US 4,086,804 A · Precision pneumatic pressure supply system

Abstract

A dual closed loop, precision pneumatic pressure selection, control and display system for use in testing pneumatic apparatus provides precision digital high response analog control of a precision pneumatic valve for establishing, maintaining, and displaying selected reference pressures and rates of change thereof as a ratio between a regulated pressure and a vacuum, the resultant pressure being sensed by a precision pressure sensor of the vibrating diaphragm type. The first closed loop is a digital loop, the desired reference pressure or pressure rate being commanded in any desired pneumatic unit of measure as a binary coded decimal signal and converted to a common unit of measure. The output of the pressure sensor responsive to valve operation is converted to a binary coded decimal signal in said common units, these two signals being digitally compared and the difference between them being converted to an analog signal for adjusting the valve, thereby maintaining the selected pressure. The second loop is a high response, high resolution analog control loop system wherein the analog error signal of the first loop controls valve position, a further output of the pressure sensor being converted to an analog signal and compared with the analog error signal to adjust the valve so as to zero the analog error signal. Thus, the system employs duel control loops combining the high precision of a digital process closed loop. The system uses similar and separately selectable P.sub.S and P.sub.T outputs in terms of inches of mercury, millibars, feet, knots, feet per minute, knots per minute, etc., with channels which may be cross-coupled one to the other to yield Q.sub.C control without requiring a separate sensor.

Claims16

Dependent claims

A controllable precision pneumatic pressure supply system for use in testing pneumatic apparatus comprising

pneumatic means for supplying a controllable pneumatic pressure to the apparatus under test and including pressure responsive means for supplying a measure of said pressure,
a precision digital closed loop control including means for providing a digital representation of a desired supply pressure, means for supplying a digital representation of the pressure supplied by said pressure responsive means, digital means for comparing said measures and providing a digital measure of the error therebetween, and means responsive to said digital error measure for providing an analog error signal proportional thereto,
a high response, high resolution analog closed loop control including means responsive to said analog error signal, means for supplying an analog signal representative of the pressure supplied by said pressure responsive means, and summing means responsive to said analog signals for controlling said pneumatic means in a manner to reduce any difference between said analog error signal and said pressure responsive means analog signal to zero,
whereby the pressure supplied to said apparatus under test corresponds to the digital representation of said desired pressure.

1 more element

A controllable precision pneumatic pressure supply system for use in testing pneumatic avionic apparatus of the type normally responsive to pitot static, pitot dynamic and/or total pitot pressures comprising

first and second substantially identical pressure supply channels for supplying controllable pitot static reference pressure and pitot dynamic reference pressure respectively to said apparatus under test, each channel comprising
pneumatic means for supplying said reference pressure to the apparatus under test and including pressure responsive means for supplying a measure of said pressure,
a precision digital closed loop control including means for providing a digital representation of the pressure supplied by said pressure responsive means, digital means for comparing said measures and providing a digital measure of the error therebetween, and means responsive to said digital error measure for providing an analog error signal proportional thereto,
a high response, high resolution analog closed loop control including means responsive to said analog error signal, means for supplying an analog signal representative of pressure measure supplied by said pressure responsive means, and summing means responsive to said analog signals for controlling said pneumatic means in a manner to reduce any difference between said analog signals to zero, whereby the pressure supplied to said apparatus under test corresponds to the digital representation of said desired pressure, and
means responsive to the digital representation of the desired supply pressure of said first channel for modifying the digital representation of the desired supply pressure of said second channel whereby the pressure supplied to said apparatus under test corresponds to total pitot pressure.

2 more elements

Dependencies are inferred from the claim text.

Precision pneumatic pressure supply system

Life of this patent

Precision pneumatic pressure supply system

Life of this patent

Abstract

Claims16