Abstract:
A level detector mounts to a tank containing a liquid. The detector transmits and receives ultrasonic pulses. The pulses are processed by a microprocessor which periodically measures the liquid level of the tank. When the liquid level reaches a pre-established level, a cell phone automatically transmits data to a remote location. A schedule for emptying the tank is generated by a server at the remote location. A service man uses the schedule to visit the tank location and empty the tank. In addition, a portable charger/calibrator is mounted to the level detector to charge the power supply of the detector and calibrate the liquid level.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the priority of U.S. Provisional Patent Application No. 61/596,856 filed on Feb. 9, 2012, the disclosure of which is incorporated by reference in its entirety. 
     
    
     BACKGROUND 
       [0002]    This disclosure relates generally to devices and methods for determining the liquid level in a tank. More particularly, this disclosure relates to electronic devices for automatically determining the liquid level in a tank. 
         [0003]    For applications to which the present disclosure relates, waste oil from restaurants and food preparation facilities has now become a significant source of fuel. The waste oil is typically stored in tanks at the restaurant or facility. When a sufficient quantity of waste oil has been accrued, the waste oil is picked up and transferred to a tank on a truck. The waste oil is taken to a refining facility wherein the waste oil is filtered and/or otherwise treated to produce fuel suitable for usage. 
         [0004]    One of the recurring issues is to schedule the trucks and pickup events so that a proper amount of waste oil is on hand for pickup. Economic considerations dictate that there be sufficient quantities of waste oil available for pickup subject to the limiting parameters that the pickup should not be scheduled beyond the point when the waste oil tank is full of waste oil. 
       SUMMARY 
       [0005]    Briefly stated, the level detector/transmitter system comprises a level detector which includes a housing adapted to mount to a tank for liquid having a level within the tank. The detector also comprises a power supply, a microprocessor, a cell phone in communication with the microprocessor and an ultrasonic transceiver adapted to transmit pulses and receive echoes of the pulses and to transmit signals relating to the pulses to the microprocessor. The microprocessor processes the data to measure the liquid level of the tank. The microprocessor also regulates the time between measurement of the liquid level in the tank and controls the operation of the cell phone for transmitting data indicative of the liquid level in the tank when the liquid level reaches a pre-established threshold. The detector/transmitter system comprises a portable charger/calibrator which is adapted to mount onto the level detector and to charge the power supply of the level detector, as well as to calibrate the liquid level as measured by the microprocessor of the detector. 
         [0006]    The portable charger/calibrator comprises a plurality of switches indicative of various level values of the tank. The detector comprises a pair of contacts and the portable charger/calibrator comprises a pair of contacts which engage the contacts of the liquid detector to provide electrical communication therewith. The portable charger/calibrator includes a charge lamp for indicating the charge status of the level detector. 
         [0007]    The detector/transmitter system also employs a remote server which receives data from the cell phone of the level detector and generates a schedule for a stop for emptying and transporting liquid from the liquid container tank. The power supply is monitored and the microprocessor activates the cell phone to transmit a signal indicative of a low power supply. The microprocessor transforms the level detector to a sleep mode between measurements. 
         [0008]    A level detector/transmitter system for automatically measuring the liquid level of the tank also may employ two ultrasonic transceivers each adapted to transmit pulses and receive echoes of the pulses. The signals relating to the pulses are transmitted to the microprocessor which derives a measurement of the liquid level of the tank. The microprocessor also regulates the time between measurement of the liquid level in the tank and controls the operation of the cell phone for transmitting data indicative of the liquid level in the tank when the liquid level reaches a pre-established threshold. After the liquid has been removed from the tank, a portable charger/calibrator is mounted onto the level detector to charge the power supply of the level detector and to calibrate the liquid level as measured by the microprocessor. 
         [0009]    A method for monitoring a liquid level of the tank comprises employing a level detector to automatically, intermittently measure the liquid level of the tank. Upon the measured liquid level reaching a pre-established threshold, data is automatically transmitted to a remote location. The transmitted data is employed to determine when the liquid should be removed. The liquid is removed from the tank, the level detector is then charged, and the liquid level measurement of the level detector is then calibrated. 
         [0010]    The data is preferably transmitted by a cell phone. The liquid level is preferably measured by emitting pulses from an ultrasonic transducer and processing the echo pulses in a microprocessor. The steps of charging and calibrating the level detector are immediately preceded by mounting a portable charger/calibrator to the level detector. The charger/calibrator is then removed at the conclusion of the charging and calibrating steps. The pre-established threshold level is approximately three-fourths of the volume of the tank in one embodiment. 
