The present invention relates to a vacuum cleaner nozzle for a floor vacuum cleaner. Furthermore, the present invention relates to a floor vacuum cleaner comprising at least one vacuum cleaner nozzle .

A frictional resistance occurs when a vacuum cleaner nozzle of a floor vacuum cleaner, in particular a manually moved passive cleaner nozzle, is moved over a carpet by a user. Recent development gave rise to an increase in user felt motion resistance between the vacuum cleaner nozzle and the carpet, this because the mechanical interaction with the carpet has been increased in order to improve the dust pick up. On the other hand, a relative low user felt motion resistance between the vacuum cleaner nozzle and the floor or carpet is preferred in order to facilitate the work of the user. It is an object of the present invention to provide an improved vacuum cleaner nozzle for a floor vacuum cleaner that is adapted to facilitate the work for the user, eg. by reducing the user felt motion resistance between the vacuum cleaner nozzle and the floor or carpet, in particular when the mechanical interaction with the carpet is relatively high.

The object is achieved by the vacuum cleaner nozzle according to claim 1.

Preferred embodiments of the invention are subject matter of the dependent claims.

According to the present invention a vacuum cleaner nozzle for a floor vacuum cleaner comprises a nozzle unit and a joint, the nozzle unit being arranged in front of the joint,

at least one vacuum channel extending inside the nozzle unit and inside the joint,

an inlet of the vacuum channel being formed in a bottom plate of the nozzle unit,

an outlet of the vacuum channel being connectable or connected to a nozzle outlet tube of the floor vacuum cleaner, at least one wheel axle being attached at the joint, at least one wheel being attached at the wheel axle m a manner that the joint is moveable over the floor or carpet, and

at least one ball bearing that is interconnected between the wheel and the corresponding wh axle .

The ball bearing between the wheel and the corresponding wheel axle minimizes the frictional resistance between the vacuum cleaner nozzle and the floor or carpet. The arrangement of the at least one wheel at the joint on the one hand in combination with the arrangement of the nozzle unit in front of the joint on the other hand allows the nozzle unit to be easily slid over the floor. The ball bearing reduces the friction between the wheel and the wheel axle, which contributes a significant part to the total motion resistance when the vacuum cleaner nozzle is moved over the carpet or floor.

The invention is based on the observation that the frictional engagement of the wheels and the wheel axles contribute significantly to the total motion resistance of the vacuum cleaner noz- zle. This is a rather surprising result, as vacuum cleaner noz ^¬ zles typically comprise other parts that have to frictionally engage the floor or the carpet to ensure sufficient dust pick up. This contribution to the total motion resistance was believed to be the dominating contribution to the motion re- sistance. Moreover, the reduction of the friction by means of the wheels supported by the ball bearings does not negatively affect the parts engaging the floor or carpet for mechanical browsing, so that sufficient dust pick up may be provided while facilitating the manual use of the vacuum cleaner nozzle and/or the vacuum cleaner comprising said vacuum cleaner nozzle.

Preferably, the vacuum cleaner nozzle is a passive vacuum cleaner nozzle. The vacuum cleaner nozzle is adapted to be manually moved by a user. The wheels of said vacuum cleaner nozzle are non-drive wheels. In this particular embodiment, the vacuum cleaner nozzle does not comprise any drive wheels that are driven by a drive unit. In one preferred embodiment, the nozzle unit is adapted to be tilt at the joint. A tilting axis extends perpendicular to a driving direction of the floor vacuum cleaner.

In this case, the vacuum cleaner nozzle may preferably comprise at least one hinge interconnected between the nozzle unit and the joint. A hinge axis extends perpendicular to the driving direction of the floor vacuum cleaner.

For example, a tilting angle of the nozzle unit relative to the joint is between zero degrees and twenty degrees, preferably about ten degrees .

The vacuum cleaner nozzle may preferably comprise at least one bellow that is interconnected between the nozzle unit and the joint. The vacuum channel extends inside the nozzle unit, said bellow and the joint. The bellow allows for a flexible vacuum channel . In particular, the nozzle unit is tiltable relative to the joint between a forward position and a rearward position. In one preferred embodiment, the bottom plate comprises a front edge and a rear edge. The nozzle unit is preferably arranged in the forward position such that the front edge of the bottom plate touches the floor, while a rear edge of the bottom plate is spaced from said floor. In the rearward position, the nozzle unit is preferably arranged such that the rear edge of the bottom plate touches the floor, while the front edge of the bottom plate is spaced from said floor.

