    Raymondjram: Besides, some of the world’s geniuses did better work when older (over 50), so we may have a few here on the forum that can help GM improve the Volt.

    #30

    I should hope so, LOL! +1


  34. 34
    Raymondjram

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    Feb 24th, 2012 (7:18 pm)

    unni:
    How you compare with this to 4ET50. Reason : the other doesn’t have any clutches, torque converters soits for sure better reliability and less maintenance .Same with production cost also .I think in this one also engine direct drive occurs only in 100 mph or so (read some timeback ). Why we need complexity when it addresses only a corner case ( 2 motor drive for torque , having a bigger motor should solve ? and totol work around cost will be high than making motor little more big ).

    The use of clutches shows the superb GM engineering with automatic transmissions. GM developed and produced some of the best transmissions on Earth (and did the Moon Rover, too!), such that many GM vehicles on the road still run with their original transmissions after over 100,000 miles. I have my 1995 Buick Regal with only 138,000 miles (I don’t drive it as much to save gas), yet the clutches are like new and the 3800 CC V6 engine still chirps the tires when I step on the accelerator. The secret is to follow GM maintenance faithfully, and always use the recommended (or better) fluids when doing the routine changes. I strongly recommend the synthetic fluids based on my experiences with the Regal and three previous vehicles.

    Volt owners are following GM procedures to keep their cars running as expected, so I know that the 4ET50 transmission will last many years.

    But Ford deserves to try their own engineering, so we shall see which is more successful. Definitely botth are better than Toyota’s designs!

    Raymond


  35. 35
    Jason Hainer

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    Feb 24th, 2012 (7:21 pm)

    I am waging a war against Volt ignorance, and I need your help. We need to start sticking our necks out for the Volt! I discovered a new article about the volt in the detroit news and I saw hate filled lies about it in the comments. This is the first time I have stood up for the volt and tried to give the facts about it, but it seems to be an uphill battle. Here is the article: http://www.detroitnews.com/article/20120224/AUTO0103/202240341


  36. 36
    Eco_Turbo

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    Feb 24th, 2012 (8:05 pm)

    I understand very little of this engineering stuff, but I do understand what I felt on my two Volt test drives. Pedal to the floor, pressure on my lower back, and no gas engine roar. Try that.., Synergy Drive. 8-)


  37. 37
    George S. Bower

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    Feb 24th, 2012 (9:03 pm)

    Jason Hainer:
    I am waging a war against Volt ignorance, and I need your help. We need to start sticking our necks out for the Volt! I discovered a new article about the volt in the detroit news and I saw hate filled lies about it in the comments. This is the first time I have stood up for the volt and tried to give the facts about it, but it seems to be an uphill battle. Here is the article: http://www.detroitnews.com/article/20120224/AUTO0103/202240341

    Jason you are quite right about the Facts
    1: the Volt project started during the Bush administration by Bob Lutz, a long time Republican that does not believe in Global Warming but loves his country.

    Fact number 2: The GM bailout was initiated by the BUSH administration.

    Fact number three: TARP was initiated during the BUSH Administration.

    The bottom line is that Fox News prints lies…..but after all it is just politics,, right. That is what news is all about.


  38. 38
    Logical_Thinker

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    Feb 24th, 2012 (9:16 pm)

    This stuff is fascinating but honestly after an exhausting day at the office with kids screaming out their lungs at me and (today literally) throwing up from screaming so hard — I can simply point out one fact we need to keep in mind: You don’t have to be an IQ 180 to enjoy the Volt.

    Just get in, and drive. Feel the power. Be happy.


  39. 39
    George S. Bower

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    Feb 24th, 2012 (9:31 pm)

    jeffhre:
    What are you doing George, I thought you were retired. Some engineering a bit of journalism? Great write-up

    Thx Jeff I appreciate that! It really is true. Once an engineer always an engineer. It is ingrained in your brain.


