GM - Automatico 10 rapporti Hydra-Matic: più veloce di un PDK

crabble · 11 Maggio 2016

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Chevrolet Says The Camaro ZL1's 10-Speed Automatic Is Faster Than Porsche's PDK

Chevrolet’s Camaro ZL1 is available with an all-new 10-speed automatic transmission called Hydra-Matic. The Bowtie brand says their new automatic unit is faster than a dual-clutch, and comes with the optimal gearing spread for best performance and efficiency.

Chevrolet’s Camaro ZL1 is claimed to be the world’s first volume production car to be available with a 10-speed automatic gearbox, an accomplishment which appears to be accurate, as there is no another passenger car with such a transmission available today.

While some automakers provide their sports cars with dual-clutch automatic transmissions or sequential-manual units, General Motors chose a conventional torque converter solution, but utilized a new design from scratch to develop their fastest gearbox ever.

General Motors engineers focused on a gearing combination that would allow the supercharged LT4 V8 engine to be in the best rpm range in both corners and straight lines. Furthermore, Chevrolet claims the automatic has been optimized to maintain optimum engine speed at almost all vehicle speeds, particularly when exiting a corner on track.

The transmission has four gearsets and six clutches. Out of these, two are brake clutches, and four are rotating ones. Compared to the eight-speed automatic on the Camaro, it only has one more clutch, in spite of the fact that it features two extra gears.

Naturally, the top gear ratio is lower than the eight-speed automatic on the Camaro, which provides a lower rpm range at highway speeds, an element which improves fuel economy when the car is in regular driving conditions.

Chevrolet’s internal testing revealed that a Camaro ZL1 with a 10-speed automatic transmission is faster than the equivalent Porsche PDK dual-clutch unit. While not mentioned in the press release, we presume General Motors has benchmarked it with a comparable Porsche 911.

According to Chevrolet, the upshift action from 1st gear to 2nd is 36% quicker on the Camaro’s 10-speed automatic than on Porsche’s PDK unit. The PDK transmission from Porsche is only 27% slower than Chevrolet’s 10-speed automatic on the shift from second to third gear.

Meanwhile, the shift from third to fourth is 26% faster on Camaro ZL1’s 10-speed gearbox than on the Porsche PDK, Chevrolet claims.

http://www.autoevolution.com/news/chevrolet-says-the-camaro-zl1-s-10-speed-automatic-is-faster-than-porsche-s-pdk-107388.html#

RVC · 12 Maggio 2016

Bravi, se è come dichiarato hanno fatto un gran lavoro sulla trasmissione.

***J-Gian*** · 21 Maggio 2016

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DETROIT – Engineers for the new 10-speed automatic transmission available in the 2017 Chevrolet Camaro ZL1 built on the experience of previous, critically acclaimed Hydra-Matic multispeed transmissions to push its performance, refinement and efficiency advantages to a new threshold.

The 10-speed is an all-new design – and the first-ever application in a car – with a wider, 7.39 overall gear ratio spread, that enables the ZL1’s supercharged engine to remain at optimal engine speeds during upshifts.

“With world-class shift times on par with the world’s best dual-clutch transmissions and the refinement that comes only from a true automatic, the 10-speed delivers incomparable performance on and off the track,” said Dan Nicholson, vice-president, GM Global Propulsion Systems. “It also leverages the experience of our other multispeed transmissions to deliver that performance with greater efficiency as its use expands into other vehicles.”

The wider overall ratio enables a lower numerical top gear ratio – an attribute that reduces engine speed on the highway, which contributes to greater fuel efficiency than a comparable eight-speed transmission. Improvements in spin loss complement the optimized gearing, further enhancing efficiency.

And while the Camaro ZL1 will be the first GM vehicle to offer the new 10-speed automatic, designed for rear-wheel-drive applications, it will be available in eight additional vehicles by 2018.

Additional highlights:

Creative packaging – The 10-speed is approximately the same size as the six- and eight-speed transmissions, minimizing changes to vehicle interfaces.

Quicker shifts than a dual-clutch transmission – Testing has shown faster upshift times than the Porsche PDK dual-clutch transmission. In fact, the 1-2 upshift is 36-percent quicker than the PDK, while the 2-3 and 3-4 upshifts are 27-percent and 26-percent quicker, respectively.

