WO2025012685A1

WO2025012685A1 - Collector level measurement and blade speed control

Info

Publication number: WO2025012685A1
Application number: PCT/IB2023/057158
Authority: WO
Inventors: Michael Schmid; Rupert Stelzer
Original assignee: Husqvarna AB
Current assignee: Husqvarna AB
Priority date: 2023-07-12
Filing date: 2023-07-12
Publication date: 2025-01-16
Anticipated expiration: 2026-01-12

Abstract

A lawn mower (10) may include a blade housing (12) configured to house at least one blade (14), an electric motor (18) operably coupled to and configured to selectively rotate the at least one blade (14), a mobility assembly (25) operably coupled to the blade housing (12) to enable movement of the lawn mower (10), a collector (30) operably coupled to the blade housing (12) and configured to receive grass clippings or debris ejected from the blade housing (12) responsive to airflow generated by rotation of the at least one blade (14), a sensor (60) configured to determine fill level information of the collector (30), and a controller (70) configured to control blade speed for the at least one blade (14) based on the fill level information.

Description

COLLECTOR LEVEL MEASUREMENT AND BLADE SPEED CONTROL

TECHNICAL FIELD

Example embodiments generally relate to outdoor power equipment and, more particularly, relate to a lawn mower having a grass collector that is configured to measure a level of the contents of the grass collector and perform a function based on the results of the measurement.

BACKGROUND

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. Meanwhile, at the other end of the spectrum, riding lawn mowers, such as lawn tractors, can be quite large. Riding lawn mowers can sometimes also be configured with various functional accessories (e.g., trailers, tillers and/or the like) in addition to grass cutting components. Riding lawn mowers can also be ruggedly built and have sufficient power, traction, and handling capabilities to enable operators to mow over rough terrain, if needed. Recently, robotic lawn mowers are also increasing in popularity.

Regardless of the specific type of lawn mower, some lawn mowers may include a grass collector into which grass clippings (or other yard debris) can be collected. When the grass collector is full, the operator needs to empty it to make room for continued effective operation of the lawn mower. Various indicators may be employed to inform the operator that the grass collector is full. However, there is generally no other fill level indication that is useful for anything other than letting the operator know that it is time to empty the grass collector. Meanwhile, such information could potentially be put to profitable use.

Accordingly, it may be desirable to develop improved ways to monitor and use information regarding the fill level of a grass collector.

BRIEF SUMMARY OF SOME EXAMPLES

Some example embodiments may therefore provide for improved lawn mower design by providing a fill level of the collector that can be determined and displayed or used to control blade speed. Some example embodiments may provide for improving the operator experience relative to the ease of use and convenience associated with maximizing the amount of cutting that can be done by the lawn mower on a single battery charge.

In an example embodiment, a lawn mower may be provided. The lawn mower may include a blade housing configured to house at least one blade, an electric motor operably coupled to and configured to selectively rotate the at least one blade, a mobility assembly operably coupled to the blade housing to enable movement of the lawn mower, a collector operably coupled to the blade housing and configured to receive grass clippings or debris ejected from the blade housing responsive to airflow generated by rotation of the at least one blade, a sensor configured to determine fill level information of the collector, and a controller configured to control blade speed for the at least one blade based on the fill level information.

In still another example embodiment, a lawn mower is provided. The lawn mower may include a blade housing configured to house at least one blade, an electric motor operably coupled to and configured to selectively rotate the at least one blade, a mower housing inside which the electric motor is housed, a mobility assembly operably coupled to the blade housing and/or the mower housing to enable movement of the lawn mower, a collector operably coupled to the blade housing and configured to receive grass clippings or debris ejected from the blade housing responsive to airflow generated by rotation of the at least one blade, a time of flight sensor configured to determine fill level information of the collector, and a controller configured to drive a display of the fill level information at a user interface provided at a portion of the mower housing.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:

FIG. 1 illustrates a side view of a walk-behind lawn mower according to an example embodiment;

FIG. 2 illustrates a rear view of a portion of the walk-behind lawn mower to illustrate components of a time of flight sensor according to an example embodiment;

FIG. 3 illustrates a block diagram of blade speed control system according to an example embodiment; and

FIG. 4 illustrates a block diagram of a blade speed determination algorithm in accordance with an example embodiment. DETAILED DESCRIPTION

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. Like reference numerals refer to like elements throughout. 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. 1 illustrates a side view of a lawn mower 10 of an example embodiment in the form of a walk-behind lawn mower. However, it should be appreciated that the lawn mower 10 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 mower, or any other device employing a collector such as a grass collector.

