SE2051406A1

SE2051406A1 - Mulching arrangement and lawnmower

Info

Publication number: SE2051406A1
Application number: SE2051406A
Authority: SE
Inventors: Mats Svensson; Rickard Bergh
Original assignee: Husqvarna Ab
Priority date: 2020-12-02
Filing date: 2020-12-02
Publication date: 2022-06-03
Also published as: DE102021131247A1

Abstract

A mulching arrangement (2) is disclosed configured to be attached to a lawnmower (1) to mulch vegetation, such as leaves. The mulching arrangement (2) comprises a mulching guard (3), and a mulching unit (5) configured to rotate in the mulching guard (3). The mulching unit (5) comprises a number of surfaces (21', 22’) being angled relative to a rotation plane (Pr) of the mulching unit (5) to generate an airflow in a direction (d1) transverse to the rotation plane (Pr) during operation of the mulching arrangement (2). The mulching guard (3) comprises one or more apertures (11) arranged in a top surface (13) of the mulching guard (3). The present disclosure further relates to lawnmower (1) comprising a mulching arrangement (2).

Description

Mulching Arrangement and Lawnmower TECHNICAL FIELDThe present disclosure relates to mulching arrangement configured to be attached to alawnmower to mulch vegetation, such as leaves. The present disclosure further relates to a lawnmower comprising a mulching arrangement.

BACKGROUND An average garden has a lot of grass to be cut. Many gardens also have a lot of trees, suchas fruit- or ornamental trees. When the autumn comes it is a lot of work to remove the leavesfrom the ground, which usually is performed by raking. Then, the leaves are usually collectedin big paper or plastic bags which are transported to the municipal waste disposal station. ltcan usually be 2-3 turns to drive it in a car or on a trailer. lt requires a lot of energy both torake and get rid of all the leaves. lf leaves are not raked it stifles the lawn and can make it lean over time.

A lawnmower is an apparatus capable of cutting grass of a lawn. Various types oflawnmowers exist on today's market. Examples are walk-behind mowers and self-propelledrobotic lawnmowers. A walk-behind mower is a lawnmower usually comprising an elongatedhandle allowing a user to push, and/or to guide, the lawnmower. Some walk-behind mowerscomprise a propulsion arrangement configured to drive one or more wheels of thelawnmower. Walk-behind mowers lacking a propulsion arrangement are sometimes referredto as “push mowers”. Some lawnmowers comprise a power unit in the form of an electricmotor configured to rotate the cutting unit and some lawnmowers comprise a power unit in the form of a combustion engine configured to rotate the cutting unit.

A self-propelled robotic lawnmower is a mower capable of cutting grass in areas in anautonomous manner. Some robotic lawnmowers require a user to set up a border wirearound a lawn that defines the area to be mowed. Such robotic lawnmowers use a sensor tolocate the wire and thereby the boundary of the area to be trimmed. ln addition to the wire,robotic lawnmowers may also comprise other types of positioning units and sensors, forexample sensors for detecting an event, such as a collision with an object within the area.The robotic lawnmower may move in a systematic and/or random pattern to ensure that thearea is completely cut. ln some cases, the robotic lawnmower uses the wire to locate arecharging dock used to recharge the one or more batteries. Generally, robotic lawnmowersoperate unattended within the area in which they operate. Examples of such areas are lawns, gardens, parks, sports fields, golf courts and the like.

Mulching is a process in which vegetation, such as leaves, are separated into small pieceswhich then falls down to the ground. Mulching is an environmental way to get rid ofvegetation, such as leaves. The micro life in the soil, worms and other animals can pull downthe small pieces of the vegetation in the lawn. The breakdown become new soil and youhave improved and fertilized the soil at the same time. However, mulching can be difficultpartly because of the fact that vegetation, such as leaves, tend to stick to the ground,especially in wet or damp conditions. Moreover, grass growing in the lawn is sensitive,especially in the autumn when leaves falls to the ground, and may easily become damaged upon mechanical contact.

Furthermore, generally, on today's consumer market, it is an advantage if products, such aslawnmowers and associated components, systems, and arrangements, have conditionsand/or characteristics suitable for being manufactured and assembled in a cost-efficient mannef.

SUMMARYlt is an object of the present invention to overcome, or at least alleviate, at least some of the above-mentioned problems and drawbacks.

According to a first aspect of the invention, the object is achieved by a mulching arrangementconfigured to be attached to a lawnmower to mulch vegetation, such as leaves. Themulching arrangement comprises a mulching guard, and a mulching unit configured to rotatein the mulching guard. The mulching unit comprises a number of surfaces being angledrelative to a rotation plane of the mulching unit to generate an airflow in a directiontransverse to the rotation plane during operation of the mulching arrangement. The mulching guard comprises one or more apertures arranged in a top surface of the mulching guard.

Since the mulching unit is configured to rotate in the mulching guard and comprises thesurfaces being angled relative to a rotation plane of the mulching unit, a turbulent airflow isgenerated in the mulching guard during operation capable of lifting vegetation, such asleaves, from the ground surface towards the mulching unit. Moreover, due to the one or moreapertures arranged in a top surface of the mulching guard, the turbulent airflow is generatedin the mulching guard is increased which improves the ability to lift vegetation from the ground surface towards the mulching unit. 3 Since the mulching arrangement is capable of lifting the vegetation from the ground surfacein an improved manner, the mulching result is improved also in wet or damp conditions. Thatis, in wet or damp conditions, vegetation such as leaves stick harder to the ground making itmore difficult to lift from the ground surface. However, due to the increased turbulent airflowis generated in the mulching guard, vegetation such as leaves can be lifted from the ground surface towards the mulching unit to be mulched also under such circumstances.

Moreover, since the mulching arrangement is capable of lifting vegetation from the groundsurface without touching the ground surface, the mulching arrangement is capable of mulching vegetation on a lawn in a gentle manner for grass in the lawn.

According to embodiments herein, the mulching arrangement may be used on a lawnmower,such as a self-propelled robotic lawnmower, wherein a cutting unit, and possible furthercomponents such as a skid plate, is/are removed and replaced with the mulchingarrangement, i.e. with at least the mulching guard and the mulching unit of the mulchingarrangement according to embodiments herein. The mulching guard may be attached to anunderside of the lawnmower at a predefined orientation relative to the lawnmower and themulching unit may be attached to a drive shaft of the lawnmower. ln this manner, a mulchingmachine is obtained capable of mulching leaves in an efficient and environmentally friendly mannef.

Accordingly, a mulching arrangement is provided overcoming, or at least alleviating, at leastsome of the above-mentioned problems and drawbacks. As a result, the above-mentioned object is achieved.

Optionally, the surfaces are angled relative to the rotation plane to generate an airflow in adirection towards the top surface of the mulching guard during operation of the mulchingarrangement. Thereby, an airflow is generated in a direction from the ground surface towardsthe top surface of the mulching guard during operation of the mulching arrangement. Sincethe mulching guard comprises one or more apertures arranged in the top surface, an efficientairflow can be generated from the ground surface towards the top surface to lift vegetationfrom the ground surface in an efficient manner. Accordingly, due to these features, a furtherimproved ability to lift vegetation from the ground surface is provided thus providing conditions for a further improved mulching result also in wet or damp conditions.

