SE544974C2

SE544974C2 - Lawnmower with pivotable cutting unit

Info

Publication number: SE544974C2
Application number: SE2150080A
Authority: SE
Inventors: Anders Sjögren
Original assignee: Husqvarna Ab
Priority date: 2019-12-04
Filing date: 2020-02-24
Publication date: 2023-02-14
Also published as: SE2150080A1; SE2050200A1; SE544276C2

Abstract

A lawnmower (1) is disclosed comprising a lawnmower chassis (3), lawnmower support members (5, 5’) configured to abut against a ground surface (7) in a first plane (P1) during operation of the lawnmower (1), and a cutting unit (9) configured to operate in a cutting plane (PC). The cutting unit (9) is pivotally arranged relative to the lawnmower chassis (3) to pivot between a first position and a second position. The angle between the cutting plane (PC) and the first plane (P1) is different when the cutting unit (9) is in the second position than when the cutting unit (9) is in the first position.

Description

TECHNICAL FIELD The present disclosure relates to a lawnmower, such as a self-propelled autonomous robotic lawnmower.

BACKGROUND Various types of lawnmowers exist on today's market. Examples are walk-behind mowers, riding mowers, and self-propelled robotic lawnmowers. A walk-behind mower is a lawnmower usually comprising an elongated handle allowing a user to push, and/or to guide, the lawnmower. Some walk-behind mowers comprise a propulsion arrangement configured to drive one or more wheels of the lawnmower. Walk-behind mowers lacking a propulsion arrangement are sometimes referred to as “push mowers”. A riding mower is a mower comprising a seat for a user, a steering device, such as a steering wheel, and a motor configured to provide motive power to the riding mower. Usually, riding mowers are used to mow bigger lawns, gardens, parks, sports fields, golf courts or the like.

A self-propelled robotic lawnmower is a mower capable of cutting grass in areas in an autonomous manner. Some robotic lawnmowers require a user to set up a border wire around a lawn that defines the area to be mowed. Such robotic lawnmowers use a sensor to locate 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, for example 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 the area is completely cut. ln some cases, the robotic lawnmower uses the wire to locate a recharging dock used to recharge the one or more batteries. Generally, robotic lawnmowers operate unattended within the area in which they operate. Examples of such areas are lawns, gardens, parks, sports fields, golf courts and the like.

Some lawnmowers comprise an electric motor configured to rotate the cutting unit and some lawnmowers comprise a combustion engine configured to rotate the cutting unit. The use of an electric motor provides several advantages over the use of a combustion engine when it comes to emission levels, noise levels, operational reliability, and the need for service and repair. However, a problem associated with electrically powered lawnmowers is available operational time. Cutting grass requires a lot of energy and in riding mowers and self- propelled robotic lawnmowers, it is usually not practically possible to use a power cord to power the electric motor. Therefore, these types of lawnmowers usually comprise one ormore batteries configured to power the electric motor. When such one or more batteries are emptied, they must be recharged or replaced. One solution to prolong the available operational time could be to increase the size and/or the number of batteries. However, such a solution adds weight and costs to the lawnmower and in many cases, these is a practical limit for the size of the batteries of a lawnmower.

Energy consumption and available operational time also constitute problems for lawnmowers comprising a combustion engine. This because such lawnmowers comprise a tank accommodating fuel, and when such a tank is emptied, it must be replenished.

Furthermore, various types of lawnmowers, such as those described above, are associated with some mutual problems. One such problem is cutting result, which can be subdivided into visual cutting result and uniformity of cutting. The visual cutting result can be defined as the visual cutting result determined by a person viewing a mowed lawn. The uniformity of the cutting can be defined as uniformity of a length of the grass of a mowed lawn, i.e. if straws of the grass in a lawn are cut to a uniform length. So called cutting tracks can be formed When mowing a lawn. Cutting tracks are tracks in the lawn having different length of the grass than portions adjacent to the tracks. Cutting tracks have a negative impact on the cutting result and is especially problematic if the lawnmower is moving in systematic patterns.

Moreover, many lawns have a highly varying length and density of the grass prior to the cutting. That is, some portions of the lawn may have a significantly greater length and density of the grass than other portions of the lawn. The varying length and density of the grass prior to the cutting may be the result of varying soil qualities of the lawn, varying water levels in the lawn, varying nutrition levels in the lawn, varying illumination levels onto the lawn, varying grass types in the lawn, and the like. The cutting unit of a lawnmower will be subjected to a greater load when the lawnmower is reaching a portion of a lawn having greater length and density of the grass. The higher load Will slow down an operation speed of the cutting unit and Will increase energy consumption of the lawnmower. Moreover, the higher load may reduce the cutting result partly due to the slower operation speed of the cutting unit. ln addition, a too high load on the cutting unit may cause an obstruction of the cutting unit which may stop the cutting unit from operating.

Another problem associated with lawnmowers is build-up of vegetation, such as grass, onto various components of the lawnmower. The area of the lawnmower surrounding the cutting unit is particularly problematic. Firstly, the build-up of vegetation, such as grass, is most common in this area, and secondly, the build-up of grass in this area may significantlyincrease the energy consumption of the lawnmower and may even cause an obstruction of the cutting unit stopping the cutting unit from operating.

Still another problem associated with lawnmowers is co||ision between the cutting unit and objects other than grass and softer types of vegetation, such as stumps, stones, sticks, and the like. Collision between the cutting unit and such objects constitutes a problem because the cutting unit, as well as other parts of the lawnmower, may become damaged and/or subjected to premature wear. ln addition, generally, on today's consumer market, it is an advantage if products, such as lawnmowers, comprise different features and functions while the products have conditions and/or characteristics suitable for being manufactured and assembled in a cost-efficient mannef.

SUMMARY lt 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 lawnmower comprising a lawnmower chassis, lawnmower support members configured to abut against a ground surface in a first plane during operation of the lawnmower, and a cutting unit configured to operate in a cutting plane. The cutting unit is pivotally arranged relative to the lawnmower chassis to pivot between a first position and a second position. The angle between the cutting plane and the first plane is different when the cutting unit is in the second position than when the cutting unit is in the first position. The lawnmower comprises an actuator assembly configured to pivot the cutting unit relative to the lawnmower chassis so as to change the angle between the cutting plane and the first plane, wherein the actuator assembly is an electrical actuator assembly.

The angle between the cutting plane and a ground plane is a parameter of a lawnmower affecting the cutting result, the cutting efficiency, and the cutting resistance. A negative angle leads to poor cutting efficiency, poor cutting result, and a high cutting resistance. A negative angle of the cutting unit relative to a ground surface can be defined as an angle in which a trailing edge of the cutting unit is closer to the ground surface than a leading edge of the cutting unit. A negative angle impairs the cutting efficiency because substantially the entire cutting unit is subjected to grass during movement of the lawnmower which slows down the operation speed of the cutting unit. Moreover, most cutting units comprise cutting membersor cutting edges arranged at radial outer portions of the cutting unit. lf the angle between the cutting plane and a ground plane is negative, a radial centre portion of the cutting unit, which usually lacks cutting members or cutting edges, is also subjected to grass during movement of the lawnmower which increases the cutting resistance, reduces the cutting efficiency and reduces the cutting result.

The best cutting result is obtained if the angle between the cutting plane and a ground plane is close to zero but still on the positive side. A positive angle of the cutting unit relative to a ground surface can be defined as an angle in which the leading edge of the cutting unit is closer to the ground surface than the trailing edge of the cutting unit.

A positive angle helps keeping the operation speed of the cutting unit up and it will improve the energy efficiency of the lawnmower. This because the cutting members or cutting edges at the trailing edge of the cutting unit, and the radial centre portion of the cutting unit, will be located at a greater distance from the ground surface than the leading edge of the cutting unit and will thereby not be subjected to grass during movement of the lawnmower. However, if the angle is too big on the positive side, the cutting result may be affected to the negative. This because a large positive angle of the cutting unit relative to the ground surface may create a more curved cutting track. Curved cutting tracks may form visible cutting tracks in the lawn which impairs the cutting result.

The traditional way to solve the above mentioned issues is to arrange the cutting unit to have a built-in fixed positive angle of 2 - 5 degrees relative to the ground plane. Most often, a greater positive angle is selected than what is optimal in most operational conditions regarding the cutting result and the cutting efficiency. This because it may be wanted to avoid a negative angle in as many situations as possible.

Since the cutting unit of the lawnmower according to the present disclosure is pivotally arranged relative to the lawnmower chassis, a lawnmower is provided having conditions for a more advantageous angle betvveen the cutting plane and the ground plane at varying cutting conditions. Accordingly, a lawnmower is provided having conditions for an improved cutting result, an improved cutting efficiency, and a reduced cutting resistance at different cutting conditions. This because the cutting unit may be pivoted, manually or automatically, from the first position so as to obtain a more advantageous angle between the cutting plane and the ground plane at varying cutting conditions. Moreover, a lawnmower is provided having conditions for avoiding a negative angle between the cutting plane and the ground plane.

This because the cutting unit may be pivoted, manually or automatically, so as to avoid anegative angle between the cutting plane and the ground plane during operation of the lawnmower.

Since the lawnmower has conditions for a more advantageous angle between the cutting plane and the ground plane at varying cutting conditions, a lawnmower is provided having conditions for an improved energy efficiency at varying cutting conditions, which potentially prolongs the available operational time of the lawnmower. ln addition, since the cutting unit is pivotally arranged relative to the lawnmower chassis, a more durable lawnmower is provided. This because the cutting unit may pivot from the first position upon an impact between the cutting unit and an object, such as a stump, a stone, a sticks, or the like. Moreover, the cutting unit may pivot from the first position upon rough handling of the lawnmower, such as when a user carries the lawnmower and drops the lawnmower such that the cutting unit is hitting an object.

