Experimental Data / Correction

[Darnon]

The wheels are not directly connected to the engine. They are connected to the traction motor.

That's not entirely true; there's no mechanism that physically disconnects the engine.

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[The Real Maverick]

That's not entirely true; there's no mechanism that physically disconnects the engine.

What's your beef?
Nothing I said was untrue.
Maybe re-read this thread.

 

[The Real Maverick]

Lets dive deeper.

COULD the wheels spin the engine.
Yes.

If the generator was held stationary, the rotational energy of the spinning wheels / traction motor would transmit to the engine forcing it to spin, like a traditional vehicle.

But it would stop being a CVT. It would be a fixed gear ratio. It could not vary to match the road conditions. It would probably be "fixed" in a too high of a gear ratio to be useful for braking.
Seems apparent the generator must be spinning AND the gas engine must be spinning at a pretty high rate.

The traditional way of thinking, have the wheels "push" the engine could be made to happen, (in theory, I'm not saying the Maverick can) but I think you'd be stuck in something like an overdrive ratio, not something you'd want going down a steep slope.

Does that make sense?

 

[wax87]

Longer!

And yeah this ain't for normal driving on streets - I'd probably be getting shot at.

Though, last night coming back from sunset pictures at the park with son - one 45 mph road with 2 mile stretch of very gentle decline, that's hard to hit all greens because it goes thru 3 cities that don't time the lights - I started off the red light behind several cars so kept in EV mode the entire way, was up to 50 in about 1/2 mile and probably could have hit the 2 mile mark still in EV but slow car in lane, and while going to next lane to go around hit the Go pedal just a tad too much, when it was down at bottom of battery available. ICE was about to come on for steep incline as always, but that's about my only stretch of long road nearby to attempt that.

freaking awesome LOL

 

[HeyBales]

That's not entirely true; there's no mechanism that physically disconnects the engine.

When in EV mode and displaying traction and generator motors' RPM, you see the only thing "disconnecting" the engine is the matching RPM spin that is maintained between them.
Then the engine is 0 rpm.

Wasn't it a Webster U video where he spun the traction motor and it indeed spun the engine shaft partially, but higher friction so I think the plantetary gear also spun partially spinning the generator motor.
He wasn't demonstrating what normally occurs, just showing what spun.
Seems like engine friction would be enough the system would just end up spinning the PG more, and if no generator motor engaged pushing against that, then it's freewheeling. Or generating electricity!

 

[Darnon]

Wasn't it a Webster U video where he spun the traction motor and it indeed spun the engine shaft partially, but higher friction so I think the plantetary gear also spun partially spinning the generator motor.

Exactly. There's no controlled clutch or some other element like a fluid coupling torque converter. So there is always a gear connection path between the eCVT outputs to the input shaft linked to the engine crankshaft. It just becomes a stationary element of the 3-way differential that the planetary gear functions as.

 

[HeyBales]

The wheels are not directly connected to the engine. They are connected to the traction motor.

Going downhill and you want to slow:

Wheels turn traction motor. Traction motor can "freewheel" basically neutral coast and do nothing; or a load can be put on the motor and it can generate power, which creates resistance. Negative torque, which is "drag" that slows you down. But that power has to go to the battery or somewhere else.

When the battery is full, the somewhere else is the power goes to the generator that now acts as a motor. The same thing in the same way it starts the engine. This "motor/generator" spins the engine. Without fuel. But not for 2 seconds like when "starting" it, but it spins it continuously, for as long as it takes.

The generator has some mechanical resistance but the engine has a lot more. A lot more moving parts. Plus suction of air and/or compression of air, which creates the "work" for the generator to do to "use up" the excessive wattage.

I've not dug into the 2.5 engine enough to know - does ITCV or whatever it is have variable valve timing to even increase inefficiency of engine when more resistance needed?

 

[The Real Maverick]

I have limited reading in that area too.

Lots of people say the slowing comes from the engine compressing air.

A few say the slowing comes from the engine pulling (sucking) against closed valves.

Same net effect, I suppose.

 

[AVC]

Yeah, the fantastic Weber teardown of the HF35 (and representative of the HF45) show that the Gen Motor, Traction Motor and ICE are all mechanically directly coupled via the planetary set. Yes?

The Gen Motor plays a large part as a motor to manipulate the planetary set, providing effective gear ratios and allowing the ICE to be stopped completely, run at various RPM and torque values, or possibly, as compression dynamic braking on hills.

In generator/alternator mode, the Gen Motor spins but would only produce current (or power) when there is a load presented to it; e.g a charging battery, and/or indirect electrical loads, like the traction motor, 12v inverter, etc.

In any case, only an electrical load could dissipate excess electrical energy from the Gen Motor. The ICE can't provide that.

Don't think the Traction Motor is designed for extended dynamic braking either-- dissipating rather huge amounts of shorted stator current/energy, in that scenario.

Last, there is strictly no "wasted energy" in that scenario; primarily wasted opportunity to recover energy.

 

[dochawk]

Low-50's MPH on flat ground is pretty comfortably sustainable.

While experimenting with the adaptive cruise control on the freeway today, I was startled to see it go to electric at 58 approaching the peak of a flyover (followed by "charge") to control downhill speed, but I expected that part).

 

[Darnon]

While experimenting with the adaptive cruise control on the freeway today, I was startled to see it go to electric at 58 approaching the peak of a flyover (followed by "charge") to control downhill speed, but I expected that part).

Yes, it can function in electric drive albeit requiring some help such as being downhill (due to aero/limited power) up to something like the high-70/low-80's MPH. Past a certain point the traction motor's RPM is too high (well over 10k RPM) for the variable frequency drive that is the motor controller to keep up with.

 

[The Real Maverick]

Don't think the Traction Motor is designed for extended dynamic braking either-- dissipating rather huge amounts of shorted stator current/energy,

Don't know why you'd think it would be "shorted". That would only happen when/if you pressed the go pedal with your wheels chocked. In that case, there is motor stall protection. It's very hard to climb over a curb with your wheels pressed upon it. You normally need a "rolling start" first.

But yes, the motor IS designed for continuous regen, just as much as it is designed for continuous assist. Try some 15 mile long grades in Colorado or California some time.

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