What is this GM 2-state hybrid concept? - GreenHybrid

JeromeP · #1 (**permalink**) 01-11-2005, 06:48 PM

I either haven't been looking hard enough or... But can somebody explain to me or point me to a web site which gives a good explaination of what this GM 2-stage hybrid is all about? Anything will do. I'm trying to create a mental picture (or any other picture for that matter) about how all the pieces fit together.

xcel · #2 (**permalink**) 01-11-2005, 07:48 PM

Hi JeromeP:

___It appears to be an Allison designed transmission with the hybrid electrics inside.

___The best description I have read about the design was an article entitled “GM-DaimlerChrysler’s Two-Mode Full Hybrid System – Versatile for any Market” over at The Auto Channel:

Quote:

The flexible and cost-effective two-mode full hybrid system will leverage automatic transmission technology and electronic controls in an integrated, powerful and compact system that can be used with a variety of engines, both gas and diesel. The system will easily configure to rear-, front- and all-wheel drive versions for cars, trucks and other vehicles, making the two-mode full hybrid one of the most versatile, best performing and cost effective packages in the industry. The technology is expected to improve acceleration performance while also improving vehicle fuel economy and range …

Patented two-mode full hybrid

GM’s two mode full hybrid system has been established as the starting point for the GM-DaimlerChrysler collaboration. The design integrates proven automatic transmission technology with a patented hybrid-electric drive system to deliver the world’s first two-mode full hybrid. In full-size truck and SUV applications, the system enables at least 25 percent fuel economy savings and superior performance.
Two-mode system innovations also allow for more compact packaging because its compact and powerful electric motors are designed to fit within the approximate space of a conventional automatic transmission – an efficiency advantage compared with today’s typical single-mode systems that rely on much larger electric motors.

“It’s the optimal merging of full hybrid and state-of-the-art automatic transmission technologies,” said Stephens. “The system is essentially an electrically variable transmission with two hybrid drive modes. We’ve taken the two-mode hybrid technology that we are using in transit buses and improved it further for use in our popular rear-wheel drive SUVs and pickups, and front-wheel drive cars. Single-mode systems can’t provide the range of operating efficiencies that our two-mode system can. Our system reduces fuel consumption at highway speeds much more effectively.”

Compact and powerful electric motors are integrated into the transmission and work with traditional transmission gears and electronic controls to provide two modes or ranges of infinitely variable gear ratios. The input split mode is used for launching the vehicle from a stop, driving at low speeds and providing superior performance and moderate load trailer towing. The compound split mode is used primarily when the vehicle is at higher speeds to provide efficient cruising.

The drive modes alternate seamlessly between the input split mode and a compound split mode. In the input split mode the vehicle can operate on electric, mechanical or a combination of the two. The vehicle operates as a full hybrid when the engine is shut off at low speed and light loads, as leaving the engine off for extended periods of time and moving under electric power is key to reducing fuel consumption in stop and go traffic.

Coupled with the efficient compound split mode, the electronic controller seamlessly integrates with other fuel-saving technologies of advanced engines, such as ultra-high compression ratio, Late Intake Valve Closing (LIVC), Cam Phasing and Displacement on Demand (DoD) to regulate cylinder deactivation. Electric motors not only regulate the power flow, but also aid in extending DoD operation well beyond what is capable without hybrid assist. In addition to electric assist, full –size engine power is on tap whenever higher-load situations demand it, such as towing, climbing steep grades, etc.
“It all happens without the driver realizing it,” said Larry Nitz, executive director of GM’s hybrid program. “There are no discernible steps between modes or DoD transitions. The two-mode full hybrid simply optimizes power and torque for the given driving conditions, and all the driver feels is the satisfaction of low fuel consumption and the exceptional reserve power and performance.”

The addition of a second mode to the drive system improves efficiency and reduces the need for exceedingly large electric motors, typical with today’s single-mode systems. The resulting scaleable architecture enables faster proliferation of the technology to a wide range of engines and vehicles, from compact cars to trucks and even 60-foot buses.

“Typical single-mode systems depend on large electric power loops between two large electric motors, resulting in inefficiency and ultimately less continuous power,” said Nitz. “The two-mode full hybrid delivers seamless, dependable power on demand and in a more efficient power flow – and is packaged with motors less than half the size of single-mode systems.”

A sophisticated controller determines when the vehicle should operate in either mode of the two-mode drive system. Input from the controller determines the necessary torque for the driving conditions and sends a corresponding command to the engine and electric motors. The engine and electric motors transfer torque to a series of gears in the transmission, which multiply torque similar to a conventional automatic transmission to propel the vehicle. But unlike conventional continuously variable transmissions, the two-mode full hybrid’s electrically controlled system uses no mechanical belts or bands. Shifts between the two modes are synchronous, which means no engine speed changes are necessary for the mode shift to occur, resulting in ultra smooth accelerations.

