The Infinitely Variable Transmission (IVT) has the drivability benefits and proven fuel economy benefits superior to anything offered by conventional transmission systems.

However, current IVTs are bulky and complex because of operational constraints at high temperatures. As high temperatures traction fluid viscosity in IVTs is low the results is reduced transmission efficiency. The high temperatures also hasten component failures. Current IVTs (like the well-known Torotrak IVT) are built with up to six variator rollers and at least two pairs of variator disks in order to improve traction efficiency and distribute traction stress during operation, all because of the temperature problem.

IIL has a novel IVT design that solves the high temperature problem, thus allowing a very simple integration that uses just a pair of variator rollers and a pair of variator disks in coaxial assembly with a planetary gear set.

The complex hydraulics and electronics for the torque-based control mechanism is now also unnecessary in the IVT.

The IVT is a split-power transmission system wherein the input shaft delivers power along two paths and to a planetary gear set that combines the power from the two paths. The ring gear of the planetary gear set provides output to the final drive. The geared neutral condition is achieved at a particular speed through the variator unit when the carrier member and the sun gear speeds add up to result in the zero ring gear speed. The IVT shifts from reverse through geared neutral and to forward, and vice versa, without interruption.

The IVT uses a torque-based control system that facilitates automatic ratio shifting wherein the variator disks swivel the rollers towards the best drive ratio. The transmission is in neutral when the variator disks do not swivel the rollers. This makes the operation of the IVT very simple. The driver of a vehicle need only set the IVT to either forward or reverse and step on the accelerator and the IVT will automatically seek out the best drive ratio.

A slight nudge on the variator control shafts provides the gear shifting operation in the IVT, with the drive ratio dependent on the torque input and therefore adjusted automatically. The gear shifting method of the IVT is simpler than any gear shifting method employed in any conventional variable ratio transmission system. The power requirements for the control system are thus greatly minimized in the IVT.

The automatic transmissions (ATs) and continuously variable transmissions (CVTs) are popular transmission systems owing to the ease in driving that they provide compared to the manual transmissions (MTs). However, these transmission systems are notoriously inefficient and complex assemblies.

In the ATs, the hydraulic slippage within the torque converter causes fuel-consuming high engine RPMs. In CVTs, the slippage between the drive belt and the pulleys also causes the fuel-consuming high-engine RPMs. Both of these transmission systems have relatively large power requirements for the hydraulic control systems used for the clutches in the ATs and the pulleys in the CVTs.

The compact configuration of the traction variator, the elimination of the high-power requirements and the now regulated temperature in the IIL IVT provide more benefits than can be realized from ATs, CVTs, and other IVTs.

Commercial Appeal of IVT

Drivers want to be rid of the exhausting work of shifting gears especially in stop-and-start traffic conditions. They want to be able to simply shift to the desired drive mode, step on the accelerator, and then let the transmission system adjust to the best drive ratio without the need for more manual gear shifting. And because of environmental concerns and rising fuel prices, they also demand fuel efficient transmission systems.

But the current MTs, ATs, and CVTs just can't provide driving ease and fuel efficiency in the same package. Hence, there is a demand for better technologies; and thus production investments are expected for light-vehicle automatic transmission systems.

Production systems for light vehicle transmission systems are cheaper and faster to establish. They incur less overhead costs in operation and less materials costs for each unit produced. Considering these factors, it is therefore easy to see that extensive growth in the light-vehicle transmission systems market is imminent.