If we are totally realistic here, this is really a debate about engineering philosophy and new product development philosophy. I have said in the past that hybridization in the future, or rather short-term future, isn't going to be the Toyota way, which is to have unique vehicles which are hybridized and then a regular line of cars that are not. Honda has a better philosophy in that matter which is that hybrid technology is a power train option and as such it can be mated to any platform you can justify doing it to, of course within engineering and manufacturing limits.
On the other hand, we have not seen the end of hybrid development. All manufacturers with hybrids are playing their cards very close to their chest, and it will remain that way for many years to come. In fact, hybrid development is so far one of the first really cutting edge technologies which makes car manufacturers have to play by the same R&D rules and procedures as software and hardware manufacturers; i.e. non-disclosure of unique developments, protection of intellectual property, etc. In the past manufacturers basically built the same stuff and the intellectual property was sent out the door with every customer because every vehicle could be disassembled and analyzed by just about anyone who wanted to do so. The same holds true for mechanical hardware today, but the software that controls all the mechanisms, well that is where it is more like the software industry than the car industry.
Ok, that was a bit off topic, but I think it needed to be said.
Toyota has figured out that hybridization is a power train option now and as such we will see HSD in many different platforms. But the one thing we haven't seen out of hybrid makers yet is true real wheel drive, the kind you would see in pickups and heavy iron sedans. I know it can be done, however it is a matter of time until that will be done. If I were to take a guess Ford will be the first to do it because they have successful auto platforms which are not front drive, and they have no intention of making them front drive (Crown Victoria, Grand Marquis, Town Car) along with pickups.
The crux of the issue between IMA and HSD is development procedure and desired outcomes. IMA was meant to increase fuel economy through many different means, including lean burn, auto stop, use of conventional (if you can call it that) CVT and inclusion of an assist motor. So, Honda chose to build a vehicle with technologies and devices which required further refinement, but not a whole lot of totally unique development. Benefits: faster to market; easier to engineer, build and refine; greater room for incremental improvement or small adjustments for alternate platforms; totally conventional driving experience, aside from auto-stop. Drawbacks: auto-stop engine functionality rather than true EV mode (no stealth mode); electric system is more of an appendage (technical opinion), not central to basic operation, but essential for fuel economy and quality performance, reliance on many (but not all) conventional pulley based accessories due to limited electrical generation capabilities (only regen electric generation, no direct generation).
HSD isn’t perfect, however it addresses some of the drawbacks of IMA, specifically generation of reserve power independent of vehicle movement; auto-stop functionality which can happen not just at lights, but also while driving under the correct conditions; almost no reliance on pulley based accessories, due in part to an efficient electric a/c compressor and almost unlimited electrical power to run it. And this also points back to the beginnings of Toyota’s hybrid development project. They weren’t just developing a power train, they were developing an entire car. The engineering mindset when designing a vehicle is very different when you are developing an entire vehicle platform from the ground up rather than just a way to hybridize any old vehicle in your current catalog. That difference in mindset is probably the leading difference in how the two companies came to hybridization so differently and why Honda’s offerings and Toyota’s offerings are so very different.
It has been said: Hybrid drivers come in 3 flavors, greenie, techie and cheapie. Pick any 2.
2005 Prius, Melinium Silver over gray, package 5 (AI)
___Since I loved to expose the truth of some of USB’s Pro Prius posts from way back, let me give you a few other sides of the equation.
1. Do you know how much torque 295 Ft.-Lb’s is? Toyota says it is available in the Prius II yet the performance shows something completely substandard to this proclamation. I have never seen that torque curve in anything but a Toyota press release. Bench the electric motor at 1 RPM and it might output 295 Ft.-Lb’s but connect your Prius up to my 5,000 # landscape trailer and attempt to take off and she will be standing there squealing in absolute pain. The Ranger XLT on the other hand with maybe 75 Ft-Lb’s at less then 1,500 RPM’s will tow that trailer right up to speed without nearly a concern. There are lies, and there are **** lies. Pick your poison …
2. Otto cycle ICE’s have the best efficiency out on the highway? No, they have the best efficiency at the most minimal throttle opening and lowest RPM, to maintain speed while in top gear if the automobile were designed properly. You have to consider the system, not an ICE’s Engine MAP. Have you ever driven an Insight 5-speed at 35 mph on a flat road in 5th gear? 130 + mpg is in the offing. Ever drive 35 mph on a similar road in a Prius I or your II? The throttle openings in both ICE’s are at absolute minimums (just above idle) and the Prius I and II’s HSD logic attempts to maintain the tallest gear ratio available. This is how you hit 95 + mpg over a relatively short segment or 900 + mile tanks in your own. Again, you have to consider the system because 35 mph in either is nowhere near ~ ½ throttle opening as the Engine maps of the Prius II portray where the best efficiency lye’s. A quick study of my Insight’s gauge cluster pics in the “Attempt …” thread as well as Krousdb’s Prius II record run description will tell you all you need to know in this regard.