Since the lawnmower comprises an actuator assembly configured to pivot the cutting unit relative to the lawnmower chassis so as to change the angle between the cutting plane and the first plane, a lawnmower is provided in which the angle between the cutting plane and the first plane can be adjusted using the actuator assembly. For example, the angle between the cutting plane and the first plane can be adjusted based on cutting conditions and/or cutting requirements. That is, conditions are provided for a user, or a control arrangement, to select the angle between the cutting plane and the first plane based on cutting conditions, such as a length and/or density of vegetation of an area to be cut, and/or to select the angle between the cutting plane and the first plane based on cutting requirements, such cutting speed, cutting result, and/or energy consumption. As an example, if cutting speed and energy consumption are prioritized requirements, the angle between the cutting plane and the first plane can be adjusted to a greater positive angle, using the actuator assembly. As another example, if cutting result is the most prioritized requirement, the angle between the cutting plane and the first plane can be adjusted to a smaller positive angle, using the actuator assembly.

Moreover, since the lawnmower comprises the actuator assembly, the actuator assembly can be used to pivot the cutting assembly to obtain a more advantageous angle between the cutting plane and the first plane in the travelling direction of the lawnmower also when the lawnmower is travelling in a reverse direction of the lawnmower, for example by reducing the angle between the cutting plane and the first plane or by obtaining a positive angle in the travel direction when reversing the lawnmower.

Furthermore, since the lawnmower comprises the actuator assembly, the actuator assembly can be used to eliminate manufacturing tolerances affecting the angle betvveen the cutting plane and the first plane, for example in an assembling process of the lawnmower.

Moreover, since the actuator assembly is an electrical actuator assembly, a simple and efficient actuator assembly is provided having conditions for an automatic adaptation of the angle between the cutting plane and the first plane.

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

Optionally, the cutting plane is substantially parallel to the first plane when the cutting unit is in the first position. Thereby, a lawnmower is provided in which a great cutting result is obtained when the cutting unit is in the first position, while the cutting unit can be pivoted from the first position so as to obtain a more advantageous angle between the cutting plane and the ground plane at varying cutting conditions.

Optionally, the angle between the cutting plane and a longitudinal direction of the lawnmower is different when the cutting unit is in the second position than when the cutting unit is in the first position. Thereby, a lawnmower is provided having conditions for a more advantageous angle between the cutting plane and the longitudinal direction of the lawnmower at varying cutting conditions. Thereby, a lawnmower is provided having conditions for an improved cutting result, improved cutting efficiency, and reduced cutting resistance at different cutting conditions. This because the cutting unit may be pivoted, manually or automatically, from the first position so as to obtain a more advantageous angle between the cutting plane and the longitudinal direction of the lawnmower at varying cutting conditions.

Optionally, the cutting unit is configured to pivot from the first position based on a load exerted on the cutting unit by vegetation. As a result, the cutting unit can pivot from the first position to obtain a more advantageous angle relative to the ground plane based on the load exerted on the cutting unit by vegetation. When the lawnmower according to the present solution reaches a portion of a lawn having higher length and/or density of the vegetation, the load exerted on the cutting unit by vegetation will increase. Accordingly, a lawnmower is provided having conditions for obtaining a more advantageous angle between the cuttingplane and the ground plane in an automatic manner based on the length and density of the vegetation.

As a further result thereof, a lawnmower is provided having conditions for an improved energy efficiency at varying cutting conditions, which potentially prolongs the available operational time of the lawnmower.

Optionally, the cutting unit is configured to pivot from the first position by a reaction force obtained between the cutting unit and vegetation during operation of the lawnmower. As a result, the cutting unit can pivot from the first position to obtain a more advantageous angle relative to the ground plane by the reaction force obtained between the cutting unit and vegetation. When the lawnmower according to the present solution reaches a portion of a lawn having higher length and/or density of the vegetation, the reaction force obtained between the cutting unit and vegetation will increase. Accordingly, a lawnmower is provided having conditions for obtaining a more advantageous angle between the cutting plane and the ground plane in an automatic manner based on the length and density of the vegetation.

Moreover, since the cutting unit is configured to pivot from the first position by the reaction force obtained between the cutting unit and vegetation during operation of the lawnmower, the need for complex and costly arrangements is circumvented, such as sensors, motors, and the like, for adapting the angle of the cutting unit relative to the ground plane in an automatic manner at varying cutting conditions. Accordingly, a lawnmower is provided having conditions and characteristics suitable for being manufactured and assembled in a cost- efficient manner.

Optionally, the cutting unit is configured to pivot from the first position when a reaction force between the cutting unit and vegetation exceeds a predetermined threshold value during operation of the lawnmower. Thereby, a lawnmower is provided in which the cutting unit may be pivoted automatically from the first position when the reaction force between the cutting unit and vegetation exceeds the predetermined threshold value during operation of the lawnmower so as to obtain a more advantageous angle between the cutting plane and the ground plane. Accordingly, a lawnmower is provided having conditions for obtaining a more advantageous angle between the cutting plane and the ground plane in an automatic mannerbased on the length and density of the vegetation. Moreover, it can be ensured that the cutting unit is not pivoted from the first position when the reaction force between the cutting unit and the vegetation is below the predetermined threshold value during operation of the lawnmower. ln this manner, a more stable cutting unit is provided and unwanted movements between the cutting unit and the lawnmower chassis, such as wobbling of the cutting unit relative to the lawnmower chassis, can be avoided.

Furthermore, since a lawnmower is provided having conditions for obtaining a more advantageous angle between the cutting plane and the ground plane in an automatic manner based on the length and density of the vegetation, a lawnmower is provided having conditions for an improved energy efficiency at varying cutting conditions, which potentially prolongs the available operational time of the lawnmower.

Moreover, since the cutting unit is configured to pivot from the first position when a reaction force between the cutting unit and vegetation exceeds a predetermined threshold value during operation of the lawnmower, the need for complex and costly arrangements is circumvented, such as sensors, motors, and the like, for adapting the angle of the cutting unit relative to the ground plane in an automatic manner at varying cutting conditions. Accordingly, a lawnmower is provided having conditions and characteristics suitable for being manufactured and assembled in a cost-efficient manner.

Optionally, the lawnmower comprises at least one resilient element configured to bias the cutting unit towards the first position. Thereby, unwanted movements between the cutting unit and the lawnmower chassis, such as wobbling of the cutting unit, can be avoided, and a more stable cutting unit is provided.

Optionally, the lawnmower comprises at least one damper configured to damp movement between the cutting unit and the lawnmower chassis. Thereby, unwanted movements between the cutting unit and the lawnmower chassis, such as wobbling of the cutting unit, can be avoided, and a more stable cutting unit is provided.

Optionally, the cutting unit is pivotally arranged relative to the lawnmower chassis around a first pivot point, and wherein the first pivot point is arranged in front of a centre axis of the cutting unit seen in a forward direction of the lawnmower. Thereby, it can be ensured that the cutting unit can be pivoted from the first position to obtain a more advantageous angle between the cutting plane and the ground plane during movement of the lawnmower in the forward direction of the lawnmower. That is, since the first pivot point is arranged in front ofthe centre axis of the cutting unit seen in the forward direction of the lawnmower, the cutting unit is pivoted to obtain a more positive angle between the cutting plane and the ground plane when being pivoted from the first position. Accordingly, when the lawnmower is travelling in the fon/vard direction of the lawnmower and reaches a portion of a lawn having greater length and/or density of the vegetation, the reaction force between the cutting unit and the vegetation can apply can apply a torque onto the cutting unit which can displace the cutting unit from the first position towards a more positive angle relative to the ground plane.

When the angle of the cutting unit relative to the ground plane is positive, the leading edge of the cutting unit, seen in the fonNard direction of the lawnmower, is closer to the ground surface than the trailing edge of the cutting unit, seen in the fonNard direction of the lawnmower. ln this manner, a lowered cutting resistance is obtained which lowers the energy consumption of the lawnmower and potentially prolongs the available operational time of the lawnmower. ln addition, due to these features, a more constant cutting resistance can be obtained when mowing a lawn having varying length and/or density of the of the vegetation.

Moreover, due to these features, the risk of an obstruction of the cutting unit is reduced during operation of the lawnmower. This because the cutting resistance can be lowered when the lawnmower reaches a portion of a lawn having greater length and/or density of the vegetation, and because the risk of build-up of vegetation onto an area surrounding the cutting unit can be reduced.

Optionally, the first pivot point is arranged at a distance from the centre axis within the range of 0.5 to 1.5 times a radius of the cutting unit, or within the range of 0.8 to 1.2 times the radius of the cutting unit. Thereby, it can be ensured that an advantageous distance between the ground surface and the leading edge of the cutting unit, seen in the fon/vard direction of the lawnmower, is maintained when the cutting unit is pivoted from the first position.

Optionally, the vertical distance between the first pivot point and cutting members of the cutting unit is within the range of 15% - 60%, or 25% - 45% of a radius of the cutting unit. Thereby, it can be ensured that the cutting unit can be pivoted from the first position in a reliable and efficient manner to obtain a more advantageous angle between the cutting plane and the ground plane.

Optionally, the cutting unit is pivotally arranged relative to the lawnmower chassis around a second pivot point, and wherein the second pivot point is arranged behind a centre axis of the cutting unit seen in a forward direction of the lawnmower. Thereby, it can be ensured that the cutting unit can be pivoted from the first position to obtain a more advantageous angle between the cutting plane and the ground plane during movement of the lawnmower in a reverse direction of the lawnmower. That is, since the second pivot point is arranged behind the centre axis of the cutting unit seen in the forward direction of the lawnmower, the cutting unit is pivoted to obtain a more positive angle between the cutting plane and the ground plane when the lawnmower is trave||ing in the reverse direction and the cutting unit is pivoted around the second pivot point. That is, when the lawnmower is trave||ing in the reverse direction of the lawnmower and reaches a portion of a lawn having greater length and/or density of the vegetation, the reaction force between the cutting unit and the vegetation can apply can apply a torque onto the cutting unit which can displace the cutting unit towards a more positive angle relative to the ground plane seen in the reverse direction.