For lawn mower 10 depicted, an operator may be located at an operator station behind the lawn mower 10. The lawn mower 10 of FIG. 1 includes a blade housing 12 that may house a rotatable cutting blade 14 (not visible, and therefore represented in block form). The cutting blade 14 may be suspended above the ground at the end of a rotatable shaft 16 (also shown in block form FIG. 1) that may be turned responsive to operation of an electric motor 18 powered by a battery 20 (or other electrical power source). Operation of the electric motor 18 may be initiated by actuation of a key, button, switch or other similar device by the operator.

In an example embodiment, the electric motor 18 and the battery 20 may be provided within a mower housing 22 that generally provides a body inside which internal components of the lawn mower 10 can be protected and housed. The mower housing 22 may also provide an aesthetically appealing or unique branded appearance that may be selected by the manufacturer. Although the mower housing 22 may be a single unitary structure in some cases, in others, the mower housing 22 may include separate structures or compartments for various different components of the lawn mower 10. Thus, for example, the battery 20 and the electric motor 18 may be housed within the same or separate compartments of the mower housing 22. In some embodiments, the mower housing 22 may sit atop, or otherwise generally be positioned above the blade housing 12 or at least a portion thereof.

The lawn mower 10 may include a mobility assembly on which a substantial portion of the weight of the lawn mower 10 may rest when the lawn mower 10 is stationary. The mobility assembly may also provide for movement of the lawn mower 10. In some cases, the mobility assembly may be driven via power from the electric motor 18 that may be selectively provided to ground engaging wheels 25, which make up the mobility assembly. The mower housing 22 may therefore be supported by the ground engaging wheels 25.

In some examples, the ground engaging wheels 25 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.

Rotation of the cutting blade 14 (e.g., in a plane substantially parallel to the ground) may generate grass clippings, and/or other debris that may be ejected from the blade housing 12 responsive to the airflow that is also generated within the blade housing 12. In some cases, the clippings/debris may be ejected from a side or rear of the blade housing 12. When a rear discharge is employed, many such lawn mowers may employ a collector 30 to collect discharged clippings/debris. However, collectors may also be used for side discharge models in some cases. The collector 30 may be removable to enable the operator to empty the collector 30, and the collector 30 may be made of fabric, plastic or other suitable materials. In an example embodiment, a rear door 32 may be provided to mate with the collector 30 when the lawn mower 10 is ready to cut grass with the collector 30 attached, and to at least partially close off the rear of the blade housing 12 for operation without the collector 30.

The door 32 may be hingedly attached to a handle bracket assembly, a housing inside which the battery 20 and the electric motor 18 are housed and/or the blade housing 12 above and proximate to the rear discharge in order to drop down and at least partially cover the rear discharge if the collector 30 is removed for any reason. The collector 30 may interface with the blade housing 12 at the rear discharge and the door 32 to provide a relatively tight seal so that the clippings ejected through the rear discharge are captured in the collector 30. As such, the door 32 may extend over at least a portion of the collector 30. The door 32 may, in some cases, be biased toward engagement with the blade housing 12 (e.g., to cover the rear discharge) by a biasing member (e.g., a spring). The biasing member, if provided, may urge the door 32 to rotate toward the rear discharge and/or the blade housing 12 by pivoting the door 32 about a pivot axis.

In an example embodiment, the lawn mower 10 may further include a handle assembly. The handle assembly of FIG. 1 may include one or more handle members 40 (only one of which is visible in the side view of FIG. 1) that extend generally rearward and upward from a rear portion of the blade housing 12. In many cases, the handle assembly may include two instances of the handle members 40 extending rearward and upward from opposing sides of a rear portion of the blade housing 12 (e.g., proximate rear ones of the ground engaging wheels 25). In such examples, the handle members 40 may be substantially parallel to each other and may be connected to each other at their distal ends via a cross bar that may form an additional portion of the handle assembly. A proximal end 44 of the handle members 40 may engage or otherwise be operably coupled to the lawn mower 10 (e.g., to the blade housing 12 or to a handle bracket assembly that is operably coupled to the blade housing 12). Meanwhile, a distal end 46 of the handle members 40 may typically be grasped by the operator to control the lawn mower 10 (e.g., by pushing the handle members 40) during operation. Thus, the terms distal and proximal should be understood to be used in reference to the blade housing 12 or electric motor 18 of the lawn mower 10.

The handle members 40 may be adjustable in height or may be foldable to reduce the amount of space that the lawn mower 10 consumes when stored or shipped via operation of a handle adjustment assembly. The handle adjustment assembly may take many forms, but typically provides a pivot point about which the handle assembly is enabled to rotate based on operator adjustment. In some cases, the handle adjustment assembly may enable the handle assembly to be selectively rotated to a folded position, to a vertical position, and/or to a number of different operating positions at which the handle assembly may then be fixed.

