Patent Description:
Document <CIT> discloses a lawn mower with a management assembly for controlling rotation of blades responsive to operation of a powerhead of the lawn mower. The lawn mower comprises: a first blade <NUM> disposed within a blade housing and coupled to a shaft <NUM>; a second blade <NUM> disposed within the blade housing and coupled to the shaft <NUM>; and a blade coupler configured to selectively couple the first blade and/or the second blade to the shaft to produce different cutting performance conditions based on which of the first blade and/or the second blade is coupled to the shaft. The first blade and the second blade are each of a different type in terms of energy consumption or cutting characteristics.

Yard maintenance tasks are commonly performed using various tools and/or machines that are configured for the performance of corresponding specific tasks. Certain tasks, like grass cutting, are typically performed by lawn mowers. Lawn mowers themselves may have many different configurations to support the needs and budgets of consumers. Walk-behind lawn mowers are typically relatively compact, have comparatively small engines and are relatively inexpensive. Robotic mowers can be even smaller, and operate autonomously. Meanwhile, at the other end of the spectrum, riding lawn mowers, such as lawn tractors, can be quite large.

Although each of these different types of mowers clearly has significant differences in weight, size, cost and sometimes also capabilities, they are all generally constructed around the same basic principle of operation. In this regard, a power source is used to enable a power unit (e.g., a motor or engine) to provide the motive force that causes blades to rotate on a shaft and cut grass. Gasoline or petrol engines had been dominant means by which to provide the motive force for rotating the blades for many years. However, more recently, battery powered devices have been becoming more prominent.

Practical limitations had initially effectively restricted battery power to applications in smaller devices such as robotic mowers. However, battery technology advances gradually enabled walk behind mowers to also be battery powered. Now, even riding lawn mowers such as lawn tractors and mowers with zero (or near zero) turn radius are also being designed to be powered by battery.

Given these (and future) advances in battery technology, it should be expected that more and more battery powered models of lawn mowers (i.e., electric mowers) will hit the market. Product costs for electric mowers are directly related to the battery size and the charger capacity for the charger that is used to charge the battery. Accordingly, finding innovative solutions for reducing power consumption, while also minimizing impact on the quality of the cut provided by the electric lawn mower will provide cost and performance advantages within this context.

Some example embodiments may therefore provide for improved power management capabilities for lawn mowers.

In an example embodiment, a lawn mower may be provided. The lawn mower may include a blade housing configured to house at least a first blade and a second blade, a shaft disposed to rotate within the blade housing, a powerhead configured to selectively turn the shaft responsive to application of power from a power source, and a blade coupler configured to selectively couple the first blade and/or the second blade to the shaft to produce different cutting performance conditions based on which of the first blade and/or the second blade is operably coupled to the shaft.

In another example embodiment, a power management assembly for controlling rotation of blades of a blade assembly responsive to operation of a powerhead of a lawn mower may be provided. The power management assembly may include a first blade disposed within the blade housing and selectively operably coupled to a shaft, a second blade disposed within the blade housing and selectively operably coupled to the shaft, and a blade coupler configured to selectively couple the first blade and/or the second blade to the shaft to produce different cutting performance conditions based on which of the first blade and/or the second blade is operably coupled to the shaft.

Some example embodiments now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all example embodiments are shown. Indeed, the examples described and pictured herein should not be construed as being limiting as to the scope, applicability or configuration of the present disclosure. Rather, these example embodiments are provided so that this disclosure will satisfy applicable legal requirements. Furthermore, as used herein, the term "or" is to be interpreted as a logical operator that results in true whenever one or more of its operands are true. As used herein, operable coupling should be understood to relate to direct or indirect connection that, in either case, enables functional interconnection of components that are operably coupled to each other.

<FIG> illustrates a side view of a walk-behind lawn mower <NUM> of an example embodiment. However, it should be appreciated that the walk-behind lawn mower <NUM> is just one example of an outdoor power equipment device on which an example embodiment may be practiced. In other examples, the outdoor power equipment device could be a riding lawn mower or a robotic lawn mower of any type. For this example, an operator may be located at an operator station located behind the lawn mower <NUM>. However, for a riding lawn mower, the operator may ride on a seat at either a forward, middle or rear portion of the device. For the robotic lawn mower, there may not be an operator actively involved in operation of the device during cutting operations, as the robotic lawn mower may be capable of autonomous operation.

The lawn mower <NUM> of <FIG> includes a blade housing <NUM> to which a handle assembly <NUM> is attached. The operator station may be at a distal end of the handle assembly <NUM> relative to the blade housing <NUM>. The blade housing <NUM> may house a blade assembly <NUM> (see also <FIG>) having more than one rotatable cutting blade. The cutting blades may be suspended above the ground via one or more instances of a rotatable shaft (e.g., a drive shaft - not shown in <FIG>) that may be turned responsive to operation of a powerhead <NUM>, such as an electric motor. Operation of the powerhead <NUM> may be initiated by a key, switch, electronic ignition or other similar device. In some cases, the key, switch, electronic ignition or the like may be located at the powerhead <NUM>. However, in other cases, the key, switch, electronic ignition or the like may be located at the operator station.

