The performance of Lexus’ hybrid vehicles should be evaluated based on this claim: maximum efficiency no matter the road conditions.
The Lexus hybrid’s smooth coupling of its gasoline and electric motors with its electronically-controlled continuously variable gearbox, or E-CVT, provides a means of fulfilling this promise.
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What is E-CVT?
The intelligent transmission E-CVT has access to an endless number of gear ratios. It chooses the best (most efficient) gear ratio at that specific moment by continuously analyzing the vehicle’s speed, the road’s circumstances, the engine’s power, and the driver’s input.
When that time has passed, the clever arrangement of planetary gears visible in the rendering above allows it to seamlessly and imperceptibly shift to the next ratio. This setup is fundamentally different from the drive belt and conical pulley arrangement of more conventional continuously variable transmissions.
Why is E-CVT ideal for petrol-electric hybrids?
The engine may run at its fastest speed to either drive the automobile or charge the batteries without being constrained by fixed gear ratios. Additionally, the twin-input E-CVT can be utilized to direct propulsion from the electric motors to the wheels in place of the gasoline engine if the computer determines that it is not necessary to keep it running for a while.
The transmission improves driver engagement in two ways when available. First off, models with an E-CVT system sequential function give the impression of manually shifting gear ratios by ensuring a better fit between increases in engine and vehicle speed. Additionally, stepped engine braking force is delivered using this during acceleration.
Second, models having an E-CVT sport mode that increases engine speed more quickly during acceleration alter the perception of dynamic performance. This is seen in the diagram below.
We are confident that E-CVT fulfills its promise of efficiently transferring propulsion and performance to the driving wheels as a crucial component of the Lexus Hybrid Drive experience. Why not give it a shot?
eCVT is it automatic?
Since the driver is not required to physically engage the clutch or shift between the forward speeds, a CVT is technically an automatic gearbox. However, there are important distinctions between the two in terms of both form and function.
A CVT does not have a predetermined number of preset gears like a standard automatic (or manual transmission, for that matter). Instead, it employs an infinite number of gear ratios to take into account the driving habits and environmental factors at any particular time. A CVT transmission is frequently referred to as “single-speed” or “shiftless” since it enables smooth shifts without any hard shift points.
A CVT uses two opposed cone-shaped pulleys with a chain or belt running between them to accomplish this unlimited gear ratio flexibility. This arrangement is quite comparable to how a chain moves over a bicycle’s gears.
The driveshaft and drive wheels get power from one cone, which is connected to the engine’s output shaft. The chain or belt moves up and down the sides of the two cones as a result of changing gear ratios as the pulleys move closer and farther away. Depending on the amount of power required, this movement changes the diameter of the chain or belt, which changes the gear ratio. While the car is moving, these continuous real-time alterations take place.
What distinguishes an electronic CVT from a conventional CVT?
When accelerating in a car with a CVT, the driver presses on the gas pedal, and the CVT makes adjustments to maintain the engine running at its most productive rpm.
Instead, an eCVT regulates the speeds of planetary gearset parts using electric motor/generators.
How does the Toyota hybrid transmission function?
Early HSD on a Toyota 1NZ-FXE engine, sectioned and highlighted (on the left) (right). The ICE-MG1-MG2 Power Split Device HSD for Generation 1 and Generation 2 is displayed.
The HSD system from Toyota uses an electromechanical mechanism in place of a typical geared transmission. The complete speed range of the vehicle must be used to move the wheels since an internal combustion engine (ICE) produces power most effectively across a narrow speed range. In a typical car, the geared transmission transmits the wheels’ many distinct engine speed-torque demands. Both manual and automatic geared transmissionseither with a clutch or a torque converterallow the engine and the wheels to spin at various rates. The transmission mechanically transfers virtually all of the available power to the wheels, which rotate at a pace distinct from the engine, by a factor equal to the gear ratio for the currently selected gear. The driver can control the speed and torque produced by the engine using the accelerator. The driver can only select from a small number of “gears” or gear ratios, usually four to six. The engine crankshaft must rotate at rates where the ICE is less efficient, or when a liter of fuel produces less joules, due to this constrained gear-ratio configuration. By limiting either the tachometer RPM rate or the engine noise in relation to the real speed, one can determine the ideal engine speed-torque requirements for various vehicle driving and acceleration scenarios. Due to the engine’s coupling to a geared transmission, manufacturers have few alternatives for increasing an engine’s efficiency, durability, or longevity as well as reducing the size or weight of the engine when it must run effectively over a wide RPM range. Because of this, an engine-engine generator’s is frequently smaller, more effective, more dependable, and has a longer lifespan than an engine made for a car or another variable-speed application.
