The present invention relates generally to the field of garbage shredders, more particularly to garbage shredders for use in household environments and still more particularly to garbage shredders for use in household environments, which are particularly suited for comminuting carton or plastic packagings.

BACKGROUND OF THE INVENTION

A number of waste shredding devices and apparatuses are commercially available of which a number of these are specifically designed for use in industry or other places where large amounts of waste material have to be shredded for instance for recycling. Also, a number of waste shredding devices designed for use at home are available and one such device is described in US 8,393,562 B1 that describes a plastic shredder.

The device described in US 8,393,562 B1 comprises an interior channel extending between a top and a bottom portion of the device. An upper roller and a lower roller are positioned in the channel and extend across the channel. An intermediate gap is formed between the upper and lower roller. The rollers are provided with radially extending teeth configured such that the teeth of the upper roller mesh with the teeth of the lower roller. When the rollers rotate, material to be shredded are drawn through the gap formed between the rollers. The shredded waste material is collected in an ordinary garbage bin upon which the device can be placed.

Due to the relatively narrow gap formed between the rollers (and between the meshing teeth of the rollers) there is a risk for waste material being clogged between the rollers and thereby preventing the rollers to rotate causing an annoying halt of the device. Also, the cutting assembly of this device is somewhat cumbersome for a user to remove from the device, for instance in order to clean the channel, rollers and teeth.

On this background, there is a need to provide a household waste shredder that is easy to maintain and clean if it for instance becomes clocked by waste material.

OBJECTS OF THE INVENTION

On the above background, it is an object of the present invention to provide a household waste shredder configured to handle ordinary household waste.

l It is a further object of the present invention to provide a household waste shredder of limited dimensions and weight that can easily be placed into a normal kitchen or utility room environment or alternatively be installed in a kitchen table or cupboard or the like.

It is a further object of the invention to provide a household waste shredder that can easily be cleaned and maintained.

It is a further object of the present invention to provide a household waste shredder that is safe to operate.

It is a further object of the invention to provide a household waste shredder with limited noise emission. SUMMARY OF THE INVENTION

The above and further objects and advantages are according to the present invention provided by a mobile household waste shredder for carton/cardboard and plastic packaging refuse, the waste shredder comprising:

- an outer container or housing defined by a longitudinal axis L and at a first longitudinal end provided with an openable/closeable lid configured such that household waste can be introduced into an interior portion of the outer container, when the lid is in an open state;

- a waste reception region provided at said first longitudinal end of the outer container;

- a shredded waste reception region provided in the outer container adjacent a waste bin;

- a removable waste bin provided adjacent said shredded waste reception region and configured to receive and accommodate shredded waste, where the waste bin is provided in the outer container substantially at a second longitudinal end of the outer container opposite said lid and in communication with said shredded waste reception region;

- a cutting device configured to receive waste to be shredded from the waste reception region in an waste inlet portion of the cutting device and to provide shredded waste to the shredded waste reception region from a shredded waste outlet portion, where the cutting device comprises an inner cylindrical container subdivided in sections by a number of cutter discs, one cutter disc being provided between each adjacent section, the cutter discs being cylindrical with an individual diameter di substantially equal to the inner diameter of the inner cylindrical container at the respective position of the inner cylindrical container, at which position the respective cutter disc is located, where the cutter discs are mounted for co-rotation with a longitudinal drive shaft extending longitudinally through the inner cylindrical container, where the drive shaft is connected to a motor or similar means configured to rotate the drive shaft at a predetermined rotational speed;

- where said shredded waste outlet portion is in communication with said shredded waste reception region.

Although more than one cutter discs are preferably used in the household waste shredder according to the invention, this does not rule out the possibility to use only a single cutter disc, if this is regarded as sufficient. In an embodiment of the invention, a contact region is formed between an outer circumferential edge portion of the respective cutter discs and the corresponding inner circumferential surface of the inner cylindrical container, where the contact region is provided with contact means configured to ensure that contact is maintained between the outer circumferential edge portion of the respective cutter discs and the corresponding inner circumferential surface of the inner cylindrical container, when the cutter discs are rotating about the longitudinal axis.

In an embodiment of the invention, the contact means comprises a roller bearing extending between the outer circumferential edge portion of the respective cutter discs and the corresponding inner circumferential surface of the inner cylindrical container, whereby a smooth and substantially frictionless contact between the outer circumferential edge portion of the respective cutter discs and the corresponding inner circumferential surface of the inner cylindrical container is obtained.