The collector 30 may be operably coupled to the lawn mower 10 via any of a number of ways. Thus, for example, the collector 30 (or lawn mower 10) may include a connection assembly that is operable to alternately connect or disconnect the collector 30 from the lawn mower 10. The connection assembly may, in some cases, further connect the collector 30 to the handle members 40 so that pivoting of the handle members 40 forward may carry the collector 30 about a pivot point and dump the collector 30. However, in other cases, the operator may simply remove the collector 30 by hand and dump the collector 30, or manually pivot the collector 30 about the pivot point to dump the collector 30. Still other ways of dumping and thereby emptying the collector 30 are also possible, and are generally outside the scope of this invention. Because dumping of the collector 30 may be necessary to ensure continued effective collection of grass clippings or debris once the collector 30 is full, knowledge of the fact that the collector 30 is full is of great utility, if not necessity. However, there may also be utility in knowing the degree to which the collector 30 is full (i.e., the fill level of the collector 30). For example, the operator may get a sense for how much cutting can be accomplished before the next time the collector 30 will need to be dumped or emptied. That said, beyond any value in simply knowing the fill level of the collector 30, such information may, in some cases, be put to greater use by implementing one or more control functions as described in greater detail below.

Once obtained, the knowledge of the fill level of the collector 30 may be communicated to the operator via a user interface 50. The user interface 50 may be provided at a portion of the mower housing 22 in some cases, and may take the form of a gauge, light(s), display and/or the like. Thus, for example, the user interface 50 may be a single discrete fill level indicator provided at a top portion of the mower housing 22 to be apparent and visible to the operator while the operator operates the lawn mower 10. However, the user interface 50 may be distributed, or may have distributed elements, in some cases. Moreover, whether a single discrete component or distributed, the user interface 50 could be provided at other locations. For example, a display element 52 may be provided at the distal end 46 of one or both of the handle members 40 (e.g., at the cross bar therebetween).

In order to obtain the knowledge of the fill level of the collector 30, particularly in a way that is useful to drive other electronic functions, and that is dynamic in terms of being able to monitor and track changes to the fill level of the collector 30 in real time, a dynamic sensor may be required. The dynamic sensor may be positioned in or proximate to the collector 30 in such a way as to enable the dynamic sensor to monitor and report on the fill level during operation of the lawn mower 10. An example of such a dynamic sensor is shown in FIG. 1 as time-of-flight (TOF) sensor 60.

By using the TOF sensor 60, the fill level of the collector 30 may be monitored during operation of the lawn mower 10. Providing such information to the user interface 50 may make it available to the operator during operation of the lawn mower 10 as well, to enable the operator to dump the collector 30 when appropriate. However, usage of that information to perform additional functions may require an additional actor capable to implementing various control functions for the lawn mower 10. In an example embodiment, the lawn mower 10 may include a controller 70, which may be configured to receive fill level information from the TOF sensor 60 and utilize the fill level information to perform other control functions for the lawn mower 10 as described in greater detail below.

In an example embodiment, the controller 70 may be operably coupled to the TOF sensor 60 to receive the fill level information. The operable coupling may typically be provided by wired connection of the TOF sensor 60 to the controller 70. However, in some cases, the controller 70 and the TOF sensor 60 could be connected by wireless communication means. The controller 70 may in turn also be operable coupled (e.g., by wired or wireless connection) to the user interface 50 and/or the display element 52 to drive updated information display of the fill level information at the user interface 50 and/or the display element 52. However, it is also possible to drive the user interface 50 and/or the display element 52 directly from the TOF sensor 60 and without the controller 70 being in the communication path therebetween.

In some examples, the controller 70 may be configured to further control a blade speed of the cutting blade 14 based on the fill level information. In particular, as fill level of the collector 30 increases (at least above a threshold value), blade speed of the cutting blade 14 may be decreased. The control of blade speed of the cutting blade 14 may be accomplished by the controller 70 controlling the operation of the electric motor 18. Thus, for example, the controller 70 may be configured to provide control of the operating speed of the electric motor 18, and therefore also control the rotation of the rotatable shaft 16 and blade speed of the cutting blade 14.

Conventional controllers also often control blade speed. However, such control in conventional controllers is normally employed to make the blade speeds for the cutting blade 14 consistent and relatively fixed at either one standard operating speed, or a selected specific speed (e.g., manually selectable hi and low settings). There is generally no dynamic control of the blade speed that is performed in conventional contexts. Although some slowing may be experienced due to resistance (e.g., from cutting wet or thick grass), or due to loss of power via discharge of the battery 20, these slowing phenomena are generally undesirable, not intentional, and therefore not caused by the motor controllers employed. However, the controller 70 of example embodiments may take active measures to slow the blade speed of the cutting blade 14 in order to enhance operational efficiency of the lawn mower 10 by extending the cutting time that can be achieved in a single charge cycle for the battery 20. In this regard, if the battery 20 operates the electric motor 18 at a lower speed, the battery 20 generally can enable the electric motor 18 to operate for a longer period of time. More cutting can therefore be accomplished on a single charge cycle for the battery 20, and operator satisfaction is generally increased. For example, slowing blade speed from 3000 rpm to 1500 rpm (based on the product of momentum, cutting speed and two times pi) could save as much as 50% of the energy used during one operational cycle of the battery 20 on a single full charge.

