en.wikipedia.org/wiki/Direct-shift_gearbox
DSG controls
The direct-shift gearbox uses a floor-mounted transmission shift lever, very similar to that of a conventional automatic transmission.[10]The lever is operated in a straight 'fore and aft' plane (without any 'dog-leg' offset movements), and uses an additional button to help prevent an inadvertent selection of an inappropriate shift lever position.
双离合变速箱不使用单独的离合踏板进行档位切换，非常类似于AT变速箱。只需要通过下压油门踏板或者刹车踏板即可实现换档，并且在换档杆上有一额外的按钮，用以帮助防止无意的操作在不适合的档位之间切换（按下才可推动档杆，反之不行）。
P
P position of the floor-mounted gear shift lever means that the transmission is set in park. Both clutch packs are fully disengaged, all gear-sets are disengaged, and a solid mechanical transmission lock is applied to the crown wheel of the DSG's internal differential. This position must only be used when the motor vehicle is stationary. Furthermore, this is the position which must be set on the shift lever before the vehicle ignition key can be removed.
P档代表停车档。两个离合器都处于完全分开，所有的变速齿轮也处于没有啮合的状态，并且会有一个传动锁应用于变数箱。该档位只能而且必须在车辆停稳时使用。而且只有档位处于P档时才能移走点火钥匙。
N
N position of the floor-mounted shift lever means that the transmission is in neutral. Similar to P above, both clutch packs and all gear-sets are fully disengaged; however, the parking lock is also disengaged.
N档代表空档。和P档一样，此时两个离合器皆出于完全分离，所有的的齿轮都没有啮合。但是和P档不一样的是，此时变速箱的传动锁也是打开的。
D mode
Whilst the motor vehicle is stationary and in neutral (N), the driver can select D for drive (after first pressing the foot brakepedal). The transmission's reverse gear is selected on the first shaft K1,[3]and the outer clutch K2 engages at the start of the bite point. At the same time, on the alternate gear shaft, the reverse gear clutch K1 is also selected[2][3](pre-selected), as the gearbox doesn't know whether the driver wants to go forward or reverse. The clutch pack for second gear (K2) gets ready to engage. When the driver releases the brake pedal, the K2 clutch pack increases the clamping force, allowing the second gear to take up the drive through an increase of the bite point, and thereby transferring the torque from the engine through the transmission to the drive shafts and road wheels, causing the vehicle to move forward. Depressing the accelerator pedal engages the clutch and causes an increase of forward vehicle speed. Pressing the throttle pedal to the floor (hard acceleration) will cause the gearbox to "kick down" to first gear to provide the acceleration associated with first, although there will be a slight hesitation while the gearbox deselects second gear and selects first gear. As the vehicle accelerates, the transmission's computer determines when the second gear (which is connected to the second clutch) should be fully used. Depending on the vehicle speed and amount of engine power being requested by the driver (determined by the position of the throttle pedal),[4]the DSG then up-shifts. During this sequence, the DSG disengages the first outer clutch whilst simultaneously engaging the second inner clutch[2][3][4](all power from the engine is now going through the second shaft), thus completing the shift sequence. This sequence happens in 8 milliseconds (aided by pre-selection),[3][4]and can happen even with full throttle opening, and as a result, there is virtually no power loss.[2][4]
Once the vehicle has completed the shift to second gear, the first gear is immediately de-selected, and third gear (being on the same shaft as 1st and 5th) is pre-selected,[2][3][4]and is pending. Once the time comes to shift into 3rd, the second clutch disengages and the first clutch re-engages.[2]This method of operation continues in the same manner for the remaining forward gears.
Downshifting is similar to up-shifting but in reverse order, and is slower, at 600 milliseconds, due to the engine's Electronic Control Unit, or ECU, needing to 'blip' the throttle so that the engine crankshaft speed can match the appropriate gear shaft speed.[2][4]The car's computer senses the car slowing down, or more power required (during acceleration), and thus engages a lower gear on the shaft not in use, and then completes the downshift.
The actual shift points are determined by the DSG's transmission ECU, which commands a hydro-mechanical unit.[2]The transmission ECU, combined with the hydro-mechanical unit, are collectively called amechatronics[2]unit or module. Because the DSG's ECU usesfuzzy logic, the operation of the DSG is said to beadaptive;[dubious–discuss]that is, the DSG will "learn" how the user drives the car, and will progressively tailor the shift points accordingly to suit the habits of the driver.[citation needed]
In the vehicle instrument display, between thespeedometerandtachometer, the available shift-lever positions are shown, the current position of the shift-lever is highlighted (emboldened), and the current gear ratio in use is also displayed as a number.
