Abstract:
The present invention is directed to a lawn mower and more particularly to a system and method of charging a variety of batteries of the lawn mower including connecting the lawn mower to a towing vehicle, either directly or by placing the lawn mower on a trailer, towing the lawn mower, generating electricity upon towing the lawn mower utilizing a generator mechanically coupled to the lawn mower wheels or the wheels of the trailer. The generator converts the mechanical energy into electrical energy. The generator is electrically coupled to first type of battery and a second type of battery that is connected to the lawn mower and/or a first type of battery and a second type of battery that is connected to a charging station on the trailer. The system also includes a charging circuit for each of the first type of battery and the second type of battery.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Application 62/118,643 filed on Feb. 20, 2015. The disclosure of the above application is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates generally to power tool cordless systems. 
       BACKGROUND 
       [0003]    Lawn mowers used by landscaping providers are typically moved from location to location by placing the mower on a trailer and pulling the trailer by a driven vehicle, such as a pickup truck. Furthermore, mowers are typically powered by internal combustion engines to drive the mower wheels and the cutting blades. These mowers may also include an internal battery for powering electrical elements of the mower. Alternate mowers may include an electric motor and a battery for powering the electric motor wherein the electric motor drives the mower wheels and the cutting blades. 
         [0004]    Additionally, landscaping providers utilize cordless, battery operated power tool to provide various services including, for example, such tools as string trimmers, blowers, and drills. 
         [0005]    It would be desirable to provide a system and method for charging the mower batteries and/or the cordless power tool batteries during transportation of the mower from location to location. 
       SUMMARY 
       [0006]    In one general aspect, the present invention may include a lawn mower, comprising at least two wheels for driving the mower; at least one blade for cutting grass; a generator for generating electricity; an electric motor electrically coupled to the generator for receiving the generated electricity, the electric motor coupled to the at least two wheels for driving the at least two wheels and/or the at least one blade for driving the at least one blade; a charging circuit electrically coupled to the generator for receiving the generated electricity; and at least one receptacle for receiving a removable battery pack, the receptacle including an electrical interface for electrically coupling the receptacle to the charging circuit to provide a charging current from the charging circuit to the receptacle and a mechanical interface for receiving and physically coupling the battery pack to the receptacle, wherein the electrical interface and the mechanical interface are substantially similar to an electrical interface and a mechanical interface of a cordless power tool such that the battery pack may electrically and mechanically couple to the mower electrical and mechanical interfaces to receive a charging current from the charging circuit and to the power tool electrical and mechanical interface to provide a discharging current to the power tool to operate the power tool. 
         [0007]    In another aspect, the present invention may include a lawn mower comprising at least two wheels for driving the mower; at least one blade for cutting grass; a generator mechanically coupled to at least one of the at least two wheels, wherein the generator converts mechanical energy generated by the at least one of the at least two wheels into electrical energy as the at least two wheels rotate when the mower is being pulled on a road; a first charging circuit electrically coupled (a) to the generator for receiving electricity and (b) to the first battery for providing a charging current to the first battery; a second battery; and a second charging circuit electrically coupled (a) to the generator for receiving electricity and (b) to the second battery for providing a charging current to the second battery. 
         [0008]    In another aspect, the present invention may include a trailer for transporting a lawn mower, comprising a platform for supporting the mower; at least two wheels for supporting the platform on a road; a generator mechanically coupled to at least one of the at least two wheels, wherein the generator converts mechanical energy generated by the at least one of the at least two wheels into electrical energy as the at least two wheels rotate when the trailer is being pulled on the road; an electrical cable coupled at a first end to the generator for providing electricity; and a coupler connected to a second end of the electrical cable for electrically coupling to a mating coupler of the mower for providing electricity to the mower. 