         [0011]    In a preferred embodiment of the method, a multiplicity of level detectors each mounted to one of a plurality of tanks generate and transmit data to a central server. A service schedule for emptying the tanks is automatically generated by the server. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is a perspective view of a level detector; 
           [0013]      FIG. 2  is a perspective view of the level detector of  FIG. 1 , taken from a generally opposite position thereof; 
           [0014]      FIG. 3  is a frontal view, partly in phantom, of the level detector of  FIG. 1 ; 
           [0015]      FIG. 4  is a top plan view, partly in phantom, of the level detector of  FIG. 1 ; 
           [0016]      FIG. 5  is a side view, partly in phantom, of the level detector of  FIG. 1 ; 
           [0017]      FIG. 6  is a perspective view of a portable charger/calibrator for the level detector of  FIG. 1 ; 
           [0018]      FIG. 7  is a perspective view of the portable charger/calibrator of  FIG. 6  as mounted to the level detector of  FIG. 1 ; 
           [0019]      FIG. 8  is a rear view, partly in phantom, of the portable charger/calibrator and level detector of  FIG. 7 ; 
           [0020]      FIG. 9  is a top plan view, partly in phantom, of the portable charger/calibrator and level detector of  FIG. 7 ; 
           [0021]      FIG. 10  is a side view, partly in phantom, of the portable charger/calibrator and level detector of  FIG. 7 ; 
           [0022]      FIG. 11  is a schematic diagram of a level detector/transmitter system employing the portable charger/calibrator of  FIG. 7 ; 
           [0023]      FIG. 12  is a timing diagram for the calibration function of the detector/transmitter system of  FIG. 11 ; 
           [0024]      FIG. 13  is a timing diagram for the monitor mode function for the detector/transmitter system of  FIG. 11 ; and 
           [0025]      FIG. 14  is a schematic diagram for the flow and processing of data for the detector/transmitter system of  FIG. 11 . 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    With reference to the drawings wherein like numerals represent like parts throughout the several figures, a level detector/transmitter system employs a level detector  10  and a portable charger/calibrator  12  which cooperate to calibrate the liquid level of a tank such as a waste oil tank, to monitor the level of the tank and to transmit data indicative of the liquid level of the tank. The charger  12  also functions to charge the battery of the level detector  10 . A level indicator  10  is installed at each of the tanks to be serviced. 
         [0027]    The level detector  10  comprises a housing  20  which includes a forward coupler  22  with a stop  24 . Coupler  22  facilitates the mounting of the detector to a bung hole or a tapped opening at the top of a tank  14 , schematically illustrated in  FIG. 11 . The housing  20  has a projecting portion  30  which, upon installation, extends exteriorly of the tank. The housing has a pair of sides  32  and  34  which exteriorly mount opposed conductive clips  36  and  38 . The projecting portion also includes a centrally positioned rectangular rail  40 . The rail is preferably affixed with a serial number  42  for identification purposes. 
         [0028]    With reference to  FIG. 11 , the level detector  10  employs at least one ultrasonic transceiver  50  which transmits ultrasonic pulses and receives their echoes from the surface of the liquid in the tank to determine the liquid level of the tank. The detector is powered by a pair of batteries  52  which connect to a power control circuit  54  and a timing circuit  56 . A microprocessor  60  controls the power via a FET switch  62  to a cell phone  70  which intermittently transmits data indicative of liquid level readings and/or a low battery condition of the level detector  10 . The contacts  36  and  38  communicate via a pulse detector  66  for calibrating and charging the level detector. A voltage regulator  68  supplies pulses via a FET switch  72  to the ultrasonic transceiver  50 . 
         [0029]    The echo pulses are then transmitted to the microprocessor  60  and processed to derive data indicative of the liquid level of the tank. The data is then transmitted via the cell phone  70  to a server  200  which is typically located at a remote site. The detector microprocessor  50  measures the time differential between the reflection and the return of the echo pulse and correlates the time differential with a pre-established tank level. The volume of the liquid level may thus be essentially calculated from the differences in the times of transmission and reception of a given pulse. 
         [0030]    The portable charger/calibrator  12  includes a housing  100  which has a slot  102  dimensioned to be generally complementary to the detector exterior housing portion  30  so that the portable charger/calibrator may mount over and receive the housing exterior portion  30  of the transmitter housing, as best illustrated in  FIG. 7 . The front face  110  of the charger/calibrator for one embodiment includes five buttons  111 - 115  which respectively designate full, ¾, ½, ¼ and empty tank conditions. Other level conditions and corresponding buttons are also possible. In addition, the front face includes a charging indicator  118  in the form of an LED. The indicator  118  pulses to indicate “charging” and illuminates in a steady state to indicate a “full charge”. 
