Floor edger

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.

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.

DETAILED DESCRIPTION

An exemplary embodiment of an edger100is shown inFIG. 1. As described in greater detail below, the edger100may be used to sand a wood floor adjacent a vertical structure, such as a wall or a baseboard. The edger100ofFIG. 1includes a lower housing104(sometimes referred to as a first housing or a base), an upper housing106(sometimes referred to as a second housing), and a motor110or motor housing located therebetween. The upper housing106may have a handle114attached thereto. In addition, a switch116, a speed control117, and a power cord118may be attached to the upper housing. The upper housing106may contain electronics that serve to operate the motor110as described in greater detail below.

The handle114is adapted to be grasped by a user of the edger100in order to control the motion of the edger100. For example, the handle114enables a user to carry the edger100and to maneuver the edger100against a wall or baseboard that abuts a floor. The power cord118serves to provide electric power to the edger100and the switch116serves to turn the motor off and on. As described in greater detail, the electronics in the upper housing106may only enable the motor110to run if the switch116is toggled. Thus, the motor110cannot start if power is applied to the power cord118. Rather, the switch116must be toggled in order for the motor110to operate. The speed control117may function in conjunction with the electronics and serves to control the rate of rotation of the motor110and, thus, the abrasive disc. The electronics associated with the edger100are described in greater detail below. It should be noted that the electronics have been described as being located in the upper housing106, however, the electronics may be located in other portions of the edger100.

The lower housing104has a front portion120, a rear portion121, an upper portion122, and a frame124attached thereto. The front portion120is adapted to contact a floor that is being sanded or polished. The front portion120is also adapted to contact an vertical edge, such as a baseboard or wall, that is located adjacent the floor. The rear portion121may 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 housing104includes a fan (not shown) that is operatively connected to the motor110by 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 portion122is adapted to receive the motor110. For example, the shape of the upper portion122may match the shape of the motor110.

The frame124serves to support wheels126, such as caster-type wheels, that are attached to the frame124. The wheels126serve to enable movement of the edger100and to maintain the rear portion121of the lower housing104a preselected distance from the floor. The front portion120of the lower housing104contacts the floor and, therefore, is not able to move as freely as the rear portion121. This reduced motion serves to keep the abrasive disc (not shown), which is located in the front portion120of the lower housing104, at a selected location on the floor.

An embodiment of the wheels126includes a threaded shaft127that is treaded into the frame124. A lock nut128is threaded onto the shaft127in order to prevent the shaft127from rotating unless the lock nut128is loosened. In order to adjust the height of the rear portion121of the lower housing104, the lock nut128is loosened. The shaft127is then rotated until a desired height of the rear portion121is achieved. The lock nut128is then tightened in order to prevent the shaft127from moving, which maintains the rear portion121at the desired height.

A port130may be located in the proximity of the rear portion121. A vacuum device may be connectable to the port130. For example, a vacuum hose may be connected to the port130and may serve to collect dust generated by the edger100. Airflow passes under the rear portion121of the lower housing104and through the port130to the vacuum device. The above-described fan enhances the air flow so as to enhance dust removal.

A more detailed embodiment of the lower housing104is shown inFIG. 5. The lower housing104includes a fan250that may be attached by hardware to the shaft170,FIG. 3, of the motor110. A plate254may be mounted below the fan. The plate254may form a compartment in which the fan250is located and may serve to protect the fan250and divert air from the opening in the lower housing104through the port130. A belt260may also be operatively connected to the shaft170,FIG. 3. The belt260may also be connected to a pulley262. The pulley262may be connected to hardware264, such as coupling hardware, which may be connected to a shaft266. The shaft266may be connected to a plate270, which in turn is connected to rotatable sanding discs272and274. Thus, the motor110,FIG. 3, serves to rotate both the fan250and the rotatable discs272,274, which are located in the lower housing104.

Examples of the motor110include a brushless motor and a permanent magnet motor. Both of these examples of motors serve to reduce the weight of the edger100relative to edgers having conventional brush-type motors. For example, the edger100may weigh less than twenty-eight pounds. One embodiment of the edger100weighs 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 motor110provides approximately 2.4 horsepower.

Having described the components of an embodiment of the edger100, the various components of the edger100will now be described in greater detail.

The upper housing106may include electronic devices and the like that serve to operate the motor110. The electronic devices may include a motor controller160as shown inFIG. 2. The motor controller160serves to supply power to the motor and to regulate the operation of the motor110. As described above, the motor110may, 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 motor110does 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 motor110operates at approximately 10,500 revolutions per minute (rpm) at approximately 2.2 horsepower. The motor110may draw approximately three amperes under no load conditions. The motor110may draw approximately seven to eight amperes under normal load conditions and approximately twelve amperes under heavy load conditions. Therefore, the edger100may 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 motor110by a direct current (DC) power supply located in the upper housing106that generates approximately one-hundred sixty volts DC.

