Filed under: In the Autoblog Garage, Hybrids/Alternative, SUVs
2005 Ford Escape Hybrid: In the Autoblog Garage Days 3-4
Ford's approach to hybrid technology has some similarities with that of Toyota's Synergy system, however there are some key differences.
In the Escape application, Ford has decided to use an Aktinson-cycle four-cylinder as well as active battery cooling.
Ford also integrates their high voltage hybrid components into the transaxle, which simplifies the engine compartment
and helps prevent damage. The battery life and power is increased by using the auxiliary battery cooling system. The
Aktinson-cycle engine offers improved fuel economy, while sacrificing low-end power. This sacrifice is well matched
with the instant power available from the electric traction motor.
There are actually two electric motors in the Escape Hybrid. One 70 kW traction motor and one 45 kw generator/motor
both contribute to the hybrid's powertrain. How this system works is actually pretty amazing. I will try my best to
relay it to you accurately. The schematic below will show you the relationship of the hybrid's components. The
planetary gearset is crucial to the operation of the entire system. Its simplicity is quite elegant.
The system has three modes, Electric vehicle mode, positive split mode, and negative split mode. There is also an idle
charge mode, but that does not contribute to the vehicle's direct motivation.
In electric vehicle mode, the traction motor draws energy from the batteries to propel the car without using the
gasoline engine. At this point, the gasoline engine is off. When in this mode, energy is also collected when the
vehicle is slowing down. This regenerative braking is done in the other modes as well. The diagram below shows how the
regenerative braking torque contributes to the vehicle's deceleration effort.
In positive split mode, the gasoline engine is on and works in concert with the traction and generator motors to power the vehicle at moderate speeds or loads. In this mode, the generator is producing energy from the gasoline engine's output. This energy can be used to charge the batteries or power the traction motor. The traction motor also contributes to the Escape's motivation.
During high speed or high load situations, the system operates in negative split mode. In this mode all three power
plants are contributing to the vehicle's movement in some way or another. The generator motor operates to reduce the
gasoline engine speed required while the traction motor operates as a generator to provide power to the generator
motor.
The electrically controlled CVT or eCVT does not have the belts and chains typically found in other CVTs. Instead
the motors and planetary gear set work in harmony to operate in the most efficient manner possible. The planetary gear
set allows the contribution of the gasoline and generator motor to vary depending on the situation.
So what do we think of all this? It all works very seamlessly. In fact, the shutdown and start up of the motor is
hardly noticeable unless you're watching for it. The power delivery is smooth, and there is a surprising amount of
power available. Off the line, it is not that fast but once you are moving the entire hybrid powertrain can accelerate
the Escape briskly. The Hybrid information screen will give you a diagram of what mode the system is running in, but if
you're not paying attention to the system it operates fine on its own.
The sensation of driving a hybrid is a different from what most people experience in normal cars. Hearing the whine of the electric during assist or regeneration is strange at first, but then becomes a novel reminder that you're driving a hybrid. Of course, you can't really hear it with the radio on, but roll down the windows and turn off the radio. Then you can experience the eeriness of rolling way from a stop light with the engine off as well as the other audible indications of the hybrid's operation. This car would be great for the kid who lives at home and wants to avoid getting caught on those late night returns. No need to turn the engine and the lights off to coast in with stealth. Just stop a safe distance away, let the engine stop, and cruise in under 25 mph in the silent EV mode. How useful this would've been in our youth!
We did have a couple complaints. With any CVT transmission, you have to contend with engine noise. The engine noise
is really only a problem when accelerating, and is simply off-putting to the uninitiated. The other complaint is with
the air conditioning when the engine shuts off. The AC simply does not cool when the gasoline engine is off, in EV mode
or when you are idle. You can prevent this engine shut down with the AC set to Max AC, but that defeats the purpose of
having a hybrid. The AC compressor should probably be driven by another electric motor to keep the passenger
compartment cool. Ford has openly told us they have made a substantial effort to improve this problem in the 2006
models. Ford has also made some tweaks to the rest of the hybrid system to make it operate even smoother.
Based on what we've seen so far, we look forward to this power system finding its way into other Ford products. We
could see where such a system would help give the Five Hundred more power or give Volvo a competitor to the Lexus
RX400h in an XC90 Hybrid.
Also, look for an upcoming podcast where we interview Tom Gee with Ford's Hybrid team.