         [0009]    In another aspect, the present invention may include a lawn mower, comprising at least two wheels for driving the mower; at least one blade for cutting grass; an electric motor electrically coupled to the at least two wheels for driving the at least two wheels and/or the at least one blade for driving the at least one blade when the motor is turning in a first direction and for generating electricity when the motor is turning in a second direction opposite the first direction; a charging circuit electrically coupled to the electric motor for receiving the generated electricity; at least one receptacle for receiving a removable battery pack, the receptacle including an electrical interface for electrically coupling the receptacle to the charging circuit to provide a charging current from the charging circuit to the receptacle and a mechanical interface for receiving and physically coupling the battery pack to the receptacle, wherein the electrical interface and the mechanical interface are substantially similar to an electrical interface and a mechanical interface of a cordless power tool such that the battery pack may electrically and mechanically couple to the mower electrical and mechanical interfaces to receive a charging current from the charging circuit and to the power tool electrical and mechanical interface to provide a discharging current to the power tool to operate the power tool. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The accompanying drawings illustrate preferred embodiments of the invention according to the practical application of the principles thereof, and in which: 
           [0011]      FIG. 1  illustrates a cordless system according to a first aspect of the invention; 
           [0012]      FIG. 2  is a partial rear view of a mower of the cordless system of  FIG. 1 ; 
           [0013]      FIG. 3  is a block diagram showing an exemplary drive apparatus for the mower of  FIGS. 1-2 ; 
           [0014]      FIG. 4  illustrates a first exemplary embodiment of a mower and a charging system for charging batteries of the cordless system of  FIGS. 1-2 ; 
           [0015]      FIG. 5  illustrates a second exemplary embodiment of a mower and a charging system for charging batteries of the cordless system of  FIGS. 1-2 ; 
           [0016]      FIG. 6  is a block diagram of an exemplary charging system including a charging station of  FIG. 5 ; 
           [0017]      FIG. 7  illustrates a third exemplary embodiment of a mower and a charging system for charging batteries of the cordless system of  FIGS. 1-2 ; 
           [0018]      FIG. 8  is an exploded view of an exemplary hub motor used in a trailer of  FIG. 7 ; 
           [0019]      FIG. 9  illustrates a fourth exemplary embodiment of a mower and a charging system for charging batteries of the cordless system of  FIGS. 1-2 ; 
           [0020]      FIGS. 10-11  illustrate a fifth exemplary embodiment of a mower and a charging system for charging batteries of the cordless system of  FIGS. 1-2  where  FIG. 10  shows the mower in a first position and  FIG. 11  shows the mower in a second position. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    The invention is now described with reference to the accompanying figures, wherein like numerals designate like parts.  FIGS. 1-2  show a mower  100 , which is preferably a riding mower. The mower  100  can be an electric mower which is driven by an electric motor, a gas mower which is driven by a gas engine, or a hybrid mower which has both an electric motor and a gas engine. 
         [0022]    One drive apparatus for such a hybrid mower  100  is described in U.S. Pat. No. 5,323,868, which is hereby incorporated by reference. Such a drive apparatus is shown in  FIG. 3 . The hybrid mower  100  may have a gas engine  101  to be driven by fuel such as gasoline, a generator  102  driven by the engine  101  for generating DC electricity, a battery  103  for accumulating and storing the electricity generated by the generator  102 , an inverter/rectifier  104  for converting DC electricity from the generator  102  and the battery  103  into AC electricity, an induction motor  106  to be driven by the AC electricity, and a transmission or gearbox  107  for transmitting the driving force of the motor  106  to a set of tires  108 . 
         [0023]    With such a drive apparatus, fuel such as gasoline is supplied to the engine  101  for rotation (at a predetermined RPM). The torque of the engine  101  is preferably transmitted to the generator  102  for conversion into DC electricity. Of the thus generated electricity, an amount sufficient to drive the motor  106  is preferably sent to the motor  106  via the inverter  104 . The surplus DC electricity is preferably accumulated in the battery  103  which is capable of accepting relatively high charging currents and being charged at high charging rates. 
         [0024]    The torque of the motor  106  is transmitted to the tires  108  via the transmission  107  to cause the hybrid mower  100  to travel. When the electricity sent to the motor  106  from the generator  102  is not enough to drive the motor  106 , the battery  103  provides supplemental power to the inverter  104  and thus to the motor  106 . The supply of electricity to the motor  106  is varied by controlling a built-in switching device of the inverter  104  to react accordingly to the extent of stepping on the accelerator or gas pedal. 
         [0025]    To lower the speed of the hybrid mower  100 , regenerative braking is used as a counterpart to engine braking. Regenerative braking is performed as the switching device built into the inverter  104  is controlled. During this regeneration, rotational energy is given to the motor  106  from the tires  108  via the transmission  107 . Regenerated electricity is produced from the motor  106 . The regenerated electricity is converted into DC electricity by the inverter  104 , and is then accumulated in the battery  103 . 
         [0026]    Persons skilled in the art will recognize that, if DC motors are used instead of the induction motor  106 , the entire electrical system of the hybrid mower  100  could be DC-based and thus obviating the need for inverter  104 . 
         [0027]    A second electric induction motor  109  is preferably connected to inverter  104 . The torque of the motor  109  is transmitted to a set of cutting blades  111  via a transmission  110  to cause the hybrid mower  100  to cut grass or vegetation. 