Notably, one may assume from the discussion above that it might simply be better to operate the electric motor 18 at the lower speed all the time to extend battery life between charge cycles. However, doing so as a general premise is not advisable since cutting and collecting efficiency may be negatively impacted. Thus, the controller 70 is actually configured to intelligently control the blade speed of the cutting blade 14 to make sure that cutting efficiency is maximized while also extending battery life when possible. As such, a simple and unstructured or uncontrolled reducing of the blade speed of the cutting blade 14 is not desirable, but controlling the reduction of the blade speed of the cutting blade 14 based on the fill level information may not reduce cutting efficiency for reasons explained below.

In this regard, it should be appreciated that grass can actually be cut effectively at a relatively low blade speed. Whereas a common operating blade speed may be about 3500 rpm, the grass may still be cut effectively at a blade speed of about 2600 rpm (or perhaps even lower in some cases all the way down to 1500 rpm). However, the higher blade speed (e.g., 3500 rpm) is typically required to drive sufficient airflow within the blade housing 12 to eject the grass clippings (or debris) out of the blade housing 12 and into the collector 30. In particular, the larger the size of the collector 30, the more airflow will be required to effectively eject the grass clippings to reach the back of the collector 30 to fully or evenly fill the collector 30 during operation. That said, as the collector 30 begins to fill up, the remaining empty space is reduced and the effective size of the collector 30 is consequently also reduced. This effective size reduction means that the airflow needed to fill the remaining and reducing space continues to also decline. With the reducing airflow requirement as the collector 30 fills, the knowledge of the fill level of the collector 30 may be provided to the controller 70 so that the controller 70 can intelligently reduce blade speed and airflow to continue to effectively cut grass and fill the collector 30, but do so at lower blade speeds that will extend the operating capacity of the electric motor 18 on a single charge cycle of the battery 20.

To enhance the accuracy and utility of the TOF sensor 60, the placement of the TOF sensor 60 relative to the collector 30 may be strategically selected. In this regard, for example, the TOF sensor 60 may be located proximate to the pivot axis of the door 32, and therefore near the top portion of the collector 30. Moreover, the TOF sensor 60 may be oriented to transmit signals for which to time taken for travel to and reflection off a top surface of the mass of grass clippings or debris in the collector 30 and return to the TOF sensor 60 may be measured in order to determine the fill level information. In this regard, a transmit signal 80 is shown in FIG. 1 extending all the way to the back corner of the collector 30 when the collector 30 is empty, and then reflected signal 82 returns to the TOF sensor 60 to define a total time of flight that will be consistent whenever the collector 30 is empty. However, if the collector 30 is instead filled to fill level 84 shown in FIG. 1, which is about 1/2 full, the time of flight of the transmit signal 80 and the reflected signal 82 in the round trip from and back to the TOF sensor 60 may be about 1/2 as long. The TOF sensor 60 (or the controller 70) may be able to therefore accurately determine the fill level information (e.g., as a percentage or fraction of the total capacity of the collector 30 that is currently filled) based on the time of flight measurements made at any given time. In this regard, each measured time of flight may correspond to a respective fill level for the collector 30. The fill level determined based on the time of flight measured may then be indicated at the user interface 50 and/or the display element 52.

In some embodiments, the user interface 50 may employ light indicators that include LEDs or LED backlit images that are lit or unlit to indicate corresponding status information. The information indicated by the light indicators may be directly related to the corresponding fill level in some cases. However, in other cases, some of the light indicators may further indicate status information associated with speed of the cutting blade 14. In still other cases, the user interface 50 may be remotely located from the lawn mower 10. Thus, for example, the user interface 50 may be located at a terminal or cell phone that is remotely located and communicatively coupled to the lawn mower 10 wirelessly. Thus, it may be possible to monitor blade speed remotely for fleet management of battery consumption and planned recharging and replacement.