Optionally, the mulching arrangement is configured to be moved in a forward moving direction over a ground surface during operation of the mulching arrangement, and wherein 4 the mulching guard is configured to enclose at least a leading section of the mulching unitseen relative to the forward moving direction. Thereby, an enclosed space is provided atleast in a region of the leading section of the mulching unit which provides conditions for acontrolled and efficient airflow and transport of leaves from the ground surface towards themulching unit upon movement of a lawnmower comprising the mulching arrangement in aforward moving direction. Thus, a further improved ability to lift vegetation from the groundsurface is provided thus providing conditions for a further improved mulching result also in wet or damp conditions Optionally, the leading section of the mulching unit is a section of the mulching unit locatedbetween a rotation axis of the mulching unit and a leading edge of the mulching unit seen along the forward moving direction.

Optionally, the mulching guard is configured to enclose the entire circumference of themulching unit. Thereby, an enclosed space is provided for the mulching unit which providesconditions for a controlled and efficient airflow and transport of leaves from the groundsurface towards the mulching unit. Thus, a further improved ability to lift vegetation from theground surface is provided thus providing conditions for a further improved mulching resultalso in wet or damp conditions. Furthermore, since the mulching guard is configured toenclose the entire circumference of the mulching unit, a safer mulching arrangement isprovided. This is because the mulching guard can prevent objects from reaching themulching unit from the sides of the mulching unit. ln addition, since the mulching guard isconfigured to enclose the entire circumference of the mulching unit, active mulching sectionsof the mulching unit can be configured to have higher kinetic energy during operation of themulching arrangement. This because some legislation requires a guard enclosing the cuttingunit of a lawnmower in case active cutting sections of a cutting unit exceeds a certain kinetic energy or impact energy.

Optionally, the mulching guard is bowl-shaped. Thereby, an enclosed space is provided forthe mulching unit which provides conditions for a controlled and efficient airflow and transportof leaves from the ground surface towards the mulching unit. Thus, a further improved abilityto lift vegetation from the ground surface is provided thus providing conditions for a further improved mulching result also in wet or damp conditions.

Optionally, the one or more apertures is/are arranged in the top surface of a front section ofthe mulching guard. Thereby, an efficient airflow and transport of leaves is provided at the front section of the mulching guard. Thereby, the ability to lift vegetation from the ground surface is further improved when the mulching arrangement is moved in a forward moving direction over a ground surface.

Optionally, the front section of the mulching guard is a section of the mulching guard locatedbetween a rotation axis of the mulching unit and a leading edge of the mulching guard seen along a forward moving direction of the mulching arrangement.

Optionally, at least a front section of the mulching guard comprises a rounded edgeconfigured to face a ground surface during operation of the mulching arrangement. Thereby,a more effective airflow past the edge of the mulching guard is provided. ln addition, therounded edge prevents the mulching guard from getting stuck on different objects on the ground surface.

Optionally, the mulching unit comprises an edge section having a U-shape in a planecomprising a rotation axis of the mulching unit, and wherein the rounded edge is a surface ofthe edge section. Thereby, an even more effective airflow past the edge of the mulchingguard can be provided. ln addition, the rounded edge can prevent the mulching guard from getting stuck on different objects on the ground surface in a more efficient manner.

Optionally, the mulching guard is configured to be attached to a lawnmower at an angle suchthat a leading edge of the mulching guard is closer to a ground surface than a trailing edge ofthe mulching guard seen relative to a fonNard moving direction of the lawnmower. Thereby,an efficient airflow and transport of vegetation is ensured at a front section of the mulchingguard. Moreover, a mulching arrangement is provided capable of utilizing a positive inclination angle of the rotation axis of a drive shaft of a lawnmower.

Optionally, the mulching unit comprises a number of sharp leading edges, and wherein eachsurface of the number of surfaces is separate from the number of sharp leading edges.Thereby, an effective airflow and transport of vegetation from the ground surface can be ensured.

Optionally, the mulching unit comprises at least a first and a second surface each beingangled relative to the rotation plane of the mulching unit to generate an airflow in a directiontransverse to the rotation plane during operation of the mulching arrangement, wherein thesecond surface is arranged behind the first surface along a tangential direction of themulching unit, and wherein the first surface is angled at a first angle relative to the rotation plane and the second surface is angled at a second angle relative to the rotation plane, and 6 Wherein the second angle is greater than the first angle. Thereby, efficient aerodynamicproperties of the mulching unit can be provided to generate high airflow levels while avoidinghigh rotational resistance of the mulching unit. Accordingly, due to these features, an even more efficient mulching arrangement can be provided.

Optionally, the second surface is arranged behind the first surface seen along a movingdirection of the surfaces upon rotation of the mulching unit in an intended rotational direction.Thereby, efficient aerodynamic properties of the mulching unit can be provided to generatehigh airflow levels while avoiding high rotational resistance of the mulching unit. Accordingly, due to these features, an even more efficient mulching arrangement can be provided.

Optionally, the mulching unit comprises a first section comprising the first surface, andWherein the first section comprises a sharp leading edge arranged adjacent to the firstsurface. Thereby, a mulching unit is provided capable of generating an airflow in an efficient manner while having conditions for mulching vegetation in an efficient manner.

Optionally, the first angle is within the range of 1 - 25 degrees, or is within the range of 6 -18 degrees, and Wherein the second angle is within the range of 12 - 50 degrees, or is withinthe range of 30 - 45 degrees. Thereby, efficient aerodynamic properties of the mulching unitcan be ensured to generate high airflow levels while avoiding high rotational resistance of themulching unit. Accordingly, due to these features, an even more efficient mulching arrangement can be provided.

Optionally, each of the first and second surfaces is substantially planar. Thereby, a mulchingarrangement is provided capable of generating high airflow levels in an efficient manner andcapable of mulching vegetation in an efficient manner while having conditions and characteristics suitable for being manufactured in a cost-efficient manner.

Optionally, the mulching unit comprises a hub and a number of mulching members pivotallyattached at a periphery of the hub, and Wherein the number of surfaces is surfaces of themulching members. Thereby, a safer and more durable mulching arrangement is providedbecause a mulching member may pivot upon impact with an object, such as a stone, a stump, or a limb of a person or animal.

Optionally, the hub is disc-shaped. Thereby, an even safer and more operational reliable mulching arrangement is provided. This is because a disc-shaped hub is considerably less 7 likely to become stuck upon impact with an object, such as a stone, a stump, or a limb of a person or animal, as compared to a hub having another shape.

Optionally, the mulching unit comprising at least two mulching members arranged at differentdistances from a rotation axis of the mulching unit. Thereby, a mulching arrangement isprovided having conditions for mulching vegetation in a further efficient manner. This isbecause the at least two mulching members will mulch vegetation at different radiuses from the rotation axis of the mulching unit.

