Hybrid Electric Lawnmower

PRIOR APPLICATIONS

0001This application is a continuation in part of and claims priority to U.S. patent application Ser. No. 11/550,104 filed Oct. 17, 2006, and is a continuation in part of and claims priority to U.S. patent application Ser. No. 11/550,476, filed Oct. 18, 2006.

BACKGROUND OF THE INVENTION

0002The present invention is related to an electric lawnmower and more particularly to an electric lawnmower having a boost/conserve power feature, a dual mode power supplying providing power to a lawn mower motor as well as dual electric motors powering the cutting blades.

BRIEF DESCRIPTION OF THE DRAWINGS

0003<figref idref="DRAWINGS">FIG. 1</figref> is a perspective view of the hybrid mower with power boost conserve features of the present invention;

0004<figref idref="DRAWINGS">FIG. 2</figref> is an exploded view of the hybrid mower of <figref idref="DRAWINGS">FIG. 1</figref>;

0005<figref idref="DRAWINGS">FIG. 3</figref> is a close up view of the controls for the hybrid mower of <figref idref="DRAWINGS">FIG. 1</figref>;

0006<figref idref="DRAWINGS">FIG. 4</figref> is a close up view of the controls for the hybrid mower of <figref idref="DRAWINGS">FIG. 1</figref> with the interlock handle switch activated;

0007<figref idref="DRAWINGS">FIG. 5</figref> is a bottom view of the hybrid mower of the present invention depicted in <figref idref="DRAWINGS">FIG. 1</figref> in combination with the AC power input plug;

0008<figref idref="DRAWINGS">FIG. 6</figref> is a circuit diagram of one option of a power control circuit for use with the hybrid mower with boost conserve feature of <figref idref="DRAWINGS">FIG. 1</figref>;

0009<figref idref="DRAWINGS">FIG. 7</figref> is a circuit diagram of one option of the power inverter and hybrid control depicted in <figref idref="DRAWINGS">FIG. 6</figref> for the lawnmower depicted in <figref idref="DRAWINGS">FIG. 1</figref>;

0010<figref idref="DRAWINGS">FIG. 8</figref> is one option of the power control circuit for use with the hybrid mower with boost conserve feature depicted in <figref idref="DRAWINGS">FIG. 1</figref>;

0011<figref idref="DRAWINGS">FIG. 9</figref> is one option of the power control circuit for use with the hybrid mower with boost conserve feature for the lawnmower depicted in <figref idref="DRAWINGS">FIG. 1</figref>;

0012<figref idref="DRAWINGS">FIG. 10</figref> is one option of the power control circuit for use with the hybrid mower with boost conserve feature as depicted in <figref idref="DRAWINGS">FIG. 1</figref>;

0013<figref idref="DRAWINGS">FIG. 11</figref> is a bottom view of an alternative mower design having dual blade construction;

0014<figref idref="DRAWINGS">FIG. 12</figref> is a schematic of one option of the power control circuit and motor design for one embodiment of a dual motor electric mower;

0015<figref idref="DRAWINGS">FIG. 13</figref> is a schematic of one option of the power control circuit and motor design for one embodiment of a dual motor electric mower.

DETAILED DESCRIPTION OF THE EMBODIMENT

0016A hybrid electric lawnmower is described herein and set forth in the claims and is partially depicted in the perspective view of <figref idref="DRAWINGS">FIG. 1</figref> wherein the hybrid mower <b>10</b> is shown having a deck <b>50</b> with an outwardly extending handle <b>55</b>. Positioned on the outwardly extending handle <b>55</b> is a plurality of controls <b>20</b>, the controls <b>20</b> incorporating a control box <b>24</b>, an AC plug <b>22</b> and an AC receptacle <b>23</b>. Additionally, contained within the deck <b>50</b> are a number of features including, but not limited to, the power control and supply described herein as well as a DC motor, a blade, and other necessary features for making the electric lawnmower described herein operable to function as desired. Such function and structure include the DC motor to drive the blade, the DC motor powered by alternative power supplies which include 120VAC line voltage or DC power supply such as a batter pack. The motor drives the blade and the power supply system of the hybrid electric mower allows the user to select the power source whether it be AC power supply or DC power supply. In either selection, the power control system of the electric mower provides adequate voltage to the motor. Further, a selection is available for the user of the present embodiment to drive the motor in either conserve or boost mode, conserve mode utilizing less power from the power source as boost mode thereby increasing charge time for each full battery charge under such selection, should the DC operation mode be selected, although both conserve and boost mode may be operable in AC operating mode also.

0017Further design enhancements may include the addition of a second electric motor in order to increase the cutting width of the electric lawn mower without increasing the blade diameter. Increasing blade diameter is problematic in that the total amount of air resistance with longer blades increases substantially the power drain on the battery due to substantial air movement resistance.

0018While many options and various embodiments are depicted herein for operation of the hybrid lawnmower with power boost and conserve features, it is to be understood that a wide variety of alternative structures may be utilized in order to incorporate the novel functionality and structures described and claimed. Further, while certain electrical connections and circuits are described for providing operable functionality, it is to be understood that one of ordinary skill in the art would understand the disclosure and functionality described herein, as well as the embodiments and variations described, and include or replace operative alternative structures to perform the same or similar claimed functional elements. As such, the embodiments and particular elements set forth in the description herein are not deemed to be restrictive and are merely provided within the limits of the teachings hereof to be exemplary and should not unnecessarily narrow or limit the controls and electronics which are used to describe various embodiments and examples set forth.

