Electronic Control Unit

ECU

The HJS ECU is a control unit that has been specially developed for the requirements of exhaust gas aftertreatment for diesel engines. The software controls and monitors ^CRT®, ^SMF®-AR, FBC and ^SCR/SCRT®systems. Both a CAN-BUS interface (KWP2000, SAE-J1939) and a separate RS232-based diagnostic interface are available for diagnostics. The latter enables convenient evaluation of the system via specially developed software.

The HJS ECU offers the following main functional features:

Filter condition monitoring

In the ^SMF®-AR, ^CRT®and ^SCRT® systems, the loading status of the diesel particulate filter is continuously monitored using various sensors.
The system is also permanently monitored for malfunctions. If necessary, the driver is notified via a display or indicator lamps.

Control of thermoelectric regeneration

With the ^SMF®-AR system, soot burn-off is initiated by means of radiant heating to regenerate the filter.
Power control of the control unit (2x 50A/ up to 2kW) ensures optimum temperature of the radiant heating.
Various models run in the control unit to calculate the optimum switch-on time for the radiant heating, which can be weighted differently depending on the application profile.

Additive dosing

An iron-based additive is metered into the fuel in the FBC and ^SMF®-AR systems to reduce the soot ignition temperature and accelerate soot burn-off.
The additive is measured as standard by determining the amount of fuel added via a tank sensor signal.
Systems without a fuel tank sensor can optionally be switched to intelligent, continuous dosing. In this case, the dosing quantity is calculated based on the average fuel consumption.

^AdBlue® injection

In the SCR and ^SCRT® systems, an AdBlue air-assisted dosing system is used to reduce nitrogen oxides (NOx).
The AdBlue dosing system is controlled via the HJS ECU.
Malfunctions are processed via the HJS ECU and, if necessary, indicated to the operator via a display or indicator lamps.

General

Relevant environmental data and any errors that occur are stored in the internal data memory for at least 30 days (fulfillment of VERT requirements).
The diagnostic functions of the HJS ECU meet the requirements of on-board diagnostics (OBD I).
The HJS exhaust gas aftertreatment system can operate autonomously, i.e. exclusively with its own sensors. If desired, existing sensors on the vehicle can also be read in and used.
As an option, communication can also be established with the motor control unit in order to request a derate signal if required, e.g. in the event of a filter overload.

Technical data

Dimensions: 185 x 149 x 40mm
Weight: approx. 650g
Protection class: IP6K5
Supply voltage: 10 – 30V, reverse polarity protected
Power consumption: in operation < 130mA, in standby < 0.5mA
Operating temperature range: -40 °C to +85 °C
Service life: > 20,000 operating hours
Storage of measurement data: > 10 years (de-energized)
Interfaces: 2x CAN (high-speed, configurable 125kBaud – 500kBaud), RS232 (TTL)

HJS ECU diagnostics software

The ECU diagnostic software is required for the installation, maintenance and troubleshooting of an HJS diesel particulate filter system with electronic monitoring (e.g. ^SMF® with passive regeneration technology or ^SMF®-AR).

A standard laptop and a diagnostic cable are used to communicate with the HJS ECU of the filter system via the diagnostic software. Data can be read out and actions executed. In order to be able to use all the necessary functions of the ECU diagnostics software, registration is required before first use. Registration is carried out using a password, which customers can obtain from a sales partner.