Dualfuel, Am I right in reading your reply as two seperate power units, one at each end ? If so I think that guest@@ has something different in mind. I see it as two motors driving the different parts of one gear box. Guest@, am I right on this ? regards dva
Location: Yorks,England | Registered: 30 June 2001
If one was to find a 1955 to 1961 Buick, Cadillac and the odd Chevy, you would find it is powered using a "Turbine Transmission"...essentially a variable stator torgue convertor. By 1959, they had up to three of these convertors piggybacked to transfer the power.
Strangest feeling putting your foot to the floor, the engine reving to about 3,500 RPMs and the car catching up to the engine. No shifting, just solid acceleration.
Placing the car into low just locked the stators in full fine position and a off-set idler gave you reverse. The whole thing must have wieghed over 400 Lbs. was very inefficient and produced enough heat to fry eggs but it was indeed a true variable ratio transmission. To those interested, check the junkers for a late 50s or early 60s GM with a unigue shifter pattern:
P-N-D-L-R
Oh another thing...they leaked like they had been mugged. (Whale oil if I remember correctly)
Bill
Nothing is new...just remembered div.
Location: Manotick, Ontario Canada | Registered: 02 July 2002
quote:Originally posted by guest@@: There is a neat way to produce a variable speed transmission that uses planetary gears the same kind as in an automaatic transmission. The differance is that there are no shift points in this transmission. It can be done using two power sources One source turns the planetary carrier and the other source turns the sun gear. By keeping one source at a constant rpm and varing the rpm of the other we get a variable gear ratio effect. Now tell me it's been done. If not then full royalties to guest@@.cyber space
Sounds like differential action to me.
New Process transfer cases has a planetary gearset which acts like a center differential.
Using an open differential, one can place an electrical motor/generator on one output shaft and the drive output to the other shaft...and there you'd have a CVT and Hybrid drive in one simple unit!
Masochist to Sadist: "Hurt me." Sadist to Masochist: "No."
With the differential gear...I suppose in this case, an Intergrating gear...you do away with a clutch or torque converter: for any input engine speed X, the Differential/CVT/Hybrid drive has an output spectrum of speed gear ratios 0 to 2X, inclusive.
One only need to include a reverse gear
Masochist to Sadist: "Hurt me." Sadist to Masochist: "No."
You got the ratio right, though. Ring dia/sun dia + 1 = ratio for this arrangement.
I think they used an arrangement similar to this for variable ratio in a tank steering mechanism years ago. There was some kind of popular science article, I want to say.
Where this MIGHT have some application is in high torque applications. Current belt technology CVT's are quite limited in torque capacity. Rather than thinking about stopping, resisting, or freewheeling an element, think about changing the ratios of the speed. That DOESN'T neccesarily mean that energy has to be disipated.
For example, you could attach the ring gear to the drive wheels, the planet carrier to the engine, and the sun gear to the output of a conventional cvt transmission (or maybe even some kind of variable ratio hydraulic motor based on variable displacement) with the input of that CVT driven off the engine.
Now if you have 4:1 step up in the CVT, and the engine driving the carrier (in the same direction) the ring gear will remain locked.
As you slow the CVT, the ring gear will start to move faster. Once the CVT output (sun) stops turning, the system will act as a speed increaser - to the max ratio of 4:1
In this instance, the planetary system truly is acting like a mechanical transistor. Current is analagous to torque in a mechanical system. Transistors are current devices; The current in the output is equal to the gain of the transistor times the current at the input - with some limitations, of course. In this case, the gear ratio of the system would be related to the gain of the transisistor.
I know the RPM theory works, but I didn't do a free body diagram to see if the gain vs ratio analogy is correct - but it seems like it ought to be.
Eric K
Location: Saginaw, MI, USA | Registered: 30 January 2002
since stuff in ~=~ stuff out, we're just using the gearing as a torque amplifier; The work we put in between the slave and the motor is still there - the trick is how we generate the control torque.
Using a servo slave makes some sense, BUT I believe there's some electircal input to them. That's where the rest of the input energy is coming from.
I'm a little fuzzy on how servos work, but the energy has to come from somewhere, and if the input torque of the servo is nil, there must be some electrical energy going in to stick into the gearbox.
Power steering systems sap energy off the engine through the pump to generate the force to turn the wheels.
Eric K
Location: Saginaw, MI, USA | Registered: 30 January 2002
