Abstract:
An exhaust system for evacuation of vapor and gases from an area, the system including a fan mounted on a motor, an activation circuit coupled to the motor and adapted to couple the motor to a first voltage source, a detection circuit adapted to sense the presence of moisture on a sensor surface and to generate a detection signal when moisture is sensed and to not generate a detection signal when moisture is not sensed, and a control circuit. In one embodiment the control circuit is coupled to the detection circuit and the activation circuit and adapted to generate a control signal in response to the detection signal, the control signal received at the activation circuit to cause coupling of the motor to the first voltage source after a delay programmed in to a programmable logic chip in the control circuit.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present disclosed embodiments pertain to the evacuation of vapor or gas from an enclosed room and, more particularly, to the detection of moisture or water, particularly condensed water on a surface, and the control of an exhaust fan in response to the detection.  
         [0003]     2. Description of the Related Art  
         [0004]     The present disclosure provides a solution for preventing fungal and bacterial destruction of materials that are subject to moist environments. Current devices are both inadequate and non-functional with respect to providing protection from moisture and properly maintaining dry conditions. Considerable economic and physical loss may be experienced by both user and maintenance personnel either not switching on an exhaust fan or switching it on for such short times as to be ineffective as a means of preventing the accumulation of both fungal and bacterial outbreaks that are health threatening and destructive of the structures or stored objects themselves. This situation has long been and still is a large and growing economic and health issue.  
         [0005]     Hence, there is a need for automated control of exhaust systems used in bathrooms, shower rooms, kitchens, and other enclosed areas where moisture vapor, condensed moisture, and various gases must be exhausted. Numerous electro-mechanical solutions have been proposed. For example, in  The IC User&#39;s Casebook,  1988, Howard W. Sams, publisher, it shows at pp. 235-239 various generic circuits using contacts that trigger an output if liquid shorts the contacts. The liquid level detector shown in FIG. 16-7 of this reference fails to provide sufficient reliability in the environment to which the present disclosure is directed. This is due to the great need for sensitivity and reliability in sensing small amounts of moisture, which is neglected in these proposed designs. Moreover, the use of gold traces on sensor contacts was found to be useful only for corrosion control, and no recognition has been given to the use of gold to control circuit behavior.  
       BRIEF SUMMARY OF THE INVENTION  
       [0006]     The embodiments disclosed herein are directed to an exhaust system, including an electronic controller for a fan that is adapted to be used in environments in which moisture vapor, moisture in the form of condensation, and gases in various forms is undesirable. In accordance with one aspect of the disclosure, an exhaust system is provided that includes a fan mounted on a motor and in fluid communication with an exhaust duct; a detection circuit, a control circuit having a programmable circuit for receiving a detection signal from the detection circuit and generating an activation control signal in response thereto, and an activation circuit for coupling and uncoupling a current source to a fan motor in response to the control circuit.  
         [0007]     In accordance with another aspect of the disclosure, a low-voltage supply circuit provides a low voltage current for operation of at least one or more of the control circuit, the detection circuit, and the activation circuit without using a transformer.  
         [0008]     In accordance with another aspect of the disclosure, the system utilizes low-voltage components in the detector circuit, which includes a sensor and a conditioning circuit, and in the control circuit, which includes a programmable integrated circuit, as well as in the activation circuit, which generates a low voltage control signal to a relay that couples a high voltage line to the fan motor.  
         [0009]     In accordance with another aspect of the present disclosure, the sensor utilizes interlaced exposed gold lines on a printed circuit board in which each line has a width in the range of 0.4 to 0.6 mm and a preferred width of 0.5 mm, and the gap between the exposed gold lines is in the range of 0.2 mm to 0.4 mm in width with a preferred gap width of 0.3 mm.  
         [0010]     In accordance with another embodiment of the present disclosure, a controller for a fan is provided, the controller having a sensor adapted to detect the presence of condensed water and a circuit coupled to the sensor that is adapted to control operation of the fan in response to the sensing of condensed water by the sensor.  