The lawn mower <NUM> may include a mobility assembly on which a substantial portion of the weight of the lawn mower <NUM> may rest when the lawn mower <NUM> is stationary. The mobility assembly may also provide for movement of the lawn mower <NUM>. In some cases, the mobility assembly may be driven via power from the powerhead <NUM> that may be selectively provided to ground engaging wheels <NUM>, which make up the mobility assembly. In other cases, the wheels <NUM> may simply roll responsive to a push force from the operator. In some examples, the wheels <NUM> may be adjustable in their respective heights. Adjusting the height of the front wheels and/or the back wheels may be employed in order to provide a level cut and/or to adjust the height of the cutting blade. In some embodiments, a local wheel height adjuster may be provided at the front wheels and/or the back wheels. However, in other embodiments, remote wheel height adjustment may also or alternatively be possible (e.g., from the operator station or elsewhere on the lawn mower <NUM>).

Rotation of the cutting blades of the cutting assembly <NUM> may generate grass clippings, and/or other debris that may be ejected from the blade housing <NUM>. In some cases, the clippings/debris may be ejected from a side or rear of the blade housing <NUM>. When a rear discharge is employed, many such lawn mowers may employ a collector <NUM> to collect discharged clippings/debris. However, collectors may also be used for side discharge models in some cases. The collector <NUM> may be removable to enable the operator to empty the collector <NUM>, and the collector <NUM> may be made of fabric, plastic or other suitable materials.

As noted above, example embodiments may also be practiced with robotic lawn mowers and riding lawn mowers. In such cases, the components discussed above may be included (or modified) along with other components to form the robotic lawn mower or riding lawn mower. Thus, the components of <FIG> are merely provided as non-limiting examples of some of the components that may be common to lawn mowers that may employ the technology associated with example embodiments.

<FIG> illustrates a partially cutaway view of the inside of the blade housing <NUM> of <FIG>. Meanwhile, <FIG> illustrates a functional block diagram of various components of a multi-blade mower according to an example embodiment. It should be appreciated that generic housings associated with robotic lawn mowers or riding lawn mowers could easily be substituted for the blade housing <NUM> in other example embodiments. In the examples of <FIG> and <FIG>, the powerhead <NUM> is battery powered from battery <NUM>. Although the powerhead <NUM> is battery powered in this example, it should be appreciated that the powerhead <NUM> could alternatively be powered by a gasoline or petrol engine and example embodiments described herein could still be employed. When battery powered, the battery <NUM> may be a rechargeable battery that can be charged at a charging station (not shown). In an example embodiment, the powerhead <NUM> may be operably coupled to (and selectively power or turn) shaft <NUM>. Shaft <NUM> is then selectively coupled to either one or both of the blades of the blade assembly <NUM>. The blades of the blade assembly <NUM> include a first blade <NUM> and a second blade <NUM>. However, it should be appreciated that the blade assembly <NUM> could also include additional blades (e.g., multiple vertically stacked blades). The first and second blades <NUM> and <NUM> (along with any additional blades if more than two are employed) are each operably coupled to the shaft <NUM> via a blade coupler <NUM>. In an example embodiment, the first and second blades <NUM> and <NUM> may be blades that are each of a different type at least in terms of their energy consumption and/or cutting characteristics. For example, one blade may be used for better mulching capability, and the other may be used for better discharge or bagging capability. The different characteristics of the blades may also include having different lengths. For example, the first blade <NUM> may be a <NUM> inch blade, and the second blade <NUM> may be an <NUM> inch blade. Other structural differences that impact energy consumption and/or cutting characteristics may also be employed in some alternative embodiments.

In some cases, the first blade <NUM> (e.g., the blade located closest to the ground and therefore having the lowest elevation relative to the ground) may be a low flow and/or low energy blade. In other words, the first blade <NUM> may be shaped or otherwise designed to generate a relatively low amount of airflow and flow energy responsive to rotation thereof. A flat blade design may provide such a low flow, low energy profile. In this regard, since a flat blade design encounters less air as it rotates, the amount of flow energy is minimized. The flat blade may therefore be relatively easy to turn and consume less energy. Meanwhile, the flat blade may also generate less flow energy and therefore provide less capability for driving the flow of clippings into, for example, the collector <NUM> of <FIG>. The flat blade may therefore be a better blade for mulching operations.

