jcb EcoMAX - SCR System; Schematic Illustration of the SCR System; Component Overview

JCB EcoMAX Engine Installation Manual
Page 48 of 64 320/A9164-1 © JCB Power Systems Ltd.
17.3 SCR System
17.3.1 Schematic Illustration of the SCR System
Figure 14: SCR system
17.3.2 Component Overview
DEF Solution
DEF (DIN70070) is an aqueous solution of 32.5% urea to 67.5% deionised water with a
freezing point of -11°C. If stored above 30°C for prolonged periods it starts to prematurely
degrade, increasing its corrosive properties.
Supply Module
The supply module pumps DEF from the DEF tank to the dosing module. For operation in
low ambient temperatures, it uses an integrated electric heater which is capable of defrosting
the supply module before operation and stopping it from freezing during operation.
Dosing Control Unit
For any given machine operating condition, the dosing control unit calculates the DEF
injection quantity. This regulates the dosing module actuation and the supply module
pressure (among other functions) to make sure the correct quantity of DEF is supplied. The
correct installation of the upstream temperature sensor combined with the up and
downstream NOx sensors are critical to the correct operation of the system. To protect the
NOx sensor elements, the sensor probes are heated systematically to bring them up to the