         [0011]     In accordance with another aspect of the disclosure, a controller for an exhaust fan is provided that includes a sensor having electronic leads adapted to be bridged by condensed moisture to conduct current, and a circuit coupled to the sensor and adapted to control operation of the fan in response to the flow of current in the sensor.  
         [0012]     In accordance with another aspect of the present disclosure, the controller is fully automated in that it automatically activates the fan when condensed water is detected on the sensor and maintains activation of the fan for a set period of time. Alternatively, the controller can be adapted to permit manual deactivation of the fan or to permit both manual deactivation and automatic deactivation of the fan.  
         [0013]     In accordance with another aspect of the present disclosure, the sensor and the circuit are hardwired together and the circuit is coupled to the fan via either a hardwire or a wireless connection.  
         [0014]     In accordance with another aspect of the disclosure, the sensor is formed from exposed electrically-conductive leads that are designed to conduct current when the leads are bridged by condensed moisture.  
         [0015]     In accordance with another aspect of the present disclosure, the circuit is adapted to compare the amount of current conducted by the sensor with a reference current and to activate the fan when the conducted current by the sensor is at an appropriate level.  
         [0016]     In accordance with another aspect of the present disclosure, the controller utilizes an optical coupler to isolate high voltage or high current circuit components from low voltage components, such as sensing and switching components.  
         [0017]     In accordance with another aspect of the disclosure, an electronic circuit is provided for sensing moisture in any enclosed space (especially a bathroom with shower/tub) and by the use of appropriate signal conditioning, amplification, timing and on-site power switching causing the already installed exhaust fan to be switched on for a time appropriate to dry the affected space and then be automatically switched off. In the case of an average residential bathroom, this is about 20 min.  
         [0018]     In another embodiment of the present disclosure, miniature electronic components are provided to fit into the space provided for and replacing an ordinary and standard manual switch used to switch on a fan in a room or other chosen space. In accordance with one preferred embodiment, no additional wiring to the building&#39;s electrical system is required, and it is a direct replacement for the manual exhaust fan switch installed as standard practice in all toilet or shower facilities.  
         [0019]     In accordance with another aspect of the present disclosure, the controller automatically turns on the exhaust fan to air out or dry out the confined space in the event that a factory predetermined level of moisture or other substance or material has been exceeded, thereby limiting any destruction or health risks caused by negligence on the part of users or infrequent maintenance. Periodic maintenance schedules are often extended so far as to be ineffective in moisture control. In one embodiment, the controller of the present disclosure takes out of a user&#39;s control the option to turn off the exhaust fan but not the option to turn it on.  
         [0020]     In accordance with another embodiment of the disclosure, the controller is manufactured in such a way that all electronic components, sensor and pc board mounting fit into any ordinary switch box in a building electrical system and wire directly into the already installed wiring for the manual switch which it will replace. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0021]     The foregoing features and advantages of the present disclosure will be more readily appreciated as the same become better understood from the following detail description when taken in conjunction with the accompanying drawings, wherein:  
         [0022]      FIGS. 1A-1C  are a schematic of an exhaust fan controller formed in accordance with the present disclosure;  
         [0023]      FIGS. 2A and 2B  are illustrations of alternative applications for the exhaust fan controller formed in accordance with the present disclosure;  
         [0024]      FIGS. 3A and 3B  are an illustration of an alternative embodiment of an exhaust fan and accompanying controller formed in accordance with the present disclosure;  
         [0025]      FIG. 4  is a block diagram illustrating another embodiment of the present disclosure;  
         [0026]      FIG. 5  is a circuit schematic for circuits in the embodiment of  FIG. 4 ; and  
