The British premium automobile manufacturer MINI highlights the sporty character of its current models in the small segment with a new type of transmission. Extremely fast gear changes, a high degree of shift comfort and optimised efficiency – these are the benefits of the 7-speed Steptronic automatic transmission with double clutch, available for the MINI 3 door,
Operating principle drawn from motor racing for enhanced driving fun on the road.
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 undertake highly dynamic acceleration manoeuvres by enabling upward gearshifts without torque interrupt. The driver can keep the accelerator pressed down while the transmission control sets the shift points so precisely within just a fraction of a second that 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. 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.
The 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 the accelerator position, engine speed, road speed and MINI driving mode.
The parallel opening and closing of the clutches makes acceleration and deceleration manoeuvres not just faster but also smoother. Acoustically, the gearshifts can only be perceived in the fast succession of rev changes – also to be seen in the abrupt movements of the tachometer needle. What is more, there are no load change reactions as are common in conjunction with manual transmissions.
Seven gears for increased riding fun and enhanced comfort.
The increase in drive positions as compared to the 6-speed manual transmission benefits both sporty flair and ride comfort. The seven gears of the double clutch transmission enable a broader spread of gears, thereby reducing the differences in engine speed between the various drive positions. Together with the direct engine link that is characteristic of the double clutch transmission, the small rev jumps make for particularly intense driving fun when accelerating.
Like a conventional converter system, the double clutch transmission also offers a crawl function that enables smooth set-off without activating the accelerator, thereby increasing comfort when manoeuvring or in stop-and-go 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 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.
In addition, the electronic control system of the 7-speed double clutch transmission offers a wide range of progressive functions to increase the efficiency of the MINI. In order to avoid unnecessary consumption of fuel when stopping at junctions, for example, the double clutch transmission also allows use of the engine start/stop function.