Exhaust Gas Recirculation Vacuum Transducer, Function

Exhaust Gas Recirculation Vacuum Transducer, Function




a Compression spring
b Valve plate with diaphragm
c Housing, pressure regulator
d Hose line (guides controlled vacuum of approx. -200 mbar to the electrical unit)
e Coil
f Electromagnetically operated valve unit
ATM Atmospheric pressure, air admission via cylinder head
OUT Controlled vacuum to EGR valve
VAC Vacuum supply from intake manifold

From connection VAC the intake manifold vacuum reaches the pressure regulator, which stabilizes the intake manifold vacuum in line with engine speed and throttle valve position via a control valve to approx. -200 mbar.
The controlled vacuum flows further via a hose line to the following electric unit.
This unit is actuated by the ME control unit with a pulse width modulation signal (frequency approx. 10 Hz, on/off ratio approx. 30 to 100%) at the ground end. The developing magnetic field influences via the coil anchor the valve unit as follows:

- No signal from control unit:
The connections OUT and ATM are linked. The exhaust gas recirculation valve is close (ventilated).
- Signal from control unit:
The valve unit opens proportional to the current flow in the coil. The vacuum acts partially or fully at connection OUT and operates the ERF valve accordingly.