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    kdawg

     

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    Feb 24th, 2012 (11:20 pm)

  41. 41
    kdawg

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    Feb 25th, 2012 (12:04 am)

    Jason Hainer: I am waging a war against Volt ignorance, and I need your help. We need to start sticking our necks out for the Volt! I discovered a new article about the volt in the detroit news and I saw hate filled lies about it in the comments. This is the first time I have stood up for the volt and tried to give the facts about it, but it seems to be an uphill battle. Here is the article: http://www.detroitnews.com/article/20120224/AUTO0103/202240341

    I went to the article and read a lot of the comments. From what I could tell, you were arguing with an old gear head who won’t give up the ICE till the day he dies. Let him keep hanging on to his horse & carriage. The other guy you were arguing with was a lawyer (nuff said) who worships the almighty dollar sign, so he clearly will align with anything GOP and anti-Obama. There’s reallly no point trying to educate these people. They have an agenda. I’m almost at the point, I’d rather just let these people make a55es of themselves, and let the facts speak for themselves. Most people know when they are being fed a line of crap. If they are open minded, they will make a scientific decision. If their mindset is political, it will cloud their thought process, and could cause them to follow a path they normally would not choose. I could also quote Ron White at this time and say “You can’t fix stupid”.

    (disclaimer: I am not implying all lawyers worship the $. However if you read his comments he was going the financial/bailout/sales/etc. approach in his argument. It’s a very hypocritical argument, but it was the one he was making)


  42. 42
    Jon

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    Feb 25th, 2012 (12:03 pm)

    There seems to be some confusion about what the negative numbers mean so let me try to clear that up. An AC motor like the volt has could potentially be operating one of 4 ways:

    1.) Spinning in the forward direction, propelling forward. This is positive speed, positive torque. Requires input current.

    2.) Spinning in the forward direction, propelling backward. This is positive speed, negative torque. Generates output current.

    3.) Spinning in the backward direction, propelling forward. This is negative speed, positive torque. Generates output current,

    4.) Spinning in the backward direction, propelling backward. This is negative speed, negative torque. Requires input current.

    Notice if the sign of the speed and torque are opposite the motor will generate power. If they are the same it needs power. So in the case at the bottom motor MGB is spinning backward but supplying positive torque go it is generating power.

    It would be interesting if these cases showed how much torque each motor and engine were making. Does the MDI tool tell you that?


  43. 43
    Dan Petit

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    Feb 25th, 2012 (12:36 pm)

    What an incredible transmission!
    While I had expected some really refined attributes to the shift routines, this is really beyond what I ever expected. The data shown clearly indicates that there have been a total dedication to apply all of the advantages of both battery energy blending, the generator enhanced power variations, and so much more, that the transmission is very easily understood to be essentially “bullet proof”.

    When teaching transmission rebuilders in independent shops about the external control and damage factors which wear out all transmissions, it is very clear here that GM has applied every kind of technical advantage within this design.

    For example, did you notice that the line pressure sensed is two decimal places in PSI? That is a sensed value of down to under two grams of pressure. Did you also notice that the operational pressures are between fifty and seventy five percent higher than in most transmissions? From the technical perspective, GM has gone all the way to make one outstanding and refined electric transaxle.

    And, as previously mentioned above, there is no possible amount of “shift error”, (slipping usually from either low analog 12 volt values/low wattage to the solenoids), since the Input Speeds are matched by the engine.

    Also clear are the reasons why GM has so many patents.

    **THIS** is a prime example of why it was an accurate decision to stay invested in GM as far as the Federal Loans and to maintain the engineering staff and the Volt programs.

    Once again, I am astonished. If only more folks could understand these completely worthy and solid advancements to the extent that those of us who post here do. These precision designs deserve every technicians’ deepest respect, and, I hope the more than 1200 techs I’ve served (with transaxle and processing diag. seminars) study this post.

    Thanks for the datum, George and WOT.


  44. 44
    CorvetteGuy

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    Feb 25th, 2012 (7:52 pm)

    OT—

    Regular gasoline hit $4.29 per gallon yesterday for us. I did 3 VOLT demo rides yesterday and 3 again today. Everyone wants the new HOV Lane model to get the extra rebates! We will be busy next month when they arrive. :)

    I’m lovin’ it.


  45. 45
    George S. Bower

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    Feb 25th, 2012 (8:06 pm)

    Dan Petit:
    What an incredible transmission!

