Shown above are four of the modules prepared for the CFM56-7 test box.
From left to right are driver modules for the HSPOV solenoid, BSV solenoid, VBV and TBV torque motors.
A complete test box for the CFM56-7 HMU will require 3 more torque motor drivers for VSV, LPTCC and HPTCC, plus the FMV resolver and closed loop module.
The modular format will allow these functional units to be used to test other fuel controlling systems as well.
For example, the functions of a Honeywell EK-209 APU test box could be duplicated using the FMV resolver and closed loop module, a torque motor module, and the HSPOV solenoid driver module from the CFM56-7 test box shown above and a COTS RTD temperature indicator.
The HSPOV module shown below provides a 0 to 32 volt switched output to operate the solenoid at up to 1A of current output. A pulsed output is provided for latching type solenoids. Circuits are provided to indicate the status of OSG and pressurizing valve switches with Red/Green LEDs on the front panel.
Left side view shows the cutout and heat sink for the output voltage regulator power transistor. This external mounting of the heat sink provides adequate cooling for the output transistor without need of a fan.
Right side view shows the mounting screws that hold the circuit board down, and the label for the Chassis Grounding screw.
The circuitry in the HSPOV module is shown above.
Torroidal transformers are used to reduce weight, noise and electro-magnetic emissions.
Ribbon cable is used to make all interconnections between the two circuit boards and the Datel panel meter.
The top-left DB-25 pin connector is the I/O to the HMU, carrying the current to the HSPOV solenoid coils and signals back from the pressurizing valve and OSG switches.
The DB-15 pin connector located on the left side is the I/O connector to the computer for remote control and data acquisition.
The DB-25 pin connector located at the top of the circuit board is a calibration test I/O connector, accessible through a port cut in the top cover, shown below.
port can be cut to allow just the connector to be plugged in, or extended to
allow access to the row of trimpots along the top edge of the circuit board
that are used to adjust and calibrate the circuits to make these adjustments
easier to access in the final configuration.
Shown above is a sketch of the proposed complete ATE-128 test box for the CFM56-7. The torque motor and solenoid drivers across the bottom row and the TBV/RACC in the upper right corner are completed. There are 3 extra slots in this rack for the resolver module.
Because the test box module enclosures are all custom-made by a local sheet-metal shop, we can design each module in any size and shape so the modules donít need to fit into anyone elseís pre-defined standard enclosures.
Form follows function, not the typical form follows available COTS enclosure dimensions.