Abstract:
The present invention relates to an automatic stirring system that is selectively mounted to a cooking vessel. The cooking vessel includes a handle, an opening for receiving food items, and a lid. The automatic stirring system includes a housing mounted to the handle, a ring gear rotatably mounted to the cooking vessel, a drive assembly for rotating the ring gear, and at least one stirring vane attached to the ring gear. In various other embodiments, the automatic stirring system includes at least one forward swept stirring vane, at least one aperture in the stirring vane, a variable speed control unit, and a component orientation that provides substantially unimpeded access to the opening of the cooking vessel.

Description:
FIELD OF THE INVENTION 
   The present invention relates to the art of stirring systems used in the preparation of food items. In particular, the present invention involves an automatic stirring system that may be mounted to a conventional cooking pot, vessel, or pan. 
   BACKGROUND 
   In preparing various food items a common step usually involves stirring any number of ingredients together. In some cases the stirring process must be done continuously as is common in the preparation of certain soups, sauces, and puddings. If due to any number of reasons the stirring process is neglected, avoided, or abandoned, the food item may become burnt because of localized overheating of the food mixture. At the very least, a lack of stirring will result in a non-homogenous food product that is unevenly cooked thereby having an inconsistent taste. It is likely that the resulting food item will be offensive to the user or cook and will end up being thrown away. 
   While stirring systems that stir the contents of a cooking vessel are known, they exhibit many disadvantages. One disadvantage involves the overall size and complexity of these systems. Some systems require a physical and permanent installation either to the cooking surface, a wall surface, or the cooking vessel itself. These permanent type installations are unattractive and often consume precious work space. Another disadvantage involves the proximity of the stirring elements to the cooking vessel. Often the stirring elements neglect to fully agitate the food mixture that may become attached to the inner wall and bottom surfaces of the cooking vessel. Yet another disadvantage relates to the design of the stirring elements. Most stirring elements are generally flat. As explained herein, a flat stirring element is less effective at stirring because it tends to push fluid and other food items toward the center of the cooking vessel. This may result in a swirling vortex where only certain ingredients will be mixed. Still another disadvantage involves the overall orientation of the various components required to stir the contents of the cooking vessel. Most stirring systems consume most if not all of the opening of the cooking vessel. This makes it extremely difficult for the user to observe, add ingredients to, or remove portions of the food mixture while these stirring systems are attached or operating. Yet another disadvantage involves the user&#39;s ability to adjust the speed of the stirring system of the system. Some systems may offer various speed settings, however, these speed settings are often too slow or too fast to obtain optimal mixing. 
   Therefore, it is the object of the present invention to provide an improved automatic stirring system. 
   SUMMARY OF THE INVENTION 
   The present invention relates to an automatic stirring system that offers a variety of improvements over other prior art stirring systems. 
   In a first embodiment, the automatic stirring system is designed to be selectively mounted to a common household cooking vessel. The automatic stirring system generally includes a housing, a drive assembly, and a stirring vane assembly. The housing is adapted to be mounted on a handle of the cooking vessel. The drive assembly, which is disposed internally to the housing, includes a power source, a variable speed control unit, a DC motor, and a transmission with an output drive gear. The stirring vane assembly includes a pair of forward swept stirring vanes and a beveled ring gear. The drive gear engages the ring gear of the stirring vane assembly. The ring gear is rotatably mounted about an opening of the cooking vessel. The stirring vanes are disposed internally to the cooking vessel and come into close proximity with an inner wall surface and a bottom surface of the cooking vessel. 
   The first embodiment of the automatic stirring system offers several advantages. One advantage involves the close fitting stirring vane assembly. As the stirring vanes rotate, substantially all of the food mixture in the cooking vessel is agitated. This includes the food mixture which clings to both the inner wall surface and the bottom surface of the cooking vessel. Another advantage involves the forward swept design of the stirring vanes that prevents the food mixture from collecting in the center of the cooking vessel and enhances homogenous mixing of the food mixture. Yet another advantage of the first embodiment involves the use of the variable speed control unit. The variable speed control unit allows the user to adjust the speed of the unit as the consistency of the food mixture changes. Still another advantage involves the orientation of the drive assembly and stirring vane assembly to allow substantially unimpeded access to the opening of the cooking vessel. This allows the user to easily add ingredients or remove the food mixture as necessary even while the stirring system is installed or operating. 
   In another embodiment, the speed control unit of the drive assembly includes a speed sensor such that the output speed of the motor or the beveled gear is monitored. As load on the stirring vane assembly changes, the speed sensor enabled speed control unit would adjust the power to provide a constant output speed of the drive assembly. 
   In yet another embodiment, the automatic stirring system would include an aluminum or stainless steel housing, ring gear, and stirring vanes to increase the durability and longevity of the automatic stirring system. 
   In still another embodiment, various sized stirring vane assemblies would be driven by one interchangeable housing and drive assembly unit. Therefore, one housing and drive assembly unit could be used to drive the stirring vanes of different cooking vessels. 
