TECHNICAL FIELD

The present invention relates to a side brush for a robotic cleaner, such as a robotic vacuum cleaner. The present invention further relates to a robotic cleaner, such as a robotic vacuum cleaner.

BACKGROUND

A robotic vacuum cleaner forms a self-propelling unit provided with a drive arrangement comprising a control system configured to control a movement of the robotic vacuum cleaner along a surface to be cleaned. The control system may comprise one or more sensors providing input to assist in controlling the movement of the robotic vacuum cleaner. A suction producing unit of the robotic vacuum cleaner is arranged in fluid communication with an opening of a nozzle inlet facing the surface to be cleaned. Dust and debris sucked or otherwise propelled into the opening is directed into a debris receptacle of the robotic vacuum cleaner. The debris receptacle is emptied, or replaced, when filled with dust and debris to a certain degree.

Robotic cleaners, such as robotic vacuum cleaners, configured to travel along a surface to be cleaned may be provided with so called side brushes. A side brush is rotatable about a substantially vertical axis and comprises bristles extending outwardly from the rotation axis. The side brush may sweep dust and debris from beside, and/or a side portion of, the robotic cleaner to underneath the robotic cleaner for further transportation into a debris receptacle inside the robotic cleaner. The side brush may be arranged to reach into narrow corners and crevices where an elongated brush roll underneath the robotic cleaner and/or the suction produced in the robotic cleaner does not reach.

The side brush comprises a number of bristles. As the side brush rotates and the robotic cleaner travels towards an obstacle in the form of e.g. a carpet edge or a cable, one or more of the bristles may project underneath the obstacle. If the robotic cleaner continues to travel towards the obstacle, the one or more bristles may be caught underneath the obstacle. The one or more bristles may fold and the side brush may entangle with the obstacle. In worst case, the robotic cleaner may be prevented from continuing travelling along the surface to be cleaned, or the robotic cleaner may drag the obstacle with it along the floor resulting in potential furniture damage, as the robotic cleaner may be difficult to control. It is known to provide the side brush with few bristles and/or long bristles to reduce this problem. However, both these solutions provide a poor cleaning result with the side brush. A further way of reducing this problem is to provide the bristles in bunches, each bunch being connected to a central portion of the side brush by means of tubular portion, which bundles the bristles of each bunch. That is, the bristles do not extend freely directly from the central portion, but extend instead freely from the tubular portion at a distance from the central portion. Also this solution provides a poor cleaning result since the bristles will be bundled in distinct bunches thinly distributed around the side brush. SUMMARY

It is an object of the present invention to provide an alternative side brush, which does not entangle easily underneath an obstacle as a related robotic cleaner travels towards the obstacle. According to an aspect of the invention, the object is achieved by a side brush for a robotic cleaner, the side brush being rotatable about a rotation axis in a rotational direction and comprising a brush body and numerous linear bristles including a first bristle having a base end at the brush body and an opposite distal end. The numerous bristles extend freely from the brush body to their respective distal ends. The rotation axis extends centrally through the brush body and an imaginary line extends perpendicularly to the rotation axis. The first bristle is arranged with its base end at a distance from the rotation axis on the imaginary line extending in a bristle direction outwardly from the brush body. Seen in a top view, along the rotation axis, the bristle direction extends at a first angle to the imaginary line with the distal end pointing rearwardly in relation to the rotational direction. Seen in a side view, along the imaginary line, the bristle direction extends at a second acute angle to the rotation axis pointing away from the brush body.

