EPA says Series Hybrid Better

05-01-2005, 10:13 AM

NewScientist Magazine, April 30 - May 6, 2005, page 25,
"EPA patenting a contorl system for a hybrid in which the wheels are driven by the electric motor powered by a battery that the fuel engine keeps charged up." "WO application 2005/032875"

Toyota gives a pretty good refutation of this idea in their document, link is on PC somewhere, about the THSII system that is used on the Prius
http://www.newscientist.com/article.ns?id=...=mg18624976.400
THS_II Part 1.pdf

bookrats · 05-01-2005, 11:46 AM

Coincidently, I was just wondering about this the other day.

I.e., instead of having the ICE turning the wheels directly, would it be more efficient to have it instead generate electrical power, which would power an electric motor that turns the wheels.

I have a hard time seeing how you don't end up losing energy in the process. Once again, the Toyota HSD just seems friggin' brilliant to me -- particularly the power splitter device.

xevious · 05-01-2005, 05:29 PM

Part of the elegance of the THS/THSII is that it can operate as a parallel or serial hybrid. It's a hybrid hybrid power train!

jayman · 05-01-2005, 07:06 PM

What the EPA describes sounds like how a diesel-electric locomotive works. There is no direct connection between the motor and the drive wheels, it's all electric.

Frank Hudon · 05-01-2005, 07:51 PM

there is always losses in either system. Sure you could probably get by with a smaller ICE but there is no free lunch in this world. That same small ICE coupled with a 15 or 20 speed sequential shifting transmission would probably move the car also. Could you sell them on a large scale? Toyota's hybrid system is probably about as good as it gets currently. Nissan and as Ford found out it's one of the best. Sure Ford's hybrid drive is not a Toyota but so close that to avoid lawsuits licenced some of the patents from Toyota. Nissan on the other hand bought the Toyota system. If they ever use it is another thing. Honda already uses the series system. Not like the EPA is describing but it's still a series system.

xevious · 05-01-2005, 08:58 PM

Quote:

Honda already uses the series system. Not like the EPA is describing but it's still a series system.

Actually, the Honda IMA is a pure parallel hybrid.

richard schumacher · 05-01-2005, 09:02 PM

I want what EPA is smokin'. To get the same performance a series drive needs bigger motors and a bigger generator. Toyota's system lets the engine do some work directly and at the same time overcomes the problem of maximum RPM on an electric motor (1). It's brilliant.

(1) Fuel cell cars may need two motors and a power splitter for the same reason.

Frank Hudon · 05-01-2005, 09:31 PM

Quote:

Honda already uses the series system. Not like the EPA is describing but it's still a series system.

Actually, the Honda IMA is a pure parallel hybrid.

your correct I keep thinking that since the IMA is sandwitched between the ICE and the tranny it's in series but it's actually used in parallel with the ICE to boost output.

05-03-2005, 08:44 AM

The dogma is that the most efficient solution is when an engine is connected directly to the driven wheels, rather than first converting its energy to electricity and then to battery or capacitor and then back to mechanical in a motor to drive the wheels - and this is always used as the main arguement against series hybrids.

BUT it assumes that all engines are equal - they really aren't. Any engine using a gearbox connected to the wheels has to have a whole load of engineering constraints that must be adhered to including (not an exhaustive list!): driveability, smooth idling, high peak power, torque at low revs, ample responsiveness etc etc.

These constraints limit engine design horribly - hence the ~25-30% efficiency of most gas engines. Take away these restraints and you can hit 50-55% efficiency no problem with seriously improved emissions to boot. So a series hybrid would just have a different kind of engine to a normal car and could easily reach over 100mpg before even having to plug-in. See here for more.

DaveinOlyWA · 05-03-2005, 09:25 AM

Frank...knowing all you know about how the EPA tests cars for gas mileage and you are surprised by this?? i'm not... its right in line with their backwards, behind the times thinking

of course, if Toyota had done this method, we would probably have a car that got better gas mileage. tops out at 41 mph and have great torque...

05-01-2005, 10:13 AM	#1
Anonymous Guest Posts: n/a My Car: Package:	EPA says Series Hybrid Better NewScientist Magazine, April 30 - May 6, 2005, page 25, "EPA patenting a contorl system for a hybrid in which the wheels are driven by the electric motor powered by a battery that the fuel engine keeps charged up." "WO application 2005/032875" Toyota gives a pretty good refutation of this idea in their document, link is on PC somewhere, about the THSII system that is used on the Prius http://www.newscientist.com/article.ns?id=...=mg18624976.400 THS_II Part 1.pdf

05-01-2005, 07:06 PM	#4
jayman Senior Member Join Date: Oct 2004 Location: Winnipeg Manitoba Posts: 6,465 My Car: 2004 Prius Package: B Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 4	Re: EPA says Series Hybrid Better What the EPA describes sounds like how a diesel-electric locomotive works. There is no direct connection between the motor and the drive wheels, it's all electric.