In an embodiment of the invention, the cutter discs comprise cutter blades that extend radially over more than 50% of the diameter of the respective disc, preferably more than 75% of the diameter of the respective disc and still more preferably over more than 90% of the diameter of the respective disc, thereby facilitating maximum flow of shredded waste material through the cutter discs.

In an embodiment of the invention, the cutter discs are provided with cutter blades extending radially from a hub portion of the respective disc towards its periphery, and wherein through going passages are provided between adjacent cutter blades such that waste can pass through the cutter disc, where the respective cutter blades are provided with a leading cutting edge and where the cutter blades are configured such that they - when rotated about the longitudinal axis L - generates an air flow through said passages that will urge the waste through the cutter discs.

In an embodiment of the invention, an air passage is established in the interior space defined between the outer container and the inner cylindrical container, which air passage provides air communication between the shredded waste reception region and the waste reception region.

In an embodiment of the invention, a first cutter disc is provided closest to the waste reception region configured to chop the waste coarsely and one or more further cutter discs are configured to chop the waste more and more finely, the closer the specific cutter disk is located to the shredded waste outlet portion of the cutting device.

In an embodiment of the invention, the inner cylindrical container is provided with a longitudinally extending slit extending from one longitudinal end of the inner cylindrical container to the opposite longitudinal end hereof, whereby the diameter of the inner cylindrical container can be increased, thereby facilitating removal of the inner cylindrical container from the cutting device and/or outer container.

In an embodiment of the invention, one or more sensors are provided in the lid and/or an upper edge portion of the outer container, which sensors provide signals to a control system incorporated in the waste shredder, where the control system is configured to only allow the drive motor to be started, when the lid is in its closed position on the outer container.

In an embodiment of the invention, one or more sensors are provided in or adjacent the shredded waste reception region, which sensors provide signals to a control system incorporated in the waste shredder, where the control system is configured to stop the drive motor, when the waste bin is removed from the outer container.

In an embodiment of the invention, the household waste shredder comprises a control system and a user interface in functional communication with the control system, configured such that a user from the user interface can control basic functions of the household waste shredder, such as starting and stopping the drive motor and controlling the rotational speed of the cutter discs, where the control system is further in communication with the above mentioned sensors, such that the control system will only allow the drive motor to be started, when the lid is in its closed state, and such that the control system will stop the drive motor, if the waste bin is removed from the outer container, when the motor is running.

In an embodiment of the invention, the household waste shredder comprises one or more load or resistance sensor means configured to detect if at least one of the cutter discs is/are loaded by waste material or if a resistance against the rotation of the cutter discs caused by waste material on the discs is detected, where the load sensors are in communication with the control system, such that the control system stops the drive motor, when the cutter discs have been rotating for a predetermined period of time and when the load sensors detect that the cutter discs are not loaded by waste material.

In an embodiment of the invention, the inner cylindrical container is longitudinally subdivided in sections, such that a first section closest to waste reception region has the largest diameter and that each subsequent section has a subsequently smaller diameter than the adjacent section that is situated closer to the waste reception region. Each of the sections is provided with a cutting disc with a diameter substantially corresponding to the diameter of that specific section.

In an embodiment of the invention, one or more portions of the space formed between the outer container or housing and the inner cylindrical container is filled with a sound attenuating material, thereby reducing the noise emission from the household waste shredder to the surroundings.

In an embodiment of the invention, the drive shaft is at the upper longitudinal end opposite the drive motor provided with one or more wing members extending radially outwards from the drive shaft at an angle a with the longitudinal axis L of the drive shaft. The wing members extend from the upper longitudinal end of the drive shaft and into the waste reception region and the wing members are attached to the drive shaft such that they rotate with the drive shaft. Preferably, the wing members are provided with a cutting edge configured to decompose waste introduced in the waste reception region (6) before the waste reaches the uppermost cutter disc.

In an embodiment of the invention, the angle a is in the range 30 to 60 degrees, preferably in the 40 to 50 degrees range, relative to the longitudinal axis of the drive shaft, such that the wing members extends into the waste reception region of the shredder according to the invention.