         [0027]      FIGS. 6A-6B  illustrate replacement of an existing fan switch with a controller of the present disclosure. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0028]     Referring to the embodiment of a vent fan controller shown in schematic form in  FIG. 1 , the components with reference labels SENS  1 , R 7 , R 1 , R 2  &amp; R 3 , Q 1 , and U 2  form the moisture sensing and post sensing conditioning circuit. The moisture sensor itself has in this case been chosen for its cost effect manufacture and low component requirements to reliably trigger the rest of the exhaust fan controller circuitry. In one embodiment, it has been made as a half inch by half inch PC board with gold leads arranged as two interleaved four pronged forks spaced at about 1/20 an inch between the tines. (Refer to  FIG. 1 , SENS 1  symbol details on the schematic).  
         [0029]     The NPN transistor(Q 1 ) receives a “moisture present” signal from the sensor and shapes it appropriately to be used to drive the LM311 Comparator (U 2 ), which, when the appropriate level is reached as determined by comparison to a reference current, will trigger the LS7213 Timer (U 5 ) to drive the output triac (U 4 ) for the appropriate time chosen, which is established by the values of R9 and C5. Nominal time is 20 min. Other values chosen for particular applications are adjustable from 1 second to hours. A signal from the Timer IC (U 5 ) pin  12  thru resister R 11  to D 2  will light the LED whenever the exhaust fan is on. The LED is optional but recommended.  
         [0030]     IC U 1  is a triac driver optical coupler used to isolate the 110V AC being switched on and off by the triac to the exhaust fan motor. This optoisolation decouples the triac 110V AC switching current from the low voltage supplied IC and transistors of the circuits.  
         [0031]     The low voltage power supply shown is known and certain versions are readily commercially available and will not be described in detail herein. In  FIG. 1  the miniature transformer (T 1 ), full wave bridge rectifier (D 1 ), electrolytic capacitor (C 1 ), and the IC 5 volt regulator (U 3 ) supply the necessary regulated 5 vdc to the entire circuit. Capacitors C 2 , C 3 , C 4 , and C 6  are bypass capacitors necessary to short unwanted voltage transients to ground.  
         [0032]     We have also found by experiment that the power supply can benefit from slight changes, substituting a 9V DC regulator to supply the entire circuit, with the exception of the LSI timer, which requires a 5V DC regulator. This makes a much more sensitive circuit, both in the lower level of moisture vapor it will detect and the speed of its response.  
         [0033]      FIG. 1  also shows the single 5V DC regulator option for the entire controller. While this makes it less sensitive to the amount of moisture vapor present, taking several minutes to switch on the exhaust fan motor, in most applications this delay is insignificant. In others the dual supply (9V DC and 5V DC) regulators are preferred as being more sensitive and timely.  
         [0034]     The light switch circuit shown at the bottom right of  FIG. 1  is another option for sites that may operate both the exhaust fan and the lights from the same manual switch. The miniature low voltage switches shown on the Schematic (SW 1  and SW 2 ) make the manual switching functions of turning on the fan motor at will, or turning the room lights on and off possible from a electrical box that formerly held only one manual electrical switch. Again, the optocoupler (U 6 ) isolates the AC being switched at the triac (U 7 ) from the low voltage portions of the circuits. The detailed parts list is shown below:  
                                             Vent Fan Controller            Description   Qty   Location               CAP 220 UF 25 V ELECT WT SMD   1   C1       CAP CERM. 1 UF 10% 25 V X7R 0603   2   C3, 4       CAP CER 2000 PF 50 V 5% C0G 0603   1   C5       FUSE 4 A 125 V SLO BLO NANO 2 SMF   1   F2       LED BLUE CLEAR 0805 SMD   1   D2       IC REG LDO MICROPOWER SOT23-5   1   U3       IC DIFF COMP STROBE 8-SOIC   1   U2       IC, LS7213-S, DELAY TIMER, 14-SOIC   1   U5       PHOTOCOUPLER TRIAC OUT 4-MSOP   1   U1       RECT BRIDGE SMD 100 V 1 A 4P DF-S   1   D1       RES 1.00K OHM ¼ W 1% 1206 SMD   1   R6       RES 100 OHM 1/10 W 1% 0603 SMD   1   R4       RES 100K OHM 1/10 W 1% 0603 SMD   2   R1, 3       SWITCH TACT SPST-NO 300GF G-WING   1   SW1       TRANS SS GP NPN 25 V LN SOT23   1   Q1       TRANSFORMER 9 V, 167 mA SECONDARY,   1   T1       115 V PRIMARY       TRIAC, 600 V 4 A, DPAK, SMD   1   U4       CAP CERAMIC .01 UF 100 V X7R 0603   1   C6       CAP CER 2.2 UF 10 V 10% X5R 0603   1   C2       RES 1.00K OHM 1/10 W 1% 0603 SMD   1   R11       RES 56.2K OHM 1/10 W 1% 0603 SMD   1   R9       RES 10K OHM 1/10 W 5% 0603 SMD   1   R5       RES 200 OHM 1/10 W 5% 0603 SMD   1   R7       RES 30K OHM 1/10 W 5% 0603 SMD   1   R2       PCB, VENT FAN CONTROLLER rev 04   1   0       CONN RECEPT 4POS 2 MM GOLD SMD   1   0       ASSEMBLY CHARGES FAN CONTROLLER   1   0       BOARD REV04                  
 
