How Toyota Hybrid System Work Part 3 Hybrid Transmission
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- čas přidán 22. 10. 2020
- A Toyota Master Diagnostic Technician explains in simple terms how the inverter with converter assembly work in Toyota Hybrids.
In this brand new series I will go over all components of the hybrid system explaining their basic function in a simple way that's easy to understand. The theme of this series is simple but complicated.
The hybrid system in Toyota cars is super complicated and a marvel of engineering. In this series I try to keep things simple and light so Toyota Hybrid owners can see how their cars work.
I believe if you know how your car works you'll be able to utilize all it's features better and better understand your hybrid Toyota.
In this part of the series I will cover a very controversial subject. The hybrid transmission. Is it a CVT? eCVT? Or not? I'll explain how the transmission works including the electric motors MG1 and MG2. Also explain the components of the transmission. I'll also cover some maintenance items and mistakes that can happen like using CVT transmission fluid in your Hybrid transmission.
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That hybrid transmission is something special. When you look how simple it is, yet how flawlessly it performs and reliable it is, it's a really incredible piece of engineering. It's an insult to call it a CVT.
The transmission in these are amazing. I have driven an Auris hybrid for three years. They are so smooth, no gear change. Just amazing.
If you understand how it works, it's piece of art, it's breathtaking🥰🥰🥰
The thing that amazed me when I first learned how they worked is that the “magic” of these Toyota (and similar) hybrid systems isn’t mechanical, it’s electronic. They could have built that gearbox in the 1940’s if they wanted to, but the electronics to control it wouldn’t be feasible for another 50 years.
It's not an insult. It's a CVT 100%.
You just nailed it, it is an insult to call it CVT 👍
Toyota Hybrid systems are the pinnacle of system engineering.
I’ve been running a Yaris hybrid for a few years. Toyota use the term eCVT, because the gear ratio between the engine and the drive shaft is continuously variable, with it being electronically controlled via MG1. The ratio between MG2 (the traction motor/generator) is fixed at about 2:1. Both MG1 & 2 are variable frequency 3-phase motor/alternators.
Under acceleration, it can run the engine at constant speed, and via MG1 (by controlling the ac frequency) the effective ratio through the planetary set varies.
Worth noting that the use of the hybrid transmission makes it practical for the engine to run in a pseudo-Atkinson cycle, ideally at a fairly high speed or not at all, so as to optimise it’s thermal efficiency. There is some clever modern power electronics sitting on top of the mechanical bits in the hybrid, of course - 3 inverters and 2 convertors, handling 3 phase for the motors, HV dc, and the usual LV dc for all the odds & ends.
Seeing you discuss the Prius CVT made me want to share my thoughts on it.
What's called a planetary in the video is a differential, a differential is only planetary gears. Differentials are used in all cars to keep power applied to the drive wheels equally while turning corners. You may remember a time when one drive wheel slips in mud or snow and the other wheel goes nowhere.
So imagine a rear wheel drive car with one rear tire removed and pretend the car magically stays suspended. Then disconnect the hand brake from the wheel thats on the ground and leave it attached only to the floating brake hub.
Put the car in gear and try to drive it.
It won't go anywhere. Like in the snow, the hub will only just spin because of the differential.
Then start applying the hand brake to that hub, slowing it down, and the differential will put torque on the other wheel. The car will go and you can control the engine rpm and vehicle speed with the combined use of the gas pedal and the handbrake. If you put enough pressure on the handbrake so that the hub completely stops, the differential will pass all the power to the drive wheel.
That's the principle behind the Prius CVT.
Now replace the handbrake with a generator and instead of creating a lot of heat with the handbrake you create electricity with the generator. Increasing the field current of the generator produces more electricity and puts more of a load on the differential. Consequently more torque is applied to the other wheel. Of course, the electricity needs a place to go so put a motor directly on the other wheel, a battery to store fluctuations of demand, a computer to control the whole system, and you have a Prius!
No friction parts in the CVT since it's only basically a differential.
