Prius Prime and the mg1/mg2 situation

Prius Prime is not a BEV. It is a PHEV. That parallel hybrid configuration requires MG1, MG2, and ICE coupling through the transaxle. You can't even vary the gear ratio otherwise. The details of how the hybrid transaxle works can be found in dedicated threads on this board. If you eliminated the ICE, then you would have a BEV and a whole different ball game.

 

Remarkably, from what I've seen so far, across all the generations, Toyota has never touched the tooth counts of the ring, sun, and planets in the PSD.

They have, however, kept tweaking the ratios between MG2 and the PSD ring, and between the PSD ring and the axles.

 

I can't wait for Prof. Kelly to school us on the Gen5 transmission. His hands on lectures are fascinating.

The thing I love about Toyota's design is the mechanical simplicity of it. Very few moving parts in the transmission compared to a 'normal' transmission. And the very reason the Toyota E-CVT is so reliable.

 

Patented Feb. 8, 1910.
Application filed November 5, 1908. Serial No. 461,204.
To all whom it may concern:
Be it known that I, JOHN GODFREY PARRY THOMAS, electrical engineer, a subject of the King of Great Britain, residing at The Vicarage, Holywell, in the county of Flint, England, have invented new and useful Improvements in Power Transmission, of which the following is a specification.
This invention relates to those electromechanical systems for the transmission of power, in which a prime motor and two dynamo electric machines are mechanically interconnected through three members of a gearing so that the speed of each machine is determined by the relative speeds of the remaining two; and the object of the invention is the provision of the requisite members and means of control for the production of a system which allows of a wide range of speed variation by the use of the dynamo electric machines first as generator and motor and afterward as motor and generator respectively, .... To this end the three machines are joined, according to the present invention, through the members of a double epicyclic gearing of the two-member type; the prime motor is arranged to drive the cage bearing the pinions on which planet wheels rotate ....​

Hard to make it small and efficient and practical in 1908, before high power transistors (or any transistors), or field-oriented control of permanent-magnet motors, or any computer to do those calculations in real time and make it all happen. Turned out to be a pretty cool idea though.

 

I am amazed that the enabling technology for the Prius power transfer was patented over 100 years go.

GB190410880A - Improvements in and relating to Transmitting Power Electrically and in Controlling the same. - Google Patents

 

If it hadn't been for computerized power controls - the multitude of near instantaneous power switching would have never been possible in Toyota's Prius - much less it's several iterations in other vehicles, which even was implemented with Ford. We owe that tech to Alex Severinski.;
The Hybrid Inventor Who Sued Toyota - And Won | WIRED
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Very interesting. The inventor died at age 42 breaking land speed records.

https://en.wikipedia.org/wiki/J._G._Parry-Thomas

 

That's interesting ... I hadn't read those three patents before, and I'm only partway through the second one now, but so far I'm kind of wondering exactly what tech it is that we owe him.

I mean, we owe a ton to all of the tech for high-speed, high-power switching and control that Parry Thomas had never dreamt of. Transistors, digital computing, and microprocessors were indispensable, for sure. A lot of people made valuable contributions there.

The math behind the Park and Clarke transforms for controlling a three-phase motor-generator, I'd like to think those folks got well rewarded for. They didn't get a settlement over the Prius for it, because Robert H. Park's was published in 1929, and Edith Clarke's (female geek yay!) in 1937/38. (First woman to be professionally employed as an electrical engineer in the United States.)

But Severinski doesn't seem to be talking much about that kind of stuff. I'm still sort of looking for what actual tech he is disclosing, beyond some general ideas about how to put motors and an engine in a hybrid car and how it would be nice to control them, with very little specific on technical ways he would do that.

The 7,104,347 patent that I'm just partway through is kind of an odd read, because the application was filed in March 2003, and it has an eight-page DISCUSSION OF THE PRIOR ART that reads like it's presenting a whole history of hybrid vehicle development as partial and unworkable or incomplete ideas and goes on in that vein for four dense pages without even mentioning the working one on the market that people had been driving for six years already. Finally, there is a passing mention of the “Prius” (yes, in scare quotes) in one paragraph at the bottom of the fourth page of the discussion, which then picks right back up for four more pages in the original vein as if describing something nobody has quite figured out yet.

