Patent Publication Number: US-8985838-B2

Title: Stick mixer

Description:
FIELD OF THE INVENTION 
     The invention relates to kitchen appliances and more particularly to a hand held electric mixer. 
     BACKGROUND OF THE INVENTION 
     Stick mixers are well known in domestic and commercial kitchens. Electric hand mixers have particular safety requirements and some of these are imposed by legislation. Hand mixers also have ergonomic requirements. The present invention seeks to address both the safety and ergonomic requirements of a stick type mixer. 
     The rotating blade of a stick mixer is contained within a bell housing. The rotational motion of the blade creates suction. If the suction is excessive, the mixer will draw itself against a flat surface such as the bottom of a container or bowl. When the bottom edge of the bell housing is urged excessively against a surface, the mixing efficiency is diminished and the user loses a certain degree of control over the motion of the mixer. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     It is an object of the invention to provide a hand held stick type mixer that is comfortable to hold and that satisfies the appropriate safety requirements. 
     It is another object of the invention to provide a hand held stick type electric mixer that has a pistol like grip. 
     It is also an object of the invention to provide a hand held stick type mixer that has a blade housing with an interior sidewall below a floor, having a distance across a transverse axis that is smaller than a distance across a perpendicular axis. Void space in the housing may have ribs. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
       In order that the invention be better understood, reference is now made to the following drawing figures in which: 
         FIG. 1  is a perspective view of a stick mixer in accordance with the teachings of the present invention; 
         FIG. 2  is a side elevation of the stick mixer shown in  FIG. 1 ; 
         FIG. 3  is a bottom plan view of the mixer depicted in  FIGS. 1 and 2 ; 
         FIG. 4  is a top plan view of the mixer depicted in  FIGS. 1 and 2 ; 
         FIG. 5  is a perspective view of a mixing bowl and jug; 
         FIG. 6  is a perspective view of the mixing bowl and jug of  FIG. 5  in an assembled configuration; 
         FIG. 7 ; is a perspective view of a mixing bowl, jug and combination base and lid; 
         FIG. 8  is a side elevation of a second embodiment of a bell housing; and 
         FIG. 9  is a third embodiment of a bell housing according to the teachings of the present invention. 
     
    
    
     BEST MODE AND OTHER EMBODIMENTS 
     As shown in  FIG. 1 , a hand held stick mixer  10  comprises a bell housing  11  for a rotating blade, a stem  12 , a motor housing area  13  and a grip  14 . As suggested in  FIGS. 1 and 2 , the hand held stick mixer of the present invention comprises a pistol-like grip  14 . The grip is considered pistol-like because the mixer&#39;s on-off switch  15  protrudes away from the remainder of the grip area  16  and because the switch  15  is intended to be activated by the index finger. The remainder of the grip area  16  provides a convenient location for the middle finger, ring finger and pinky. The middle finger fits under a shelf  7  and a slight concavity  18  accommodates the thumb. The concavity  18  preferably extends to either side of the switch  15  resulting in an hourglass shape centred around the switch  15 . The index finger protrusion or trigger protrusion  19  forms a head  20 . The head is the uppermost part of the mixer and the uppermost part of the handle. The upper surface of the head comprises a rotating or other style speed adjustment or knob  21  and a flexible conduit for the electrical cord  22 . The rear edge  23  of the grip and the areas adjacent to it comprise a palm contacting portion that is smooth and continuous from below the drip area to the transition  25 . 
