Ford Patents 11-Speed Automatic Transmission
#16
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CVTs are superior to small cars but they do have a NVH problem in small NA 4cly engines where they have to keep engine in 5000-5500 RPM range to accelerate, thats pretty annoying but overall it is still better than small AT from efficiency/cost perspective. CVT's in small turbos should be quite good, since they wont rev past 3000 rpm... I believe that in new small 1.2t Toyota turbo engine, CVT transmission is rated better than long geared 6 speed manual.
#17
Lexus Fanatic
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i meant more like higher end luxury vehicles than small cars.
CVTs are superior to small cars but they do have a NVH problem in small NA 4cly engines where they have to keep engine in 5000-5500 RPM range to accelerate, thats pretty annoying but overall it is still better than small AT from efficiency/cost perspective. CVT's in small turbos should be quite good, since they wont rev past 3000 rpm... I believe that in new small 1.2t Toyota turbo engine, CVT transmission is rated better than long geared 6 speed manual.
CVTs are superior to small cars but they do have a NVH problem in small NA 4cly engines where they have to keep engine in 5000-5500 RPM range to accelerate, thats pretty annoying but overall it is still better than small AT from efficiency/cost perspective. CVT's in small turbos should be quite good, since they wont rev past 3000 rpm... I believe that in new small 1.2t Toyota turbo engine, CVT transmission is rated better than long geared 6 speed manual.
A CVT just has to be set up in a way that it can replace a modern day AT.
Like I said earlier, my CVT has 7 simulated shifts, those who have driven my vehicle would never know that it was a CTV. Other CVTs obviously do not have this set up as they are more like the traditional style that everyone hates (I hated my CT200h drivetrain)
CVTs are usually set up for fuel economy first and driving performance second. But a CVT can be set up so it simulates an AT.
I have also heard from a few friends who work in engineering at Ford that ultimately a CVT will out perform an AT in the long run.
Just some food for thought, the 290hp Nissan Maxima has a CVT and it can do 0-60 in 5.8 seconds, it has 6 simulated shifts and has over 700 shift points programmed for real world driving.
#19
Lexus Fanatic
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Originally Posted by spwolf
CVTs are superior to small cars but they do have a NVH problem in small NA 4cly engines where they have to keep engine in 5000-5500 RPM range to accelerate, t
#20
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i meant more like higher end luxury vehicles than small cars.
CVTs are superior to small cars but they do have a NVH problem in small NA 4cly engines where they have to keep engine in 5000-5500 RPM range to accelerate, thats pretty annoying but overall it is still better than small AT from efficiency/cost perspective. CVT's in small turbos should be quite good, since they wont rev past 3000 rpm... I believe that in new small 1.2t Toyota turbo engine, CVT transmission is rated better than long geared 6 speed manual.
CVTs are superior to small cars but they do have a NVH problem in small NA 4cly engines where they have to keep engine in 5000-5500 RPM range to accelerate, thats pretty annoying but overall it is still better than small AT from efficiency/cost perspective. CVT's in small turbos should be quite good, since they wont rev past 3000 rpm... I believe that in new small 1.2t Toyota turbo engine, CVT transmission is rated better than long geared 6 speed manual.
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#21
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I have CVT in both the IS 300h and CT 200h and it works perfectly for daily driving. The only problem is when it comes to sporty driving. The delay in throttle response is from another world, I have actually driven my CT on a track
and its the only car I know you almost need to floor before the turn in to get full power when you reach the straight again.
Yes , I know that the CT wasn´t made for that kind of driving.
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#22
Lexus Champion
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I have CVT in both the IS 300h and CT 200h and it works perfectly for daily driving. The only problem is when it comes to sporty driving. The delay in throttle response is from another world, I have actually driven my CT on a track and its the only car I know you almost need to floor before the turn in to get full power when you reach the straight again. Yes , I know that the CT wasn´t made for that kind of driving.
The eCVT (Electronic CVT) in Toyota and Lexus hybrids is not a real CVT. In fact, it is not even a real transmission at all because the gas engine never directly drives the wheels; the electric drive motor is always directly driving the wheels. So a Toyota / Lexus hybrid vehicle is actually an electric car with a petrol engine backup.
The eCVT is a Power Split Device, a computer-controlled gearset that allows the engine to do 2 functions:
- The engine can add power to assist the electric motor (when accelerating hard or driving at higher speeds, since neither the electric motor nor the hybrid battery are that powerful);
- It can recharge the hybrid battery; or
- It can both assist the electric drive motor AND recharge the hybrid battery at the same time.
Current state-of-the-art belt-and-pulley CVTs would not work on the Lexus LS, since the 5-litre V8 engine (on the LS 600h) would have too much torque for the gearless belt-and-pulley CVT. So much torque would make the belts slip on the pulleys.
#23
Lexus Test Driver
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Slightly incorrect, the gas engine *can* drive the wheels directly at high speed. This usually happens at freeway speeds with the traction motor adding more power if necessary.