         [0035]    
       
         
               
             
               
               
               
             
           
               
                   
               
               
                   
               
               
                 Sensor Board 
               
             
          
           
               
                 Description 
                 Qty 
                 Location 
               
               
                   
               
               
                 PCB, SENSOR rev 01 
                 1 
                 0 
               
               
                 CONN HEADER 4POS 2 MM GOLD SMD 
                 1 
                 0 
               
               
                 ASSEMBLY CHARGES SENSOR BOARD REV01 
                 1 
                 0 
               
               
                   
               
             
          
         
       
     
         [0036]     The present disclosure provides an economical and practical means to detect and exhaust moisture vapor from indoor spaces. In checking patents published on the USPTO website, none were found to address or to be aimed at detecting and exhausting moisture automatically from indoor spaces, as this disclosure provides. There are proposed manually adjustable humidity sensors, requiring or allowing the user to determine if or when the exhaust fan motor will be switched on. The present disclosure is wholly dissimilar in several ways. First, the present disclosure is not based on sensing humidity, but the more direct moisture or condensation sensing. Second, the disclosure in one embodiment is truly automatic and does not allow users the option of turning the fan motor off, but only to turn it on. The third major difference is the adaptability of the various means the circuits offer to different room and electrical installations to accomplish condensation sensing and fan control.  
         [0037]     In the detail show in  FIG. 2A  the vent fan controller is configured to be installed as a direct replacement of an ordinary fan motor control switch. The configuration in  FIG. 2B  takes advantage of the flexibility allowed in new installations, as this allows the exhaust fan and the controller to be mounted on the ceiling of the subject room and permanently wired there before the room walls are installed.  
         [0038]      FIG. 3A  depicts a configuration that would mount on the ceiling of larger rooms, possibly in multiples, and using only the sensor, signal conditioning circuit, and a miniature radio frequency transmitter, would become the monitor of moisture events from the more ideal location on the ceiling. Upon triggering, this unit would send a radio frequency “moisture present” signal to a wall mounted receiver, timer, and triac controller, which would turn on the vent fan motor or motors in the case of multiple installations. The wall-mounted unit can also include a sensor.  
         [0039]     Each of these different adaptations of the basic design of the present disclosure are necessary in certain indoor situations; however, it should be noted that all of them could utilize either the small gold tined fork sensor of  FIG. 1  or the sensor found in any generic smoke detector interchangeably if each sensor is given its suitable signal conditioning circuit.  
         [0040]     Turning next to  FIG. 4 , shown therein is a block diagram of a exhaust fan controller circuit  50  formed in accordance with the present disclosure. The circuit  50  includes a detector circuit  52  coupled to a processor or control circuit  54 , which in turn is coupled to an activation circuit  56 . Not shown in this figure is a low voltage circuit that provides a low voltage, (e.g., 0.5, 1.0, 1.5, 3.0, or 5.0 volts) to these three circuits. While a transformer can be used to provide power from conventional house current, such has the disadvantages of inefficient use of energy, increased temperature at the circuit board, consumption of space, and increased costs to manufacture the circuit and hence the exhaust system. A more efficient source of low voltage is described herein below.  
