Homemade Hybrid

hybrid-repair
gasoline
fuel-economy

#1

I am wanting to make a homemade hybrid. I think there is a way to mate the turbine side of a turbo-charger to a prestolite dc generator (aircraft generator) and use it to power an aircraft dc starter motor connected to a rear wheel axle of a front wheel drive car. 8 motorcycle or small engine batteries can be connected in series to match dc voltage and a plug in charger can be purchased. What I don’t know is how many horse power can be generated assuming a 96V generator is used.


#2

Exhaust-driven turbochargers provide very little torque and extremely high RPMs. Even if you could get the generator to turn, it would be an extremely inefficient system, and you would end up using MORE gasoline due to exhaust restriction.


#3

In the power industry 4 pole generators run at 1800 rpm and 2 pole generators run at 3600 rpm. The limiting factor is to ensure 60 Hz. How much faster does a turbocharger spin? If it’s faster than 4000 rpm the generator would have to be connected to a reduction gear.

The amount of torque produced directly relates to power, so it sounds like the turbo-charger impulse turbine wheel and cups are too small. That would require a new blades and a new casing (possibly 2 sets of wheels). That means I’d need to know if there is enough room under a 93 ford taurus (cheap test car) to accommodate the right sized turbine. I’d like to know how many ft lbs of torque it produces.


#4

Figure the turbo to run at 10K - 15K RPM in normal operation. It would obviously slow down when connected to a generator, with or without reduction gearing. I don’t know how much torque is available, but you have to remember a turbo is designed to be an air pump, driven by air (exhaust).


#5

I agree with NYBo’s comments. Even the slightest drag from coked bushings will bog a turbocharger down, or cause it to quit completely, so one can imagine what it would do when a heavy load such as a DC generator is applied.


#6

Thanks guys. I went to some conversion tables (http://www.magtrol.com/support/motorpower_calc.htm) and found that a turbocharger theoretically rated at 10 ft/lbs is capable of providing 19 hp at 10,000 rpm. At 15000 it will provide 28.5 hp (14.19 and 28.29 Kw respectively). At 96V it will produce about 222 amps dc. Now I need to find an actual power curve.


#7

I don’t see how this could be more efficient than running the generator off the crankshaft. In fact, with the throttle closed and engine braking being used to slow down the car, there would be some regenerative energy capture with the crank-driven generator. A turbocharger would slow down very quickly with that load as soon as the throttle closed. And the use of a crank-driven generator is STILL an energy loser.


#8

Ok, at slow speeds the dc motor has to be driven from the battery. After the turbo speed is at least 1000 rpm the dc feed switches to the generator. Like we talked about before, the turbo may not start spinning the generator if it is at a dead stop. Therefore, a start switch might have to be added to the dc circuitry. Closing the start switch will cause the generator to motor which will start the turbine spinning.

Efficiency: the way turbos are currently configured is to add ram air to the engine intake using otherwise wasted energy. When design compressed air flow is met a dump (bypass) valve opens. By replacing the centrifugal compressor with a DC generator and using a DC motor to power a wheel the waste energy is transformed from making addition power to making the vehicle more efficient. A side benefit is that power is instantaneously available, via the battery. I’ve found the the maximum velocity the prestolite generator can spin at is 2700 rpm. Now I’ve got to figure out how to keep the generator from flying apart, as well as the wheel motor.

Another variable I have to find is exhaust flow. If the exhaust flow is too low without having a turbine-generator attached it won’t work. I might have to go to a high flow catalytic converter and muffler.


#9

FORGET to turbo stuff. Just concentrate on developing the regenerative braking part and you get 80% of what factory hybrids offer.


#10

I did. The Toyota model was originated by EPA labs in the 1980’s. I would prefer the newer EPA labs hybrid. http://www.epatechmatch.com/EPA/Patent/PatentList. Look for hydraulic hybrid.


#11

I chose to use Unison aircraft dc motor/generators, because the are designed for both military and civilian applications. All Unison aircraft dc motor/generators redline at 12500 rpm (see http://www.unisonindustries.com/ourproducts/apcsg.html). Therefore, an exhaust flow bypass valve will need to open around 11000 rpm and close at 8000 rpm. A redundant engine trip signal must be generated at 12000 rpm to ensure passenger safety. Exhaust flow bypass line needs to be sized sufficient to ensure TG speed does not continue to increase after the bypass valve opens.

The biggest hurtle is cost. Each rebuilt Unison DC M/G cost $2,500 and new Unison M/G’s cost $4,800. This doesn’t include the correct DC motor controller, wiring, machine shop and labor costs.

Feasibility: The above research indicates that is feasible to marry DC Electric Vehicle technology with an exhaust powered single stage turbocharger. Marrying the two technologies should nearly double the rated mpg, because of continuous DC motor torque supplied to one wheel. Other advantages are reduced gasoline engine wear, fast off the line acceleration (0-60 in 5 seconds), and the ability to transfer the DC system between similar vehicles, e.g. buying a new car. However payback (approximately $12000-16000) is only achievable for someone who currently drives a 30 mpg vehicle at least 25000 miles a year for 10 years, and gasoline prices remain above $3.50/gallon (8 years for 25 mpg owners, 5 years for 20 mpg owners etc.)