Closed air pressure system having an emergency shut off

Abstract

There is provided an emergency motor shut off for a closed air system having a low pressure threshold and a high pressure threshold. In a preferred embodiment, the closed air system includes a compressor and motor for charging the pressure of the system. Typically, any suitable electric power source provides power to the motor. A pair of electric contactorss electrically disposed between the power source and the motor are pneumatically controlled to allow electric current to either pass through or to prevent current from reaching the motor. A timer determines the run time for a single run cycle of the motor. A shut off that is responsive to the timer impedes the flow of electric current to the motor after a predetermined amount of run time. The timer is reset to zero after each run cycle of the motor. Typically the shut off comprises a relay timer having an internal relay. The invention also provides for an alarm to signal when the system when the predetermined amount of time is reached on the timer.

What is claimed is:  
     
         1 . A closed air system having a low pressure threshold and a high pressure threshold, said closed air system comprising: 
 compression means for raising the pressure of said system;    a motor for driving said compression means;    an electric power source for providing electric current to said motor;    timing means for determining the run time for a single run cycle of said motor;    an emergency shut off means that impedes the flow of electric current to said motor, said emergency shut off means responsive to said timing means; and    timing reset means for resetting the run time to zero after each run cycle of said motor.    
     
     
         2 . The system of  claim 1 , wherein said timing reset means includes a counter and at least one electric contactor, wherein the run time is reset to zero when said at least one electric contact opens.  
     
     
         3 . The system of  claim 1 , wherein said emergency shut off means further includes at least one relay electronically disposed between said power source and said motor, said relay opening after a predetermined run time is determined by said timing means.  
     
     
         4 . The system of  claim 3 , further including bypass means for bypassing said emergency shut off means.  
     
     
         5 . The system of  claim 1 , further including at least one alarm, said alarm responsive to said emergency shut off means.  
     
     
         6 . A method for protectively shutting down a closed pressure system wherein the system fails to charge to a high pressure threshold after a predetermined charging time, wherein a motor driven compressor begins raising the air pressure once the air pressure of the system reaches a low pressure threshold, said method comprising: 
 counting means for determining an amount of run time of a single run cycle of the motor;    resetting means for resetting the counting means to zero if a predetermined run time is not reached during the single run cycle of the motor; and    shutting down said motor after a predetermined amount of time is determined by said counting means during said single run cycle of said motor, wherein said predetermined amount of time is greater than the time it normally takes for the system to properly charge to the high pressure threshold.    
     
     
         7 . The method of  claim 6  wherein said setting a timing means further includes the step of cutting power to a timing relay device.  
     
     
         8 . The method of  claim 6  wherein said determining the run time of a single run cycle of said motor further includes the step of determining the amount of time that continuous electric current passes through a timing relay device.  
     
     
         9 . The method of  claim 6  wherein electric current running from a power source through a timing relay device controls the motor, and wherein the step of shutting down said motor further includes the step of opening at least one internal relay of said timing relay device.  
     
     
         10 . The method of  claim 6  further including the step of signaling an alarm after said shutting down step.  
     
     
         11 . A closed air system having a low pressure threshold and a high pressure threshold, said closed air system comprising: 
 compression means for raising the pressure of said system;    a motor for driving said compression means;    an electric power source for providing power to said motor;    at least one electric contactor electrically disposed between said power source and said motor;    a pressure determining means for determining the pressure of said system;    a first shut off means which opens said at least one electric contact, said first shut off means responsive to said pressure determining means;    timing means for determining the run time for a single run cycle of said motor;    a second shut off means that impedes the flow of electric current to said motor, said second shut off means responsive to said timing means; and    timing reset means for resetting the run time to zero after each run cycle of said motor.    
     
     
         12 . The system of  claim 11 , wherein said timing reset means includes a counter and at least one electric contactor and the run time is reset to zero when said at least one electric contactor opens.  
     
     
         13 . The system of  claim 11 , wherein said second shut off means further includes at least one relay electronically disposed between said power source and said motor, said relay opening after a predetermined amount of time is determined by said timing means.  
     
     
         14 . The system of  claim 13 , further including bypass means for bypassing said shut off means.  
     
     
         15 . The system of  claim 11 , further including at least one alarm, said alarm responsive to said second shut off means.  
     
     
         16 . The system of  claim 11 , further including closing means that closes said at least one electric contact when the system air pressure reaches the low pressure threshold.  
     
     
         17 . The system of  claim 11 , further including opening means that opens said at least one electric contact when the air pressure reaches the high pressure threshold.