         [0041]     The conditioning circuit  52  shown in  FIG. 4  includes a sensor  58  having an output  60  coupled to an input  62  of a transistor  64  in which the output  66  “Signal Out” is conditioned by the transistor  60  and a resistor  68 . The Signal Out is generated in response to the sensor  58  completing an open circuit between the interleaved leads  70 , such as with condensed moisture.  
         [0042]     Ideally, the leads  70  are deposited gold traces on a printed circuit board in which each trace is in the range of 0.4 to 0.6 mm in width, and having a preferred width of 0.5 mm, and the gap  72  between the exposed gold lines or traces  70  is in the range of 0.2 mm to 0.4 mm in width, with a preferred width of 0.3 mm. These size ranges and preferred dimensions in combination with the gold traces  70  provide a workable sensor circuit. While other materials can be used, they suffer from low resistance to corrosion, and they are not compatible with the trace width and gap width listed above due to conductivity properties. The use of gold traces  70  having the noted gaps  72  has been found to be reliable in moisture detection and exhaustion.  
         [0043]     However, the output signal of the detector  50  described above requires processing through the control circuit  54  in order to generate a reliable and usable control signal for the activation circuit  56 . More particularly, the control circuit  54  includes a memory  74  having software  76  stored therein, a user interface  78  for storing and modifying the software  76 , and a signal monitor  80  to receive as input the Signal Out from the detector circuit  52 .  
         [0044]     In one embodiment, the software  76  is in the form of BASIC or Assembly language code, such as the code shown below, that processes the output of the detector  52  to include a timing delay for the operation of the fan motor.  
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             list    p=10F200                #include &lt;p10F200.inc&gt;           _CONFIG _MCLRE_OFF &amp; _CP_OFF &amp;           _WDT_OFF                cblock   0x010                delayl                delaym           delayh                delayhh           delaylL                delaymL           delayhL                endc            ;************************************************************                ORG   0xFF           ORG   0x000           movwf   OSCCAL           GOTO    start            ; ——————————————————————————————————————                  ;INITIALIZE MICROCONTROLLER                SETUP   movlw b‘00000111’                option                movlw   B‘00001001’                tris   GPIO           clrf   GPIO           retlw    0x000            ; - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -                start call SETUP           MAIN CLRF GPIO                BTFSS   GPIO,3           GOTO   FANON           BTFSS   GPIO,0           GOTO   FANON           GOTO   MAIN            ; ——————————————————————————————————————                  FANON                HO   BSF    GPIO,2                BTFSS    GPIO,0           GOTO   HO           BSF   GPIO,2           BSF   GPIO,1           CALL   DELAY           GOTO    FANOFF           GOTO    MAIN            ; - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -                FANOFF                A    BTFSS   GPIO,0                GOTO    A           BCF   GPIO,2           BCF   GPIO,1           GOTO    MAIN            ; - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -                DELAY                clrf   delayl                CLRF delaym           movlw.000           movwfdelayh                movlw   .14           movwf   delayhh                wait                decfsz   delayl,f                goto wait                BTFSS   GPIO,0           GOTO   FANOFF                decfszdelaym,f                goto wait           decfszdelayh,f           goto wait                decfsz   delayhh,f                goto wait                RETLW 0X000            ; - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -                GOTO MAIN                END                      
 