0019The hybrid mower with a boost conserve feature of the present embodiment is depicted in <figref idref="DRAWINGS">FIG. 1</figref> with the deck <b>50</b> on a plurality of wheels such that the hybrid mower <b>10</b> may roll, be powered or be pushed over terrain required to be cut by the blade <b>51</b>. The specific configuration of the hybrid mower <b>10</b> of the present embodiment, as depicted in <figref idref="DRAWINGS">FIG. 1</figref>, is not necessarily limiting in that the many structures and switches which are depicted may be positioned on multiple surfaces or in multiple positions on the hybrid mower <b>10</b> and thus, the particular location and limitation of the depictions and structure set forth are considered to be merely exemplary.

0020The hybrid mower <b>10</b> of the present embodiment incorporates controls near the handle <b>55</b> such that they may be readily accessible to the operator of the mower <b>10</b>. These handles and controls, more clearly and specifically disclosed in <figref idref="DRAWINGS">FIG. 3</figref>, include a power selection switch <b>21</b>, a boost and conserve switch <b>26</b>, both of which may be located on the control box <b>24</b>. Integrated within the control box <b>24</b> may also be a circuit breaker <b>28</b>, a clutch release <b>32</b> and a blade clutch handle <b>31</b>, the blade clutch handle <b>31</b> acting as an interlock handle switch to engage and disengage the DC motor <b>56</b> from rotating the blade <b>51</b>. Also shown with the controls <b>20</b> on the control box <b>24</b> is the AC power line <b>22</b> which may be directly plugged into AC line voltage which is typically 60 Hz 120 Volts. The AC power line <b>22</b> has a plug receptacle <b>23</b> for directly connecting to an extension cord or other device in order to provide AC electrical power to the hybrid mower <b>10</b> of the present embodiment.

0021The hybrid mower <b>10</b> of the present embodiment is designed to be operated on either AC line voltage from an AC power source such as a wall plug or other AC source, or from a DC battery pack which is mounted on the deck <b>50</b> or in close conductive and operative relationship with the DC motor <b>56</b> depicted. The hybrid mower <b>10</b> of the present embodiment is so designed that the operator may operatively select functionality of the hybrid mower <b>10</b> and the motor <b>56</b> by either AC or DC power, the DC alternative coming from the battery pack <b>52</b> which may be rechargeable. The rechargeable battery pack <b>52</b> is mounted, as depicted in <figref idref="DRAWINGS">FIG. 2</figref>, on the deck <b>50</b>. Additionally, as depicted in the controls <b>20</b>, the hybrid mower with boost and conserve feature <b>10</b> of the present embodiment includes an option a boost conserve switch <b>26</b> which provides the functionality of increasing or decreasing the voltage provided to the DC motor <b>56</b> thereby increasing or decreasing the rotational speed of the blade <b>51</b> based upon the setting of the boost conserve switch <b>26</b>. As can be commonly understood, the boost conserve switch <b>26</b> may increase or decrease the voltage and thereby increase or decrease the actual drain on the battery pack <b>52</b> or other power supply due to the increased current provided to the DC motor <b>56</b>. Thus, as the hybrid mower with power boost conserve feature <b>10</b> of the present embodiment is run in the DC power selection option depicted by the DC selection shown in <figref idref="DRAWINGS">FIG. 3</figref> and selected by the power selection switch <b>21</b>, the battery pack <b>52</b> may be brought in electrical conductivity with the DC motor <b>56</b> and the boost and conserve switch <b>26</b> may be placed in a conserve switch setting so as to reduce the rotational speed of the blade <b>51</b> thereby decreasing the rate of drain of the battery pack <b>52</b> and also increasing the run and operation time of the hybrid mower <b>10</b> of the present embodiment per charge. Alternatively, the DC motor running based upon AC line voltage may use less current while running at such user selection. Thus, the boost and conserve feature as shown and depicted in the examples and as is effectuated in the present embodiment through the use of the boost conserve toggle switch <b>26</b> of <figref idref="DRAWINGS">FIG. 3</figref> may be integrated with either power selection of the AC power input line or DC power input line to the DC motor <b>52</b>. Further descriptions and implementations of such examples will be described hereinafter.

0022As shown in <figref idref="DRAWINGS">FIG. 3</figref>, the controls <b>20</b> of the hybrid mower <b>10</b> of the present embodiment is depicted with a blade clutch handle <b>31</b> and a clutch release <b>32</b> such that the blade clutch handle <b>31</b> must be operatively held in close relationship to the handle <b>55</b> as is commonly understood and known by those of skill in the art in order to engage the DC motor <b>56</b> and correspondingly the blade <b>51</b>. The blade clutch handle <b>51</b>, when placed and held in close relationship to the handle <b>55</b> of <figref idref="DRAWINGS">FIG. 3</figref>, engages an interlock handle switch as will be described herein which may be a double throw switch, and which operates to act as a user's dead man switch in order to disengage the DC motor if released. It is desirable in order to be able to discontinue rotation of the blade <b>51</b> upon release of a manually actuatable handle within a limited and short period of time. Thus, the interlock handle switch as depicted herein is integrated with the blade clutch handle <b>31</b> and acts to operatively disengage the DC motor and also cause resistive breaking of the motor and thus the blade upon release of the handle <b>31</b>.

0023Turning now to particular embodiments and examples as depicted herein, the present embodiment is directed towards a hybrid electric lawnmower which has a boost and conserve feature. Electric lawnmowers, and particularly battery powered mowers, have historically had limited mowing time per charge and have had increased weight due to the battery pack. Thus, prior alternatives had been a corded electric mower with the corresponding restriction of managing a cord and limited power from the household current. When operating off the battery pack, it has been difficult to mow larger lawns due to the limited mowing time per charge and possibly due to greater height of the lawn which would correspondingly reduce the charge and run time for the battery pack.