05-01-2005, 07:51 PM	#5
Frank Hudon Senior Member Join Date: Jan 2004 Posts: 4,144 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Re: EPA says Series Hybrid Better there is always losses in either system. Sure you could probably get by with a smaller ICE but there is no free lunch in this world. That same small ICE coupled with a 15 or 20 speed sequential shifting transmission would probably move the car also. Could you sell them on a large scale? Toyota's hybrid system is probably about as good as it gets currently. Nissan and as Ford found out it's one of the best. Sure Ford's hybrid drive is not a Toyota but so close that to avoid lawsuits licenced some of the patents from Toyota. Nissan on the other hand bought the Toyota system. If they ever use it is another thing. Honda already uses the series system. Not like the EPA is describing but it's still a series system. __________________ You can quote me on this, People who drive vehicles that idle at a traffic light, are idiots. mine 2k3 avg. 5.36 for 46,915Km Best tank 4.4L per 100K 64.2 Imperial 53.4 U.S. gallon, MiniScanner, SilverStars, block heater, winter lips, in as of Oct 15, out on April 25. In again on Sept. 21st. her's 2k4 "B" avg. 6.01 for 42,317 Km Best tank 4.02L per 100K, CAN-view with OBD11 module and flashloader, SilverStars, 06 Chrome grill bar, Michelin HydroEdge, upper and lower grill blocker,upper out as of April 7, lower out on April 28. In again on Sept 21st.

05-03-2005, 08:44 AM	#9
Anonymous Guest Posts: n/a My Car: Package:	Re: EPA says Series Hybrid Better The dogma is that the most efficient solution is when an engine is connected directly to the driven wheels, rather than first converting its energy to electricity and then to battery or capacitor and then back to mechanical in a motor to drive the wheels - and this is always used as the main arguement against series hybrids. BUT it assumes that all engines are equal - they really aren't. Any engine using a gearbox connected to the wheels has to have a whole load of engineering constraints that must be adhered to including (not an exhaustive list!): driveability, smooth idling, high peak power, torque at low revs, ample responsiveness etc etc. These constraints limit engine design horribly - hence the ~25-30% efficiency of most gas engines. Take away these restraints and you can hit 50-55% efficiency no problem with seriously improved emissions to boot. So a series hybrid would just have a different kind of engine to a normal car and could easily reach over 100mpg before even having to plug-in. See here for more.

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05-01-2005, 11:46 AM	#2
bookrats Senior Member Join Date: Mar 2004 Location: Seattle, WA Posts: 2,843 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Coincidently, I was just wondering about this the other day. I.e., instead of having the ICE turning the wheels directly, would it be more efficient to have it instead generate electrical power, which would power an electric motor that turns the wheels. I have a hard time seeing how you don't end up losing energy in the process. Once again, the Toyota HSD just seems friggin' brilliant to me -- particularly the power splitter device.

05-01-2005, 05:29 PM	#3
xevious Join Date: Jan 2004 Location: Oregon Posts: 187 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Part of the elegance of the THS/THSII is that it can operate as a parallel or serial hybrid. It's a hybrid hybrid power train!

05-01-2005, 09:02 PM	#7
richard schumacher nacreous lacquer Join Date: Mar 2004 Location: United States Posts: 4,131 My Car: 2004 Prius Package: #6 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	I want what EPA is smokin'. To get the same performance a series drive needs bigger motors and a bigger generator. Toyota's system lets the engine do some work directly and at the same time overcomes the problem of maximum RPM on an electric motor (1). It's brilliant. (1) Fuel cell cars may need two motors and a power splitter for the same reason.

05-03-2005, 09:25 AM	#10
DaveinOlyWA Opps !! I Did it Again!! Join Date: Apr 2004 Location: South Puget Sound, WA Posts: 9,676 My Car: 2006 Prius Package: #4 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 5	Frank...knowing all you know about how the EPA tests cars for gas mileage and you are surprised by this?? i'm not... its right in line with their backwards, behind the times thinking of course, if Toyota had done this method, we would probably have a car that got better gas mileage. tops out at 41 mph and have great torque...