Continuous Variable Transmission (CVT)

What is a CVT
How the CVT works
Merits of Honda's new torque converter-equipped CVT
Summary

What is a CVT (Continuously Variable Transmission)?

A CVT is a transmission that can change without steps, eliminating the need for gear changes.

Before we examine how the CVT works, let’s take a look at its merits.

If a bicycle were equipped with a continuously variable transmission, it would maintain just the right pedal weight for minimum exertion, whether starting off, cruising, or climbing a hill.

The reason:
In a CVT, the drive gear ratio can be continuously changed to maintain the right pedal weight for the driving conditions, eliminating the need to shift up and down between 1st gear, 2nd gear, 3rd gear, and so on.

When this principle is applied to an automobile:

The engine continually maintains a low-load rpm during acceleration.

Conclusion

The CVT allows the engine to continuously maintain the optimum speed for low-road operation, resulting in powerful performance combined with superior fuel economy.

How the CVT works

The Honda CVT combines a drive belt with variable-diameter pulleys to transmit power with a continuously variable ratio.

Merits of Honda's new torque converter-equipped CVT

As a step in our ongoing efforts to make the CVT even more comfortable, Honda has developed a CVT equipped with a torque converter, just like the ones used in automatic transmissions.

Let’s take a look at some of the merits of a torque converter-equipped CVT.

What is a torque converter?

Just as turning on a fan will cause a pinwheel to start spinning, a torque converter uses engine output to turn a pump, which in turn powers a turbine via a hydraulic coupling.

When the oil exits the turbine, it flows in the opposite direction to the pump's rotation. A stator is used to reverse the direction of oil flow, helping the pump to turn more easily.

This effectively amplifies the amount of torque transmitted.

Merit 1

Powerful acceleration for comfortable, sporty driving.

During initial startup and acceleration, the torque converter effectively increases engine torque. This allows the Honda CVT with torque converter to deliver smooth, powerful off-the-line acceleration.

Honda is focused on delivering efficient driving performance. That’s why we have designed the CVT to detect strong centrifugal force acting on the car and maintain high engine rpms even when the driver eases off on the accelerator on winding roads.

This allows the car to react to the driver’s modulation of the accelerator pedal with power and sensitivity, for sportier driving performance.

Merit 2

Torque amplification also improves fuel economy.

The torque converter amplifies torque for powerful off-the-line performance. This delivers ample acceleration with less load on the engine than previous models, further improving fuel economy.

Honda Insight Front

Summary
	What CVT is a user and environmentally friendly automatic type transmission. While the concept of a CVT transmission is as old as the motor car itself, it has taken Honda to re-engineer the idea to suit the demands of the 21st Century, including full grade logic electronic control with drive and sport modes. Where CVT is available in the Honda Civic, Honda Insight and Honda CRZ replacing the conventional 'automatic' transmission. CVT fully complements these low emission engines.
The transmission automatically selects a gear which is nearest to the current road speed	Why Why CVT? 'Conventional' automatic transmissions have a series of fixed gear ratios. The transmission automatically selects a gear which is nearest to the current road speed and throttle position, however, ideal gear matching is not often accomplished. In addition most automatic transmissions use a 'torque converter' to connect to the engine. Even if this is fitted with a 'lock up clutch' only an average of 90% engine power efficiency is achieved. There are no fixed gear ratios with the CVT technology. Nor does it have a power robbing torque converter. As its name suggests, it is seamless in operation, ranging from rest to full speed on one smooth jet-like operation. By continuously matching the ideal ratio to engine performance, the engine can be operated in a highly-efficient manner in D range or take advantage of S range for brisker performance or off-road conditions.
the transmission computer provides the right balance of oil pressure to each drum	How Technically, in a CVT conventional gears are replaced by two variable size drums and a steel drive belt. The flexible steel belt runs in a groove formed between the sides of each drum. The diameter of each drum is controlled by the transmission computer, applying or reducing oil pressure to the movable part of each drum. The drive pulley has low oil applied, and has expanded to allow the belt to run in a small diameter. In turn, the driven pulley has high oil pressure applied, forcing the belt outward around a larger diameter. This condition results in the driving pulley turning over four resolutions to the driven pulleys once. This is a low ratio (1st gear). In its highest ratio ('top gear'), high oil pressure is applied to the drive pulley and removed from the driven pulley. The drum diameters are now reversed so the driven pulley is turning faster than the driving pulley. In between these two positions, lowest to highest ratios, the transmission computer provides the right balance of oil pressure to each drum. This achieves the correct ratio to suit the prevailing road conditions and accelerator position. Drive mode selected etc.