0024In the present inventive hybrid mower <b>10</b> depicted, the hybrid control system depicted allows for the hybrid mower <b>10</b> to be powered from regular household AC line voltage or from a DC voltage battery pack. The battery pack may be designed to have a lower operating voltage available which may be lower than the average peak voltage of the household current. This arrangement may be provided in order to allow the mower to run in a possible conservation mode in order to preserve battery run time under less demanding grass conditions. Alternatively, when the mower is plugged in to AC household current or line voltage or when additional voltage is tapped from the battery pack or from a battery associated with the battery pack, the hybrid mower <b>10</b> of the present embodiment may selectively be operated in a boost or power mode, the boost mode allowing the mulching of taller grass or pick up various debris or pine cones from the yard during operation.

0025It may also be desirable in one of the present inventive embodiments, to provide a battery pack <b>52</b> which is easily removable from the lawnmower deck <b>50</b>, as is depicted in <figref idref="DRAWINGS">FIG. 2</figref>. The hybrid mower <b>10</b> of the present embodiment may be used without the battery pack so as to be more easily maneuverable in sloped areas due to the reduced weight of not having the battery pack <b>52</b> installed. It may also be easier to stow the mower and charge the battery pack <b>52</b> separately or alternatively charging the battery when the mower <b>10</b> is still in operation. The DC motor <b>56</b>, depicted in <figref idref="DRAWINGS">FIG. 2</figref>, may be a permanent magnet type DC motor and may be designed to receive power from the battery and/or from the hybrid power controller which will be described herein. The DC motor <b>56</b> may be provided to power the rotating blade <b>51</b> while cutting vegetation and the motor <b>56</b> may act as a generator in order to provide resistive breaking after deactivation of the inter-lock handle switch described thereby providing a resistive load to stop the blade quickly once the blade interlock handle <b>31</b> is released. The motor <b>56</b> shown in <figref idref="DRAWINGS">FIG. 2</figref> may be designed to further provide a fan to promote cooling of the DC motor <b>56</b> thereby providing air circulation across the brushes and through the motor. Alternative embodiments with multiple motors or with multiple commutators selectively operating in series or in parallel may also be provided.

0026As previously described, the blade <b>51</b> may be provided in order to mulch or cut vegetation. Typical blade tip speeds of about 16,000 to 19,000 ft. per minute non-cutting with a blade tip speed during cutting of vegetation of between 12,000 to 18,000 ft. per minute with a proportionate horsepower rating for the DC motor of about 1.5. Higher speeds may be indicated when operating from AC line voltage while lower speeds may be recognized operating off of Battery DC voltage. Alternatively, in a low power or conservation mode, the run time can be considerably longer with a battery life expected to be increased by 50% and wherein the speed of the DC motor <b>56</b> correspondingly decreases to drive the blade <b>51</b> at approximately 14,000 ft. per minute blade speed as measured at the tip of the blade. The various speeds of the blade <b>51</b> can correspond to a plurality of voltage outputs from the hybrid power supply as seen by the DC motor <b>56</b>. Namely, to provide higher speed functionality of the blade, a voltage of sixty-six or seventy-two volts DC may be presented to the DC motor with a 300 watt/hr batter charge capacity. Alternatively, in conservation or low speed mode, thereby corresponding to higher battery pack run time duration or less current draw from the power supply, the power consumption may be significantly reduced by providing 60 volts or less to the DC motor <b>56</b>. These various power consumption modes may be provided through the use of the boost and conserve selection switch <b>26</b> which, as can be seen from the examples depicted herein, may be a single pole double throw switch as shown in order to increase the voltage through the various means depicted and described in the multiple examples hereof

0027Thus, in conservative mode the corresponding blade speed may be less than 15,000 ft. per minute blade tip measurement and preferably at 14,000 ft. per minute blade tip measurement or less thereby significantly increasing the battery pack charge run time should the battery pack be in operation and the power selection switch <b>21</b> be selected in DC mode as depicted in <figref idref="DRAWINGS">FIG. 3</figref>. In such an instance, the 60 volts may be provided to the DC motor which, as depicted in the embodiment of <figref idref="DRAWINGS">FIG. 2</figref>, the battery pack <b>52</b> may be provided with a series of five batteries connected in series, each of the batteries providing 12 volts. Alternatively, should the boost/conserve switch <b>26</b> be operated in the boost mode while the power switch <b>21</b> is in the DC mode, and additional or secondary battery which may be integrated with or separated from the battery pack <b>52</b> depicted in the exemplary drawing, may be brought in series with the battery pack <b>52</b> power supply thereby increasing the voltage to 66 or 72 volts, depending on the ultimate desirability and blade speed to be operated. Of course, variations may be provided in the configuration and implementation while running in DC mode for the battery pack depicted herein as this example is provided merely for descriptive purposes only and many other embodiments including bringing batteries in parallel, series, or providing additional power sources may be utilized.

0028While this example of the conserve and boost switch has been provided in the operation of DC mode, alternative embodiments and increase in motor speed may be provided while also running in AC mode will be described herein. Such embodiments may include increasing the step down voltage from the power supply controller as presented to the DC motor or alternatively bringing in series the secondary battery while also operating in AC mode thereby increasing the DC voltage presented to the motor and resulting in an increase rotational speed of the blade. Thus alternative embodiments are shown and depicted wherein the power supply of the present embodiment generates DC power to the motor and wherein the boost or increased voltage may be derived from either the power supply by various techniques known and depicted, or by providing additional voltage from the battery pack or secondary batter, either of which may result in increased operational speed of the motor and blade speed.

