Abstract:
A vacuum electronic switch detection system allows multiple user selectable vacuum modes to be chosen with only one micro-controller input available for performing the multiple selectable modes. The switch detection system provides multiple voltage ratio control signals indicative of multiple switch position possibilities.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. patent application Ser. No. 11/870,929 filed on Oct. 11, 2007. The entire disclosure of the above application is incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure relates to vacuum electronics, and more particularly to an electronic switch detection system for a vacuum. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
     Conventional industrial shop vacuums are employed for both wet and dry usage. However, the electronics for conventional industrial shop vacuums can be primitive in design. 
     SUMMARY 
     The present disclosure provides electronics for an industrial shop vacuum that includes a vacuum electronic switch detection system to allow multiple user selectable vacuum modes to be chosen with only one micro-controller input available for performing the multiple vacuum selectable modes. The switch detection method provides multiple voltage ratio control signals indicative of multiple switch position possibilities. 
     Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
         FIG. 1  is a perspective of an industrial shop vacuum according to the principles of the present disclosure; 
         FIG. 2  is a schematic diagram of an industrial shop vacuum according to the principles of the present disclosure; 
         FIG. 3  is a schematic circuit diagram for the electronic controls according to the principles of the present disclosure; 
     
    
    
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. 
     With reference to  FIGS. 1 and 2 , an example vacuum  10 , according to the principles of the present disclosure, will now be described. The vacuum  10  may include a canister  12  and a vacuum head  14  that closes the canister  12 . The vacuum head may support a drive motor  16 . The drive motor  16  may support a suction fan  18 , which may be provided in a fan chamber  20  of the vacuum head  14 . The fan chamber  20  may be in fluid communication with an exhaust port  22  and an intake port  24 . The intake port  24  may be covered by a filter assembly  26  situated in a filter housing  28  of a vacuum head  14 . 
     A motor  16 , when powered up, may rotate the suction fan  18  to draw air into the suction inlet opening  30  and through the canister  12 , through the filter assembly  26 , through the intake port  24  and into the fan chamber  20 . The suction fan  18  may push the air in the fan chamber  20  through the exhaust port  22  and out of the vacuum  10 . A hose  32  can be attached to the inlet opening  30 . 
     The canister  12  can be supported by wheels  34 . The wheels  34  can include caster wheels, or the wheels can alternatively be supported by an axle. 
     A filter cleaning device  34  is provided including a filter cleaning motor  36  drivingly connected to a filter cleaning mechanism  38 . The filter cleaning mechanism  38  can take many forms, and can include an eccentrically driven arm  40  having fingers  42  engaging the filter  26 . The filter cleaning device  34  can be driven to traverse across the filter  26  to cause debris that is stuck to the filter to be loosened up and fall into the canister  12 . The arm  40  is connected to an eccentric drive member  44  which is connected to motor  36  and, when rotated, causes the arm  40  and fingers  42  to traverse across the surface of the filter  26 . 
     With reference to  FIG. 3 , a schematic diagram of the electronics  50  utilized to operate the vacuum  10  will now be described. The electronics  50  generally include a power cord  52  extending from the vacuum and adapted for connection with an AC power source  54 . In particular, the power cord  52  can include a plug  56  having a two-prong or three-prong connection as is known in the art, as is shown in  FIG. 2 . The power cord  52  is connected to a power source circuit  60 . An electrical isolation circuit  62  is provided in communication with the power source circuit  60  for providing a low voltage output VCC, as will be described in greater detail herein. A microcontroller  64  is provided in communication with the electrical isolation circuit  62  for receiving a low voltage supply VCC therefrom. The microcontroller  64  provides control signals to a filter cleaning circuit  66  and a vacuum circuit  68 . 
     A power tool sense circuit  70  is provided in communication with the microcontroller  64  for providing a signal to the microcontroller  64  regarding operation of a power tool that is plugged into an outlet  72  that can be disposed on the power tool  10 . The outlet  72  can be connected to the power cord  52  as indicated by nodes L, N. A water sense circuit  74  is provided in communication with the microcontroller for providing a signal (“water”) to the microcontroller  64  that the water level in the canister  12  has reached a predetermined level for deactivating the vacuum source in order to prevent water from being drawn into the vacuum filter  26 . 
     A multi position switch such as four position rotary switch  75  can be utilized for providing different activation states of a first micro-switch S 1  and a second micro-switch S 2  for controlling operation of the vacuum motor  16 . The switches S 1  and S 2  are connected to connectors A, B and A, C, respectively, wherein connectors B and C are connected to ratio circuits  76 ,  78 , respectively. Connector A provides an input signal to the microcontroller  64  indicative of the activation state of micro-switch S 1  and micro-switch S 2  in order to provide four modes of operation utilizing the two micro-switches S 1  and S 2  while providing just a single input into the microcontroller  64 . Table 1 provides a list of the mode selection possibilities of the four position user switch  75  with micro-switches S 1  and S 2  in the different activation states. 
     