A continuously variable gearbox, on the other hand, enables the driver (or the car’s computer) to efficiently choose the best gear ratio needed for any desired speed or power. There is no set of gears that the transmission must use. Due to the absence of a limitation, the engine can run at its ideal brake-specific fuel consumption. When accelerating or charging batteries, an HSD vehicle will normally run the engine at its most efficient level, shutting it down completely when less power is needed.
An HSD transmission, like a CVT, continuously modifies the effective gear ratio between the engine and the wheels to keep the engine running while the wheels accelerate faster. For this reason, when categorizing the transmission type for standards specification lists or regulatory purposes, Toyota refers to HSD-equipped vehicles as having an e-CVT (electronic continuously variable transmission).
What does eCVT in cars mean?
The electronic control system has an intriguing function where it monitors the driver’s behavior and adjusts the engine and transmission’s interface to maximize efficiency and performance. This results in a 10% fuel savings compared to a standard four speed automatic transmission. The selector lever used by the ECVT is remarkably similar to that of a typical automatic transmission. When D is engaged, the transmission will be running at the best ratio for the intended engine speed, allowing the driver to accelerate away. In general, ECVT vehicles accelerate from a stop far more quickly than their manual equivalents.
The ECVT gives a very wide ratio span while operating, roughly comparable to a six-speed manual transmission. Theoretically, assuming the engine is running at the right speed and load for the particular road speed, this should offer outstanding fuel economy. Unfortunately, frictional losses in the gearbox use a lot of energy; as a result, ECVT cars actually have a fuel efficiency that is roughly 5% worse than that of cars with identical manual transmissions. 25.29.1.
Is an automatic or CVT better?
When compared to a conventional automatic, a CVT may offer a smoother driving experience depending on the car and the driver. One of the biggest benefits of having a CVT, according to Carfax, is that they frequently use less fuel than a standard automatic.
Do CVTs outpace automatics in speed?
The main distinction between an automatic transmission and a continuously variable transmission (CVT) is that an automatic transmission uses hydraulic power to shift gears and cause the engine to operate at various speeds and outputs, whereas a CVT essentially has one gear and one speed and uses a pulley system.
The standard automatic transmission has its supporters who like its capacity to handle more engine power, longer lifespan, and the sharp shifts you can feel when the car changes levels.
Those who favor CVTs claim that the CVT improves fuel efficiency, prevents excessive engine wear, and smooths out acceleration.
How a Continously-Variable Transmission (CVT) Works:
Continuously variable transmissions don’t have any gears, in contrast to traditional automatic transmissions. A CVT substitutes two pulleys in the form of cones. The engine is connected to one pulley, while the remainder of the transmission is attached to the other. It provides the wheels with power. The two pulleys are connected by a steel or composite belt.
Depending on how much engine power the wheels require, the pulleys’ widths adjust. The size of one pulley decreases as the other one increases. The CVT’s version of having distinct gear ratios is shown by the large and small widths. Where the pulley rests on the cone is influenced by lower or higher RPMs. A CVT-powered vehicle may accelerate with power, smoothness, and efficiency thanks to this design.
Vehicles Using CVTs
Compared to European and local automakers, Japanese automakers often use CVT gearboxes more frequently. However, as cars become more fuel-efficient, their appeal is growing globally. Nissan, Mitsubishi, Subaru, and Subaru automobiles and SUVs frequently have CVTs. More CVTs are now available in Toyota and Honda’s vehicles. The company’s models that use the technology include the Honda Accord and Civic.
Check the automaker’s website or a printed vehicle brochure to find out what kind of transmission is in a certain car. Check the window sticker to see if it’s a new car. Research and product evaluation may be especially important for used autos.
Variations on CVTs
Not all CVTs are created equal. One variant is a distinct, less popular CVT design that uses rollers and discs. For instance, the 2021 Subaru Ascent features an interpretation that gives drivers a feeling akin to a traditional automatic. The Ascent’s eight pre-programmed shift locations on the pulley system provide the impression that the automobile is changing gears. Drivers can “change gears” manually or automatically by utilizing the gear lever or paddle shifters.
The Toyota Corolla of 2021 has a unique system with a first gear that resembles a manual transmission. It is referred to as a “launch gear” as it manages the car’s early acceleration. Once it exceeds 25 mph, the transmission enters the continuously variable transmission mode. According to Toyota, the vehicle can accelerate more powerfully and smoothly right away thanks to its launch gear.
