Patent Abstract:
A wood floor edger is disclosed herein. An embodiment of the edger comprises a housing and a motor. The housing comprises an opening and a rotatable abrasive disc located in the opening. The rotatable abrasive disc may have a diameter greater than six inches. The motor is operatively connected to the first housing and drivingly connected to the abrasive disc. A motor controller is electrically connected to the motor, wherein the motor is operatable at a speed that is preselected by the motor controller.

Full Description:
REFERENCE TO CO-PENDING PROVISIONAL APPLICATION 
     The benefit of earlier-filed co-pending U.S. Provisional Patent Application Serial No. 60/402,361 filed Aug. 8, 2002 for WOOD FLOOR EDGER, which is hereby incorporated by reference for all that it discloses, is hereby claimed. 
    
    
     BACKGROUND 
     Floor edgers, sometimes referred to herein simply as edgers, are used to sand or polish floors in the proximity of vertical structures such as walls and base boards. Edgers operate by rotating an abrasive disc that contacts the floor, wherein the rotating abrasive disc polishes or sands the floor. The abrasive disc typically spins at a high speed, such as 3,200 rpm. 
     Conventional edgers use brush-type electric motors to spin the abrasive disc. The brush-type motors typically operate at a preselected speed or speeds for a given load. The motors may spin faster than the abrasive disc and a reduction device, such as gears, may be located between the motor and the abrasive disc. For example, a brush-type motor may operate at a speed of 10,000 rpm when no load is applied to the abrasive disc, such as when the abrasive disc is not contacting the floor. However, when the abrasive disc experiences a load, such as contacting a floor, the speed of the motor and, thus, the abrasive disc, typically slows down. Depending on the power of the motor, this slow down may be significant enough to reduce the effectiveness of the edger. 
     In addition to slowing down the speed of the abrasive disc, the loaded condition of the brush-type motor also may cause the motor to draw more current than it draws at a no-load condition. This additional current draw may cause circuits connected to the edger to exceed limits, which may cause circuit breakers to disconnect the circuits and cut power to the edger. Furthermore, the additional current draw may also present safety issues, such as overheating of the edger and the aforementioned circuits connected to the edger. 
     Another problem with brush-type motors used in edgers is that they are heavy, which causes the edgers to be heavy. Because edgers operate close to the floor, heavy edgers are difficult to maneuver. The heavy edgers may also cause excessive strain on the users of the edgers because the users typically have to bend over or kneel in order to operate the edgers. 
     SUMMARY 
     A wood floor edger is disclosed herein. An embodiment of the edger comprises a housing and a motor. The housing comprises an opening and a rotatable abrasive disc located in the opening. The rotatable abrasive disc may have a diameter greater than six inches. The motor is operatively connected to the first housing and drivingly connected to the abrasive disc. A motor controller is electrically connected to the motor, wherein the motor is operatable at a speed that is preselected by the motor controller. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side perspective view of an embodiment of an edger. 
         FIG. 2  is schematic diagram providing an embodiment of the electronic in the edger of  FIG. 1 . 
         FIG. 3  is a perspective view of an embodiment of the motor of  FIG. 1 . 
         FIG. 4  is a side cut-away view of the motor of  FIG. 3 . 
         FIG. 5  is a side view of an embodiment of the first housing of the edger of  FIG. 1  including some of the components located in the housing. 
     
    
    
     DETAILED DESCRIPTION 
     An exemplary embodiment of an edger  100  is shown in  FIG. 1 . As described in greater detail below, the edger  100  may be used to sand a wood floor adjacent a vertical structure, such as a wall or a baseboard. The edger  100  of  FIG. 1  includes a lower housing  104  (sometimes referred to as a first housing or a base), an upper housing  106  (sometimes referred to as a second housing), and a motor  110  or motor housing located therebetween. The upper housing  106  may have a handle  114  attached thereto. In addition, a switch  116 , a speed control  117 , and a power cord  118  may be attached to the upper housing. The upper housing  106  may contain electronics that serve to operate the motor  110  as described in greater detail below. 