Due to the first bristle of the side brush being directed both in a rearward direction in relation to the rotational direction of the side brush and a downward direction during use of the side brush, if the distal end of the first bristle is pushed underneath an obstacle such as a carpet or a cable, the base end of the first bristle closest to the brush body will be angled such that upon further rotation of the side brush, the first bristle will be biased upwardly over the obstacle. Accordingly, the first bristle and will not entangle with the obstacle. As a result, the above mentioned object is achieved. Moreover, in a side brush having all its numerous bristles arranged in a same manner as the first bristle, the numerous bristles may be arranged more densely than in a side brush with bristles extending radially from the brush body, while still preventing the side brush from entangling with an obstacle. Herein, a linear bristle refers to a bristle which is straight in an unloaded state, i.e. when the bristle of the brush does not abut against any surface to be cleaned. When mounted in a robotic cleaner, the bristle will abut against a surface to be cleaned. Suitably the bristle will be curved to a certain extent when it abuts against the surface to be cleaned. Thus, the bristle will be biased with a force towards the surface to be cleaned. The imaginary line extending perpendicularly to the rotation axis may entail that the imaginary line extends substantially horizontally in use of the side brush in a robotic cleaner. The brush body forms a central portion of the side brush. The brush body may comprise an interface configured for connection to a rotation axle of a relevant robotic cleaner. The side brush may be removably secured to the robotic cleaner.

The bristles may be arranged in discrete bunches of bristles. In such embodiments the maximum distance between the bristles of the side brush may be between one bristle of a first bunches of bristles and a further bristle of an adjacent bunch of bristles. Alternatively, the bristles may be arranged in one or more continuous lines in a circular direction around the brush body. In such embodiments all bristles may even be arranged one bristle abutting against at least one further bristle all around the brush body.

According to embodiments, the numerous bristles may be similarly arranged around the brush body as the first bristle. In this manner the numerous bristles of the side brush may extend rearwardly and downwardly to form, in an unloaded state, a substantially frustoconical brim of bristles.

According to a further aspect of the present invention, the above-mentioned object is achieved by a robotic cleaner. The robotic cleaner comprises a housing, a drive arrangement being configured to drive the robotic cleaner along a surface to be cleaned, a debris receptacle arranged inside the housing, a nozzle inlet in the housing facing the surface to be cleaned, and a side brush comprising bristles configured to abut against the surface to be cleaned. The side brush is rotatable about a substantially vertical rotation axis. The side brush is a side brush according to any aspect and/or embodiment discussed herein.

The robotic cleaner may be a self-propelling unit. The robotic cleaner may be a robotic vacuum cleaner, which comprises a suction producing unit. The side brush may sweep dust and debris from beside, and/or a side portion of, the robotic cleaner to underneath the robotic cleaner towards, or into, the nozzle inlet for further transportation into the debris receptacle inside the robotic cleaner. The side brush may be arranged to reach into narrow corners and crevices where an elongated brush roll underneath the robotic cleaner and/or suction produced in the robotic cleaner does not reach.

According to embodiments, the side brush may be arranged at a peripheral portion of the housing, which peripheral portion faces the surface to be cleaned. In this manner the side brush may reach laterally at least to an outer periphery of the housing to propel dust and debris towards the nozzle inlet in the housing.

According to embodiments, the housing may comprise a bottom surface in, or at, the peripheral portion. The bottom surface may be provided with a recess. The brush body of the side brush may be arranged in the recess at a depth such that the base end of the first bristle is positioned within the recess and during use of the robotic cleaner the base end is arranged above the bottom surface. In this manner, if the first bristle should slide underneath an obstacle such as a carpet or a cable, the obstacle may follow along the first bristle only to the bottom surface of the housing, but may not reach the base end of the first bristle. Thus, the obstacle is prevented from entangling with the bristles of the side brush. Naturally, the side brush may be arranged in the recess such that the base ends of all the numerous bristles of the side brush are positioned within the recess. According to embodiments, the numerous bristles may have a curved shape during use of the robotic cleaner. The curved shape may be due to the initially straight bristles abutting against the surface to be cleaned.

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:

Figs. 1 a - 1 c illustrate schematically various views of a side brush according to

embodiments,

Figs. 2a - 2c illustrate schematically a brush body and a first bristle of the side brush illustrated in Figs. 1 a - 1 c,

Figs. 3a - 3c illustrate various views of the side brush of Figs. 1 a - 1 c in a loaded state, Figs. 4a and 4b illustrate a top view and a bottom view of a robotic cleaner according to embodiments, Fig. 5 illustrates a bottom view of the robotic cleaner of Figs. 4a and 4b with a side brush removed, and

