SE2150016A1

SE2150016A1 - A robotic work tool with enhanced cooling

Info

Publication number: SE2150016A1
Application number: SE2150016A
Authority: SE
Inventors: Willy Olofsson
Original assignee: Husqvarna Ab
Priority date: 2021-01-13
Filing date: 2021-01-13
Publication date: 2022-07-14
Also published as: SE544860C2; DE102021006363A1

Abstract

The present disclosure relates to an outdoor robotic work tool (100) comprising a main body (140), a plurality of wheels (130), at least one environmental detection device (170, 171, 172, 173) and a control unit (110). The main body (140) at least partly covers the environmental detection device, the control unit (110) and at least one motor (150) adapted to drive at least some of the wheels (130). The main body (140) comprises a cooling inlet (180) and a cooling outlet (181), and the outdoor robotic work tool (100) further comprises a separate cooling channel (182, 183, 184) that fluidly connects the cooling inlet (180) and the cooling outlet (181) via the control unit (110). The robotic work tool (100) comprises a cooling fan (185) that is adapted to propel air from the cooling inlet (180) to the cooling outlet (181) via the cooling channel (182, 183, 184) and the control unit (110) such that an air flow (F) that passes the control unit (110) is formed.

Description

TITLE A robotic work tool with enhanced cooling TECHNICAL FIELD The present disclosure relates to outdoor robotic work tools, such as robotic lawnmowers, that are adapted to operate within a certain operation area. Such a roboticwork tool is normally equipped with environmental detection devices and processingcircuitry that need cooling.

BACKGROUND Robotic work tools such as for example robotic lawn mowers are becomingincreasingly more popular. ln a typical deployment a work area, such as a garden, thework area can be enclosed by a boundary wire with the purpose of keeping the roboticlawn mower inside the work area. An electric control signal may be transmitted throughthe boundary wire, thereby generating an (electro-) magnetic field emanating from theboundary wire. The robotic working tool is typically arranged with one or more sensorsadapted to sense the control signal.

Alternatively, or as a supplement, the robotic lawn mower can be equipped with anavigation system that is adapted for satellite navigation by means of GPS (GlobalPositioning System) or some other Global Navigation Satellite System (GNSS) system,for example using Real Time Kinematic (RTK). ln addition to this, the navigation systemcan be adapted for navigation by means of a local base station that can be housed ina charging station and provide a navigation signal that further increases the navigation accuracy.

The robotic lawn mower is normally also equipped with environmental detectiondevices and associated processing circuitry, where such environmental detectiondevices include, but are not limited to, ultrasonic sensors, radar sensors, Lidar sensorsand camera devices. These devices, the navigation system and associated processingcircuitry produce heat and require more or less cooling. ln some cases, a passivecooling with a cooling flange that is directed away from the heat source is sufficient, inother cases an active cooling is required. ln particular, when complexity increases, where for example camera devices andvision processing require a lot of processing power, heat generation in the processingcircuitry also increases, and it is therefore becoming more and more important tocooling down the hardware in the robotic lawn mower. Ambient temperatures of 40°Care not unrealistic for an operating robotic lawn mower and improved cooling techniques are therefore required.

EP2816433 describes a robotic lawn mower with a detection unit and an air guidedevice to guide an air flow in the direction of the detection unit during operation of thelawn mower. A drive motor fan wheel can be used for providing an air flow for coolingof both the engine and the detection unit, alternatively a separate fan wheel can beused for at least partial generation of the air flow.

However, a more controlled and efficient cooling is required as heat generationincreases, in particular in processing circuitry comprised in at least one control unit.

SUMMARY The object of the present disclosure is to provide a robotic work tool with an enhancedcooling arrangement for electronic equipment such as a navigation system andenvironmental detection devices and, in particular, processing circuitry comprised in at least one control unit.

