Transparent plug-in hybrid retrofit for any car

http://mtsunews.com/wheel-hub-retrofit-update/

by rocky1138 • 14 years ago

68 54 14 years ago

pilom2• 14 years ago

Should be "any front-wheel drive car." It looks to me that they replace the rear axle with 2 electric motors (one on each side). I don't think they could install this on a car with powered rear wheels.

apinstein• 14 years ago

In the video he said it should work on 99% of cars. The motor goes on the wheel hub; it should be able to go on a wheel powered by an axle, too.

To me it is the same idea as the electric bike retrofit kits by Bionx.

fein• 14 years ago

I'm actually more concerned with how they've changed the design for rear drum brakes vs. rear disc brakes.

If I recall, that model Accord wagon had rear drum brakes.

edit: yep, it does have rear drums. I'm VERY curious to see how they intend to make this work for disc brakes, especially when the calipers have to wrap around that huge assembly.

The idea of rolling down the road and having a few magnets come flying off also scares the daylights out of me.

yello_downunder3• 14 years ago

I don't see how the design could be adapted to disc brakes. The majority of vehicles sold have drum brakes on the rear, probably close to the 90% figure the person in the video mentions. Furthermore, cars with disc brakes on the back often have a cheaper trim version equipped with drum brakes, so reverting these back to drum brakes would not be overly difficult - swap out the mechanical bits and adjust the brake bias.

eslachance• 14 years ago

This is awesome, except for one thing. As with all hybrid kits, you lose trunk space. Unfortunately, if I can't fit my groceries as well as the stroller for my daughter, it's out of the question. Obviously not everyone requires this, but how many commuters do you think never need the trunk space?

These batteries and controllers need to find another place. On the roof of the car, perhaps, unless you're an outdoor sports person and need racks for bikes or a kayak?

antidoh• 14 years ago

Maybe the batteries can be molded/fitted into body cavities.

Maybe one day the frame can be made out of batteries.

FelixP• 14 years ago

They don't show any photos, but I wouldn't be surprised if the batteries don't occupy the entire trunk, especially on the production model. Obviously this would also be dependent on the size of the original vehicle as well.

liberatus• 14 years ago

FWIW 4:22 of the video shows the trunk. It ain't small.

veemjeem• 14 years ago

The video mentions that the production ready kit will be about the size of an airplane carry-on bag. I think for most cars it's possible to fit a roller carry-on bag, a stroller, and groceries with ample room leftover.

ars5• 14 years ago

That depends on how many kids you have, and how far away the grocery store is (i.e. how much you buy each time you go).

rejuvenile• 14 years ago

I wonder what the efficiency numbers are. The retrofit will add weight to the car, but won't remove any in the form of a lighter engine. There is also no regenerative breaking, and presumably no way to disengage the engine to run purely on electric power. I also wonder, speculatively, if the power assist will interact degenerately with the existing automatic transmission--perhaps running the car in a less than optimally efficient gear.

tocomment6• 14 years ago

Actually I don't see why they can't put regenerative braking in. The motors double as generators and they already have a connection running to the battery. And the motors are right next to the brakes so they could easily detect when the brakes come on.

Anyone know?

pdonis3• 14 years ago

To do regenerative braking the motors have to know when you're braking. That means hooking into the car's controls to detect when the brake pedal is pressed. It also means preventing the normal mechanical brakes from engaging while regenerative braking is being done. And it means being able to engage the mechanical brakes if the batteries can't accept incoming energy fast enough. All this is a highly non-trivial controls problem, which requires close integration with the car's control computers. I don't see how that can be done with a retrofit.

tocomment6• 14 years ago

Also I don't see why you can't put the engine in neutral and drive with these motors (I guess you'd need a separate throttle though?)

rocky11383• 14 years ago

We don't have numbers, so this is all speculation. Still, I think we can agree it's a neat idea that definitely deserves exploration.

With regards tot he transmission question: my car (and many others) allow me to select the gear even though it has an automatic transmission. In my car it's called Autostick, other cars it will be something else; sportshift maybe.

In this way, I can ensure the gear will be optimal for gasoline consumption.

Also, perhaps in the future, a model can be made to incorporate regenerative breaking.

adjwilli• 14 years ago

Yeah, they say it gets between 50 and 100% better gas milage, but are those "savings" spent at the electrical outlet?

altcognito• 14 years ago

http://www.scientificamerican.com/article.cfm?id=electric-ca...

Depending on the efficiency of the implementation I'm sure (as well whether or not this is a valid study at all), but it seems that electric cars are able to do it significantly cheaper than gas. So those savings are probably not spend at the electrical outlet.

polshaw• 14 years ago

>perhaps running the car in a less than optimally efficient gear.

A properly designed solution would enable the opposite; keeping the car in an optimal gear for longer. A hybrid works best when the batteries run where they have the greatest advantage against the fuel.

3amOpsGuy• 14 years ago

Is there potentially a major efficiency issue here, through adding rotational mass in such quantity?

yello_downunder3• 14 years ago

The design decreases the efficiency of the car in total, through increase in weight, increase in mass and probably a few other things we haven't thought of. It makes up for it by allowing you to replace gasoline with electricity, which is much cheaper.

Less efficient, much cheaper, and hopefully less environmentally harmful.