Any appropriate number of wing members could be used according to the invention, but in practical implementations, between three and six such members would be appropriate. In the detailed description of the invention, an embodiment of the waste shredder comprising four wing members is described.

By the provision of the wing members, the further advantageous effect is obtained that in the case where the user of the waste shredder according to the invention inserts waste material into the shredder in such a way that hard waste material gets into direct contact with the uppermost cutter disc, the drive motor may be unable to provide enough power to accelerate the cutter discs to the required rotational speed due to resistance between the introduced waste material and the uppermost cutter disc. According to this embodiment, waste material introduced into the waste shredder does not come into direct contact with the cutter discs until these are accelerated by the drive motor to their required rotational speed. During acceleration of the cutter discs, the introduced waste material is kept by the wing members at an appropriate distance above the cutter discs. The wing members further contribute to the shredding of the introduced waste material and to draw this material towards the cutter discs.

The waste shredder according to the present invention can be used as a stand-alone device on for example a kitchen or utility room floor. However, the waste shredder according to the invention could alternatively be incorporated into a kitchen cabinet or utility cabinet. If scaled appropriately, the waste shredder according to the invention can also be used at various places where packaging waste is a problem, such as restaurants, canteens or office facilities. The possibilities of use for the waste shredder according to the invention are numerous and the above-mentioned examples of use are by no means comprehensive.

Further advantageous features and embodiments of the invention will appear from the following detailed description of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS Further benefits and advantages of the present invention will become apparent after reading the detailed description of non-limiting exemplary embodiments of the invention in conjunction with the accompanying drawings, wherein figure 1 is a schematic representation illustrating the functional principle of the invention; figure 2 is a schematic front view of the invention with lid and waste bin closed; figures 3(a) through (d) are schematic views illustrating an embodiment of on inner cylindrical container used in the invention; figure 4(a) is an exploded view of an embodiment of a cutter disc arrangement for use in the invention; figure 4(b) is a schematic side view of an embodiment of a drive axle and motor assembly for use in the invention; figure 5 is a schematic block diagram of an embodiment of a control system for use in the invention; figure 6 is a schematic plane view showing details of an embodiment of the invention showing the upper portion of the waste shredder and the lid; figure 7 is a schematic perspective view of an embodiment of a cutter disc showing the main functional features of the cutter disc; figure 8 is a schematic representation of a second embodiment of the shredder according to the present invention, which embodiment in the waste reception region is provided with a number of wing members mounted for co-rotation with the drive shaft; and figure 9 is a schematic representation of the wing members shown in figure 8 showing as a non-limiting example the provision of four such wing members on the drive shaft. DETAILED DESCRIPTION OF THE INVENTION

The principles of the invention will be illustrated by illustrative embodiments hereof. It is however understood that a person skilled in the art may conceive other embodiments than those actually shown and described in the detailed description of the invention and that the scope of the invention is defined by the independent claims.

With reference to figure 1 there is shown a schematic representation comprising the main functional portions of a mobile household waste shredder according to the present invention. It is noted that the object of this representation is primarily to illustrate the functional principle of the invention and that practical implementations hereof may comprise further features as it will also be apparent from the more detailed description given in subsequent paragraphs.

The mobile household waste shredder of the invention is in figure 1 generally indicated by reference numeral 1 . It comprises an outer container or housing 2 that may be cylindrical, although other suitable shapes may also be used. The outer container extends longitudinally in the direction indicated by the longitudinal axis L. At the upper longitudinal end portion (as seen in figure 1 ) of the outer container there is provided a lid 3 that may be attached to the outer container via a hinge 4, such that the lid 3 can be swung open in order to introduce waste into the shredder 1 . The lid may be provided with a handle 5 facilitating opening of the lid. Preferably, the hinge is provided with a spring member that urges the lid 3 towards the closed state, as shown in figure 1 , when waste has been introduced into the shredder 1 . At the upper portion of the outer container, there is provided a waste reception region 6 into which a user can introduce waste to be shredded. Opposite the waste reception region 6, i.e. in the opposite longitudinal end portion of the outer container 2, there is provided a shredded waste reception region 21 , into which a removable waste bin 22 is inserted to collect the shredded waste 24. In figure 1 , the removable waste bin is shown introduced into the interior of the outer contained through a lateral opening in the outer container, from which it can be drawn out as indicated by the arrow A in order to empty the waste bin. To facilitate removal of the waste bin from the outer container, a handle 23 is provided on the waste bin 22. The waste bin 22 is in an embodiment provided with a safety switch, which stops the drive motor 12, if the waste bin 22 is taken out during operation. In the embodiment shown in figure 1 , the waste reception region 6 is formed as a frustum with an inclined side wall 6' and a height h, but it is understood that the waste reception region 6 could have other geometrical shapes. In a specific embodiment, the height h could be substantially equal to zero and the side wall 6' would in this embodiment be a ring-shaped region extending perpendicularly to the longitudinal axis L and with a central opening, the diameter of which could be substantially equal to the diameter of the inner cylindrical container 7.