This object is achieved by means of an outdoor robotic work tool adapted for a forwardtravelling direction and comprising a main body, a plurality of wheels, at least oneenvironmental detection device and a control unit. The control unit is at least partlyadapted to process input data from at least one environmental detection device. Themain body at least partly covers the environmental detection device, the control unitand at least one motor adapted to drive at least some of the wheels, and comprises acooling inlet and a cooling outlet. The outdoor robotic work tool further comprises aseparate cooling channel that fluidly connects the cooling inlet and the cooling outletvia the control unit. The robotic work tool comprises a cooling fan that is adapted topropel air from the cooling inlet to the cooling outlet via the cooling channel and thecontrol unit such that an airflow that passes the control unit is formed.

This means that a separate controlled air flow is enabled to pass the control unit suchthat sufficient cooling of the control unit is enabled. Since there is a separate coolingfan that only is dedicated for creating the air flow, no other heat-generating parts suchas any one of the other motors or the battery have to be involved.

According to some aspects, the cooling inlet and the cooling outlet are adapted for anair flow that mainly is directed at an angle to the forward travelling direction.

This way, the cooling inlet and the cooling outlet are positioned at a less exposed position, for example at the sides of the outdoor robotic work tool.

According to some aspects, said environmental detection device is in the form of atleast one of a camera device that faces the fon/vard travelling direction, an ultrasonicsensor, a radar sensor, and a Lidar sensor, where the air flow is adapted to pass via at least one environmental detection device.

This provides additional cooling for said environmental detection device, and in thecase of at least one environmental detection device being constituted by a cameradevice, the air flow can possibly be used for removing moist and debris on the inside of a camera lens.

According to some aspects, the control unit is mounted to said environmental detection device.

A compact unit is then formed and can be handled, mounted, replaced and cooled in a more efficient manner.According to some aspects, the cooling fan is arranged in the cooling channel, andaccording to some further aspects, the cooling fan is arranged upstream the control unit.

This provides a compact and efficient cooling structure.

According to some aspects, the main body comprises at least a major part of the cooling channel.

This way, the manufacture of the cooling channel is streamlined.

According to some aspects, the main body comprises integrally formed coolingchannel walls and a separately attached cooling channel lid.

This way, a practical and efficient manufacture is obtained.

According to some aspects, the main body and a major part of the cooling channel are formed in the same piece of material.

This way, the manufacture of the cooling channel is streamlined.

According to some aspects, the control unit is mounted in thermal connection with acooling ﬂange.

This way, heat dissipation from the control unit is alleviated.

According to some aspects, the air flow is adapted to pass via at least one navigation sensor arrangement.

This provides additional cooling for said navigation sensor arrangement.

BRIEF DESCRIPTION OF THE DRAWINGS The present disclosure will now be described more in detail with reference to theappended drawings, where: Figure 1A shows a perspective side view of a robotic lawn mower; Figure 1B shows a schematic overview of the robotic lawn mower; Figure 2 schematically illustrates a front bottom section view of the robotic lawnmower; Figure 3 shows a schematic perspective bottom view of the robotic lawn mower; Figure 4 shows a schematic cut-open partial side view of a cooling channel that isintegrated into the main body; Figure 5 shows a schematic cut-open partial side view of a cooling channel that isintegrated into the main body and having a separate lid; and Figure 6 shows a schematic top view ofa cooling channel that deviates from a main body outer contour.

DETAILED DESCRIPTION Aspects of the present disclosure will now be described more fully hereinafter withreference to the accompanying drawings. The different devices, systems, computerprograms and methods disclosed herein can, however, be realized in many differentforms and should not be construed as being limited to the aspects set forth herein. Likenumbers in the drawings refer to like elements throughout.

The terminology used herein is for describing aspects of the disclosure only and is notintended to limit the invention. As used herein, the singular forms "a", "an" and "the"are intended to include the plural forms as well, unless the context clearly indicates otherwise. lt should be noted that even though the description given herein will be focused onrobotic lawn mowers, the teachings herein may also be applied to any type of outdoorrobotic work tool, such as for example robotic ball collectors, robotic mine sweepersand robotic farming equipment.