Fig. 6 illustrates a cross section of the robotic cleaner Figs. 4a and 4b. 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. Figs. 1 a - 1 c illustrate schematically various views of a side brush 2 according to

embodiments. The side brush 2 is configured for use with a robotic cleaner, such as a robotic vacuum cleaner. The side brush 2 is rotatable about a rotation axis 4 in a rotational direction 6, indicated with an arrow. The side brush 2 comprises a brush body 8 and numerous linear bristles 10 including a first bristle 12. The rotation axis 4 extends centrally through the brush body 8. Each of the numerous bristles 10 has a base end at the brush body 8 and a distal end. The numerous bristles 10 extend freely from the brush body 8 to their respective distal ends, corresponding to the distal end of the first bristle 12. In Figs. 1 a - 1 c the side brush 2 is illustrated in an unloaded state, i.e. when side brush 2 is handled as a separate part and it is not mounted in a relevant robotic cleaner

Figs. 2a - 2c illustrate schematically the brush body 8 and the first bristle 12 of the side brush 2 illustrated in Figs. 1 a - 1 c. The remaining bristles have been omitted for the sake of clarity. The first bristle 12 has a base end 14 at the brush body 8 and an opposite distal end 16. An imaginary line 18 extends perpendicularly to the rotation axis 4, see Figs. 2a, 2b. The first bristle 12 is arranged with its base end 14 at a distance from the rotation axis 4 on the imaginary line 18, see Fig. 2b. The first bristle 12 extends in a bristle direction 20 outwardly from the brush body 8. Seen in the top view of Fig. 2b, i.e. along the rotation axis 4, the bristle direction 20 extends at a first angle a to the imaginary line 18 with the distal end 16 pointing rearwardly in relation to the rotational direction 6. Seen in the side view of Fig. 2c, along the imaginary line 18, the bristle direction 20 extends at a second acute angle β to the rotation axis 4. Thus, the first bristle 12 points away from the brush body 8. Accordingly, seen in the rotational direction 6, the base end 14 travels ahead of the distal end 16.

Returning to Figs. 1 a - 1 c, each of the numerous bristles 10 are similarly arrange around the brush body 8 as the first bristle 12. Depending on the attachment arrangement of the bristles to the brush body 8, the first angle a and second acute angle β of each bristle may vary by a few degrees. However, all the numerous bristles of the side brush 2 extend rearwardly and downwardly from the brush body, such that seen in the rotational direction 6, the respective base ends of the numerous bristles 10 travel ahead of the respective distal ends of the numerous bristles 10 as the side brush 2 rotates in the rotational direction 6. In these embodiments the first angle a is approximately 50 degrees. According to alternative embodiments, the first angle a may be within a range of 30 - 90 degrees to the imaginary line 18. According to preferred embodiments, the first angle a may be within a range of 45 - 90 degrees. In these embodiments the second acute angle β is approximately 40 degrees. According to alternative embodiments, the second acute angle β may be within a range of 1 - 85 degrees to the rotation axis 4. According to preferred embodiments, the second acute angle β may be within a range of 30 - 75 degrees. Each of the numerous bristles 10 may have a diameter within a range of 0,05 - 0,3 mm, preferably within a range of 0,1 - 0,2 mm.

Each of the numerous bristles 10 may have a length within a range of 15 - 200 mm, preferably within a range of 40 - 70 mm.

The numerous bristles 10 may comprise bristles made from natural fibres, e.g. horsehair, and/or bristles made from synthetic material, e.g. Polybutylene terephthalate (PBT), or nylon.

A diameter of the side brush 2 may be within a range of 40 - 200 mm, preferably within a range of 80 - 160 mm. The diameter is that of an unloaded side brush 2, as illustrated in Figs. 1 a - 1 c.

According to embodiments, the side brush 2 may have a mean bristle density of at least 3 bristles/degree with a maximum distance between at least two of the numerous bristles 10 of 30 degrees. In this manner a dense side brush 2 may be provided, which renders a thorough cleaning result. Due to the above discussed first angle a and second acute angle β, even with a side brush 2 having such densely arranged bristles, the entangling with objects may be avoided. In these embodiments the numerous bristles 10 are arranged in eight bunches 24 of bristles around the bristle body 8. According to alternative embodiments, the numerous bristles 10 may be arranged in at least eight bunches 24 of bristles around the brush body 8. In a side brush having the bristles arranged in bunches of bristles, locally the bristle density may be considerably higher than the above-discussed 3 bristles/degree. However, the mean bristle density over the entire circumference suitably may be at least 3 bristles/degree.

