Electric utility brush with a dynamic brush head

An electric utility brush with a dynamic brush head which has a rotatable head which is capable of undergoing rotation about two separate axes in order to effect multiple modes of brushing.

This application is a 371 of International Application No. PCT/EP2018/051764, filed Jan. 25, 2018, which claims the priority of IE Application No. S2017/0028, filed Jan. 27, 2017 which is incorporated herein in its entirety.

FIELD OF THE INVENTION

The present invention is concerned with an electric utility brush with a dynamic brush head, and in particular a handheld electric utility brush such as an electric toothbrush or the like, which has a rotatable head which is capable of undergoing rotation about two separate axes in order to effect multiple modes of brushing.

BACKGROUND OF THE INVENTION

Electric brushes for various applications, for example electric toothbrushes, polishing brushes, cleaning brushes, etc. are well known and take many forms, generally incorporating a head with an array of bristles, and drive means, usually in the form of an electric motor or the like, which are adapted to impart at least one driving motion to the head.

For an electric toothbrush one of the most common driving motions is rotational. In some cases a number of driving modes may be available, for example allowing the brush head to be rotationally driven about one axis as one driving mode, and alternatively about a second axis as a second driving mode. This may be beneficial for certain applications, for example in the case of an electric toothbrush allowing the axis of rotation of the brush head to be located in two or more different orientations to provide the most efficient brushing action for the particular group of teeth being brushed.

It may however be desirable, when brushing teeth in certain areas of the mouth, for example adjacent the cheek, to avoid such rotational motion of the brush head as a portion of the brush head will be pressed against the soft tissue of the cheek and the bristles of the rotating head will thus rub against the cheek and may cause discomfort or irritation.

Due to the small size of hand held toothbrushes, in particular the brush head itself, significant design and manufacturing limitations are encountered when attempting to produce the various drive components to enable the above described dual axis rotation, which requires said complex drive components to be located on the interior of the head and thus in extremely limited space. In addition, the brush head requires an array of bristles projecting from the outer surface, and said bristles must be sufficiently mechanically secured to the head to be robust and provide the necessary working life expected of such a product. This is a further complication in terms of having available space within the head to anchor the bristles, and from a manufacturing perspective when working with such diminutive parts.

It is therefore an object of the present invention to address the above-mentioned issues.

SUMMARY OF THE INVENTION

An electric utility brush comprising an inner drive shaft and a concentric outer drive shaft; a rotatable head comprising a first part fixed to an end of the outer drive shaft, and a second part rotatably mounted to the first part in driving engagement with the inner drive shaft.

Preferably, the brush head is spherical, the first and second parts being substantially hemispherical.

Preferably, the first part is larger in size than the second part.

Preferably, the second part of the head comprises an axle projecting from an end face and the first part of the head comprises a complementary socket in which the axle is seated.

Preferably, the brush head comprises a bearing disposed between the axle and the socket.

Preferably, the bearing comprises a bushing retained in the socket.

Preferably, the bushing comprising a sleeve within which the axle is located and a flange extending radially outward from an end of the sleeve and located between the first and second parts of the head.

Preferably, the flange defines at least a pair of parallel sides.

Preferably, the utility brush comprises a set of meshing gears provided between the inner drive shaft and the second part of the head.

Preferably, the set of meshing gears comprise driving gear teeth formed integrally with an end of the inner drive shaft and complementary driven gear teeth formed integrally with an end face of the second part of the head.

Preferably, the brush head comprises an array of bristles projecting from an outer surface

Preferably, the utility brush comprises a sleeve at least partially surrounding the outer drive shaft.

Preferably, the utility brush comprises an indexing mechanism operable to locate the outer drive shaft at a set angular orientation when the inner drive shaft is being driven independently of the outer drive shaft.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring now to the accompanying drawing, there is illustrated an electric utility brush, generally indicated as10, which has particular application in small hand-held devices such as an electric toothbrush (not shown) or the like.

The utility brush10comprises a brush head12which in the embodiment illustrated is substantially spherical in form, and comprising a first part14which is substantially hemispherical and a second part16which is also substantially hemispherical and is rotatably mounted to the first part14. While both the first part14and the second part16are substantially hemispherical in shape, in the preferred embodiment illustrated the first part14is larger than the second part16, which provides a number of design and manufacturing advantages as described in detail hereinafter.

The utility brush10further comprises a solid inner drive shaft18and a concentrically located hollow outer drive shaft20which surrounds the inner drive shaft18, both drive shafts18,20being in operative engagement with the brush head12in order to effect the rotation thereof, again as will be described in detail hereinafter. The utility brush10may additionally comprise an outer protective sleeve22surrounding the outer drive shaft20, and which remains fixed during use while the inner and outer drive shafts18,20may be rotated therein. In use, the inner and outer drive shafts18,20, along with the sleeve22will form a neck or stem of an electric toothbrush, a body or handle (not shown) being provided at an end thereof opposed to the head12in order to allow the user to manually grasp the utility brush10, the body or handle (not shown) also providing a location at which an electric motor, battery, and control circuitry may be housed. No further explanation of these components is provided hereinafter, and it will be appreciated that any other suitable functional equivalents may be provided in place thereof.

