AutoblogGreen

Hey, you engineering types out there. I know that using 4 computer controlled wheel motors has advantages: (all at a price)

NORMAL ECONOMY MODE – Only one drive wheel receives power until slip occurs then power could be transferred as required. Drive timers could make sure that each wheel motor receives equal drive time (power) over the life of the vehicle maximizing motor life. Good for normal or slippery conditions on hard surfaces, rain, snow, sand, or even rock crawling where each wheel’s independently controlled torque and limited slip are paramount.

4X LOCK MODE – All wheels are locked to rotate at the same speed. Good for sticky surface conditions such as mud, hill climbing etc where spinning may help clean the treads and improve traction.

4X SKID-STEER MODE – Right wheels and Left wheels are locked together like a skid-steel loader. Forward the left wheels while reversing the right ones or visa-versa and you have ZERO TURN RADIOUS. There could be a small joystick that takes the place of the old manual shift knob or the steering wheel could lock dead-center and the top could separate into 2 control levers. THE ULTIMATE 4X4!!! Humm…. Military Applications in a HUMVEE Anyone?

CRAB PARALLEL PARK MODE – Wheel motors can be configured on “stalks” that can be rotated 90-deg. Come to a stop beside where you want to parallel park. Push a button to rotate the wheels 90-deg., and drive sideways into the parking spot.

BUT, I'm curious about un-sprung weight issues. Can you chime in on wheel motors vs. "drive train" motors/gearing as to how they might effect vehicle handling, motor longevity etc.?

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10 minute recharge sounds amazing!

Hopefully it is an affordable car, even though fuel savings are going to be huge with this.

And hopefully it is going to be available wordwide soon.

Governments and municipalities should provide 10-minute recharge stations everywhere for this. Including special parkings in city centers reserved exclusively for electric cars including free recharging.

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In hub motors do offer the advantages you mentioned, but they also have a lot of performance drawbacks.

Huge unsprung weight -- each wheel will weigh close to 100 pounds instead of 20-30. All of that inertia means that the responses of the suspension will be slow.

Weight at the far corners of the vehicle -- instead of a concentrated weight near the center of the car, a significant weight is placed at each far corner, increasing the polar moment of inertia. This slows response in turning. Imagine holding a bowling ball at arms length and spinning in a circle. Now imagine it with the bowling ball held tight to your chest.

Reduced reliability -- the total reliability of 4 motors is much less than one. One failed motor is a failure of the drivetrain, so 4 motors at 95% reliability present a system reliability of 0.95^4, or only 81%.

Increased weight -- if you want more power, scaling up one motor adds much less weight than adding additional motors. Differentials and driveshafts do not weight much compared to redundant motors and controllers.

Transmission implementation -- there is no way to change gears in all 4 motors without using 4 individual gearboxes. You could get around this by running a fixed ratio, but that would limit acceleration, top speed or both.

For sports cars and passenger cars, I don't think it's a good solution. Given the potential for sophisticated traction control and forward/reverse torque at individual wheels, it may have a future in off road applications.

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There is no real advantage to using just 1 of 4 motors for "economy". Unlike IC engines, electric motors are highly efficient over a wide power output range, so dividing power to 4 motors (or eight, as in the Eliica) has no significant efficiency penalty.

Another downside to using 4 wheel hub motors is that you need 4 motors and 4 controllers, costing more than a single larger motor and controller. However, for certain applications, the advantages may outweigh the additional cost.

Unsprung weight could be reduced by putting the motors (and even brakes) inboard and running a short drive shaft to the wheels.

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Peter, Chris M- Thank you for your insights. There may indeed be advantages to using wheel motors in low speed, off road or specialty vehicles. I can see your points in regards to passenger cars. K.I.S.S will also reduce vehicle weight, acquisition, maintenance and operating costs. I appreciate your help.

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Peter,

I did not fully understand your point about transmission. An electric motor normally would not require it due to an almost constant torque at all speeds. Can you clarify please?

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No problem. Electric motors do offer maximum torque at zero rpm and much higher rpm limits than gasoline engines, so with a reasonable range of speeds -- say 0-80mph -- you can get away with a fixed gear ratio.

If you multiply the motor torque by the gear ratio, you get the torque at the wheels. Wheel torque is proportional to the car's acceleration, so a shorter gear ratio will increase the car's rate of acceleration. However, it will also limit your top speed. So if you want both, you need multiple gears.

It's only an issue if you want both extreme acceleration and really high top speeds. I'm curious how ZAP plans on achieving 155mph and maintaining reasonable low end acceleration.