According to embodiments, each of the at least eight bunches 24 of bristles may comprise at least 150 bristles. In this manner the above mentioned mean bristle density may be achieved. According to embodiments, the brush body 8 may be substantially circular with a diameter within a range of 15 - 70 mm, preferably within a range of 20 - 50 mm.

Figs. 3a - 3c illustrate various views of the side brush 2 of Figs. 1 a - 1 c in a loaded state, i.e. as when the side brush 2 is mounted in a robotic cleaner and abuts against a surface 22 to be cleaned. The numerous bristles 10 adapt a curved shape when at least some of them abut against the surface 22 to be cleaned. Thus, the numerous bristles 10 will be biased with a force towards the surface 22 to be cleaned. The biasing force depends inter alia on the height the brush body 8 in a housing of a relevant robotic cleaner above the surface 22 to be cleaned, the length of the numerous bristles 10, and the stiffness of the numerous bristles 10.

Figs. 4a and 4b illustrate a top view and a bottom view of a robotic cleaner 30 according to embodiments. The robotic cleaner 30 comprises a housing 32, a drive arrangement 34 being configured to drive the robotic cleaner 30 along the surface to be cleaned, a debris receptacle 36 arranged inside the housing 32, a nozzle inlet 38 in the housing 32 facing the surface to be cleaned, and a side brush 2 according to any aspect and/or embodiment discussed herein.

The robotic cleaner 30 is a self-propelling unit. The drive arrangement 34 comprises four wheels, of which at least one wheel is directly or indirectly driven by an electric drive motor arranged inside the housing 32. The drive arrangement 34 further comprises a control system configured to control the electric drive motor to move the robotic cleaner 30 about the surface to be cleaned. The control system may comprise one or more sensors to provide input assisting in controlling the movement of the robotic cleaner 30. The at least one sensor may be of one or more different kinds, such as e.g. an infrared sensor, a laser sensor, an ultrasonic sensor, or a contact sensor. The nozzle inlet 38 communicates with the debris receptacle 36 such that dust and debris may be transported from the nozzle inlet 38 into the debris receptacle 36. A rotating brush roll 40 arranged inside the housing at the nozzle inlet 38, and having a rotation axis extending substantially in parallel with the surface to be cleaned, may assist in propelling dust and debris into the debris receptacle 36. The side brush 2 is configured to transport dust and debris towards the nozzle inlet 38. The side brush 2 and the brush roll 40 may be driven by one or more electric brush motors. Besides controlling the drive motor, the control system may also control the one or more brush motors. The debris receptacle 36 may be removable to be emptied. The debris receptacle 36 may comprise a disposable bag, inside which dust and debris are collected.

The robotic cleaner 30 is a robotic vacuum cleaner, which comprises a suction producing unit. The suction producing unit may comprise a fan driven by an electric fan motor. The control system may also control the fan motor. The nozzle inlet 38 is arranged in fluid communication with the debris receptacle via a debris conduit system. The suction producing unit is arranged in fluid communication with the nozzle inlet 38 via the debris conduit system and optionally also via the debris receptacle 36, i.e. the vacuum producing unit in some embodiments may create a suction from the nozzle inlet 38 via the debris conduit system to the debris receptacle 36. The robotic cleaner 30 comprises one or more rechargeable batteries configured to power the drive arrangement 34 including the control system and the various electric motors.

The side brush 2 is arranged at a peripheral portion 39 of the housing 32, which peripheral portion 39 faces the surface to be cleaned. In these embodiments the numerous bristles 10 extend beyond the housing 32, seen in the top view of Fig. 4a. In alternative embodiments, the numerous bristles may not reach beyond the housing, seen in a top view, but may extend only to an edge of the housing. Fig. 5 illustrates a bottom view of the robotic cleaner 30 of Figs. 4a and 4b with the side brush removed. A drive shaft 42 for the side brush protrudes from the housing 32.