When slowing, the engine stops, the generator just spins with no field current, and the motor acts as a generator, charging the battery while slowing the car. Finally the brakes bring the car to a stop.
So the Prius actually has two differentials (planataries), one is the CVT and the other is just the usual one on the wheels. All elegantly put into the same shell with the motor and generator.
To recap, the CVT differential has three shafts, the engine, the generator, and the motor which is always connected directly to the usual wheel differential.
Couldn't be explained better 👍
Great explanation!
Well, a car's differential is functionally the same as the power split device, but its design and purpose is a little different. I prefer to call the function a "three-way transmission" and the difference, in the purpose of the device, is which of the three are considered to be inputs, or outputs.
The purpose of a conventional, two-way transmission is the alter the "input" spin rate - that is, the spin of the internal combustion engine, or ICE - relative to the "output" rate of the countershaft, or CS. Changing gears, whether in discrete steps (manual or automatic) or continuously (CVT) changes the gear ratio G in the equation: ICE=G*CS (or input=output).
A differential has one input, the countershaft. But it has two outputs, the two wheels W1 and W2. Most of the time W1 and W2 spin at the same rate, but they need to be different to drive around corners. So the differential makes their average speed equal that of the countershaft: CS=(W1+W2)/2. The issue you describe is that both wheels need to provide some resistance. If W1 has no load but W2 does, W1 will spin twice as fast as CS, and W2 will not spin at all.
The Power Split Device works on the same principle, but it has two inputs and one output. It also doesn't use straight averages: 18*ICE+5*MG1=13*MG2. Note that the motor-generators can spin backwards, so those terms can be negative. Then MG2 is connected to the countershaft, which is connected to the differential and then the wheels.
Using this information, we can explain some of the Car Care Nut's simplifications. Both MG1 and MG2, not just MG2, are used in EV mode, with 5*MG1=13*MG2. So ICE=0. This is equivalent to your experiment where one wheel was held stationary, and the hub was allowed to spin. To start the ICE, MG1 doesn't *increase* its speed, it *decreases* it. Or spins backwards, if the car is stationary.That way ICE has to start spinning to make the input speed (the combination of ICE and MG1) equal to the output speed. Just like how slowing your hub with the handbrake made the other wheel spin.
Hybrid drive is more complicated. At slow car speeds, MG1 controls the speed of the ICE by acting as a generator, resisting its spin and so slowing the "input." It sends power to the battery and/or MG2, which can add torque when acceleration is needed. At high car speeds, this reverses. MG2 actually resists the spin of the ICE, and sends power to MG1. The clever bit here is that MG1 can now increase the input speed of the three-way transmission, so the ICE doesn't have to.
Jeff and WillyAG, thank you so much! I still don't fully understand it all though. I've been watching WeberAuto's videos. How does MG1 and ICE, which are mechanically decoupled to MG1 (in the sense of you can spin them, but have MG2 held stationary), still contribute to torque production when under full acceleration?
I am trying to also understand how the under/direct/overdrive, under cruising mode, is achieved by using MG1 (forwards, stationary, and backward).
Also, when in EV mode, doesn't MG1 spin in the opposite direction to MG2 (assuming MG2 is the only motor that drives in motor mode), but when the ICE needs to kick in, it's MG1 that starts it. My understanding is that the flywheel connected to the ICE rotates in the same direction as MG2, but with MG1. This all means to me that MG1 all of the sudden rotates in the opposite direction. That can't be too good? Not sure if this makes sense what I am trying to say. I may lack the proper understanding of it all though.
(I always thought there was a CVT in the Toyota hybrids, but this eCVT is so different and quite a cool piece of engineering!)
@mark The device is technically called "Power Split Device," but you can think of it as a "Torque Split Device" as well. Because POWER=TORQUE*RPM, so splitting power is the same as splitting torque. The engineers have to use both to solve the control system, but the qualitative description doesn't need that.