An embodiment of the motor110is shown inFIG. 3. The motor110may have a housing164with an end bell166attached thereto. The housing164may be substantially closed, so as to prevent contaminants from interfering with the operation of the motor110. The end bell166may serve to secure the housing164to other portions of the edger100,FIG. 1. For example, the end bell166may attach to the upper portion122,FIG. 1, of the lower housing104. The motor110may have an end168located opposite the end bell166to which other components of the edger100,FIG. 1, may be attached. For example, the upper housing106,FIG. 1, may be attached to the end168. A shaft170may extend from the housing164and through the end bell166. The shaft170may be operatively attached to a abrasive disc or the like (not shown) that are located in the lower housing104. The shaft170may also be connected to or at least operatively connected to the above-described fan (not shown).

A circuit174may be located proximate the end168and may serve to monitor the operation of the motor110. The circuit174may have contacts or other connections that serve to electrically connect the circuit174to other components within the motor controller160,FIG. 2, as described in greater detail below. For example, the circuit174may monitor the speed of the shaft170in addition to the amount of current being drawn by the motor110. In one embodiment, electric power supplied to the motor110is supplied via the circuit174.

A side-cut away view of an embodiment of the motor110is shown inFIG. 4. The motor110depicted inFIG. 4is a brushless motor. The motor110may have a first fan178and a second fan180connected to the shaft170and located within the housing164. The fans178and180serve to cool the motor110. 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 magnet182is attached to the shaft170. At least one field winding184is attached to the housing164in the proximity of the magnet182. The current flow through the field winding184is controlled by the motor controller160,FIG. 2, and serves to control the speed of the shaft170. For example, the motor controller160may monitor the speed of the shaft170via the circuit174and adjust the current to the field winding184so as to maintain the speed of the shaft170regardless of the load experienced by the motor110.

Having described the motor110, the other components of the motor controller160will now be described.

Referring again toFIG. 2, the motor controller160may have an input180that 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 motor110is operating under its maximum load. Accordingly, the edger100,FIG. 1, is able to operate on most standard one-hundred ten volt circuits without causing circuit breakers to trip.

The input185is electrically connected to a switch186, which may be operatively connected to the switch116ifFIG. 1. Depending on the state of the switch186, the input185is either connected to a logic circuit187or a DC converter188. In summary, the logic circuit187detects the state or transition of the switch186prior to instructing other components within the motor controller160to operate. This prevents the motor110from operating unless the switch186is toggled. For example, the logic circuit187may detect the voltage provided by the input185. In the embodiment described herein, the voltage at the DC converter188is required to transition from a low voltage to a high voltage in order for the other components within the motor driver160to operate. This transition assures that the motor110will only operate when the switch186has transitioned from an off position to an on position. Thus, the motor110will not start if power is supplied at the input185when the switch186is in the on position. It should be noted that the switch186as shown inFIG. 2is in an off position.

One embodiment of the logic circuit187detects the voltage supplied at the input185by way of a contact188within the switch186. The voltage level at the contact188will be high when power is supplied to the input185and the switch is in the off position. When the switch186is toggled to the on position, the voltage level at the contact188will transition to a low voltage. Upon the transition from the high voltage level to the low voltage level, the logic circuit187may output a signal or instruction that enables other components within the motor controller160, including the motor110, to operate.

If the switch186is in the on position when power is supplied to the input185, the voltage level at the contact188will be low. Accordingly, the voltage level at the contact188will not transition from a high voltage to a low voltage. The lack of such a transition will prevent the logic circuit187from enabling other components in the motor driver160to operate. Accordingly, the motor110will not operate. However, operation of the motor controller160may be enabled by toggling the switch186to the off position and then to the on position. This toggling will generate the high to low voltage level on the contact188that is required in order for the logic circuit187to enable the operation of the motor controller160.

The DC converter188converts AC power supplied at the input185of the motor controller160to DC power for use by the motor110and other components in the motor controller160. The DC converter188may have an output190which 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 motor110.

The DC power supplied by the DC converter188is supplied to an input192of a low voltage power supply194and an input198of a phase drivers circuit200. It should be noted that DC power may be supplied to other components (not shown) within the motor controller160. As described in greater detail below, the phase drivers circuit200in conjunction with commutation logic204serves to supply electric power to the motor110.