When the angle of the cutting unit relative to the ground plane is positive, the leading edge of the cutting unit, seen in the reverse direction of the lawnmower, is closer to the cutting unit than the trailing edge of the cutting unit, seen in the reverse direction of the lawnmower. ln this manner, a lowered cutting resistance can be obtained when the lawnmower moves in the reverse direction which lowers the energy consumption of the lawnmower and potentially prolongs the available operational time of the lawnmower. ln addition, due to these features, a more constant cutting resistance can be obtained when mowing a lawn having varying length and/or density of the of the vegetation.

Moreover, due to these features, the risk of an obstruction of the cutting unit is reduced during operation of the lawnmower. This because the cutting resistance can be lowered also when the lawnmower is trave||ing in the reverse direction and reaches a portion of a lawn having greater length and/or density of the vegetation, and because the risk of build-up of vegetation onto an area surrounding the cutting unit can be reduced.

Furthermore, since the cutting unit may be pivotally arranged relative to the lawnmower chassis around two pivot points, an even more durable lawnmower can be provided. This because the cutting unit may pivot also around the second pivot point upon an impact between the cutting unit and an object, such as a stump, a stone, a sticks, or the like. Moreover, the cutting unit may pivot also around the second pivot point upon rough handling of the lawnmower, such as when a user carries the lawnmower and drops the lawnmower such that the cutting unit is hitting an object.

A prior-art lawnmower having a built-in fixed positive angle of 2 - 5 degrees relative to the ground plane seen in the fon/vard direction obtains a negative angle of the same magnitude,i.e. of 2 - 5 degrees, between the cutting plane and the ground plane, seen in the reverse direction, when the lawnmower moves in the reverse direction. As a result thereof, such lawnmowers obtain a reduced cutting result, a reduced cutting efficiency, and an increased cutting resistance when moving in a reverse direction. However, since the second pivot point according to these embodiments of the lawnmower is arranged behind the centre axis of the cutting unit seen in the forward direction of the lawnmower, a negative angle between the cutting plane and the ground plane, seen in the reverse direction, can be avoided during reverse travel of the lawnmower. Moreover, due to these features, a lawnmower can be provided having the same advantageous positive angle between the cutting plane and the ground plane during movement in the reverse direction as when moving in the fonNard direction, which opens up the possibility of new designs of lawnmowers capable of operating equally good in both travel directions.

Optionally, the second pivot point is arranged at a distance from the centre axis within the range of 0.5 to 1.5 times a radius of the cutting unit, or within the range of 0.8 to 1.2 times the radius of the cutting unit. Thereby, it can be ensured that an advantageous distance between the ground surface and the leading edge of the cutting unit, seen in the reverse direction of the lawnmower, is maintained when the cutting unit is pivoted from the first position.

Optionally, the lawnmower comprises a holding member, wherein the cutting unit is pivotally arranged relative to the lawnmower chassis via the holding member, and wherein the holding member is configured to abut against a first seat when the cutting unit is in the first position, and is configured to be lifted from the first seat when the cutting unit is pivoted from the first position. Thereby, unwanted movements between the cutting unit and the lawnmower chassis, such as wobbling of the cutting unit, can be prevented, and a more stable cutting unit can be provided. ln addition, pivoting movement of the cutting unit from the first position in a direction away from the second position can be prevented. Moreover, a simple, efficient, and low-cost arrangement can be provided for arranging the cutting unit pivotally relative to the lawnmower chassis.

Optionally, the holding member is configured to abut against a second seat when the cutting unit is in the first position. Thereby, unwanted movements between the cutting unit and the lawnmower chassis, such as wobbling of the cutting unit, can be prevented, and a more stable cutting unit can be provided. ln addition, a distinct and precise first position of the cutting unit can be provided. Moreover, a simple, efficient, and low-cost arrangement can be provided for arranging the cutting unit pivotally relative to the lawnmower chassis.Optionally, the abutting contact between the holding member and the second seat forms the first pivot point. Thereby, a simple, efficient, and low-cost arrangement is provided for arranging the cutting unit pivotally relative to the lawnmower chassis.

Optionally, the abutting contact between the holding member and the first seat forms the second pivot point. Thereby, a simple, efficient, and low-cost arrangement is provided for arranging the cutting unit pivotally relative to the lawnmower chassis.

Optionally, the cutting unit is configured to be |ifted from the second seat when the cutting unit is pivoted around the second pivot point from the first position. Thereby, a simple, efficient, and low-cost arrangement is provided for arranging the cutting unit pivotally around two pivot points relative to the lawnmower chassis.

Optionally, the lawnmower comprises a driving unit configured to drive the cutting unit during operation of the lawnmower, and wherein the driving unit is arranged to pivot with the cutting unit. Thereby, the need for one or more components or arrangements capable of transferring power at different inc|ination angels, such as one or more universal joints, between the driving unit and the cutting unit is circumvented. Accordingly, a lawnmower is provided having conditions and characteristics suitable for being manufactured and assembled in a cost-efficient manner.

Optionally, the cutting unit comprises a cutting disc provided with a number of cutting members arranged at a periphery of the cutting disc. Thereby, an energy efficient cutting unit is provided capable of obtaining a more advantageous angle between the cutting plane and the ground plane during operation of the lawnmower.

Optionally, the cutting members are pivotally arranged to the cutting disc. Thereby, an energy efficient cutting unit is provided capable of obtaining a more advantageous angle between the cutting plane and the ground plane during operation of the lawnmower. Moreover, a lawnmower is provided with reduced risk of injury, and damage to the lawnmower, in case of an impact between a cutting member and an object.

Optionally, the lawnmower is a self-propelled autonomous robotic lawnmower. Thereby, robotic lawnmower is provided having conditions for a more advantageous angle between the cutting plane and the ground plane at varying cutting conditions. Accordingly, a robotic lawnmower is provided having conditions for an improved cutting result, improved cutting efficiency, and reduced cutting resistance at different cutting conditions. This because thecutting unit may be pivoted, manually or automatically, from the first position so as to obtain a more advantageous angle between the cutting plane and the ground plane at varying cutting conditions. Moreover, a robotic lawnmower is provided having conditions for avoiding a negative angle between the cutting plane and the ground plane. This because the cutting unit may be pivoted, manually or automatically, so as to avoid a negative angle between the cutting plane and the ground plane during operation of the robotic lawnmower.

Since the robotic lawnmower has conditions for a more advantageous angle between the cutting plane and the ground plane at varying cutting conditions, a robotic lawnmower is provided having conditions for an improved energy efficiency at varying cutting conditions, which potentially prolongs the available operational time of the robotic lawnmower. ln addition, since the cutting unit is pivotally arranged relative to the robotic lawnmower chassis, a more durable robotic lawnmower is provided. This because the cutting unit may pivot from the first position upon an impact between the cutting unit and an object, such as a stump, a stone, a sticks, or the like. Moreover, the cutting unit may pivot from the first position upon rough handling of the robotic lawnmower, such as when a user carries the robotic lawnmower and drops the robotic lawnmower such that the cutting unit is hitting an object.

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

Optionally, the lawnmower comprises an input unit and a control arrangement, and wherein the control arrangement is configured to control the actuator assembly to pivot the cutting unit to a set angle relative to the lawnmower chassis based on data from the input unit. Thereby, a lawnmower is provided capable of adapting the angle between the cutting plane and the first plane in an automatic manner based on data from the input unit. ln this manner, a more advantageous angle between the cutting plane and the ground plane can be obtained in an automatic manner at varying cutting conditions.

According to some embodiments, the input unit allows input from a user. That is, according to some embodiments, the input unit allows a user to select a wanted angle between the cutting plane and the first plane, or allows a user to select between different modes or programs representing different priorities between requirements such as cutting speed,energy consumption, and cutting result. ln this manner, a more user friendly lawnmower is provided having conditions for an improved cutting result, an improved cutting efficiency, and a reduced cutting resistance at different cutting conditions.

Optionally, the input unit is configured to obtain data representative of a current position of the lawnmower, and wherein the control arrangement is configured to determine the set angle based on the current position of the lawnmower. Thereby, a lawnmower is provided capable of adapting the angle between the cutting plane and the first plane based on the position of the lawnmower. ln this manner, conditions are provided for cutting some areas of a lawn faster using less energy and cutting some other areas of the lawn with a higher cutting result. ln this manner, a lawn can be divided into different areas having different demands on lawn appearance and cutting result. As an example, a user may select an area of a lawn close to a house as a first area and an area of a lawn remote from the house as a second area. The second area may for example be an area of the lawn normally hidden by shrubs, trees, garden furniture, or the like. The control arrangement may then control the actuator assembly to obtain a small positive angle when the lawnmower is in the first area and may control the actuator assembly to obtain a greater positive angle when the lawnmower is in the second area. ln this manner, the first area is cut with higher precision, i.e. with a higher cutting result, than the second area, and the second area is cut with a lower cutting resistance than the first area, i.e. with a reduced energy consumption. ln addition, due to the greater positive angle, the second area can be cut faster.

Optionally, the input unit is configured to obtain data representative of a current cutting resistance, and wherein the control arrangement is configured to determine the set angle based on the current cutting resistance. Thereby, a lawnmower is provided capable of adapting the angle between the cutting plane and the first plane in an automatic manner based on the cutting resistance. As understood from the herein described, the cutting resistance increases with increased length and density of the vegetation being cut. Moreover, the cutting resistance increases with increased travel speed of the lawnmower. According to some embodiments, the control arrangement may be configured to increase the angle between the cutting plane and the first plane with increased cutting resistance and may be configured to decrease the angle between the cutting plane and the first plane with decreased cutting resistance. ln this manner, the angle between the cutting plane and the first plane can be adjusted in an automatic manner based on the length and density of the vegetation being cut and based on the travel speed of the lawnmower. ln this manner, a good compromise can be provided between lawn appearance and cutting efficiency at all times and at varying cutting conditions.

Optionally, the lawnmower comprises an electric motor configured to drive the cutting unit during operation of the lawnmower, and wherein the input unit is configured to obtain data representative of the current cutting resistance by monitoring electrical quantities of the electric motor. Thereby, the cutting resistance is obtained in a simple, reliable, and cost- efficient manner.