FIG. 2 shows a back view of the portion of the lawn mower 10 that lies under the door 32. In this regard, FIG. 2 shows a collector interface 100 portion of the lawn mower 10 that is exposed by lifting the door 32, and that forms part of the surface that interfaces with or contacts the collector 30 when installed. The collector interface 100 may include a rear wall 110, which may face the collector 30 and actually form a boundary (or partial boundary) of the containment volume formed by the collector 30 when the collector 30 is installed. An ejection port 120 may be formed in the rear wall 110 and may be operably coupled to the volume of the blade housing 12 inside which the cutting blade 14 rotates. The rotation of the cutting blade 14 within the volume of the blade housing 12 may generate airflow out of the blade housing 12 and into the collector 30 via the ejection port 120. The airflow may carry grass clippings or debris through the ejection port 120 and into the collector 30.

Meanwhile, the TOF sensor 60 of FIG. 1 may include a transmitter 130 and receiver 140. The transmitter 130 may transmit a signal (e.g., transmit signal 80) into the collector 30 to be reflected off a top of the debris or other contents of the collector 30. The signal then reflected (e.g., the reflected signal 82) may return to the TOF sensor 60 and be detected by the receiver 140 with the total round trip time from transmission to reception being measured as the time of flight. To maximize the accuracy of the TOF sensor 60, it may be desirable to measure the longest possible time of flight for each corresponding fill level. To accomplish this, the transmitter 130 and receiver 140 may not be oriented to look straight down (i.e., from the top of the collector 30 directly down below to the bottom of the collector 30), which would be the most intuitive approach. Instead, the transmitter 130 and receiver 140 may be positioned on the rear wall 110 and oriented to look from a top front portion of the collector 30 to a rear bottom portion of the collector 30. Thus, the transmitter 130 and receiver 140 may be disposed proximate to each other at a top portion of the rear wall 110, which may be also about equal to (or at a same elevation as) a top boundary or top wall 150 of the ejection port 120.

The time of flight could be directly converted to a fill level of the collector 30, or may be used to determine a distance to the top of the mass of grass clippings or debris in the collector relative to the transmitter 130 and receiver 140. The ability to accurately measure and distinguish the distance is also enhanced by enabling a larger range of distances to be measured, which is accomplished by the angled arrangement of the transmitter 130 and receiver 140 as described above.

FIG. 3 illustrates a functional block diagram for explaining the operation of a blade speed control system 200 incorporating the TOF sensor 60 of an example embodiment. As shown in FIG. 3, the blade speed control system 200 may include the TOF sensor 60 providing time of flight information 210 to the controller 70. The controller 70 may include processing circuitry 220 (e.g., a processor and memory) to control operation of the electric motor 18 of the lawn mower 10 according to an example embodiment as described herein. In this regard, for example, the controller 70 may utilize the processing circuitry 220 to determine the fill level of the collector 30 based on the time of flight information 210.

The TOF sensor 60 may employ RF signals (e.g. radar) or ultrasonic signals in some cases. When employing ultrasonic signals, the TOF sensor 60 may employ signals that are less than 100 KHz, and in some cases in a range of between 40-45 KHz due to the low cost and readily available nature of sensors manufactured to operate in that range. When the reflected signal 82 is received by the TOF sensor 60, the time of flight information 210 may be provided to the controller 70 to enable the processing circuitry 220 to provide electronic control inputs to one or more functional units of the system 200, as described herein.

The processing circuitry 220 may therefore be configured to perform data processing, control function execution, and/or other processing and management services according to an example embodiment of the present invention. In some embodiments, the processing circuitry 220 may be embodied as a chip or chip set. In other words, the processing circuitry 220 may comprise one or more physical packages (e.g., chips) including materials, components, and/or wires on a structural assembly (e.g., a baseboard). The structural assembly may provide physical strength, conservation of size, and/or limitation of electrical interaction for component circuitry included thereon. The processing circuitry 220 may therefore, in some cases, be configured to implement an embodiment of the present invention on a single chip or as a single “system on a chip.” As such, in some cases, a chip or chipset may constitute means for performing one or more operations for providing the functionalities described herein.

In an example embodiment, the processing circuitry 220 may employ functional modules that are configured to perform various aspects of the activities discussed herein. Thus, for example, the processing circuitry 220 may include a fill level determiner 230 that may be configured to determine a fill level of the collector (i.e., fill level information) based on the time of flight information 210. In some embodiments, the fill level determiner 230 may include a lookup table or employ other calculational means to determine the fill level information based on the time of flight information 210. The fill level determiner 230 may use the fill level information to drive an output indicating the same at the user interface 50 and/or the display element 52.