Inside the outer container 2 there is provided a cutting device that comprises an inner cylindrical container within which there is provided a number of cutter discs 8, 9, 10. In figure 1 , three such cutter discs are provided, but it is understood that other numbers of cutter discs could alternatively be used within the scope of the present invention. The cutter discs 8, 9, 10 are mounted on a rotational drive shaft 1 1 for co-rotation with the drive shaft. The drive shaft is rotatably driven by a suitable drive means, such as an electrical motor 12. The presence of the cutter discs sub-divide the interior region of the inner cylindrical container 7 in subsections 13, 14, 15, 16 as shown in figure 1 .

The cutter discs are provided with suitable cutting members such as blades or knives 8', 9' and 10', respectively, and the number and geometrical layout of the blades or knives can be chosen such that the uppermost cutter disc 8 provides a course shredding of the waste material, the next cutter disc 9 provides a finer shredding and the lowermost cutter disc 10 provides the finest shredding of the waste. The waste material to be shredded enter the uppermost subsection 13 of the inner cylindrical container 7 from the waste reception region 6 and the shredded waste leaves the inner cylindrical container 7 through the lowermost subsection 16 and enters an exit region 19 located beneath the inner cylindrical container 7. The inner cylindrical container 7 may be configured to rest on a laterally extending platform 17 provided in the interior region of the outer container 2. The exit region 19 may for instance be bounded by of conical receptor 18 resembling a funnel, although other configurations may of cause alternatively be used.

From the exit region 19, the shredded waste enters the shredded waste reception region 21 though an opening 20, which may for instance be provided in the conical wall portion of the receptor 18.

Ultimately, the shredded waste gravitates downwards to the removable waste bin 22 describes above.

When the blades or knives 8', 9' and 10' in the respective cutter discs 8, 9 and 10 rotate they generates an air flow downwards through the inner cylindrical container, i.e. from subsection 13 through subsections 14, 15 and 16 and via the exit region 19 and the opening 20 to the shredded waste reception region 21 . Hence, an air pressure buildup will occur in the shredded waste reception region 21 , when the cutter discs rotate. In order to relieve this pressure buildup, a passageway 26 is provided between the shredded waste reception region 21 and the waste reception region 6. In the illustrative representation given in figure 1 , this passageway 26 is formed as a tube running through the gap formed between the inner cylindrical container 7 and the outer container or housing 2, but various other forms of suitable air passage ways may alternatively be used. Between the shredded waste reception region 21 and the tube 26 there is provided a filter that is designed to prevent shredded waste from being drawn by the generated air flow through the tube 26 and back into the waste reception region 6. The tube exits in an opening 28 into the waste reception region 6.

In an alternative embodiment, the air passageway 26 running in the gap between the inner cylindrical container 7 and the outer container or housing 2 is replaced by an air inlet opening provided either in the lid 3 or in the waste reception region 6 allowing air to be sucked in through the air inlet opening from the surroundings. An air outlet opening is in this this embodiment provided at a suitable location leading from the shredded waste reception region 21 through the wall of the outer container 2 and to the surroundings. By this arrangement it is ensured that air can flow through the inner cylindrical container 7 without an undesired air pressure buildup downstream of the cutter discs 8, 8, 10 and a corresponding pressure drop upstream of the cutter discs.

In another alternative embodiment, the gap formed between the inner cylindrical container 7 and the outer container or housing 2 is used as an air passageway leading from the shredded waste reception region 21 to the waste reception region 6.

In any of the alternative embodiments described above, means (such as a filter) must be incorporated to ensure that shredded waste material collecting in the shredded waste reception region 21 is not recirculated to the waste reception region 6.

