Turn use automatic
The concept of the automatic swing utilization (SNA) came about at Volkswagen at the end of the 1970s against the backdrop of the second oil crisis .
The SNA consists of an automatic clutch and a start-stop system . This combination makes it possible to open the clutch, automatically switch off the engine and restart it when accelerating. This happened not only when stopping at traffic lights, but also while driving. So the system took advantage of the momentum.
There were two versions:
- SNA-1: The engine is started by the normal starter
- SNA-2: The engine is started by a flywheel, which is arranged between the clutch and the engine and is separated from the engine by a second clutch. An additional small electric motor is available to drive the flywheel for the first time and to get it going again after longer stopping phases.
history
In 1980, Volkswagen wanted to use the SNA-1 concept in the USA in the Golf. However, the end of the oil crisis also meant the end of this project.
In 1994 the SNA-1 was used in the Golf III Ecomatic . The automatic clutch actuation was carried out by an electro-pneumatic servomotor, and a variant of the Digimat was used as the control unit .
In 1999, the concept was used in the Lupo 3L TDI , in which, in addition to the clutch, the transmission was also hydraulically actuated; a variant of the Digimat took over control, now with CAN networking. In order to obtain servo support for the brakes, only the clutch was disconnected during the journey in the "sailing phases", but the engine was not switched off.
Today the concept is being revived in starter-generator systems for low-energy vehicles .