According to a preferred embodiment, the nozzle unit is adapted to be tilted into the forward position relative to the joint by manually pushing the floor vacuum cleaner forward. In a similar way, the nozzle unit may be tilted into the rearward position relative to the joint by manually pulling the floor vacuum cleaner rearward.

According to one preferred embodiment, the wheel axle is a sta- tionary part of the joint.

Alternatively or additionally, the wheel axle may be fixed to the joint. Even more particularly, the wheel axle may be connected to the joint in a manner that inhibits a rotation of the connected parts. Preferably, the longitudinal axis of said wheel axle corresponds with the rotation axis of the at least one wheel in the sense that the rotation axis and the longitudinal axis extend parallel to each other.

Furthermore, the present invention relates to a floor vacuum cleaner comprising a casing and a vacuum cleaner nozzle inter connected or interconnectable by an air duct. The casing includes a motor and an exhauster driven or drivable by said mo tor. The floor vacuum cleaner further includes a vacuum cleaner nozzle as described herein before.

According to one preferred embodiment, the casing and the vacuum cleaner nozzle are connected by a flexible air tube in a manner that allows the vacuum cleaner nozzle to be moved over a section of the floor by the user while the casing rests on the floor. The air tube of this embodiment provides a flexible connection between the vacuum cleaner nozzle and the casing so that the connected parts may be, at least to some extent, independently moved relative to each other.

According to another embodiment the casing and the vacuum cleaner nozzle are connected by a nozzle outlet tube in a manner that the casing and the joint of the vacuum cleaner nozzle form a rigid body or a substantially rigid body. The casing may thus be moved over the floor together with the vacuum cleaner nozzle by the user.

Additionally, the casing may preferably include at least one handle for moving the casing together with the vacuum cleaner nozzle over the floor by the user.

The present invention will be described in further detail with reference to a specific embodiment of the invention illustrated in the drawings, wherein

FIG 1 illustrates a schematic side view of a vacuum cleaner nozzle according to a preferred embodiment of the present invention, illustrates a schematic top view of the vacuum cleaner nozzle according to the preferred embodiment of the pr sent invention, and FIG 3 illustrates two diagrams of the motion resistance as a function of the suction power of the vacuum cleaner noz- zle,

FIG 4 illustrates a schematic side view of the vacuum cleaner nozzle according to the preferred embodiment of the present invention, wherein the occurring forces are represented by vectors, and

FIG 5 illustrates a schematic perspective view of a floor vacuum cleaner including the vacuum cleaner nozzle according to the preferred embodiment of the present invention. Corresponding parts are referenced by like reference numerals in all figures.

FIG 1 illustrates a schematic side view of a vacuum cleaner nozzle 10 according to a preferred embodiment of the present inven- tion. The vacuum cleaner nozzle 10 is provided for a floor vacu ^¬ um cleaner.

The vacuum cleaner nozzle 10 comprises a nozzle unit 12, a joint 14 and two wheels 16. In this example, the nozzle unit 12 is ar- ranged in front of the joint 14. The terms "front" and "rear" relate to the driving direction of the vacuum cleaner nozzle 10 during regular use thereof, that is to say when said vacuum cleaner nozzle 10 is manually pushed forwards by a user. The wheels 16 are attached at the joint 14. In this example, the wheels 16 are attached laterally at the joint 14, so that the wheels 16 are arranged behind the nozzle unit 12. In the exemplary embodiment illustrated in Fig. 1, the wheels 16 are freestanding. Alternatively, the wheels 16 may be partially arranged inside a wheel-arch formed in the joint 14 and/or in the nozzle unit 12, so that the wheels 16 are partially enclosed by the joint 14 and/or the nozzle unit 12, respectively.

Further, a nozzle outlet tube 30 to be connected to the floor vacuum cleaner is connected to the rear side of the joint 14. The nozzle outlet tube 30 acts also as a guiding rod for moving the vacuum cleaner nozzle 10.

