Abstract:
An insect lure and trap system includes a valve that receives a gaseous fuel, and provides a regulated flow of gaseous fuel. The regulated flow of gaseous fuel is input to an exothermic reactor that generates carbon dioxide to attract insects to a predetermined region, where a generated airflow forces insects within the predetermined region into a container. A temperature sensor senses the temperature of the carbon dioxide and provides a carbon dioxide temperature signal indicative thereof to a controller, which generates a valve command signal that regulates the valve in response to the carbon dioxide temperature signal. Advantageously, operating closed loop on catalyst temperature (i.e., gas temperature measured at the catalyst) allows for a more efficient use of the fuel, which is used to generate the CO 2  attractant.

Description:
PRIORITY DATA 
   This application claims priority from a provisional application filed Feb. 15, 2001 designated Ser. No. 60/268,976 entitled “Insect Lure and Trap System”. This application is incorporated herein by reference. 

   BACKGROUND OF THE INVENTION 
   The present invention relates to the field of devices for trapping insects, and in particular to an insect lure and trap system that uses a carbon dioxide (CO 2 ) attractant. 
   It is known to use a carbon dioxide attractant to lure insects into a trap. For example, U.S. Pat. No. 6,145,243 entitled “Method and Device Producing CO 2  Gas for Trapping Insects” discloses a device for attracting and trapping bothersome flying insects. A problem with this system is that it is manually controlled to turn on and off. Specifically, operation of the system cannot start until the propane-air mixture within a combustion chamber is ignited by a spark. This system is obviously rather cumbersome since it requires manual intervention to initiate system operation. Similarly, the system requires manual intervention to turn the system off. Along with the bothersome requirement of manually turning the system on and off, the system will often undesirably operate when the insects are no longer a factor (e.g., after dark), thus unnecessarily using the propane. 
   U.S. Pat. No. 5,813,166 also discloses a system that employs carbon dioxide attractant to lure insects into a trap. The system includes a control system that allows a user to program the system to turn-on and off based upon a time schedule, or based upon dawn and dusk as sensed by a photocell. The control system includes electronics that turns on and off the flow of carbon dioxide (CO 2 ) from a tank and releases the CO 2  in a constant pulsing pattern to simulate breathing. Specifically, the electronics commands the release of CO 2  into the air for a duration of about 100 milliseconds every two seconds to rhythmically raise and lower the concentration of CO 2  in the vicinity of the trap, similar to the breathing pattern. The control system drives a solenoid valve that opens and closes a flow path for the CO 2 . However, a problem with this system is that it operates open loop and does not regulate the flow of CO 2 . Another problem with this system is that it employs a tank of CO 2  to provide the gas, rather than generating the CO 2 . In addition, the CO 2  is at ambient temperature (i.e., the gas is not heated). 
   Therefore, there is a need for an automatically controlled system that attracts insects using a CO 2  attractant, and traps the insects. 
   SUMMARY OF THE INVENTION 
   Briefly, according to an aspect of the invention, an insect lure and trap system includes a valve that receives a gaseous fuel, and provides a regulated flow of gaseous fuel. The regulated flow of gaseous fuel is input to an exothermic reactor that generates carbon dioxide to attract insects to a predetermined region, where a generated airflow forces insects within the predetermined region into a container. A temperature sensor senses the temperature of the carbon dioxide and provides a carbon dioxide temperature signal indicative thereof to a controller, which generates a valve command signal that regulates the valve in response to the carbon dioxide temperature signal. 
   Advantageously, operating closed loop on catalyst temperature (i.e., gas temperature measured at the catalyst) allows for a more efficient use of the fuel, which is used to generate the CO 2  attractant. 
   These and other objects, features and advantages of the present invention will become apparent in light of the following detailed description of preferred embodiments thereof, as illustrated in the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
       FIG. 1  illustrates a functional block diagram of an insect lure and trap system; 
       FIG. 2  is a simplified illustration of an arrangement of an exothermic reactor, the fuel tank and valve; 
       FIG. 3  is a schematic illustration of the controller; 
       FIG. 4  is a flow chart illustration of the system operation; 
       FIG. 5  is a flow chart illustration of a catalyst pre-heat routine; 
       FIG. 6  is a schematic illustration of an alternative embodiment controller; and 
       FIG. 7  is a schematic illustration of yet another alternative embodiment controller. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  illustrates a functional block diagram of an insect lure and trap system  10 . The system  10  includes a controller  12  that receives a plurality of input signals and controls a plurality of output devices to control the operation of the system. The controller  12  comprises a controller/microprocessor (not shown) that executes program instructions to read the various input signals and control the output devices. 