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Nice car, but it was already done in the late
1800s.
My new green car, the Vector, has twin gasoline engines and gets 80 MPG.
It is made from organic materials, and is totally recyclable.
One engine operates for super economy, and both for zero to 60 .
The new Vector concept car has plush Pecan interior panels
and the new "Vector" upholstery.

You can email for more info..
alfredschrader@aol.com

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The ZAP sounds like a very interesting car indeed. The only concern I have with all the electric vehicles is the cost of purchasing them. If we intend to curb the greenhouse effects, we must have these affordable for mainstream consumers not just the very affluent. Most cars and trucks are operated by middle and lower class I would guess, so this technology must be affordable or it is really just a high dollar toy.

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While I am all for any technology that involves less oil-not just less oil or coal dependency-and this car's hype sounds particularly user friendly, ultimately because so much of our country's electric power still comes from coal and oil industry I feel it is a less than ideal so called green solution to automobiles.

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wouldnt power plants have to work harder to meet the needs for these cars? wouldnt it take more energy and emissions to produce the electricity from the power plant and send it to the car? its all pollution, but now it all coming from the plants..

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i see all kinds of good and bad thing with a world full of these kind of cars.......first the good thing i see a big truck driving around with 3 to 5 people working serviceing these on business parking lots with services like recharges,wheel-motor replacement and maybe glass cleaning if your are lucky........this one truck income would be 100 to 150 millon dollars a year that on a fill-up $30.00 a recharge jest do the math......P.S. this is based on a 8 hour day..........some companies will own 100's of these trucks

well with every good thing come the bad things poeple will think way to try to get them for free.......like like jumper cables to get your charge out of your car maybe how to steal your wheel-motor and ect. ect. ect. you get what i am talking about....

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I'm curious how ZAP plans on achieving 155mph and maintaining reasonable low end acceleration

This is achived by the type of motor. It's a DC Servo motor. They are very different from any other type of motor. The controller vary the frequency and amplitude of pulses sent to the motor. The frequency controls the speed and the amplitude controls the acceleration. The initial starting is done with high amplitude low frequency pulses. As the motor starts to turn the amplitude begins to go down and the frequency increases. There is really no high end limit from an electronics standpoint, just the programmed limits to prevent damage to the motor bearings. You also have almost the same amount of power available almost instantly at standstill or at 100mph, the motor doesn't care what it's doing at the time, it always has the same available power, unlike conventional electric motors or combustion engines.

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-#11 is right, we need to develop better technology for electric plants, too. A lot of the pollution will switch over from the roads to the plants.
I think I know the difference, though; You can generate more energy from the same amount of fuel at the electric plant than in your car. That will at least cut down the amount of fuel we use, and make relatively less pollution.

If we would be consuming the same amount of fuel at the power plants, then the oil companies wouldn't care about getting rid of vehicles that use gas.

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14, you beat me to it. Can you tell me more?

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wouldnt it take more energy and emissions to produce the electricity from the power plant and send it to the car

No. The worst coal power plant producing electricity for an electric car will produce about one tenth the pollution of the cleanest gas powered car going the same distance.

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I would buy a car with a max speed of 70 mph, clumsy handling, so-so acceleration, average performance, and less interior room. I just want a car that doesn't use gas.

I know I'm not the only one desperate to get rid of this pollution. It's disgusting.

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I think the Zap is a great idea...however, it should have solar panels built into it to charge the vehicle during daylight non-use time, as to save on emmisions at the power plants....the sun offers tremendous power, and Im more inclined to lean towards that kind of product than this....one thing we can all agree on, is the fact that things are going to change.The enternal gas powered combustion engine will be a thing of the past in 50 years.

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Hats off to the inventors/engineers responsible for the batteries in this vehicle. That is where the promise for the future lies. As we search for cleaner energy formats, a major part of the solution is storage. I'd like more information on the batteries and types of charging systems.

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Gee: I realize this comment is far afield of the topic at hand, but, until the electric car is totally practical, read on. I know I am mature, and somewhat fuzzy headed. But, didn't the Presdient say that he wanted to get vehicles to use 20% less gasoline in 10 years. We (USA) can do that in no time at all. Some eyars ago, in New England and the Northtesat there was a product called gasahol, 10% ehtanol and 90% gasoline. It burned cooler, cleaner and didn't boost feul economy, but, it was 10% less gasoline we were using. Why not go with a 20%/80% mixture right noe? That would get right in with the Presdient and would START to ween us off of the imports. Wouldn't it?

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