An Expert System for Engine Diagnosis and

Maintenance

DICARE

®

m

DICARE is an expert system, which provides current diag-
noses for four-stroke diesel engines. The diagnoses
system DICARE describes and diagnoses the present
engine condition and gives advice regarding condition-
based maintenance. In combination with planned mainte-
nance measures this creates the prerequisites to guarantee
many years of trouble free engine operation. DICARE is
working as on-line system, however, data logging (off-line
system) is also possible. Apart from using the system on
site, the technical management can always call off informa-
tion about the condition of the engine by means of data trans-
fer via modem or by exchanging diskettes and schedule
maintenance work accordingly. This will result in an optimised
utilization of personnel an spare parts.

Working principle and basis for diagnosis

DICARE helps to detect deviations of one or several current
engine operation values from the set values of a perfect
running engine, to diagnose and indicate the causes and to
provide advice to remedy faults. The basis for the diagnosis
are the measured data, which were recorded during the
acceptance trials on the test bed in order to obtain the
complete performance characteristics of the engine. These
basic data are compared to the current engine data after
conversion into standardized ambient conditions and a
correction in order to take into account the current differ-
ence in net calorific value with regard to the test bed condi-
tions. On the basis of a reliable recording of measured
values and due empirical data as well as plausibility consid-
erations the system points out causes and malfunctions.
The Windows surface allows simple handling by means of
the windows technique with pull down menus acc. to the
international standard. When the mouse pointer is moved
over an operating element, such as a button or an input
field, explanations regarding the respective function are
displayed automatically.

Quick overview of the
current operating conditions of the engine plant

The interface to the measuring data of the engine is still
being realized via the alarm system. In future the DICARE
data will be supplied directly from the engine via a BUS-
system.
After selecting the ”Prediagnosis” all the installed engines
can now be called simultaneously on the screen ( see fig. 1
for 4 engines).
These engines are subdivided into the following 5 measure-
ment groups:
·

Exhaust gas temperature

·

Turbocharging

·

Fuel

·

Lubricating oil

·

Cooling water

If measured values deviate from the set value, this is indi-
cated by a change in colour of the related measuring group.

DICARE

®

An expert system for engine diagnosis

Fig. 2: Engine with measured values

Fig. 1: Prediagnosis

This prediagnosis, which is especially suited for on-line
operation, shows at a single glance and with reference to
output, which engine and which area of this engine
requires particular attention.
Additional information can be called by double clicking. The
selected engine will the be displayed with all its measured
values. The measured values, which are below or above a
set value, will be displayed as red (too high) or blue (too
low) flashing figures (fig. 2).

Automatic diagnosis and
recommendations for maintenance work

A verbal interpretation of the existing deviations can be
obtained by selecting the menu item for individual diagno-
sis. This diagnosis is easily accessible and can be read in
groups as on index cards. It uses the 5 measured value
groups already displayed in the prediagnosis, plus the
additional groups General, Firing pressures and Recom-
mendations. Important information is marked by
symbols on the index cards. The three symbols “Info” ,
“Warning” and “Critical” are used (fig. 3).

Database management and graphic display

The basic data and current measuring data are maintained
in databases.
Measured data such as rotational speed, temperatures and
pressures are graphically displayed in analogue form on
symbolized measuring instruments. Therefore every
measured value can be accessed both in its position with
regard to the set value and absolutely (fig. 4).

Fig. 3: Individual diagnosis

Basis for long-term protocols

Due to the automatic recording of the measured values in
DICARE the data are archived automatically. All values
recorded by instruments are stored in a database. This
memory can be accessed via a menu item at any moment.
In the display of all measuring points as daily protocol over
different, predefined periods between 6 hours and one week
it forms a kind of “black box” retrospectively for 14 days.
This permits to duplicate the operation of the engine.

Fig. 5 shows for example the differential pressure of the
charge air cooler and turbine speed within a period of 6
hours.

Fig. 4: Symbolized measuring instruments

Timely planning of maintenance measures
by means of trend analysis
Slow changes can be particularly well recognized in a long-
term analysis. However, for reasons of capacity it is not pos-
sible to store all the data for several years. Therefore a

representative set of measured values is formed from the
288 sets of measured values of one day. This set is the shown
in the display of the deviations from the set value. Different
periods ranging from one month to five years can be
chosen. Fig. 6 shows the long-term behaviour of the
exhaust gas temperature after turbine as deviation from the
set value with superimposed trend line. The period of the
trend can be superimposed by another function.

Fig. 5: Daily Record

Manual input of measured values

In case of sensor failure the measured values can be
entered manually or changed. This is possible via the menu
item “Loading of measured values”. Here as well an index
card box arranged in groups is displayed on the screen,
permitting to change any value or enter it new. These
values are then stored, recognizable as manual measuring
series. There is enough space for comments or notes, in
which for example the reason of the manual input may be
indicated.

Communication with other programs

From the menu “Info” it is possible to pass over to another
program. This permits an easy access to all information from
acceptance test record via engine operating instructions,
spare part catalogue as well as planned material mainte-
nance and spare parts management.

Fig. 6: Long-term protocol

THESE ARE THE ADVANTAGES OF DICARE:

DICARE permits a quick overview of the
current operating conditions of the
engine plant.

Due to the automatic elaboration of a
diagnosis DICARE provides recommen-
dations for maintenance work.

DICARE automatically records operating
values and draws up long-term protocols
from these.

DICARE provides trend analysis, which
permit spare part and personnel dispo-
sitions.

DICARE generates a gapless documen-
tation with graphic evaluation of the op-
erating values. This avoids mistakes,
which might occur when making entries
in daily logs.

DICARE permits to call off data of the
running engine from a basic station by
means of data telecommunication. Thus,
the engine can be checked from far away.

DICARE permits the utilization of the
remote diagnosis, a service rendered by
the Caterpillar Central Services. This
provides additional advantages in terms
of a precise assessment.

DICARE therefore creates the prerequi-
sites for: optimum operating condition
and high availability of the plant, permits
a condition-based maintenance and
helps to cut operating costs.

Engine control room >>Langeland<<