0029One other aspect of the present embodiment of the hybrid mower <b>10</b> of the present embodiment is the ability to provide a user selectable power supply to a DC motor driving the blade <b>51</b>. In the presently depicted hybrid mower <b>10</b> of the present embodiment, a DC motor <b>56</b> is provided to rotate blade <b>51</b> on the mower deck <b>50</b> due to its energy use and supply characteristics. A user selectable alternative power supply or power selection switch <b>21</b> is provided in order that the DC motor <b>56</b> may be user switchable from power sources, namely from an AC 120 volt 60 Hz power input representing line voltage should an extension cord or line voltage be readily accessible or alternatively, to a battery pack DC voltage provided on board of the mower, both power supplies selectable by the operator and both power supplies driving the same motor mounted on the lawnmower housing or deck <b>50</b>. Such an option is highly desirable and unique in that the user may selectively operate the mower from various user selectable inputs representing alternative power inputs, a first power input being provided at the power selection switch <b>21</b> representing a power input line from a battery pack <b>52</b>, and a second power input being provided at the power selection switch <b>21</b> representing the AC line <b>22</b>. Further, as an alternative design element, the power control circuit <b>60</b> could include a solid state relay which, as an example, has a zero crossing circuit for voltage detection to activate a triac or other relay device to automatically connect the electric motors to line voltage, when plugged into the power control circuit. Such user selectable power selection can thus be automated by a automated voltage or other detection circuit or may be actuated by the switch <b>21</b> herein described.

0030Turning to an exemplary embodiment shown in <figref idref="DRAWINGS">FIG. 6</figref> wherein a power control circuit <b>60</b> is depicted providing, among other things, the boost and conserve power features of the present embodiment. The DC electric motor <b>56</b> is shown in electrical connectivity with the various power control circuit elements <b>60</b>, <b>100</b> which include the inter-lock handle switch <b>31</b>, for example being a double pole double throw switch, a circuit breaker <b>28</b> being, as depicted herein, a 35 amp breaker, a boost/conserve switch <b>26</b>, in this example being a single pole double throw switch, a power selection switch <b>21</b>, in this example being a single pole double throw switch, a battery pack <b>52</b> which is depicted as a 60 volt DC battery pack providing 60 volts presented to the motor <b>56</b> when operatively selected by the power selection switch <b>21</b>, and a hybrid AC/DC controller <b>100</b> which serves as a power inverter or step down controller for converting the line voltage 120 VAC presented by the plug <b>23</b>. The battery pack is shown as sharing a common ground with other portions of the power control circuit but may be in electrical connectivity with the power control circuit in many known and understood manners without actual connected electrical wiring as long as the user operation of the lawn mower is actuated through activation of the various switches. In this present example, the boost selection switch <b>26</b> provides an increased voltage to the motor <b>56</b> by virtue of modifying an input resistive value or timing signal value to the pulse width modulation control unit <b>120</b>, which will be described herein, in order to alter the gating of the IGBT thereby affecting the voltage wave form at the output of the power inverter or step down controller <b>100</b>. The in rush current limiter may be provided as shown in order to prevent oversaturation of the circuit during the initial startup and energizing of the circuit. The rectifier <b>110</b> as is commonly understood rectifies the voltage from AC to DC, in this case utilizing a full bridge rectifier as shown. However, many different forms of providing a step down controller are known in the art and the depictions set forth are not to be considered unduly limiting.

0031As depicted in <figref idref="DRAWINGS">FIG. 6</figref>, the design consists of the AC wall plug <b>23</b> which connects to the hybrid AC/DC controller <b>100</b> acting as a voltage converter which in turn is connected to a single pole double throw power selection switch <b>21</b> and a single pole double throw boost switch <b>26</b>. The boost switch <b>26</b> is the boost conserve switch depicted and described herein and it provides resistive loads to the CMOS micro-controller for the pulse width modulation control <b>120</b> depicted when selected and opens the contacts when off. The power selection switch <b>21</b> toggles the DC motor between the output of the step down controller <b>100</b> and the DC battery voltage source <b>52</b>. The output of the power selection switch <b>21</b> feeds a voltage meter shown which may be connected in parallel with the double pole double throw inter-lock handle switch <b>31</b>, the inter-lock handle switch <b>31</b> toggling between shorting the DC motor <b>56</b> through resister R<b>1</b> to ground and connecting the output of the power selection switch <b>21</b> through a circuit breaker <b>28</b> to the DC motor <b>56</b>.

0032In this embodiment as depicted in <figref idref="DRAWINGS">FIG. 6</figref>, the boost switch <b>26</b> may provide increased voltage to the motor <b>56</b> when the hybrid mower <b>10</b> of the present embodiment is plugged in and running off of line voltage AC power. Such boost may be effectuated by modifying the pulse width modulation control <b>120</b> through alteration of the input resistive load at input pin <b>7</b> of the micro-controller shown in <figref idref="DRAWINGS">FIG. 7</figref>. More description of the power inverter and/or step down controller <b>100</b> of the presently inventive power supply will be set forth herein.