The processing circuitry 220 may also include a blade speed determiner 240 that may be configured to control the electric motor 18 to thereby also control rotational speed of the cutting blade 14. In some embodiments, the blade speed determiner 240 may employ a lookup table to correlate the fill level information to corresponding blade speed settings. Alternatively or additionally, the blade speed determiner 240 may execute a blade speed determination algorithm that may use fill level information as an input and cycle through various determining stages to determine a speed for driving the electric motor 18 and thereby also the cutting blade 14 at the determined speed. FIG. 4 illustrates a block diagram showing an example of such an algorithm in accordance with an example embodiment. In this regard, as shown in FIG. 4, the algorithm may start at operation 400 as part of a cycle of operations (or multiple cycles) that can be used to control blade speed. Operation 405 may be used along with operation 420 to determine proper operation of the TOF sensor 60. More particularly, a minimum error threshold may be set to indicate a value too small to be valid, and therefore indicative of an error, and a maximum error threshold may be set to indicate a value too large to be valid. Thus, for example, operation 405 may include determining whether the distance measured (or fill level) is indicative of a distance that is too small to occur with proper operation of the TOF sensor 60. If the distance measured is too small (or the fill level too high), then at operation 410 the standard speed (e.g., 3500 rpm) may be set along with setting an error indicator at the user interface 50 or the display element 52. The cycle will also then be terminated with the setting of the error indicator at operation 415.

If instead, the distance measured is above the minimum error threshold, it may also be determined as to whether the distance measured is larger than the maximum error threshold at operation 420. This would signify a measurement that is larger than the collector 30 itself, which should not be possible. If the distance measured is too large, then at operation 425 the standard speed (e.g., 3500 rpm) may be set along with setting an error indicator at the user interface 50 or the display element 52. The cycle will also then be terminated with the setting of the error indicator at operation 415 as above.

Assuming the distance measured is neither too high nor too low, then the distance measured may be compared to a first level threshold at operation 430. The first level threshold may be a fixed percentage of fill of the collector (e.g., 1/3, 1/2 or 2/3), and may represent a fill level at which the impact on airflow requirements is not significant enough to see an appreciable advantage from an incremental reduction in the blade speed. Thus, if at operation 430 the distance is greater than the first level threshold, then the standard speed (e.g., 3500 rpm) may be set at operation 435 and process flow may return to operation 400. However, once the first level threshold is exceeded a determination may thereafter be made as to whether the distance measured is reduced below a second level threshold at operation 440. If the distance measured is less than the second level threshold, then it should be appreciated that there may be sufficient filling of the collector 30 to render the collector 30 effectively smaller, and allow lower airflow to continue to efficiently fill the collector 30. As such, the second level threshold may represent a fill level at which the impact on airflow requirements is significant enough to permit an incremental reduction in the blade speed (and airflow) without suffering any penalty on cutting or the efficiency of filling the collector 30. Accordingly, if the distance measured is less than the second level threshold at operation 440, then a first incremental blade speed reduction may be introduced relative to the standard speed at operation 445 and process flow may return to operation 400. If the distance measured is not less than the second threshold then continued monitoring may be conducted to determine whether the distance measured is less than a third level threshold at operation 450. Distance measured being less than the third level threshold would signify that further filling of the collector 30 has rendered it again effectively smaller and permit further airflow reduction. Thus, if the distance measured is less than the third level threshold at operation 440, then a second incremental blade speed reduction may be introduced relative to the standard speed at operation 455 and process flow may return to operation 400.

The processes of operations 440, 445, 450 and 455 may be repeated in operations 460 and 465 for a measured distance of less than a fourth level threshold with potential reduction of blade speed by a third increment from the standard speed, and at operations 470 and 475 for distance less than an nth level threshold with potential reduction of blade speed by a n-lth increment from the standard speed. In some cases, where the standard speed is 3500 rpm, the first, second, third, fourth and n-lth incremental reductions in speed may each be the same, and may be about 150 rpm each. However, the increments could be different, and may either increase or decrease with each step in some alternative embodiments. In each case, after an incremental blade speed reduction is implemented, the control flow may return to operation 400 to enable cyclic monitoring to occur.

The distance level thresholds may depend upon the overall size of the collector 30. As one example, if the collector 30 is sized such that the minimum error threshold is 80 mm and the maximum error threshold is 1000 mm, the first distance threshold may be about 350 mm (or about 35% of the maximum error threshold). The distance thresholds thereafter may increase by 10 mm, 20 mm, 30 mm or 40 mm and they may be consistent for each step, may increase, or may decrease for each step. In one example, the second distance threshold may be 340 mm, the third distance threshold may be 280 mm, the fourth distance threshold may be 240 mm, and subsequent thresholds may increase, decrease, or stay the same with each step. In some cases, the lowest threshold employed for a corresponding slowest speed of 2600 rpm may be about 150 mm.