Optionally, each mulching member comprises a first and a second section comprising a firstand a second surface respectively, wherein each of the first and a second surfaces is angledrelative to the rotation plane of the mulching unit to generate an airflow in a directiontransverse to the rotation plane during operation of the mulching arrangement, and whereineach mulching member further comprises an attachment section pivotally attached to a hubof the mulching unit, and a connecting section connecting the first section to the attachmentsection. Thereby, a mulching arrangement is provided capable of generating high airflowlevels in an efficient manner and capable of mulching vegetation in an efficient manner whilehaving conditions and characteristics suitable for being manufactured in a cost-efficient mannef.

Optionally, the attachment section is parallel to the rotation plane. Thereby, a mulchingarrangement is provided capable of generating high airflow levels in an efficient manner andcapable of mulching vegetation in an efficient manner while having conditions and characteristics suitable for being manufactured and assembled in a cost-efficient manner.

Optionally, the connecting section is angled relative to the rotation plane and relative to aradial direction of the mulching unit. Thereby, a mulching arrangement is provided having conditions for mulching vegetation in a further efficient manner.

Optionally, the first section, the second section, the attachment section, and the connectingsection are formed by bending of one piece of a sheet material. Thereby, a mulchingarrangement is provided capable of generating high airflow levels in an efficient manner andcapable of mulching vegetation in an efficient manner while having conditions and characteristics suitable for being manufactured and assembled in a cost-efficient manner.

Optionally, each of the first section, the second section, the attachment section, and the connecting section is substantially planar. Thereby, a mulching arrangement is provided 8 capable of generating high airflow levels in an efficient manner and capable of mulchingvegetation in an efficient manner while having conditions and characteristics suitable for being manufactured and assembled in a cost-efficient manner.

According to a second aspect of the invention, the object is achieved by a lawnmowercomprising a motor and a mulching arrangement according to some embodiments of thepresent disclosure, wherein the motor is configured to rotate the mulching unit of the mulching arrangement.

Since the lawnmower comprises a mulching arrangement according to some embodiments,a lawnmower is provided capable of mulching vegetation in an efficient manner. Moreover,since the mulching arrangement is capable of lifting vegetation from the ground surfacewithout touching the ground surface, the mulching arrangement is capable of mulching in a gentle manner for grass in the lawn.

Accordingly, a lawnmower is provided overcoming, or at least alleviating, at least some of theabove-mentioned problems and drawbacks. As a result, the above-mentioned object is achieved.

Optionally, the lawnmower comprises lawnmower support members configured to abutagainst a ground surface in a first plane during operation of the lawnmower, and wherein thelawnmower is configured to rotate the mulching unit in a rotation plane being angled relativeto the first plane such that a leading edge of the mulching unit is closer to the first plane thana trailing edge of the mulching unit when the lawnmower moves in a forward movingdirection. Thereby, an efficient airflow and transport of vegetation is ensured at a frontsection of the mulching guard. Moreover, a lawnmower is provided capable of mulching vegetation in an efficient manner.

Optionally, the lawnmower comprises lawnmower support members configured to abutagainst a ground surface in a first plane during operation of the lawnmower, and wherein themulching guard is attached at an angle relative to the lawnmower such that a leading edge ofthe mulching guard is closer to the first plane than a trailing edge of the mulching guard whenthe lawnmower moves in a forward moving direction. Thereby, an efficient airflow andtransport of vegetation is ensured at a front section of the mulching guard. Moreover, amulching arrangement is provided capable of utilizing the positive inclination angle of the rotation axis of a drive shaft of a lawnmower. 9 Optionally, the lawnmower is arranged such that a kinetic energy of each mulching memberof the lawnmower is below 20 Joules, or is below 6 Joules, during operation of thelawnmower. Thereby, a lawnmower is provided having conditions for mulching vegetation in a safe and efficient manner.

Optionally, the lawnmower is arranged such that a kinetic energy of each mulching memberof the lawnmower is within the range of 1 - 6 Joules during operation of the lawnmower.Thereby, a lawnmower is provided having conditions for mulching vegetation in a safe and efficient manner.

Optionally, the lawnmower is a self-propelled autonomous robotic lawnmower. Thereby, alawnmower is provided capable of mulching vegetation in an efficient manner without the intervention or direct control of a user.

Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGSVarious aspects of the invention, including its particularfeatures and advantages, will bereadily understood from the example embodiments discussed in the following detailed description and the accompanying drawings, in which: Fig. 1 illustrates a perspective view of a lawnmower according to some embodiments of thepresent disclosure, Fig. 2 illustrates a perspective view of an underside of the lawnmower illustrated in Fig. 1,Fig. 3 illustrates an enlarged view of a mulching arrangement of the lawnmower illustrated inFig. 2, Fig. 4 illustrates a cross section of the mulching arrangement illustrated in Fig. 3, Fig. 5 illustrates a perspective view of a mulching member of the mulching unit according tothe embodiments illustrated in Fig. 2 - Fig. 4, Fig. 6 illustrates a side view of the mulching member illustrated in Fig. 5, Fig. 7 illustrates a mulching arrangement according to some further embodiments, and Fig. 8 schematically illustrates a mulching unit according to some embodiments of a mulching arrangement according to the present disclosure.

DETAILED DESCRIPTION Aspects of the present invention will now be described more fully. Like numbers refer to likeelements throughout. Well-known functions or constructions will not necessarily be described in detail for brevity and/or clarity.

Fig. 1 illustrates a perspective view of a lawnmower 1 according to some embodiments of thepresent disclosure. According to the illustrated embodiments, the lawnmower 1 is a self-propelled autonomous robotic lawnmower 1 capable of navigating and operating an area inan autonomous manner in an area without the intervention or the direct control of a user. Forreasons of brevity and clarity, the self-propelled autonomous robotic lawnmower 1 is in someplaces herein referred to as “the robotic lawnmower 1” or simply the “lawnmower 1”.According to further embodiments, the lawnmower 1 may be another type of lawnmower,such as a walk-behind mower or a push mower. According to the embodiments herein, thelawnmower 1 is a small or mid-sized lawnmower 1 configured to be used to cut grass inareas used for aesthetic and recreational purposes, such as gardens, parks, city parks, sports fields, lawns around houses, apartments, commercial buildings, offices, and the like.

