The intake manifold of the Y 25 DT engine is made of plastic.
It distributes the intake air to two different inlet ducts per cylinder. The intake air is conducted through the inlet swirl duct and, depending on the operating state of the engine, also via the open inlet swirl flaps through the inlet tangential duct to the combustion chamber.
The system comprises:
- Plastic intake manifold housing
- Swirl flaps in inlet tangential ducts
- Actuating linkage
- Vacuum unit
- Electric switchover valve
- Electronic control unit.
The swirl flaps (8) are located in the connection ports (6) upstream of the inlet tangential duct. One swirl flap is provided for each cylinder.
When the swirl flaps are closed, the intake air is conducted via the inlet swirl duct (5) to the combustion chamber. This provides the air with greater swirl and thus results in lower emission values in the lower engine speed range.
The vacuum unit (2) is actuated via an electric switchover valve (1) which is switched by the electronic control unit.
| 1 | Actuating valve | 6 | Connection port for inlet tangential duct |
|---|---|---|---|
| 2 | Diaphragm vacuum unit | 7 | Intake manifold housing |
| 3 | Transfer lever | 8 | Swirl flap |
| 4 | Swirl flap guide lever | 9 | Swirl flap control rod |
| 5 | Connection port for inlet swirl duct |
Illustration L0008374 shows the removed intake manifold from below.