I think Toyota calls their hybrid transmissions eCVT because there are no set gear ratios, with the traction motor and ICE both providing continuous power up to a set RPM limit. The planetary gear set Power Split Device used in Toyota hybrids is totally different than a typical Honda or Nissan CVT with belts and cones.
I think Toyota calls their hybrid transmissions eCVT because there are no set gear ratios, with the traction motor and ICE both providing continuous power up to a set RPM limit. The planetary gear set Power Split Device used in Toyota hybrids is totally different than a typical Honda or Nissan CVT with belts and cones.
#24
Lexus Champion
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Slightly incorrect, the gas engine *can* drive the wheels directly at high speed. This usually happens at freeway speeds with the traction motor adding more power if necessary.
I think Toyota calls their hybrid transmissions eCVT because there are no set gear ratios, with the traction motor and ICE both providing continuous power up to a set RPM limit. The planetary gear set Power Split Device used in Toyota hybrids is totally different than a typical Honda or Nissan CVT with belts and cones.
I think Toyota calls their hybrid transmissions eCVT because there are no set gear ratios, with the traction motor and ICE both providing continuous power up to a set RPM limit. The planetary gear set Power Split Device used in Toyota hybrids is totally different than a typical Honda or Nissan CVT with belts and cones.
The main difference between a belt-and-pulleys CVT and the eCVT is this:
- In the CVT, the car's speed is regulated by the variable gear ratios of the belt and pulleys. As the car speeds up or slows down, the gear ratio changes, allowing the engine rpm to remain constant.
- In the eCVT, the car's speed is regulated by the electric drive motor (Motor-Generator 2 or MG2). As the car speeds up or slows down, the speed of MG2 changes; the engine rpm remains constant. If the engine were directly connected to the drive wheels, engine rpm would have to change as the car's speed changes; it would no longer be an engine rpm-constant "CVT". Excess power produced by the engine that is not needed by MG2 to drive the car is absorbed by Motor-Generator 1 (MG1) acting as a generator to recharge the hybrid battery.
#26
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But yes, in smaller 4cly vehicles, when you need full acceleration, they will certainly go to high rpms and produce pretty annoying noise, which is basically not fault of CVT, but combination of less powerful engine, less luxurious soundproofing and need for maximum acceleration. When paired with smaller cheap vehicle, it gets annoying.
I recently drove Yaris 1.33 CVT and while I would buy it for my wife, I could never own it myself... less powerful engines and cvt means high rpm's, and cheap car with poor sound insulation means a lot of annoying noise... new MMC Yaris is supposedly much nicer but I dont think it can ever be awesome with that engine getting up to hwy speeds.
Hybrids PSD (aka eCVT) gets extra benefit of electric motor acting like 40-50hp instant turbo so you dont get anywhere as much annoying noise since you accelerate much quicker with 40hp boost.
#28
Lexus Fanatic
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Originally Posted by LexsCTJil
The LS600h weighs 5600 lbs, that is Toyota Tundra territory and it uses a CVT and has AWD.
http://www.lexus.com/models/LS-hybrid/specifications
#29
Lexus Champion
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I am not sure that the Volt can either, but Honda claims that the current Honda Accord Hybrid can.
The HAH is the only 2-motor hybrid that I know of in which its petrol engine can directly drive its wheels at high speeds. Of course, all the 1-motor hybrids (like Audi, Hyundai, Honda IMA, etc.) that merely add an electric motor to the front of the transmission, have the petrol engine directly drive the wheels at high speeds.
The HAH is the only 2-motor hybrid that I know of in which its petrol engine can directly drive its wheels at high speeds. Of course, all the 1-motor hybrids (like Audi, Hyundai, Honda IMA, etc.) that merely add an electric motor to the front of the transmission, have the petrol engine directly drive the wheels at high speeds.
#30
Lexus Fanatic
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I am not sure that the Volt can either, but Honda claims that the current Honda Accord Hybrid can.
The HAH is the only 2-motor hybrid that I know of in which its petrol engine can directly drive its wheels at high speeds. Of course, all the 1-motor hybrids (like Audi, Hyundai, Honda IMA, etc.) that merely add an electric motor to the front of the transmission, have the petrol engine directly drive the wheels at high speeds.
The HAH is the only 2-motor hybrid that I know of in which its petrol engine can directly drive its wheels at high speeds. Of course, all the 1-motor hybrids (like Audi, Hyundai, Honda IMA, etc.) that merely add an electric motor to the front of the transmission, have the petrol engine directly drive the wheels at high speeds.
Parallel hybrids, on the other hand, were like those pioneered by the Toyota Prius and similar Ford units first built under Toyota license....the gas and electric motors can each drive the wheels independent of the other, as conditions and battery charge warrant. Since then, of course, several other types of hybrids have also been introduced, some with individual electric motors at each rear wheel and behind or parallel to the gas engine.