Pneumatic generator system for simulating operating conditions of an aircraft

• US 20040238039A1
• Filed: 05/29/2003
• Published: 12/02/2004
• Est. Priority Date: 05/29/2003
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Friedrichs, Hans Peter, Hubbard, Rondo K.
• Granted Patent: US 6,955,184 B2
• Time in Patent Office: Days
• US Class Current: 137/487.5
• CPC Class Codes: B64F 5/60 Testing or inspecting aircraft components or systems
• CPC Class Codes: G01M 3/26 by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors
• CPC Class Codes: G05D 16/2013 using throttling means as controlling means
• CPC Class Codes: Y10T 137/7761 Electrically actuated valve
• CPC Class Codes: Y10T 137/87917 Flow path with serial valves and/or closures

Abstract

A pneumatic function generator system for maintaining a desired pressure and/or a desired rate of pressure change with respect to time. The pneumatic function generator system may include a servo valve for controlling the amount of fluid traveling therethrough, a primary sensor for measuring the pressure of the fluid and for generating an analog signal corresponding to the pressure of the fluid, an analog-to-digital module for converting the analog signal to a digital value, and a digital device for receiving the digital value and, depending on the digital value, generating a control signal that is used to control the opening and closing of the servo valve.

Claims

1. A pneumatic function generator system for maintaining a desired pressure or a desired rate of pressure change with respect to time, comprising:

a servo valve for controlling the amount of fluid traveling therethrough;

a primary sensor for measuring the pressure of the fluid and for generating an analog signal corresponding to the pressure of the fluid;

an analog-to-digital module for converting the analog signal to a digital value;

an input port, coupled to the analog-to-digital module, for receiving an external analog rate or pressure command signal; and

a digital device for receiving the digital value and, depending on the digital value, generating a control signal that is used to control the opening and closing of the servo valve.

2. The system as defined in claim 1, further comprising:

a digital-to-analog converter for converting the control signal to an analog control voltage; and

a power amplifier for amplifying the analog control voltage and for offsetting the analog control voltage to produce a bipolar signal that is used to control the opening and closing of the servo valve.

3. The system as defined in claim 2, wherein the servo valve is a bipolar device having a plurality of electrically controlled apertures that open and close depending on the bipolar signal.

4. The system as defined in claim 1, further comprising an isolation valve having a first port coupled to the servo valve, a second port coupled to the primary sensor and an aperture between the first port and the second port, wherein the isolation valve is capable of isolating the servo valve from the primary sensor.

5. The system as defined in claim 4, further comprising a solenoid, coupled to the isolation valve, for controlling the opening and closing of the aperture of the isolation valve.

6. The system as defined in claim 1, further comprising an auxiliary sensor coupled to the first port of the isolation valve, for measuring the pressure of the fluid and for generating a pressure signal corresponding to the pressure of the fluid.

7. The system as defined in claim 1, further comprising:

a housing defining a chamber;

a temperature sensor disposed in the chamber, for measuring the temperature of the primary sensor; and

a heating device disposed in the chamber, for adjusting the temperature of the primary sensor.

8. The system as defined in claim 7, wherein:

the primary sensor is disposed in the chamber of the housing; and

the temperature sensor and the heating device are coupled to the analog-to-digital module.

9. The system as defined in claim 7, further comprising a digital input/output module coupled to the digital device and the heating device, wherein the digital device is configured to receive a measured temperature value from the temperature sensor, and based on the measured temperature value, command the digital input/output module to provide or terminate power to the heating device.

10. The system as defined in claim 1, wherein the analog-to-digital module includes:

a multiplexer for receiving the analog signal; and

an analog-to-digital converter for converting the analog signal to the digital value.

11. The system as defined in claim 1, further comprising a conditioning module having a circuit coupled to the analog-to-digital module and configured to receive a desired pressure signal.

12. The system as defined in claim 11, wherein the circuit includes a diode for limiting the voltage of the desired pressure signal and a capacitor for attenuating the noise in the desired pressure signal.

13. A method for controlling a servo valve to achieve a desired rate of pressure change, comprising:

receiving a desired rate value;

translating the desired rate value to a rate command;

determining a pressure value for a plurality of time values;

performing a least-squares curve fit using the pressure and time values;

determining an actual rate by calculating the slope of the least-squares curve fit; and

adjusting the servo valve based on the difference between the rate command and the actual rate.

14. The method as defined in claim 13, wherein the performing the least-squares curve fit includes computing a plurality of sums.

15. The method as defined in claim 13, wherein the performing the least-squares curve fit includes computing a plurality of first sums, wherein each of the plurality of first sums includes a term for each pressure and time value.

16. The method as defined in claim 15, further comprising computing a plurality of second sums, wherein each of the plurality of second sums includes a term for each pressure and time value.

17. A method for controlling the temperature of a sensor, comprising:

receiving a desired temperature value;

determining a nominal duty cycle for a sensor;

measuring the temperature using a temperature sensor;

comparing the desired temperature to the measured temperature;

if the desired temperature is greater than the measured temperature, then increase the nominal duty cycle; and

if the desired temperature is less than the measured temperature, then decrease the nominal duty cycle.

18. The method as defined in claim 17, wherein the nominal duty cycle is increased and decreased by an amount that is proportional to the difference between the desired temperature and the measured temperature.

19. The method as defined in claim 17, wherein the determining the nominal duty cycle for the sensor includes:

determining a rise time by measuring the time required for the temperature to rise above the desired temperature value when the duty cycle is maintained at about one-hundered percent;

determining a fall time by measuring the time required for the temperature to fall below the desired temperature value when the duty cycle is maintained at about zero percent; and

calculating the nominal duty cycle using the rise time and the fall time.

20. The method as defined in claim 17, wherein the determining the nominal duty cycle for the sensor includes:

determining an undershoot time by measuring the time required for the temperature to rise after the duty cycle has been changed to one-hundred percent;

determining an overshoot time by measuring the time required for the temperature to fall after the duty cycle has been changed to zero percent; and

calculating an adjusted duty cycle using the formula;

nominal duty cycle+one hundred-percent*(desired temperature−

measured temperature)/(undershoot+overshoot).