The 300-volt battery pack provides electric power for the system, and while it is larger than a typical automotive battery, it is designed to fit in the vehicle without compromising passenger space. Special converters located under the vehicle’s hood convert the motors’ AC output to DC current and power conventional 12-volt accessories, such as interior lighting, climate control and the radio. The vehicle’s internal combustion engine provides power to charge the battery pack, so the vehicle doesn’t have to be plugged in to keep the battery pack maintained.

Because the architecture can be scaled to fit multiple vehicles and adapt to gasoline or diesel engines, the-two mode full hybrid can be fostered in markets around the world. In Europe , for example, where diesel engines are common in passenger vehicles, it can provide a significant reduction in fuel consumption, which would help automakers meet the region’s ever-stringent carbon-dioxide emissions standard “We have several additional propriety innovations that will make the two-mode system even more capable in high-power to weight ratio vehicles, such as in SUVs and full–size pickups…innovations that combine our two-mode full hybrid with our extensive capability in step gear automatic transmissions and electronic control systems,” said Stephens. “We believe it is the most efficient full hybrid design for a broad variety of vehicle configurations.”

___Given GM’s hybrid initiatives to date, it sounds like a lot of hot air but the pics I have seen show just a std. sized transmission and if so, it could be implemented in every automobile far easier then Honda’s IMA, Toyota’s HSD, and Ford’s own.

___Good Luck

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___Waynegerdes@earthlink.net

JeromeP · #3 (**permalink**) 01-12-2005, 11:11 AM

Thanks for the link and the quote. That is very helpful, however I have to agree that it seems a little bit of pie in the sky.

EdW · #4 (**permalink**) 02-28-2005, 08:02 AM

I don't have a doubt that GM and DaimlerChrysler could do this if they really mean business. My main worry, though, is that considering GM's recent experience with its CVT and DaimlerChrysler's dismal quality reputation, will it be able to hold a candle to Toyota or Honda reliability?

ericbecky · #5 (**permalink**) 02-28-2005, 09:51 AM

I do not think it is pie in the sky. It seems very possible. I have seen a model and read a lot of material. I'm working on an article to explain it, but it will be a little while before I have it done. I'd like to talk to someone on the design team to get more details.
The fact that it is housed within a standard transmission make it very fexible to fit in various applications, front wheel drive or rear wheel drive.

JeromeP · #6 (**permalink**) 03-01-2005, 11:14 AM

I look forward to your document. I still don't have a clue what constitutes a 2-stage system.

lakedude · #7 (**permalink**) 03-02-2005, 06:30 PM

If I'm reading it right dual mode refers to "Stealth mode" or ICE off "electric only" mode. The system sounds basically like the one in the Prius as opposed to the one in the Hondas. Hondas do not have an "electric only" mode.

I have zero confidence on GM or any US auto maker to come out with anything worth a crap, unless it a copy of a Japanese car. Quite a change from when the situation was exactly reversed in years past.

Toytech · #8 (**permalink**) 03-03-2005, 04:51 AM

The Prius electric motors are housed in the transmission, in fact the variable speed trans. wouldn't work without them. The two electric motors are connected to different parts of a single planetary gear with the gas engine to produce the variable ratios. It's quite the slick system.

EdW · #9 (**permalink**) 03-03-2005, 07:53 AM

I question GM's quality, as well. But they're definitely getting better. According to J.D. Power & Associates, Consumer Reports, and just about any other publication you care to read, the domestics as a whole are improving significantly. It's to the point that American cars collectively are more reliable than European cars, and GM's Buick division rated higher than Toyota in J.D. Power's last long-term dependability survey.

GM isn't at the level of the Japanese, but they're trying. They'll get there, too, if they work at it hard enough.

PRO_USA · #10 (**permalink**) 05-23-2005, 10:28 AM

Being from the Detroit Metro area, I am a GM and Ford supporter. Having said that I will not buy a new car unless it uses some type of alternate fuel, gasoline hybrids don't count. What I want is a hybrid electric that uses E-85 (85% ethanol, 15% gasoline) or some other fuel. Or how about a Hydraulic Hybrid? I have heard a lot of good things about them. In fact I am going to test drive an Eaton based Hybrid next week. I'll report the results next week.

GM will have a hit with their Dual mode hybrid, it is a commercial success with their buses and its about time!