Patent Application
20090207032
The present invention relates to an apparatus for detecting and announcing when a stortage bin becomes full. An agricultural operation stores the grains it produces in weather proof bins. When the bins are being filled the operator normally monitors the amount in the bin visually so that the bin does not overflow. The present invention, provides a remote indication to the operator when the bin is nearing full.
It is known that if a storage bin overflows while it is being filled, the filling machinery can become jammed and damaged. Also some of the overflowed granular material can be spoilt or lost. A considerable amount of time is required to fill a bin and the operator must remain diligent for the duration.
The present invention allows the operator to rest or work at other tasks, as the bin fills. When a level is reached, that allows time for the operator to return to the bin, a radio signal is sent to a pager like device, causing an audible, tactile and visual alarm to occur. Also when a critical level is reached the invention sends another signal, which causes a second audible, tactile and visual alarm to occur. The operator then shuts the filling machinery off.
Capacitive sensors are used extensively for level measurement and proximity detection. A proximity detector typically determines if materials are near the sensor by comparing the measured capacitance to the predetermined threshold. If the capacitance varies due to environmental changes, this method give false positive or negative detections.
It is known that circuits are available which sense the dramatic change in capacitance when a human finger is placed on a touch pad as taught by Phillip; Harald U.S. Pat. No. 6.452,514. These circuits regularly zero themselves to the current capacitance, thus eliminating drift. These circuits are very low cost. It is also known that Livingston in U.S. Pat. No. 6,539,797 teaches a method of using a separate reference capacitance sensor to correct for change in dielectric of the medium being sensed and that this technique does not work to negate the effects of dust build up, thus producing an erroneous result.
It is known that dust will build up on any surface inside the bin and it has been discovered, by the inventors, that using the Phillip; Harald technique eliminates the problem of dust build up and can be used to detect when a metallic probe is fully immersed in granular material vers covered in a build up of dust.
In the preferred embodiment of the invention, two metallic probes are permanently mounted through the side of the storage bin. One is located near the top of the bin and the other at an appropriate distance below the first probe. Circuits are connected to the metallic probes such that the Phillip; Harald capacitive proximity technique is implemented. A cable connects the resulting two sensors to a connector mounted near the bottom of the bin.
Further circuits are provided in an easily removable housing that can be moved from bin to bin as required. These circuits power the sensors and respond to the detected presence of granular material. This apparatus contains visual annunciation devices and a radio frequency transmitter capable of sending an encoded signal to a remote portable receiver.
Further circuits are provided in a portable, pager like, housing that can be carried by an operator. This apparatus contains a radio frequency receiver capable of receiving the signals sent from the above apparatus connected to the sensor via the cable. It also contains logic and circuits that decodes the signal and visual, audible and tactile annunciation devices to inform the operator of the event of the granular material covering either sensor.
The storage bin level sensing apparatus of the present invention includes one or more capacitive sensors, connected via a common cable to a controller/transmitter which sends a radio status signal to a portable/receiver to alert an operator of a pending over fill condition.
On power on, the apparatus directs power through a cable to the sensors 3 & 4 and enters a delay timer 51. A test, alarm, and signal loop 51 to 58 is then executed periodically when the timer elapses. This loop tests 52 for an electrical signal from the lower sensor which is on if it has detected the presence of granular material, a visual alarm indicator is latched on, a flag is set 54 and control passes to the test for the upper sensor 53. If not, a test 53 is made for an electrical signal from the upper sensor which is on if it has detected the presence of granular material, a visual alarm indicator is latched on, a flag is set 55 and control passes to the test for the low battery 56. If not, the battery voltage is measured 56 and if it is below a fixed threshold, a visual alarm indicator is latched 57 on and control passes to the test radio control logic 58. If not, A radio signal encoded with the status is sent 58 to the portable/receiver 6. If the upper alarm flag is set an upper alarm signal is sent via the radio 58 to the portable/receiver 6 or if the lower alarm flag is set a lower alarm signal is sent via the radio 58 to the portable/receiver 6 or if no alarm flag, are set a no-alarm signal is sent via the radio 58 to the portable/receiver 6. Then the control passed back to the delay timer 51.
If more then 2 sensors are incorporated into the system, duplicates of logic blocks 53 & 55 are inserted between blocks 53 & 55 and the battery test 56.
On power on, the logic starts a delay timer 61. When the timer elapses, the logic tests for low battery voltage 62. If the battery voltage is below a fixed threshold, a visual alarm indicator is latched on 63 and control passes to the data receiver 64. If not, control passes to the data receiver 64. If data has been received, the data is processed 67 ie: decoded and checked if it is valid data. Then the processed data is checked 68 to determine if it represents a new status. If it is a change in status, change 69 the audible, visual and/or tactile alarm indicator states, then the control button is checked 60. If not, check the control button 60. If no data is received, check if radio data has been received in the past 10 seconds 65. If no data has been received for 10 seconds ie: loss of communication, a visual, audible and tactile alarm indicators are latched on 66 and control passes to the control button test 60. If it has been received, then the control button is checked 60.
If the control button is pressed continuously for more then 2 seconds 71, then the power is turned off 72. If the button pressed for less then 2 seconds 73, then any audible and/or tactile alarm indicators are tuned off 74, the timer is reset 61 and the loop starts over. If the control button is not pressed the timer is reset 61 and the loop starts over.