     The handle  114  is adapted to be grasped by a user of the edger  100  in order to control the motion of the edger  100 . For example, the handle  114  enables a user to carry the edger  100  and to maneuver the edger  100  against a wall or baseboard that abuts a floor. The power cord  118  serves to provide electric power to the edger  100  and the switch  116  serves to turn the motor off and on. As described in greater detail, the electronics in the upper housing  106  may only enable the motor  110  to run if the switch  116  is toggled. Thus, the motor  110  cannot start if power is applied to the power cord  118 . Rather, the switch  116  must be toggled in order for the motor  110  to operate. The speed control  117  may function in conjunction with the electronics and serves to control the rate of rotation of the motor  110  and, thus, the abrasive disc. The electronics associated with the edger  100  are described in greater detail below. It should be noted that the electronics have been described as being located in the upper housing  106 , however, the electronics may be located in other portions of the edger  100 . 
     The lower housing  104  has a front portion  120 , a rear portion  121 , an upper portion  122 , and a frame  124  attached thereto. The front portion  120  is adapted to contact a floor that is being sanded or polished. The front portion  120  is also adapted to contact an vertical edge, such as a baseboard or wall, that is located adjacent the floor. The rear portion  121  may be adapted to be located slightly above the floor, which may provide air flow for the removal of dust generated during the sanding process as described in greater detail below. In one embodiment, the lower housing  104  includes a fan (not shown) that is operatively connected to the motor  110  by way of a belt. The fan serves to provide air flow for the removal of dust. The use of a belt reduces maintenance costs associated with the edger and is typically more efficient that a gear driven fan. The upper portion  122  is adapted to receive the motor  110 . For example, the shape of the upper portion  122  may match the shape of the motor  110 . 
     The frame  124  serves to support wheels  126 , such as caster-type wheels, that are attached to the frame  124 . The wheels  126  serve to enable movement of the edger  100  and to maintain the rear portion  121  of the lower housing  104  a preselected distance from the floor. The front portion  120  of the lower housing  104  contacts the floor and, therefore, is not able to move as freely as the rear portion  121 . This reduced motion serves to keep the abrasive disc (not shown), which is located in the front portion  120  of the lower housing  104 , at a selected location on the floor. 
     An embodiment of the wheels  126  includes a threaded shaft  127  that is treaded into the frame  124 . A lock nut  128  is threaded onto the shaft  127  in order to prevent the shaft  127  from rotating unless the lock nut  128  is loosened. In order to adjust the height of the rear portion  121  of the lower housing  104 , the lock nut  128  is loosened. The shaft  127  is then rotated until a desired height of the rear portion  121  is achieved. The lock nut  128  is then tightened in order to prevent the shaft  127  from moving, which maintains the rear portion  121  at the desired height. 
     A port  130  may be located in the proximity of the rear portion  121 . A vacuum device may be connectable to the port  130 . For example, a vacuum hose may be connected to the port  130  and may serve to collect dust generated by the edger  100 . Airflow passes under the rear portion  121  of the lower housing  104  and through the port  130  to the vacuum device. The above-described fan enhances the air flow so as to enhance dust removal. 
     A more detailed embodiment of the lower housing  104  is shown in  FIG. 5 . The lower housing  104  includes a fan  250  that may be attached by hardware to the shaft  170 ,  FIG. 3 , of the motor  110 . A plate  254  may be mounted below the fan. The plate  254  may form a compartment in which the fan  250  is located and may serve to protect the fan  250  and divert air from the opening in the lower housing  104  through the port  130 . A belt  260  may also be operatively connected to the shaft  170 ,  FIG. 3 . The belt  260  may also be connected to a pulley  262 . The pulley  262  may be connected to hardware  264 , such as coupling hardware, which may be connected to a shaft  266 . The shaft  266  may be connected to a plate  270 , which in turn is connected to rotatable sanding discs  272  and  274 . Thus, the motor  110 ,  FIG. 3 , serves to rotate both the fan  250  and the rotatable discs  272 ,  274 , which are located in the lower housing  104 . 
     Examples of the motor  110  include a brushless motor and a permanent magnet motor. Both of these examples of motors serve to reduce the weight of the edger  100  relative to edgers having conventional brush-type motors. For example, the edger  100  may weigh less than twenty-eight pounds. One embodiment of the edger  100  weighs about twenty-seven pounds. The brushless motor also requires less current than a brush motor when operating at the same speed or providing the same horsepower as a brush-type motor. In one embodiment, the motor  110  provides approximately 2.4 horsepower. 