    Thanks for the datum, George and WOT.

    Thx Dan.

    Looks like the thread is about over. I am glad you tech heads liked it. Thx for the positive feed back, I know I appreciate it and I know WOT does also!!

    Don’t give up the fight!!


  46. 46
    WopOnTour

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    Feb 25th, 2012 (8:49 pm)

    George
    Thank You for spending the time quantifying the data I had collected last fall (and creating the excellent synopsis and power-flow artwork)
    I had good intentions to do just that, but just have been too busy.
    Sorry I also wasn’t able to respond to your last couple of emails as I have been essentially AWOL/AFK since the 19th (took some “personal” days off to go skiing) :D

    You sir are my kind of engineer! (retired or otherwise)
    ALWAYS willing to question and learn through careful and thorough data analysis
    I am sensing that this won’t be the last of our “collaborations”.

    Sincerely
    WopOnTour

    PS> I would also like to acknowledge some excellent “live” Volt data collection being performed by a handful of gm-volt.com forum members (namely Rusty, RScott, pauldon, tboult et al) using the DashDAQ system. Perhaps in the near future they might create a front page article explaining what they have learned as well…


  47. 47
    George S. Bower

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    Feb 25th, 2012 (9:31 pm)

    WopOnTour:
    George
    Thank You for spending the time quantifying the data I had collected last fall (and creating the excellent synopsis and power-flow artwork)
    I had good intentions to do just that, but just have been too busy.
    Sorry I also wasn’t able to respond to your last couple of emails as I have been essentially AWOL/AFK since the 19th (took some “personal” days off to go skiing)

    You sir are my kind of engineer! (retired or otherwise)
    ALWAYS willing to question and learn through careful and thorough data analysis
    I am sensing that this won’t be the last of our “collaborations”.

    Sincerely
    WopOnTour

    PS> I would also like to acknowledge some excellent “live” Volt data collection being performed by a handful of gm-volt.com forum members (namely Rusty, RScott, pauldon, tboult et al) using the DashDAQ system. Perhaps in the near future they might create a front page article explaining what they have learned as well…

    Yes, WOT totally concur. I gave Rusty’s Mountain Mode Gaming Scheme a plug in one of the comments above as I think it is a pretty ggod piece of work (+Scott et all).

    So I would think a slide show like this one today only in EV Mode would be great plus an article from (I think Rusty) on the Mountain Mode gaming scheme.
    It is kind of a pulse and glide version only “Volt Style” if you know what I mean.
    email me the snapshots of EV mode from MDI or give me a link maybe they are on the forum already and I will put them into schematics. EV mode is what the Volt is about after all!!


  48. 48
    Raymondjram

     

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    Feb 25th, 2012 (9:34 pm)

    George S. Bower: Thx Jeff I appreciate that! It really is true. Once an engineer always an engineer. It is ingrained in your brain.

    Very true! There are several engineers here, and I am an EE. All of us appreciate what GM has done with the Volt. And some did buy a Volt (I am still waiting).

    Raymond


  49. 49
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    Feb 25th, 2012 (9:39 pm)

    WopOnTour:

    I had good intentions to do just that, but just have been too busy.
    Sorry I also wasn’t able to respond to your last couple of emails as I have been essentially AWOL/AFK since the 19th (took some “personal” days off to go skiing)

    Sincerely
    WopOnTour

    Well now we know that HTH means “have to hurry” and go skiing!!

    Makes sense to me!


  50. 50
    sparks

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    Feb 25th, 2012 (11:22 pm)

    DonC:

    Having said that, the Volt is very quick in practice. Before the Volt in an Acura which supposedly is faster, when I came up to a line of cars with four or five in the right lane and no one in the left lane, if I wanted to go right at the next light I’d get in the right lane. With the Volt I’ll always get into the left lane because I know I’ll beat the first vehicle in line by 30 or 40 meters. Even if the first vehicle guns it, which has never happened, I know I’ll be able to get behind them because the second car won’t be able to keep up. In doing this I don’t look like a jerk because there is no muss, no fuss, and no noise, and I never get in any other car’s way.