Reader Comments (Page 1 of 2)
Craig Weems 10:45PM (12/18/2005)
Do you realize how big an electrical motor would have to be to power the A/C? Big, really big. The batteries run time would be far shorter too. The answer? Some type of buffer for the A/C. Something of some mass(phase change?) that would be chilled as you drove. When you stopped the A/C would use the stored "cold" to chill the air. On most start and stop driving it would work great. The engine would turn on only after the A/C was unable to keep up. Far easier than addig a BF motor.
Should I patent this?
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Jon 10:45PM (12/18/2005)
Umm, the Prius has an electric A/C compressor. It runs off the battery so you stay cool when the engine's off.
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Spinteews 10:45PM (12/18/2005)
Ford is using Toyotas 1st generation Hybrid system. The current Prius is using the 2nd Generation Hybrid system while the Highlander and Rx400h is using the 3rd gen.
That system is pretty much exactly the same as the Toyotas version, Nissan is going to be using the same thing also, based off Toyotas Synergy Drive.
I believe Toyota has about 200+ patents on their Hybrid System
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Randall Halcomb 10:45PM (12/18/2005)
It is developed seperately and is not necessarily a copy or licensed from Toyota. I think that is key, despite the similarities.
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r.yo 10:45PM (12/18/2005)
toyota is the undisputed KING of PR spin, as post #3 shows. The ford and toyota hybrid systems are entirely unique and were developed separately. However, toyota made it to the patent office first, and since the ford system had conceptual similarities (including such basic ideas as an "electric motor working with an ic engine to power a vehicle"), the two companies entered into a patent licensing agreement. ford licensed some of toyota's hybrid patents, toyota licensed some of ford's diesel engine patents. licensing merely means both companies acknowledge that their systems have some similarities to previously patented concepts, and this allows production & development to continue without the threat of intellecutal property litigation. the systems were still 100% unique.
it's funny... after every published hybrid escape review where the author implies the ford system is merely a re-branded prius system, you will see a strongly worded letter to the editor from ford a few days later, attempting to set the record straight (last one I saw was in USA Today).
the reason toyota should be commended for their mastery of media management is that patent licensing agreements happen all the time in many industries. toyota, however, saw an opportunity, and when this agreement was reached, they issued a press release announcing ford was licensing their hybrid technology, and then they just sat back and watched the misinterpretations begin. oh, they're good.
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Randall Halcomb 10:45PM (12/18/2005)
#5,
I will openly apologize if you feel like I am calling the Ford system a re-branded synergy system.
I do acknowledge that they are different however, and I understand your frustration with the media in this respect.
the development folks at Ford put serious time to create this system, and while conceptually similar it is different than Toyota's.
Just because Mercedes has lineage to the original gasoline I.C.E., we don't say that every gasoline I.C. that is conceptually similar is a 'copy' of the original design. Hybrid technology can be thought of the same way.
Thanks for your opinion, however. More people need to be as vocal about this issue as you are.
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md 10:45PM (12/18/2005)
Would this system fit in a Focus, or would ford have to bring back a countour/mondeo based car in order to implement it into a compact vehicle?
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tom 10:45PM (12/18/2005)
No this system probably would not fit in a Focus, BUT they will be releasing the new Ford Fusion and Mercury Milan which are smaller then the Five Hundred/Montego yet bigger then the Focus. They go on sale in about a month. A hybrid Fusion and Milan should appear about a year later along with an All Wheel Drive version.
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Ben 10:45PM (12/18/2005)
I'm pretty sure that's an Atkinson-cycle engine in there, not an Aktinson.
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mephit 10:45PM (12/18/2005)
They've fixed the AC in the '06 model? WTF? What about us '05 buyers, are we just left out in the cold then?
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md 10:45PM (12/18/2005)
Mephit, i hate to break it to you, but thats the way it works. early releases of models will have more bugs and shortcomings that in a lot of cases are corrected over the years. if you choose to buy a car just after it comes out, you are subjecting yourself to these things.
I forgot about the Fusion hybrid. they anounced that one a while back. i hope for Ford's sake it is more effiecient than the accord and upcoming camry hybrids.
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Mark Sumner 10:45PM (12/18/2005)
A Question For Ford:
When you guys get your chance to talk with Ford's hybrid folks, be sure to ask them about the idea of a plug-in hybrid. The system that they've developed seems easily adapatable to this idea.