"Opposite direction" is a little hard to define, since MGs can be motors, or generators, in either direction. I don't know what sign convention Toyota uses, but I wrote my equation so that positive torque by any of the three devices will push the car forward.
What may be confusing you, tho, is that nothing is ever "decoupled," but MG1 and ICE are coupled to ea h other first, and their net is coupled to the wheels. Most often when the ICE is running, one of the MGs will be a motor pushing the wheels forward, and the other will be a generator pushing back against it, the wheels, and the ICE. At slow speeds, MG1 is the generator. At higher speeds, MG2 is. This allows the ICE to stay within a narrow range of RPMs where it is most efficient, and approximates the difference between under- and over-drive.
In EV mode, both MG1 and MG2 push the wheels forward, with MG1=2.6*MG2. This way ICE=0, and both are in the positive direction in my system. MG1 slows down to start the ICE, by making it have to spin to cover the rpms it takes out. Depending on speed, that could mean changing direction, but there is no harm done.
This is one of the best videos on hybrid systems.
You have my gratitude amd appreciation. I felt like one of my elder brothers explaining. Comfortable pace to comprehend.
Prof John Kelly does a excellent job of disassembly of a Toyota E-CVT at the Weber Auto channel.
Dude I'm a old shade tree mechanic, and you help me understand so much. I wish I can add a Toyota hybrid to my old 350 Chevy truck.
Enjoying every bit of this explanation of Hybrid technology. What a marvel of engineering!
My 2023 Rav4 Hybrid XLE Premium arrives in two months. I am watching these videos to learn about my new vehicle. Thanks for sharing such complicated technology so clearly.
Yes, I learn something new from this video.Your explanation are easy to follow. Thanks a lot.
Amazing series. Everything I wanted to understand but no one at our local Toyota dealership had any clue about. Fantastic.
I feel the people that made the planetary gear system and this hybrid system and so many other parts of this hybrid possible. They are all genius's in their accomplishments!
In my opinon Toyota engineering over all is the best in this world , but like Honda fell in the past it appears that some of the newer Toyota models are not as good as the older models. I have a 2002 Tacoma with a 2.7 liter POWER HOUSE and automatic slick smooth transmission that has over 206,000 miles on it an runs and functions like new, no joke, also I own a 2013 Prius which is pretty much the same as the 2002 Tacoma Quality,Quality, Engineering, Engineering...
You might have mentioned that the "planetary" is a gearset, a kind of differential, and that the e-CVT is essentially a 1-speed transmission that requires help from MG2 to accelerate normally. Also, the Prius was introduced in Japan and elsewhere in 1997.
Wow I have a Prius and a rav4, both hybrids and I love them and I love this series even more. It’s so much simpler than I thought!!! It’s basic design and now I know what they call it regenerative braking! This is so damn cool! Prius has been hands down my most reliable Toyota to date and I have had two tercels, an older corona wagon, Camry, Prius and rav4. I love love love my Toyotas
One thing I have never done, and would never do is laugh at Toyota we own three of them one is a Highlander hybrid, and we just love it, Great video thank you
Great job, Couple of comments to amplify what you said, without getting too technical:
At 5:15, when you run the engine fast, the MG1 goes much faster, and so MG1 uses most of the engine power to send to MG2. So, engine spinning faster and wheels still spinning slow; That acts like a lower "gear" to make the CVT action work, even though no shiftable gears are involved.
At 7:00, battery can only take so much from MG2 on electro-braking. If more braking needed, the disc brakes kick in to help out.
The more I know about my toyota corolla hybrid the more I love it. Thanks for sharing your knowledge
A simple explanation of a complicated thing. Great video, thanks!
Watching ur hybrid videos has made me appreciate my auris hybrid way more. Thank you!
Thank you for this awesome video about the hybrid transmission. Now it makes totally sense about the electric motors when applying reverse. Also why is highly recommend NOT to tow anything. I just use my tow hitch to carry my bicycle
I used to laugh at prius….now that i understand the workings, im in awe! Such a cool design
Toyota hybrids are reliable because of what is NOT in newer Toyota hybrids when compared to other hybrids.