         [0031]    Electrical communication between the charger/calibrator  12  and the level detector  10  is established via internal convex contacts  106  and  108  which respectively engage the exterior contacts  36  and  38  of the level detector. The portable charger/calibrator  12  includes a battery power supply  120  which communicates via a charging circuit  122  to charge the batteries  52  of the level detector when the contacts  36 ,  106  and  38 ,  108  are engaged and charging is required. The buttons  111 - 115  connect via corresponding switches  121 - 125  which provide input to the microprocessor  130 . The microprocessor  130  has a port which communicates via a FET switch  132  for generating pulses for calibrating the level detector. 
         [0032]    The portable charger/calibrator  12  is transportable by the driver of the service truck. The charger/calibrator  12  is charged through the charger circuit  124  via the cigarette lighter outlet of the service truck. 
         [0033]    The level detector  10  is generally permanently mounted to the top of the waste oil tank. When the serviceman arrives at the site of the tank, he visually determines the approximate liquid level of the tank. He places the charger calibrator  12  over the level detector  10  and presses the appropriate button  111 - 115  on the face of the calibrator  12 . Pulses are emitted from the transceiver  50  toward the surface of the liquid. The echo pulses are received by the transceiver, and the timing delay is determined to get a calibration point for the correlated level, for example, ¾ level full. After the tank is emptied, the serviceman presses the “empty” button  115  so that a calibration of the pulse time delay for the empty tank is determined. In this fashion, a calibration is made each time the tank is emptied, and the microprocessor  50  of the detector  10  is appropriately adjusted to reflect the calibration. 
         [0034]    With reference to  FIG. 12 , when the charger/calibrator  12  is attached to the level detector  10 , the voltage level is established. A single pulse is then generated to indicate the start, and the charge gradually ramps up to a full charging condition for the level detector. A series of pulses are then indicated on the charger lamp  118  until the full charging condition has been established and a steady state illumination is generated. 
         [0035]    The “full” level switch generates a series of pulses, and the “empty” level switch generates a single pulse. The time delays of the echo between the “full” level switch and the “empty” level switch are then determined. Pulses are generated at the end of the time delay. These pulses are then stored as measurements of the “full” level and the “empty” level condition of the tank level. Intermediate levels can also be mathematically derived. 
         [0036]    With reference to  FIG. 13 , the level detector  10  does not continuously operate, but operates in an intermittent sleep/active mode to conserve power. After the charger calibrator  12  is attached, there is typically a 48 hour delay timer. Each 48 hours, the level detector via microprocessor  60  and ultrasonic transceiver  50  measures the level and compares the measured level with the correlated levels stored in the microprocessor. When the measured level exceeds ¾ full, for example, the restart delay timer is activated and data indicative of the measured level is transmitted via the cell phone  70  to the server  200  at pre-established time periods. 
         [0037]    Prior to the serviceman returning to the truck, the charger/calibrator  12  is removed from the level detector  10  and the IP address or serial number  42  on the level detector is noted. The portable charger/calibrator  12  remains with the serviceman. The serviceman then transmits on his cell phone  300  the number together with the data and puts the number in an application  310  on his cell phone. The serviceman then together with the GPS position, the inputted name, address, contact and telephone number of the facility hits “send” on the cell phone application  310 . The information is now in the database and available to the remote server  200 . 
         [0038]    It will be noted that when the charger/calibrator  12  is removed from the level detector  10 , there is a pre-established time delay which is typically two days. At the end of the two-day period, the level detector  10  takes a measurement. If the tank is less than ¾ full, the detector essentially sleeps until the next reading, which is two days later. Other pre-established trigger levels may also be employed. 
         [0039]    When the ¾ tank reading has been acquired, data information is transmitted to the server  200  together with the identification of the restaurant and the battery service condition of the transmitter. If the battery  52  is low, a battery level signal is transmitted immediately. The serviceman will then immediately go and pick up the waste oil and recalibrate and recharge the level detector  10 . It will be appreciated that the level detector  10  is recalibrated (and potentially recharged) every time the tank is emptied. 
         [0040]    In a preferred application of the detector/transmitter system, numerous level detectors  10  are installed in tanks at various locations. The data generated is transmitted via cell phone to a single remote server  200 . 
         [0041]    Based on the transmittal of information from each of the separate facilities, the server  200  will generate a route  400  together with GPS readings in electronic form and/a paper form so that the serviceman will be routed in the appropriate fashion to the various pick up points to empty the containers and collect the waste oil. The serviceman will then employ the portable charger/calibrator  12  to charge and calibrate each level detector after liquid has been removed. 
         [0042]    While a preferred embodiment of the foregoing has been set forth for purposes of illustration, the foregoing description should not be deemed a limitation of the invention herein. Accordingly, various modifications, adaptations and alternatives may occur to one skilled in the art without departing from the spirit and the scope of the present invention.