         [0028]    Also connected to the inverter  104  is a low charging rate charging circuit  105 , which can provide charging current to charge one or more power tool battery packs  115 , which are capable of accepting relatively low charging currents and being charged at relatively low charging rates. It should be understood that the terms “low” and “high” are simply intended to be relative terms. As such, a low charging rate charging circuit simply provides a charging current and a charging rate less than a high charging rate charging circuit and a high charging rate charging circuit provides a charging current and a charging rate greater than a low charging rate charging circuit. Such power tool battery packs  115  are described in US Patent Publication No. 2014/0272516, filed on Mar. 15, 2013, and U.S. Patent Application No. 62/000,112, filed May 18, 2014, which are hereby fully incorporated by reference. The power tool battery packs  115  can be connected to (1) a separate charger  120  for charging, (2) a power tool, such as drill  122 , and/or (3) an outdoor power tool, such as a hedge trimmer or chain saw  124 , for cutting vegetation, as shown in  FIG. 1 . The charging circuit  105  may also control as display  126 , as shown in  FIGS. 2-3 , in order to indicate to the user which of the power tool battery packs  115  have been fully charged and/or the state of charge of the power tool battery packs  115 . 
         [0029]    Persons skilled in the art will recognize that the high charging rate charging circuit may provide high charging currents and current rates to the battery  103  resulting in relatively high power transfers (at least 500 watts and preferably at 3.5 kilowatts) to the battery  103 . Depending on the characteristics of the battery  103 , the battery  103  could be provided with power transfers on the order of about 10 kilowatts and preferably 25 kilowatts. However the low charging rate charging circuit  105  may only provide power transfers below 500 watts, even if the nominal voltage of the power tool battery pack  115  (between about 14 volts and about 60 volts) is different than the nominal voltage of the battery  103  (between around about 12 volts and about 48 volts). 
         [0030]    Persons skilled in the art will recognize that the type of charging circuit  105  that is connected to inverter  104  is one that can preferably convert AC power into DC charging currents. However, charging circuit  105  can be connected to battery  103 , in which case the charging circuit  105  can control the amount of DC charging current sent to the different battery packs  115 . The charging circuit  105  may charge the power tool battery packs  115  according to the algorithms and sequences taught in US Patent Publication No. 2013/0335014, filed on Feb. 18, 2013, which is hereby fully incorporated by reference. 
         [0031]    Persons skilled in the art will recognize that, in an electric mower  100 , the charging circuit  105  could similarly be connected to an on-board mower battery or an inverter connected to the mower battery  103 . Similarly, in a gas mower  100 , the charging circuit  105  could similarly be connected to an on-board mower battery  103  or to an inverter/rectifier  104  connected to the mower battery  103  or to a generator  102  driven by the mower&#39;s gas engine  101 . 
         [0032]    Persons skilled in the art will recognize that providing a low charging rate charger circuit  105  will facilitate access to the charged power tool battery packs  115 , as the user would not have to walk over to a charger  120 . Instead a person driving the mower  100  can just drive the mower  100  to a location where the charged power tool battery packs  115  are needed. 
         [0033]    It may be advantageous to maximize charging time for the power tool battery packs  115  and/or the battery  103 . Accordingly,  FIGS. 4-10  illustrate different systems that may implement various methods for charging such batteries during transportation of the mower  100 . 
         [0034]    Referring to  FIG. 4 , a first exemplary embodiment of a mower and a charging system for charging batteries of the cordless system is illustrated. Therein, a trailer  200  is attached to a vehicle  300 . The trailer  200  may carry the front wheels  128  of the mower  100 , allowing the rear wheels  108  to rotate as the vehicle  300  travels to the next destination. As the wheels  108  rotate, rotational energy is provided to the motor  106  from the wheels  108  via the transmission  107 . Regenerated electricity is produced from the motor  106 . This regenerated electricity is converted into DC electricity by the rectifier  104 , and is then accumulated in the battery  103 . The regenerated electricity can also be used to power the charging circuit  105  and thus charge the power tool battery packs  115 . 
         [0035]    Preferably the trailer  200  is a powered trailer electrically connected to the battery of the vehicle  300 . The trailer  200  may have a front fixed portion  202  attached to a towing hitch  201  of the vehicle  300 , and a rear movable portion  204  pivotally attached to the front fixed portion  202 . A motor  206  may cause the rear movable portion  204  to pivot relative to the front fixed portion  202 . A user may control the rotation of the rear movable portion  204  via control buttons  208 . The rear movable portion  204  may have a flap  210  pivotally attached thereto, in order to facilitate loading the mower  100  onto the trailer  200 . 