   In yet another embodiment, the ring gear is designed to include an additional inner flange to allow the lid of the cooking vessel to sit on top of the ring gear. This would allow the cooking vessel to be capped as if the automatic stirring system were not installed on the cooking vessel. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention may take form in certain structures and components, several embodiments of which will be described in detail in this specification and illustrated in the accompanying drawings. In the drawings: 
       FIG. 1  is a perspective view of a first embodiment of an automatic stirring system according to the present invention. 
       FIG. 2  is a perspective view of a prior art cooking vessel. 
       FIG. 3  is a side view of the first embodiment of the automatic stirring system illustrating the installation of the automatic stirring system onto the prior art cooking vessel. 
       FIG. 3A  is a side view of the first embodiment of the automatic stirring system showing an enlarged detail view illustrating the engagement of a drive gear and a ring gear. 
       FIG. 4  is a cross sectional view of the first embodiment of the automatic stirring system illustrating a drive assembly and a stirring vane assembly. 
       FIG. 5  is a perspective view of the stirring vane ring gear assembly of the first embodiment of the automatic stirring system. 
       FIG. 6  is a top view of the stirring vane assembly of the first embodiment of the automatic stirring system. 
       FIG. 7  is a side view of the stirring vane assembly of the first embodiment of the automatic stirring system. 
       FIG. 8  is a perspective view of a second embodiment of an automatic stirring system according to the present invention. 
       FIG. 9  is a top view of the automatic stirring system of  FIG. 8  illustrating an integrated drive assembly having a right angle drive. 
   

   DETAILED DESCRIPTION 
   With reference to  FIG. 1 , a first embodiment of an automatic stirring system  100 -is shown. The stirring system  100  generally includes a housing  110 , a drive assembly  120  ( FIG. 5 ), and a stirring vane assembly  135 . The stirring vane assembly  135  includes a ring gear  140  and a pair of stirring vanes  160 . 
   With reference to  FIGS. 1 and 2 , the housing  110  is adapted to attach to the upper portion of an existing handle  12  of a cooking vessel or sauce pan  10 . The cooking vessel  10  includes a lid  16 , an inner wall surface  18  and an inner bottom surface  20 . In addition, the handle  12  includes at least one aperture  14 . The housing  110  of the automatic stirring system is designed to engage the aperture  14  of the handle  12  of the cooking vessel  10 . Also, the ring gear  140  and stirring vanes  160  are adapted to fit within the cooking vessel  10 . Specifically, the stirring vanes  160  are designed to come into close proximity with the inner wall surface  18  and the inner bottom surface  20 . The cooking vessel  10  is generally representative of prior art cooking vessels. 
   Now with references to  FIGS. 3-4 , a side view of the first embodiment of the automatic stirring system  100  as installed on the prior art cooking vessel  10  is shown. The housing  110  of the automatic stirring system  100  is mounted to the handle  12  of the cooking vessel  10 . The housing  110  includes a pair of attachment points. The first attachment point consists of a downwardly projecting boss  112   a  which engages a distal aperture  13  along the handle  12 . A second attachment point consists of a threaded knob  112   b  which engages a stem through a proximal aperture  14  in the handle  12 . The threaded knob  112   b  acts to secure the housing  110  to the handle  12  whereas the boss  112   a  prevents the housing  110  from translating in a lateral direction along a top surface of the handle  12 . The housing  110  further includes a guide lip  114 , a speed control knob  116  and a drive assembly compartment  118 . 
   With continuing reference to  FIG. 4 , a cross section of the drive assembly  120  is also shown. The drive assembly  120  generally includes a power source  122 , a prime mover or motor  124 , a transmission  126  having a drive gear  128  and a variable speed control unit  130 . The power source  122  may consist of a battery or an external AC to DC power adapter. The power source  122  is operatively connected through the speed control unit  130  to a DC motor  124 . The motor  124  is then operatively connected to the transmission  126  which reduces the output speed (or RPMs) of the motor, but increases the available torque. The low RPM and high torque is transmitted to the ring gear  140  via the drive gear  128 . The drive gear may be beveled to increase contact area between it and the ring gear. The speed control unit  130  may be a rheostat, switching power transistor, MOSFET, pulse-width modulation (PWM), or any other power regulating device. Regardless of the technique used to regulate the power supplied to the motor  124 , the motor  124  will have an infinite range of speed settings from very low RPM through the top speed of the motor  124 . Alternatively, the speed control unit  130  may provide high/medium/low type speed settings or take the form of a simple on/off switch. 