Under "normal", progressive and linearaccelerationand deceleration, the DSG shifts in asequentialmanner; i.e., under acceleration: 1st → 2nd → 3rd → 4th → 5th → 6th, and the same sequence reversed for deceleration. However, the DSG can also skip the normal sequential method, by missing gears, and shift two or more gears.[3]This is most apparent if the car is being driven at sedate speeds in one of the higher gears with a light throttle opening, and the accelerator pedal is then pressed down, engaging thekick-downfunction. During kick-down, the DSG will skip gears,[10]shifting directly to the most appropriate gear depending on speed and throttle opening. This kick-down may be engaged by any increased accelerator pedal opening, and is completely independent of the additional resistance to be found when the pedal is pressed fully to the floor, which will activate a similar kick-down function when in Manual operation mode. The seven-speed unit in the 2007 Audi variants will not automatically shift to 6th gear; rather, it stays at 5th to keep power available at a high RPM while cruising.[citation needed]
When the floor-mounted gear selector lever is in position D, the DSG works in fully automatic mode,[3][5]with emphasis placed on gear shifts programmed to deliver maximum fuel economy.[3][10]That means that shifts will change up and down very early in the rev-range. As an example, on theVolkswagen Golf Mk5 GTI, sixth gear will be engaged around 52 km/h (32 mph), when initially using the DSG transmission with the default ECU adaptation; although with an "aggressive" or "sporty" driving style, the adaptive shift pattern will increase the vehicle speed at which sixth gear engages.
S mode
The floor selector lever also has an S position.[2]When S is selected, sport mode[2]is activated in the DSG. Sport mode still functions as a fully automatic mode,[3]identical in operation to D mode, but up shifts and downshifts are made much higher up the engine rev-range.[2][3][10]This aids a more sporty driving manner,[2]by utilising considerably more of the available engine power, and also maximising engine braking. However, this mode does have a detrimental effect on the vehicle fuel consumption, when compared to D mode. This mode may not be ideal to use when wanting to drive in a sedate manner; nor when road conditions are very slippery, due to ice, snow or torrential rain — because loss of tire traction may be experienced (wheel spin during acceleration, and may also result in road wheel locking during downshifts at high engine rpms under closed throttle). On 4 motion or quattro-equipped vehicles this may be partially offset by the drivetrain maintaining full-time engagement of the rear differential in S mode, so power distribution under loss of front-wheel traction may be marginally improved.
S is highlighted in the instrument display, and like D mode, the currently used gear ratio is also displayed as a number.
R
R position of the floor-mounted shift lever means that the transmission is in reverse. This functions in a similar way to D, but there is just one reverse gear. When selected,R is highlighted in the instrument display.
Manual mode
Additionally, the floor shift lever also has another plane of operation, formanual[3][5]mode, with spring-loaded+and−positions. This plane is selected by moving the stick away from the driver (in vehicles with the driver's seat on the right, the lever is pushed to the left, and inleft-hand drivecars, the stick is pushed to the right) when inDmode only. When this plane is selected, the DSG can now be controlled like amanual gearbox, albeit only under asequential shift pattern.
In most (VW) applications, the readout in the instrument display changes to6 5 4 3 2 1, and just like the automatic modes, the currently used gear ratio is highlighted or emboldened. In other versions (e.g., on the Audi TT) the display shows justMfollowed by the gear currently selected; e.g.,M1,M2, etc.
To change up a gear, the lever is pushed forward (against a spring pressure) towards the+, and to change down, the lever is pulled rearward towards the−. The DSG transmission can now be operated with the gear changes being (primarily) determined by the driver. This method of operation is commonly calledtiptronic.[2]In the interests of engine preservation, when accelerating in Manual/tiptronic mode, the DSG will still automatically change up just before theredline, and when decelerating, it will change down automatically at very low revs, just before the engineidle speed(tickover). Furthermore, if the driver calls for a gear when it is not appropriate (e.g., requesting a downshift when engine speed is near the redline) the DSG will not change to the driver's requested gear.[3]
Current variants of the DSG will still downshift to the lowest possible gear ratio when thekick-downbutton is activated during full throttle whilst in manual mode. In Manual mode this kick-down is only activated by an additional button at the bottom of the accelerator pedal travel; unless this is pressed the DSG will not downshift, and will simply perform a full-throttle acceleration in whatever gear was previously being utilised.
