In revising the second-generation Chevrolet Volt, General Motors re-designed its electrical/mechanical transaxle, and one might now pose the question whether this same design would be ideal to use in a super fuel-saving truck such as VIA Motors now makes.
VIA builds pure series plug-in hybrid trucks based on the Chevrolet Silverado and other light-duty GM trucks.
The Oregon start-up’s Mexico-based facility takes whole GM trucks from a nearby production plant, tears out the drive train and retrofits whole new plug-in hybrid systems with up to “100 mpg” averaged efficiency.
GM itself had a 2-mode hybrid it discontinued and there is a gaping hole in this gas-guzzling segment. Following is a look at the possibilities …
A Superior Design
A week ago on the GM-Volt forum, an exclusive article was posted on the Voltec transmission showing it cuts cost and weight while increasing vehicle performance and efficiency.
The lower cost is achieved through the new motor designs which use fewer rare earth metals. Most importantly GM is now additively linking the two motors in EV mode so they can get by with a smaller main traction motor but still end up with the same total power in EV mode as before. In short more for less.
Could this same theory be used in an ‘EREV’ truck?
It seems to me that the answer is an unequivocal yes. GM could create an extended-range electric truck that would be lower cost than a pure series hybrid truck. In other words, GM could out VIA VIA.
The VIA truck has one big traction motor and a generator driven by an internal combustion engine like Gen 1 Volt. GM can get by with lower motor costs than the pure series arrangement by linking the two motors and also offer more efficient operation in extended-range mode since all the pure series conversion losses are eliminated. GM has eliminated pure series as an operating mode in the new Volt transmission.
We are all aware that GM produced a 2-mode hybrid transmission for the Silverado truck. Although much maligned as a failure it was actually an engineering work of art. Its downfall was that GM charged too much for it and never really tried to lower costs and finally it was cancelled.
All the cost cutting features that GM used in the new Gen 2 Volt transmission should apply to a truck transmission. The two units are very similar from a technical point of view. Both transmissions have identical hybrid modes: input split and compound split. The rest of the modes are just fixed gear ratio modes: gen 2 Volt has one fixed gear and the Silverado 2 mode had four fixed gears. The old 2 mode had three planetary gearsets and four clutches so it had one more clutch and one more planetary gearset than the gen 2 transmission.
Of course the Silverado transmission did not have an EV mode but that could easily be added since all the hardware components are the same.
Therefore not only could GM make a pure hybrid version of the transmission they could also make an extended range version.
Granted, an EREV version seems like a long shot but a plain hybrid version does not. Personally I think that it is just a matter of time until mileage requirements dictate that configuration anyway. Both Ford and Toyota are rumored to already be working on one.
GM just beat all the other EV makers to the punch with their new 200 mile Bolt EV.
Could GM be first on the market with a successful version of a hybrid truck … or better yet an extended range electric truck? What do you think?
George Bower is a retired aerospace engineer, Prius and Volt owner, motorcyclist, long-time reader and occasional tech writer for GM-Volt.com.