An air channel extends from the nozzle unit 12 via the joint 14 and the nozzle outlet tube 30 to a suction blower 40 of the floor vacuum cleaner. Said suction blower 40 is not shown in FIG 1 but is illustrated in Fig. 5. The air channel extends inside of the nozzle unit 12, the bellow 28, the joint 14 and the nozzle outlet tube 30. An inlet of the air channel is formed in a bottom plate 22 of the nozzle unit 12. Preferably, the inlet of the vacuum channel extends over the nearly entire width of the bottom plate 22 of the nozzle unit 12.

Each wheel 12 is attached at a wheel axle 18 that extends later- ally from the sides of the joint 14. In this example, the wheel axles 18 extend along the rotation axes of the wheels 16, wherein each wheel axle 18 is formed as an axle.

Each wheel 16 includes a ball bearing 20. The ball bearing 20 is arranged inside the corresponding wheel 12. The ball bearing 20 is interconnected between the wheel 12 and the corresponding wheel axle 18. The ball bearing 20 reduces the frictional resistance between the wheel 12 and the corresponding wheel axle 18. Thus, the ball bearing effectively reduces the frictional resistance between the vacuum cleaner nozzle 10 and the floor.

In this example, the wheel axles 18 are stationary parts of the joint 14, while the wheels 12 are rotatable. Alternatively, the wheel axle 18 may be formed as a rotatable axle, wherein the wheel axle 18 and the corresponding wheel 12 have a common rotation axis. In the latter case, the wheel axle 18 is attached at the joint 14 by at least one further ball bearing and/or at least one sleeve bearing. Said further ball bearing and/or said sleeve bearing reduces additionally the frictional resistance between the vacuum cleaner nozzle 10 and the floor.

According to the preferred embodiment, the nozzle unit 12 is tiltable at the joint 14. The tilting axis extends horizontally and perpendicular to the driving direction of the floor vacuum cleaner. The tilting angle is between zero and twenty degrees. At least one hinge is interconnected between the nozzle unit 12 and the joint 14.

A bellow 28 is interconnected between the nozzle unit 12 and the joint 14. The bellow 28 forms the vacuum channel from the nozzle unit 12 to the joint 14. The bellow 28 allows an airtight vacuum channel, when the nozzle unit 12 is tiltable relative to the joint 14.

The nozzle unit 12 comprises a bottom plate 22. The bottom plate 22 includes a front edge 24 and a rear edge 26.

The nozzle unit 12 is tiltable relative to the joint 14 between a forward position and a rearward position. In the forward position, the front edge 24 of the bottom plate 22 touches the floor, while the rear edge 26 of the bottom plate 22 is spaced from said floor. In the rearward position, the rear edge 26 of the bottom plate 22 touches the floor, while the front edge 24 of the bottom plate 22 is spaced from said floor. When the floor vacuum cleaner is pushed forward by the user, then the nozzle unit 12 is tilted into the forward position. In contrast, when the floor vacuum cleaner is pulled rearward by the user, then the nozzle unit 12 is tilted into the rearward position. FIG 2 illustrates a schematic top view of the vacuum cleaner nozzle 10 according to the preferred embodiment of the present invention .

The vacuum cleaner nozzle 10 comprises the nozzle unit 12, the joint 14 and the two wheels 16. The nozzle unit 12 is arranged in front of the joint 14. In this example, the wheels 16 are attached laterally at the joint 14, so that the wheels 16 are ar- ranged behind the nozzle unit 12. In the preferred embodiment, the wheels 16 are free-standing. The nozzle outlet tube 30 is connected to the rear side of the joint 14, wherein said nozzle outlet tube 30 acts also as guiding rod for moving the vacuum cleaner nozzle 10.

The vacuum channel extends from the nozzle unit 12 via the joint 14, the bellow 28 and the nozzle outlet tube 30 to the suction blower of the floor vacuum cleaner. The suction blower of the floor vacuum cleaner is not shown in FIG 2. The vacuum channel extends within the nozzle unit 12, the bellow 28, the joint 14 and the nozzle outlet tube 30. The inlet of the vacuum channel is formed in the bottom plate 22 of the nozzle unit 12. A switch button 32 is arranged at the top side of the nozzle unit 12. FIG 3 illustrates two diagrams of the motion resistance MR as a function of the suction power SP of the vacuum cleaner nozzle 10.

