Post by firemac on Oct 17, 2020 11:12:42 GMT
This is an interesting read:
Toyota’s Direct Shift-CVT and How It Works
17 October 2020, 08:39 UTC · By Vlad Radu
Toyota’s Direct Shift-CVT and How It Works
Toyota’s rise to automotive highs is well documented. They took the world of endurance racing by storm and pioneered many innovative technologies. Among them, the Direct Shift-CVT transmission.
The CVT, or continuously variable transmission, is not a new idea, many car manufacturers use this technology instead of a traditional transmission. This evolution comes from the desire to create more fuel-efficient cars.
A normal CVT transmission uses pulleys and a belt instead of fixed gears to connect the transmission to the wheels, but the transmission has fewer moving parts, and it allows the engine to run using the most fuel-efficient RPM’s.
The downside is that it can also give the drivers a disconnected feel for the car since there is no movement through gears.
Although they are more efficient, they are often less responsive when starting the car from a complete stop, and overtaking when traveling at low speeds is not always a clever idea.
A high percent of drivers also misses the feel of the car shifting through the gears. A regular CVT’s ratio tries to match the engine speeds instead of the other way around.
If you press the gas pedal all the way down, the engine seems to rev uncoordinated with the actual acceleration of the car. This happens because a CVT works to keep the engine running at peak torque to make it more efficient.
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Toyota paid attention to driver feedback about conventional CVTs and made some exciting changes to their Direct-Shift solution.
The Direct\-Shift CVT
The upgraded system uses a launch gear to give drivers the feel of a traditional transmission, and it will also do its job of improving efficiency in the lower gear ratios.
This new launch gear is just like the first gear of a regular transmission; as the car starts to pick up speed, it switches off and starts working as a normal continuously variable transmission.
By using these fixed ratio gears, the new transmission will improve the efficiency of the belt and help increase the shift speed ratio, which results in better performance.
The moving parts inside Toyota’s new transmission have much less wear due to the presence of the launch gear that handles the highest input loads as the car gets up to speed.
As a result, the Direct Shift-CVT can use a narrower belt angle which Toyota reduced from 11 degrees to 9 degrees. This apparently minor modification increases the shift speed by no less than 20 percent.
Also because of these modifications, the new system uses a more compact pulley. Since the launch gear reduces most of the belt load, a smaller pulley helps to improve shift responsiveness.
In turn, the reduced inertia helps to make shifting more responsive. Because of these design changes, acceleration is a lot more powerful and more rhythmic than any other conventional CVT.
This exciting and innovative design helps make Toyota cars more efficient and a lot more fun to drive. The transmission debuted on the 2019 Toyota Corolla hatchback that came with the new 2.0-liter Dynamic four-cylinder engine. Another beneficiary of this new system is the Toyota GR Yaris.
Toyota’s Direct Shift-CVT and How It Works
17 October 2020, 08:39 UTC · By Vlad Radu
Toyota’s Direct Shift-CVT and How It Works
Toyota’s rise to automotive highs is well documented. They took the world of endurance racing by storm and pioneered many innovative technologies. Among them, the Direct Shift-CVT transmission.
The CVT, or continuously variable transmission, is not a new idea, many car manufacturers use this technology instead of a traditional transmission. This evolution comes from the desire to create more fuel-efficient cars.
A normal CVT transmission uses pulleys and a belt instead of fixed gears to connect the transmission to the wheels, but the transmission has fewer moving parts, and it allows the engine to run using the most fuel-efficient RPM’s.
The downside is that it can also give the drivers a disconnected feel for the car since there is no movement through gears.
Although they are more efficient, they are often less responsive when starting the car from a complete stop, and overtaking when traveling at low speeds is not always a clever idea.
A high percent of drivers also misses the feel of the car shifting through the gears. A regular CVT’s ratio tries to match the engine speeds instead of the other way around.
If you press the gas pedal all the way down, the engine seems to rev uncoordinated with the actual acceleration of the car. This happens because a CVT works to keep the engine running at peak torque to make it more efficient.
Recommended videosPowered by AnyClip
2020 Toyota Corolla Overview
1.4K
Ad: (4)
Toyota paid attention to driver feedback about conventional CVTs and made some exciting changes to their Direct-Shift solution.
The Direct\-Shift CVT
The upgraded system uses a launch gear to give drivers the feel of a traditional transmission, and it will also do its job of improving efficiency in the lower gear ratios.
This new launch gear is just like the first gear of a regular transmission; as the car starts to pick up speed, it switches off and starts working as a normal continuously variable transmission.
By using these fixed ratio gears, the new transmission will improve the efficiency of the belt and help increase the shift speed ratio, which results in better performance.
The moving parts inside Toyota’s new transmission have much less wear due to the presence of the launch gear that handles the highest input loads as the car gets up to speed.
As a result, the Direct Shift-CVT can use a narrower belt angle which Toyota reduced from 11 degrees to 9 degrees. This apparently minor modification increases the shift speed by no less than 20 percent.
Also because of these modifications, the new system uses a more compact pulley. Since the launch gear reduces most of the belt load, a smaller pulley helps to improve shift responsiveness.
In turn, the reduced inertia helps to make shifting more responsive. Because of these design changes, acceleration is a lot more powerful and more rhythmic than any other conventional CVT.
This exciting and innovative design helps make Toyota cars more efficient and a lot more fun to drive. The transmission debuted on the 2019 Toyota Corolla hatchback that came with the new 2.0-liter Dynamic four-cylinder engine. Another beneficiary of this new system is the Toyota GR Yaris.
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