     As shown in  FIG. 2 , the rear surface  23  of the grip tapers toward the longitudinal centre line  24  and transitions smoothly  25  as it approaches the cord outlet  22 . This provides a smooth and comfortable area to receive the web of skin that exists between the thumb and index finger of the user. With reference to the vertically orientated mixer shown in  FIG. 2 , a horizontal bands  26  located between the top and the bottom of the head  20  comprises a generally concave area comprising the aforementioned concavities  18  for receiving the thumb as well as a distinctly concave area  27  for receiving the index finger. In preferred embodiments, the concavity  27  further comprises an elastomeric membrane below which is located an electric switch that operates the motor. That switch operates in conjunction with the speed controller  21  to determiner the rotational speed of the blade (not shown) located within the bell housing. Particularly with reference to the areas above and below the switch and/or its protective membrane  27 , the head comprises a pair of protective flanges  28 ,  29 . With reference to the left side vertical elevation shown in  FIG. 2 , the protective flanges  28 ,  29  protrude past the switch and/or its protective membrane  27  and the switch and/or protective membrane extend past the grip area  16  intended to receive the middle, ring and pinky fingers. Thus the switch  15  is protected by the flanges  28  and  29  so that the switch can not be tripped with a 40 mm ball as known from safety standards. The lower area of the motor housing  13  also preferably protrudes beyond the portion of the grip  16  intended to receive the middle, ring and index fingers. 
     From a user&#39;s perspective, the stick mixer of the present invention comprises two major sub-assemblies. The upper assembly  30  includes the grip, the motor housing  13  and the user operable coupling components  31  that are used to removably attach the upper assembly from the lower assembly  31 . The lower assembly comprises a coupling portion  32  that is generally round in cross section, a bell housing  11  that is generally oval in cross section and a stem  12  that is also generally oval in cross section and that interconnects the coupling portion  32  with the bell housing  11  using preferably smooth transitions  33 ,  34 . 
     As shown in  FIG. 2 , the bell housing  11  preferably comprises a polymeric body having a stainless steel skin. The un-skinned lower (and preferably polymeric) edge  35  of the bell housing further comprises one or more relief areas  36  that interrupt the lowermost circumference of the bell housing  11 . Also visible in  FIG. 2  is the terminal end  37  of a rotating drive shaft that carries the mixer&#39;s blade (not shown). 
     As shown in  FIG. 3 , the bell housing  11  is generally oval in cross section. An oval, an oval with flat sides, or an ellipse shape may be used. The oval (or ellipse) cross section of the stem  12  and its concentric relationship to the cross section of the bell housing is demonstrated in this drawing figure. The rotating shaft  37  is central to both the stem  12  and the bell housing  11 .  FIG. 3  illustrates the lowermost edge or circumference  35  of the bell housing as well as the interior  37  of the bell housing  11 . The interior comprises an interior side wall  38  defined by the interior side wall of the bell housing and its recess or recesses  36  and an optional interior floor  39  through which protrudes the shaft  37  (see  FIG. 2 ). Because the bell housing interior sidewall  38  is oval (or ellipsoid) in cross section, the internal distance across the transverse axis  40  is smaller than the distance across a perpendicular axis  41 . The interior of the bell housing, particularly at the level of the blade and below it (can be seen from  FIG. 3 ) to resemble a symmetrically truncated circle or, for example, a rectangular middle part with or bounded by arcuate ends, those arcs approximating or being an arc of a circle. The ends may also alternately be semi-circular. The internal dimension along the transverse axis  40  is essentially determined by the diameter of the rotating blade and the required clearance for it. The internal dimension along the transverse axis  40  need only provide a blade clearance of a few millimeters. The rotating blade sweeps a circle with a diameter indicated by the dotted line  42  in  FIG. 3 . Any area in the horizontal plane that is not simply clearance for the rotating blade is indicated by the shading  43  and is referred to as void space. It will be observed that there is very little void space adjacent the transverse axis  40  and that there is more void space adjacent to the perpendicular axis  41 . Thus, the amount of void space and its location within the bell housing corresponds generally to how the oval shape of the bell housing deviates form the circular swept path of the mixer&#39;s blade. The void space provides improved performance and room for the rib or ribs  44 . 
     As shown in  FIGS. 2 and 3 , one or more ribs or turbulators  44  can be located within the bell housing  11 . In these examples, the turbulators or ribs  44  are two in number and are located in alignment with the perpendicular axis  41 . The ribs extend from close to the lower edge  35  to above the blade and toward the optional interior floor  39 . The ribs only occupy the void space and do not interfere with the rotation of the blade. The ribs only need be thick enough to withstand the hydrodynamic forces within the interior of the bell housing without distorting. One, two or more ribs may be used. The ribs disrupt the swirling flow within the bell housing (particularly in the void space) and have been observed to reduce the suction generated by the rotating blade. This produces a more predictable feel for the user and reduces the extent to which the lower edge  35  of the bell housing can be adhered to a surface by virtue of the action of the rotating blade. 