The lawnmower 1 comprises a lawnmower body 16 and a number of lawnmower supportmembers 41,41' each configured to abut against a ground surface 15 in a first plane P1during operation of the lawnmower 1 to support the lawnmower body 16. The lawnmowerbody 16, as referred to herein, may also be referred to as a lawnmower chassis. Accordingly,the first plane P1 will extend along a ground surface 15 when the lawnmower 1 is positionedon a flat ground surface 15. According to the illustrated embodiments, the lawnmowersupport members 41,41' is wheels 41,41' of the lawnmower 1. According to the illustratedembodiments, the lawnmower1 comprises four wheels 41, 41', namely two drive wheels 41and two support wheels 41 '_ The drive wheels 41 of the lawnmower 1 may each be poweredby an electrical motor of the lawnmower 1 to provide motive power and/or steering of thelawnmower 1. ln Fig. 1, a longitudinal direction ld of the lawnmower1 is indicated. Thelongitudinal direction ld of the lawnmower 1 extends in a longitudinal plane of the lawnmower1. The longitudinal plane is parallel to the first plane P1. The longitudinal direction ld of thelawnmower1 is thus parallel to the first plane P1 and thus also to a ground surface 15 whenthe lawnmower 1 is positioned onto a flat ground surface 15. Moreover, the longitudinaldirection ld of the lawnmower 1 is parallel to a forward moving direction fd of the lawnmower1 as well as a reverse moving direction of the lawnmower 1. The reverse moving direction is opposite to the fon/vard moving direction fd.

According to the illustrated embodiments, the drive wheels 41 of the lawnmower 1 are non- steered wheels having a fix rolling direction in relation to the lawnmower body 16. The 11 respective rolling direction of the drive wheels 41 of the lawnmower 1 is substantially parallelto the longitudinal direction ld of the lawnmower 1. According to the illustrated embodiments,the support Wheels 41' are non-driven wheels. Moreover, according to the illustratedembodiments, the support wheels 41' can pivot around a respective pivot axis such that therolling direction of the respective support Wheel 41' can follow a travel direction of the lawnmower 1.

As understood from the above, when the drive wheels 41, 41' of the lawnmower 1 are rotatedat the same rotational velocity in a fonNard rotational direction, and no wheel s|ip is occurring,the lawnmower 1 will move in the forward moving direction fd indicated in Fig. 1. Likewise,when the drive wheels 41, 41' of the lawnmower 1 are rotated at the same rotational velocityin a reverse rotational direction, and no Wheel s|ip is occurring, the lawnmower 1 will move in the reverse moving direction.

According to the illustrated embodiments, the lawnmower 1 may be referred to as a four-Wheeled rear wheel driven lawnmower 1. According to further embodiments, the lawnmower1 may be provided with another number of wheels 41, 41 ', such as three Wheels. Moreover,according to further embodiments, the lawnmower 1 may be provided with anotherconfiguration of driven and non-driven Wheels, such as a front wheel drive or an all-wheel drive.

According to the illustrated embodiments, the lawnmower 1 comprises a control arrangement28. The control arrangement 28 may be configured to control propulsion of the lawnmower 1,and steer the lawnmower 1, by contro||ing electrical motors of the lawnmower 1 arranged todrive the drive wheels 41 of the lawnmower 1. According to further embodiments, the controlarrangement 28 may be configured to steer the lawnmower 1 by contro||ing the angle ofsteered wheels of the lawnmower 1. According to still further embodiments, the roboticlawnmower may be an articulated robotic lawnmower, wherein the control arrangement 28may be configured to steer the robotic lawnmower by contro||ing the angle betvveen frame portions of the articulated robotic lawnmower.

The control arrangement 28 may be configured to control propulsion of the lawnmower 1,and may be configured to steer the lawnmower 1 so as to navigate the lawnmower 1 in anarea to be operated. The lawnmower 1 may further comprise one or more sensors arrangedto sense a magnetic field of a wire, and/or one or more positioning units, and/or one or moresensors arranged to detect an impending or ongoing collision event with an object. ln addition, the lawnmower 1 may comprise a communication unit connected to the control 12 arrangement 28. The communication unit may be configured to communicate with a remotecommunication unit to receive instructions therefrom and/or to send information thereto. Thecommunication may be performed wirelessly over a wireless connection such as the internet,or a wireless local area netvvork (WLAN), or a wireless connection for exchanging data overshort distances using short-wavelength, i.e. ultra-high frequency (UHF) radio waves in theindustrial, scientific, and medical (ISM) band from 2.4 to 2.486 GHz.

The control arrangement 28 may be configured to control propulsion of the lawnmower 1, and steer the lawnmower 1, so as to navigate the lawnmower 1 in a systematic and/orrandom pattern to ensure that an area is completely covered, using input from one or more ofthe above described sensors and/or units. Furthermore, the lawnmower 1 may comprise oneor more batteries arranged to supply electricity to components of the lawnmower 1. As anexample, the one or more batteries may be arranged to supply electricity to electrical motors of the lawnmower 1 by an amount controlled by the control arrangement 28.

The lawnmower1 comprises a mulching arrangement 2. The mulching arrangement 2 is configured to mulch vegetation, such as leaves, as is further explained herein.

Fig. 2 illustrates a perspective view of an underside of the lawnmower 1 illustrated in Fig. 1.As seen in Fig. 2, the mulching arrangement 2 comprises a mulching guard 3 and a mulchingunit 5. The mulching guard 3 is configured to be attached to the lawnmower body 16 in apredetermined orientation relative to the lawnmower body 16. The mulching unit 5 isconfigured to rotate inside the mulching guard 3. The mulching arrangement 2 may beconfigured to be attached to a lawnmower 1 by a user, wherein the user may replace acutting unit of the lawnmower1 with the mulching arrangement 2 when wanting to mulchvegetation, such as leaves. The mulching unit 5 is configured to be attached to a drive shaftof the lawnmower 1, which drive shaft is configured to rotate the cutting unit when thelawnmower 1 is used for cutting grass. The mulching arrangement 2 as referred to herein,may be sold as a mulching kit comprising at least the mulching guard 3 and the mulching unit5 which allows a user to convert a lawnmower1 into a mulching machine capable of mulching vegetation, such as leaves, as is further explained herein.

Fig. 3 illustrates an enlarged view of the mulching arrangement 2 of the lawnmower1illustrated in Fig. 2. According to the embodiments illustrated in Fig. 2 and Fig. 3, themulching unit 5 comprises a hub 6 and a number of mulching members 7 pivotally attachedat a periphery of the hub 6. Moreover, according to these embodiments, the hub 6 is disc- shaped. According to further embodiments, the mulching unit 5 may have a different layout, 13 as is further explained herein. The mulching unit 5 is configured to be rotated in an intendedrotational direction Dr around a rotation aXis AX by a motor of a lawnmower, such as a lawnmower illustrated in Fig. 1 and Fig. 2.

Fig. 4 illustrates a cross section of the mulching arrangement 2 illustrated in Fig. 3. ln Fig. 4,the cross section is made in a plane comprising the rotation aXis AX of the mulching unit 5.Moreover, in Fig. 4, the mulching arrangement 2 is illustrated as being attached to a drivingassembly 60 of a lawnmower. The lawnmower may be a lawnmower 1 according to theembodiments illustrated in Fig. 1 and Fig. 2. The driving assembly 60 may be rigidly attachedto the lawnmower body 16 of the lawnmower 1. The driving assembly 60 comprises a motor8 configured to rotate the mulching unit 5 around the rotation aXis AX. According to theillustrated embodiments, the motor 8 is an electric motor. ln Fig. 4, a rotation plane Pr of themulching unit 5 is indicated. The rotation plane Pr is a plane in which the mulching unit 5rotates during operation of the mulching arrangement 2. The rotation plane Pr of the mulching unit 5 is perpendicular to the rotation aXis AX of the mulching unit 5.