     Having described the components of an embodiment of the edger  100 , the various components of the edger  100  will now be described in greater detail. 
     The upper housing  106  may include electronic devices and the like that serve to operate the motor  110 . The electronic devices may include a motor controller  160  as shown in  FIG. 2 . The motor controller  160  serves to supply power to the motor and to regulate the operation of the motor  110 . As described above, the motor  110  may, as an example, be a brushless motor. Accordingly, the electronic devices may supply direct current power to the brushless motor. 
     The use of brushless motor has many benefits over a brush-type motor. For example, a brushless motor provides greater power over a brush-type motor. In addition, the brushless motor  110  does not have brushes that may wear or become contaminated as with a brush-type motor. A brushless motor maintains a more constant speed under loaded conditions than a brush-type motor. Examples of brushless motors are provided in the following U.S. patents, which are all hereby incorporated by reference for all that is disclosed therein: U.S. Pat. Nos. 6,414,408; 6,407,466; 6,396,225; 6,388,405; 6,385,395; 6,380,707; 6,379,126; 6,377,008; 6,420,805; 4,922,169; and 4,641,066. 
     One non-limiting embodiment of a motor  110  operates at approximately 10,500 revolutions per minute (rpm) at approximately 2.2 horsepower. The motor  110  may draw approximately three amperes under no load conditions. The motor  110  may draw approximately seven to eight amperes under normal load conditions and approximately twelve amperes under heavy load conditions. Therefore, the edger  100  may operate from a conventional one-hundred ten volt, fifteen ampere outlet. Under these conditions, the abrasive disc operates at approximately three-thousand two-hundred rpm. The power may be supplied to the motor  110  by a direct current (DC) power supply located in the upper housing  106  that generates approximately one-hundred sixty volts DC. 
     An embodiment of the motor  110  is shown in  FIG. 3 . The motor  110  may have a housing  164  with an end bell  166  attached thereto. The housing  164  may be substantially closed, so as to prevent contaminants from interfering with the operation of the motor  110 . The end bell  166  may serve to secure the housing  164  to other portions of the edger  100 ,  FIG. 1 . For example, the end bell  166  may attach to the upper portion  122 ,  FIG. 1 , of the lower housing  104 . The motor  110  may have an end  168  located opposite the end bell  166  to which other components of the edger  100 ,  FIG. 1 , may be attached. For example, the upper housing  106 ,  FIG. 1 , may be attached to the end  168 . A shaft  170  may extend from the housing  164  and through the end bell  166 . The shaft  170  may be operatively attached to a abrasive disc or the like (not shown) that are located in the lower housing  104 . The shaft  170  may also be connected to or at least operatively connected to the above-described fan (not shown). 
     A circuit  174  may be located proximate the end  168  and may serve to monitor the operation of the motor  110 . The circuit  174  may have contacts or other connections that serve to electrically connect the circuit  174  to other components within the motor controller  160 ,  FIG. 2 , as described in greater detail below. For example, the circuit  174  may monitor the speed of the shaft  170  in addition to the amount of current being drawn by the motor  110 . In one embodiment, electric power supplied to the motor  110  is supplied via the circuit  174 . 
     A side-cut away view of an embodiment of the motor  110  is shown in  FIG. 4 . The motor  110  depicted in  FIG. 4  is a brushless motor. The motor  110  may have a first fan  178  and a second fan  180  connected to the shaft  170  and located within the housing  164 . The fans  178  and  180  serve to cool the motor  110 . The use of two fans serves to improve the cooling capability significantly over an embodiment using no fans or a single fan. 
     At least one magnet  182  is attached to the shaft  170 . At least one field winding  184  is attached to the housing  164  in the proximity of the magnet  182 . The current flow through the field winding  184  is controlled by the motor controller  160 ,  FIG. 2 , and serves to control the speed of the shaft  170 . For example, the motor controller  160  may monitor the speed of the shaft  170  via the circuit  174  and adjust the current to the field winding  184  so as to maintain the speed of the shaft  170  regardless of the load experienced by the motor  110 . 
     Having described the motor  110 , the other components of the motor controller  160  will now be described. 