No Gears, No CVT Belts
No Starter
No Alternator
No Timing Belt
No Accessory Belt
No Conventional AC
No Turbochargers
No Power Steering Pump
How can the engine work without timing belt?
@@giannottister mg1 turns it on as if it were a starter.
@@giannottister It uses a timing chain, not belt. Just more reliable with zero service requirements.
@@mobgma Ah great, yes much more reliable, thanks.
I just purchased a new Rav4 hybrid and absolutely love it BUT Honda hybrids also have No to all of the above. Mind you Honda turbos are a major deal breaker for me.
Thank you, great work!
Clear, simple and to the point. And not to much input to get an understanding how things work.
I ALWAYS learn something new & useful watching your product videos ! Keep them rolling Mr CCN . 👌
Does mg2 generate back to the battery proportional to vehicle speed or deceleration force??
I've only just found this video and it has answered a lot of questions. I bought a Toyota Auris mainly because I saw how many taxi and hire car drivers were using them. Also because of the number on the market with over 100,000 miles on the clock but still commanding good prices. It all seemed to say "reliability" to me but I often wondered how the CVT promoted such reliability. Now I know - No Belts. I think my Auris is great by the way, easy to drive quiet, dependable and, as I have an estate version, I can get all my tools in the back!
I’ve also got the same model car that I purchased in September 2022 and I am really pleased with the car and the technology . The drive is so smooth and quiet and the fuel consumption is excellent.
Great video, very good explanation, this guy knows what he taking about. Keep up the good work👍 mine Lexus is300h F sport 2014 love the car!😁
man i just love your sense of humor. besides all the important stuff that you've been talking about since the first video, i subscribed to your channel because of your humor and that you always ask God to keep us safe (",)
Thank you for this series. The engineering of this technology is amazing.
I love your videos and i watch every single video. I am Continuing learning so many thing....
thanks for the great vid!! you're right its a very efficient system. my camry hybrid gives great mileage. i love the dynamic braking as well, it slows the vehicle down automatically.
I keep watching . And I keep thanking you.
So glad I’ve found this channel
one of my favorite YT Channels! Thank you!!
Hello: Great explanation. Thank you. I am looking forward to see more of your videos. Take Care and wish you well.
So the engine is NOT running the wheels...!?
That's BRILLIANT!!!
Your knowledge and advice are invaluable, I'm thinking of buying an ls600h 2010 model Your in depth advice is really useful, thankyou
Excellent delivery! Great job explaining.
Another great video, simple and clear !
But you forgot another great feature of the e-cvt : the variable ratio allows to cruise at relatively high speed with a very low engine speed : another bonus for the fuel economy !
Thank you Maxime! Hybrids are very interesting cars in the way they function
I've seen many videos about Toyota's hybrid system. Some are really fancy, with a lot of great graphics, but this is the best one and, by far, the clearest. I finally understand how this technological wonder works. Thank you so much!
May God bless you too for your brilliant inputs.
Once again great information as always God bless you and your family🤲
I never boring to learn from you, Thank you very much.
Good morning, this was the explanation I was looking for.
Thanks a lot for all your educational videos. God bless you.
Again a superb explanation. Nice! 👍
Very valuable information Thanks
simple but powerful..
Great video again, thank you. I have seen a video where a mechanic from Poland takes it apart and explain in detail how simple build it is.
The intriguing part is how it is actually changing a gear ratio, as I understood it actually uses the one of the MG to apply right amount of power or load to make planetary gear make the rest of the work. Simple yet sophisticated ;-)
I spoke to drive who did more then 800kkm with on the same gear in Prius.
Dear Sir. This is the best video that I've ever seen. You were covered a lot in details about the Hybrid car. I had an ES300h Lexus and I'm try to learn about the car how does it work. Thanks a lot for your contribution the knowledge. I'm very enjoy your channel. Take care.