The first part14of the brush head12includes a cylindrical socket24formed therein, while the second part16of the brush head12comprises a short axle26projecting outwardly therefrom and which, with the first and second parts14,16secured to one another, is located within the socket24. It will be appreciated that the second part16is shown slightly separated from the first part14inFIG.1to allow a clearer understanding of the configuration and operation of the utility brush10.

The brush head12additionally comprises a bearing in the form of a bushing28provided between the socket24and the axle26, the bushing having a cylindrical sleeve30in which the axle26is retained for rotation and a radially extending flange32which in use is positioned between the opposed faces of the first and second parts14,16of the brush head12. In the preferred embodiment illustrated, the cylindrical wall of the socket24is threaded and the outer surface of the sleeve30is provided with a corresponding thread in order to allow the second part16, with the bushing28located about the axle26, to be threaded into the first part14in order to secure the first and second parts14,16together as the spherical brush head12. The flange32is therefore preferably of hexagonal shape such as to effectively define a nut or bolt head which can be engaged by a thin spanner to turn the bushing28in order to thread the bushing28into the threaded socket. It will therefore be understood that the flange32must have at least a pair of parallel sides or edges, and is most preferably hexagonal in shape.

The axle26is provided with a threaded end34onto which a nut36is threaded once the axle26has been inserted into the bushing28and before the bushing28is threaded into the socket24. The nut36is tightened against a shoulder38formed on the axle26a small distance outboard of the end of the sleeve30, the nut36overlapping the end of the sleeve30in order to prevent the axle26from being withdrawn from the sleeve30while still allowing the second part16to rotate freely within the bushing28. In this way, the second part16can be rotated in the bushing28and relative to the first part14about a longitudinal axis of the axle26.

Turning then to the connection between the brush head12and the drive shafts18,20, the first part14of the brush head12is fixed to or formed integrally with an end of the outer drive shaft20thereby allowing the entire brush head12to be rotated about a longitudinal axis of the drive shafts18,20by rotating the two drive shafts18,20in unison. This will ensure that the second part16remains fixed relative to the first part14as the entire brush head12undergoes rotation on this axis.

The utility brush10also comprises a gear set in the form of driving gears40provided on or formed integrally with an end of the inner drive shaft18, and a complimentary set of driven gears provided on or formed integrally with the second part16of the brush head12. The driving gears40and driven gears42mesh with one another when the second part16is secured to the first part14of the brush head12, allowing drive to be transferred through 90 degrees from the inner drive shaft18to the second part16, in order to effect rotation of the second part16relative to the first part14when the inner drive shaft18is driven independently of the outer drive shaft20.

Thus in use the utility brush10is capable of imparting first and second independent brushing motions to the brush head12, a first brushing motion in which the entire brush head12is rotated about a longitudinal axis of the drive shafts18,20through synchronous rotation of the drive shafts18,20, and a second independent brushing motion in which the outer drive shaft20is immobilised and only the inner drive shaft18is rotated therein, thereby effecting rotation of the second part16of the brush head12about a longitudinal axis of the axle26, which is therefore perpendicular to the first brushing motion. This motion is particularly suited to the electric toothbrush application of the utility brush10, as if the stationary first part of the brush head12may be placed against the inside of the cheek while the rotating second part16effects cleaning of the surface of the teeth facing the cheek, thus avoiding any irritation of the soft tissue of the cheek which might otherwise occur if the entire brush head12were rotated as this would result in abrasion of the cheek which would be particularly pronounced where the outer surface of the brush head12is covered in an array of bristles as is conventionally the case with a toothbrush head.

By fixing the first part14of the head12to the outer drive shaft20it is possible to increase the size of the first part14relative to the second part16, such that the first part14is greater in size than a hemisphere and the second part is thus correspondingly reduced in size to be less than a hemisphere. This increase in the size of the first part14provided increased space on the interior of the head12to both accommodate the drive components and to secure tufts of bristles to the head12.

The utility brush10may therefore be provided with suitable controls (not shown) which allow the first or second brushing motion to be selected by the user, or to be selected automatically depending on the orientation of the utility brush10. The utility brush10may additionally or alternatively comprise an indexing mechanism (not shown) which may be operable to locate the outer drive shaft20at a set angular orientation when the inner drive shaft18is to be driven independently of the outer drive shaft20in order to effect independent rotation of the second part16of the brush head12.