     Referring again to  FIG. 2 , the motor controller  160  may have an input  180  that may be connected to a conventional alternating current (AC) voltage source. One such source may provide approximately one-hundred ten volts at approximately twelve amperes when the motor  110  is operating under its maximum load. Accordingly, the edger  100 ,  FIG. 1 , is able to operate on most standard one-hundred ten volt circuits without causing circuit breakers to trip. 
     The input  185  is electrically connected to a switch  186 , which may be operatively connected to the switch  116  if  FIG. 1 . Depending on the state of the switch  186 , the input  185  is either connected to a logic circuit  187  or a DC converter  188 . In summary, the logic circuit  187  detects the state or transition of the switch  186  prior to instructing other components within the motor controller  160  to operate. This prevents the motor  110  from operating unless the switch  186  is toggled. For example, the logic circuit  187  may detect the voltage provided by the input  185 . In the embodiment described herein, the voltage at the DC converter  188  is required to transition from a low voltage to a high voltage in order for the other components within the motor driver  160  to operate. This transition assures that the motor  110  will only operate when the switch  186  has transitioned from an off position to an on position. Thus, the motor  110  will not start if power is supplied at the input  185  when the switch  186  is in the on position. It should be noted that the switch  186  as shown in  FIG. 2  is in an off position. 
     One embodiment of the logic circuit  187  detects the voltage supplied at the input  185  by way of a contact  188  within the switch  186 . The voltage level at the contact  188  will be high when power is supplied to the input  185  and the switch is in the off position. When the switch  186  is toggled to the on position, the voltage level at the contact  188  will transition to a low voltage. Upon the transition from the high voltage level to the low voltage level, the logic circuit  187  may output a signal or instruction that enables other components within the motor controller  160 , including the motor  110 , to operate. 
     If the switch  186  is in the on position when power is supplied to the input  185 , the voltage level at the contact  188  will be low. Accordingly, the voltage level at the contact  188  will not transition from a high voltage to a low voltage. The lack of such a transition will prevent the logic circuit  187  from enabling other components in the motor driver  160  to operate. Accordingly, the motor  110  will not operate. However, operation of the motor controller  160  may be enabled by toggling the switch  186  to the off position and then to the on position. This toggling will generate the high to low voltage level on the contact  188  that is required in order for the logic circuit  187  to enable the operation of the motor controller  160 . 
     The DC converter  188  converts AC power supplied at the input  185  of the motor controller  160  to DC power for use by the motor  110  and other components in the motor controller  160 . The DC converter  188  may have an output  190  which serves as an output for the DC power. The DC voltage may, as an example be, approximately one-hundred sixty volts and the current may be up to twelve amperes depending on the load on the motor  110 . 
     The DC power supplied by the DC converter  188  is supplied to an input  192  of a low voltage power supply  194  and an input  198  of a phase drivers circuit  200 . It should be noted that DC power may be supplied to other components (not shown) within the motor controller  160 . As described in greater detail below, the phase drivers circuit  200  in conjunction with commutation logic  204  serves to supply electric power to the motor  110 . 
     The low voltage power supply  194  converts the DC voltage supplied by the DC converter  188  to a level more appropriate for low voltage components within the motor controller  160 . In the embodiment described herein, the low voltage power supply  194  has an output  206  that is electrically connected to the commutation logic  204  and microprocessor logic  210 . The low voltage power supply  194  may, as an example, be a switching power supply and may supply five volts DC. 
     The microprocessor logic  210  serves to control the operation of the motor  110 . For example, the microprocessor logic  210  may ultimately control the speed of the shaft  170 , including providing a slow start up speed. The microprocessor logic  210  may also cause power to be removed from the motor  110  in the event that the shaft  170  is unable to rotate. For example, if the shaft  170  or the abrasive disc (not shown) become jammed, the microprocessor logic  210  may cause power to be disconnected from the motor  110 . 
     The microprocessor logic  210  may have a first input  212  that is electrically connected to the logic circuit  187 . In one embodiment, the microprocessor logic  210  may have a second input  214  that is electrically connected to the commutation logic  204  as described in greater detail below. An output  220  of the microprocessor logic  210  may be electrically connected to an input  222  of a speed regulator  226 . It should be noted that the output  220  of the speed regulator  226  and the input  222  of the speed regulator  226  may, in some embodiments provide two-way communications between the microprocessor logic  210  and the speed regulator  226 . 
