Diesel Version of Honda Civic Gets Automatic Transmission
For the first time in its history, Honda engineers decided to combine a diesel Civic model with an automatic gearbox. The Civic model, recently released for the European car market, has an automatic gearbox paired with an engine operating on “heavy oil”. Previously, Honda Civic was offered only as petrol running versions equipped with the CVT.
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The powertrain of the new Civic includes the i-DTEC diesel engine operating in pair with a new turbine. The engine power equals to 120 horsepower, while the torque capacity reaches up to 340 Nm. The engine in the new Civic operates with the 9-speed automatic gearbox ZF 9HP. It is noteworthy that it is not the first time when Honda employs the 9-speed automatic gearboxes in its cars. This gearbox was installed on the previous generation of SUVs Honda CR-V, Pilot, а as well as on models Odyssey, UR-V and Avancier. The main peculiarity of the ZF 9HP is that it is capable of gear shifting by “skipping gears” (for example, shifting from 5-th to 9-th speed) for improved fuel economy.
i-DTEC diesel engine
Thanks to matching the diesel engine with the automatic gearbox, the European Civic became capable of accelerating from 0 to 100 km/h in 11 seconds with an average fuel-consumption rate equal to 4,1L per 100 kilometers. The new 1.6 i-DTEC engine from Honda is one of the first engines which will be officially tested with the help of the Real Driving Emission (RDE) method. This procedure helps to check the level of NOx emissions.
ABOUT ZF 9HP
The automatic transmission ZF 9HP differs markedly
from its predecessor 8HP. First of all, this transmission is intended for cars with
a cross-mounted engine, in other words, mainly for front-wheel drive cars. Secondly,
this transmission includes many technical innovations.
The ZF 9HP has 4 planetary gear sets (the same number as in 8HP), but in the 9HP they are arranged in chessboard order. Thanks to this design solution, engineers made the gearbox incredibly compact— 367 mm in length, it is only 6 mm longer than the 6-speed automatic transmission installed on Evoque. Moreover, the 9HP is smaller in weight by 7,5 kg! Despite the fact that 9HP is an actual automatic transmission, not a dual-clutch version, it has no torque converter. The torque converter on the 8HP was replaced with a multi-disc hydraulic clutch, while on the 9HP engineers came up with the block consisting of 2 cam clutches.
Great presentation video about ZF
9HP
The maximum fuel economy in the 9HP is achieved due to the fact that the top gear has a high gear ratio equal to 9,84 (while in the 6-speed version this parameter amounts to only 6,04), thus the car can travel with the RPM rate equal to 1000. Moreover, thanks to high number of gears the electronics can keep the RPM rate within the optimal range. This transmission can be installed on FWD as well as on, AWD cars. The all-wheel drive version has the AWD Disconnect module which actuates the rear axle at the command of the electronics — it helps to save another 5% of fuel compared to the standard version. In hybrid cars the block of cam clutches can be replaced with an electric motor.
And finally, ZF engineers replaced the “mechatronic” control module with the electronic control unit EGS. It is the first time when ZF specialists independently developed a program for the control unit. This unit has a 30% performance margin, which will allow the implementation of the “shift-by-wire” technology (electronic gear shifting control) in the future.