He spends the last few pages of his prior art discussion on a suggestion that prior art has been too focused on choosing operating modes based on speed rather than the actual road load. He more than just suggests that, in column 13 line 8: "Neither Koide nor Schmidt-Brücken, nor any other reference of which the inventors are aware, recognizes that the desired vehicle operational mode should preferably be controlled in response to the vehicle's actual torque requirements, i.e., the road load" (I added the italics), and harps on it for two more pages, I think without mentioning once that it's already being done that way, thankyouverymuch, in a mass-produced car people have been driving for six years.

I guess I understand the strategy of not wanting to mention the “Prius” much in your prior-art discussion, if what you want to do with your patent is sue Toyota over the “Prius”. But it makes for a rather weird read.

Just that you say "controlled by a microprocessor" or "selected by a microprocessor" or "determined by a microprocessor" or "analyzed by a microprocessor" a whole heap of times in your patent doesn't mean you've said anything concrete about how the microprocessor is going to be doing that stuff. The mathy types like Park and Clarke and others contributed a ton of what's really going on there, but that stuff was long known (from before there even were microprocessors). And by 2003, I'd say, "hey, we could use a microprocessor to do that!" makes a perfect example of the kind of idea that "would occur to a person of ordinary skill in the art."

He does offer about this much of a tidbit to the "ok, so how would you, in fact, do it?" crowd:



which doesn't seem, to me, to have a lot of patentable aha! moments in it. It's pretty tied to his proposed mechanical design, which is less simple than Toyota's, with clutches and stuff, and has some numbers plucked out of the air. It looks sort of like the cocktail-napkin stage of design. Reminds me a little of Dilbert, somehow. Or of that old "problem-solving flowchart" that used to make the rounds.

I think I might have been a skeptical juror.

 

yea ... because they are so all-over-the-place available ... what with their $5,000 over MSRP markups

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Not so sure the rear motor in the 2023 AWD has generator capability integrated. Anyone able to confirm?

 

Doesn't take any extra parts to make a PM motor a generator. You just turn it, instead of having it turn you.

Same for the inverter that controls it: no extra transistors needed or anything, it's just down to the timing of when the firmware switches them on and off.

I'd be surprised if they decided to ignore the possibility of generating there, but I'm not sure. Don't they call that part "MGR"? I thought they did in some generations, anyway.

 

The size of the battery puts a limit on how much regen braking the front motor can provide. It isn't going to allow more braking force nor recovered energy. Having regen braking on the rear adds some additional control that might be worth it though.

 

Yes, I'm aware of how it works, thanks. The question is did they integrate that capability. I don't believe so, as all the reviews and literature simply refer to a "rear motor," not a motor generator. Also, on the animated flow diagram in the display, I did not see any arrows leading from the rear motor back to the battery, like it show on the front MGs. So, it appears they are not tapping that potential return energy. It probably over-complicates the system for the limited harvest from a 40 hp motor, I'm guessing.

 

Looks like it is a motor generator - this guy explains it at 12:32.

 

Video's a couple years old, so he might not be talking about Gen 5.

He calls it MGR, which was what I remembered too, but then didn't you say you'd seen it called only "rear motor" for Gen 5?

 

Yes, I did. But this guy seems very knowledgable, and was clear it was MGR. I think some of the reviewers called it just a "motor," and that's where I was unsure. I' still not totally sure, but it's looking like I was mistaken. Also he's indeed talking Gen 4, but the Gen 5 may be the same, only with 40hp!

 

Or it's been MGR in some other models or older generations, and it's a motor in Gen 5. I don't know.

I don't think Car Care Nut can have been talking about Gen 5 in a video from two years ago.

 

Quite right; it was gen 4. The question is did Toyo keep the system integrating the rear motor generator, or not? I'm wondering how they balance the MG braking effect between front and rear wheels? Does going to a bigger (40 HP) MG make that more challenging? There's still a lot of things we don't really know about the new AWD.

 

I wouldn't worry about any technical challenge; the ECU surely knows the characteristics of all the motors, it can calculate what braking force it wants from each one, and control the inverter to get the forces it calculates.

 

Toyota has been making hybrids with electric AWD since 2005-6 with the RX and Highlander. Pretty sure they've always called them MGR with them helping regen braking all that time. No reason as for them to stop doing so.