Solenoid Valve control system

[ COMPUTER OPERATED SOLENOID VALVE PRESSURE CONTROL SYSTEM [75] Inventors: Frederick Gordon Sholes, Jr.; Gary Eugene Lovell, both of Littleton,

[73] Assignec: Martin Marietta Corporation, New

York, NY.

[22] Filed: Dec. 17, 1973 21 Appl. No.: 425, 663

[52] U.S. Cl 235/l5l.34; 73/205 R; 137/6241] [51] Int. Cl G06f 15/20; GOlp 5/14 [58] Field of Search 235/1512, 151.3, 151.34, 235/l5l.1; 73/197, 205, 211; l37/624.11,

[56] References Cited UNITED STATES PATENTS 3, 555, 901 1/1971 Delatorre et al 73/205 X ATMOSPHERE VACUUM SOURCE 1 Apr. 15, 1975 3, 741, 246 6/1973 Braytenbah 137/624, ]1 3, 752, 393 8/1973 Moseley 73/211 X 3, 794, 070 2/1974 Klem et al. 137/624.l l X Primary Examiner loseph F. Ruggiero Attorney, Agent, or Firm-Sughrue, Rothwell, Mion, Zinn & Macpeak [57] ABSTRACT A computer operated solenoid valve pressure control system is disclosed. The apparatus of the system in cludes a computer, equipment which converts the computer instructions to electrical power to operate solenoid valves which with associated components pressurize or depressurize a closed volume, and a pressure measuring system which provides feedback to the computer. In applications where the pressurized device varies in volume or there is flow through the pressurized device, the pressure from the closed volume is fed to a pilot regulator system.

16 Claims, 2 Drawing Figures PATENTEDAPRI 51925 3, 878 376 5 (6 A%%LREEJ&D ANALOG To DIGITAL REGISTER SOLENmD CONVERTER COMPUTER 3\ DRWER 4 COUNTER V MULTIPLEXER L r 7 TIME' REFERENCE CLOCK p x v PRESSURE TRANSDUCER |2 3 HIGH suPPLY PRESSURIZED ATMOSPHERE VOLUME I6 :5 w (CL03ED) VACUUM souaca= 9 24 VACUUM |9 SOURCE SUPPLY HIGH 22 PRESSURE COMPUTER OPERATED SOLENOID VALVE PRESSURE CONTROL SYSTEM BACKGROUND OF THE INVENTION This invention relates to systems for controlling pressures, and more particularly to a computer controlled solenoid valve pressure system.

Fluid pressure control systems are utilized in, for example, automatic control of test equipment and in automated industrial applications where fluid pressure is used as stimulusor as a control signal for other devices such as pressure, flow. and temperature regulators. The prior art pressure control systems often utilized for au tomated control of test equipment or for automated industrial applications are systems employing electronically operated motors to set regulators or systems that employ an electronic device to send reference current to a device such as a servo valve. These prior art systems are often slow, complex, costly and have a low reliability.

This invention provides a pressure control system that is computer controlled. The system is relatively fast acting and has a high degree of reliability. Further, the system of this invention is not a complex system; and when incorporated with apparatus that has an existing computer, the system is very low cost in comparison to many of the prior systems. While this invention may be used in many automated test systems or automated industrial processes, it is ideally suited for use with the automatic jet engine accessory test system disclosed in a co-pending U.S. Pat. application Ser. No. 425, 649, filed on Dec. 17, 1973, by Gary E. Lovell and William .1. Wise and assigned to the assignee of this invention.

SUMMARY OF THE INVENTION The computer controlled solenoid valve pressure system of this invention includes means to translate instructions from a computer to electrical signals to operate solenold valves. The valves, in conjunction with other apparatus of the system, pressurize or depressurize a closed volume. A pressure measuring system provides feedback to the computer.

The desired pressure is fed to the computer by the program. The computer is programmed to measure existing pressure, select a valve, and compute the time this valve must be open to obtain the desired pressure. A digital counter converts a time valve signal in digital form from the computer to a signal of specified time duration by counting impulses from a time reference clock. A solenoid address register connects this signal of specified time duration to the selected solenoid valve driver to open the selected valve for a specified time.

BRIEF DESCRIPTION OF THE DRAWING The exact nature and specific details of the invention will be apparent from the following detailed description of the invention when read in conjunction with the annexed drawing in which:

FIG. 1 shows a preferred embodiment of the invention with a pilot regulator system necessary only for special specific applications; and

FIG. 2 shows a flow controller that can be used with the system of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION Referring to FIG. 1, a computer 1 is connected to a solenoid address register 2 and to a digital counter 3. A time reference clock 4 is connected to counter 3. A solenoid driver 5 is connected to the output of solenoid address register 2 and to the output of counter 3. The output of solenoid driver 5 is connected to the solenoid valves I0, l2, l4 and 17. Valve 10 has an associated orifice II. Valve 12 has an associated orifice I3. Valve 17 has an associated orifice l8 and valve 14 has an associated pressure regulating valve 15 and orifice 16. All the valves and associated orifices are fluid coupled to a pressurized closed volume 9 as shown in FIG. 1. Valves l0 and 12 are fluid coupled to a high pressure supply and valves 14 and 17 are fluid coupled to the atmosphere and a vacuum source, respectively.

Closed volume 9 is connected to a pressure transducer 8 which in turn is connected to a multiplexer 7. The output of multiplexer 7 is connected to an analog to digital converter 6 and the output of analog to digital converter 6 is connected to computer 1.

The desired pressure in pressurized closed volume 9 is an input to computer 1 in a program. Computer 1 is programmed to measure the existing pressure in pressurized closed volume 9 and compare this pressure to the desired pressure. In response to this comparison, computer 1 selects which of the valves l0, l2, l4 and 17 must be opened to obtain the desired pressure and computes the length of time this valve must be open to attain this desired pressure. After computing the time the appropriate valve must be open, computer 1 applies a digital time measure signal to digital counter 3. Counter 3 converts this digital time measure signal from computer 1 to a specified time duration signal by counting impulses from time reference clock 4. This signal of specified time duration is applied to solenoid driver 5. During the same time, computer 1 provides a valve select signal to solenoid address register 2. Solenoid address register 2, in response to this select signal from computer 1, transmits a signal to solenoid driver 5 to energize the proper solenoid by the signal from counter 3. Thus, address register 2 in combination with counter 3 energizes the proper solenoid for the specified time so that the proper valve will be open for the proper amount of time to attain the desired pressure in pressurized closed volume 9.

If computer 1 indicates that the pressure in closed volume 9 is to be increased, either valve 10 or valve 12 will be opened for the specified time. The valve 10 and 12 and their associated orifices 11 and 13 provide two ranges of fluid flow to closed volume 9. Computer 1 selects which of the two valves 10 and 12 will be opened and thus selects which of the fluid flow ranges is selected for a given condition.