    Exactly, precisely, and spot on! The Volt doesn’t telegraph your assertive intentions. So nobody gets worked up while you are positioning yourself to be in front of the pack. But why do we (I) want to be in front of the pack? Because (this sounds odd, but I swear it’s true) when other drivers notice that you don’t want to waste time, they all accelerate verr-r-r-r-y slowly (with you stuck behind them), to the point that I want to say, “It’s just to the right of the brake pedal … yes, that’s it, now step down on that pedal, and you will notice that you go forward and speed up.” Whereas, if they hear you “revving it,” they will stomp their gas pedal and strive to keep you behind them. So the Volt overcomes all that crap.


  51. 51
    Dave4664

     

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    Feb 26th, 2012 (8:32 am)

    Very well done Jason. I am sticking up for the Volt as well.

    I received this ill informed forwarded note from a friend who did not know I love the engineering in the Volt.

    Hold your nose…this is the ugly kind of war that is being waged against the Volt by idiots (My response follows):
    ———————————————————————————-
    another great example of government social engineering into our lives.
    Subject: Cost to operate a Chevy Volt.

    Cost to operate a Chevy Volt

    Eric Bolling (Fox Business Channel’s Follow the Money) test drove the Chevy Volt at the invitation of General Motors.

    For four days in a row, the fully charged battery lasted only 25 miles before the Volt switched to the reserve gasoline engine. Eric calculated the car got 30 mpg including the 25 miles it ran on the battery. So, the range including the 9 gallon gas tank and the 16 kwh battery is approximately 270 miles. It will take you 4 1/2 hours to drive 270 miles at 60 mph. Then add 10 hours to charge the battery and you have a total trip time of 14.5 hours. In a typical road trip your average speed (including charging time) would be 20 mph.

    According to General Motors, the Volt battery hold 16 kwh of electricity. It takes a full 10 hours to charge a drained battery.

    The cost for the electricity to charge the Volt is never mentioned so I looked up what I pay for electricity.

    I pay approximately (it varies with amount used and the seasons) $1.16 per kwh.

    16 kwh x $1.16 per kwh = $18.56 to charge the battery.

    $18.56 per charge divided by 25 miles = $0.74 per mile to operate the Volt using the battery.

    Compare this to a similar size car with a gasoline engine only that gets 32 mpg.

    $3.19 per gallon divided by 32 mpg = $0.10 per mile.

    The gasoline powered car cost about $15,000 while the Volt costs $46,000.

    So Obama wants us to pay 3 times as much for a car that costs more that 7 times as much to run and takes 3 times as long to drive across country.

    REALLY?

    My response:

    Hi Charlie,
    I hope all is well with you!

    I just had to comment on the Chevy Volt note you forwarded.

    On what planet does electricity cost $1.16 per kwh???!!!

    Hawaii has the highest average residential price of electricity at around 24.2¢ per kilowatt hour in 2009, compared with a U.S. average of 11.51¢.

    My electricity rate just went up…. to 18 cents per kwh.

    Even in Hawaii…. with super expensive 24 cent per kwh electricity……..16kwr X .24 is only $3.84 to fully charge the Volt.

    A full charge of 16kwr is equal to about the energy in .9 gallons of gasoline. Driven conservatively in decent weather….many Volt owners are

    getting well over 40 miles per charge. If you drive less than 40 miles in a day….you use no gas at all.

    Thats the real reason the Volt is under attack.

    I hope to be able to afford a Volt someday.

    All the Best!

    —————————————————————————–

    I hope I got the facts about right. I dont have the time to follow the Volt every day as I work “more than full time” as a technician for a company most folks in the US come in contact with a couple of times a week.

    Thanks to everyone for the great information and comments about the Volt.

    Dave

    Jason Hainer:
    I am waging a war against Volt ignorance, and I need your help. We need to start sticking our necks out for the Volt! I discovered a new article about the volt in the detroit news and I saw hate filled lies about it in the comments. This is the first time I have stood up for the volt and tried to give the facts about it, but it seems to be an uphill battle. Here is the article: http://www.detroitnews.com/article/20120224/AUTO0103/202240341

    Jason Hainer,


  52. 52
    Koz

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    Feb 26th, 2012 (9:05 am)

    Excellent article, George. Your peak into the workings of the Volt’s Voltec “transmission” in CS mode under a specific scenario with real world data does wonders in bringing clarity to what is happening at the heart of the Volt.