IMA was meant to increase fuel economy through many different means, including lean burn, auto stop, use of conventional (if you can call it that) CVT and inclusion of an assist motor.
I don't know what exactly we talking about in this debate. The title is IMA vs HSD which implies to me that we are talking drive train only. For example if Honda put in an Atkinson cycle engine (or even a Diesel) it would still be called IMA so long as a single motor "helper" was used. Some of the other features we have talked about are really not part of the IMA or HSD system. What are we suppose to be talking about?
Ok, the 'fight' has been started, but lets move it to its own topic and quit hounding the discussion of the HCH passing the Prius in FE. I believe the question that started the discussion was weither Honda's IMA system was scalable and wether or not Honda could improve on its city milage enough to make it competition for the Prius in that arena.
HSD isn’t perfect, however it addresses some of the drawbacks of IMA, [1]specifically generation of reserve power independent of vehicle movement; [2]auto-stop functionality which can happen not just at lights, but also while driving under the correct conditions; [3]almost no reliance on pulley based accessories, due in part to an efficient electric a/c compressor and [4]almost unlimited electrical power to run it.
I'd like to address your points one-by-one:
(1) The IMA system can generate electricity w/o moving.
(2) The IMA system can auto-stop "under the correct conditions" too.
(3) The IMA is not reliant upon pulley-based systems, as evidenced by the Accord IMA which uses electric steering, electric fluid pumps, and electric A/C.
(4) The IMA also has a large battery and "almost unlimited electric power"
"I'd like to address your points one-by-one:
(1) The IMA system can generate electricity w/o moving.
(2) The IMA system can auto-stop "under the correct conditions" too.
(3) The IMA is not reliant upon pulley-based systems, as evidenced by the Accord IMA which uses electric steering, electric fluid pumps, and electric A/C.
(4) The IMA also has a large battery and "almost unlimited electric power" "
I'm not a Honda expert here, please let the rest of us know the hows and whys to your answers above. Any websites that can help?
I'm curious about the IMA system and will be honest, I thought it:
1) only had one electric motor so it can't create electricity to charge the battery while it is assisting,
2) the engine has to spin in order to deliver power to propel the car (electric can't move the car on it's own,
3) There ARE pulley systems in the Civic and Insight hybrids AND in the Accord (with the Accord having electric systems also), and
4) what is the output of the Civic battery, 144 volts? The Accord hybrid must be higher? Unlimited is vague, even my Prius has 202 volt battery and an inverter to bump it to 500 volts useable to the electric motor.
Really, I want to learn more about the IMA. It seems to work. I see HSD as far surperior these days. My opinion, but very well may be based on my lack of IMA knowledge! Thanks.
'04 Seaside Pearl #7. Fumoto oil drain, mudflaps, rear bumper scuff protector & rear warn system, compass mirror, EV mode button, 8" subwoofer in right rear cubby & 6" subs under seats, power lumbar in the front seats, Coastaletech hitch w/ Aspen bike/snowboard rack. iPod2car, 2 amps, Alpine component speakers, and DVD video, solid 47 MPG @ 70000 miles.
Wayne, you wrote "2. Otto cycle ICE’s have the best efficiency out on the highway? No, they have the best efficiency at the most minimal throttle opening and lowest RPM, to maintain speed while in top gear if the automobile were designed properly"
The best speed (that is, the highest mpg) of 35 - 40 mph on level roads in the Prius, and apparently the Insight from your experience, is due to the conflicting energy losses due to ICE partial power at low speeds, and air friction at higher speeds. Assuming that best mpg conditions implies most efficient engine use is wrong.
I'm not a Honda expert here, please let the rest of us know the hows and whys to your answers above. Any websites that can help?