In some cases, the second blade <NUM> (e.g., the blade located farthest away from the ground and therefore having the highest elevation relative to the ground) may be high flow and/or high energy blade. In other words, the second blade <NUM> may be shaped or otherwise designed to generate a relatively high amount of airflow and flow energy responsive to rotation thereof. A winged blade design may provide such a high flow, high energy profile. In this regard, since a winged blade design has uneven surfaces (e.g., some of which may be created by "wing" structures on the blade or near the distal ends thereof), the winged blade encounters more air as it rotates, thereby generating turbulent flow and increasing the amount of flow energy generated by rotation of the blade. The winged blade may therefore be relatively harder to turn and consume more energy. Meanwhile, the winged blade may also generate more flow energy and therefore provide increased capability for driving the flow of clippings into, for example, the collector <NUM> of <FIG>. The winged blade may therefore be a better blade for discharge and bagging operations.

The first and second blades <NUM> and <NUM> may be positioned coaxially (e.g., with the shaft <NUM> forming the common axis thereof) in a vertically stacked arrangement. Thus, for example, the separation between the first and second blades <NUM> and <NUM> may be provided using vertical separation. In other words, the second blade <NUM> may be mounted at a higher elevation (i.e., farther from the distal end of the shaft <NUM> than the first blade <NUM>) than the first blade <NUM>. In some example embodiments, the vertical space between the first and second blades <NUM> and <NUM> may be less than one inch. Moreover, in some cases, the vertical space may be about <NUM>/<NUM> inch or in the range of <NUM>/<NUM> inch to <NUM>/<NUM> inch.

In some cases, the first and second blades <NUM> and <NUM> may each be capable of being selectively coupled to the shaft <NUM> to rotate therewith based on a position or arrangement of the blade coupler <NUM>. For example, the blade coupler <NUM> may have a first position in which the blade coupler <NUM> only physically engages or couples the first blade <NUM> to the shaft <NUM>, a second position in which the blade coupler <NUM> only physically engages or couples the second blade <NUM> to the shaft <NUM>, and a third position in which the blade coupler <NUM> physically engages or couples both the first blade <NUM> and the second blade <NUM> to the shaft <NUM>. When a respective one of the first and second blades <NUM> and <NUM> is physically engaged or coupled to the shaft <NUM>, the respective one of the first and second blades <NUM> and <NUM> may rotate with the shaft <NUM>. When not physically engaged or coupled to the shaft <NUM>, the corresponding first or second blade <NUM> or <NUM> that is not coupled/engaged may be allowed to either freewheel or may not move even though the shaft <NUM> turns.

In an example embodiment, the blade coupler <NUM> may shift positions or arrangements in order to operably couple either one or both of the first and second blades <NUM> and <NUM> to the shaft <NUM> responsive to actuation locally or remotely. Thus, for example, the blade coupler <NUM> may be operable by an electrical repositioner <NUM> or a mechanical repositioner <NUM> being adjusted to make a selection regarding which blade(s) to couple to the shaft <NUM>. One or more clutch elements, collar devices, protrusions, or other implements may be used to couple the first and second blades <NUM> and <NUM> to the shaft <NUM>. In some cases, one of the blades may always be coupled, and the other can be optionally coupled. For example, the first blade <NUM> may always be coupled to the shaft <NUM>, and the second blade <NUM> can optionally be also coupled to the shaft <NUM>. As an alternative, the second blade <NUM> may always be coupled to the shaft <NUM>, and the first blade <NUM> can optionally be also coupled to the shaft <NUM>. As another alternative, each of the first and second blades <NUM> and <NUM> may be optionally coupled to the shaft <NUM> either alone or in combination with the other blade.

The mechanical repositioner <NUM> may physically extend a detent, protrusion, or other coupling member from the shaft <NUM> and into a portion of the blade (or vice versa) in order to operably couple the two in response to the mechanical repositioner <NUM> being operated. The electrical repositioner <NUM> may electrically or magnetically operate to extend a detent, protrusion, or other coupling member or magnetically couple components of the blade to the shaft <NUM> (or vice versa). In some cases, the electrical positioner <NUM> or mechanical positioner <NUM> may further include a brake mechanism for friction coupling that stops or slows a non-selected blade. For example, if the electrical positioner <NUM> or mechanical positioner <NUM> is operated to select the first blade <NUM> for rotation with the shaft <NUM>, the second blade <NUM> may also be engaged (e.g., by the brake mechanism or friction coupling) in order to slow or stop the second blade <NUM>.