The cyclic monitoring mentioned above, and performed by the processing circuitry 220 of the controller 70, may be performed at any suitable interval, or even continuously. Thus, for example, in some cases, the TOF sensor 60 may continuously measure the time of flight information 210 and provide the same to the controller 70. In such cases, the controller 70 may be configured to also continuously determine fill level information to control blade speed (based on the incremental thresholds defined by the blade speed determination algorithm) and drive the user interface 50 and/or display element 52 accordingly. However, if even power consumption of the TOF sensor 60 and/or controller 70 is desired, the controller 70 may be configured to control operation of the TOF sensor 60 to turn it on for periodic measurement. The periodicity may be constant in some cases. However, in other cases, the periodicity may be lower for larger measured distance (i.e., emptier conditions in the collector 30) and may the periodicity may increase (i.e., making the time between measurements shorter) as the measured distances decrease to indicate that the collector 30 is filling up.

Accordingly, a lawn mower of an example embodiment may be provided. The lawn mower may include a blade housing configured to house at least one blade, an electric motor operably coupled to and configured to selectively rotate the at least one blade, a mobility assembly operably coupled to the blade housing to enable movement of the lawn mower, a collector operably coupled to the blade housing and configured to receive grass clippings or debris ejected from the blade housing responsive to airflow generated by rotation of the at least one blade, a time of flight sensor configured to determine fill level information of the collector, and a controller configured to control blade speed for the at least one blade based on the fill level information. Alternatively or additionally, the controller may drive a display of the fill level information at a user interface.

In some embodiments, the features described above may be augmented or modified, or additional features may be added. These augmentations, modifications and additions may be optional and may be provided in any combination. Thus, although some example modifications, augmentations and additions are listed below, it should be appreciated that any of the modifications, augmentations and additions could be implemented individually or in combination with one or more, or even all of the other modifications, augmentations and additions that are listed. As such, for example, the mower may further include a mower housing inside which the electric motor is housed. The user interface may be provided at a portion of the mower housing, and the controller may drive a display of the fill level information at the user interface. In an example embodiment, the mower may further a handle assembly including a display element at a portion of the handle assembly. The controller may drive a display of the fill level information at the display element. In some cases, the mower may further include a door operably coupled thereto in order to partially block an ejection port from the blade housing when the collector is removed, and to cover an opening in the collector when the collector is installed. The time of flight sensor may include a transmitter and receiver disposed proximate to a top of the ejection port. In an example embodiment, the transmitter and receiver transmit and receive radar waves. In some embodiments, the time of flight sensor may be embodied as an ultrasonic sensor, which may in some cases operate in a frequency range of about 40 KHz to about 45 KHz. In an example embodiment, the controller may set the blade speed at a standard speed for the at least one blade responsive to the fill level information indicating the collector being filled less than a first threshold. In some embodiments, responsive to the collector being filled greater than the first threshold, the controller cyclically monitors the fill level information to determine when the collector is filled greater than a second threshold, a third threshold and an nth threshold. Thereafter, responsive to the fill level information indicating that the collector is filled greater than the second threshold, the blade speed of the at least one blade may be reduced by a first increment, responsive to the fill level information indicating that the collector is filled greater than the third threshold, the blade speed of the at least one blade may be reduced by a second increment, and responsive to the fill level information indicating that the collector is filled greater than the nth threshold, the blade speed of the at least one blade may be reduced by an n-lth increment. In an example embodiment, the collector may controls a periodicity of determining the fill level information based on a degree to which the collector is filled.

Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Moreover, although the foregoing descriptions and the associated drawings describe exemplary embodiments in the context of certain exemplary combinations of elements and/or functions, it should be appreciated that different combinations of elements and/or functions may be provided by alternative embodiments without departing from the scope of the appended claims. In this regard, for example, different combinations of elements and/or functions than those explicitly described above are also contemplated as may be set forth in some of the appended claims. In cases where advantages, benefits or solutions to problems are described herein, it should be appreciated that such advantages, benefits and/or solutions may be applicable to some example embodiments, but not necessarily all example embodiments. Thus, any advantages, benefits or solutions described herein should not be thought of as being critical, required or essential to all embodiments or to that which is claimed herein. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

THAT WHICH IS CLAIMED:

1. A lawn mower (10) comprising: a blade housing (12) configured to house at least one blade (14); an electric motor (18) operably coupled to and configured to selectively rotate the at least one blade (14); a mobility assembly (25) operably coupled to the blade housing (12) to enable movement of the lawn mower (10); a collector (30) operably coupled to the blade housing (12) and configured to receive grass clippings or debris ejected from the blade housing (12) responsive to airflow generated by rotation of the at least one blade (14); a sensor (60) configured to determine fill level information of the collector (30); and a controller (70) configured to control blade speed for the at least one blade (14) based on the fill level information.

2. The lawn mower (10) of claim 1, further comprising a mower housing (22) inside which the electric motor (18) is housed, wherein a user interface (50) is provided at a portion of the mower housing (22), and wherein the controller (70) drives a display of the fill level information at the user interface (50).

