Video shows how eCVT works in a Toyota/Ford vehicle

[fbov]

I still don’t get how the transmission changes ratios

...

After owning NISSAN CVT tech for many years...

Anyone thinking of this as your grandfather's 2-shaft CVT will not understand a 3-shaft CVT. The basic idea is elegant but before it's time (1972), so it's not particularly new... just a lot newer than the "classical" approach.
US3732751.pdf

It's important to understand that electric motors can:
- turn in either direction to generate electricity or drive torque
- spin as fast as 15,000-18,000 RPM, while generating current-limited torque from 0 RPM.

The transmission changes ratios by changing shaft speed. It has three shafts, but only two are constrained. It's the classic "three equations with two unknowns." Having one shaft unconstrained in speed or torque enables a wide range of speed ratios.

In the planetary gear set, the Ring gear is tied to road speed, along with the traction motor. As a result, the traction motor always starts at 0 RPM when stopped, and its redline defines top speed. This motor's gear ratio is fixed in 1st gear (~4:1 ratio to the ring gear, 10-11:1 to the axel).

The second shaft-of-interest is the ICE, which can only turn in one direction, and whose speed and load we want to control for maximum efficiency. It's the Sun gear in our planetary gear set. ICE will provide power in two different paths, series mode by generating electricity (Sun drives Planets), and parallel hybrid mode in direct drive/overdrive (Sun drives Ring).

Series Mode
- when stopped, the ring gear is stationary, so Sun RPM = Planet RPM (the planet carrier drives the charging motor). This allows ICE to idle while stopped and generate electricity.
- to move from a stop (ring gear stationary), ICE RPM rises quickly to high power, which goes into the planet gears that spin the charging motor to generate electricity.
- AC power from the charging motor feeds the traction motor, which has ~25% more torque than ICE, and can deliver it from a stop if you give it the current.

When the HVB is providing the drive current in series mode (ICE stopped), we call it EV mode.

Parallel Mode
At cruising speed, the ring gear is moving fast enough to reach the ICE power band and enable direct drive. Charging motor speed is used to control ICE operating RPM. ICE power is apportioned one of two ways, depending on load:
- at low drive load (flat/downhill), drive torque is split between the road and generating electricity to charge the HVB (ICE-only mode)
- at high drive load (uphill), drive torque to the road is augmented by traction motor torque from the HVB (Hybrid mode)

Without a simulator, it's hard to see how some of this works. Thus these videos. The key is understanding that there are no sharp boundaries; the control system seamlessly blends the various modes. As ICE becomes unhappy with falling road speed, more of its power is diverted to generating current for the traction motor. At high speed, ICE slips into an overdrive mode when the HVB is full (no charging load).

It's all about speed ratios: all gear ratios are fixed but the third shaft's speed is relatively unconstrained.

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[mamboman777]

...

Anyone thinking of this as your grandfather's 2-shaft CVT will not understand a 3-shaft CVT. The basic idea is elegant but before it's time (1972), so it's not particularly new... just a lot newer than the "classical" approach.
US3732751.pdf

It's important to understand that electric motors can:
- turn in either direction to generate electricity or drive torque
- spin as fast as 15,000-18,000 RPM, while generating current-limited torque from 0 RPM.

The transmission changes ratios by changing shaft speed. It has three shafts, but only two are constrained. It's the classic "three equations with two unknowns." Having one shaft unconstrained in speed or torque enables a wide range of speed ratios.

In the planetary gear set, the Ring gear is tied to road speed, along with the traction motor. As a result, the traction motor always starts at 0 RPM when stopped, and its redline defines top speed. This motor's gear ratio is fixed in 1st gear (~4:1 ratio to the ring gear, 10-11:1 to the axel).

The second shaft-of-interest is the ICE, which can only turn in one direction, and whose speed and load we want to control for maximum efficiency. It's the Sun gear in our planetary gear set. ICE will provide power in two different paths, series mode by generating electricity (Sun drives Planets), and parallel hybrid mode in direct drive/overdrive (Sun drives Ring).

Series Mode
- when stopped, the ring gear is stationary, so Sun RPM = Planet RPM (the planet carrier drives the charging motor). This allows ICE to idle while stopped and generate electricity.
- to move from a stop (ring gear stationary), ICE RPM rises quickly to high power, which goes into the planet gears that spin the charging motor to generate electricity.
- AC power from the charging motor feeds the traction motor, which has ~25% more torque than ICE, and can deliver it from a stop if you give it the current.

