剛看到一段Powershift的描述,對這棵新機絲稍覺安心了點,應該不會是Ford傳統的玻璃XX箱。 🙂 PowerShift is the result of a Ford-Getrag joint venture, a transmission that will be seen in Ford Motor Company products later in the decade. In gasoline applications, PowerShift promises a 12-percent fuel economy advantage over today’s four-speed automatic transmissions and provides capability to handle a whopping 332 lb-ft (450 nm) of torque in a compact package. 難怪新Focus汽油版的油耗也改進許多。😌 "A twin wet-clutch module replaces the traditional torque converter and operates using hydraulic actuation. This feature is similar to the clutch found on a typical manual transmission," said Ernie DeVincent, department manager for transmissions and drivelines in Ford Advanced Research and Engineering.
"However, manual transmissions or automated manual transmissions change gears by disengaging the clutch, which interrupts the flow of torque and can cause rough shifts," DeVincent said. "The PowerShift approach changes gears by power-shifting from one clutch to the other, giving smooth shift quality equal to a typical automatic transmission."
The PowerShift transmission uses a layshaft architecture, which also has more in common with manual transmissions than typical automatics, with gears arranged on two parallel shafts. Within the PowerShift transmission, one clutch connects to the odd gears (1, 3, 5), the other clutch to the even gears (2, 4, 6). The dual-clutch layshaft has better mechanical efficiency than conventional automatic transmissions by eliminating the torque converter and the drag losses of an open clutch. A typical four-speed FWD automatic transmission has approximately 68 percent mechanical efficiency (on the EPA fuel economy test), vs. 80 percent for a PowerShift transmission.
Combined with the Duratorq TDCi diesel, the PowerShift promises 5 percent better fuel economy than a conventional six-speed automatic transmission, and 6 percent better acceleration times.
Outstanding Diesel Powertrain
The PowerShift transmission makes an ideal partner for the Duratorq TDCi engine. Even efficient, lightweight turbochargers can induce a noticeable delay in torque rise on tip-in because of inertia – the so-called "turbo lag." A twin clutch transmission like the PowerShift offers an advantage because of its lower inertia compared with a typical torque converter, minimizing the effect of turbo lag. In addition, the diesel’s low-end torque will allow lower launch rpm, which results in a shorter duration of clutch slip at launch for quicker acceleration.
Diesel engines tend to have differently shaped horsepower and torque curves than gasoline engines, making it desirable to adjust the step size between transmission gears accordingly. Here again, the PowerShift transmission, like all layshaft-based transmissions, offers an advantage. Internal gear sets can be changed easily during development, allowing the efficiencies of common transmission architecture, while optimizing gear ratios for both engine types.
While the shifting is automatic, the PowerShift transmission on the Bronco concept also can be placed in manual mode, with sporty Formula 1-style shifting, using a pair of control paddles on the steering wheel.
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