Your videos are fascinating. Thank you.
Good Morning Great info picking up a 2023 highlander hybrid. Thanks for your information..
Weber Auto does a great deep dive into the Toyota transaxle...
Thanks I own a hybrid shop and still learn new things from you. Now I know why the computer makes the car stall if engine is running poorly. I have a mechanic friend who replaced a prius engine thinking it was bad because of all the noise. I tried to tell him that the engine is it’s just misfiring. And I have always thought it was the valve not realiizing it is the transmission making all that noise because it does sound like it is coming from the transmission. Thanks so much
I've worked on traditional cars since the late-70's and the hybrid transmission and relationship with the ICE was, probably, the most difficult to picture in my head. Excellent explaination and answered a lot of my questions. The hybrid cannot run just on the gas engine (MG1) because the MG2 is electrical so if the traction battery isn't working, the car isn't going anywhere! So the "boost" we feel when punching the gas pedal does rev up the engine but the power to the wheels is from the boost in electrical inputs to the MG2, not the RPM's from the engine, right? The only "gear" in the transmission is the parking gear so we can't just put it in neutral and tow the car around, like an RV can tow some cars...Prius would have to have front drive wheels up on a trailer (And all 4 wheels up for AWD versions) All this stuff is fascinating and, you're right, Toyota has some genius engineers to come up with this! (In 2019, we drove our 2017 Prius from Colorado to Maine and back and only spent $200 total for gas the entire three weeks!)
I drove Camry one time and I asked: HOW!? I must be super complicated. Then I search yt for its' components and now I want only this type of drive. Toyota's eCVT is miracle!
You said them all!!!
Superb presentation !!!
Awesome!
I learn so much with your easy to understand explanation! I think you should use a Prime in future hybrid (Prius or RAV4 Prime) as an example as it's an extension of a hybrid.
Looking forward to your future expert videos.
In the end we gaint nothing ... lol ... .. and again a great video.. thanks 4 sharing your knowlidge sir Amd..
very educative. thank you regards,
Thanks for breaking this down
Great job. Thanks
Thank for explanation of the clattering 👍
Brilliant series
Wow this is so impressive to me!
Clear and excellent explanation!
Very informative video. Thank you
What I love about my 2022 Camry hybrids transmission is how instantaneous it changes from forward to reverse. It’s very responsive
Thank you!
Amazing.
Awesome discussion
Great vid, thanks!
Nice explanation.
I love your videos.
Weber Auto clip does go into a LOT of detail of how the eCVT works for those with a nack
Weber by far is the single source for the Hybrid cars system, I think you do a great overall job regarding Toyota Hybrids and other Toyota products.😎
This helps thank you
short and to the point
Thanks I was never clear on mg1 and mg2. This video did a great job in explaining the difference and the purpose of each. Also I have experienced my car making that loud noise at start as if the engine was going to blow a couple of years back, it scared the heck out of me. Now I know it was the transmission and not the engine.
Mine did the same thing few weeks ago. And it happend in the morning after nigth short turn on and off the system for moving car a bit for parking purpose. Now I dont turn off my prius until it turns off engine itself
@@quoprimum5215 But according to what he says here, there is something wrong with the transmission right ? It's one thing to explain what the car shuddered and made the noise, but it would have been nice if he explained what caused the transmission to do this ( is it going out? is it needing maintenance ? does this throw an engine code ? etc )
Many dealers plus Toyota it self not explained any of that so consumers consider hybrid vehicle as first option!!!!
Educated people is the best way to understand and decide what fit for them requirements
Wow...
Really a good top-level discussion. There are many CZcams videos that discuss the hardware & functionality in more detail.
RE fluid change: Toyota claims this never needs changing, but there are drain & fill plugs. I changed mine at 30K miles, and the fluid was very dark compared to the new fluid. I changed it again at 90K miles & the fluid looked almost new. So, there may be some benefit to changing the original fluid at 30K miles.
