Abstract:
A severe storm warning system includes an atmospheric pressure sensor utilizing an air-filled chamber with a first pressure sensor mounted between the interior of the chamber and the atmosphere and being located within the chamber interior and a second pressure sensor mounted between the interior of the chamber and the atmosphere and being located outside the chamber. Both sensors are formed of multiple-plate, floating plate capacitors which are movable in response to pressure changes. Electronic circuitry periodically determines what pressure changes have occurred and compares the changes to the changes associated with a predetermined signature of the type of severe storm being determined. Indicators including alarms are provided if a known sequence of pressure changes is detected.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     Not Applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable. 
     REFERENCE TO A MICROFICHE APPENDIX 
     Not Applicable. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to atmospheric pressure sensors and storm warning indicators and particularly to personal storm warning systems. 
     2. Description of Related Art 
     U.S. Pat. No. 5,612,667 discloses a device that uses a motor vehicle, and related devices, to gradually track barometric pressure for the purpose of alarming at the approach of severe weather conditions over an extend historical time period. 
     The prior art also includes other devices, of both mechanical and electrical design, that are presented as severe storm warning devices. These units are complex and expensive and do not satisfy the individual need for a device that monitors atmospheric pressure stability, and then responds to adverse atmospheric pressure conditions in a timely manner. What is desired is a personal severe storm warning system. The device should be inexpensive, simple in construction, self-compensating, of rugged design, user friendly and is free standing with reasonable battery life. None of the prior art devices are satisfactory. 
     BRIEF SUMMARY OF THE INVENTION 
     In one aspect of the present invention there is provided a severe storm warning system that comprises an atmospheric pressure sensing means for sensing changes in atmospheric pressure, the sensing means includes a chamber having an air-filled interior space and a first pressure sensor mounted between the interior space and the atmosphere for comparing the pressure inside the chamber with the pressure of the atmosphere and providing an output signal indicative of the results of the comparison. The first pressure sensor includes a multiple-plate floating plate capacitor having spaced plates movable in response to changes in atmospheric pressure with respect to the pressure inside the chamber. The first pressure sensor is located inside the chamber. 
     In other aspects of the invention there is a second pressure sensor mounted between the interior space and the atmosphere for comparing the pressure inside the chamber with the pressure of the atmosphere and providing a second output signal indicative of the results of the comparison, the second pressure sensor being located outside the chamber. The second pressure sensor includes a multiple plate floating plate capacitor having spaced plates movable in response to changes in the atmospheric pressure with respect to the pressure inside the chamber. The sensing means includes memory means for remembering the output signal and also includes circuit means for periodically detecting the output signal for determining changes in atmospheric pressure during a time interval as determined by the circuit means. The circuit means includes memory means for remembering the output signals periodically detected by the circuit means. The sensing means includes indicator means for providing indication when the output signals remembered by the memory means are of predetermined values as established by the sensing means. The predetermined values established by the sensing means includes a plurality of sequences of changes in atmospheric pressure of a predetermined typical signature for the type of severe storm being determined. 
     In other aspects of the present invention there is provided in a severe storm warning system comprising atmospheric pressure sensing means for sensing changes in atmospheric pressure, the sensing means includes detector means for sequentially determining the atmospheric pressure at selected time intervals and providing an output signal indicative of the difference in atmospheric pressure detected during one time interval and the atmospheric pressure detected at an earlier time interval, indicating means responsive to the output signal for providing an indication when changes of a predetermined nature in atmospheric pressure have occurred as determined by the indicating means. The detector means includes at least one multi-plate floating plate capacitor having spaced plates movable in response to changes in atmospheric pressure for varying the capacitance of at least one capacitor. The detector means includes memory means for remembering the output signals. The sensing means includes a chamber having air filled interior space, the detector means determining the pressure in the chamber and outside the chamber. There is also a first pressure sensor located inside the chamber. Also included is a second pressure sensor mounted between the interior space and the atmosphere for comparing the pressure inside the chamber with the pressure of the atmosphere and providing a second output signal indicative of the results of the comparison, the second pressure sensor being located outside the chamber. The second pressure sensor mounted between the interior space and the atmosphere for comparing the pressure inside the chamber with the pressure of the atmosphere and providing a second output signal indicative of the results of the comparison, the second pressure sensor being located outside the chamber. The second pressure sensor includes a multiple-plate floating plate capacitor having spaced plates movable in response to changes in the atmospheric pressure with respect to the pressure inside the chamber. The sensing means includes circuit means for periodically detecting the output signal for determining changes in atmospheric pressure during a time interval as determined by the circuit means. The sensing means also includes indicator means for providing an indication when the output signals remembered by the memory means are of predetermined values as established by the sensing means. The predetermined values established by the sensing means includes a plurality of sequences of changes in atmospheric pressure of a predetermined typical signature for the type of severe storm being determined. 
