New 2014 Toyota Corolla brings Valvematic, new CVT to North America; up to >40 mpg highway
7 June 2013
|2014 Toyota Corolla LE Eco. Click to enlarge.|
Toyota unveiled the 2014 Toyota Corolla—the 11th generation of the car. With nearly 40 million units sold, the Toyota Corolla is the world’s best-selling car nameplate; this year marks its 47th year on the market.
The 2014 Corolla is available in four distinct grades: L, LE, S, and the new LE Eco grade. The LE Eco grade is differentiated by a more efficient 140-horsepower, 1.8-liter engine with Valvematic technology; improved aerodynamics; and low rolling resistance tires. The Corolla Eco-badged models will achieve an estimated highway fuel economy rating of more than 40 mpg (5.88 l/100km) due to to the new Valvematic engine combined with a newly developed Continuously Variable Transmission (CVT).
The 2014 Corolla offers two 1.8-liter, all-aluminum four-cylinder engines. The base 1.8-liter unit with VVT-i is available on the L, LE, and S grades and is rated at 132 hp (98 kW). The Corolla’s new LE Eco trim level is equipped with a 1.8-liter engine with Valvematic—a further development of VVT-i—a valve train technology which appears for the first time in North America with Corolla.
Valvematic offers a broader range of continuously variable valve timing (lift and phasing) to provide optimal intake valve (not on exhaust side) operation relative to engine demands. Valvematic offers more than a five-percent improvement in fuel economy and engine output (140 hp / 104 kW).
The 2014 Corolla also offers improved fuel economy due to its advanced Continuously Variable Transmission. This CVTi-S (i for intelligent, S for shift), which will be available on the LE, S, and LE Eco Corolla models, features several enhancements to improve its efficiency and driving performance with discrete shift points that help create a sensation more similar to a traditional hydraulic automatic transmission.
While the efficiency and reduced weight inherent in a pulley-type CVT would seem an ideal solution for vehicles emphasizing fuel efficiency, the characteristic CVT “rubber band” driving sensation of the engine winding to its power band upon acceleration has earned detractors.
With Corolla’s new CVTi-S, Toyota’s engineers improved the drivability of the new Corolla by adapting discrete stepped “gears” or shift points, into the car’s acceleration and deceleration curves. The Corolla’s new CVTi-S even mimics the familiar characteristics of hydraulic automatics creating a sense of positive shift engagement. On the Corolla S trim, up to seven shift-points can also be manually actuated from the shift gate or steering wheel paddle shifters.
As the first pulley-style CVT product offered by Toyota in North America, the engineering effort prioritized making the new CVTi-S’ operation and power application more appealing and familiar to North American drivers. Corolla’s engineers maximized the fuel saving design inherent in a pulley CVT while enhancing its operation to provide a more “direct feel” to pedal inputs through careful analysis of traditional automatic transmission operation. The new CVTi-S will provide a more linear connection between pedal effort and acceleration feel compared to previous CVT designs.
Toyota engineers addressed challenges presented by typical CVT design such as the high level of hydraulic pressure CVT’s require for operation, and the optimization of the pulley ratio range to offer the best performance and fuel economy.
Typically, CVT hydraulic-fluid pumps are driven at the same rate as engine speed; as a result, the pump wastes considerable effort, hurting transmission efficiency at higher engine speeds as the pump moves more fluid than necessary to lubricate and sandwich the CVT’s belt. With this new CVTi-S, hydraulic pressure was reduced to an optimal point to protect against belt slippage, while conserving drive effort to limit excess pumping losses.
The Corolla’s new CVTi-S is fitted with an oil pump that features a coaxial 2-port design that enables a 25% reduction in pump drive torque compared to other pump designs, and results in a greater efficiency with its reduction in parasitic engine loss.
|The Corolla’s new CVT maximizes the difference between the pulley sizes without an increase in the size of exterior case to achieve a speed ratio range of 6.3, which helps both fuel efficiency and acceleration. Click to enlarge.|
For a belt-driven CVT, the range of speed ratios is determined by the diameters of the input and output pulleys. The greater the disparity in size between these two pulleys, the greater the range of gear ratios, efficiency and performance the transmission can offer. The clearances within the Corolla’s CVTi-S exterior casing and between internal components have been enhanced to better accommodate the most optimally sized pulleys within the compact transmission case.
The CVTi-S offers a forward gear ratio range of 0.396 to 2.480, which works well for acceleration, cruising speeds, and fuel-conscious driving with a 4.761 final drive ratio. The new CVTi-S includes a transmission fluid warmer is used to help get fluid to optimal temperature faster.
The Corolla’s new CVTi-S is uses a lower viscosity CVT fluid that protects all of the transmission’s internal parts while helping reduce parasitic loss to enhance efficiency and performance. The CVTi-S also offers extremely quiet operation from a compact, lightweight case design that adds reinforcing ribs and an optimal shape to help suppress vibration and noise.
Corolla models equipped with CVTi-S offer the capability of either an ECO or SPORT driving mode. On the Corolla LE Eco, the ECO driving mode makes accelerator control become non-linear to suppress the vehicle’s response to choppy driving and contain acceleration from standing start to help reduce fuel consumption. The accelerator pedal’s communication is the same as Normal-mode after 50% throttle. In ECO mode, the air conditioning operation is controlled in the interest of efficiency with compressor power reduced, the utilization of recirculation mode, and extra time allowed to attain a desired interior cabin temperature.
As equipped on the Corolla S, the new CVTi-S offers a SPORT mode that helps deliver a more dynamic driving experience with software tuning that alters shift points, creating transmission behavior during acceleration that enhances the sporty character of the S-grade. SPORT mode is not a track-focused mode, but rather a transmission setting that, along with unique electric power steering programming, helps create a sportier driving sensation during normal road and freeway driving.
On the Corolla S equipped with CVTi-S, steering wheel mounted paddle shifters allow drivers to make fast, sequential, stepped shifts through “7-speeds” to help enhance the driving experience. The Corolla S console shifter also offers a manual gate (M-position) that also allows drivers to make brisk upshifts or downshifts using the shift lever. The next shift step will automatically be engaged if the engine revolutions become high enough or down shifted if they become low enough. The M mode activity is displayed in the black and white display of the Corolla S combination meter. The Corolla’s Sport mode was developed and evaluated on roads within the key global markets to help ensure a more energetic drive across a broad range of conditions.
The base model Corolla L is offered with a four-speed automatic transmission or a six-speed manual transmission. The six-speed manual is also available in the Corolla S.
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