The inner cylindrical container 7 serves a number of purposes. Thus, it provides a well-defined channel through which the waste material is forced to pass through the different cutter discs from the waste reception region 6 to the exit region 19. Further, the inner cylindrical container 7 prevents the cutter discs from lateral movement, as the outer circumferential diameter of the cutter discs substantially corresponds to the inner circumferential diameter of the inner cylindrical container. Thus, a contact surface is established between respective cutter discs and the inner circumferential surface of the inner cylindrical container. In a presently preferred embodiment, the outer circumferential edge portion of the individual cutter discs is provided with a roller bearing arrangement that ensures a sufficiently smooth and tight contact between the cutter discs and the inner wall of the inner cylindrical container. It is however noted that a number of alternatives to the roller bearing arrangement may be conceived without departing form the scope of the claimed invention.

With reference to figure 2(a), (b) (c) and (d) there is shown an embodiment of the inner cylindrical container used in the present invention. Although the inner cylindrical container could be formed as an unbroken cylindrical body, it is advantageous to be able to open the cylinder (e.g. to enlarge its diameter somewhat) in order to remove it from the cutter discs for instance to facilitate cleaning, repair or replacement of cutter discs.

With reference to figure 2 there is shown a schematic front view of the invention with the lid 3 and the waste bin 22 closed. In the region 29 between the lid 3 and the outer container 2 there may be provided sealing means configured to provide an air-tight sealing between the lid and the upper edge portion of the outer container. In the embodiment shown in figure 2, the outer container 2 that provides the housing of the waste shredder is cylindrical, but it is understood that other shapes of the outer container/housing could be used within the scope of the invention. The outer container 2 is in this embodiment provided with a user control means 30 comprising press buttons 31 , 32, a dial 33 and a display 34. Other control elements may be provided on the user control means 30, if required. An embodiment of an embodiment of a control system for use in the invention will be described in connection with figure 5 below. From the user control means 30, a user is able to control for instance the rotational speed of the cutter discs (for instance by means of the dial 33) and start and stop of the waste shredder. The display 34 shows information on the various functional aspects of the waste shredder. A child safety code is an optional program feature in the operating system of the control system of the waste shredder according to the invention.

With reference to figures 3(a) through (d), an embodiment of an inner cylindrical container for use in the invention are schematically shown. As described above in connection with figure 1 , the diameter of the cutter discs 8, 9, 10 substantially equals the inner diameter of the inner cylindrical container 7 and in case the inner cylindrical container 7 has to be removed from the cutter discs, it is advantageous if the diameter of the inner cylindrical container can be increased somewhat. This is made possible by the embodiment of the inner cylindrical container shown in figures 3(a) through (d), where a longitudinally extending slit 37 is formed in the inner cylindrical container by overlapping edge portions 35 and 35 of the inner cylindrical container. To open and close the inner cylindrical container, there is in the shown embodiment provided opening/closing means 38 in the region of the longitudinal slit 37. With reference to figures 4(a) and (b), an embodiment of a cutting mechanism according to the invention is shown. This mechanism comprises (as in figure 1 ) three cutter discs 8, 9, 10, but it is understood that more or less cutter discs might be used, if desired. The main features of the cutter discs will be described below in connection with figure 7. Each individual cutter disc is mounted for co-rotation with the drive shaft 1 1 , which drive shaft is longitudinally subdivided in three sections 40, 41 , 42 provided with fastening means 43, 44, 45, 46, 47 and 48 configured for releasable attachment of the respective cutter disc to the drive shaft at the appropriate longitudinal position hereon. The drive shaft is coupled to the drive motor 12 that - when activated - rotates the drive shaft and the cutter discs. The cutter discs are fastened to the drive shaft by suitable means collectively indicated by reference numeral 39.

With reference to figure 5 there is shown a flow chart illustrating a basic operational process of an embodiment of the household waste shredder according to the invention. It is noted that when reference to a "button" or the like is made in the following, this could be a physical button provided on the waste shredder, but it could also be a "graphical button" for instance an icon on a touch screen on the user interface means 30.

Initially, the lid 3 is opened by activating the lid open button (49) after which the waste material to be shredded can be introduced in the waste reception region 6 of the waste shredder. The lid is then closed (manually) and the start button (50) is activated. This will start the drive motor provided the various safety sensors 66, 67, etc. does not counteract this, such as when for instance the waste bin (22) is not correctly inserted in the waste shredder. This is illustrated in figure 5 by functional blocks 51 , 52, 54, 55, 56, 57, 58 and 59. In functional block 60, the rotational speed of the drive motor 12 can be controlled.