Toyota has said that they won't consider plug-ins in the immediate future because they're afraid the marketing would be confusing -- after all, they've just gotten it through people's heads that you -don't- have to plug in a hybrid.
I'd love to see Ford steal a march on the competition and add this option. I have 30 mile commute each day. If I could find a vehicle that would move even part of this commute to the electric grid, I'd buy it in a heartbeat.
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Adam 10:45PM (12/18/2005)
I'd like to know what the gas mileage is on this if you take off regenerative braking, and compare that to a car using just that aktinson engine.
The scheme they are using seems extrememly inefficient. Gas engine to generator to batteries to motor to wheels? Why not just engine to wheels?
If I was making a hybrid, I would just use the motor for regenerative braking, and then acceleration from stops. Anything above 30mph and the motor cuts off. Anything below 30mph and the engine is cut to partial power. Both the engine and the motor would direct drive the wheels, and the engine would never be charging the batteries.
This cycle of engine - generator - batteries - motor - wheels is EXTREMELY innefficient.
PS-I'm not just a moron, I'm going to be a sophomore mechanical engineering major this fall.
I can see how regenerative braking would help, but all this other stuff they have seems to just be taking away from fuel economy.
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Adam 10:45PM (12/18/2005)
Ha, I am a moron. I meant I'm going to be a junior ME major... haha.
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Gary 10:45PM (12/18/2005)
While I'm an EE, it's been 21 years since My Electric Machinery class, so can someone please help with this part:
"In this mode, the generator is producing energy from the gasoline engines output. This energy can be used to charge the batteries or POWER THE TRACTION MOTER." (emphasis added)
Why would you want to have the engine run the generator to power the motor, rather than sending the engine's power directly to the wheels? Are the electrical and conversion losses through the generator/motor less than what would be lost through the transmission?
Oh, and Mephit? You aren't left out in the cold; you're left out in the heat. [wag]
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md 10:45PM (12/18/2005)
Hmm...
Maybe the key is that the generator also holds the function of charging the batteries while the IC engine is in operation. Possibly the regenerative braking does not provide enough recycled energy or maybe the batteries run out faster due to the fact that the vehicle is heavier than say a prius, so the motor must work harder in order to move the vehicle, thus using up more stored energy.
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Adam 10:45PM (12/18/2005)
Charging the batteries for the motor with the engine is terribly innefficient.
With regenerative braking you could get back up to the same speed as before you stopped, if it was 100% efficient. It'd be more like 50 percent efficient, if even that.
The ONLY benefit of hybrids, fuel wise, is that they have regenerative braking, that's it.
Anything else they do is not efficient. Because the most efficient way to use the gas is to go engine -> wheels.
The reason these do well is that they have smaller, more efficient engines, and are usually lighter and more aerodynamic, though that doesn't apply here. But how would a car with just this engine do? as opposed to a car with all the other crud in it. Then compare the price difference, how many years does it take to recoup the cost?
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Corey Allen 10:45PM (12/18/2005)
I'm not so sure the gas motor to generator would really be that inefficient as you could run the gas motor at its optimum rpm at all times. I realize you'd loss potential moving energy as heat but I wonder how much difference there really would be. As well what about using a turbine to run the generator with its size to weight ratio and excellent fuel usage at a given consent rpm. I think this would make for a good combo although $$$ one.
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bill 10:45PM (12/18/2005)
Adam - your lack of understanding of the benefits of hybrid technology is made more evident by your lack of understanding of physics in general.
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Adam 10:45PM (12/18/2005)
Um... that's why I have a 3.58 GPA in ME right?
I haven't gone over this in a while, so I forget every one of these percentages, but lets be generous and say that each one is 70% efficient.
The generator is 70% efficient at making electricity, then the battery is 70% efficient at storing it, then the motor is 70% efficient at making it back into kinetic, then the gearing is say 80% efficient from motor to wheels. So, what's the overall efficiency here? .7 * .7 *.7 *.8 = 27.4% I didn't even add in planetary gearing from the engine to the generator, and 70% is an overestimate on some of the ones I did do. If you just went engine to wheels, that's going to just have the loss of the transmission in there. Ok, so you have your engine not running at optimal efficiency, so use a CVT, or some other transmission the try and keep it at the right RPM. There are much easier and cheaper solutions to this problem, they just don't include the regenerative braking aspect. But loosing 73% of the energy by charging batteries with a gas engine for an electric motor to use them is a pointless waste.
Now tell me what my lack of understanding is Mr. Big Words?
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