According to a second aspect of the invention, the cutting unit is movably arranged relative to the lawnmower chassis to move between a first position and a second position. The distance between at least a portion of the cutting unit and the first plane is different when the cutting unit is in the second position than when the cutting unit is in the first position. The cutting unit is configured to move from the first position to the second position by a reaction force obtained between the cutting unit and vegetation during operation of the lawnmower.

Since the cutting unit is configured to move from the first position to the second position by a reaction force obtained between the cutting unit and vegetation during operation of the lawnmower, a lawnmower is provided capable of obtaining a more advantageous distance between at least a portion of the cutting unit and the ground plane by the reaction force obtained between the cutting unit and vegetation during operation of the lawnmower. ln this manner, a lawnmower is provided having conditions for an improved cutting result, an improved cutting efficiency, and a reduced cutting resistance at different cutting conditions. That is, when the lawnmower according to the present solution reaches a portion of a lawn having higher length and/or density of the vegetation, the reaction force obtained between the cutting unit and vegetation will increase. Since the cutting unit is configured to move from the first position to the second position by the reaction force obtained between the cutting unit and vegetation during operation of the lawnmower, a lawnmower is provided capable of obtaining a more advantageous distance between at least a portion of the cutting unit and the ground plane in an automatic manner based on the current length and/or density of the vegetation.

As a further result thereof, a lawnmower is provided having conditions for an improved energy efficiency at varying cutting conditions, which potentially prolongs the available operational time of the lawnmower. ln addition, since the cutting unit is movably arranged relative to the lawnmower chassis, a more durable lawnmower is provided. This because the cutting unit may move from the firstposition upon an impact between the cutting unit and an object, such as a stump, a stone, a sticks, or the like. Moreover, the cutting unit may move from the first position upon rough handling of the lawnmower, such as when a user carries the lawnmower and drops the lawnmower such that the cutting unit is hitting an object.

The lawnmower according to the second aspect of the invention is combinable with any one of the features of the lawnmower according to the first aspect of the invention explained herein. That is, the lawnmower according to the second aspect of the invention may comprise one or more of the features of the lawnmower according to the first aspect of the invention explained herein. In other words, the lawnmower according to the second aspect of the invention may comprise the same features, functions, and advantages as the lawnmower according to the first aspect of the invention explained herein.

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 DRAWINGS Various aspects of the invention, including its particular features and advantages, will be readily understood from the example embodiments discussed in the following detailed description and the accompanying drawings, in which: Fig. 1 schematically illustrates a lawnmower according to some embodiments of the present disclosure, Fig. 2 schematically illustrates a chassis member of the lawnmower illustrated in Fig. 1, Fig. 3 illustrates the chassis member illustrated in Fig. 2 with a cutting unit in a second position, Fig. 4 illustrates the chassis member illustrated in Fig. 2 and Fig. 3 with the cutting unit in a third position, Fig. 5 schematically illustrates a chassis member, according to some further embodiments, of a lawnmower, and Fig. 6 illustrates a lawnmower, according to some embodiments, illustrated as mowing a lawn.

DETAILED DESCRIPTION Aspects of the present invention will now be described more fully. Like numbers refer to like elements throughout. Well-known functions or constructions will not necessarily be described in detail for brevity and/or clarity.Fig. 1 schematically illustrates a lawnmower 1 according to some embodiments of the present disclosure. According to the illustrated embodiments, the lawnmower 1 is a self- propelled autonomous robotic lawnmower 1 capable of navigating and cutting grass in an autonomous manner in an area without the intervention or the control of a user. For the reason of brevity and clarity, the self-propelled autonomous robotic lawnmower 1 is in some places herein referred to as “the robotic lawnmower 1" or simply the “lawnmower 1". According to the illustrated embodiments, the robotic lawnmower 1 is configured to be used to cut grass in areas 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 chassis 3 and a number of lawnmower support members 5, 5' each configured to abut against a ground surface 7 in a first plane P1 during operation of the lawnmower 1. Accordingly, the first plane P1 will extend along a ground surface 7 when the lawnmower 1 is positioned on a flat ground surface 7. According to the illustrated embodiments, the lawnmower support members 5, 5' is wheels 5, 5' of the lawnmower 1. According to the illustrated embodiments, the lawnmower 1 comprises four wheels 5, 5', namely two drive wheels 5 and two support wheels 5'. The drive wheels 5 of the lawnmower 1 may each be powered by an electrical motor of the lawnmower 1 to provide motive power and/or steering of the lawnmower 1. ln Fig. 1, a longitudinal direction ld of the lawnmower 1 is indicated. The longitudinal direction ld of the lawnmower 1 extends in a longitudinal plane LP of the lawnmower 1. The longitudinal plane LP is parallel to the first plane P1. The longitudinal direction ld of the lawnmower 1 is thus parallel to the first plane P1 and thus also to a ground surface 7 when the lawnmower 1 is positioned onto a flat ground surface 7. Moreover, the longitudinal direction ld of the lawnmower 1 is parallel to a forward direction fd of travel of the lawnmower 1 as well as a reverse direction rd of travel of the lawnmower 1, as is further explained herein.

According to the illustrated embodiments, the drive wheels 5 of the lawnmower 1 are non- steered wheels having a fix rolling direction in relation to the lawnmower chassis 3. The respective rolling direction of the drive wheels 5 of the lawnmower 1 is substantially parallel to the longitudinal direction ld of the lawnmower 1. According to the illustrated embodiments, the support wheels 5' are non-driven wheels. Moreover, according to the illustrated embodiments, the support wheels 5' can pivot around a respective pivot axis such that the rolling direction of the respective support wheel 5' can follow a travel direction of the lawnmowerAs understood from the above, when the drive wheels 5, 5' of the lawnmower 1 are rotated at the same rotational velocity in a forward rotational direction, and no wheel slip is occurring, the lawnmower 1 will move in the fonNard direction fd indicated in Fig. 1. Likewise, when the drive wheels 5, 5' of the lawnmower 1 are rotated at the same rotational velocity in a reverse rotational direction, and no wheel slip is occurring, the lawnmower 1 will move in the reverse direction rd indicated in Fig. 1. The reverse direction rd is opposite to the fonNard direction fd.

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 lawnmower 1 may be provided with another number of wheels 5, 5', such as three wheels. Moreover, according to further embodiments, the lawnmower 1 may be provided with another configuration 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 arrangement 2. The control arrangement 2 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 to drive the drive wheels 5 of the lawnmower 1. According to further embodiments, the control arrangement 2 may be configured to steer the lawnmower 1 by contro||ing the angle of steered wheels of the lawnmower 1. According to still further embodiments, the robotic tool may be an articulated robotic tool, wherein the control arrangement 2 may be configured to steer the robotic tool by contro||ing the angle between frame portions of the articulated robotic tool.

The control arrangement 2 may be configured to control propulsion of the lawnmower 1, and steer the lawnmower 1, so as to navigate the lawnmower 1 in an area to be operated. The lawnmower 1 may further comprise one or more sensors arranged to sense a magnetic field of a wire, and/or one or more positioning units, and/or one or more sensors 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 arrangement 2. The communication unit may be configured to communicate with a remote communication unit to receive instructions therefrom and/or to send information thereto. The communication may be performed wirelessly over a wireless connection such as the internet, or a wireless local area network (WLAN), or a wireless connection for exchanging data over short distances using short-wavelength, i.e. ultra-high frequency (UHF) radio waves in the industrial, scientific, and medical (ISM) band from 2.4 to 2.485 GHz.The control arrangement 2 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/or random pattern to ensure that an area is completely covered, using input from one or more of the above described sensors and/or units. Furthermore, the lawnmower 1 may comprise one or more batteries arranged to supply electricity to components of the lawnmower 1. As an example, 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 The lawnmower 1 comprises a cutting unit 9. The cutting unit 9 is configured to operate in a cutting plane PC. According to the illustrated embodiments, the cutting unit 9 is configured to rotate in the cutting plane PC around a rotation axis ra. The rotation axis ra is perpendicular to the cutting plane PC.

The cutting unit 9 is pivotally arranged relative to the lawnmower chassis 3 to pivot between a first position and a second position. ln Fig. 1, the cutting unit 9 is illustrated in the first position. As is further explained herein, the angle between the cutting plane PC and the first plane P1 is different when the cutting unit 9 is in the second position than when the cutting unit 9 is in the first position.

Fig. 2 schematically illustrates a chassis member 3' of the lawnmower 1 illustrated in Fig. 1. The embodiments of the chassis member 3' explained with reference to Fig. 2 - Fig. 4 comprise an actuator assembly configured to pivot the cutting unit 9 relative to the lawnmower chassis 3, as explained with reference to Fig. 5 and Fig. 6. As can be seen in Fig. 2, the chassis member 3' comprises the cutting unit 9 and a driving unit 17 configured to rotate the cutting unit 9 around the rotation axis ra of the cutting unit 9 during operation of the lawnmower 1. The driving unit 17 may comprise an electric motor 17. As indicated in Fig. 2, according to the illustrated embodiments, the rotation axis ra of the cutting unit 9 corresponds to a centre axis ca of the cutting unit 9. The chassis member 3' is stationary arranged relative to the lawnmower chassis 3 indicated in Fig. 1 during operation of the lawnmower 1. However, according to some embodiments, the lawnmower 1 may comprise an adjustment mechanism via which a user can adjust the mounting position of the chassis member 3' relative to the lawnmower chassis 3 indicated in Fig. 1 so as to adjust the distance between the cutting plane PC of the cutting unit 9 and the first plane P According to the illustrated embodiments, the cutting unit 9 comprises a cutting discprovided with a number of cutting members 22 arranged at a periphery 20' of the cutting disc . Moreover, according to the illustrated embodiments, the cutting members 22 are pivotally arranged to the cutting disc 20. The cutting members 22 comprise sharp cutting edges configured to cut vegetation, such as grass, during rotation of the cutting unit ln Fig. 2, the cutting unit 9 is illustrated in the first position. As can be seen in Fig. 2, as well as in Fig. 1, according to the illustrated embodiments, the cutting plane PC is substantially parallel to the first plane P1 when the cutting unit 9 is in the first position. However, according to further embodiments, the first position, as referred to herein, may constitute a position in which the cutting plane PC is angled relative to the first plane P1, for example by an angle within the range of zero to five degrees.