   The system includes an ambient temperature sensor  14  that provides a signal on a line  16  to the controller  12 , and an ambient light sensor  22  (e.g., a photocell) that provides a signal on a line  24  indicative of the amount of ambient light. A mode select signal on a line  26  is received from a mode select panel  28  that allows a user to select the operating mode of the system. Details of the various modes shall be discussed below. 
   The system also includes an exothermic reactor  30  that generates carbon dioxide (CO 2 ) gas that is used as an attractant. A tank  31  (e.g., removable and disposable) that provides a gas fuel (e.g., propane, butane, methanol, or any low molecular weight paraffin gas) via a flow line  32  to an ON/OFF valve  34 , which receives a valve command signal on a line  38  from the controller. When the valve  34  is open, fuel is released to the exothermic reactor  30 .  FIG. 2  is a simplified illustration of an arrangement of the exothermic reactor  30 . Referring to  FIG. 2 , the fuel from the valve through a catalyst  36 , adjacent to which is positioned a heater  37 . The catalyst  34  may include a ceramic honeycomb material that is coated with platinum or palladium metal. The heater  37  is mounted preferably directly below the catalyst  36 . In one embodiment the heater  37  may be a resistive heating element that receives a pre-heater control signal on a line  40 . The heater  37  is provided to initially heat the catalyst  36  to a point the catalyst can begin the self-sustaining exothermic reaction that generates the CO 2 , as the fuel passes through the catalyst. The control signal on the line  40  commands the heater on and off. A temperature sensor  41  (e.g., a thermocouple) is preferably located above the catalyst  36  to sense the temperature of the CO 2  gas passing through the catalyst, and the temperature sensor  41  provides a temperature signal indicative thereof on a line  20 . 
   Referring again to  FIG. 1 , the trap system  10  also includes a motor  42  that drives a fan  44 , which provides air flow through a screen  46  causing insects to be trapped on an interior side of the screen  46 . The controller  12  provides a motor command signal on a line  48  to the motor  42 . This command signal commands the motor on and off. The motor also drives an impeller  50  located in a flow path of the CO 2  gas, to facilitate exhausting the CO 2 . The system may also include an Octenol reservoir (e.g., removable and replaceable time release cartridge) that releases Octenol to create a CO 2  and Octenol mix. 
   The operation of the catalyst  36  and specifically the generation of the CO 2  is substantially the same as disclosed in U.S. Pat. No. 4,519,776 entitled “Apparatus for Attracting Insects”, assigned to Armatron International, Incorporated, the assignee of the present invention, and incorporated herein by reference. However, unlike the device disclosed in U.S. Pat. No. 4,519,776, the insect lure and trap system of the present invention includes an automatic control system that monitors various sensors and automatically controls the flow of fuel to ensure the system operates only when needed. 
     FIG. 3  is a schematic illustration of the controller  12 . A microcontroller  54  includes executable program instructions to implement the system&#39;s various operating modes. A first resistor bridge  56  is configured and arranged to cooperate with the ambient temperature sensor  14  ( FIG. 1 ), which is preferably a thermistor. A second resistor bridge  58  is configured and arranged to cooperate with the photocell  22  ( FIG. 1 ) to provide a signal indicative of the amount of ambient light to the microcontroller. An oscillator/timer circuit  60  (e.g., an LM555 available from National Semiconductor) controls the fuel valve command signal on the line  38  ( FIG. 2 ) in order to control/modulate the amount of fuel flowing from the tank  31  ( FIG. 2 ). A thermocouple input interface  66  cooperates with the thermocouple  41  ( FIG. 2 ) that senses the exhaust temperature (i.e., the temperature at the catalyst). A sensed temperature signal on a line  64  is provided to the timer  60  to set the rate that the valve  34  ( FIG. 2 ) is opened and closed. That is, the thermocouple  41  ( FIG. 2 ) provides an input signal to the thermocouple interface  66 , and the signal is amplified and filtered, and the resultant amplified signal on the line  62  is input to a comparator  200 . The comparator  200  also receives a reference signal (e.g., 2.5 VDC) on a line  202 . If the value of the amplified signal on the line  62  is greater than value of the reference signal (which is representative of a temperature of about 850° F.) on the line  202 , the comparator  200  (in one embodiment an open collector output device) provides a first output signal on the line  64 , which is input to a capacitor  206 . In this situation, the timer  60  may be configured to command the valve  34  ( FIG. 2 ) to open for a period of about 25 milliseconds, once every second. Of course this frequency and duty cycle are a design choice. As the temperature of the catalyst increases, the value of the amplified signal on the line  62  increases, and the comparator  200  provides a second output signal on the line  64 . As a result, the capacitor  206  is electrically in parallel with capacitor  208 . This causes the timer  60  to provide an output signal on a line  209  that commands the valve  34  ( FIG. 2 ) to open for a period of about 25 milliseconds once every four seconds (i.e., at lower frequency value). Significantly, this control technique intelligently regulates the opening and closing of the valve as a function of catalyst temperature. That is, the flow of CO 2  is controlled as a function of the temperature sensed at the catalyst. The thermocouple  41  ( FIG. 2 ) is mounted in close proximity to the catalyst (e.g., preferably adjacent to and in the flow path catalyst). 