0033Turning to an additional embodiment for the power supply circuit <b>160</b> of the present embodiment in <figref idref="DRAWINGS">FIG. 8</figref>, this embodiment provides an AC wall plug <b>23</b> which connects to an AC voltage to the hybrid AC/DC controller <b>100</b> which in turn is connected to the power selection switch <b>21</b> which allows toggling between output of the AC/DC hybrid controller <b>100</b> when in the AC selection and to a boost conserve switch <b>26</b> and alternative power source when in the DC position. The boost conserve switch <b>26</b> toggles between shorting the positive side of the battery source <b>52</b> directly to the boost switch <b>26</b> went off and connecting the battery source <b>52</b> in series with the secondary or boost battery <b>64</b> before connecting to the power selection switch or AC/DC switch <b>21</b>. The power selection switch <b>21</b> then feeds a voltage meter V which is connected in parallel with an inter-lock handle switch <b>31</b>, here depicted as a double pole double throw switch. The inter-lock handle switch <b>31</b> toggles between shorting the DC motor <b>56</b> through a resistor R<b>1</b> to ground and connecting the output of the power selection switch <b>21</b> through the circuit breaker <b>28</b> to the DC motor <b>56</b>.

0034As depicted, in the example shown in <figref idref="DRAWINGS">FIG. 8</figref>, additional voltage is provided to the DC motor <b>56</b> when the hybrid mower is positioned in the DC power selection option and activation of the boost switch <b>26</b> thereby providing an additional 6 volts DC to the 60 volts DC provided by the battery <b>52</b>. A secondary battery <b>64</b> provides additional voltage to the motor thereby increasing the motor speed and corresponding blade speed through actuation of the boost/conserve switch <b>26</b> to the boost setting. Thus, the power control circuit or power supply <b>160</b> depicted in <figref idref="DRAWINGS">FIG. 8</figref> allows the operator while in the DC battery operation mode to increase the operating speed of the motor <b>56</b> corresponding to the additional voltage provided by the secondary battery <b>64</b>. Controls are also provided allowing the operator to select between the operation of the motor <b>56</b> through the use of line voltage, namely 120 VAC, or through the use of the battery pack <b>52</b>. Depicted herein is a secondary boost battery <b>64</b> which is provided as separate to the battery pack <b>52</b>, but it may be more practical to provide a secondary boost battery <b>64</b> in combination with and contiguous to the battery pack <b>52</b> as assembled and shown in the figures. Thus, the secondary boost battery <b>64</b> may be continuous with the battery pack <b>52</b> or may be separate but is provided to add additional voltage to the motor <b>56</b> in order to modify the operating output voltage of the power supply as presented to the motor <b>56</b>.

0035The hybrid AC/DC controller <b>100</b> as shown provides both power inverter and step down capabilities in order to modify and regulate the 120 VAC to the proper voltage required to run the DC motor <b>56</b>. However, these functions are provided to be only exemplary. The controller <b>100</b> acts as an inverter via rectifier <b>110</b> and also to properly modulate the voltage via the PWM controller <b>120</b> and associated gates. The power inverter and step down controller <b>100</b> may be part of the power supply or power control module <b>60</b>, <b>160</b>, <b>260</b> and <b>360</b> as needed, or may be excluded, depending on the voltage characteristics of the input line voltage and the requirements of the electric motor implemented in the present design.

0036An alternative construction for the power control is the power supply circuit <b>260</b> depicted in <figref idref="DRAWINGS">FIG. 9</figref> wherein both 120 VAC may be provided to supply power to the motor <b>56</b> while optionally a 60 volt DC battery may be provided as operatively selectable by the user through the power selection switch <b>21</b><i>a</i>. As depicted in this example, the boost switch <b>26</b><i>a </i>is operative to bring in series a secondary battery <b>64</b> which is 6 volts DC (when set in “BOTH” mode) with the voltage provided by the hybrid controller <b>100</b> of the power supply or the battery pack <b>52</b>. The secondary battery <b>64</b>, as previously described and as depicted in this embodiment of the power control circuit <b>260</b>, may be in combination with the battery pack or secondary and separate thereof. Additionally, as shown in the example, the 6 volt battery is brought into the circuit in series with the DC output of the hybrid control <b>100</b> or with the battery pack <b>52</b>. Also, many variations for the structure, assembly and actual value of the secondary battery <b>64</b> for all embodiments may be provided in order to increase the voltage to the motor <b>56</b>. As depicted in <figref idref="DRAWINGS">FIG. 9</figref>, the power selection switch <b>21</b><i>a </i>further provides for three settings allowing user selectable options of powering the DC motor <b>56</b> by either 120 VAC, direct battery pack connection or a hybrid BOTH connection. When operating in the strictly 120 VAC mode, the hybrid AC to DC control <b>100</b> is depicted regulates and modulates the voltage for proper supplying of voltage to the DC motor <b>56</b>. Alternatively, the power selection switch <b>21</b><i>a </i>provides for a DC operation whereby the motor <b>56</b> is operated merely by the battery pack <b>52</b>. A third option is placement of the power selection switch <b>21</b><i>a </i>into the BOTH mode wherein there may be a limited amount of power contribution from the battery. In such instance, voltage drops caused by increased load on the motor <b>56</b> may result in increased contribution from the battery pack <b>52</b>. Additionally, as depicted in the embodiment shown, the boost conserve switch <b>26</b><i>a </i>may be provided for contribution of additional voltage from the secondary battery <b>64</b> when the power selection switch <b>21</b><i>a </i>is placed in either the BOTH or DC mode. In such an instance, the secondary battery <b>64</b> is brought in series with the voltage contribution from either the power supply <b>100</b> or the battery pack <b>52</b>.