Fig. 3 illustrates the chassis member 3' illustrated in Fig. 2 with the cutting unit 9 in a second position. The “second position” as referred to herein may not be a particular distinct position of the cutting unit 9, such as an end position of the cutting unit 9. lnstead, the “second position” as referred to herein may be any other position of the cutting unit 9 different from the first position of the cutting unit 9, as referred to herein.

As is evident when comparing Fig. 3 and Fig. 2, the angle between the cutting plane PC and a longitudinal direction ld of the lawnmower 1 is different when the cutting unit 9 is in the second position than when the cutting unit 9 is in the first position.

According to the illustrated embodiments, the cutting unit 9 is configured to pivot from the first position based on a load exerted on the cutting unit 9 by vegetation. The load exerted on the cutting unit 9 by vegetation depends on a current length and/or density of the vegetation being cut by the cutting unit 9, as well as on a travel speed of the lawnmower 1. ln Fig. 3, the chassis member 3' is illustrated in a situation in which the lawnmower 1 is travelling in the fonNard direction fd indicated in Fig. 1 - Fig. 3. The cutting unit 9 is configured to pivot from the first position to the second position by a reaction force obtained between the cutting unit 9 and vegetation during operation of the lawnmower According to the illustrated embodiments, the cutting unit 9 is pivotally arranged relative to the lawnmower chassis 3 around a first pivot point pp1, wherein the first pivot point pp1 is arranged in front of a centre axis ca of the cutting unit 9 seen in a fonNard direction fd of the lawnmower 1. Moreover, the first pivot point pp1 is arranged such that the cutting plane PC is located between the first pivot point pp1 and the first plane P1. Furthermore, according to the illustrated embodiments, the first pivot point pp1 is arranged at a distance d1 from the centre axis ca of the cutting unit 9 substantially corresponding to the radius r of the cutting unitThe distance d1 is measured in a plane parallel to the cutting plane PC. The radius r of the cutting unit 9 is measured in the cutting plane PC from the centre axis ca of the cutting unit 9 to a radial outer periphery 9' of the cutting unit 9. According to the illustrated embodiments, the radial outer periphery 9' of the cutting unit 9 corresponds to a radial outer periphery of the cutting members 22. According to further embodiments, the first pivot point pp1 may be arranged at a distance d1 from the centre axis ca within the range of 0.5 to 1.5 times the radius r of the cutting unit 9, or within the range of 0.8 to 1.2 times the radius r of the cutting unit 9. According to the illustrated embodiments, the cutting unit 9 is configured to pivot around the first pivot point pp1 based on the load exerted on the cutting unit 9 by vegetation when the lawnmower 1 is trave||ing in the forward direction fd.

Due to these features, the cutting unit 9 will be moved from the first position to the second position by a reaction force obtained between the cutting unit 9 and vegetation during operation of the lawnmower 1 when the lawnmower 1 is trave||ing in the forward direction fd. According to the illustrated embodiments, the movement of the cutting unit 9 will constitute a pivoting movement of the cutting unit 9 around the first pivot point pp1. Accordingly, due to these features, a lawnmower 1 is provided capable of adapting the angle of the cutting unit 9 in relation to the first plane based on a current length and/or density of the vegetation being cut.

As can be seen when comparing Fig. 2 and Fig. 3, a distance D1 between a leading edge of the cutting unit 9 and the first plane P1 is substantially the same when the cutting unit 9 is in the second position as compared to when the cutting unit 9 is in the first position. This is due to the fact that, according to the illustrated embodiments, the first pivot point pp1 is arranged at a distance d1 from the centre axis ca of the cutting unit 9 substantially corresponding to the radius r of the cutting unit 9. Since the distance D1 between the leading edge of the cutting unit 9 and the first plane P1 is substantially the same when the cutting unit 9 is in the second position as compared to when the cutting unit 9 is in the first position, the cutting height of the lawnmower1 can be maintained also when the cutting unit 9 is in the second position.

Moreover, as can be seen when comparing Fig. 2 and Fig. 3, the distance D2 between the trailing edge 9' of the cutting unit 9 and the first plane P1 is greater when the cutting unit 9 is in the second position than when the cutting unit 9 is in the first position. Likewise, the distance between other portions of the cutting unit 9 and the first plane P1, such as a centre portion of the cutting unit 9, is greater when the cutting unit 9 is in the second position than when the cutting unit 9 is in the first position. Thereby, a lowered cutting resistance isobtained when the cutting unit 9 is in the second position. Accordingly, due to these features, a lawnmower 1 is provided capable of adapting the cutting resistance based on a current length and/or density of the vegetation being cut.

According to the illustrated embodiments, the lawnmower 1 comprises a holding member 15. The cutting unit 9 is pivotally arranged relative to the lawnmower chassis 3 via the holding member 15. As can be seen in Fig. 1, the holding member 15 is configured to abut against a first seat s1 when the cutting unit 9 is in the first position. Moreover, as can be seen in Fig. 2, the holding member 15 is configured to be lifted from the first seat s1 when the cutting unit 9 is pivoted from the first position. Furthermore, as can be seen in Fig. 2, the driving unit 17 is arranged to pivot with the cutting unit According to the illustrated embodiments, the lawnmower 1 comprises two resilient elements 11, 12 each configured to bias the cutting unit 9 towards the first position. According to further embodiments, the lawnmower 1 may comprise at least one resilient element 11, 12 configured to bias the cutting unit 9 towards the first position. According to the illustrated embodiments, the resilient elements 11, 12 applies a biasing force onto the holding member such that the holding member 15 is pressed towards the first seat s1. According to the illustrated embodiments, the resilient elements 11, 12 each comprises a coil spring. According to further embodiments, the resilient elements 11, 12 may each comprise another type of resilient element, such as a rubber element, a leaf spring, or the like.

Due to these features, according to the illustrated embodiments, the cutting unit 9 is configured to pivot from the first position when a reaction force between the cutting unit 9 and vegetation exceeds a predetermined threshold value during operation of the lawnmower 1. That is, if the reaction force between the cutting unit 9 and vegetation is below a predetermined threshold value, the holding member 15 will remain in abutting contact with the first seat 15. The predetermined threshold value is determined by spring coefficients of the resilient elements 11, 12, the location of the first pivot point pp1 in relation to the cutting plane PC, the location of the first pivot point pp1 in relation to the leading edge of the cutting unit 9, the weight of the pivoting parts of the chassis member 3', and gyroscopic effects of rotating parts of the chassis member 3”. The predetermined threshold value may be determined to a value ensuring that the cutting unit 9 is pivoted from the first position when it provides positive effects on the cutting resistance, the cutting result, and/or the cutting efficiency of the lawnmowerAccording to the illustrated embodiments, the lawnmower 1 comprises a damper 13. Due to the damper 13, a more stable cutting unit 9 is provided and unwanted movements between the cutting unit 9 and the lawnmower chassis 3', such as wobbling of the cutting unit 9 relative to the lawnmower chassis 3', can be avoided. The damper 13 is configured to damp movement between the cutting unit 9 and the lawnmower chassis 3 by damping movement between the holding member 15 and the chassis member 3”. ln Fig. 2 and Fig. 3, only one damper 13 is illustrated. However, the lawnmower 1 may comprise more than one damper 13, for example including one damper arranged at the resilient element 12 provided with the reference sign “12” in Fig. 2 and Fig.

As can be seen in Fig. 2, the holding member 15 is configured to abut against a second seat s2 when the cutting unit 9 is in the first position. Moreover, as seen in Fig. 3, the abutting contact between the holding member 15 and the second seat s2 forms the first pivot point pp According to the illustrated embodiments, the vertical distance vd1, indicated in Fig. 2, between the first pivot point pp1 and the cutting members 22 of the cutting unit 20 is approximately 25% of the radius r of the cutting unit 9. According to further embodiments, the vertical distance vd1 between the first pivot point pp1 and cutting members 22 of the cutting unit 20 may be within the range of 15% - 90%, or 25% - 45% of the radius r of the cutting unit 9. ln this manner, it can be ensured that the cutting unit 9 can be pivoted from the first position in a reliable and efficient manner.

As is further explained herein, according to the illustrated embodiments, the cutting unit 9 is pivotally arranged relative to the lawnmower chassis 3 around a second pivot point pp2. The second pivot point pp2 is arranged behind the centre axis ca of the cutting unit 9 seen in the fonNard direction fd of the lawnmower Fig. 4 illustrates the chassis member 3' illustrated in Fig. 2 and Fig. 3 with the cutting unit 9 in a third position. The “third position” as referred to herein may not be a particular distinct position of the cutting unit 9, such as an end position of the cutting unit 9. lnstead, the “third position” as referred to herein may be any other position of the cutting unit 9 different from the first position of the cutting unit 9, as referred to herein.

As is evident when comparing Fig. 4 and Fig. 2, the angle between the cutting plane PC and a longitudinal direction ld of the lawnmower 1 is different when the cutting unit 9 is in the third position than when the cutting unit 9 is in the first position.ln Fig. 4, the chassis member 3' is illustrated in a situation in which the lawnmower 1 is travelling in the reverse direction rd indicated in Fig. 1 - Fig. 4. The cutting unit 9 is configured to pivot around the second pivot point pp2 from the first position towards the third position by a reaction force obtained between the cutting unit 9 and vegetation during operation of the lawnmower 1 in the reverse direction rd.