Below, simultaneous reference is made to Fig. 1 - Fig. 4, if not indicated othenNise. Themulching unit 5 comprising a number of surfaces 21' being angled relative to the rotationplane Pr of the mulching unit 5 to generate an airflow in a direction d1 transverse to therotation plane Pr during operation of the mulching arrangement 2, i.e. during rotation of themulching unit 5 in the intended rotational direction Dr around the rotation aXis AX. Moreover,as indicated in Fig. 2 - Fig. 4, the mulching guard 3 comprises a number of apertures 11.The apertures 11 are arranged in a top surface 13 of the mulching guard 3. Due to thesefeatures, an mulching arrangement 2 is provided capable of mulching vegetation, such asleaves, in an efficient manner by lifting vegetation from the ground surface 15 towards themulching unit 5 using a turbulent airflow is generated in the mulching guard 3. Due to thenumber of apertures 11 arranged in a top surface 13 of the mulching guard 3, the turbulentairflow is magnified which provides improved conditions for lifting vegetation, such as leaves,from the ground surface 15. The turbulent airflow is magnified partly because airflow is allowed through the apertures 11.

According to the illustrated embodiments, the surfaces 21' are angled relative to the rotationplane Pr to generate an airflow in a direction d1 towards the top surface 13 of the mulchingguard 3 during operation of the mulching arrangement 2, i.e. during rotation of the mulchingunit 5 in the intended rotational direction Dr around the rotation aXis AX. ln this manner,vegetation, such as leaves, can be lifted in an efficient manner from the ground surface 15 towards the mulching unit 5. 14 The mulching arrangement 2 is configured to be moved in a forward moving direction fd overa ground surface 15 during operation of the mulching arrangement 2. ln Fig. 3 and Fig. 4, thefonNard moving direction fd is indicated. The fonNard moving direction fd of the mulchingarrangement 2 coincides with the fonNard moving direction fd of the lawnmower 1 when themulching arrangement 2 is attached to a lawnmower 1. According to the i||ustratedembodiments, the mulching guard 3 is configured to enclose at least a leading section 5' ofthe mulching unit 5 seen relative to the fonNard moving direction fd. The leading section 5' ofthe mulching unit 5 is a section of the mulching unit 5 located between the rotation axis Ax ofthe mulching unit 5 and a leading edge 51 of the mulching unit 5 seen along the fon/vardmoving direction fd. Thereby, a turbulent airflow can be ensured inside a front section 3' of the mulching guard 3.

However, as seen in Fig. 2 - Fig. 4, according to the i||ustrated embodiments, the mulchingguard 3 is configured to enclose the entire circumference of the mulching unit 5. Thereby,turbulent airflow can be ensured inside the full mulching guard 3. Moreover, a safer mulchingarrangement 2 is provided because the mulching guard 3 may protect the mulching unit 5from objects reaching the mulching unit 5 from sides thereof. Moreover, according to thei||ustrated embodiments, the mulching guard 3 is bowl-shaped which ensures a turbulent airflow inside the full mulching guard 3.

As mentioned above, the lawnmower 1 comprises a number of lawnmower support members41, 41' configured to abut against a ground surface 15 in a first plane P1 during operation ofthe lawnmower 1. The first plane P1 is also indicated in Fig. 4. The first plane P1 will extendalong a ground surface 15 when the lawnmower 1 is positioned on a flat ground surface 15.The top surface 13 of the mulching guard 3 has a surface normal pointing towards the firstplane P1, and thus also pointing towards a ground surface 15 when a lawnmower comprisingthe mulching arrangement 2 is positioned onto a ground surface 15. The top surface 13 ofthe mulching guard 3 is located further from the first plane P1 than other surfaces andportions of the mulching guard 3, such as side surfaces of the mulching guard 3 enclosingthe mulching unit 5. The top surface 13 of the mulching guard 3 may also be referred to as an upper surface of the mulching guard 3.

According to the i||ustrated embodiments, the apertures 11 are arranged in the top surface13 of the front section 3' of the mulching guard 3. The front section 3' of the mulching guard 3is a section of the mulching guard 3 located between the rotation axis Ax of the mulching unit and a leading edge 31 of the mulching guard 3 seen along a fon/vard moving direction fd of the mulching arrangement 2. According to the illustrated embodiments, the mulching guard 3comprises four elongated openings in the top surface 13 of the front section 3' thereof.According to further embodiments, the mulching guard 3 may comprise another number ofapertures 11 and the apertures 11 may have another form than elongated, such as circular.Each of the apertures 11 is an opening allowing flow of air and matter therethrough. Theapertures 11 may also be referred to as openings. According to the illustrated embodiments,the mulching guard 3 has a closed back section 3”. The back section 3" of the mulchingguard 3 is a section of the mulching guard 3 located bet\Neen the rotation axis Ax of themulching unit 5 and a trailing edge 32 of the mulching guard 3 seen along a fonNard movingdirection fd of the mulching arrangement 2. ln other words, according to the illustratedembodiments, the top surface 13 of the back section 3" of the mulching guard 3 comprisesno apertures. However, according to further embodiments, also the top surface 13 of the back section 3" of the mulching guard 3 may comprise one or more apertures 11.

According to the illustrated embodiments, the mulching guard 3 is configured to be attachedto a lawnmower1 at an angle such that a leading edge 31 of the mulching guard 3 is closerto a ground surface 15 than a trailing edge 32 of the mulching guard 3 seen relative to afonNard moving direction fd of the lawnmower 1 and thus also seen relative to the fonNardmoving direction fd of the mulching arrangement 2. Due to these features, an efficientmulching of vegetation is provided. This because when the mulching arrangement 2 ismoved in the fonNard moving direction fd over a ground surface 15, vegetation on the groundsurface will first reach the front section 3' of the mulching guard 3 and can be sucked from the ground surface 15 in a direction towards the mulching unit 5 in an efficient manner.

As best seen in Fig. 4, according to the illustrated embodiments, the mulching guard 3comprises a rounded edge 35' configured to face a ground surface 15 during operation of themulching arrangement 2. Accordingly, the rounded edge 35' is also configured to face thefirst plane P1 when the mulching arrangement 2 is attached to a lawnmower 1. Moreover,according to the illustrated embodiments, the mulching unit 5 comprises an edge section 35having a U-shape in a plane comprising the rotation axis AX of the mulching unit 5, andwherein the rounded edge 35' is a surface of the edge section 35. Due to these features, aneffective airflow past the edge 35' of the mulching guard 3 is provided. ln addition, therounded edge 35' can prevent the mulching guard 3 from getting stuck on different objects on the ground surface 15 in a more efficient manner.