0037Turning to <figref idref="DRAWINGS">FIG. 10</figref>, an alternative construction and embodiment of the power control and supply circuit <b>360</b> is depicted. In the example depicted, the power supply circuit <b>360</b> consist of a 120 VAC wall plug <b>23</b> which connects to the hybrid AC controller <b>100</b> which in turn is connected to an exemplary single pole double throw boost switch <b>26</b> thereby allowing the circuit to bypass boost battery <b>64</b> when off or be connected to the boost battery <b>64</b> when on. Additionally, the circuit continues to an exemplary single pole double throw power selection switch <b>21</b> which toggles between output of the speed selection switch <b>26</b> when in the AC position and the DC battery voltage source <b>52</b> when in the DC position. The power selection switch <b>21</b> feeds a voltage meter V which is connected in parallel with an exemplary double pole double throw inter-lock handle <b>31</b>, the inter-lock handle switch <b>31</b> toggling between short in the DC motor <b>56</b> through a resistor R<b>1</b> to ground and connecting the output of the power selection switch <b>26</b> through a circuit breaker <b>66</b> to the DC motor <b>56</b>. In this example of the power control circuit <b>360</b>, the boost or secondary battery <b>64</b> is brought in parallel with the power pack <b>52</b> or with the output of the hybrid controller <b>100</b> which may increase the current capacity for the motor when in higher speed or boost mode.

0038Multiple variations of power control module or power supply may be provided and are described herein. When mentioned herein as a hybrid power controller, power supply, power control module, step down controller or hybrid controller, these terms are collectively meant to imply providing electricity to the motor placed on the mower housing. No single element set forth in the exemplary embodiments provided herein, namely the power supply elements of the switches, battery packs, circuit breakers, inverters and modulation elements are to be unnecessarily applied to the interpretation of these terms. In fact, the power supply circuit collectively described herein may be implemented through the use of a significant number of alternative structures for regulation, modulation, controlling or limiting the proper voltage or power to the motor implemented in the examples herein. No unnecessary limitation should be interpreted from the particular use of the term controller, inverter, regulator or regulation or modulation as depicted herein, as one of ordinary skill in the art would be enabled through the teachings hereof to provide significant variations to the particular embodiments and examples disclosed in the figures and stated in the described examples.

0039Turning to the exemplary power inverter and in combination step down controller <b>100</b> which acts as a portion of the power control module, the hybrid controller <b>100</b> receives as input 120 volts AC which, in this example, is inverted utilizing a full bridge rectifier <b>110</b> depicted in <figref idref="DRAWINGS">FIG. 7</figref>. An in rush current limiter is provided also to prevent current surges during initial loading of the circuit and prevent further damage or over-saturation. A number of different inverter designs may be used in order to provide voltage rectification. As depicted in the present example, a full bridge rectifier may be utilized but this may be replaced with other known inverter circuitry as is available and known in the art.

0040In addition, as depicted in <figref idref="DRAWINGS">FIG. 7</figref>, an optional boost switch may be provided which may correspond to the boost switch <b>26</b> depicted in <figref idref="DRAWINGS">FIG. 6</figref>. In the present exemplary embodiment, the boost switch may be operable to modify the input to the pulse width modulation controller <b>120</b> which defines the voltage output for the step down controller <b>100</b>. As shown, a micro-controller is utilized in order to set the appropriate pulse rate for the PWM control and feeds into the insulated gate bi-polar transistor (IGBT) which provides the switching or pulse gate driver <b>122</b> for the DC output of the hybrid AC/DC control <b>100</b>. Thus, the hybrid controller <b>100</b> incorporates, but does not necessarily require, the utilization of voltage rectification and a voltage rectifier as is necessary in combination with variations of voltage modification such as a pulse width modifier. However, multiple options for step down voltage and control are known and may be utilized such as diode controls, triac controls, MOSFET controls and the like. Many of these are well known in the art and may be utilized in the step down controller and power inverter in combination as described herein. Additionally, as depicted, the pulse width modulation control circuit <b>120</b> receives as input in one possible embodiment the ability to modify the voltage by use of the boost switch. The boost switch in this embodiment modifies the reference signal fed into pin <b>7</b> of the micro-controller for the reference value which operates to modify the gating of the IGBT and therefore, the voltage characteristics of the DC output depicted. The boost mode depicted provides the alternative function of a boost integrated with the power inverter and step down controller. As shown integrated with the controller <b>100</b> in <figref idref="DRAWINGS">FIG. 6</figref>, the boost switch can be alternatively provided in many connections and this integrated boost switch may be integrated with many of the other alternative embodiments.

0041As is known, many variations of a step down controller and inverter may be utilized and in general, the power control module of the present embodiment may utilize power input of 120 VAC and which incorporates many switches and controls for electrically connecting the DC motor to either the 60 volt DC battery or the DC output of the hybrid power controller. This may include utilization of a power source switch as indicated wherein the power source switch effectively has a first power input as a connection of the power control module of the DC output of the power inverter and step down controller <b>100</b> or receive as a second input the 60 volt DC of the battery pack, the power selection switch providing the ability of the operator to switch between 120 VAC power and 60 VDC power from the battery pack. The power selection switch may be directly connected to the DC motor, in this exemplary embodiment a 60 volt DC motor which operates the blade. The 60 volt DC motor may be operationally modified by utilization of a boost switch which is optional in many embodiments depicted herein, the boost switch changing voltage applied to the DC motor from 60 volts by an incremental value thereby increasing rotational speed of the blade as necessary by the operator. Such increase in blade speed, as previously indicated, may be necessitated by thicker grass or due to other items necessarily being mulched by the hybrid mower <b>10</b> of the present embodiment. This boost/conserve function which is shown herein provides the ability through the many embodiments disclosed to increase the voltage of the power control module and thereby increases the rotational speed of the blades. As indicated, this may be desirable for short periods of time and may provide a first power output of the power control module, the first power output higher than a second power output, the second power output being a conserve feature wherein the DC motor draws less current and thereby increases the battery life charge of the battery pack. However, such feature does not have to be implemented, as is clearly seen herein, only with the use of DC operation and DC power input as it is apparent that the increase rotational speed (boost) feature may be implemented also with 120 VAC wall power by increasing the DC voltage output of the hybrid AC/DC control <b>100</b> or by adding supplemental DC power supply from the operating batteries, whether the primary or secondary.