     In other aspects of the invention there is provided in a severe storm warning system comprising an atmospheric pressure sensing means for sensing changes in atmospheric pressure, the sensing means includes a chamber having an air-filled interior space and a first and second pressure sensor each mounted between the interior space and the atmosphere for comparing the pressure inside the chamber with the pressure of the atmosphere and providing a respective first and second output signals indicative of the results of each comparison. Each said first and second pressure sensor includes a multiple-plate floating plate capacitor, the plates being movable in response to changes in atmospheric pressure with respect to the pressure inside the chamber. The first pressure sensor is located inside the chamber and the second pressure sensor is located outside the chamber. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
     The novel features which are believed to be characteristic of this invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and method of operation, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings, in which: 
     FIG. 1 is an operating diagram of the severe storm warning system in accord with the present invention; 
     FIGS. 2 and 3 are operating diagrams of the-sensors of FIG. 1; 
     FIG. 4 is a cut-away pictorial illustration of the pressure sensing assembly in accord with the present invention; 
     FIG. 5 is a partially exploded view of a sensor of FIG. 4; 
     FIG. 6 is a partial top view of the assembly of FIG. 4; 
     FIG. 7 is a top view of a pressure sensor ring of FIG. 4; 
     FIG. 8 is a top view of a pressure sensor spring of FIG. 5; 
     FIG. 9 is a diagram of the circuit board used in the signal processing circuitry of FIG. 1; and 
     FIG. 10 is a partial schematic diagram of the processing circuitry used with the circuit board of FIG.  9 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Introduction 
     This invention is a device that detects and calculates the differential pressure between the real time atmospheric pressure and the historical atmospheric pressure contained in a reference chamber. The device uses two variable, floating plate capacitors, that are acted upon by flexible diaphragms, to measure variations in atmospheric pressure. One of the variable, floating plate capacitors is active when the real time atmospheric pressure is greater than the historical reference chamber pressure; and the other variable floating plate capacitor is active when the atmospheric pressure is less than the historical reference chamber pressure. The historical reference chamber pressure is constantly being equalized to the real time atmospheric pressure by an orifice that leaks air into, or out of the chamber at a delayed rate. 
     The electronic value of the variable, floating plate capacitors are read by a computer program that uses a time reference to measure the electrical discharge of the capacitors through a resister. The computer program uses the difference between two variable, floating plate capacitor electrical values, separated by a time delay, to determine the rate-of-change of the atmospheric pressure. 
     The computer program compares the values received with preset alarm level set for the computer alarm looping program. These preset alarm values are formulated from historical storm testing data and are used to trigger the device alarm. Activation of the device alarm is an indication of the existence of atmospheric conditions favorable to possible adverse weather conditions. 
     At the end of each computer detection and/or alarm cycle, the program resets to zero and another series of time slice values are processed for alarm indications. 
     The device is fitted with an RCA plug for providing the device output values to an A/D converter that may be used to connect to other devices such as a computer. 
     The feasibility of the present invention was determined when a considerable amount of distinctive atmospheric pressure pulsing was detected prior to the arrival of a serious weather squall line. A sharp rise in atmospheric pressure followed, with the storm event arriving later in the time frame. The sudden increase in the pulsing of the atmospheric pressure prior to a serious storm event was selected for the alarm trigger of this invention. 
     When the system is turned on, it performs an operational self test an then starts a continuous atmospheric rate-of-change monitoring. The system constantly subjects two, dual diaphragm operated, variable, floating plate, capacitors connected to atmospheric pressure. One variable capacitor has atmospheric pressure ducted to the space between the capacitor operating diaphragms, with the external surface of the same diaphragms being subject to the pressure in a historical reference chamber. The other variable, floating plate, capacitor has reference chamber pressure ducted to the space between the capacitor operating diaphragms, with the external surface of the same diaphragms being subjected to the atmospheric pressure. 