Pros of CVT vs Automatic Transmission
The advantage of the CVT when contrasting it with automatic transmission technology is its capacity to alter its gear ratio as the engine speed changes continually. It denotes constant peak performance from the engine. There are what seems like countless possible gear ratios.
Because of its smoothness and adaptability, a CVT can extract the most horsepower possible from a small engine, providing drivers with speedier acceleration than typical automatic gearboxes. To benefit from this increase in power, automakers like Nissan, Mitsubishi, and Hyundai outfit their four-cylinder motors with CVTs.
Without interruptions from gear changes, a continuously variable gearbox offers smooth acceleration. For overtaking slower moving vehicles or ascending steep hills, CVTs provide additional power and speed. As with traditional automatic transmissions, drivers do not have to worry about jerky or bouncy downshifting or “hunting” for the right gear.
The engine speed range may be controlled, which makes CVTs more efficient. They are also lighter than standard automatic transmissions. Hybrid vehicles frequently use them since they can typically achieve superior fuel economy in cities and while traveling on the highway. For instance, the 2021 Toyota Prius achieves astonishing ratings of 54/50/52 mpg city/highway/combined. These numbers greatly beyond what is typical for an automobile. Gas efficiency would undoubtedly be affected if the Japanese company used an automatic in the Prius.
Regarding the driving experience, several motorists claim that compared to conventional automatic transmissions, the ride in cars with CVTs is remarkably smooth.
Cons of CVT vs. Automatic
Some motorists miss the automatic transmission’s acceleration and shifts. As with traditional automatic gearboxes, there are no sounds or sensations as the car shifts through the ratios. With a CVT, the engine achieves the same speeds, but all you hear is a quiet humming or droning. As a result, it might not have the same sporting vibe.
The maintenance of a transmission is different from that of an automatic transmission. Cars using CVTs require particular parts, transmission fluid, and oil. If you visit an independent retailer, it might also be necessary to have the vehicle serviced by a mechanic who is knowledgeable with the technology. Owners of vehicles with CVTs discover that the cost of transmission repair is higher than the cost of automatic transmission repair or replacement. And part of the increased cost is due to the fact that CVT specialists are needed for the repairs.
Owners have also frequently reported an abrupt lack of acceleration and transmission overheating. As a result of excessive stretching, wear, or full failure, the belts can cause jerking, slippage, and shuddering in the drivers. According to some complaints filed against car manufacturers, transmission repair work performed at the service center did not resolve the issue.
Popularity of CVTs
Finding a car with an automatic transmission is getting more and more challenging as more and more automakers are switching to CVTs. However, some producers are abandoning CVTs in favor of conventional automatic transmissions, as shown in the 2022 Nissan Pathfinder and Infiniti QX60.
The decision between an automatic and CVT is largely a question of preference. You could like a traditional automatic transmission’s distinct sounds and driving experience. The CVT can appeal to you if higher gas mileage is important.
To choose what is best for you, do your homework and do a test drive at the dealership.
What Does a Transmission Do?
Fundamentally, a gearbox is a device that allows an automobile’s engine to transfer power to the axles and wheels. Transmissions come in a variety of shapes and sizes, but they always share gears. Additionally, each transmission gear has a unique ratio.
The various ratios are engaged when transmissions are automatically or manually moved into different gears. It enables the vehicle to change its speed without the engine having to work too hard.
In the 1960s, continuously variable gearboxes made their debut. However, hybrid vehicles like the Honda Insight and Toyota Prius helped them gain popularity across the globe in the early 2000s. Drivers must take into account additional factors when using this transmission type, which has advantages and disadvantages.
How Manual vs. Automatic Transmissions Work
When operating a vehicle with a manual gearbox, such as a sports car, you shift between gears using the gear shift lever, often known as a stick shift, on the console of the vehicle. One to six gears are numbered, although there is a maximum of ten.
You shift the gear shifter into the next higher gear or lower gear when the engine’s revolutions per minute (RPM) rise or fall. The car accelerates or slows down as a result of this movement. To shift gears, you must squeeze the clutch, a third pedal. So that you can engage the gears, the clutch temporarily keeps them stationary.
In recent years, standard automatic gearbox cars have become more popular than manual transmission cars. Autonomous transmissions simplify the learning process considerably. They take less concentration when driving and put less strain on the engine. However, some ardent drivers swear by manuals.