According to the illustrated embodiments, the mulching guard 3 is attached at an angle relative to the lawnmower1 such that a leading edge 31 of the mulching guard 3 is closer to 16 the first plane P1 than a trailing edge 32 of the mulching guard 3 when the lawnmower1moves in a forward moving direction fd. ln Fig. 4, a second plane P2 is indicated. The secondplane P2 extends through the edge section 35 of the mulching guard including the leadingedge 31 and the trailing edge 32 of the mulching guard 3. According to the illustratedembodiments, the mulching guard 3 is attached to the lawnmower1 such that an anglebetween the first plane P1 and a second plane P2 is approximately 2.5 degrees. Accordingto further embodiments, the mulching guard 3 may be attached to the lawnmower 1 such thatthe angle between the first plane P1 and a second plane P2 is within the range of 0 - 8 degrees, or is within the range of 1.5 - 3.5 degrees.

The mulching guard 3 may be configured to be attached to a lawnmower 1 at apredetermined orientation relative to the lawnmower 1 by comprising an attachment interfaceensuring that the mulching guard 3 obtains predetermined orientation when the mulchingguard 3 is attached to the lawnmower 1. The mulching guard 3 may be attached to thelawnmower 1 using screws, bults, nuts, snap-fit arrangements, and/or other types offastening elements. The predetermined orientation may be an orientation in which apredetermined angle is obtained between the first and second planes P1 and P2. Moreover,the predetermined orientation may be an orientation in which the front section 3' of themulching guard 3 is positioned to point fon/vard seen along the forward moving direction fd ofthe lawnmower 1, i.e. such that the fonNard moving direction fd of the mulching guard coincides with the fonNard moving direction fd of the lawnmower 1.

Moreover, according to the illustrated embodiments, the rotation axis Ax of the mulching unit5 is angled with a positive inclination angle relative to a surface normal of the ground surface15 and thus also angled relative to a surface normal of the first plane P1. Thus, thelawnmower 1 is configured to rotate the mulching unit 5 in a rotation plane Pr being angledrelative to the first plane P1 such that a leading edge 51 of the mulching unit 5 is closer to thefirst plane P1 than a trailing edge 52 of the mulching unit 5 when the lawnmower1 moves ina fonNard moving direction fd. According to the illustrated embodiments, the angle betweenthe rotation plane Pr of the mulching unit 5 and the first plane P1 is approximately 5 degrees.According to further embodiments, the angle between the rotation plane Pr of the mulchingunit 5 and the first plane P1 may be within the range of 0 - 10 degrees, or may be within therange of 2 - 7 degrees. The feature that the angle between the rotation plane Pr of themulching unit 5 and the first plane P1 is within the range of 0 - 10 degrees may be coveredby the expression that the mulching unit 5 is configured to rotate in a rotation plane Prsubstantially parallel to the first plane P1 or substantially parallel to a ground surface 15.

Likewise, feature that the angle between the rotation plane Pr of the mulching unit 5 and the 17 first plane P1 is within the range of 0 - 10 degrees may be covered by the expression thatthe mulching unit 5 is configured to rotate around a rotation axis Ax substantially perpendicular to the first plane P1 or substantially perpendicular to a ground surface 15.

Fig. 5 i||ustrates a perspective view of a mulching member 7 of the mulching unit 5 accordingto the embodiments i||ustrated in Fig. 2 - Fig. 4. Below, simultaneous reference is made toFig. 1 - Fig. 5, if not indicated othenNise. The mulching member 7 comprises an attachmentsection 23. The mulching member 7 is configured to be pivotally attached to a hub 6 of themulching unit 5 around a pivot axis pA. According to the i||ustrated embodiments, theattachment section 23 comprises a through hole 55. According to the i||ustratedembodiments, the mulching member 7 is configured to be pivotally attached to the hub 6 by a fastening element extending through the through hole 55.

The mulching member 7 further comprises a first and a second section 21, 22 comprising afirst and a second surface 21', 22' respectively. That is, the first section 21 of the mulchingmember 7 comprises the first surface 21' and the second section 22 of the mulching member7 comprises the second surface 22'. Each of the first and a second surfaces 21', 22' isangled relative to the rotation plane Pr of the mulching unit 5 to generate an airflow in adirection d1 transverse to the rotation plane Pr during operation of the mulching arrangement2.

Fig. 6 i||ustrates a side view of the mulching member 7 i||ustrated in Fig. 5. Below,simultaneous reference is made to Fig. 1 - Fig. 6, if not indicated otherwise. ln Fig. 5 andFig. 6, a moving direction md of the mulching member 7 is indicated. The mulching member7 moves in the moving direction md upon rotation of the mulching unit 5 in the intendedrotational direction indicated in Fig. 3. Obviously, the moving direction md is parallel to therotation plane Pr of the mulching unit 5 and perpendicular to a radial direction rd of themulching unit 5. Moreover, the moving direction md of the mulching unit 5 is parallel to a tangential direction Td of the mulching unit 5.

As best seen in Fig. 5 and Fig. 6, according to the i||ustrated embodiments, the secondsurface 22' is arranged behind the first surface 21' seen along a moving direction md of thesurfaces 21', 22' upon rotation of the mulching unit 5 in an intended rotational direction Dr. lnother words, the second surface 22' is arranged at a trailing edge of the first surface 21' seenalong the moving direction md of the surfaces 21', 22' upon rotation of the mulching unit 5 inan intended rotational direction Dr. Moreover, as indicated in Fig. 6, the first surface 21' is angled at a first angle a1 relative to the rotation plane Pr and the second surface 22' is 18 angled at a second angle a2 relative to the rotation plane Pr, and wherein the second anglea2 is greater than the first angle a1. Thereby, efficient aerodynamic properties of the mulching member 7 is provided to generate high airflow levels while avoiding high rotationalresistance of the mulching unit 5. Accordingly, due to these features, an even more efficient mulching arrangement 2 is provided.

According to the illustrated embodiments, the first angle a1 is approximately 12 degrees andthe second angle a2 is approximately 37 degrees. Thus, according to the illustratedembodiments, the angle betvveen the first and second surfaces 21 ', 22' is approximately 25degrees. According to further embodiments, the first angle a1 may be within the range of 1 -25 degrees, or may be within the range of 6 - 18 degrees, and the second angle a2 may be within the range of 12 - 50 degrees, or may be within the range of 30 - 45 degrees.

The mulching member 7 comprises a sharp leading edge 17, i.e. a sharp edge at a frontsection of the mulching member 7 seen along the moving direction md of the mulchingmember 7. As seen in Fig. 5 and Fig. 6, the first and second surfaces 21', 22' are eachseparate from each of the number of sharp leading edges 17. Moreover, according to theillustrated embodiments, the first section 21 of the mulching member 7 comprises the sharpleading edge 17, wherein the sharp leading edge 17 is arranged adjacent to the first surface21”. The sharp leading edge 17 is configured to mulch, i.e. cut, vegetation upon rotation of the mulching unit 5.