         [0036]    Referring to  FIGS. 5-6 , a second exemplary embodiment of a mower and a charging system for charging batteries of the cordless system is illustrated. Therein, a trailer  250  is attached to the vehicle  300  via a standard towing hitch  201 . The trailer  250  has a set of wheels  251  connected to a generator or an alternator  252  via a belt or chain  253 . Accordingly, as the trailer  250  is pulled by the vehicle  300 , at least one of the wheels  251  and the generator/alternator  252  generate electricity. 
         [0037]    The mower  100  may be connected to the generator/alternator  252  via a cable  255 . The generated electricity can be used to charge the power tool battery packs  115  and/or the battery  103 . As shown in  FIG. 5 , the cable  255  may be connected to the mower  100  at a point D (see  FIG. 3 ), which in turn is connected to a high charging rate charging circuit  113  for charging the battery  103 . Persons skilled in the art will recognize that the charging circuit  1113  may be disposed within the mower  100 , or outside of the mower  100 . For example, the charging circuit  113  could be integrated with the cable  255  or the generator/alternator  252 . 
         [0038]    The trailer  250  may have a charging station  254  with a charging circuit  256  connected to the generator/alternator  252  via an electrical connection  257 . The generator/alternator  252  generates high currents and is capable of providing power for the high charging rate charging circuits. The charging circuit  256  receives the high current electricity generated by the generator/alternator  252  and provides charging currents to the power tool battery packs  115  via the charging circuit  105 . 
         [0039]    The charging station  254  may also charge a supplemental battery  103  that is separate from the mower  100 . In this manner, if the battery  103  in the mower  100  is discharged beyond the allowed parameters, the user can quickly swap the discharged battery  103  with a charged battery  103 . Referring to  FIG. 6 , the generator/alternator  252  can power a high charging rate charging circuit  113  for charging the supplemental battery  103 . The generator/alternator  252  may also power a low charging rate charging circuit  105  for charging the power tool battery packs  115 . The charging circuit  105  may also be powered by the supplemental battery  103 . A relay switch  258  can be used to select the power source for the charging circuit  105 , where the relay switch  258  selects the supplemental battery  103  as the power source when the supplemental battery  103  is connected to the charging circuit  113 . This embodiment takes full advantage of the high currents generated by the generator  252  by charging the high charge current battery  103  in the mower with high charging currents by the high charging rate charging circuit  113  in the mower (relatively quickly) and/or by charging the alternate high charge current battery  103  in the charging station  254  with high charging currents by the high charging rate charging circuit  113  in the charging station  254  (relatively quickly) and/or by charging the low charge current battery  115  in the mower  100  with low charging currents by the low charging rate charging circuit  105  in the mower  100  (relatively slowly) and/or by charging the low charge current battery  115  in the charging station  254  with low charging currents by the low charging rate charging circuit  105  in the charging station  254  (relatively slowly). Additionally, the batteries  103  (either in the mower  100  or the charging station  254 ) can charge the batteries  115  (in the mower  100  or the charging station  254 , respectively) with low charging currents by the low charging rate charging circuit  105  (in the mower  100  or the charging station  254 , respectively) when power is not being generated by the generator  252 , i.e., when the trailer  300  is not moving. In this manner, in one situation, the high charge current batteries  103  (in the mower  100  and the charging station  254 ) can be charged quickly with high charging currents when the trailer  300  is moving and the high currents are available (taking full advantage of the available high charging currents) and then the high charge current batteries  103  can charge the low charge current batteries  115  at the low charging currents when the high charging currents are not available. 
         [0040]    A pivotable gate  260  may be connected to trailer  250 . A flange  262  may be disposed on a platform  263  of the trailer  250 . The flange  262  may have a curved slot  264 . A handle  266  extends through slot  264  and threadingly engages the gate  260 . With such construction, the user can rotate the gate  260  and lock it at a particular pivotal position by rotating handle  266 . 
         [0041]      FIGS. 7-8  illustrate a third exemplary system for charging batteries and/or battery packs, where like numerals refer to like parts. Instead of having a separate generator/alternator  252 , this embodiment includes a wheel hub motor  270  cooperating with the wheel  251 . An exemplary hub motor can be found disclosed in US Publication No. 2014/0374178, filed Dec. 26, 2013, which is hereby fully incorporated by reference. 
