2018 MINI Cooper

FASTER GEARSHIFTS AND MORE FUN: DOUBLE CLUTCH TRANSMISSION IN THE MINI

•New for the MINI 3-Door Hatch, MINI 5-Door Hatch and MINI Convertible: 7-speed Steptronic automatic transmission with double clutch for extremely fast gear changes, a high degree of shift comfort and optimised efficiency.
As a brand well known for it's sporty character, MINI is set to further enhance it's reputation with the introduction of a new transmission to the range. Extremely fast gear changes, a high degree of shift comfort and optimised efficiency – just some of the benefits of the new 7-speed Steptronic automatic double clutch transmission available for the MINI 3-Door Hatch, MINI 5-Door Hatch and the MINI Convertible. Customers can now order this new transmission in conjunction with selected engine varients as an alternative to the standard 6-speed manual transmission. (posted on conceptcarz.com)




Design principle drawn from motor racing.
The design principle of the double clutch transmission has been adapted directly from motor racing. Just like on the race track, it allows MINI drivers to accelerate by enabling upward gearshifts without torque interruption. The driver can keep the accelerator pedel pressed down while the transmission control sets the shift points precisely - within just a fraction of a second the ideal engine speed is always available after the gearshift to ensure a continuous increase in speed.

This is possible due to the specific structure of the double clutch transmission. (posted on conceptcarz.com) It combines two partial transmissions in a single housing. The core element of the system consists of two oil-cooled wet clutches: one of these is responsible for the even transmission ratios (2, 4, 6) while the other is for the uneven ratios (1, 3, 5, 7) and reverse. During travel, one of the two clutches is open and the other is closed. They interact when the driver shifts up or down: opening one clutch activates closure of the second at the same time.

Transmission control always knows which is the right gear.
In order to have the appropriate gear ready for the next shift, the electronic control system of the new double clutch transmission permanently analyses the driver's intentions and the situation on the road. This analysis incorporates numerous data points, including the accelerator position, engine speed, road speed and MINI driving mode. As a result, fast gearshifts can be made to respond appropriately to sudden changes. If acceleration has to be unexpectedly interrupted, for instance, the double clutch transmission takes no more than a fraction of second to make the next gear down available instead of the next gear up.



In automatic mode, the system can be enhanced by linking the transmission control to the optional MINI Navigation System. The double clutch transmission control unit is then able to draw on navigation data to adapt its shift strategy to the road ahead. When approaching a sharp bend or junction, for example, a downshift is made early in order to make use of the engine braking effect for deceleration purposes. When passing through two bends in quick succession, the drive position engaged after downshifting is maintained in order to avoid any unnecessary shifting and ensure the ideal gear is available for powerful acceleration on exiting the bend.

Like a conventional converter system, the double clutch transmission also offers a crawl function that enables smooth set-off without needing the drivier to touch the accelerator pedal, thereby increasing comfort when manoeuvring or in slow moving or queuing traffic. The dual-mass flywheel with integrated centrifugal pendulum develops its positive effect when driving at low revs: it balances out rotational unevenness in the event of a sudden torque request, thereby promoting vibrational and acoustic comfort when accelerating out of the low engine speed range.

Optimised efficiency with engine start/stop function and coasting mode.
The 7-speed double clutch transmission electronic control system offers a wide range of progressive functions to increase the efficiency of the MINI. In order to avoid unnecessary consumption of fuel when stationary, the double clutch transmission also allows use of the engine start/stop function.

In addition, the coasting function is available in both the MID and GREEN driving modes. Here the drivetrain is decoupled as soon as the driver removes their foot from the accelerator pedal. This allows the MINI to roll along at idling speed – free of any engine braking effect, minimising fuel consumption. The coasting function can be adapted more precisely to the driving situation if the vehicle is fitted with the MINI Navigation System or Driver Assistance Systems. If there is a need to apply the brakes based on navigation data or camera images, for example, because the MINI is approaching a junction or another road user ahead, the coasting function is suppressed to make use of the engine braking effect.

Source - MINI