As best seen in Fig. 6, according to the illustrated embodiments, the attachment section 23of the mulching member 7 is parallel to the rotation plane Pr. Moreover, the mulchingmember 7 comprises a connecting section 25 connecting the first section 21 to theattachment section 23. The second section 22 is attached to the attachment section 23 viathe first section 21. As can be seen in Fig. 5 and Fig. 6, according to the illustratedembodiments, the connecting section 25 is angled relative to the rotation plane Pr andrelative to a radial direction rd of the mulching unit 5. Moreover, according to the illustratedembodiments, the first section 21, the second section 22, the attachment section 23, and theconnecting section 25 are formed by bending of one piece of a sheet metal material.Moreover, each of the first section 21, the second section 22, the attachment section 23, andthe connecting section 25 is substantially planar. Thus, according to the illustratedembodiments, each of the first and second surfaces 21 ', 22' is substantially planar. Due tothese features, a mulching member 7 is provided having conditions for mulching vegetationin an efficient manner while having conditions and characteristics suitable for being manufactured and assembled in a cost-efficient manner. 19 Even though the mulching member 7 according to the illustrated embodiments comprisestwo surfaces 21', 22' having different angles relative to the rotation plane Pr of the mulchingunit 5, the mulching members 7 of the mulching unit 5 may comprise only one surface angled relative to the rotation plane Pr of the mulching unit.

According to the embodiments explained with reference to Fig. 2 - Fig. 6, the mulching unit 5comprising three mulching members 7 arranged at a periphery of the hub 6 of the mulchingunit 5. According to further embodiments, the mulching unit 5 may comprise another numberof mulching members 7, such as one, two, four, five, or the like. According to someembodiments, the mulching unit 5 may comprise at least two mulching members 7 arrangedat different distances from a rotation axis Ax of the mulching unit 5. Thereby, a mulchingarrangement 2 is provided having conditions for mulching vegetation in a further efficientmanner. This is because the at least two mulching members 7 will mulch vegetation at different radiuses from the rotation axis Ax of the mulching unit 5. ln summary, according to the embodiments illustrated in Fig. 2 - Fig. 6, the number ofsurfaces 21', 22' being angled relative to a rotation plane Pr of the mulching unit 5 togenerate an airflow in a direction d1 transverse to the rotation plane Pr during operation ofthe mulching arrangement 2 are surfaces 21 ', 22' of the mulching members 7 of the mulching unit 5.

Fig. 7 illustrates a mulching arrangement 2 according to some further embodiments. Themulching arrangement 2 illustrated in Fig. 7 comprises the same features, functions, andadvantages as the mulching arrangement 2 explained with reference to Fig. 1 - Fig. 6, withsome differences explained below. According to the embodiments illustrated in Fig. 7, themulching arrangement 2 comprises a mulching unit 5 comprising a fix arm arrangement 57instead of a hub and a number of mulching members pivotally attached to the hub. lnstead,the mulching arrangement 2 comprises a number of mulching sections 7' rigidly attached to arespective arm of the fix arm arrangement 57. According to the embodiments illustrated inFig. 7, the mulching unit 5 comprises three mulching sections 7' rigidly attached to arespective arm of the fix arm arrangement 57. Each mulching section 7' may have identicalform, features, functions and advantages as the form, features, functions and advantages ofthe mulching members 7 of the mulching arrangement 2 explained with reference to Fig. 1 -Fig. 6, except the pivoting feature of the mulching members 7 explained with reference toFig. 2 - Fig. 6. Moreover, the mulching arrangement 2 illustrated in Fig. 7 comprises a mulching guard 3 according to the embodiments explained with reference to Fig. 2 - Fig. 4.

Therefore, the features, functions, and advantages of the mulching arrangement 2 illustrated in Fig. 7 are not further explained herein.

Fig. 8 schematically illustrates a mulching unit 5 according to some embodiments of amulching arrangement 2 according to the present disclosure. The mulching unit 5 comprisesa hub 6 and a mulching member 7 arranged at a periphery of the hub 6. For reasons ofbrevity and clarity, the mulching unit 5 in Fig. 8 is illustrated as comprising only one mulchingmember 7. However, the mulching unit 5 may comprise more than one mulching member 7,such as two, three, four, or five mulching members 7. The kinetic energy of each mulchingmember 7 of the mulching unit 5 as described herein may be determined by means of the following formula: Ek=1/2*mv^2 where Ek is the kinetic energy, in Joules; m is the mass, of reckonable length L of the mulching member 7, in kilograms,wherein the reckonable length L of the mulching member 7 may be the length Lbetween the pivot axis pA of the mulching member 7 and the radially outerportion 72 of a mulching member 7; v is the maximum attainable velocity of the point z which is half\Nay along the reckonable length L of the mulching member 7, in metres per second.

Therefore v=0,1047n[r-L/2] wheren is the maximum rotational speed, in revolutions per minute;r is the distance from the rotational axis Ax of the mulching unit 5 to the radiallyouter portion 72 of a mulching member 7, in metres;L is the reckonable length of the mulching member 7, in metres.

The pivot axis pA of a mulching member 7 coincides with a centre line of a hole 55 configured for attachment of the mulching member 7 as explained with reference to Fig. 5.

According to some embodiments of the mulching arrangement 2, the distance r from therotational axis Ax of the mulching unit 5 to the radially outer portion 72 of a mulching member7 is within the range of 3 cm to 25 cm, or is within the range of 6 cm to 12 cm, or is approximately 8.5 cm. 21 According to some embodiments of the mulching unit 5, the reckonable length L of themulching member 7 is within the range of 1 cm to 9 cm, or is within the range of 1.7 cm to 6 cm, or is approximately 3.4 cm.

According to some embodiments of the mulching unit 5, the mass m, of reckonable length Lof the mulching member 7, is within the range of 1 to 40 grams, or is within the range of 1.7 to 6.5 grams, or is approximately 3.4 grams.

According to some embodiments, the thickness of the mulching member 7, i.e. the thicknessof the mulching member 7 measured in a direction perpendicular to the rotational plane ofthe mulching member 7, is within the range of 0.2 mm to 4.5 mm, or is within the range of 0.32 mm to 1.2 mm, or is approximately 0.63 mm.

According to some embodiments, the total height h2 of the mulching member 7 of themulching unit 5 is within the range of 0.7 cm to 6 cm, or is within the range of 1.5 cm to 3.5 cm, or is approximately 2.6 cm.

According to some embodiments, the height h1 of the first section 21 of the mulchingmember 7 of the mulching unit 5 is within the range of 0.7 cm to 5 cm, or is within the range of 1.3 cm to 2.5 cm, or is approximately 2 cm.

According to some embodiments of the mulching arrangement 2, the diameter of the hub 6 ofthe mulching unit 5 is within the range of 5 cm to 39 cm, or is within the range of 8 cm to 20 cm, or is approximately 14.3 cm.

According to some embodiments, the maximum attainable velocity v of the point z which ishalf way along the reckonable length L of the mulching member 7 is within the range of 10 to80 metres per second, or is within the range of 15 to 50 metres per second, or is approximately 34 metres per second.

According to some embodiments, the maximum rotational speed of the mulching unit 5 iswithin the range of 1 000 to 8 500 revolutions per minute, or is within the range of 2 400 to 7 200 revolutions per minute, or is approximately 4 800 revolutions per minute.