3. The lawn mower (10) of claim 1, further comprising a handle assembly (40) including a display element (52) at a portion of the handle assembly (40), wherein the controller (70) drives a display of the fill level information at the display element (52).

4. The lawn mower (10) of claim 1, further comprising a door operably coupled to the lawn mower (10) to partially block an ejection port (120) when the collector (30) is removed, and to cover an opening in the collector (30) when the collector (30) is installed, wherein the sensor (60) comprises a transmitter (130) and receiver (140) disposed proximate to a top of the ejection port (120).

5. The lawn mower (10) of claim 4, wherein the transmitter (130) and receiver (140) transmit and receive radar waves.

6. The lawn mower (10) of claim 4, wherein the sensor (60) comprises an ultrasonic time of flight sensor.

7. The lawn mower (10) of claim 6, wherein the ultrasonic sensor operates in a frequency range of about 40 KHz to about 45 KHz.

8. The lawn mower (10) of claim 1, wherein the controller (70) sets the blade speed at a standard speed for the at least one blade (14) responsive to the fill level information indicating the collector (30) is filled less than a first threshold.

9. The lawn mower (10) of claim 8, wherein responsive to the collector (30) being filled greater than the first threshold, the controller (70) cyclically monitors the fill level information to determine when the collector (30) is filled greater than a second threshold, a third threshold and an nth threshold, and wherein responsive to the fill level information indicating that the collector (30) is filled greater than the second threshold, the blade speed of the at least one blade (14) is reduced by a first increment, responsive to the fill level information indicating that the collector (30) is filled greater than the third threshold, the blade speed of the at least one blade (14) is reduced by a second increment, and responsive to the fill level information indicating that the collector (30) is filled greater than the nth threshold, the blade speed of the at least one blade (14) is reduced by an n-lth increment.

10. The lawn mower (10) of claim 1, wherein the controller (70) controls a periodicity of determining the fill level information based on a degree to which the collector (30) is filled.

11. A lawn mower (10) comprising: a blade housing (12) configured to house at least one blade (14); an electric motor (18) operably coupled to and configured to selectively rotate the at least one blade (14); a mower housing (22) inside which the electric motor (18) is housed; a mobility assembly (25) operably coupled to the blade housing (12) and/or the mower housing (22) to enable movement of the lawn mower (10); a collector (30) operably coupled to the blade housing (12) and configured to receive grass clippings or debris ejected from the blade housing (12) responsive to airflow generated by rotation of the at least one blade (14); a time of flight sensor (60) configured to determine fill level information of the collector (30); and a controller (70) configured to drive a display of the fill level information at a user interface (50) provided at a portion of the mower housing (22).

12. The lawn mower (10) of claim 11, further comprising a handle assembly (40) including a display element (52) at a portion of the handle assembly (40), wherein the controller (70) drives a display of the fill level information at the display element (52).

13. The lawn mower (10) of claim 11, wherein the controller (70) is configured to control blade speed for the at least one blade (14) based on the fill level information.

14. The lawn mower (10) of claim 13, further comprising a door operably coupled to the lawn mower (10) to partially block an ejection port (120) when the collector (30) is removed, and to cover an opening in the collector (30) when the collector (30) is installed, wherein the time of flight sensor (60) comprises a transmitter (130) and receiver (140) disposed proximate to a top of the ejection port (120).

15. The lawn mower (10) of claim 14, wherein the transmitter (130) and receiver (140) transmit and receive radar waves.

16. The lawn mower (10) of claim 14, wherein the time of flight sensor (60) comprises an ultrasonic sensor.

17. The lawn mower (10) of claim 16, wherein the ultrasonic sensor operates in a frequency range of about 40 KHz to about 45 KHz.

18. The lawn mower (10) of claim 13, wherein the controller (70) sets the blade speed at a standard speed for the at least one blade (14) responsive to the fill level information indicating the collector (30) is filled less than a first threshold.

19. The lawn mower (10) of claim 18, wherein responsive to the collector (30) being filled greater than the first threshold, the controller (70) cyclically monitors the fill level information to determine when the collector (30) is filled greater than a second threshold, a third threshold and an nth threshold, and wherein responsive to the fill level information indicating that the collector (30) is filled greater than the second threshold, the blade speed of the at least one blade (14) is reduced by a first increment, responsive to the fill level information indicating that the collector (30) is filled greater than the third threshold, the blade speed of the at least one blade (14) is reduced by a second increment, and responsive to the fill level information indicating that the collector (30) is filled greater than the nth threshold, the blade speed of the at least one blade (14) is reduced by an n-lth increment.

20. The lawn mower (10) of claim 13, wherein the collector (70) controls a periodicity of determining the fill level information based on a degree to which the collector

(30) is filled.