Table of contents: General principle of operation ↓ Torque converter ↓
The automatic transmission of the Audi 100 is controlled electronically/hydraulically. In addition to four gears, this transmission also has two shift programs - "economical" and "sporty". Since July 1992, sensitive DSP control has been used in the 6-cylinder engines (see page 125).
General principle of operation
The core of the automatic transmission is the so-called planetary gear set. It consists of a gear around which three more gears rotate. A ring gear with internal engagement is put on top of all of this. Such units are assembled in pairs into one gear transmission and form their own small two-speed gearbox. The ingenious thing about such gearboxes is the way they are switched. The gear ratio is changed only by holding or releasing the elements of the planetary gear sets. Thus, switching occurs without interrupting the force. Holding and releasing is ensured by hydraulically controlled multi-plate clutches and multi-plate brakes.
To obtain a multi-stage gearbox, three planetary rows are connected one after the other. This creates a four-stage gearbox with a reverse gear. The gearbox is coordinated by hydraulic control.
The section of the torque converter clearly shows the impeller and idler blades. The arrow points to the friction lining of the clutch for connecting the impeller to the engine, which - except for cold ATF conditions - switches to a rigid through drive from higher gears to prevent slippage.
Torque converter
The engine thrust is transmitted to the gearbox via a fluid. The engine sets the pump wheel in motion in the torque converter. The fluid of the transformer, set in motion, can now in turn set the turbine wheel in motion. There is always a difference in the number of revolutions between the pump wheel rotating at the engine shaft speed and the turbine wheel at the input of the gearbox. When starting off, this difference is greatest; as the speed increases, the speeds of the pump and turbine wheels become increasingly equal. In our gearbox, the torque converter is blocked in the third and fourth ranges of gear ratio change, i.e. a rigid connection is created between the engine and the automatic transmission. This saves fuel.
This article was previously published on the resource: AudiManual.ru