    The confusion raised by negative RPMs at the Sun Gear and MGB bears some additional discussion. I think the unavoidable simplicity of line drawings is what is leading to this confusion since the Carrier gear is illustrated by one box symbol. Some may picture it as one gear spinning a shaft (the driveshaft) between the Sun and the Ring gears. In reality the Carrier is actually a set of 4 Planetary gears attached via half shafts to a Carrier Plate, see http://www.motortrend.com/features/editorial/1010_unbolting_the_chevy_volt_to_see_how_it_ticks/photo_01.html#photo. In the first snapshot and the Volt is in series mode; the Sun gear is powered by MGB, the Ring gear is fixed by C1, and the planets are rotated the Sun to rotate the Carrier plate. Looking at a cutaway rendering of the Volt’s 4ET50 “transmission”, http://knudtsenchevyblog.com/files/2010/10/X11CH_VT156L.jpeg, shows the this planetary gearing in place with the motors and output gearing. I think this helps visualize how the RPMs of the Sun and Ring gears can be varied to accomplish the same RPM for the Carrier, once C3 is disengaged. This allows GM engineers to mix and match RPMs and loads on MGA, MGB, and the engine at their whim. This also explains the lengthy fine tuning of the control software during development and it’s complexity.

    For me this shows how easily Voltec could be adapted to higher performance and/or higher load applications, i.e. pickup truck, CUV, minivan, larger sedan, sportscar, etc. I’ve said this before but it bears repeating. GM, add around a 160KW variant of Voltec and open the door. The value proposition is much greater when you are replacing 6-8 cylinder engines that average 20mpg (or less). Let’s go GM!!!


  53. 53
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    Feb 26th, 2012 (10:02 am)

    Koz,

    I agree 100%. GM can do much more than a sedan with its technology. This must be applied across their entire line. But if GM cannot do it quickly, then they must plan and propose this now, and announce this for their future vehicles. Some may call this “vaporware” but future technology announcements generates more interest in GM products, and helps keep GM as a leader when someone is planning for a future vehicle purchase.

    I am one of those who think this way. I have to replace my 1995 Buick Regal, and I was thinking of another Regal or a LaCrosse, but I am waiting and saving for the Volt, while keeping the Regal another year or more. I will never buy an import, no matter how much “technology” they may announce, since most of their “new technology” exists in GM vehicles already.

    Go GM!

    Raymond


  54. 54
    Shaft

     

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    Feb 26th, 2012 (10:25 am)

    For those who are confused about the negative RPM for MG2, this user controlled simulation will be helpful.
    http://eahart.com/prius/psd/
    While based on the Prius, the Volt principles are not significantly different.

    The following youtube video is a pretty good demonstration of how the Prius transmission works. There are a lot of similarities to the Volt but of course they are not exactly the same. But, again, the illustration of principles will be quite valuable in understanding this thread.
    http://www.youtube.com/watch?v=ZmHpSyTsfm0


  55. 55
    kdawg

     

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    Feb 26th, 2012 (9:11 pm)

    Dave4664: Even in Hawaii…. with super expensive 24 cent per kwh electricity……..16kwr X .24 is only $3.84 to fully charge the Volt.

    You should note the Volt does not use all 16KWhs to go 40miles. It only uses about 12.4Kwh. So the cost to recharge is less. (I pay 8cents/kwh btw). Also, it only take 4hrs w/a 240V charger.

    I’d like to see Eric Bolling’s “calculations” to get 30mpg. I’m guessing that number just felt right to him. Also, it wouldn’t take any longer for a Volt to make a trip than a traditional ICE car since you can just keep adding gas, like a traditional ICE car. Oh well, I could go on & on, but I start to question whether these ppl don’t understand the Volt, or they do, and are purposely spreading lies.