         [0045]     The control circuit  54  can utilize a low voltage programmable integrated chip, such as the MIC 10F200T-I/OT, which is readily commercially available and will not be described in further detail herein. Included in the control circuit  54  is a on-reset switch  82  that enables a user to turn the fan on or to reset the timing of the operation of the fan motor. The low-voltage/low current output  84  of the control circuit  54  carries the control signal to the activation circuit  56 , which includes a relay  86  coupled to conventional house current/voltage as described above. Energizing of the relay  86  with the control signal closes the contacts  88 . In the illustrated embodiment of  FIG. 4 , the contacts  88  are shown in a position in which the fan motor is not energized.  
         [0046]     Preferably, the delay time is 20 minutes, meaning the circuit energizes the fan for 20 minutes. the fan can be turned off via the manual switch, but the sensor can override the manual switch if moisture is detected or is still present on the sensor.  
         [0047]     This is shown more clearly in the detailed circuit schematic of  FIG. 5  in which like components are identified with the same reference numbers. Additional components are also shown, and these are identified on the parts list below:  
                                                   PARTS LIST TO SCH REV.9.B   BBI           Description   Location                           CAP CER 4.7 uF 10 V Y5V 0603   C1           CAP CER.01 uF 100 V X7R 0603   C2           CAP 470 uF 25 V ELECT VZ RADIAL   C3           CAP 1.5 uF 305VAC EMI SUPPRESSION   C4           DIODE ZENER 5 W 6.8 V DO41   D1           IC RECT BRIDGE 0.5 A 200 V MBS-1   D2           DIODE SMD STANDARD BLOCKING   D3           LED BLUE CLEAR 0805 SMD   D4           FUSE FAST-ACT 10. A 250 V UL TR5   F1           DIODE TVS 150 V 600 W BIDIR 5% SMB   D5           TRANS SS GP NPN 25 V LN SOT23   Q1           TRANS SS GP NPN 25 V LN SOT23   Q2           RELAY PCB HI-CAPACITY 10 A 5VDC   RLY1           RES 1.0 M OHM ¼ W 5% 1206 SMD   R1           RES 47 OHM ½ W 5% 2010 SMD   R2           RES 1K OHM 1/10 W 1% 0603   R3           RES 1M OHM 1/10 W 1% 0603   R4           RES 1K OHM 1/10 W 1% 0603   R5           RES 1K OHM 1/10 W 1% 0603   R6           SWITCH-TACT SPST-NO MOM SMT J TYPE   S1           IC REG LDO MICROPOWER SOT23-5   U1           IC PIC PROCESSOR 10F200T-I/OT   U2           PCB CIRCUIT TO MOUNT PARTS   PCB1           PCB SENSOR IMMERSION GOLD   PCB2           BLACK 18AWG STRANDED 105deg C.   W1           WHITE 18AWG STRANDED 105deg C.   W2           BLUE 18AWG STRANDED 105deg C.   W3           WIRE 26AWG STRANDED 50 mm   W4           WIRE 26AWG STRANDED 50 mm   W5                      
 
         [0048]     Improvements in this embodiment include additional tines in the sensor. The tines are wider and spaced closer together. In one embodiment, the tines are formed of copper that is coated with gold material, 24 ct. gold using standard PCB emersion coating. It was found that these changes make the sensor very sensitive to dew point, and it provides a heretofore unexpected improvement over existing similar sensors.  
         [0049]     In a wall-mount version the sensor is readily accessible through a window formed in the housing for inspection and cleaning. The sensor can easily be cleaned because of the gold deposition on a fiberglass PCB, and it is corrosion resistant because it is not made of a porous material that absorbs moisture. The non-porous material of the present embodiment is easily cleaned and maintained by wiping the sensor face with a mild degreaser, such as household window cleaner. The sensor can be manufactured at most PCB manufacturers, resulting in a lower cost to produce.  
         [0050]     The reaction time has been improved by using the PIC processor, which controls the reaction time, deletes parts, and results in a simpler controller that is more reliable and less costly to manufacture.  
         [0051]     The controller is no longer powered by a transformer, which is replaced by a transformerless circuit that saves energy, drops temperature to the circuit board, gives the PCB more room for future add-ons, and it is also less costly to manufacture.  
         [0052]     The signal conditioning circuit has utility with sensors other than those that sense moisture, making for a much approved approach to other types of sensors.  
         [0053]      FIGS. 6A-6B  illustrate the steps of replacing a conventional fan wall switch  90  with the controller  92  of the present disclosure.  FIG. 6A  shows the existing switch  90  removed from the wall box after power to the switch  90  has been shut off. Once the wires  94 ,  96  are removed from the existing switch  90 , the new controller  92  is hooked up as shown, i.e., blue controller wire to the existing black wire, the white controller wire to the existing white wire, and the black controller wire to the remaining wire in the wall box.