Fig. 6 illustrates a cross section of the robotic cleaner 30 along line VI - VI in Fig. 4a. The first bristle 12 and a further bristle of the side brush 2 are schematically illustrated, abutting against a surface 22 to be cleaned. The remaining bristles have been omitted for the sake of clarity. Due to at least some of the bristles abutting against the surface 22 to be cleaned, the bristles have a curved shape during use of the robotic cleaner 30, when it travels along the surface 22 to be cleaned.

The side brush 2 is rotatable about its substantially vertically extending rotation axis 4 by an electric brush motor 44. The brush motor 44 is connected to a transmission 46 comprising the drive shaft 42. The side brush 2 is connected to the drive shaft 42.

Suitably, the brush body 8 of the side brush 2 comprises an interface configured for connection to the drive shaft 42. The interface may e.g. comprise an opening for receiving an end of the drive shaft 42. If the drive shaft 42 is made from a magnetic material, a magnet member 48 may be arranged in the brush body 8 to ensure that the side brush 2 is removably secured to the drive shaft 42 and the robotic cleaner 30. Thus, the side brush 2 may be easily removed for cleaning or to be replaced. According to embodiments, the housing 32 comprises a bottom surface 50 in, or at, the peripheral portion 39. The bottom surface 50 is provided with a recess 52. The drive shaft 42 extends into the recess 52, see also Fig. 5. The brush body 8 of the side brush 2 is arranged in the recess 52, attached to the drive shaft 42, at a depth such that the base end 14 of the first bristle 12 is positioned within the recess 52.

During use of the robotic cleaner 30, the base end 14 is arranged above the bottom surface 50, i.e. higher above the surface 22 to be cleaned than the bottom surface 50. Accordingly, if the first bristle 12 should slide underneath an obstacle, such as a carpet or a cable, the obstacle may follow along the first bristle 12 upwardly only to the bottom surface 50, but may not reach the base end 14 of the first bristle 12. At the bottom surface 50 the obstacle slips off the first bristle 12, as the side brush 2 rotates. Accordingly, the obstacle will not entangle with the side brush 2. Also the base ends of all the non-shown bristles of the side brush 8 are positioned within the recess 52. Embodiments of the robotic cleaner 30 comprising the above discussed recess 52 in the bottom surface 50 may prevent obstacles from entangling with side brushes of different types than discussed above. For instance, also in a robotic cleaner comprising a side brush with bristles extending radially from the brush body, and having the base ends of the bristles arranged within the recess 52, an obstacle may slip off the side brush as the obstacle reaches the bottom surface 50, as the side brush rotates.

Thus, according to a further aspect there is provided a robotic cleaner 30 comprising a housing 32, a drive arrangement 34 being configured to drive the robotic cleaner 30 along a surface 22 to be cleaned, a debris receptacle 36 arranged inside the housing 32, a nozzle inlet 38 in the housing 32 and facing the surface 22 to be cleaned, and a side brush 2. The side brush 2 comprises a brush body 8, to which numerous bristles 10 including a first bristle 12 are attached. At least some of the numerous bristles 10 are configured to abut against the surface 22 to be cleaned. The side brush 2 is rotatable about a substantially vertical rotation axis 4. The housing 32 comprises a bottom surface 50. The bottom surface 50 is provided with a recess 52. The brush body 8 of the side brush 2 is arranged in the recess 52 at a depth such that a base end 14 of the first bristle 12 is positioned within the recess 52 and during use of the robotic cleaner 30 the base end 14 is arranged above the bottom surface 50.

The description above, in particular relating to Figs. 4a, 4b, 5, and 6, also applies to this further aspect. Thus, the same description and the same reference numbers apply to this further aspect.

This invention should not be construed as limited to the embodiments set forth herein. A person skilled in the art will realize that different features of the embodiments disclosed herein 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.

Although the invention has been described with reference to example embodiments, many different alterations, modifications and the like will become apparent for those skilled in the art. For instance may the drive arrangement alternatively comprise three wheels or more than four wheels. A robotic vacuum cleaner may rely on suction only to collect dust and debris, i.e. in some embodiments the elongated brush roll may be omitted. Therefore, it is to be understood that the foregoing is illustrative of various example embodiments and that the invention is defined only 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.