Moreover, the second pivot point pp2 is arranged such that the cutting plane PC is located between the second pivot point pp2 and the first plane P1. Furthermore, according to the illustrated embodiments, the second pivot point pp2 is arranged at a distance d2 from the centre axis ca of the cutting unit 9 substantially corresponding to the radius r of the cutting unit 9. The distance d2 is measured in a plane parallel to the cutting plane PC. According to further embodiments, the second pivot point pp2 may be arranged at a distance d2 from the centre axis ca within the range of 0.5 to 1.5 times the radius r of the cutting unit 9, or within the range of 0.8 to 1.2 times the radius r of the cutting unit Due to these features, the cutting unit 9 will be moved from the first position towards the third position by a reaction force obtained between the cutting unit 9 and vegetation during operation of the lawnmower 1 when the lawnmower 1 is travelling in the reverse direction rd. According to the illustrated embodiments, the movement of the cutting unit 9 will constitute a pivoting movement of the cutting unit 9 around the second pivot point pp As can be seen when comparing Fig. 2 and Fig. 4, a distance D2 between a leading edge 9' of the cutting unit 9 and the first plane P1 is substantially the same when the cutting unit 9 is in the third position as compared to when the cutting unit 9 is in the first position. This is due to the fact that, according to the illustrated embodiments, the second pivot point pp2 is arranged at a distance d2 from the centre axis ca of the cutting unit 9 substantially corresponding to the radius r of the cutting unit 9. Since the distance D2 between the leading edge 9' of the cutting unit 9 and the first plane P1 is substantially the same when the cutting unit 9 is in the second position as compared to when the cutting unit 9 is in the first position, the cutting height of the lawnmower1 can be maintained also when the cutting unit 9 is in the third position.

As can be seen in Fig. 4, the abutting contact between the holding member 15 and the first seat s1 forms the second pivot point pp2. Moreover, as can be seen in Fig. 4, the cutting unit 9 is configured to be lifted from the second seat s2 when the cutting unit 9 is pivoted around the second pivot point pp2 from the first position.

The cutting unit 9 may be configured to pivot from the first position towards the third position when a reaction force between the cutting unit 9 and vegetation exceeds a predetermined threshold value during operation of the lawnmower in the reverse direction rd. The predetermined threshold value may have the same magnitude as the predetermined threshold value explained with reference to Fig.

The following will be explained with simultaneous reference to Fig. 1 - Fig. 4. As is explained herein, the angle between the cutting plane PC and the first plane P1 is a parameter of a lawnmower 1 affecting the cutting result, the cutting efficiency, and the cutting resistance. A negative angle leads to poor cutting efficiency, poor cutting result, and a high cutting resistance. A negative angle of the cutting unit 9 relative to the first plane P1 can be defined as an angle in which a trailing edge of the cutting unit 9 is closer to the first plane P1 than a leading edge of the cutting unit 9 seen in the moving direction fd, rd of the lawnmower 1. A negative angle impairs the cutting efficiency because substantially the entire cutting unit 9 is subjected to grass during movement of the lawnmower 1 which slows down the operation speed of the cutting unit 9. lf the angle between the cutting plane PC and a first plane P1 is negative, a radial centre portion of the cutting unit 9, which usually lacks cutting members 22, is also subjected to grass during movement of the lawnmower 1 which increases the cutting resistance, reduces the cutting efficiency and reduces the cutting result.

A positive angle of the cutting unit 9 relative to a first plane P1 can be defined as an angle in which the leading edge of the cutting unit 9 is closer to the first plane P1 than the trailing edge of the cutting unit 9 seen in the moving direction fd, rd of the lawnmower 1. A positive angle helps keeping the operation speed of the cutting unit 9 up and it will improve the energy efficiency of the lawnmower 1. This because the cutting members 22 or cutting edges at the trailing edge of the cutting unit 9, and the radial centre portion of the cutting unit 9, will be located at a greater distance from the first plane P1 than the leading edge of the cutting unit 9 and will thereby not be subjected to grass during movement of the lawnmower 1. However, if the angle is too big on the positive side, the cutting result may be affected to the negative. This because a large positive angle of the cutting unit 9 relative to the first plane P1 may create a more curved cutting track. Curved cutting tracks may form visible cutting tracks in the lawn which impairs the cutting result.

The traditional way to solve the above mentioned issues is to arrange the cutting unit 9 to have a built-in fixed positive angle of 2 - 5 degrees relative to the first plane P1. Most often, a greater positive angle is selected than what is optimal in most operational conditionsregarding the cutting result and the cutting efficiency. This because it may be wanted to avoid a negative angle in as many situations as possible.

Since the cutting unit 9 of the lawnmower 1 according to the present disclosure is pivotally arranged relative to the lawnmower 1 chassis, a lawnmower 1 is provided having conditions for a more advantageous angle between the cutting plane PC and the first plane P1 at varying cutting conditions. Accordingly, a lawnmower 1 is provided having conditions for an improved cutting result, an improved cutting efficiency, and a reduced cutting resistance at different cutting conditions. This because the cutting unit 9 may be pivoted from the first position so as to obtain a more advantageous angle between the cutting plane PC and the first plane P1 at varying cutting conditions. Moreover, a lawnmower 1 is provided having conditions for avoiding a negative angle between the cutting plane PC and the first plane P1. This because the cutting unit 9 may be pivoted so as to avoid a negative angle between the cutting plane PC and the first plane P1 during operation of the lawnmower Since the lawnmower 1 has conditions for a more advantageous angle between the cutting plane PC and the first plane P1 at varying cutting conditions, a lawnmower1 is provided having conditions for an improved energy efficiency at varying cutting conditions, which potentially prolongs the available operational time of the lawnmower ln addition, since the cutting unit 9 is pivotally arranged relative to the lawnmower 1 chassis, a more durable lawnmower 1 is provided. This because the cutting unit 9 may pivot from the first position upon an impact between the cutting unit 9 and an object, such as a stump, a stone, a sticks, or the like. Moreover, the cutting unit 9 may pivot from the first position upon rough handling of the lawnmower 1, such as when a user carries the lawnmower 1 and drops the lawnmower 1 such that the cutting unit 9 is hitting an object.

Since the second pivot point pp2 is arranged behind the centre axis of the cutting unit 9 seen in the forward direction fd of the lawnmower 1, the cutting unit 9 is pivoted to obtain a more positive angle between the cutting plane PC and the first plane P1 when the lawnmower 1 is travelling in the reverse direction rd and the cutting unit 9 is pivoted around the second pivot point pp2. That is, when the lawnmower 1 is travelling in the reverse direction rd of the lawnmower 1 and reaches a portion of a lawn having greater length and/or density of the vegetation, the reaction force between the cutting unit 9 and the vegetation can apply can apply a torque onto the cutting unit 9 which can displace the cutting unit 9 towards a more positive angle relative to the first plane P1 seen in the reverse direction rd. Likewise, when the lawnmower 1 is travelling in the forward direction fd of the lawnmower 1 and reaches aportion of a lawn having greater length and/or density of the vegetation, the reaction force between the cutting unit 9 and the vegetation can apply can apply a torque onto the cutting unit 9 which can displace the cutting unit 9 towards a more positive angle relative to the first plane P1 seen in the fonNard direction fd.

When the angle of the cutting unit 9 relative to the first plane P1 is positive, the leading edge of the cutting unit 9, seen in the reverse direction rd of the lawnmower 1, is closer to the cutting unit 9 than the trailing edge of the cutting unit 9, seen in the moving direction fd, rd of the lawnmower 1. ln this manner, a lowered cutting resistance can be obtained in in the moving direction fd, rd which lowers the energy consumption of the lawnmower 1 and potentially prolongs the available operational time of the lawnmower 1. ln addition, due to these features, a more constant cutting resistance can be obtained when mowing a lawn having varying length and/or density of the of the vegetation.

Moreover, due to these features, a lawnmower 1 is provided capable of obtaining the same advantageous positive angle between the cutting plane PC and the first plane P1 during movement in the reverse direction rd as when moving in the fonNard direction fd. Accordingly, a lawnmower 1 is provided capable of operating equally good in both travel directions fd, rd.

Furthermore, too big positive angles between the cutting plane PC and the first plane P1 can be avoided due to the at least one resilient element 11, 12 being configured to bias the cutting unit 9 towards the first position.

According to some embodiments of the present disclosure, the first pivot point pp1 may be arranged in front of the leading edge of the cutting unit 9 seen in the forward direction fd. Purely as examples, according to such embodiments, the first pivot point pp1 may be arranged at a distance d1 from the centre axis ca within the range of 1.05 to 2 times the radius r of the cutting unit 9, or within the range of 1.1 to 1.7 times the radius r of the cutting unit 9. Likewise, the second pivot point pp2 may be arranged in front of the leading edge of the cutting unit 9 seen in the reverse direction rd. Purely as examples, according to such embodiments, the second pivot point pp2 may be arranged at a distance d2 from the centre axis ca within the range of 1.05 to 2 times the radius r of the cutting unit 9, or within the range of 1.1 to 1.7 times the radius r of the cutting unit 9. According to such embodiments, the distance D1, D2 between the leading edge of the cutting unit 9 and the first plane P1 can be greater when the cutting unit 9 is in a second or third position as compared to when the cutting unit 9 is in the first position.Fig. 5 schematically illustrates a chassis member 3' according to some further embodiments of a lawnmower. The lawnmower may be a lawnmower 1 according to the embodiments illustrated in Fig. 1. The chassis member 3' illustrated in Fig. 5 comprises the same features, functions, and advantages as the chassis member 3' explained with reference to Fig. 2 - Fig. 4, with some differences explained below.