I like what this solution offers - a chance for someone like me who will probably never buy a new car to easily modify an older car to run at least partially off electricity.

tocomment6• 14 years ago

Is there anyway someone could offer natural gas conversions for around this same price? That would also give you a huge savings (possibly comparable to this).

yello_downunder3• 14 years ago

It is unlikely that a natural gas conversion could be done for this price. The tanks to hold natural gas are quite expensive and I doubt we will find a significantly better way to build a high pressure tank than we already know about.

Then you have the issue about a filling station.

Then considering taxes on fuel are nearing 50% of fuel cost, you're right around where this conversion gets you. (I don't know if NG at the pump would be taxed)

Electric solutions work around the issue of fuel cost and filling locations nicely. Electricity is cheap and basically available in every garage. If you have a garage. Having a hybrid electric works around the issues of limited range and cold weather.

tocomment6• 14 years ago

I'm just thinking people would fill up at home. If nothing else use it for commuting. Most Americans already have a natural gas line coming into their house.

So charging stations wouldn't be necessary and taxes wouldn't be an issue either.

ars5• 14 years ago

In the US, Utah and Oklahoma have a lot of natural gas cars, and kits are easily and commonly available everywhere.

So if you are looking for prices, check companies located there.

robomartin• 14 years ago

Another fine example of an IMPLEMENTATION, not an INVENTION that should not receive any patents whatsoever.

Good work, of course, but, if you tasked any capable team of engineers to build a DC brushless motor as a retrofit into a car wheel this is what you would get. In fact, there are thousands of teams all over the world that could do this inside of six to twelve months with equal results.

lloeki4• 14 years ago

This is probably already patented in some way by Peugeot since that's (almost) how their 'hybrid4' (diesel+electric) work. The engine is not in the wheels but that's really not a stretch to place them there. I would be surprised it they did not try it.

[0] http://carscoop.blogspot.com/2010/08/new-peugeot-3008-hybrid...

Lagged2Death2• 14 years ago

Putting the motor in the wheels must produce a hefty increase in rotating mass and in un-sprung mass, both undesirable. It's necessary in the case of a retrofit, but in a from-scratch design I doubt an automotive engineer would try this.

infinitex• 14 years ago

Invention? In-wheel electric motors have been around for over a century? Using them for electric cars? That is mostly what they were used for.

http://en.wikipedia.org/wiki/Wheel_hub_motor

http://en.ekopedia.org/Wheel_motor

This company is doing something similar:

http://www.proteanelectric.com/

Let the law suits begin...

jhaglund• 14 years ago

I am not an engineer, but seems a retrofit like this adds un-sprung weight which increases wear and changes handling.

How about put the motors in a new differential? It'd take a larger casing, but you could apply the electric torque to each wheel too.

lloeki4• 14 years ago

You're just concerned about unsprung weight? What about the now positive torque applied to those wheels? That's the whole basis of how ESP works: applying a counter-force to a wheel in order to balance the car thanks to the torque generated around the yaw axis, so how does each motor knows what force to apply so as not to actually throw the vehicle off balance?

Think RWD cars. Floor it on a curve and you can go into a tailspin. But RWD cars are designed as having power on the rear while FWD cars have not, so the effect could be much more dramatic with much less force.

It's not that complex to solve... as long as you have access to the various sensors (Hall, inertia... if any) and actual decisions of the ECU, and design data (i.e everything the manufacturer has), but piggybacking on it is quite an endeavor. And it has to be done for each car model since they all differ dynamically and in hardware.

rocky11383• 14 years ago

One assumes that drivers will need to drive with ESP off after the retrofit.

stcredzero• 14 years ago

When I lived in Houston, I would've loved to see a hybrid retrofit of the type the original Honda Insight had -- a motor/flywheel. That could have turned my old biodiesel Mercedes into an acceptable hurricane emergency diesel power generator.

ck2• 14 years ago

My electric bicycle wheel works the same way.

Electric motors are great at low speed torque which is why it helps the gas milage so much with city driving. I bet it also can take a chunk out of the 0-60 time.

The next step is to add power regeneration during braking.

If this is practical, I am sure the big car manufacturers will just do an end-run around any patent with their own tweaks and then it will just be a lawsuit battle.

waivej• 14 years ago

It seems like an excellent project to work on.

Hybrids do well on gasoline because they have efficient undersized engines combined with light weight and excellent aerodynamics. This retrofit wouldn't change any of those things so I doubt it would have the claimed mpg benefit on a long drive. With a big battery pack, I could see it boosting MPG in city driving but it doesn't have gearing to use the motors at high speeds like highway driving. The big battery pack hurts city driving because you need to accelerate and decelerate that added mass.

It reminds me of similar retrofits that might be comparable and easier:

1) Replace the alternator (or AC) with a small 6-10hp motor. This is like a DIY version of the Honda IMA. I think GM was promoting something like this. You're limited by the power a belt can transmit, but it does go through the transmission and allows easy stop/start of the engine (ex: at a traffic light).

2) Remove the rear drive-shaft from a 4WD like a truck and attach a motor to the differential. This is also somewhat easy and a truck is better equipped for carrying batteries. There was a Jeep design that did this. Stay in "4wd" without applying power to the motor and it's like a front wheel drive. The downside is that the motor isn't geared so it's only good for one speed range (perhaps low end torque).

Unfortunately, both designs are just mild hybrids. To really go far enough with the motor you need lots of batteries. For example, the 80lb NiMH pack in my Insight can barely go a few miles. Regen makes sense but you lose a surprising amount of energy charging/discharging. I get the best gas mileage trying not to use the hybrid systems (even in city driving).

Transparent plug-in hybrid retrofit for any car

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