     As shown in  FIG. 3 , an interior sidewall  38  is a peripheral sidewall that defines an elongate profile in horizontal cross section. This embodiment interior sidewall, in horizontal cross section, forms a pair of parallel straight side portions that each transition into arcuate end portions to adjoin respective ends of the parallel straight side portions. In this embodiment, the arcuate end portions are located about a perpendicular axis, and the side portions are parallel to the perpendicular axis. 
     As shown in  FIGS. 5 and 6 , accessories for a stick mixer may include a co-operating chopper  50  and jug  51 . The chopper  50  comprises a chopping vessel  52  that fits into and engages with the open mouth  53  of the jug  51 . The chopping vessel  52  is generally cylindrical and preferably transparent. It has a lid  54 . The lid  54  has an integral receptacle  55  for the upper assembly  30 . The features of the receptacle  55  are intended to co-operate with the coupling features of the upper assembly  30 . In this way, the output shaft of the upper assembly  30  can be used to drive a rotating chopper  56  that spins within the vessel  52 . In this example, the rim area  57  of the vessel  52  is provided with an external, integral, polygonal, coupling ring  58 . The integral coupling ring  58  engages a polygonal internal receiving ring  59  located around the interior of the mouth  60  of the jug  51 . 
     In this example, the jug  51  is generally cylindrical, preferably transparent and has a grip or handle  61 . The clearance between the coupling ring  58  and the receiving ring  59  is loose enough that the vessel  52  can be inserted and withdrawn easily. However, the clearance is close enough that the vessel  15  will not rotate with respect to the jug  51  once the coupling ring  58  and receiving ring  59  are engaged. The engaged configuration is shown in  FIG. 6 . The nesting between the jug and the vessel is useful for storing these accessories but also provides a convenient way of gripping the assembly of these two components for actual use in conjunction with the upper assembly of a stick mixer. 
     As shown in  FIG. 7 , a polymeric lid  70  is adapted to function as both a base and a lid for either or both of the chopper  50  or jug  51 . The lid  70  comprises a top  71  and an upright internal rim  72 . The lid also features a pull-tab  73  with a finger-sized opening  74 . In preferred embodiments, the upright rim  72  fits snugly within the internal receiving ring or mouth  59  of the jug and also within the mouth  75  of the chopper or mixer  50  in the same way that it receives its lid  54 . Because both the chopper  50  and the jug  51  are tapered (larger diameter at the top, smaller diameter at the bottom) the internal surface  76  of the rim  72  is adapted to receive the bottom of either or both of the jug  51  or chopper  50 . The lid  70  also has a flange  77  that extends outwardly from the rim  72 , the flange  77  acting to improve the seal when it is used as a lid and better cover the upper extremity of the vessel on which it is placed. The lid is preferably fabricated from a flexible, non-slip polymer. 
     Alternate embodiments of the bell housing  80  are depicted in  FIGS. 8 and 9 .  FIG. 9  illustrates how a through opening  81  may be formed one or both sides of the oval shaped bell housing  80  by utilisation of a bridge  82  across the lower extent of one or both relief areas  36  (as shown in  FIG. 2 ). The size or area of the opening  81  can be altered to suit the characteristics of the rotating blade, as required. Anther method of introducing openings into the interior of the bell housing is shown in  FIG. 9 . In this example, one or more through openings  91  are provided below the internal floor  93 . In the example of  FIG. 9 , two openings  91 ,  92  are located in the housing  180  degrees or diametrically opposed from one another. 
     While the present invention has been disclosed with reference to particular details of construction, these should be understood as having been provided by way of example and not as limitations to the invention as it may be expressed in the claims.