9. Automatic transmissionThe car can be equipped with the automatic transmission or a box with stepless gear shifting of Multitronic.
The box can be removed without removal of the engine. It is necessary to remove a box at its replacement or repair. It is not recommended to make repairs of a box in house conditions.
Management of transmission is in detail described in the Head Governing bodies and methods of safe operation.
Procedures of removal and installation are similar to removal and the manual transmission installation, the description is provided in the Section Removal and installation of the check point.
Automatic transmission, in the course of start-off from the place, performs function of ordinary coupling, and during the movement performs work on gear shifting.
The AT main hubs are: torque converter, planetary reducer and hydraulic or electronic control system. Hydrodriving disk brakes and disk coupling are applied to transition to another transfer the relation in a planetary reducer.
The torque converter on the functions corresponds to hydraulic coupling. Its task includes implementation of coupling at start-off from the place and gear shifting.
Control of switching is exercised of the electronic block. At the same time the electronic block for the correct management uses various information which allows for each mode of the movement of the car and depending on desire of the driver to choose the most optimum transfer relation.
Switches of programs, such as "Economy" or "Sport", are not required since the control unit automatically, on the mode of the movement, establishes switching points. When determining points of switching also resistance to the movement, such as, rise or descent from the mountain, towage of the trailer and existence of a head wind are considered.
The control system can work in the special safe mode into which passes at detection of any malfunction. At the same time operating modes of transmission are limited, and the car can be delivered under the own steam to repair shop. Upon transition of a control system to the safe mode on the control panel the control lamp lights up (address the Head Governing bodies and methods of safe operation).
Analyzing information arriving from various sensors (not only the sensors directly related to transmission), the control system chooses optimum from the point of view of profitability, smoothness of the course, etc. a box operating mode. At a certain position of the gate of a throttle the control system can block the hydrotransformer in such a way that only the fourth and fifth transfers will join. It reaches considerable decrease in consumption of fuel.
The only regular procedure of service of a box is check of level of working liquid (address the Section Check of Level of Oil of Automatic Transmission). Regularly it is not necessary to change transmission liquid.
Near a radiator of the cooling system the cooler of transmission liquid is established.
There are several operating modes of transmission, each of which can be involved after moving of the selector to one of the following provisions: P, R, N, D, S (address the Head Governing bodies and methods of safe operation).
The engine can be started only if the selector is in the provision of P or N. It is made to prevent the movement of the car in start attempt (if the selector is installed in one of other provisions). Analyzing information arriving from sensors, the control system resolves or forbids start of the engine. The locations of various relays are specified in the Head Onboard electric equipment.
The selector of 5-staged AT Tiptronic near a path of provisions of automatic switching has the second path of step-by-step (consecutive) switching. The sports steering wheel can be equipped with the corresponding keys. Such switching is accepted in sports cars.
In the presence of Tiptronic box the driver can make compulsory switching to higher and lower transfers. In comparison with manual switching of Tiptronic more with comfort it is also protected against wrong management. So for example, switching to lower transfer is made only if turns at the same time do not overstep certain bounds.
With malfunctions of entrance signals or electromagnetic valves switching to the emergency program is made. At the same time arisen malfunction registers in memory of malfunctions. Information from memory can be a schitana the special device.
Automatic transmission of Multitronic with stepless gear shifting
Stepless AT Multitronic
Multitronic - stepless transmission of CTV with smoothly changeable transfer relation which provides not only effective use of engine capacity but also provides good dynamics and comfort of driving.
Basic element of the Multitronic system is klinotsepny the variator. By means of a variator the transfer relations between the start-off mode from the place and the last transfer change smoothly. Thanks to it the engine, irrespective of the mode of the movement, power or economic, works in the optimum mode corresponding to it. The variator consists of two conic couples connected with each other by a lamellar chain. As in each couple of disks the conic disk moves the electrohydraulic drive, the working diameter of a chain and thereof the transfer relation smoothly changes. Besides, in Multitronic the coupling cooled by oil which excludes not only typical shortcomings of the converter of torque is applied, but also gives the chance of various options of start-off from the place. The option is chosen an electronic control system according to desire of the driver which is distinguished on the nature of movement of the accelerator pedal. Besides, electronically controlled coupling realizes the stable mode of the creeping movement which is a comfort element. The electronic control system, besides, provides an identification of the driver and state of environment and works with the dynamic program of regulation of DRP. The specified program for the nature of movement of the accelerator pedal defines whether the driver wishes to move in dynamic or in economy mode.
If the driver gives full gas (kik-Down), the electronic control system at once switches to sports control mode and lowers transfer that provides the necessary high speed of the engine. At the normal mode of the movement the choice of the optimum transfer relation, and all its changes, unlike step switching of AT is made, are carried out smoothly, without breakthroughs and is imperceptible. Electronics distinguishes also rises and descents and compensates additional loading or increases the braking moment the engine.
In the mode of manual switching of 6 control units of the fixed transfer relations (transfers) brought in memory can smoothly be switched by the lever of the selector or buttons on a steering wheel.