Figure 1A shows a perspective view ofa robotic lawn mower 100 and Figure 1B showsa schematic overview of the robotic lawn mower 100. The robotic lawn mower 100 isadapted for a forward travelling direction D, has a main body 140 and a plurality of wheels 130; in this example the robotic lawn mower 100 has four wheels 130, two frontwheels and two rear wheels. The robotic lawn mower 100 comprises a control unit 110and at least one electric motor 150, where at least some of the wheels 130 are drivablyconnected to at least one electric motor 150. lt should be noted that even if thedescription herein is focused on electric motors, combustion engines may alternativelybe used in combination with an electric motor arrangement. The robotic lawn mower100 may be a multi-chassis type or a mono-chassis type. A multi-chassis typecomprises more than one body parts that are movable with respect to one another. Amono-chassis type comprises only one main body part. ln this example embodiment, the robotic lawnmower 100 is of a mono-chassis type,having a main body part 140. The main body part 140 substantially houses allcomponents of the robotic lawnmower 100.

The robotic lawnmower 100 also comprises a grass cutting device 160, such as arotating blade or a disc 160 with a plurality of separate rotating blades 161 driven by acutter motor 165. The robotic lawnmower 100 also has at least one rechargeableelectric power source such as a battery 155 for providing power to the electric motorarrangement 150 and/or the cutter motor 165.

The battery 155 is arranged to be charged by means of received charging current froma charging station (not shown), received through charging skids 156 or other suitablecharging connectors. lnductive charging without galvanic contact, only by means ofelectric contact, is also conceivable. The battery 155 is generally constituted by arechargeable electric power source 155 that comprises one or more batteries that canbe separately arranged or be arranged in an integrated manner to form a combined battery.

According to some aspects, the robotic lawnmower 100 may further comprise at leastone navigation sensor arrangement 175 in a previously known manner, for examplecomprising a satellite navigation sensor in the form of a GPS (Global PositioningSystem) device or other Global Navigation Satellite System (GNSS) device, accordingto some aspects for example using Real Time Kinematic (RTK).

According to some aspects, the robotic lawn mower 100 further comprises at least oneenvironment detection device 170, 171. ln this example, radar transceivers 170 areprovided and adapted to transmit signals and to receive reflected signals in apreviously well-known manner. To enable this, according to some aspects, eachdetector transceiver 170 comprises a corresponding transmitter arrangement andreceiver arrangement together with other necessary circuitry in a well-known manner.ln this example, the robotic lawn mower 100 further comprises a camera device 171that is adapted to provide images of the environment in front of the robotic lawn mower100.

For this purpose, the control unit 110 is adapted to control the camera device 171 andthe radar transceivers 170, and to control the speed and direction of the robotic lawnmower 100 in dependence of information acquired by means of the of the radar transceivers 170 when the robotic lawn mower 100 is moving.

Generally, the control unit 110 is adapted to at least partly process input data from atleast one environmental detection device 170, 171.

With reference also to Figure 2 and Figure 3, the main body 140 at least partly coversthe environmental detection device, the control unit 110 and the motor, and comprisesa cooling inlet 180 and a cooling outlet 181. According to the present disclosure, theoutdoor robotic lawn mower 100 further comprises a separate cooling channel 182,183, 184 that fluidly connects the cooling inlet 180 and the cooling outlet 181 via thecontrol unit 110. The robotic lawn mower 100 further comprises a cooling fan 185 thatis adapted to propel air from the cooling inlet 180 to the cooling outlet 181 via thecooling channel 182, 183, 184 and the control unit 110 such that an air flow F thatpasses the control unit 110 is formed. The air flow F that is forced by means of thecooling fan 185 is indicated with arrows in Figure 2.

This means that a separate controlled air flow F is enabled to pass the control unit 110such that sufficient cooling of the control unit 110 is enabled. Since there is a separatecooling fan 185 that only is dedicated for creating the air flow F, no other heat-generating parts such as any one of the other motors 150, 165 or the battery 155 haveto be involved. lnvolving one or more of the other motors 150, 165, and cooling of these and possibly also the battery 155 as well, will inevitable result in less efficient coolingand a warmer air flow. Furthermore, irrespective of how the air flow is propelled, anycooling air flow that is used for cooling one or motors and/or the battery will inevitableresult in less efficient cooling and a warmer airflow that thus will provide a less efficientcooling of other components. By means of the present disclosure, these drawbacks are avoided.