As illustrated in Fig. 5, the lawnmower 1 comprises an actuator assembly 31 configured to pivot the cutting unit 9 relative to the lawnmower chassis 3 so as to change the angle between the cutting plane PC and the first plane P According to the illustrated embodiments, the holding member 15 of the chassis member 3' is hinged at a pivot point pp1. ln this manner, the cutting unit 9 is pivotally arranged relative to the lawnmower chassis 3 around the pivot point pp1. The pivot point pp1 is arranged in front of a centre axis ca of the cutting unit 9 seen in a forward direction fd of the lawnmower 1. Moreover, the pivot point pp1 is arranged such that the cutting plane PC is located between the pivot point pp1 and the first plane P1. Furthermore, according to the illustrated embodiments, the pivot point pp1 is arranged at a distance d1 from the centre axis ca of the cutting unit 9 substantially corresponding to the radius r of the cutting unit 9. The distance d1 is measured in a plane parallel to the cutting plane PC. The radius r of the cutting unit 9 is measured in the cutting plane PC from the centre axis ca of the cutting unit 9 to a radial outer periphery 9' of the cutting unit 9. According to the illustrated embodiments, the radial outer periphery 9' of the cutting unit 9 corresponds to a radial outer periphery of the cutting members 22 of the cutting unit 9. According to further embodiments, the pivot point pp1 may be arranged at a distance d1 from the centre axis ca within the range of 0.5 to 1.5 times the radius r of the cutting unit 9, or within the range of 0.8 to 1.2 times the radius r of the cutting unit As understood from the above, the actuator assembly 31 is configured to pivot the cutting unit 9 relative to the lawnmower chassis 3 around the pivot point pp1 so as to change the angle between the cutting plane PC and the first plane P1. ln Fig. 5, the cutting unit 9 is illustrated in a position in which the cutting plane PC is parallel to the first plane P1. The actuator assembly 31 may thus pivot the cutting unit 9 around the pivot point pp1 to obtain a positive angle of the cutting plane PC relative to the first plane P1, seen in the forward direction fd of the lawnmower indicated in Fig. 5. Moreover, according to the illustrated embodiments, the actuator assembly 31 can also pivot the cutting unit 9 around the pivot point pp1 to obtain a negative angle of the cutting plane PC relative to the first plane P1,seen in the forward direction fd of the lawnmower. This can be advantageous when mowing in a reverse direction rd of the lawnmower, as is further explained herein. However, according to further embodiments, the actuator assembly 31 may only be able to pivot the cutting unit 9 around the pivot point pp1 to obtain positive angles of the cutting plane PC relative to the first plane P1, seen in the fonNard direction fd of the lawnmower. According to such embodiments, the chassis member 3' may comprise a stop surface preventing pivoting of the holding member 15 to positions in which a negative angle is obtained between the cutting plane PC relative to the first plane P1, seen in the forward direction fd of the lawnmower.

According to the illustrated embodiments, the actuator assembly 31 is a linear electrical actuator assembly 31. The actuator assembly 31 may comprise an electric motor or servo, which may be operably connected to a screw, such as a roller screw, or the like. Moreover, the actuator assembly 31 may comprise another type of electro-mechanical actuator.

According to the illustrated embodiments, the lawnmower 1 comprises an input unit 33 and a control arrangement 35. The control arrangement 35 is configured to control the actuator assembly 31 to pivot the cutting unit 9 to a set angle relative to the lawnmower chassis 3 based on data from the input unit 33. Accordingly, the control arrangement 35 is configured to control the actuator assembly 31 adjust the angle between the cutting plane PC and the first plane P1 based on data from the input unit 33. According to some embodiments, the input unit 33 allows input from a user. That is, according to some embodiments, the input unit 33 allows a user to select a wanted angle between the cutting plane PC and the first plane P1, or allows a user to select between different modes or programs representing different priorities between requirements such as cutting speed, energy consumption, and cutting result. As an example, the input unit 33 may allow a user to select a mode or program prioritizing cutting speed and/or energy consumption. When such a mode or program is selected, the control arrangement 35 may control the actuator assembly 31 to pivot the cutting unit 9 to obtain a greater angle of the cutting plane PC relative to the first plane P1. As another example, the input unit 33 may allow a user to select a mode or program prioritizing cutting result. When such a mode or program is selected, the control arrangement 35 may control the actuator assembly 31 to pivot the cutting unit 9 to obtain a smaller angle of the cutting plane PC relative to the first plane P1. According to these embodiments, the input unit 33 may comprise one or more of a button, a switch, a touch sensitive screen, or the like. As an alternative, or in addition, the input unit 33 may comprise a communication unit configured to receive data from an external device, such as a computer, a computer tablet, a smartphone, or the like. Due to these features, a more user friendly lawnmower is provided capable of allowing a user to prioritize between cutting result, cutting speed, and energy consumption.

According to some embodiments of the present disclosure, the control arrangement 35 may be configured to control the actuator assembly 31 to pivot the cutting unit 9 to obtain a negative angle between the cutting plane PC and the first plane P1, seen in the forward direction fd of the lawnmower, when the lawnmower 1 is mowing in the reverse direction rd of the lawnmower, or when the lawnmower 1 is about to mow in the reverse direction rd of the lawnmower. ln this manner, a positive angle can be obtained between the cutting plane PC and the first plane P1, seen in the reverse direction rd of the lawnmower. According to these embodiments, the lawnmower may comprise an adjustment mechanism capable of adjusting the mounting position of the chassis member 3' relative to the lawnmower chassis 3 indicated in Fig. 1 so as to adjust the distance between the cutting plane PC of the cutting unit 9 and the first plane P1. Moreover, according to these embodiments, the control arrangement 35 may increase the height of the chassis member 3' relative to the first plane P1 when controlling the actuator assembly 31 to pivot the cutting unit 9 to obtain the negative angle between the cutting plane PC and the first plane P1, seen in the forward direction fd of the lawnmower during reverse mowing of the lawnmower 1. ln this manner, the cutting height can be maintained when cutting in the reverse direction rd of the lawnmower in the manner described above.

According to further embodiments, the control arrangement 35 may be configured to control the actuator assembly 31 to pivot the cutting unit 9 to a position in which the cutting plane PC is substantially parallel to the first plane P1 when the lawnmower 1 is mowing in the reverse direction rd of the lawnmower, or when the lawnmower 1 is about to mow in the reverse direction rd of the lawnmower. ln this manner, a negative angle can be avoided of the cutting plane PC relative to the first plane P1 seen in the reverse direction rd when cutting in the reverse direction rd. Moreover, in this manner, the cutting height can be maintained when cutting in the reverse direction rd of the lawnmower.

The input unit 33 may be configured to obtain data representative of a current cutting resistance, wherein the control arrangement 35 is configured to determine the set angle based on the current cutting resistance. The control arrangement 35 may be configured to determine the set angle based on the current cutting resistance such that an increased angle is obtained between the cutting plane PC and the first plane P1 with increased cutting resistance and such that a decreased angle is obtained between the cutting plane PC and the first plane P1 with decreased cutting resistance. ln this manner, the angle between thecutting plane PC and the first plane P1 can be adjusted in an automatic manner based on the length and density of the vegetation being cut and based on the travel speed of the lawn mower.

According to the illustrated embodiments, the lawnmower comprises an electric motor 17 configured to drive, i.e. rotate, the cutting unit 9 during operation of the lawnmower 1. As indicated in Fig. 5, the input unit 33 may be configured to obtain data representative of the current cutting resistance by monitoring electrical quantities of the electric motor 17. The electrical quantities of the electric motor 17 may comprise an electric current and/or an electric voltage supplied to the electric motor 17. ln this manner, data representative of the current cutting resistance can be obtained in a simple, reliable, and cost-efficient manner.

As is further explained herein, according to some embodiments, the input unit 33 may be configured to obtain data representative of a current position of the lawnmower, and wherein the control arrangement 35 is configured to determine the set angle based on the current position of the lawnmower.

Fig. 6 illustrates a lawnmower 1 according to some embodiments of the present disclosure. The lawnmower 1 illustrated in Fig. 6 comprises a chassis member 3' according to the embodiments illustrated in Fig. 5. Therefore, below, simultaneous reference is made to Fig. 5 and Fig. 6. The lawnmower 1 illustrated in Fig. 6 is illustrated as mowing a lawn comprising a first area A1 and a second area A2. The lawnmower 1 comprises an input unit 33 configured to obtain data representative of a current position of the lawnmower 1. The input unit 33 may be configured to obtain data from, or may comprise, one or more positioning units configured to estimate a current position of the robotic lawnmower 1, such as for example a space based satellite navigation system such as a Global Positioning System (GPS), The Russian GLObal NAvigation Satellite System (GLONASS), European Union Galileo positioning system, Chinese Compass navigation system, or lndian Regional Navigational Satellite System. As an alternative, or in addition, the input unit 33 may be configured to obtain data from, or may comprise, one or more positioning units utilizing a local reference source, such as a local sender and/or a wire, to estimate or verify a current position of the robotic lawnmower According to the illustrated embodiments, the first area A1 represents an area having a higher demand on lawn appearance than the second area A2. The first area A1 may for example represent an area in which a user demands a higher lawn appearance, such as an area close to a house, an area close to a walkway, an area used for sports activities, or thelike. The second area A2 may for example represent an area in which a user demands a lower lawn appearance, such as an area further away from a house, an area normally visually hidden by objects, such as a garage, shrubs, trees, garden furniture, or the like.

As explained above, according to embodiments herein, the control arrangement 35 is configured to determine the set angle based on the current position of the lawnmower 1. ln the above given example, the control arrangement 35 may determine a set angle to obtain a small positive angle between the cutting plane PC and the first plane P1 when the lawnmower is in the first area A1. When the lawnmower 1 reaches the second area A2, the control arrangement 35 determine a set angle to obtain a greater positive angle between the cutting plane PC and the first plane P1. ln this manner, the first area A1 is cut with higher precision, i.e. with a higher cutting result, than the second area A2, and the second area A2 is cut with a lower cutting resistance than the first area A1, i.e. with a reduced energy consumption. ln addition, due to the greater positive angle, the second area A2 can be cut faster. ln this manner, the lawnmower 1 allows a user to make different prioritizations between cutting result, energy consumption, and cutting speed of different areas A1, A2 of a lawn.