I'm curious about the IMA system and will be honest, I thought it:
1) only had one electric motor so it can't create electricity to charge the battery while it is assisting,
2) the engine has to spin in order to deliver power to propel the car (electric can't move the car on it's own,
3) There ARE pulley systems in the Civic and Insight hybrids AND in the Accord (with the Accord having electric systems also), and
4) what is the output of the Civic battery, 144 volts? The Accord hybrid must be higher? Unlimited is vague, even my Prius has 202 volt battery and an inverter to bump it to 500 volts useable to the electric motor.
Really, I want to learn more about the IMA. It seems to work. I see HSD as far surperior these days. My opinion, but very well may be based on my lack of IMA knowledge! Thanks.
I suppose I fit into finman's shoes about this one. His beliefs are basically mine also, on these points.
On a point by point basis for those who are more knowledgible to respond to:
1. For background, the Prius has what is commonly reffered to as a deadband. Meaning that under certain driving conditions the vehicle will actually run the ICE at a certain RPM sufficient to both send power directly to the wheels and send power to MG1 which is then all consumed by MG2 and none is sent back to the battery. This is probably the best exampel of the Prius's charge/drive state. I do not see how this could be done with only 1 MG on board? Is there any clarification on this issue out there.
2. Again, I was under the impression that IMA was not configured in such a manner as to be able to move the vehicle in an electric only fashion. Clarification?
3. I apologize for not stating that I was not thinking about the Accord hybrid when speaking about pulley based accessories. I do understand that the A/C compressor is both pulley and electric, and I'm under the impression that the control logic favors pulley drive when the vehicle is moving. I'm not concerned about engine drag from the a/c because the Accord is a V6. But to be honest, moving away from pulley based accessories and toward electrically based accessories is a major step forward for hybrid efficiency. Anyone familar with the previous Prius design knows how draining the a/c is on a hybrid engine when you are at a stop and the auto system decides it needs to kick in. I admire Honda for creating that Econ mode while running A/C so autostop works as expected, however that means that the vehicle may get a little bit warmer than usual in some traffic conditions.
It has been said: Hybrid drivers come in 3 flavors, greenie, techie and cheapie. Pick any 2.
2005 Prius, Melinium Silver over gray, package 5 (AI)
The best speed (that is, the highest mpg) of 35 - 40 mph on level roads in the Prius, and apparently the Insight from your experience, is due to the conflicting energy losses due to ICE partial power at low speeds, and air friction at higher speeds. Assuming that best mpg conditions implies most efficient engine use is wrong.
___It isn’t air friction by as large margin as you would think at the lower speeds where the Insight, Prius II and most other automobiles really shine. It is rotational friction (mechanical based) that kills FE as you move up the RPM range up to maybe 50 - 55 mph + when aerodynamic losses become more prevalent. Check out some of the other Prius II NREL powertrain data. You will find dramatic logarithmic power losses in the HSD as RPM’s climb through a very small RPM operating range. This is on a motor only dyno independent of any aero losses since there are none! Smaller throttle openings is not the Achilles’ heel of the Otto cycle ICE’s at low RPM’s for hypermilers. It is the higher RPM frictional losses of the drivetrain as a system from what I have experienced. Run any Otto cycle engine in their peak efficiency at 2,500 + RPM’s (wherever the peak efficiency of a given ICE lye’s) with a shorter gear and your FE will stink vs. that same engine not running at its peak efficiency (1,300 RPM for example) at the exact speed with taller gearing. The lower RPM ICE running in the far less efficient mapped area will kill the higher revving, much more efficient (per the engine map) ICE in FE every time! I am talking about system efficiency (real world FE), not HP available at a given RPM, not 30 - 60 mph available performance, or anything else. Just pure FE from a small range of RPM’s in a given ICE. You cannot accelerate hard from just above lug where these hyper efficient areas lye (system FE again, not an Engine map) but you can receive outstanding FE at this low RPM, low load range where the engine maps say the ICE is just about useless in terms of absolute fuel burned to power output. A good example … I could run > 110 mpg in the Insight when idling in third or gear when just warming her up in temps > 60 degrees. We are talking about 1,100 - 1,200 RPM in 3rd gear just above the point of lugging! Do you know what the Insight’s ICE efficiency map must look like at 1,100 RPM from cold? Easily less then 30% yet she would idle away allowing outrageous FE for that period with an absolute minimum throttle opening.
___You are the one who insinuated “that best mpg conditions implies most efficient engine use …”, not me. Your linking of the Prius engine maps was the first mistake.
Re: HSD vs. IMA vs. ...