   Referring still to  FIG. 3 , the valve  34  ( FIG. 2 ) is driven by a silicon controlled rectifier  74 . The heater  37  ( FIG. 2 ) is switched on and off by a triac Q 1   76 , while a triac Q 2   78  turns on and off the motor  42  ( FIG. 1 ) that drives the impeller  50  ( FIG. 1 ) to exhaust the CO 2 —Octenol attractant and the fan  44  ( FIG. 1 ) that draws in outside air and mosquitoes. LEDs  80  are provided to indicate the operating mode of the system. 
     FIG. 4  is a flow chart illustration  100  of the system operation. Following a system reset/power-up, step  102  is performed to set the mode equal to 0 and command all the outputs off. Test  104  is performed to determine if the mode is equal 0; if it is, the test  104  is performed regularly to check if the mode has changed. If the mode is not 0, test  106  is performed to determine if the mode is equal to 2, 3 or 4. If the mode is equal to 1, then manual mode operation is initiated, otherwise automatic mode operation begins. 
   Mode 0 is a stand-by mode. Mode 1 is a manual mode. Mode 2 is an automatic mode in which the system comes on at dusk and operates (i.e., dispenses attractant) for three (3) hours. Mode 3 is an automatic mode in which the system comes on at dusk and operates for five (5) hours. Mode 4 is also an automatic mode in which the system operates starting at dusk for a period of three (3) hours, and starting at dawn for a period of two (2) hours. 
   Test  110  checks the ambient temperature, and if the temperature is below a threshold value (e.g., 55° F.), the test  110  is performed periodically to determine if the temperature has increased above the threshold value. Test  111  performs a test to determine if a fixed time has passed (e.g., two hours) since the test  110  was initiated, and if so step  112  is performed to close the fuel valve  34  ( FIG. 2 ) and turn-off the motor  42  ( FIG. 1 ) since the ambient temperature is low. The system then waits until dawn. Once dawn is detected test  114  is performed to determine if the system is configured to operate in mode 4. If it is, a series of steps are performed to command the system to release the attractant if the ambient temperature is high enough. Otherwise, if the system is not in operating mode 4, operation returns to test  104 . 
     FIG. 5  is a flow chart illustration of a preheat routine  500 . This routine includes a step  502  that commands the valve  34  ( FIG. 2 ) to open to start the flow of fuel, and to turn on the heater. A test  504  is then performed to determine if the catalyst temperature is low. Referring again to  FIG. 3 , comparator  210  also receives the amplified temperature signal on a line  62  and compares the value of the signal against a temperature threshold signal on a line  212 . The comparator  210  provides a Boolean signal on a line  214  indicative of whether the amplified temperature signal is above or below the temperature threshold value. Therefore, referring again to  FIG. 5 , the test  504  reads the value of the Boolean signal on the line  214  ( FIG. 3 ) to determine if the temperature is too low. If it is too low, step  506  is performed to check the temperature every ten (10) seconds or so, until the temperature is greater than the threshold value. If the temperature is not greater than the threshold value after a period of time (e.g., ten minutes), then the fuel tank  31  ( FIG. 2 ) may be empty, and step  508  commands the valve  34  ( FIG. 2 ) to close, and the heater  37 ( FIG. 2 ) to turn off. Step  510  is then performed to annunciate this condition by toggling the LEDs  80  ( FIG. 3 ). If the catalyst temperature is determined in test  504  to be above the threshold as indicated by the state of the signal on the line  214  ( FIG. 3 ), then the heater is commanded off, and the motor  42  ( FIG. 1 ) is commanded on. The heater can be turned off since the catalyst is now at a temperature to sustain the catalytic process while fuel is passed through the catalyst. 
   Referring again to  FIG. 3 , the resistor network  56  provides a signal indicative of a sensed ambient temperature signal on a line  222 , to a comparator  224 . The comparator  224  also receives a voltage reference signal on the line  212  that is indicative of an ambient temperature threshold value. The comparator  224  compares the sensed signal on the line  222  against the voltage signal on the line  212  and provides a Boolean output signal on a line  228 . In a first state the Boolean signal on the line  228  indicates that the ambient temperature is at or above a certain ambient temperature threshold value (e.g., 55° F.), and in a second state the signal indicates that the temperature is below the certain ambient temperature threshold value. The state of the signal on the line  228  is used in tests to determine if the ambient temperature is warm enough to allow the exothermic reactor to operate (e.g., see test  110  in  FIG. 4 ). 