0042Turning now to <figref idref="DRAWINGS">FIGS. 11-13</figref>, an alternative embodiment of the electric lawnmower of the present invention is depicted. In such an alternative construction, the electric lawnmower <b>500</b> has a first and a second blade <b>551</b>A and <b>551</b>B mounted to a housing <b>550</b>. Driving each of the blades, <b>551</b>A and <b>551</b>B are a first and second motor <b>552</b>A and <b>552</b>B as depicted in <figref idref="DRAWINGS">FIGS. 12 and 13</figref>. As is commonly understood, the dual motor alternative construction as is depicted, may substantially use similar power control circuitry with the modification in the series or parallel connection of the DC motors <b>552</b>A and <b>552</b>B to the power supply voltage. As is understood, it is desirable to provide the DC motors with either 120VAC line power which is current rectified or with the battery pack supplied DC electrical power. In the construction and multiple embodiments provided, two blades may be provided to cut vegetation within and below the deck <b>550</b> of the electric lawnmower <b>500</b>. A total cutting width of approximately 21 inches may be provided wherein each of the blades may be about 10.4 inches. As is commonly understood, by attempting to cut a relatively large diameter with a single blade, such as the entire 21 inches of the housing width, excessive battery drain and power consumption will be experienced due to the known issue of air movement resistance encountered by the blade. The air movement load goes up exponentially as related to the blade speed thus adding a significantly higher load in addition to the normal vegetation cutting resistance load. The faster the blade rotates and the longer the blade causes a significant proportion of the power supply to be used in movement of air as opposed to cutting of vegetation. Thus, for cutting of wider diameters, it may be preferable to utilize two motors and blades working in tandem. By utilizing two motors as opposed to a single motor with an increased rotational speed, significant power savings may be experienced and run time lengths for the power supply battery as well as power consumption in both DC and AC operations will be significantly reduced. Additionally, as is known in the art, when using dual motors <b>552</b>A and <b>552</b>B, such dual motor implementation may preferably not be used in series in conjunction with battery operation due to the motors running at half speed, i.e. sharing the battery pack supplied voltage in series. Thus, in preferred implementation, although not necessarily required, for dual motor use, the DC electric motors may be preferably placed in parallel as is depicted in <figref idref="DRAWINGS">FIG. 12</figref> in certain operations, such as when operated by the battery pack, and possibly in series in others, such as when connected to higher line voltage. However, the DC motors may be placed in either operation as is deemed necessary. Also, power usage may not become an issue when providing line voltage through the hybrid AC to DC controller wherein the AC current is rectified for operation of the DC motors depicted.

0043As depicted in <figref idref="DRAWINGS">FIG. 12</figref>, the dual DC motors <b>552</b>A and <b>552</b>B for the power control and supply system <b>520</b> of the present embodiment, depicts the DC motors in parallel as shown. A circuit breaker may be provided in combination with the interlock handle switch as previously described in order to operationally connect and disconnect the motors as selected by the user through the blade clutch handle <b>31</b>. Further, an AC/DC operational switch may be provided for selection of either power supply, either AC line voltage or DC battery power supply as previously described. Further, a hybrid AC/DC controller may be utilized to implement rectification of the 120 VAC to adequate supply of DC current to the motors <b>552</b>A and <b>552</b>B. Further, the boost switch may be provided in combination with the hybrid controller or separately as previously described as combinations of these individual elements may be selected to one of ordinary skill in the art and generally is considered to be taught within the operational specifications hereof

0044In an embodiment, the dual blade DC motor combination may provide a 21 inch path of cutting vegetation wherein similar rotational speeds of 16,000 to 19,000 feet per minute blade speed may be experienced either on battery or on the AC line voltage with the higher rotational speed indicated when operating using line voltage. Such rotational speed indicates a potential of 5,800 to 6,900 RPM. These speeds typify the efficiency of the motor during a non-cutting environment. In actual cutting of vegetation, the rotational speed of the blade tip may be 12,000 to 18,000 feet per minute, again with the higher rotational speeds indicated when operating on line voltage. These speeds relate to approximately 4,300 to 6,500 RPM on each of the two blades providing 21 inch cutting diameter. Similar motors may be provided as previously described for implementation of the electric lawnmower of the present invention. Further, the horsepower at cutting speed may be anywhere from 1.5 to 2.0 HP with the battery capacity of approximately 480 watt hours as necessary. Excellent cutting at these speeds with either the single motor or dual motor implementation may be experienced with adequate blade speed, cutting action and suction experienced within the lawnmower deck or housing. Mulching may also be accomplished when operating at these speeds and may be increased by implementation of the boost feature previously described which would be available to both DC electric motors during operation in this embodiment if implemented in one of the many various boost and conserver implementations previously described. Referencing again <figref idref="DRAWINGS">FIG. 12</figref>, both motors are depicted in parallel combination with the motors seeing approximately 60 volts from the power supply. When the motors are in such parallel connectivity, as one motor is loaded disproportionately due to various factors from either air resistance or vegetation and cutting resistance, the second motor slows down due to the reduced power available from the battery caused by the internal resistance and the higher amperage of the power supply as is depicted. Such self adjustment of the motor and hence blade speeds provides an automated self regulation of both motors.

