Exhaust gas recirculation vacuum transducer design - GF07.17-P-3157-01H

The pressure transducer is inserted for actuation of vacuum control units. At the same time control pressure is generated according to the electrical input signal from the engine control unit and is transferred to the subsequent actuator.

A magnetic field is built into the coil (e) which varies the air gap (s) proportionally to the control current of the engine control unit.

The dimension for the size of the output signal is the control vacuum.

No signal from control unit 

In de-energized state the air gap (s) is at its largest.

A pressure compensation of the ATM can only occur via the perforated disk (g) and the holes in the housing (c), furthermore via the restrictor orifice (n), through the filter (f) to OUT.

Because also the valve (b) can be pressurized from below with atmospheric pressure through the middle positioned hole in the housing (c), it can close with the help of the force of the spring (o) and the suction pressure from VAC.

The vacuum control unit is ventilated.

Signal from control unit 

If the coil (e) is now supplied with control current, a magnetic field builds up in the anchor (l), whereby the perforated disk (g) is drawn against the seat of the brass disk (h). The hole is closed after ATM.

Now that the lower chamber (m) of the diaphragm (d) is no longer under the atmospheric pressure, the spring (a) can press down the diaphragm as well as the valve (b) and can free the channel from VAC. Then the vacuum reaches from VAC via the restrictor orifice (n), further through the filter (f) to the individual vacuum control unit.

A permanent changing control current in the coil can assure a constant vacuum supply.