Hello!
I've been away from using VEMS for few years but now a new kind of need has arisen. I'd need a programmable unit to control Borg Warner VGT turbochargers. Yes, two of them.
Required inputs would be (at least):
RPM
MAP
TPS
Vane position feedback x2 -PWM-
Required outputs would be (at least):
Vane position control x2 -PWM- 250Hz
Also 3D map for those outputs is needed, in a function of RPM & MAP. With vane position feedback.
OEM style vane movement check at engine start would be nice.
A big plus would be a possibility to add 2x EGT inputs and use a limit/alert temperature for safety.
More to ask:
-Aux coolant pump switching in relation to RPM and timed/temperature controlled switching off after engine shutdown for turbocharger cooling.
-MAF signal massaging so that from two inputs one output is calculated, ie: x + x = y
These two last ones because there's individual boxes available but one that can do all this would be nice.
Am I asking too much??
TIA, Pete
Here's some data about OEM control unit's operation, from a certain OEM publication:
Position Sensor
A contactless incremental Hall sensor is used to detect
the position of the output shaft. The hybrid electronics
integrated in the adjuster housing is responsible for
position control and control of the DC motor. The sensor
magnet wheel is mounted on the DC motor shaft, while the
sensor (pick-up) itself is located on the hybrid electronics.
The main advantage of the contactless sensor is freedom
from wear.
In addition to digital position control and related
setpoint/actual value evaluation and driver control, the
electronic components also perform actual value output as
well as diagnostic and fault detection routines.
Each boost pressure adjuster is connected to the DME
control unit by two signal lines. The DME control unit
sends a setpoint (PWM signal) or special pulse/duty ratios
(e.g. command to travel to and learn end stops) via one of
the lines. The electric boost pressure adjuster then sends
the actual value (PWM signal) and special pulse/duty ratios
(self-diagnosis of electric adjuster for fault memory entry
in the DME) to the DME via the other line.
Diagnosis Of Electric Boost Pressure Adjuster
The electric boost pressure adjuster features an integrated
diagnostic function which transmits a fault to the
DME control unit by way of a corresponding pulse/duty
ratio.
• The nominal mechanical adjustment range or control
range ( R ) extends from 20 % (vanes open) to 80 %
(vanes closed).
• The pulse/duty ratio is approx. 40 % when the ignition is
switched on.
• The pulse/duty ratios 0 % to 19 % and 81 % to 100 %
are special pulse/ duty ratios for diagnostic routines ( D
) and for teaching the adjusting device.
Boost Pressure Adjuster Test
When the ignition is switched on, the function "Test boost
pressure adjuster" is available on the PIWIS Tester in the
DME control unit under the system test function. A corresponding
fault is entered after this test in the event of
malfunctions.
In order to check functioning of the adjusting device, the
electric boost pressure adjuster is supplied with a
pulse/duty ratio of 16 % and 84 % after the ignition is
switched off. The function test is also audible for the
customer.
Adaptation Of Boost Pressure Control
The boost pressure is a variable which is influenced by
engine tolerances and ambient conditions. The following
ambient conditions influence the boost pressure with
respect to the maximum engine torque, protection of the
engine and turbocharger as well as fault entries.
• Air pressure (the boost pressure is adapted from an
altitude of
> 5,900 ft (1,800 m) in order to protect the components
of the turbocharger).
• Ambient temperature and intake air temperature (charge
air temperature) (the boost pressure is reduced at an
ambient temperature
< approx. 32° F (0° C), or a charge air temperature <
approx. 50° F.
(10° C).
• Fuel quality (knock resistance under thermodynamic
loading).
The adaption ranges 0 to 11 are available for boost
pressure adaptation. These are divided into 3 load ranges
(boost pressure) and 4 engine speed ranges. Adaptation
of +/- 15 % is possible for each range before a fault is
entered.
Table Of Boost Pressure And Speed Thresholds
2250
2050-2-5-8-11
1800-1-4-7-10
1500-0-3-6-9
2500_3700_4900_5800_6500
Y= plsol – Boost pressure in mbar
X= nmot -- Engine speed in rpm
Partial Load Adaptation
The adaptation ranges 0 / 3 / 6 / and 9 are available for
partial load or reduced full load due to ambient conditions
(e.g. poor fuel quality).
Full Load Adaptation
The adaptation ranges 1 / 4 / 7 / and 10 are provided for
full load under normal conditions.
Full Load With Overboost
The adaptation ranges 2 and 5 are available for full load
with Overboost (Sport Chrono activated). The adaptation
ranges 8 and 11 are not normally adapted.