<FIG> illustrate a side view of a portion of the first and second blades <NUM> and <NUM> on the shaft <NUM> along with a vertically movable example of the blade coupler <NUM>. In this example, the blade coupler <NUM> may be moved vertically along the shaft <NUM> in order to be positioned in one of three horizontally distinct positions. In this regard, arrow <NUM> in <FIG> illustrates that the blade coupler <NUM> could be moved upward or downward from the position shown. However, it should be appreciated that in the position shown in <FIG>, the blade coupler <NUM> contacts both the first blade <NUM> and the second blade <NUM>, and couples both simultaneously to the shaft <NUM> so that both the first blade <NUM> and the second blade <NUM> will rotate with the shaft <NUM>. Of note, the shaft <NUM> may have one or more orifices <NUM> disposed along the shaft <NUM>. The blade coupler <NUM> may include a protrusion (not shown) that may fit into an instance of the orifice <NUM> to fix the blade coupler <NUM> to the shaft <NUM>. The blade coupler <NUM> may also include a fitting arrangement with any blade with which the blade coupler <NUM> is in contact in order to carry the corresponding blade with the blade coupler <NUM> responsive to movement of the shaft <NUM>. Thus, for example, in <FIG>, the blade coupler <NUM> engages (and therefore carries) each of the first and second blades <NUM> and <NUM> when the shaft <NUM> rotates.

In the example of <FIG>, the blade coupler <NUM> has been vertically shifted downward in order to only engage the first blade <NUM> to the shaft <NUM>. Meanwhile, in the example of <FIG>, the blade coupler <NUM> has been vertically shifted upward in order to only engage the second blade <NUM> to the shaft <NUM>. Accordingly, the examples of <FIG> illustrate three separate coupling states that can be achieved by three different distinct vertical repositionings of the blade coupler <NUM>. As noted above, the three different vertical positions of the blade coupler <NUM> may each correspond to a respective different engagement state with the blades of the blade assembly <NUM>, and the three different vertical positions can be achieved by operation of either an electrical repositioner <NUM> or a mechanical repositioner <NUM>. However, it should be appreciated that fewer states (e.g., two states) could be used in some cases, as also explained above. Moreover, different structures for the blade coupler <NUM> may also be used in alternative embodiments.

<FIG> illustrates a bottom view (i.e., looking upward from the ground) of the blade assembly <NUM>, and shows how the blade coupler <NUM> may also be coaxial with the shaft <NUM> in some cases to engage the portion of any blade that the blade coupler <NUM> has vertical overlap with. As can also be appreciated from the example of <FIG>, the blade coupler <NUM> may maintain a lag angle <NUM> between the first and second blades <NUM> and <NUM> during rotation of the shaft <NUM>. In the example of <FIG>, the lag angle <NUM> is about <NUM> degrees. However, the lag angle <NUM> could be any desired angle between <NUM> and <NUM> degrees. In still other examples, the lag angle <NUM> may be variable since the blade coupler <NUM> may be configured to provide a slip engagement with one of the first blade <NUM> or the second blade <NUM> and fixed engagement with the other. In such an example, the slip engagement may be provided by a frictional coupling that carries the slip engaged blade at a lower speed than the speed of the shaft <NUM> as the shaft <NUM> turns. Thus, the two blades may turn at different speeds even through driven by the same shaft <NUM>.

The blade coupler <NUM> may also be configured in different ways in order to allow different speed rotation of the blades. For example, the blade coupler <NUM> may be embodied as or include a gearbox having individual brackets for supporting each of the first and second blades <NUM> and <NUM>, respectively. The brackets may then be operably coupled to the shaft <NUM> via respective gear sets that may be configured to turn the respective ones of the first and second blades <NUM> and <NUM> at corresponding same or different speeds from each other and with respect to the shaft <NUM>. Moreover, the first and second blades <NUM> and <NUM> could also be configured via the respective gear sets to turn in different directions.

Accordingly, a lawn mower of an example embodiment may include a blade housing configured to house at least a first blade and a second blade, a shaft disposed to rotate within the blade housing, a powerhead configured to selectively turn the shaft responsive to application of power from a power source (e.g., a battery or gas/petrol engine), and a blade coupler configured to selectively couple the first blade and/or the second blade to the shaft to produce different cutting performance conditions based on which of the first blade and/or the second blade is operably coupled to the shaft.

Claim 1:
A power management assembly for controlling rotation of blades (<NUM>, <NUM>) responsive to operation of a powerhead (<NUM>) of a lawn mower (<NUM>), the power management assembly comprising:
a first blade (<NUM>) disposed within a blade housing (<NUM>) and selectively operably coupled to a shaft (<NUM>);
a second blade (<NUM>) disposed within the blade housing (<NUM>) and selectively operably coupled to the shaft (<NUM>); and
a blade coupler (<NUM>) configured to selectively couple the first blade and/or the second blade to the shaft to produce different cutting performance conditions based on which of the first blade and/or the second blade is operably coupled to the shaft,
wherein the first blade (<NUM>) and the second blade (<NUM>) are each of a different type in terms of energy consumption or cutting characteristics, and
wherein the blade coupler is configured to be movable vertically to selectively engage the first blade and the second blade alone or in combination with each other.