Toyota didn’t invent the Hybrid Synergy Drive. Ford invented it many years ago, but they couldn’t see a market for such a vehicle. They sold the rights to Toyota.
The engine is always mechanically connected to the front wheels. The eCVT operates like a torque converter when the vehicle is stopped and the engine is running. The direct connection between the engine & front wheels limits the vehicle top speed to the max engine RPM, about 115 MPH.
There actually is a clutch between the engine and the transmission. It doesn’t function as a conventional clutch in normal operation - there’s no mechanism to disengage it. It functions as a mechanical “fuse” to disconnect the engine from the front wheels in case the engine seizes up while driving.
The engine is not mechanically connected to the wheels. MG2 is mechanically connected to the wheels.
@@duhboi6516 The ICE drives the planet gears, which engage with the ring gear that is ultimately connected to the wheels. So yes, there is a direct mechanical connection between the ICE and the wheels. MG2 also drives the ring gear.
Very nice and informative video
Thanks so much
Shout out to Toyota engineers..! 🚙
Once you realise MG1 spins forwards and backwards to vary the ratio in the planetary gear system, the whole gearbox just makes sense working with MG2 and the ICE.
Very important and often missed point!
Wow thanks
Ty!
I just watched all four episodes of "How Toyota Hybrid System Work" series and I really thank you for the information and your valuable experience that you shared with us. They will certainly help to use my new Yaris more safely and efficiently.
I would also like to ask a question that arose for me. Since the regenerative braking done by the electric motor is applied to the two front wheels only, doesn't this lead to significantly uneven tire wear between the front and rear axles?
this is true for most FWD cars. Weight moves forward while braking, so front tires can handle more grip before slipping. Therefore, the front wheels tend to get increased braking bias.
Awesome Video......:)
Great Video. Can you please do a video explaining how E-Four system works? I am referring to vehicles like the Highlander, Rav4, and now Venza/Harrier hybrids with the third electric motor on the rear axle..
Thank You Sir!
@ 11:02 I was another of your viewers who asked about the transmission fluid last month. Luckily I had used the WS transmission fluid but was worried that if I had put the correct one and also thought that my mechanic didn’t do the right procedures to bring the fluid to the correct level. 😂
Thank you for watching my hybrid series Michael!
Going through your entire Hybrid playlist, I went from looking at a Sienna to a Highlander but ended up ordering through Carvana a 95000 mile 2013 Prius V, I think it should make a better daily driver for work commute plus the whole family when needed.
First think I'll check when the car arrives, the hybrid battery fan filter.
Congratulations on your Prius v purchase. The fan filter is underneath the passenger rear seat. Slide the seat all the way forward to see it. If no filter is installed install one and keep it clean and clear and you should have no issues
You will not be sorry as the Prius is probably the best engineered car out there my 2013 Prius base model speaks for itself over 160,000 miles with few problems and almost Zero service other than required!
It's a brilliant design. Helps explain how I get close to 700 miles per tank on 2022 Sienna.
Is not a eCVT it is a PSD (Power split differential) And MG1 is not directly connected to the Combustion motor, but it is connected to it through the PSD. And the speed of MG1 will control how much power the ICE can give, that's why at high speed you can have the ICE at low rpm. This is a fantastic trasmission because you can have very high gear ratio for economy. I also hope Toyota makes a High performance Hybrids, because I'm sure this trasmissione can also be very sporty!
Planetary Gear System: basically allows the front & rear wheels to allow travel at different speeds in a turn. 6 gears come together top to bottom and all four sides. This allows the wheels to turn at different rates of speed.
That is basically what a Planetary Gear System works.
The MG's have rotating permanent magnets which allow them to be both motor and generator and brushless too. They are three phase motors. Very efficient and powerful.
👏👏👏👏👏
Your cool.
And the RAV4 (and a few 4WD Prius) has I think kind of another MG2 in the rear. The people who were laughing at Prius were doing so out of spite for what they don’t know.
Yes sir! The motor in the back is called MGR