Hybrid Idea

[expat]

OK a crazy idea, so shoot me down on this:

How about a Hybrid as a conventional front wheel drive car, but with an electric motor that could drive the back wheels!
The battery pack could be charged by the engine or at home/Charging station.
Advantages:
In stop and go traffic or in City centers* the electric could be used on it's own.
On the Hwy (or as a back-up if batteries are down) the Gas/Diesel engine would be used on it's own.
In an emergency both motors would provide 4 wheel drive.
Battery pack could vary in size to suit owners needs.
Both systems would be largely independent (less complication)

What do you think?

*Some inner cities want to phase out emitting vehicles for reasons of Air quality.

 

[rcy]

The Lexus RX400h and the RX450h already have the rear wheels being driven electrically only.

 

[Kiwi_ME]

The Prius type of full-hybrid transaxles already depend on having two motors - the second smaller one to facilitate the engine's CVT function. However the larger motor which is the primary traction motor could just as easily have been attached to the rear axle instead. And having two motors at the back simply would be an alternative to requiring a differential.

At this stage of the game pretty much every hybrid scenario is being studied. I would guess that patents are the biggest roadblock to the best choices.

 

[flacoman]

My idea revolves around a turbo-diesel power plant with two stage expansion. First hot-side spins a generator for electric power or batteries ,second stage pressurizes the intake charge. Heck you could even directly return the energy with a planetary gearbox. Turbo compounding isn't new and Scania was flirting with it a few years back for their trucks . If you're scared of batteries and the metals and shock hazards, use hydrostatic drive and re-pressurize the accumulators with compressed air from whatever source you have. Should you want some extra scoot, dump in fresh fuel into the exhaust stroke and have afterburner mode ;-)With ceramic hot parts ,some of this has material that will handle the design environment.
Chew and discus all
Jorge
Chew and discuss

 

[Nick R]

My idea for a hybrid is fairly straightforward, very similar to the Volt. A small turbodiesel engine, 1-1.4L in displacement acts as a generator, and turns a generator, which charges a small bank of batteries for rapid acceleration and draw. Locomotive power is provided by two independed electric motors, one on each front wheel, each providing ~60HP. I think this would be an extremely efficient vehicle.

 

[expat]

I don't like the idea of Hub motors (unsprung weight apart from anything else) I think of Two motors housed in one casing, mounted to the vehicle frame, with a CV jointed shaft to each drive wheel.
I don't think you need anything like two 60hp motors!!
I see electric power to be used for low speed use via a planetary reduction gear, or as an acceleration boost in direct drive.
For higher speeds/longer distances it's still hard to beat a small Diesel.

 

[Nick R]

Originally Posted By: expat
I don't like the idea of Hub motors (unsprung weight apart from anything else) I think of Two motors housed in one casing, mounted to the vehicle frame, with a CV jointed shaft to each drive wheel.
I don't think you need anything like two 60hp motors!!
I see electric power to be used for low speed use via a planetary reduction gear, or as an acceleration boost in direct drive.
For higher speeds/longer distances it's still hard to beat a small Diesel.


Gearsets= added complexity and lowered efficiency. A CV Joint and driveshaft at MOST.

 

[CivicFan]

I think a fully electric car with a small IC engine as a charger for the batteries is the best solution. It will eliminate the need for a transmission and reduce the weight which can be used for increased efficiency or for more batteries. I think Audi is coming up with a production car like that and GM has been toying with the idea for some time now.

 

[nthach]

Originally Posted By: rudolphna
My idea for a hybrid is fairly straightforward, very similar to the Volt. A small turbodiesel engine, 1-1.4L in displacement acts as a generator, and turns a generator, which charges a small bank of batteries for rapid acceleration and draw. Locomotive power is provided by two independed electric motors, one on each front wheel, each providing ~60HP. I think this would be an extremely efficient vehicle.

That is being made currently somewhat in the form of a bus - an Orion VII with a BAE Systems drivetrain currently being used in San Francisco and New York. Here, a Cummins ISB engine similar to what Mopar offers in the Ram 2500/3500 is coupled to a generator which in turn drives a motor.
http://www.dcbusna.com/orion/0-867-1232397-1-892379-1-0-0-0-0-1-10595-584008-0-0-0-0-0-0-0.html
http://www.baesystems.com/ProductsServices/bae_prod_eis_hybridrive.html

 

[Kiwi_ME]

Originally Posted By: rudolphna
Gearsets= added complexity and lowered efficiency. A CV Joint and driveshaft at MOST.
Direct drive is not likely to be cost-effective and I doubt we will see much of that. You pay for a motor by frame size (=torque) and will get more value for money out of that (=HP) with a reduction gearset rather than limit RPM by wheel speed. The EV-1 and Tesla have a single optimized reduction, as does the Prius on it's traction motor.

 

[ekpolk]

Originally Posted By: rcy
The Lexus RX400h and the RX450h already have the rear wheels being driven electrically only.


Highlander Hybrid too.

 

[XS650]

Originally Posted By: Kiwi_ME
Originally Posted By: rudolphna
Gearsets= added complexity and lowered efficiency. A CV Joint and driveshaft at MOST.
Direct drive is not likely to be cost-effective and I doubt we will see much of that. You pay for a motor by frame size (=torque) and will get more value for money out of that (=HP) with a reduction gearset rather than limit RPM by wheel speed. The EV-1 and Tesla have a single optimized reduction, as does the Prius on it's traction motor.


Bingo, give than man a prize off of the top shelf.

 

[Gary Allan]

Use as small a diesel engine as possible and use batteries only for peak shaving of load. Most cars wouldn't require more than 40hp to move them at highway speeds. Let the engine run full time if need be. Have it run at one fixed speed which should simplify the design. Have it shut off when batteries are fully charged.

That shouldn't require any of the bells and whistles the current offerings have.

 

[KrisZ]

You want simplicity, skip the whole battery and electric motor thing. Hydraulic hybrid is the way to go.

Small hydraylic pumps at two wheels act as hydraulic motor and brake. Small diesel engine would run at constant speed if additional pressure was required. You get almost all energy back into the tank from braking, there are no battery losses and cold performance issues.

 

[Kiwi_ME]

When you consider all those hybrid alternatives you very quickly arrive at why the Prius (and ilk) are such brilliant designs. They encompass load leveling with power buffering and regenerative braking - allowing the average load to be supplied from a spark-ignition IC engine that itself has been designed for efficiency over flexibility.

The cost savings of using a simple spark-ignition IC engine and lack of conventional (or belt-CVT) automatic transmission allows the use of two fairly-expensive permanent-magnet motors with all related electric power conversion hardware, computerized controls, and traction battery. All the mechanical power transmission requirements are realized in this mechanically-simple but perhaps somewhat electrically-complex package.

Sure, the same functional drive system could have been implemented with hydrostatics or even rubber bands but it's hard to beat the smoothness, reliability, and program-ability of servo motors in closed-loop control. Real or perceived initial product failures as a result of applying cheaper technologies would have been devastating for Toyota.

If that wasn't enough - each new generation of Prius has evolved in subtle ways for better efficiency that show an attention to detail previously unheard of in a consumer product. With much of the functionality software controlled, this is where the early design choices pay off.