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Discussion Starter · #1 ·
Hey there!

I recently discovered this site and am inspired by the creativity and passion for fuel efficiency and savings. Basically, my idea for a backyard hybrid is inspired by BionX's "hybrid" system for bicycles. I want to just make it bigger and apply it to a vehicle. I should also not that while most hybrids seem to be focused on in town operation (with the engine turning off at lights, etc) mine is more of a rural or suburbanites hybrid in that it would deliver the most gains on the hiway.

The vehicle in question is a Jeep Cherokee. Not the best platform, I know, but my concept revolves around removing the transfer case, and transplanting an electric motor so that any added power happens after powertrain so it doesn't have to be modified and can function as if there were a strong tail wind, or it were going down a hill (which would help me avoid any Check Engine lights or confusion on the PCM's part). The ample cargo area in the back is also an appealing factor seeing as you could put a large but flat battery cell in the cargo area and still be able to use the cargo area. The vehicle would obviously not be used for off road, especially since there would be no more 4x4.

The entire concept is approached as humble one, designed to be cheap and simplistic, and to merely improve the vehicles fuel economy to that of, say a TDI Volkswagen or something. I would love to integrate the BionX torque sensing / matching function, its stand alone throttle, and its regenerative braking. Ideally, except for the extraneous wiring, the jeep could go back to its normal condition quickly and easily with a quick disconnect and removal of the motor and replacement of the transfer case and front drive shaft.

For those who aren't familiar with the BionX system, the torque sensing feature actually senses the input torque (through the rider's leg, into the crank of the bike) and depending on what you want, you can have the motor automatically match each stroke by 25, 50, 100 or 200%. It's the most effective way to get the most charge duration and is very smooth except for the "turbo lag" sensation (it takes half a second for the motor to kick in initially). There to be a setting at the controls of the driver that would be able to turn this function on and set the parameters. The torque sensor could be placed at the tail shaft of the transmission, before it goes into the electric motor (formerly the transfer case).

With the BionX system you can also sit on the seat, and move using just the throttle on the controller without moving your feat at all if you wanted too, and I thought this could be utilized for cruising situations, using the Jeeps cruise control to control the throttle of the electric engine, effectively fooling the jeep into thinking there is an enormous tail wind or that you're going down a steep hill, which causes the Jeep to lay off the gas pedal completely and idle for as long as it needs to (which in this case could be several hours on the open road). After doing some research, people have said their vehicles use between 0.84 and 1.80 liters of fuel per hour as they idle. With the vehicle going a speed of 100 km per hour on pure electric power as the engine idles, that equals any where from 130 to 280 mpg (US) depending on what the actual idle consumption of the Jeep would be.

A physics student posted some information he had gathered on the power needed to propel his car down the hiway at a steady 75mph. His information concluded he needed 15 Kilowatts (20 hp) on flat ground, and for a 6% grade, 45 Kilowatts (60 hp). His car was an 05 Jetta. The difference in the coefficient of drag between a Jetta and a Cherokee is about 66%. They actually weigh about the same (right around 3300 lbs). So that tells me that for my hybrid to work properly on the hiway I would need a motor capable of producing about 75 kilowatts of peak power.

The regenerative braking function could take its signal from the brake light sensor behind the brake pedal so that as soon as you touch your brakes, the motor is already helping you brake. The BionX system is calibrated so that initially it only does it a little bit, and slowly increases the braking power as you hold it down so there are no jerking feelings.

Last but not least, it would be charged (primarily) by plugging it into the wall.

Now that you've heard of my vision, what am I looking at for price for a smooth operating, torquey, 75 kilowatt motor with a battery cell that lasts about 6 hours on flat ground at cruising speed? And how would I adapt a motor to receive the 23 spline output shaft of my transmission, and connect to the rear drive shaft?

What complications might I encounter?
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