       
         
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 User Switch 
                   
                   
                 Microcontroller 
               
               
                   
                 Position 
                 S1 
                 S2 
                 Input VCC Ratio 
               
               
                   
                   
               
             
             
               
                   
                 1 
                 0 
                 0 
                       0 * VCC 
               
               
                   
                 2 
                 0 
                 1 
                 (1/3) * VCC 
               
               
                   
                 3 
                 1 
                 0 
                 (4/5) * VCC 
               
               
                   
                 4 
                 1 
                 1 
                 (5/8) * VCC 
               
               
                   
                   
               
             
          
         
       
     
     With each of the four possible activation states of micro-switches S 1  and S 2 , the ratio circuit  76 ,  78  provide different ratio input signals as a function of the low voltage supply VCC. In particular, by way of example as shown in Table 1, when both switch S 1  and switch S 2  are open, a zero ratio VCC signal is received by the microcontroller  64 . When switch S 1  is open and switch S 2  is closed, a 1/3 ratio VCC signal is provided. When the switch S 1  is closed and switch S 2  is open, a 4/5 VCC ratio signal is provided, and when both switches S 1  and S 2  are closed, a 5/8 VCC ratio signal is provided to the microcontroller  64 . The ratios are determined by the resistance levels of resistors R 17 -R 20  provided in the ratio circuits  76 ,  78 . Ratios, number of switches, and number of resistors can vary for inputs other than 4. With these four input signals provided at a single microcontroller input, four user selectable modes are provided, thereby simplifying the microcontroller input and reducing the cost of the microcontroller. 
     The four user selectable modes can include position (1) vacuum off, power outlet is off, auto filter clean is off and filter clean push button is off; position (2) vacuum on, power outlet is off, auto filter clean is off and filter clean push button is on; position (3) vacuum on, power outlet off, auto filter clean is on and filter clean push button is on; and position (4) (auto mode) vacuum is controlled by outlet, auto filter clean is on and filter clean push button is on. These operation modes are exemplary and different modes can be enabled and disabled by the microcontroller  64 . Further, more or fewer switch positions can also be employed as well as more micro-switches and ratio circuits can also be utilized that are activated by the user switch for providing even further distinct operation modes. 
     A filter clean switch  80  is also provided for providing a signal to the microcontroller  64  for operating the filter cleaning device via activation of the filter cleaning circuit  66 . The filter cleaning circuit  66  includes an opto-coupler  82  which can be activated by a low voltage signal from the microcontroller  64 . The opto-coupler  82  provides an activation signal to a triac  84 . The triac  84  is an electronic switch similar to anti-parallel SCRs. When the gate of the triac  84  is held active, the triac  84  conducts electricity to the filter cleaning motor  36  for activating the filter cleaning device  34 . The opto-coupler  82  requires only a low power input for holding the triac  84  active. Additionally, the triac may be held continuously active for a time period then turned inactive, or pulsed active/inactive for a timer period, or the triac may be replaced by an SCR and driven with DC in a similar manner just described. The auto filter clean mode will turn off the vacuum for a brief period while the filter cleaning device  34  moves across the filter pleats. This can occur at predetermined intervals while the vacuum is operated continuously and every time the vacuum is turned off. The filter clean push button mode, when activated by user switch  75  and be pressing the push button  80 , will cause the vacuum to turn off for a brief period while the filter cleaning device  34  is operated to move across the filter pleats. 
     The microcontroller  64  can also provide a control signal to the vacuum circuit  68 . The vacuum circuit  68  is provided with an opto-coupler  86  which receives a low voltage signal from the micro-controller  64 . The opto-coupler  86  can provide an activation voltage to a triac  88  which is held active by the voltage supplied by the opto-coupler  86  to provide electricity to the vacuum motor  16 . The opto-coupler  86  requires only a low power input for holding the triac  88  active. 
     The power tool sense circuit  70  is provided with a current transformer  90  that senses current passing through an electrical connection to the power outlet  72  that supplies power to a power tool that can be plugged into the power outlet  72 . The current transformer  90  provides a signal to the microcontroller  64  indicative to the activation state of a power tool plugged into the outlet  72 . In response to the power tool sense circuit  70 , the microcontroller  64  can automatically activate the vacuum motor  16  for driving the vacuum source. Thus, when a power tool is plugged into the outlet  72  and is activated by a user, the vacuum motor  16  can be activated to assist in vacuuming debris that is created by the use of the power tool. The microcontroller  64  can delay deactivation of the vacuum motor  16  after the power tool is deactivated, to allow for the vacuum  10  to collect debris for a predetermined period of time after the power tool is deactivated. 
     The water sense circuit  74  includes a pair of water sense probes  96  disposed within the canister  12  of the vacuum  10 . Probes  96  can be connected to vacuum head  14  and can be suspended within the canister  12  below the level of the filter  26 . A buffer device  98  buffers the high impedance water sense input. The microcontroller on its own is unreliable in measuring the high impedance water sense input. The output of the buffer device or amplifier  98  goes to an analog input to the microcontroller  64 . The microcontroller software determines the analog level to detect water sense. The water sense probes  96  can be brass probes mounted in the vacuum&#39;s canister  12 . Water contacting between the probes will be detected by the water sense circuit  74  as a lower impedance. 
     The electrical isolation circuit  62  is provided to eliminate shock hazard. Three components provide isolation including the power supply transformer  100  as well as the current transformer  90  and the opto-couplers  82 ,  86 . The power supply transformer  100  provides a reduced voltage output from the power source  54 . By way of example, a five volt reduced power supply VCC can be provided by the electrical isolation circuit  62  from the AC line voltage source  54 . The circuit  60  previous to the transformer is the control circuit for the switching supply. The transformer provides isolation and is part of the switching supply. The five volt regulator takes the isolated control circuit output and reduces it to +5V regulated. 
     The low voltage power supply VCC is utilized by the microcontroller  64  for providing signals to the opto-couplers  82 ,  86  of the filter cleaning circuit  66  and vacuum circuit  68  as well as supplying power to the water sense circuit  74 . Furthermore, the ratio switch circuits  76 ,  78  are supplied with the low voltage VCC power supply.