Smartstream IVT
In internal combustion engine vehicles (ICEVs), the transmission serves an important role of situationally adjusting the engine RPM to allow controlled application of power. Appropriate shifting of gears can let the engine to continuously function at the desired range of high-efficiency, improving both performance and fuel economy. Recently, auto consumers have developed divergent preferences for vehicles with distinct acceleration performance and shifting ‘feel,’ and a variety of transmissions have emerged in the market to meet their needs. Hyundai Motor Group’s continuously variable transmission Smartstream IVT is one such entrant to the market.
Continuously variable transmissions (CVTs) have the structure in which two pulleys connected to the engine output shaft and the driveshaft are linked via a belt. The belt contracts and expands to alter the diameter of the pulleys, thus varying the gear ratio. Because they can continuously vary the gear speed, even from the lowest gear to the highest gear, CVTs is capable of setting the optimal engine RPM for maximal power output and efficiency.
In fact, thanks to this structure (as distinguished from standard 8-speed ATs), CVTs can theoretically set the optimum gear ratio down to the decimal point within the available range. As a result, they boast a 20 to 30% improvement in fuel economy over regular transmissions, not to mention allowing for a smooth ride without clunking from the shifting. This smoothness, though, is often misinterpreted by some drivers as “low in power,” and some even go further to state that it lacks of “driving fun that comes from shifting.” What’s more, there were some mechanical difficulties in the early versions as well: the belt could not withstand the engine’s power output for too long, causing durability issues. In other instances, the pulleys and the belt often slipped against each other, causing unwanted noise and worsened fuel economy.
Hyundai Motor Group’s Smartstream IVT is the next generation of CVT that has maximized its advantages and addressed the durability and ‘feel’ issues that plagued the original. It approximates the shifting feel of regular ATs by creating virtual shifting patterns that respond to the driver’s intent. In essence, the IVT is the CVT with virtual gear speeds—and it is an answer to those who found the CVT uninteresting to drive.
Moreover, the IVT uses not the typical metallic belt but a chain belt, the first of its kind on a similar transmission, that can better and longer withstand the power output from the engine. The chain belt, in addition, uses the belt’s tension to adjust the diameter of the pulley, a mechanism that eliminates the slippage that had been the cause of the noise and the fuel economy loss.
Conventional segmented steel belt CVT (Honda)
In internal combustion engine vehicles (ICEVs), the transmission serves an important role of situationally adjusting the engine RPM to allow controlled application of power. Appropriate shifting of gears can let the engine to continuously function at the desired range of high-efficiency, improving both performance and fuel economy. Recently, auto consumers have developed divergent preferences for vehicles with distinct acceleration performance and shifting ‘feel,’ and a variety of transmissions have emerged in the market to meet their needs. Hyundai Motor Group’s continuously variable transmission Smartstream IVT is one such entrant to the market.
Continuously variable transmissions (CVTs) have the structure in which two pulleys connected to the engine output shaft and the driveshaft are linked via a belt. The belt contracts and expands to alter the diameter of the pulleys, thus varying the gear ratio. Because they can continuously vary the gear speed, even from the lowest gear to the highest gear, CVTs is capable of setting the optimal engine RPM for maximal power output and efficiency.
In fact, thanks to this structure (as distinguished from standard 8-speed ATs), CVTs can theoretically set the optimum gear ratio down to the decimal point within the available range. As a result, they boast a 20 to 30% improvement in fuel economy over regular transmissions, not to mention allowing for a smooth ride without clunking from the shifting. This smoothness, though, is often misinterpreted by some drivers as “low in power,” and some even go further to state that it lacks of “driving fun that comes from shifting.” What’s more, there were some mechanical difficulties in the early versions as well: the belt could not withstand the engine’s power output for too long, causing durability issues. In other instances, the pulleys and the belt often slipped against each other, causing unwanted noise and worsened fuel economy.
Hyundai Motor Group’s Smartstream IVT is the next generation of CVT that has maximized its advantages and addressed the durability and ‘feel’ issues that plagued the original. It approximates the shifting feel of regular ATs by creating virtual shifting patterns that respond to the driver’s intent. In essence, the IVT is the CVT with virtual gear speeds—and it is an answer to those who found the CVT uninteresting to drive.
Moreover, the IVT uses not the typical metallic belt but a chain belt, the first of its kind on a similar transmission, that can better and longer withstand the power output from the engine. The chain belt, in addition, uses the belt’s tension to adjust the diameter of the pulley, a mechanism that eliminates the slippage that had been the cause of the noise and the fuel economy loss.
Conventional segmented steel belt CVT (Honda)