According to some aspects, in this context, the cooling channel 182, 183, 184 beingseparate means that the cooling channel is dedicated for conveying a cooling air flow, and is not just formed between other existing parts such as a motor and/or a battery.

According to some aspects, the control unit 110 is mounted in thermal connection witha cooling flange 188, where the air flow F also passes via the cooling flange 188.Having an arrangement with a cooling flange 188 alleviates heat dissipation from thecontrol unit 110. A thermal connection may for example be obtained by a good metal-to-metal contact, and/or by means of an intermediate thermally conducting paste.

According to some aspects, the cooling inlet 180 and the cooling outlet 181 eachcomprises a corresponding filter part 186, 187 that is adapted to prevent that dust anddebris such as grass parts enter the cooling channel 182, 183, 184.

According to some aspects, the cooling inlet 180 and the cooling outlet 181 areadapted for an incoming and outgoing air flow that mainly is directed at an angle ß tothe forward travelling direction D. This is indicated for the cooling inlet 180 in Figure 2.According to some further aspects, the angle ß lies in an interval of 60°-120°.

According to some aspects, said environmental detection device is in the form of acamera device 171 that faces the forward travelling direction D, where the air flow F isadapted to pass via the camera device 171. This provides additional cooling for thecamera device 171, and possibly the air flow F can be used for removing moist and debris on the inside of a camera lens 189.

According to some aspects, said environmental detection device is in the form of atleast one of a camera device 171 that faces the forward travelling direction D, an ultrasonic sensor 172, a radar sensor 170, and a Lidar sensor 173, where the air flowF is adapted to pass via at least one environmental detection device 170, 171, 172,173. The ultrasonic sensor 172 and the Lidar sensor 173 are schematically indicatedwith dashed lines in Figure 1B, indicting optional features.

According to some aspects, the air flow F is adapted to pass via at least one navigation sensor arrangement 175.

According to some further aspects, the control unit 110 is mounted to saidenvironmental detection device 170, 171, 172, 173. A compact unit is then formed andcan be handled, mounted, replaced and cooled in a more efficient manner. Forexample, the cooling flange 188 may then alleviate heat dissipation for both the controlunit 110 and the camera device 171.

According to some aspects, the cooling fan 185 is arranged in the cooling channel 182,183, 184. Preferably, the cooling fan 185 is arranged upstream the control unit 110.The cooling fan 185 is then adapted to push the air flow F towards the control unit 110.

The cooling channels 182, 183, 184 can be formed in many ways, and more or less bepartly integrated with the main body as illustrated in Figure 4 and Figure 5 showing cut-open partial side views of a part of a cooling channel 182. According to some aspects,the main body 140 comprises at least a major part of the cooling channel 182, 183,184.

As shown in Figure 4, the main body 140 and a major part of the cooling channel 182are formed in the same piece of material. As shown in Figure 5, according to someother aspects, the main body 140 comprises integrally formed cooling channel walls190, 191 and a separately attached cooling channel lid 192.

According to some aspects, some or all parts of the cooling channel 182, 183, 184 canbe formed by separate parts that are mounted to the main body 140 or some other partof the robotic lawn mower 100.

As illustrated in Figure 6 that shows a partial top view, the cooling channel 182 canfollow an outer contour of the main body 140, and at least partly deviate from the outercontour of the main body 140. This can be the case irrespective of if the coolingchannel 182 is formed in the same piece of material as the main body 140 or not.