The rotating cutter discs 8, 9, 10 will shred the packaging refuse and a moment later the drive motor (12) will stop when there is no more resistance from waste material to the rotation of the cutter discs. The waste bin (22) can now be emptied into the normal garbage system. The lid 3 can open, when the open button 49 is activated. However, a code is required if a children safety program is used, which is an optional feature accessible from the user interface means (30). With reference to figure 6 there is shown a schematic plane view showing details of an embodiment of the invention showing the upper portion of the waste shredder 1 and the lid 3. In figure 6, the waste shredder is seen from above with the lid 3 in its open position. The lid 3 is attached to the body of the outer container 2 via a hinge element 4 that in the shown embodiment comprises a spring arrangement configured to urge the lid 3 towards the open state. Consequently, the lid remains open, until the user manually closes the lid.

Inside the outer container 2 there is provided the cylindrical inner container 7 that in the shown embodiment is provided with a grip 63 in order to facilitate removal of the inner cylindrical container 7 from the waste shredder. Figure 6 also shows the user control means 30 and the dial 33 hereon.

The upper edge portion of the outer container 2 is in the shown embodiment provided with an edge portion 71 extending radially a certain distance towards the inner cylindrical container 7. A similar edge portion 72 is provided in the edge region of the lid 3 facing the outer container 2. In the respective edge portions 71 and 72 there is provided a locking mechanism 64 and 65 that locks the lid 3 to the outer container when required. A number of sensors 66 are provided in the edge portion 71 and at corresponding locations in the edge portion 72. These sensors register if the lid 3 is in its closed or open position.

The exit opening 28 of the air passageway described above in connection with figure 1 is also shown in figure 6. In the illustration given in figure 1 , the exit opening 28 exited into the inner cavity formed by the lid, but a configuration as shown in figure 6 could alternatively be used, in which the lid 3 is provided with a separate air passageway 69 with an inlet opening 68 corresponding to the exit opening 28 and an outlet 70 directed towards the upper end of the inner cylindrical container 7, when the lid 3 is in its closed state. The outlet 70 may be of smaller diameter than the diameter of the inner cylindrical container 7 or of substantially the same diameter. With reference to figure 7 there is shown a schematic perspective view of an embodiment of a cutter disc showing the main functional features of the cutter disc. The cutter disc comprises a central hub portion 72 designed to be placed at the appropriate position on the drive shaft. At the outer circumferential edge portion of the cutter disc there is provided a tubular member 74, the outer circumferential surface 75 of which provides a contact face against the inner circumferential surface of the inner cylindrical container. Radially between the hub portion 72 and the tubular member 74 the cutter blades 73 extend in such a manner that a through passage 76 is formed between adjacent cutter blades. As it appears from figure 7, the cutter blades 73 are tilted about a radial axis, such that a cutting edge 77 is formed at a leading edge of the cutter blade 73 and such that - when the cutter disc is rotating - an air flow will be generated through the passages 76 in the direction indicated by the arrow F.

With reference to figure 8 there is shown a schematic representation of a second embodiment of the shredder according to the present invention, which embodiment in the waste reception region is provided with a number of wing members 78, 79 mounted at (or in the vicinity of) the upper end 84 of the drive shaft 1 1 for co-rotation with the drive shaft 1 1 . In figure 8 two such wing members are shown, but (as exemplified by figure 9) other numbers of wing members may be used. The wing members form an angle a with the longitudinal axis L and extend into the waste reception region 6 of the shredder. With reference to figure 9 there is shown a schematic representation of the wing members shown in figure 8 showing as a non-limiting example the provision of four such wing members on the drive shaft. In figure 9, four wing members 80, 81 , 82, 83 are shown extending from the drive shaft 1 1 . Although the wing members shown in figures 8 and 9 are of equal length and extend at equal angles a relative to the longitudinal axis of the drive shaft it is understood that the wing members my have different lengths and/or may extend at different angles a from the drive shaft. Although the invention has been explained in relation to the embodiments described above, it is to be understood that many other possible modifications and variations can be made without departing from the scope of the present invention.