Abstract:
A wireless pump on/off system incorporates a radio receiver and an antenna. An RFID tag is carried on a float. The float can be located in a fluid whose level is to be controlled with at least a portion thereof protruding above the fluid level. Signal strength of a wireless received from the tag can be indicative of at least one fluid level, and responsive thereto a pump can be activated. The pump can be deactivated in response to another received wireless signal, loss of the activating signal indicative of another fluid level or expiration of a preset time interval.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of the filing date of U.S. Provisional Application Ser. No. 61/034,064 filed Mar. 5, 2008 and entitled “Radio Float Liquid Level Detection System”, incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The invention pertains to pump control systems. More particularly, the invention pertains to such systems which detect pump on/off levels of a liquid using a floating RFID tag. 
       BACKGROUND 
       [0003]    Various types of level detection systems are known to control on/off pump cycles. These include mechanical as well as non-mechanical level sensors. Examples include various types of known float or diaphragm switches. Known mechanical sensors while useful suffer from wear and mechanical stresses. 
         [0004]    Non-mechanical level sensors are known and are improvements over the mechanical units. However known non-mechanical units require routine maintenance as they are affected by their environment and can suffer from contaminant build-up, mold, dirt, corrosion was well as contaminating liquid or moisture. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]      FIG. 1  is a block diagram of a single antenna pump control unit which embodies the invention; 
           [0006]      FIG. 1A  is a flow diagram of processing in the system of  FIG. 1 ; 
           [0007]      FIG. 2  is a block diagram of another single antenna pump control unit which embodies the invention; 
           [0008]      FIG. 2A  is a flow diagram of processing in the system of  FIG. 1 ; 
           [0009]      FIG. 3  is a block diagram of a dual antenna pump control unit which embodies the invention; 
           [0010]      FIG. 3A  is a flow diagram of processing in the system of  FIG. 1 ; 
           [0011]      FIG. 4  is a block diagram of a single antenna level notification unit which embodies the invention; 
           [0012]      FIG. 4A  is a flow diagram of processing in the system of  FIG. 1 ; 
           [0013]      FIG. 5  is a block diagram of a multiple antenna level notification unit which embodies the invention; and 
           [0014]      FIG. 5A  is a flow diagram of processing in the system of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    While embodiments of this invention can take many different forms, specific embodiments thereof are shown in the drawings and will be described herein in detail with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention, as well as the best mode of practicing same, and is not intended to limit the invention to the specific embodiment illustrated. 
         [0016]    Embodiments of the invention sense liquid levels non-mechanically so as to substantially eliminate maintenance during the life of the respective unit. In one aspect of the invention, a float can carry a radio frequency identification (RFID) tag. Radio signals from the tag, as the float moves up and down in response to level of the associated liquid, can be used to sense how far the float is from a receiving antenna, which can be fixed relative to liquid level. 
         [0017]    A single sensing antenna can be used in one embodiment. As the level increases, the float moves closer to the antenna. When signal strength crosses a predetermined threshold, a pump can be activated to pump the level down. In one aspect, pumping can be terminated after a pre-determined time interval. In another aspect, pumping can continue until signal strength from the floating tag falls below a predetermined level. 
         [0018]    In another embodiment, two spaced apart antennas can be used to establish that the float is near either a lower level or an upper level. In yet another aspect of the invention, additional antennas can be provided to sense a pre-flood condition. 
         [0019]    The antenna(s) can be coupled to a receiver and control circuits to establish when to turn the pump on and off based on signals from the RFID tag on the float. Activating RF signals can be transmitted into the vicinity of a passive-type tag to energize same. 
         [0020]    In another aspect of the invention, multiple RFID tags can be floated simultaneously, on a common float or different floats to provide redundant level control signals. In the following discussion of the figures, the same identification numerals are used on various figures for common elements. 
         [0021]      FIG. 1  illustrates an RFID system  10  with one “waterproof” antenna  12  to detect an increasing liquid level and control a pump (like a residential sump pump)  14 . It uses a method of antenna-to-RFID tag proximity to sense a liquid&#39;s level. An RFID tag  18  is part of a floating housing  20  which is kept from drifting away from the antenna  12  via stationary guides or a tube  22 . The antenna  12  may also be attached to the guide(s)  22 . When the tag  18  is close enough to be read by an RFID electronic controller  26  via its antenna  12 , pump  14  can be turned on to empty the “container” or pump c as a predetermined liquid level has been reached. Once the electronic controller  26  can no longer communicate with the tag  18 , the attached pump  14  is turned off. 
         [0022]    In another variation of system  10  the electronic controller  26  can turn a “filling” pump off when the tag  18  can communicate with the controller; and then turn it back on when communication is lost. This would be useful in applications such as a city water tower, or other reservoir.  FIG. 1A  is a flow diagram which illustrates exemplary processing carried out by system  10 . 