Reduced spin losses – Thanks to only two non-applied clutches – the same number as the eight-speed – as well as other design features, the 10-speed automatic has lower friction that contributes to greater fuel efficiency over GM’s six- and eight-speed automatics. New ultra-low viscosity transmission fluid also reduces friction, while an internal thermal bypass allows the transmission to warm up faster – attributes that enhance fuel efficiency

GM-developed controller – It is the latest transmission to use an all-new, GM-developed control system, with performance calibrations tailored specifically for different vehicles.

Architectural features and packaging
Thousands of hours of computer-aided engineering analyses were made during the development of the Hydra-Matic 10-speed transmission, driving a comparatively compact design envelope comparable to the eight-speed automatic.

A one-piece aluminum case with an integral bell housing helps reduce weight and enhance powertrain stiffness, while a unique 260mm, integral turbine clutch torque converter design reduces complexity and helps make the converter thinner, which contributes to the transmission’s packaging.

The 10-speed has four simple gearsets and six clutches: two brake clutches and four rotating clutches. That’s only one more clutch than the eight-speed, despite having two more forward gears, contributing further to the compact packaging, while also improving spin losses to enhance fuel efficiency.

A unique triple-clutch assembly in the middle of the 10-speed’s architecture is a primary enabler for packaging 10-speed content in the same space as GM’s six- and eight-speed transmissions.

The 10-speed also features a variable-displacement vane pump, which optimizes transmission fluid pressure, based on speed and load, to enhance efficiency.

7.39 ratio spread and faster upshifts
The new 10-speed’s greater overall performance and efficiency are due primarily to its wider 7.39 overall gear ratio spread, which enhances off-the-line performance with a more aggressive first gear ratio than GM’s eight-speed automatic. Smaller steps between the gears also help the engine maintain the optimal speed for maximum power at almost all speeds, especially when exiting a corner on a track.

Adaptive shift controls such as Performance Algorithm Shifting and Driver Shift Control enhance performance driving. Performance Algorithm Shifting (PAS) monitors how assertively the driver is using engine output to determine at what engine speed to upshift or downshift. Driver Shift Control allows the driver to shift the transmission via the steering wheel-mounted paddle shifters. Electronic safeguards prevent over-revving if the wrong gear position is selected, but relies on the driver to make upshifts or downshifts.

Gear changes are mainly executed with clutch-to-clutch action, where an “on-coming” clutch is engaged and an “off-going” clutch is released in a precise manner to achieve the ratio change. Certain key shifts, however, are made with a freewheeling action, such as 3-1 downshifts, where a plate clutch is actively disengaged while a mechanical freewheeler clutch automatically engages with optimum synchronization.

The torque converter is 260mm in diameter and features a lock-up clutch. It also uses electronic controlled capacity clutch (ECCC) technology, which employs a small, regulated amount of slip to dampen out engine pulses for a smoother running drivetrain, especially during shifting.

Reduced spin losses and new transmission fluid
Friction-reducing design features, including all-new ultra-low viscosity transmission fluid, internal thermal bypass, minimal number of non-applied clutches and other lower mechanical spin losses, contribute to the 10-speed’s effect on improved vehicle efficiency.

The low-viscosity fluid helps reduce fraction across the full temperature operating range, which enhances fuel efficiency. Additionally, the internal thermal bypass allows the transmission to warm up faster to its optimal operating temperature, further contributing to fuel efficiency.

GM control system
World-class shift time quickness and responsiveness are accomplished by leveraging the base transmission hardware in concert with GM exclusively developed algorithms, software and calibrations. An externally mounted electronic control module executes millions of controls instructions every second.

General Motors Co. (NYSE:GM, TSX: GMM) and its partners produce vehicles in 30 countries, and the company has leadership positions in the world's largest and fastest-growing automotive markets. GM, its subsidiaries and joint venture entities sell vehicles under the Chevrolet, Cadillac, Baojun, Buick, GMC, Holden, Jiefang, Opel, Vauxhall and Wuling brands. More information on the company and its subsidiaries, including OnStar, a global leader in vehicle safety, security and information services, can be found at http://www.gm.com