SCR compressed air pressure sensor, component description

B14.40-0016-08

1 Metering unit

Arrangement

The compressed air pressure sensor (4) is fastened to the outside of the metering unit (1). The metering unit (1) is located close to the last cylinder head cylinder.

4 SCR (17B06) compressed air pressure sensor

Task

The compressed air pressure sensor (4) captures the AdBlue pressure at a measuring point inside the metering unit (1) and transmits the information to the engine control module (MR), as an electrical tension signal.

B14.40-0026-11

Composition

The compressed air pressure sensor (4) consists of a threaded stainless steel housing and an electrical connector.

The inside of the compressed air pressure sensor contains, as a measuring element, a silicon membrane fitted with measuring strips. These measuring strips are electrical resistors that, during their expansion, modify their resistance (piezoresistive principle). The compressed air pressure sensor (4) is fitted with a drilling, through which the compressed air can penetrate up to the membrane. The compressed air pressure sensor (4) is an active sensor. i.e., it is supplied with a tension.

Function

The air actuating on the compressed air pressure sensor (4), presses the internal membrane. This pressure that causes the membrane, when expanding, to modify its electrical resistance on the measuring strips. With these pressure alterations, occurs the increase or decrease of the measuring strips resistance

The variations of electrical resistance are transmitted in defined intervals as analog signals to the control module (MR).

The control module (MR) calculates the corresponding pressure, starting from the resistance values.