The control arrangement 35 may be configured to receive data representative of different areas A1, A2 of a lawn and cutting requirements thereof from an external device, such as a computer, a computer tablet, a smartphone, or the like. Such data may be sent wirelessly to the control arrangement 35 of the lawnmower 1. As an alternative, or in addition, the lawnmower 1 may comprise a touch sensitive screen, or the like, allowing input of different areas A1, A2 of a lawn and cutting requirements thereof.

The control arrangement 35 may comprise a calculation unit which may take the form of substantially any suitable type of processor circuit or microcomputer, e.g. a circuit for digital signal processing (digital signal processor, DSP), a Central Processing Unit (CPU), a processing unit, a processing circuit, a processor, an Application Specific Integrated Circuit (ASIC), a microprocessor, or other processing logic that may interpret and execute instructions. The herein utilised expression “calculation unit” may represent a processing circuitry comprising a plurality of processing circuits, such as, e.g., any, some or all of the ones mentioned above.

The control arrangement 35 may further comprise a memory unit, wherein the calculation unit may be connected to the memory unit, which may provide the calculation unit with, for example, stored program code and/or stored data which the calculation unit may need toenable it to do calculations. The calculation unit may also be adapted to store partial or final results of calculations in the memory unit. The memory unit may comprise a physical device utilised to store data or programs, i.e., sequences of instructions, on a temporary or permanent basis. According to some embodiments, the memory unit may comprise integrated circuits comprising silicon-based transistors. The memory unit may comprise e.g. a memory card, a flash memory, a USB memory, a hard disc, or another similar volatile or non-volatile storage unit for storing data such as e.g. ROM (Read-Only Memory), PROM (Programmable Read-Only Memory), EPROM (Erasable PROM), EEPROM (Electrically Erasable PROM), etc. in different embodiments.

The control arrangement 35 is connected to components of the robotic lawnmower 1 for receiving and/or sending input and output signals. These input and output signals may comprise waveforms, pulses, or other attributes which the input signal receiving devices can detect as information and which can be converted to signals processable by the control arrangement 35. These signals may then be supplied to the calculation unit. One or more output signal sending devices may be arranged to convert calculation results from the calculation unit to output signals for conveying to other parts of the robotic lawnmower's control system and/or the component or components for which the signals are intended. Each of the connections to the respective components of the robotic lawnmower 1 for receiving and sending input and output signals may take the form of one or more from among a cable, a data bus, e.g. a CAN (controller area network) bus, or some other bus configuration, or a wireless connection. ln the embodiments illustrated, the robotic lawnmower 1 comprises a control arrangement 35 but might alternatively be implemented wholly or partly in two or more control arrangements or two or more control units.

According to some embodiments of the present disclosure, the embodiments of the chassis member 3' explained with reference to Fig. 2 - Fig. 4 may be combined with embodiments of the chassis member 3' explained with reference to Fig. 5 and Fig. 6. According to such embodiments, the lawnmower 1 may comprise an actuator assembly 31 configured to pivot the cutting unit 9 relative to the lawnmower chassis 3 to a default position, such as a first position explained herein, wherein the cutting unit 9 may be configured to pivot from the default position for example based on a load exerted on the cutting unit 9 by vegetation. Moreover, according to such embodiments, the chassis member 15 may comprise one or more seats s1, s2 and a holding member 15 configured to abut against the one or more seats s1, s2, as explained with reference to Fig. 3 and Fig.Moreover, in embodiments wherein the lawnmower 1 comprises an actuator assemblyconfigured to pivot the cutting unit 9 relative to the lawnmower chassis 3 so as to change the angle between the cutting plane PC and the first plane P1, the cutting unit 9 may be pivotally arranged relative to the lawnmower chassis 3 around a second pivot point pp2, as explained with reference to Fig. 3 and Fig. lt is to be understood that the foregoing is illustrative of various example embodiments and that the invention is defined only by the appended claims. A person skilled in the art will realize that the example embodiments may be modified, and that different features of the example embodiments may be combined to create embodiments other than those described herein, 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 or more stated features, elements, steps, components, or functions but does not preclude the presence or addition of one or more other features, elements, steps, components, functions, or groups thereof.

The wording “substantially parallel to", as used herein, may encompass that the angle between the objects referred to is less than 2 degrees.

The wording “substantially corresponding to", as used herein, may encompass that the aspects, objects, distances, or measurements referred to deviates less than 7% from each other.

Claims

A lawnmower (1) comprising: - a lawnmower chassis (3), - lawnmower support members (5, 5') configured to abut against a ground surface (7) in a first plane (P1) during operation of the lawnmower (1), and - a cutting unit (9) configured to operate in a cutting plane (PC), wherein the cutting unit (9) is pivotally arranged relative to the lawnmower chassis (3) to pivot between a first position and a second position, and wherein the angle between the cutting plane (PC) and the first plane (P1) is different when the cutting unit (9) is in the second position than when the cutting unit (9) is in the first position, characterized in that the lawnmower (1) comprises an electrical actuator assembly (31) configured to pivot the cutting unit (9) relative to the lawnmower chassis (3) so as to change the angle between the cutting plane (PC) and the first plane (P1). The lawnmower (1) according to claim 1, wherein the cutting plane (PC) is substantially parallel to the first plane (P1) when the cutting unit (9) is in the first position. The lawnmower (1) according to claim 1 or 2, wherein the angle between the cutting plane (PC) and a longitudinal direction (ld) of the lawnmower (1) is different when the cutting unit (9) is in the second position than when the cutting unit (9) is in the first position. The lawnmower (1) according to any one of the preceding claims, wherein the lawnmower (1) comprises af: least one resilient element (11, 12) configured to bias the cutting unit (9) towards the first position. The lawnmower (1) according to any one of the preceding claims, wherein the lawnmower (1) comprises a_à_ least one damper (13) configured to damp movement between the cutting unit (9) and the lawnmower chassis (3). The lawnmower (1) according to any one of the preceding claims, wherein the cutting unit (9) is pivotally arranged relative to the lawnmower chassis (3) around a first pivot point (pp1), and wherein the first pivot point (pp1) is arranged in front of a centre axis (ca) of the cutting unit (9) seen in a forward direction (fd) of the lawnmower (1).The lawnmower (1) according to claim 6, wherein the first pivot point (pp1) is arranged at a distance (d1) from the centre axis (ca) within the range of 0.5 to 1.5 times a radius (r) of the cutting unit (9), or within the range of 0.8 to 1.2 times the radius (r) of the cutting unit (9). The lawnmower (1) according to claim 6 or 7, wherein the vertical distance (vd1) between the first pivot point (pp1) and cutting members (22) of the cutting unit (20) is within the range of 15% - 60%, or 25% - 45% of a radius (r) of the cutting unit (9). The lawnmower (1) according to any one of the claims 6 - 8, wherein the cutting unit (9) is pivotally arranged relative to the lawnmower chassis (3) around a second pivot point (pp2), and wherein the second pivot point (pp2) is arranged behind a centre axis (ca) of the cutting unit (9) seen in a forward direction (fd) of the lawnmower (1). The lawnmower (1) according to claim 9, wherein the second pivot point (pp2) is arranged at a distance (d2) from the centre axis (ca) within the range of 0.5 to 1.5 times a radius (r) of the cutting unit (9), or within the range of 0.8 to 1.2 times the radius (r) of the cutting unit (9). The lawnmower (1) according to any one of the preceding claims, wherein the lawnmower (1) comprises a holding member (15), wherein the cutting unit (9) is pivotally arranged relative to the lawnmower chassis (3) via the holding member (15), and wherein the holding member (15) is configured to abut against a first seat (s1) when the cutting unit (9) is in the first position, and is configured to be |ifted from the first seat (s1) when the cutting unit (9) is pivoted from the first position. The lawnmower (1) according to claim 11, wherein the holding member (15) is configured to abut against a second seat (s2) when the cutting unit (9) is in the first position. The lawnmower (1) according to claim 6 and 12, wherein the abutting contact between the holding member (15) and the second seat (s2) forms the first pivot point (pp1). The lawnmower (1) according to claim 9 and any one of the claims 11 - 13, wherein the abutting contact between the holding member (15) and the first seat (s1) forms the second pivot point (pp2). »ïåššs-.íålš ..The lawnmower (1) according to claim 14 and claim 12 or 13, wherein the cutting unit (9) is configured to be lifted from the second seat (s2) when the cutting unit (9) is pivoted around the second pivot point (pp2) from the first position. The lawnmower (1) according to any one of the preceding claims, wherein the lawnmower (1) comprises a driving unit (17) configured to drive the cutting unit (9) during operation of the lawnmower (1), and wherein the driving unit (17) is arranged to pivot with the cutting unit (9). The lawnmower (1) according to any one of the preceding claims, wherein the cutting unit (9) comprises a cutting disc (20) provided with a number of cutting members (22) arranged at a periphery (20') of the cutting disc (20). The lawnmower (1) according to claim 17, wherein the cutting members (22) are pivotally arranged to the cutting disc (20). The lawnmower (1) according to any one of the preceding claims, wherein the lawnmower (1) is a self-propelled autonomous robotic lawnmower (1). ,;I§_§_.___The lawnmower (1) according to any one of the preceding claims, wherein the lawnmower (1) comprises an input unit (33) and a control arrangement (35), and wherein the control arrangement (35) is configured to control the actuator assembly (31) to pivot the cutting unit (9) to a set angle relative to the lawnmower chassis (3) based on data from the input unit (33). lawnmower (1) according to claim wherein the input unit (33) is configured to obtain data representative of a current position of the lawnmower (1), and wherein the control arrangement (35) is configured to determine the set angle based on the current position of the lawnmower (1). lawn mower (1 ) according to wherein the in put unit (33) is configured to obtain data representative of a current cutting resistance, and wherein the control arrangement (35) is configured to determine the set angle based on the current cutting resistance. The lawnmower (1) according to claim wherein the lawnmower (1) comprises an electric motor (17) configured to drive the cutting unit (9) during operation of the lawnmower (1), and wherein the input unit (33) is configured to obtain data representative of the current cutting resistance by monitoring electrical quantities of the electric motor (17).