     Pulses in the atmospheric pressure, greater than or less than the historical reference chamber pressure, will cause one of the variable capacitors to compress and increase in electronic value; and the other to decompress and decrease in electronic value. 
     Each variable, floating plate capacitor is connected by a pair of wires to a circuit board that has a programmable language called PBASIC programmed to read the electrical value of each variable capacitor by timing the discharge time,through a fixed resistor. The program uses integer math for all calculations and no values less than one are calculated. The power supply is a 9 volt battery. 
     The PBASIC program reads the values of each variable capacitor and stores the value in a memory. After a time delay of 10 milliseconds, the program reads the variable capacitors again and calculates the rate of change over the time delay with integer mathematics. These rate-of-change calculations are summed and stored in a single memory and a loop counter is increased one integer. The program is attached hereto as Appendix “A”. An accompanying flow chart is Appendix “B”. 
     Construction 
     With respect to the drawings, the atmospheric pressure deviation sensor according to the invention is illustrated at numeral  10  in FIG.  1 . Sensor assembly  11  is shown pictorially and includes a reference chamber  14  housing a sensor  15  that provides electrical signals to processing assembly  12 . Another sensor  16  is subject to atmospheric pressure as indicated by the arrows and is connected to reference chamber  14  via duct  18 . Sensor  15  is connected to the atmosphere via duct  17 . Pressure inside the reference chamber is controlled by wick vent  19  that functions as a very small orifice. 
     As atmospheric pressure increases to “high”—a value higher that it has been in the immediate past—sensor  15  provides an output signal to processing assembly  12 . At the same time, sensor  16  also sends a signal output to assembly  12  where electric circuitry and a computer program will process the output signals. 
     FIGS. 2 and 3 are pictorial illustrations of the sensors  15  and  16  of FIG. 1 with different atmospheric conditions. FIG. 2 represents a steady state condition. FIG. 3 represents a condition where the atmospheric pressure has dropped in the past few minutes. Wick vent  19  can be adjusted to equalize pressure in the reference chamber  14  with atmospheric pressure in the range of approximately 10-60 seconds as desired. 
     FIG. 4 illustrates a pictorial cross-sectional view of the sensor assembly  11  as actually constructed. Plastic cover plates  20 ,  21  and plastic partition wall  22  define the interior spaces of body  23  which is a section of PVC pipe which is a 3 inch coupling and approximately 4 inches in diameter. Reference chamber  14  is defined by upper cover plate  20 . Housing  23  and partition wall  22 . Pressure sensor  15  has a sensor ring  25  that is glued to a sensor support ring  26  that is mounted via silicone to the interior side of housing  23 . One end of sensor  15  has duct  17  drilled through ring  25  and housing  23 . Wick vent  19  is a section of insulated stranded #22 AWG copper wire mounted through housing  23 . Output wire holes  24  provide electrical connections between sensors  15  and  16  and circuitry  12 . 
     Below partition wall  22 , sensor  16 , having sensor ring  28 , is mounted to sensor support ring  27  attached with silicone to housing  23 . Duct  29  drilled through ring  28  is the same as duct  17 . Both sensors  15  and  16  are constructed to be as identical as practically possible. In addition, the sensor assembly  11  is shown horizontally for ease of illustration. In practice, the sensors  15  and  16  will be positioned vertically as will be discussed hereinbelow. 
     The reference chamber  14  is connected to reference chamber header duct  18  which includes ducts  29  to sensor  16  and ducts  30  and  31  to opposite sides of sensor  15 . In practice, header duct  18  is formed by drilling through housing  23  top to bottom and then drilling horizontally through housing  23  to form ducts  29 ,  30 , and  31 . Accordingly, the ends of header  18  are sealed by cover plates  20 ,  21  which are secured via a bead of silicone (not shown) and a piece of duct tape  34  on the outside as shown. 
     At the other side of housing  23  a groove  35  is cut to connect the ducts to atmosphere  17 ,  19 ,  32 ,  33  in a manner whereby a filter  36  can be used to protect the interior of housing  23  from dust and debris. Test hole  37  is used for testing and shipping and is normally sealed closed with a cap screw (not shown). 
     FIG. 5 is a partially exploded pictorial view of a single sensor  15  or  16  which are constructed to be identical. Diaphragm stop plates  38  have center holes  39  to allow air pressure to push on mylar diaphragms  40 . The floating plate capacitors used in the sensors  15 ,  16  are illustrated as numbered for convenience. Twelve thin metal plates  41  are stacked into two groups of six plates forming two variable capacitances. 