     The speed regulator  226  in combination with the speed control  117  provides for a user to set the speed at which the shaft  170  and, thus, the abrasive disc, spins. The speed regulator  226  may have an output  228  that outputs signals or data to an input  230  of the commutation logic  204 . As described in greater detail below, the user may adjust the speed control  117  in order to set the speed of the shaft  170 . As also described in greater detail below, the speed of the shaft  170  remains substantially constant as the physical load on the shaft  170  varies. Feedback within the motor controller  160  monitors the speed of the shaft  170  and compares it to the speed set by the speed regulator  226 . The motor controller  160  then adjusts the speed of the shaft  170  so that it corresponds to the speed established by the speed regulator  226 . 
     The commutation logic  204  monitors the data and other signals generated by the circuit  174  and generates data or other signals to control the speed of the shaft  170 . The input  230  of the commutation logic  204  is connected to the output  228  of the speed regulator  226  and an output  232  is connected to the second input  214  of the microprocessor logic  210 . The commutation logic  204  also has multiple inputs  234  from the motor  110  and multiple outputs  236  connected to the phase drivers circuit  200 . The inputs  234  may be electrically connected to the circuit  174  and may carry data regarding the performance of the motor  170 . The outputs  236  carry data indicating the current that is to be supplied to the motor  110  by the phase drivers  200  as described in greater detail below. 
     The phase drivers  200  has multiple inputs  240  connected to the multiple outputs  236  of the commutation logic  204 . The phase drivers  200  also have multiple outputs  242  connected to the motor  170 . The phase drivers  200  supply electric power to the motor  110  depending on signals or voltage levels at the multiple inputs  240 . The power is supplied to the motor  110  via the multiple outputs  242 . Therefore, low power supplied by at the multiple inputs  240  can regulate high power output at the multiple outputs  242 . 
     Having described the components of the motor controller  160 , its operation will now be described. 
     As described above, the logic circuit  187  determines whether the motor  110  may rotate depending on the state of the switch  186 . If the logic circuit  187  determines that the motor  110  may rotate, a signal is provided to the microprocessor logic  210  to active the motor  110 . The microprocessor logic  210  senses that the motor  110  is being started from a stopped position and outputs a signal via the output  220  to the speed regulator  226 , which causes the speed of the motor  110  to start slow and increase to a speed established by the setting of the speed control  117 . The slow start of the motor  110  serves to attenuate power surges on the components of the motor controller  160 . In addition, the slow start of the motor  110  reduces the initial torque on the edger  100 , which lessens the possibility that a user will suddenly lose control of the edger  100  during start up. 
     The speed information regarding the speed at which the motor  110  is to operate is transmitted to the commutation logic  204  by way of the output  228 . For example the speed information may correspond to a voltage or a binary number output at the output  228  of the speed regulator  226 . Thus, during start up, the output  220  of the microprocessor logic  210  causes the speed regulator  226  to output a slow speed instruction to the commutation logic  204 . The speed may increase as a ramp function until the speed established by the speed control  117  is achieved. 
     The commutation logic  204  outputs voltages or other signals on the outputs  236 , which causes the phase drivers  200  to output voltages on the outputs  242 . These voltages or signals correspond to the speed and/or power requirements of the motor  110 . The inputs  234  to the commutation logic  200  receive information regarding the status of the shaft  170  and the motor  110 . For example, the shaft speed and amount of current drawn by the motor  110  may be output to the commutation logic  204 , which may transmit this data to the microprocessor logic  210 . Therefore, the microprocessor logic  210  may monitor the motor, including the speed of the shaft  170  as it encounters various loads and may cause the commutation logic  204  to increase or decrease the voltage output by the outputs  242  accordingly. Therefore, the speed of the shaft  170  is maintained relatively constant under varying loads. 
     Should the commutation logic  204  detect that the shaft  170  is stationary and that high current is being supplied to the motor  110 , the commutation logic  204  may disable the phase drivers  200 . This disabling is due to the detection of the shaft  170  being jammed or overloaded. Accordingly, the motor  110  will shut down. If the motor  110  were to continue to receive electric power, it could overheat or cause other components in the motor controller  160  to overheat.

Technology Classification (CPC): 1