The low voltage power supply194converts the DC voltage supplied by the DC converter188to a level more appropriate for low voltage components within the motor controller160. In the embodiment described herein, the low voltage power supply194has an output206that is electrically connected to the commutation logic204and microprocessor logic210. The low voltage power supply194may, as an example, be a switching power supply and may supply five volts DC.

The microprocessor logic210serves to control the operation of the motor110. For example, the microprocessor logic210may ultimately control the speed of the shaft170, including providing a slow start up speed. The microprocessor logic210may also cause power to be removed from the motor110in the event that the shaft170is unable to rotate. For example, if the shaft170or the abrasive disc (not shown) become jammed, the microprocessor logic210may cause power to be disconnected from the motor110.

The microprocessor logic210may have a first input212that is electrically connected to the logic circuit187. In one embodiment, the microprocessor logic210may have a second input214that is electrically connected to the commutation logic204as described in greater detail below. An output220of the microprocessor logic210may be electrically connected to an input222of a speed regulator226. It should be noted that the output220of the speed regulator226and the input222of the speed regulator226may, in some embodiments provide two-way communications between the microprocessor logic210and the speed regulator226.

The speed regulator226in combination with the speed control117provides for a user to set the speed at which the shaft170and, thus, the abrasive disc, spins. The speed regulator226may have an output228that outputs signals or data to an input230of the commutation logic204. As described in greater detail below, the user may adjust the speed control117in order to set the speed of the shaft170. As also described in greater detail below, the speed of the shaft170remains substantially constant as the physical load on the shaft170varies. Feedback within the motor controller160monitors the speed of the shaft170and compares it to the speed set by the speed regulator226. The motor controller160then adjusts the speed of the shaft170so that it corresponds to the speed established by the speed regulator226.

The commutation logic204monitors the data and other signals generated by the circuit174and generates data or other signals to control the speed of the shaft170. The input230of the commutation logic204is connected to the output228of the speed regulator226and an output232is connected to the second input214of the microprocessor logic210. The commutation logic204also has multiple inputs234from the motor110and multiple outputs236connected to the phase drivers circuit200. The inputs234may be electrically connected to the circuit174and may carry data regarding the performance of the motor170. The outputs236carry data indicating the current that is to be supplied to the motor110by the phase drivers200as described in greater detail below.

The phase drivers200has multiple inputs240connected to the multiple outputs236of the commutation logic204. The phase drivers200also have multiple outputs242connected to the motor170. The phase drivers200supply electric power to the motor110depending on signals or voltage levels at the multiple inputs240. The power is supplied to the motor110via the multiple outputs242. Therefore, low power supplied by at the multiple inputs240can regulate high power output at the multiple outputs242.

Having described the components of the motor controller160, its operation will now be described.

As described above, the logic circuit187determines whether the motor110may rotate depending on the state of the switch186. If the logic circuit187determines that the motor110may rotate, a signal is provided to the microprocessor logic210to active the motor110. The microprocessor logic210senses that the motor110is being started from a stopped position and outputs a signal via the output220to the speed regulator226, which causes the speed of the motor110to start slow and increase to a speed established by the setting of the speed control117. The slow start of the motor110serves to attenuate power surges on the components of the motor controller160. In addition, the slow start of the motor110reduces the initial torque on the edger100, which lessens the possibility that a user will suddenly lose control of the edger100during start up.

The speed information regarding the speed at which the motor110is to operate is transmitted to the commutation logic204by way of the output228. For example the speed information may correspond to a voltage or a binary number output at the output228of the speed regulator226. Thus, during start up, the output220of the microprocessor logic210causes the speed regulator226to output a slow speed instruction to the commutation logic204. The speed may increase as a ramp function until the speed established by the speed control117is achieved.

The commutation logic204outputs voltages or other signals on the outputs236, which causes the phase drivers200to output voltages on the outputs242. These voltages or signals correspond to the speed and/or power requirements of the motor110. The inputs234to the commutation logic200receive information regarding the status of the shaft170and the motor110. For example, the shaft speed and amount of current drawn by the motor110may be output to the commutation logic204, which may transmit this data to the microprocessor logic210. Therefore, the microprocessor logic210may monitor the motor, including the speed of the shaft170as it encounters various loads and may cause the commutation logic204to increase or decrease the voltage output by the outputs242accordingly. Therefore, the speed of the shaft170is maintained relatively constant under varying loads.

Should the commutation logic204detect that the shaft170is stationary and that high current is being supplied to the motor110, the commutation logic204may disable the phase drivers200. This disabling is due to the detection of the shaft170being jammed or overloaded. Accordingly, the motor110will shut down. If the motor110were to continue to receive electric power, it could overheat or cause other components in the motor controller160to overheat.