         [0023]      FIG. 2  illustrates an implementation 30 that uses an RFID system  30  with one “waterproof” antenna  12  and a timer  26   a  to detect an increasing liquid level and control a pump (like a residential sump pump)  14 . An RFID tag  18  is part of a floating housing  20  which is kept from drifting away from the antenna  12  via stationary guides or a tube  22 . The antenna  12  may also be attached to the guide(s)  22 . When the tag  18  is close enough to be read by the RFID electronic controller  26  via its antenna, a pump  14  can be turned on to empty the “container” or pump c since the predetermined liquid level has been reached. After a predetermined period of time (counted down by a timer  26   a  inside the electronic controller  26 ), the pump  14  is turned off. 
         [0024]    In another variation of system  30  the electronic controller  26  turns a “filling” pump off when the tag  18  can communicate with the controller; and then turns it back on after a predetermined period of time (counted down by a timer  26   a  inside the electronic controller). This could be useful in applications such as a city water tower, or other reservoir.  FIG. 2A  is a flow diagram which illustrates exemplary processing carried out by system  30 . 
         [0025]      FIG. 3  illustrates an RFID system  40  with two “waterproof” antennas  42   a,b  and a discharge pump  14  to keep an increasing liquid level within a predetermined height range (as in a residential sump pit). An RFID tag  18  is part of a floating housing  20  which is kept from drifting away from the antennas  42   a,b  via stationary guides or a tube  22 . The antennas  42   a,b  may also be attached to the guide(s)  22 . When the tag is close enough to be read by the RFID electronic controller  26  via its topmost antenna  42   a , a pump  14  can be turned on to discharge liquid from the “container” or pump c. The pump  14  is turned off when the electronic controller  26  can communicate with the tag  18  via its bottommost antenna  42   b.    
         [0026]    In another variation of system  40  the electronic controller  26  turns a “filling” pump off when the tag  18  can communicate with the controller via its topmost antenna  42   a ; and then turns it back on when the controller can communicate with the tag via its bottommost antenna  42   b . This would be useful in applications such as a city water tower, or other reservoir.  FIG. 3A  illustrates a flow diagram of exemplary processing carried out by system  40 . 
         [0027]      FIG. 4  illustrates an RFID system  50  with one “waterproof” antenna  52  to detect an increasing liquid level and then initiate an appropriate notification. An RFID tag  18  is part of a floating housing  20  which is kept from drifting away from the antenna  52  via stationary guides or a tube  22 . The antenna  52  may also be attached to the guide(s)  22 . When the tag  18  is close enough to be read by the RFID electronic controller  26  via its antenna  52 , a notification or alert A (such as an alarm notice) can be initiated as the predetermined liquid level has been reached. These notifications are triggered by the electronic controller  26  and can be audible or visual, including buzzers, lights, emails, etc. They can be activated immediately or after a predetermined period of time (counted down by a timer such as  26   a  inside the electronic controller  26 ). 
         [0028]    In a variation of system  50  the electronic controller  26  initiates a notification when it is unable to communicate with the tag  18 , that is, when the fluid level has fallen below a predetermined level.  FIG. 4A  is a flow diagram which illustrates exemplary processing carried out by system  50 . 
         [0029]      FIG. 5  illustrates an RFID system  60  with a plurality of “waterproof” antennas  62   a,b,c , . . . , to incrementally measure a liquid&#39;s level L. An RFID tag  18  is part of a floating housing  20  which is kept from drifting away from the antennas  26   i  via stationary guides or a tube  22 . The antennas  62   a,b  . . . , may also be attached to the guide(s)  22 . When the tag  18  is close enough to be read by the RFID electronic controller  26  via an antenna  62   i , the controller can respond to the liquid level being closest to that antenna  62   i  and can act appropriately. Reaction to this monitoring can be an audible or visual notification or alert A, and/or automatic control over a process or machine, like a pump or valve, etc.  FIG. 5A  is a flow diagram which illustrates exemplary processing carried out by system  60 . 
         [0030]    It will be understood that controller  26  can be implemented, in part, with a programmable processor  26   b  and executable control software  26   c , best seen in  FIG. 1 . The software  26   c  can be stored in computer readable storage units such as read-only or read-write memory. Processor  26  in combination with software  26   c  can implement the above-described functionality of systems  10 - 60 . 
         [0031]    From the foregoing, it will be observed that numerous variations and modifications may be effected without departing from the spirit and scope of the invention. It is to be understood that no limitation with respect to the specific apparatus illustrated herein is intended or should be inferred. It is, of course, intended to cover by the appended claims all such modifications as fall within the scope of the claims.