I notice while driving my '07 TCH the Gas Motor (or ICE as you guys like to call it) shuts itself off and restarts quite frequently. Its made me curious and wonder if the engine relys on a conventional starter & the 12V battery, or if the ICE uses the traction motor to restart.

Another thing I know, is starting a gas engine requires more fuel than letting it idle, wouldn't forcing the ICE to restart repeatedly reduce mileage?

 

My theory is the engine is started by the electric motor MG2 in the transmission when you first start the car. If needed when driving in the EV mode could be a short burst from the traction battery to the motor would quickly start the engine. This would help with the smooth transition from EV to the ICE running.

The 12 volt battery handles all the 12 volt jobs on the car, ECU, instrument panel, all the fans, head and tail lights. It does not have anything to do with spinning the engine to start, but does power the ECU which instructs the traction battery to do the starting.

Actually the new engine has such low friction could be that the power split device or PSD could also kick start the engine with the cars momentum. This could be the reason we feel a slight nudge when this occurs.

The new '12 hybrid uses ultra-fine injectors and improved low friction rings to work even better as a lean burn engine. The engine stays warm so once it kicks back in, it's already going around 1500 rpm depending on your speed and back to propelling your car along.

 

Just guessing here, but I believe that when starting the ICE, it spins it up and then adds fuel to keep it going unlike a conventional ICE which when starting adds gas first so there is something there to keep it going, also a conventional ICE seems to rev a bit when first started and then go down to idle. These are little things, but they do add up.

 

I've noticed that if the heat or a/c is off, the ICE seems to stay off until the battery shows that it is almost drained (when the car is not moving). With the climate control on, it starts up and shuts off quite frequently.

 

Don't guess or theorize.
It starts off MG and traction battery, aka hybrid battery.
Here's one "must see"

 

This is exactly what I needed. No theories or guesses. This video answers ALOT of questions I had...

so I guess I dont have a conventional starter, nor a conventional alternator that runs off of belts or anything. Awesome, thanks!

 

Thanks ukrkoz for this great description and youtube web site describing the eCVT. I have known about the lifetime drive chain that drives the axles for years. This is the first time I have seen the rather good sized drive sprocket. The chain I understand also brings oil up from the bottom of the tranny case to help lube the CVT. I also heard a mention of a tranny oil pump, no doubt it includes lubing all the parts and bearings.

I know the CVT must lubricate good. When driving down the slow but fun grade east of Ruidoso 'at the last Indian walkover' just past the Old Road. I would slow my car to below 40 to get the engine to stop. The battery was at a 80% charge. Then I would move the gearshift lever to neutral. Now no engine or charge, but the steering and brakes and headlights still work fine. Many times I have coasted from 45 to 72 mph for the 16 miles and including a few miles in the town of Tularosa, NM. I did this 4 or 5 times in the '07 TCH and once in this new '12 XLE TCH. Any reason to use the brakes I would first move the lever to drive.

Probably not a good idea for others here to try this. I was wanting to see how far the car would coast in neutral. I did have to keep a eye on the traction battery watching to see if it would drain below 20%. When the car is in neutral the engine will not start till the lever is put back into drive.

I would love to see how many engineers it took to design the first Prius eCVT. That would have been back around 1993/94. They started testing the first Prius in '95, first sales in '97.

I wonder how long before a complete redo of the Prius similar to what Toyota did with the Camry.

 

There are two electric Motor Generators in the THC.
A tiny one called MG1 and a more powerful traction motor that drives the wheels called MG2.

MG1 is part of the constantly variable transmission. MG1 instantly reverses its roll to spin up the ICE when the THC master computer deems ICE is needed. When oil pressure is correct another computer injects gas and fires up ICE to deliver power.

All of this takes place faster than a human could ever think or manually control. I am backing out of the my garage and part way up a steep drive before the THC master commander beams the message to the engine compartment "More power Scotty"!

The THC has forty two computers designed to make a hybrid car happen while mastering your safety, comfort, and providing multimedia entertainment.

 

I'm almost sure they are alternators but toyota calls them generators and they do generate lots of AC volts. It's the inverter that changed the generated AC to DC, to charge the traction battery.

After seeing the youtube video it looks like the smaller MG1 slightly charges the traction battery all the time while driving, even though the readouts don't show it.

 

It uses MG1 to start and restart itself. However both MG1 and MG2 are both motors and generators. Here is a summary of what they do from the Oakridge report.

"The first MG (MG1) is geared to the engine and primarily acts as generator, but also provides power for speed control and engine starting. The second MG (MG2) is geared directly to the drive and acts as the traction motor but also can act as a generator for regenerative braking."