         [0042]    As shown in  FIG. 8 , the hub motor  270  has a stator  272  containing electric magnets and electronics for controlling the generated magnetic fields, and a rotor  274  slipped over the stator  272 . The wheel  251  is bolted onto the rotor  274  via a set of bolts  276 . Rather than using the hub motor  270  for driving the wheel  251 , the hub motor  270  is used herein for power generation. Accordingly, as the trailer  250  is pulled by the vehicle  300 , the wheel  251  rotates, causing the rotor  274  to rotate around the stator  272 . Because the rotor  274  preferably has a set of permanent magnets, the magnetic field of such magnets induces a current in a set of coils surrounding the electric magnets in the stator  272 . 
         [0043]    This generated current can be conducted via the cable  255  to the high charging rate charging circuit  113  for charging the high charge current battery  103 . Persons skilled in the art will recognize that, as described above, the high charge current battery  103  can be used to power the low charging rate charging circuit  105  to charge power tool battery packs  115 . 
         [0044]      FIG. 9  illustrates another alternate exemplary trailer  250 , where like numerals refer to like parts. Instead of having a generator/alternator  252  driven by the wheel  251 , the trailer  250  preferably has a separate generator assembly  280 , which has a wheel  282 , a generator/alternator  284 , and a transmission  286  connecting the generator wheel  282  and the generator/alternator  280  so that rotation of the generator wheel  282  causes the generator/alternator  280  to generate electrical power. 
         [0045]    This generated current can be conducted via the cable  255  to the high charging rate charging circuit  113  for charging the high charge current battery  103 . Persons skilled in the art will recognize that, as described above, the battery  103  can be used to power the low charging rate charging circuit  105  to charge the power tool battery packs  115  or the current can be provided directly to the charging circuit  105  from the generator/alternator  280  via the cable  255  and a switch  258 . 
         [0046]    Persons skilled in the art will recognize that the generator assembly  280  can be separate from the trailer  250  and that it preferably can be removed and installed on different trailers, as necessary or desired. 
         [0047]    Referring to  FIGS. 1 and 10-11 , the mower  100  may have a pivotable hitch  140  for engaging a ball hitch  302  of the vehicle  300 . The hitch  140  may be moved between a storage position (shown in broken lines in  FIG. 1 ) and an extended position (shown in solid lines in  FIG. 1 ) for engaging the ball hitch  302 . 
         [0048]    Persons skilled in the art will recognize that it is desirable to lock the hitch  140  in the extended position and/or the storage position. A pin (not shown) can be used to lock the hitch  140  in the desired position. 
         [0049]    The hitch  140  may have a cam surface  142  which can contact and ride on a cam surface  304  of ball hitch  302 . Accordingly, the user can drive the mower  100  towards the vehicle  300 . The hitch  140  will contact and ride on the cam surface  304 , lifting the hitch  140 . As the mower  100  moves further towards the vehicle  300 , the hitch  140  will move above and then fall on a ball post  306 , thereby hitching the mower  100  to the vehicle  300 . The battery  103  can be then be charged as described above while the vehicle  300  tows the mower  100 , causing the wheels  108  to rotate. 
         [0050]    Persons skilled in the art will recognize that some mowers  100  may have transmissions  107  that do not easily allow for rotation of the wheels  108  at high speed. Accordingly, the mower  100  may be provided with at least one generator wheel assembly  290 . The generator wheel assembly  290  preferably has an arm  292  pivotally connected to the mower  100 , and a wheel  294  preferably disposed at a distal end of the arm  292 . The wheel  294  is operatively connected to a generator/alternator (not shown) in a similar manner as described above so that, when the wheel  294  rotates, the generator/alternator produces charging currents that can charge the battery  103  and/or the power tool battery packs  115 . 
         [0051]    Preferably the arm  292  is connected to a motor  296  which can rotate the arm  292  (and thus wheel  294 ) downwardly towards the ground. The motor  296  preferably has sufficient torque to lift up the mower  100 , so that the wheels  108  are not contacting the ground. Instead the mower  100  is supported above the ground by the ball hitch  302  and the wheel(s)  294 . 
         [0052]    Alternatively, the arm  292  may be disposed in the lower position (not contacting the ground). The arm  292  may be fixedly attached to the mower  100  (thus obviating the need for the motor  296 ). Instead of driving the mower  100  into the ball hitch  302 , the user would move the hitch  140  onto the ball hitch  302 , then lift and push the mower  100 . In this manner, the hitch  140  can engage the ball hitch  302 , and the wheels  108  are lifted so that they are not contacting the ground. Instead the mower  100  is supported above the ground by the ball hitch  302  and the wheel(s)  294 . 
         [0053]    Persons skilled in the art may recognize other additions or alternatives to the means disclosed herein. However, all these additions and/or alterations are considered to be equivalents of the present invention.