     Spacers  42  are circular rings made of insulating material. The plates  41  are covered on one side by an insulating plastic material that also covers solder connection  49  to which individual copper wires  48  are attached on one side of a plate  41 . Pressure sensor spring  43  provides for separation and mechanical balancing of the plates  41  as will be discussed hereinbelow. Diaphragm stop plates  38  limit the travel of plates  41  and are secured to diaphragms  40  and ring  44  with contact cement. 
     Sensor ring  44  has duct  50  and two wire holes  45 , one tilted upwardly and the other holes are for the output wires  48  from the twelve capacitor plates  41  in a sensor. A hole  50  is a vent and indicated by one of the markings  52  that function as a guide to installation of the ring  44  and the plates  41  with the attached wires  48 . Holes labeled “C” are used in the assembly process for holding the spring-loaded plates  41  in place while the diaphragm  40  and stop plate  38  are mounted and sealed with contact cement. Copper wires are temporarily mounted across the plates  41  between two “C” holes and one “C” hole and vent hole  50 . When assembly is complete the additional wires are removed and all holes but vent  50  are sealed closed with silicone. 
     Wires  48  are collected and soldered downwardly as a matter of fabrication convenience. Seal hole  47  is filled with silicone or other sealant upon completion of running the wires  48  through vertical slot  46 . Wires  48  form two 6-wire bundles. 
     FIG. 6 illustrates a top view of the assembly  11  showing the relative position of several features of the sensor assembly  11 . 
     FIG. 7 illustrates a top view of a sensor ring and its relation to the output signal wiring. The ring  25 ,  28  or  44  is formed of a section of PVC pipe and is attached inside of housing  23 . The ring  44  has  16  holes drilled through it. Twelve of the as shown. The two output wires are fitted through holes  24  as illustrated in FIG.  6 . Sensor rings  25 ,  28  are mounted in sections of interior housing that have been cut out. This allows for silicone between the exterior surface of the rings and the housing to provide for sufficient elasticity to prevent ambient temperature changes from adversely affecting sensor operation. 
     Sensor spring  43  is illustrated in FIG.  8 . The spring  43  consists of a planar ring of copper similar to that of capacitor plates  41 . A sheet metal break is used to create alternating pleats or creases  54  that result in a sawtooth-like profile. 
     FIG. 9 illustrates the basic stamp circuit board  55  (a product of Parallax, Inc. of California). The board  55  includes 9 volt battery clips  60 , programming input circuitry  61 , RAM-based PBASIC language chip  62  which is connected to input/output header  63 , and a prototyping area for user-selectable circuits. 
     FIG. 10 illustrates the circuitry used in the present invention in prototyping area  64 . Circuit ground  65  is attached at pin GND. Resistors  66 - 72 , switch  73 , whistle alarm  74 , buzzer  75 , transistors  76 - 77  and LED&#39;s  78  and  79  are all standard components known in the art. 
     Pin  1  connects to negative pressure sensor  15  located in reference to chamber  14 . Pin  2  is an optional connection to chart recorders and other equipment as desired. Pin  7  connects to positive pressure sensor  16  via calibration resistor  70 . 
     To operate the system: 
     1. Set the housing  23  on end and turn the rocker switch  73  ON. 
     2. The system  10  will perform as follows; 
     a) The device will test the lights  78 ,  79  and the alarms  74 ,  75 . 
     b) The device will initialize memory. 
     3. Low atmospheric pressure wave activity will be indicated by a flash of the green light  79  every  17  seconds. 
     4. Medium atmospheric pressure wave activity will be indicated by a single signal from red light  78  every  4  seconds with an occasional sound of buzzer  75 . 
     5. Strong atmospheric wave activity will be indicated by  10  sounds of the electronic whistle  74 . 
     6. At the end of each alarm cycle the device will reset to the detection mode. To test the device when it is operating, turn switch  73  OFF and wait  30  seconds. Turn the device ON. 
     7. Low battery voltage will be indicated by a chirping of whistle  74 . 
     While the invention has been described with respect to certain specific embodiments, it will be appreciated that many modifications and changes may be made by those skilled in the art without departing from the spirit of the invention. It is intended therefore, by the appended claims to cover all such modifications and changes as fall within the true spirit and scope of the invention.