   A photocell  22  ( FIG. 1 ) provides an input signal to comparator  230 , which also receives the voltage threshold value on the line  232 . The comparator  230  provides a Boolean output signal on a line  234  indicative of whether or not the amount of ambient light is above or below an ambient light threshold value. In a first state the Boolean signal on the line  234  indicates that the amount of ambient light is at or above the ambient light threshold value (e.g.,  20  foot-candles), and in a second state the signal indicates that the amount of ambient light is below the ambient light threshold value. The signals from comparators  210 ,  224  and  230  are input to the controller  54 . The controller also receives a reset signal from a manually controlled switch  240 . The signals from the comparators are checked by the controller  54  to perform the tests illustrated in  FIGS. 4–5 . 
   The controller  54  also receives a signal on a line  250  from a mode switch, which provides a signal to the controller  54  to advance the operating mode (e.g., on an edge transition). 
     FIG. 6  is a schematic illustration of an alternative embodiment controller  600 . This embodiment is substantially similar to the controller embodiment  200  illustrated in  FIG. 3 , with the principal exceptions of: (i) additional circuitry to detect an over heating of the catalyst temperature, and (ii) the circuit for driving the valve now includes a transistor rather than a silicon control rectifier (SCR) switch. Specifically, the amplified catalyst temperature signal on the line  62  is input to a comparator  602  that also receives a overheat threshold signal value on a line  604 . If the amplified catalyst temperature signal on the line  62  is greater than the overheat threshold signal value, the comparator  602  provides an output signal on a line  606 , that holds the system in reset, disabling the outputs (e.g., commanding the valve(s) to close to shut-off the flow of fuel). 
   In this embodiment, the controller  600  also includes a valve control logic circuit  614  responsive to the signal on the line  64  indicative of whether the catalyst temperature is above or below a certain threshold value. Dependent upon the value of the Boolean signal on the line  64 , capacitor  616  can be switched in parallel with the capacitor  618 . When the signal on the line  64  indicates that the catalyst temperature is below the certain threshold value, the valve control logic circuit  614  drives the valve open for a 25 millisecond duration every second. If the temperature is above the threshold, the valve control logic circuit  614  drives the valve(s) to open for 25 milliseconds every four seconds. 
     FIG. 7  is a schematic illustration of yet another alternative embodiment controller  700 . This embodiment is substantially the same as the embodiment illustrated in  FIG. 6 , with the principal exception that the logic for controlling the timing of the fuel valve opening and closing is implemented in the processor  54 , rather than as a separate logic circuit. Significantly, implementing the valve control logic within the processor provides flexibility in implementing various valve open and close timing as a function of the catalyst temperate. In addition, the driver circuits for driving the motor, the heater and the valve are now integrated into an integrated circuit  702 . 
   One of ordinary skill in the art will recognize that the present invention is of course not limited to the specific valve timing and threshold values discussed herein as way example. For example, the specific valve timing and threshold values will be a function of the overall system design. In addition, although the embodiments illustrated herein employ an ON/OFF valve, the system may be modified to use a modulating valve that receives a command signal to control the flow of gas from the tank, rather than opening and closing the valve. It is further contemplated that various types of sensors may be employed. For example, it is contemplated that sensors other than thermocouples, thermistors and photocells may be used to sense the associated parameters. Also, the present invention is not limited to placing the temperature sensor that senses the exhaust gas temperature in close proximity to the catalyst. Other locations in the CO 2  flow path may provide sensing locations that allow fuel flow to be controlled as a function of temperature, while maintaining the exothermic reaction. Furthermore, although the control technique of the present invention has been discussed in the context of closing the loop on temperature, it is contemplated that the loop may be controlled by sensing other parameter(s) indicative of the exothermic reaction (e.g., the amount of CO 2  gas). 
   It should be further understood that although the system employs a controller  54  ( FIG. 3 ) that receives Boolean inputs, a more complex controller may be used that, for example receives the sensed analog signal values, digitizes the values and processes the resultant digitized values to perform the control functions of the present invention. It suffices, that a number of different embodiments can be provided to enjoy the benefits of controlling the flow of fuel as a function of the exhaust gas/catalyst temperature. 
   Although the present invention has been shown and described with respect to several preferred embodiments thereof, various changes, omissions and additions to the form and detail thereof, may be made therein, without departing from the spirit and scope of the invention.