Power splitter function

When the ring gear (attached to MG2) turns forward the Planet Carrier (attached to the ICE) is stopped and the sun (attached to MG1) turns in reverse. Have a look at this site and run the sliders up and down to get the operation in you mind.
http://homepage.mac.com/inachan/prius/planet_e.html

 

I think the answer to your question is that there are two motor/generators. In the situation you mention (car moving with ICE off), the power comes from MG2 (which is connected to the drive shaft) and MG1 is left to spin freely and keep the ICE from turning. That's the way I understand it.

 

Russ:

Sun / planetary gears are weird, and they have been used a long time now in things like automatic transmissions. If you really stop to think about how they can possibly work, you'll get a migraine.

The person who invented them was either a genius or certifiably bonkers, maybe both. Just rest assured the PSD works well and requires no input from you.

If you really want to get a migraine, look at the pictures of a Zexel Torsen differential. All those little gears happily meshing together, the stuff of nightmares.

Jay

 

<div class='quotetop'>QUOTE(Russ Yost\";p=\"95889)</div>

OK, but my question amounted to " how is the planet carrier stopped, i.e., prevented from rotating?"
[/b][/quote]
the plantet carrier is connected to the ICE via a shafth that goes thru the sun gear. As it's stopped the planetary gears rotate on the shafts of the carrier and because the ring gear is turning the planets drive the sun gear the opposite direction.

 

<div class='quotetop'>QUOTE(Russ Yost\";p=\"95889)</div>

The PSD works like a differential. Have you ever had one drive wheel on the ice and found when you step on the gas that that wheel spins and the other does not? Now imagine that the spinning wheel is MG1 and the stationary one is the ICE. They just let MG1 spin freely (like a wheel on ice).

 

when the computer says start the ICE, MG1 is stopped and spun the same direction as the ring gear and that causes the planet carrier to rotate cranking over the ICE. I must admit that visulization of a planetary gear in operation is not easy as Jayman has said. But in operation it is simple in the extreme. Think of it this way 2 of the 3 gears have to rotate all the time the car is moving or the ICE is running. If the car is moving and the ICE is running all 3 gear sets are moving.

 

MG2 is the main drive motor and MG1 is the motor generator that charges the battery and supplies power for the inverter to charge the HV battery and power MG2 and the A/C if needed. It's also the motor that starts the ICE. MG2 also supplies power to the inverter to charge the battery in regen mode. When the ICE is stopped the drag is more than the total output of MG1 so it doesn't turn.

 

[font=Comic Sans MS:b25e0a1540]A similar thread is called "Hybrid Technology Demo" in the main forum.[/font:b25e0a1540]

 

<div class='quotetop'>QUOTE(Russ Yost\";p=\"95955)</div>

MG1 can be driven by either the ICE or MG2 depending if the ICE is running or not.

 

Actually, driving the car forward would push the engine forward. It's going in reverse where there's a potential danger to pushing the engine to turn backwards, and I would believe MG1 would be 'sent' to prevent that if needed.

But in drive under MG2, engine might turn, depending on engine friction and compression load, but if it moves, that's not an issue. I don't think it is likely to turn though at low speeds where MG2 is powered exclusively. Any faster and MG1 will be used.

 

it's not going to turn either direction as the planets will just spin on their shafts and turn the sun gear which trurns MG1. That's the beauty of a plantary gear set.

 

Russ:

Trust me on this. Unless you can find a working model of a sun/planetary gear set, say at a VoTech college or Engineering department of a large college, just accept that it works.

Ok?

If you just look at it on paper, you will swear on your own Mother that it's *impossible* and cannot work. The diagrams will give you a migraine. As I stated before, the person who invented it was either a certified genius or certifiably bonkers, probably both.

Once you play with a demonstration unit and see exactly how the planetary gears relate to the sun gear, then it will become clear.

And if you really want a nightmare or an aneurysm, look at a Torsen differential.

Jay

 

I used to rebuild overdrive units for manual transmissions and they used planetary gear sets. Forklifts use them as do HD trucks. Simple once you see them in operation and get your head around them. I agree with Jay drop around to a vocational school or a tranny shop and ask for a demo of a planetary gear set. The load that MG1 applies to the sun is what the ICE powers agains to assit in moving the car.