0045Given the power supply and control embodiment depicted in <figref idref="DRAWINGS">FIG. 13</figref>, the user may select either AC or DC operation which places the two motors <b>552</b><i>a </i>and <b>552</b><i>b </i>in either series or parallel configuration. When in DC mode, the battery <b>52</b> supplies constant current and may result in better performance of the motors. Further, when placed in DC mode, the motors are in parallel and as one motor is loaded disproportionately the second motor may slow down due to the reduced power available from the battery pack caused by the internal resistance of the power supply design and motor configuration and higher amperage.

0046Turning to the alternative construction and embodiment of the power supply and control circuitry of <figref idref="DRAWINGS">FIG. 13</figref>, the power supply and control circuit <b>560</b> indicates that the dual DC motors <b>552</b>A and <b>552</b>B are connected to the output of the AC/DC power selection switch <b>521</b> which toggles the power supply of the circuit from the full bridge rectifier <b>501</b> when in the AC position and to the DC battery source <b>52</b> when in the DC position as is depicted. The output of the power selection switch <b>521</b> feeds the voltage meter shown which is connected in parallel with the double pole, double throw interlock handle switch <b>31</b>. The interlock handle switch <b>31</b> toggles between short in the DC motors <b>552</b>A and <b>552</b>B through a resistor, R<b>1</b> to ground and connecting the output of the power selection switch <b>521</b>, a three pole double throw switch in this disclosed embodiment, through circuit breaker <b>28</b> to the dual DC motors <b>552</b>A and <b>552</b>B. When the power selection switch <b>521</b> is in the AC selection position, the dual motors M<b>1</b> and M<b>2</b> are connected in series thereby splitting the voltage output of the rectifier. In such operation, the full bridge rectifier may provide 120VDC with 60V the seen by each motor. When the AC/DC power selection switch <b>521</b> is in the DC position, the motors M<b>1</b> and M<b>2</b> are connected in parallel thereby each sharing in the DC voltage output of the battery pack. The battery, being a constant current power supply, may provide better performance of the DC motors M<b>1</b> and M<b>2</b> in parallel and thus the connection as is described may be provided with the capability of switching between parallel and series connectivity of the motors M<b>1</b> and M<b>2</b> depending on the power source. Further, as disclosed in <figref idref="DRAWINGS">FIG. 13</figref>, a full bridge rectifier or possibly other current rectification is depicted wherein the 120VAC is input into the hybrid controller (not depicted as previously shown for simplicity). The full bridge rectifier in this embodiment may readily be replaced by known current rectification circuitry which have been previously disclosed herein or which are known in the art. Thus, the rectifier depicted may be replaced by other current rectification means to rectify the current from AC to DC. These known systems include but are not limited to pulse width modulation which may readily be implemented herein.

0047When in AC mode as selected from the user selectable power selection switch shown in <figref idref="DRAWINGS">FIG. 13</figref>, the total current going through many of the switches and electronic circuit elements presented herein may be one half of that in the parallel or battery mode given the embodiments depicted as a result of the rectification of the current and positioning of the loads. In other words, as shown in <figref idref="DRAWINGS">FIG. 13</figref>, the battery pack provides 60VDC which is shared by the dual motors in parallel and the AC input line provides 120VDC to be split by the dual motors in series in the disclosed embodiments. The response to uneven loading also may be more desirable as previously described in parallel as opposed to in series mode since, when in series mode, as one motor is disproportionately loaded and slows down, the other motor will speed up. The actual speed modification of the motors in series however may be mitigated due to the nature of the air resistance to the blades and the significant amount of energy and load required to move the air in the mower housing. The relationship between air movement resistance and blade speed is an exponential relationship thus adding a significantly higher load the faster the blade thus tending to cause the blades to operate at similar speeds in these embodiments. However, either combination of either series or parallel connection of the two DC motors as is depicted may readily be implemented and such a description is set forth herein is not deemed limiting as a preferable implementation as one of ordinary skill in the art may implement series or parallel connectivity of the motor as the system necessarily requires.

0048In both configurations of the dual motor design depicted, the ability and functionality of the boost and conserve features are still present in that the blade speed for both motors may be reduced in a conserve mode, particularly when operating off of the DC battery power supply in order to increase charge life. As shown in <figref idref="DRAWINGS">FIG. 12</figref>, a boost and conserve switch and feature may be implemented in conjunction with the hybrid controller shown. However, many differing combinations of the boost and conserve feature previously described may be well understood to be applicable to either design and power supply shown. In conjunction with the power supply and control depicted in either embodiment, a secondary battery pack may be utilized as discussed herein to increase the voltage output of the DC operation and power supply thereby increasing the blade speed for both motors while also allowing battery use to be conserved in a second state thereby increasing overall run life per charge. Alternatively, increased voltage may be provided directly from the hybrid controller as depicted when drawing power from AC power supply. Similarly alternative constructions may be implemented in the embodiment shown in the various Figures and embodiments.

0049Many configurations are available for the hybrid mower discussed herein. While the hybrid mower has been described for many embodiments, the invention presented is not limited to the specific structures provided. The invention and claims are intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims and teachings hereof The scope of the claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.