All of the above distances and measurements may be measured in the rotation plane of the mulching unit 5, i.e. in a plane perpendicular to the rotation axis Ax of the mulching unit 5. 22 According to some embodiments, the lawnmower 1 is arranged such that a kinetic energy ofeach mulching member 7 is below 20 Joules, or is below 6 Joules, during operation of the lawnmower 1.

According to some embodiments, the lawnmower 1 is arranged such that a kinetic energy ofeach mulching member 7 is within the range of 1 - 6 Joules during operation of the lawnmower 1. lt is to be understood that the foregoing is illustrative of various example embodiments andthat the invention is defined only by the appended claims. A person skilled in the art willrealize that the example embodiments may be modified, and that different features of theexample embodiments may be combined to create embodiments other than those describedherein, without departing from the scope of the present invention, as defined by the appended claims.

As used herein, the term "comprising" or "comprises" is open-ended, and includes one ormore stated features, elements, steps, components, or functions but does not preclude thepresence or addition of one or more other features, elements, steps, components, functions, or groups thereof.

Claims

1. CLAIMS A mulching arrangement (2) configured to be attached to a lawnmower (1) to mulchvegetation, such as leaves, wherein the mulching arrangement (2) comprises:- a mulching guard (3), and- a mulching unit (5) configured to rotate in the mulching guard (3), the mulching unit (5) comprising a number of surfaces (21', 22') being angled relativeto a rotation plane (Pr) of the mulching unit (5) to generate an airflow in a direction (d1)transverse to the rotation plane (Pr) during operation of the mulching arrangement (2),and wherein the mulching guard (3) comprises one or more apertures (11) arranged in a top surface (13) of the mulching guard (3). _ The mulching arrangement (2) according to claim 1, wherein the surfaces (21', 22') are angled relative to the rotation plane (Pr) to generate an airflow in a direction (d1) towardsthe top surface (13) of the mulching guard (3) during operation of the mulching arrangement (2). The mulching arrangement (2) according to claim 1 or 2, wherein the mulchingarrangement (2) is configured to be moved in a forward moving direction (fd) over aground surface (15) during operation of the mulching arrangement (2), and wherein themulching guard (3) is configured to enclose at least a leading section (5') of the mulching unit (5) seen relative to the forward moving direction (fd). _ The mulching arrangement (2) according to any one of the preceding claims, wherein the mulching guard (3) is configured to enclose the entire circumference of the mulching unit (5). The mulching arrangement (2) according to any one of the preceding claims, wherein the mulching guard (3) is bowl-shaped. The mulching arrangement (2) according to any one of the preceding claims, wherein theone or more apertures (11) is/are arranged in the top surface (13) of a front section (3') of the mulching guard (3). The mulching arrangement (2) according to any one of the preceding claims, wherein at least a front section (3') of the mulching guard (3) comprises a rounded edge (35')configured to face a ground surface (15) during operation of the mulching arrangement (2)- The mulching arrangement (2) according to any one of the preceding claims, wherein themulching guard (3) is configured to be attached to a lawnmower (1) at an angle such thata leading edge (31) of the mulching guard (3) is closer to a ground surface (15) than atrailing edge (32) of the mulching guard (3) seen relative to a fonNard moving direction (fd) of the lawnmower (1 ). The mulching arrangement (2) according to any one of the preceding claims, wherein themulching unit (5) comprises a number of sharp leading edges (17), and wherein eachsurface (21 ', 22') of the number of surfaces (21', 22') is separate from the number of sharp leading edges (17). The mulching arrangement (2) according to any one of the preceding claims, wherein themulching unit (5) comprises at least a first and a second surface (21', 22') each beingangled relative to the rotation plane (Pr) of the mulching unit (5) to generate an airflow ina direction (d1) transverse to the rotation plane (Pr) during operation of the mulchingarrangement (2), wherein the second surface (22') is arranged behind the first surface(21') along a tangential direction (Td) of the mulching unit (5), wherein the first surface(21') is angled at a first angle (a1) relative to the rotation plane (Pr) and the secondsurface (22') is angled at a second angle (a2) relative to the rotation plane (Pr), and wherein the second angle (a2) is greater than the first angle (a1). The mulching arrangement (2) according to claim 10, wherein the second surface (22') isarranged behind the first surface (21') seen along a moving direction (md) of thesurfaces (21', 22') upon rotation of the mulching unit (5) in an intended rotational direction (Dr). The mulching arrangement (2) according to claim 10 or 11, wherein the mulching unit (5)comprises a first section (21) comprising the first surface (21'), and wherein the firstsection (21) comprises a sharp leading edge (17) arranged adjacent to the first surface(21'). The mulching arrangement (2) according to any one of the claims 10 - 12, wherein the first angle (a1) is within the range of 1 - 25 degrees, or is within the range of 6 -degrees, and wherein the second angle (a2) is within the range of 12 - 50 degrees, or is within the range of 30 - 45 degrees. The mulching arrangement (2) according to any one of the preceding claims, wherein themulching unit (5) comprises a hub (6) and a number of mulching members (7) pivotallyattached at a periphery of the hub (6), and wherein the number of surfaces (21', 22') are surfaces (21', 22') of the mulching members (7). The mulching arrangement (2) according to c|aim 14, wherein the mulching unit (5)comprising at least two mulching members (7) arranged at different distances from a rotation axis (AX) of the mulching unit (5). The mulching arrangement (2) according to c|aim 14 or 15, wherein each mulchingmember (7) comprises a first and a second section (21, 22) comprising a first and asecond surface (21', 22') respectively, wherein each of the first and a second surfaces(21', 22') is angled relative to the rotation plane (Pr) of the mulching unit (5) to generatean airflow in a direction (d1) transverse to the rotation plane (Pr) during operation of themulching arrangement (2), and wherein each mulching member (7) further comprises anattachment section (23) pivotally attached to a hub (6) of the mulching unit (5), and a connecting section (25) connecting the first section (21) to the attachment section (23). The mulching arrangement (2) according to c|aim 16, wherein the connecting section(25) is angled relative to the rotation plane (Pr) and relative to a radia| direction (rd) of the mulching unit (5). A lawnmower (1) comprising a motor (8) and a mulching arrangement (2) according toany one of the preceding claims, wherein the motor (8) is configured to rotate the mulching unit (5) of the mulching arrangement (2). The lawnmower (1) according to c|aim 18, wherein the lawnmower (1) compriseslawnmower support members (41, 41 ') configured to abut against a ground surface (15)in a first plane (P1) during operation of the lawnmower (1), and wherein the mulchingguard (3) is attached at an angle relative to the lawnmower (1) such that a leading edge(31) of the mulching guard (3) is closer to the first plane (P1) than a trailing edge (32) ofthe mulching guard (3) when the lawnmower (1) moves in a forward moving direction(fd).20. The lawnmower (1) according to claim 18 or 19, wherein the lawnmower (1) is a self- propelled autonomous robotic lawnmower (1 ).