According to some aspects, as illustrated in Figure 2 and Figure 3, the cooling channel182, 183, 184 comprises a first channel part 182, a second channel part 183 and athird channel part 184, where the channel parts 182, 183, 184 are ﬂuidly connected toeach other. The third channel part 184 is an intermediate part that comprises the partsto be cooled such as at least one of the control unit 110, the camera device 171 andthe cooling flange188. The third channel part 184 may also comprise the cooling fan185. For example, the first channel part 182 and the second channel part 183 may beintegrated with the main body 140 as described above, while the third channel part 184can be a replaceable part the is fitted between the first channel part 182 and the secondchannel part 183, ﬂuidly connecting these.

The present disclosure is not limited to the above, but may vary freely within the scopeof the appended claims. For example, in Figure 1B, four radar transceivers 170 areshown, two at a front of the lawn mower 100 and two at the rear of the lawn mower.There can be any number of radar transceivers 170 at any suitable positions. lnsteadof radar transceivers, or as a supplement, there can be other types of sensors eitherstanding alone or in combination with other sensors such as Lidar and ultrasonicsensors. lt is also conceivable that there are no such sensors, but only the cameradevice 171. The camera device 171 can also be omitted and only one or more sensorsaccording to the above being used. Generally, there is at least one environmentdetection device that can be in the form ofa camera device 171 and/or an environment detection sensor such as radar 170, Lidar 173 and ultrasonic sensors 172.

According to some aspects, the air flow F is adapted to pass via one or moreenvironmental detection devices 170, 171, 172, 173.

The present disclosure relates to an active cooling system where an air flow is guidedvia one or more heat-generating objects for maximum cooling effect while the hardware is encapsulated and protected from grass, dirt and insects.

Claims

1. An outdoor robotic work tool (100) adapted for a forward travellingdirection (D) and comprising a main body (140), a plurality of wheels (130), at leastone environmental detection device (170, 171, 172, 173) and a control unit (110) thatat least partly is adapted to process input data from at least one environmentaldetection device (170, 171, 172, 173), the main body (140) at least partly covering theenvironmental detection device, the control unit (110) and at least one motor (150)adapted to drive at least some of the wheels (130), wherein the main body (140)comprises a cooling inlet (180) and a cooling outlet (181), and wherein the outdoorrobotic work tool (100) further comprises a separate cooling channel (182, 183, 184)that fluidly connects the cooling inlet (180) and the cooling outlet (181) via the controlunit (110), where the robotic work tool (100) comprises a cooling fan (185) that isadapted to propel air from the cooling inlet (180) to the cooling outlet (181) via thecooling channel (182, 183, 184) and the control unit (110) such that an airflow (F) thatpasses the control unit (110) is formed.

2. The robotic work tool according to claim 1, wherein the cooling inlet andthe cooling outlet are adapted for an air flow (F) that mainly is directed at an angle (ß)to the forward travelling direction (D).

3. The robotic work tool according to any one of the claims 1 or 2, whereinsaid environmental detection device is in the form of at least one of a camera device(171) that faces the forward travelling direction (D), an ultrasonic sensor (172), a radarsensor (170), and a Lidar sensor (173), where the air flow (F) is adapted to pass via atleast one environmental detection device (170, 171, 172, 173).

4. The robotic work tool according to any one of the previous claims, whereinthe control unit (110) is mounted to said environmental detection device (170, 171,172, 173).

5. The robotic work tool according to any one of the previous claims, whereinthe cooling fan (185) is arranged in the cooling channel (182, 183, 184).

6. The robotic work tool according to claim 5, wherein the cooling fan (185) is arranged upstream the control unit (110).

7. The robotic work tool according to any one of the previous claims, whereinthe main body (140) comprises at least a major part of the cooling channel (182, 183,184).

8. The robotic work tool according to claim 7, wherein the main body (140)comprises integrally formed cooling channel walls (190, 191) and a separately attached cooling channel lid (192).

9. The robotic work tool according to any one of the claims 7 or 8, whereinthe main body (140) and a major part of the cooling channel (182) are formed in the same piece of material.

10. The robotic work tool according to any one of the previous claims, whereinthe control unit (110) is mounted in thermal connection with a cooling flange (188).

11. The robotic work tool according to any one of the previous claims, whereinthe airflow (F) is adapted to pass via at least one navigation sensor arrangement (175).