A first diagram 34 shows the motion resistance MR as function of the suction power SP for a prior art vacuum cleaner nozzle that does not include any wheels supported by ball bearings. A second diagram 36 shows the motion resistance MR as function of the suction power SP for the vacuum cleaner nozzle 10 that includes the ball bearing 20 interconnected between the wheel 16 and the wheel axle 18. In both cases, the motion resistance MR increases with the suction power SP. However, the ball bearing 20 reduces the motion resistance MR significantly. In this example, the motion resistance MR with ball bearing 20 is about half of the motion resistance MR without ball bearing 20. Furthermore, the increase in motion resistance MR with increased suction power SP is lower compared to a prior art nozzle

The motion resistance MR is affected by several parameters, e.g. the force exerted on the vacuum cleaner nozzle by the user, the design of carpet, the suction power, the air flow pressure and/or the design of the nozzle. In order to increase the dust pick up, while decreasing the input power and/or suction power, the vacuum cleaner nozzle 10 is designed to mechanically interact with the carpet or floor more aggressively. This results in higher motion resistance MR between the nozzle and the carpet or floor, and also an increased motion resistance between the wheel 16 or wheel axle 18 on the one hand and the carpet or floor on the other hand.

FIG 4 illustrates a schematic side view of the vacuum cleaner nozzle 10 according to the preferred embodiment of the present invention, wherein the occurring forces are represented by vectors. Said forces occur, when the vacuum cleaner nozzle 10 is pushed forward by the user.

A force Fu exerted by the user extends substantially parallel to the axis of the nozzle outlet tube 30. A normal force Fn from the carpet or floor is directed upwardly and acts on the vacuum cleaner nozzle 10. A force Fsp originating from the suction power presses the vacuum cleaner nozzle 10 downwardly. A frictional force Ffw that results from the engagement of the wheel 16 with the carpet or floor and a frictional force Ffe that results from the engagement of the front edge 24 with the carpet or floor act opposite to the moving direction of the vacuum cleaner nozzle 10.

During regular use, the user exerts the force Fu on the vacuum cleaner nozzle 10 in order to move the vacuum cleaner nozzle 10 in the forward direction. The vacuum cleaner nozzle 10 is configured to direct the force Fu exerted thereon towards the wheels 16. This increases the contact and friction between the wheel axle 18 and/or wheel 16 on the one hand and the carpet or floor on the other hand, so that the motion resistance MR also increases .

A substantial part of the total friction occurs between the front edge 24 of the vacuum cleaner nozzle 10 and the carpet or floor. This is necessary in order to increase the dust pick up due to more aggressive browsing of the carpet or floor,

respectively .

The ball bearing 20 on the other hand reduces the friction between the wheel 16 or wheel axle 18 and the carpet or floor. Consequently, the total motion resistance MR is at least partially decreased by the wheels 16 that are supported by the ball bearings 20 in order to facilitate the usage of the vacuum cleaner nozzle 10. This decrease in friction does not negatively affect the frictional engagement of the front edge 24 of the vacuum cleaner 10 with the floor or the carpet, so that high dust pick up may still be provided.

FIG 5 illustrates a schematic perspective view of the floor vac- uum cleaner including the vacuum cleaner nozzle 10 according to the preferred embodiment of the present invention.

The vacuum cleaner nozzle 10 is connected to the nozzle outlet tube 30. In turn, the nozzle outlet tube 30 is connected to the suction blower 40 via a hose 38. Said hose 38 is flexible and allows that the vacuum cleaner nozzle 10 may be moved within an area and without moving the suction blower 40.

Although an illustrative embodiment of the present invention ha been described herein with reference to the accompanying drawings, it is to be understood that the present invention is not limited to that particular embodiment, and that various other changes and modifications may be affected therein by one skille in the art without departing from the scope or spirit of the in vention. All such changes and modifications are intended to be included within the scope of the invention as defined by the ap pended claims.

List of reference numerals

10 vacuum cleaner nozzle

12 nozzle unit

14 joint

16 wheel

18 wheel axle

20 ball bearing

22 bottom plate

24 front edge

26 rear edge

28 bellow

30 nozzle outlet tube

32 switch button

34 first diagram

36 second diagram

38 hose

40 suction blower MR motion resistance

SP suction power

Fu force given from the user

Fn normal force

Fsp force from the suction power Ffw frictional force of the wheel

Ffe frictional force of the edge