When the HVB is providing the drive current in series mode (ICE stopped), we call it EV mode.

Parallel Mode
At cruising speed, the ring gear is moving fast enough to reach the ICE power band and enable direct drive. Charging motor speed is used to control ICE operating RPM. ICE power is apportioned one of two ways:
- drive torque split between road and generating electricity to charge the HVB (ICE-only mode)
- drive torque to the road is augmented by traction motor torque from the HVB (Hybrid mode)

Without a simulator, it's hard to see how some of this works. Thus these videos. The key is understanding that there are no sharp boundaries; the control system seamlessly blends the various modes. As ICE becomes unhappy with falling road speed, more of its power is diverted to generating current for the traction motor. At high speed, ICE slips into an overdrive mode when the HVB is full (no charging load).

It's all about speed ratios: all gear ratios are fixed but the third shaft's speed is relatively unconstrained.

 

[AREA52]

...

Anyone thinking of this as your grandfather's 2-shaft CVT will not understand a 3-shaft CVT. The basic idea is elegant but before it's time (1972), so it's not particularly new... just a lot newer than the "classical" approach.
US3732751.pdf

It's important to understand that electric motors can:
- turn in either direction to generate electricity or drive torque
- spin as fast as 15,000-18,000 RPM, while generating current-limited torque from 0 RPM.

The transmission changes ratios by changing shaft speed. It has three shafts, but only two are constrained. It's the classic "three equations with two unknowns." Having one shaft unconstrained in speed or torque enables a wide range of speed ratios.

In the planetary gear set, the Ring gear is tied to road speed, along with the traction motor. As a result, the traction motor always starts at 0 RPM when stopped, and its redline defines top speed. This motor's gear ratio is fixed in 1st gear (~4:1 ratio to the ring gear, 10-11:1 to the axel).

The second shaft-of-interest is the ICE, which can only turn in one direction, and whose speed and load we want to control for maximum efficiency. It's the Sun gear in our planetary gear set. ICE will provide power in two different paths, series mode by generating electricity (Sun drives Planets), and parallel hybrid mode in direct drive/overdrive (Sun drives Ring).

Series Mode
- when stopped, the ring gear is stationary, so Sun RPM = Planet RPM (the planet carrier drives the charging motor). This allows ICE to idle while stopped and generate electricity.
- to move from a stop (ring gear stationary), ICE RPM rises quickly to high power, which goes into the planet gears that spin the charging motor to generate electricity.
- AC power from the charging motor feeds the traction motor, which has ~25% more torque than ICE, and can deliver it from a stop if you give it the current.

When the HVB is providing the drive current in series mode (ICE stopped), we call it EV mode.

Parallel Mode
At cruising speed, the ring gear is moving fast enough to reach the ICE power band and enable direct drive. Charging motor speed is used to control ICE operating RPM. ICE power is apportioned one of two ways, depending on load:
- at low drive load (flat/downhill), drive torque is split between the road and generating electricity to charge the HVB (ICE-only mode)
- at high drive load (uphill), drive torque to the road is augmented by traction motor torque from the HVB (Hybrid mode)

Without a simulator, it's hard to see how some of this works. Thus these videos. The key is understanding that there are no sharp boundaries; the control system seamlessly blends the various modes. As ICE becomes unhappy with falling road speed, more of its power is diverted to generating current for the traction motor. At high speed, ICE slips into an overdrive mode when the HVB is full (no charging load).

It's all about speed ratios: all gear ratios are fixed but the third shaft's speed is relatively unconstrained.
[Very good! Is Ford incorporating Synchronous Reluctance (SR) motor technology or standard PM motor designs? Is gearing precision at minimum (< 18 arc seconds) backlash?

 

[fbov]

Very good! Is Ford incorporating Synchronous Reluctance (SR) motor technology or standard PM motor designs? Is gearing precision at minimum (< 18 arc seconds) backlash?

Ford is using AC synchronous motors, but the choice of motor design can vary. John Kelly's videos will show you who uses what. I haven't gone through any of the gear set-up videos.

 

[scotty]

True, because that starter/generator is inside the transmission housing.

Are those two motors within the tranny, part of the tranny that actually would fall under the tranny warranty?

 

[oljackfrost]

Are those two motors within the tranny, part of the tranny that actually would fall under the tranny warranty?

I would think the entirety would fall under the powertrain warranty.

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