   In the first embodiment, the transmission  126  takes the form of a planetary gear reduction set. The planetary gear reduction set provides a very high gear ratio in a very compact space as is necessary for the transmission  126  to fit within the drive assembly compartment  118  of the housing  110 . As the drive gear  128  rotates, the teeth of the drive gear engage a plurality of teeth  146  of the ring gear  140  to cause the ring gear to rotate in either a clockwise or counterclockwise direction. Since the first embodiment  100  uses a DC motor  124 , it is extremely easy to reverse the polarity of the motor  124 , thereby reversing the direction of the stirring vane assembly  135 . However, because the forward swept design of the stirring vane  160  is optimized to rotate in the counterclockwise direction (as viewed from the top in  FIG. 6 ), reversing the direction of the ring gear would not be as beneficial. Because the drive gear  128  shown in  FIG. 4  is beveled, the torque which is transmitted through the drive gear  128  into the ring gear  140  will also result in a thrust force extending radially inward toward the ring gear  140 . Because of this thrust load, the guide lip  114  of the housing  110  or another retention device is necessary to maintain positive contact between the teeth of the drive gear  128  and the teeth  146  of the ring gear  140 . In order to do so, the guide lip  114  engages a guide track  150  of the ring gear  140 . In addition, the guide lip  114  provides a mechanism for restraining the stirring vane assembly  135  within the cooking vessel  10  by continuously maintaining a small downward thrust load along an upper thrust surface  148  of the ring gear  140 . Between the guide lip  114  and the cooking vessel  10 , a lower thrust surface  149  prevents the stirring vanes  160  from rubbing excessively up against the bottom surface  20  of the cooking vessel  10 . 
   Now with reference to  FIG. 5 , a perspective view of the ring gear  140  and the stirring vane assembly  135  of the first embodiment is shown. As mentioned previously, the ring gear  140  includes the plurality of beveled gear teeth  146 , the guide track  150 , the upper thrust surface  148  and the lower thrust surface  149  ( FIG. 6 ). In the first embodiment, the stirring vane assembly  135  involves two stirring vanes  160 , each vane being oriented 180° apart from the other. The stirring vanes  160  include a leading surface  162  and a trailing surface  164 . In addition, the stirring vane  160  may include one or more apertures  166  which extend generally perpendicular to the leading surface  162  and the trailing surface  164 . The general purpose for the apertures  166  are to allow various flow paths either directly through the stirring vane  160  or over an upper edge  170  of the stirring vane  160 . As the stirring vanes  160  rotate through a mixture of solids and fluids contained in the cooking vessel, some of the mixture will flow through the vanes  160  and some will flow over or around the vanes  160 . In addition, the stirring vanes  160  further include a gusset  168  to provide stiffening along an outer edge  172  of the stirring vanes  160 . The gussets  168  are adhered, molded, fastened or otherwise secured to the ring gear  140  at an upper portion of the stirring vanes  160 . 
   Now with reference to  FIG. 6 , a top view of the stirring vane assembly  135  of the first embodiment is shown. Also shown are the plurality of ring gear teeth  146 , the guide rib  150  and the upper thrust surface  148 . More importantly,  FIG. 6  clearly illustrates the forward swept design of the stirring vanes  160 . As mentioned previously, the stirring vanes  160  in the first embodiment are intended to rotate in a counterclockwise direction. The forward swept design coupled with the counterclockwise rotation of the stirring vanes  160  has the effect of cupping or retaining the mixture of solids and fluids immediately in front of the leading surface  162  of each respective stirring vane  160 . This cupping effect prevents the mixture from escaping either inward toward the center of the cooking vessel or outward towards the inner wall of the cooking vessel. It is also important to note that the stirring vanes  160  do not connect at a center portion indicated by reference numeral  181 . Because each stirring vane  160  is independent, this allows the mixture to communicate from a first side or hemisphere  180  to a second side or hemisphere  182 . Furthermore, the apertures  166  provide additional mixing of ingredients that are added to or within the cooking vessel. In addition, and as best shown in  FIG. 6 , each of the respective stirring vanes can be angled rearwardly (i.e., tilted or angled in a rearward direction such that the leading surface of the stirring vane is visible from a top or plan view). 
   Had the design of the stirring vanes  160  been substantially flat and straight, such that the stirring vanes followed a radial (as indicated by the x axis in  FIG. 6 ) between the inner wall and the center  181  of the cooking vessel, the stirring and mixing effect would be significantly impaired. A design using straight or flat stirring vanes would tend to cause the mixture to naturally progress from the inner wall towards the center  181  of the cooking vessel. This progression would occur because as the flat stirring vane would move through the mixture, the mixture would become trapped between the inner wall surface of the cooking vessel and the flat leading surface of the stirring vane. Because the mixture would be restricted, a slightly higher pressure would result near the leading surface of the vane and the inner wall surface, thus, urging the mixture toward the center  181  of the cooking vessel. As the mixture flows toward the center  181  a swirling vortex may form where only certain less dense ingredients will be mixed. However, the forward swept design of the stirring vane  160  of the first embodiment  100  prevents this from occurring. 
   With continuing reference to  FIGS. 5-6 , as the mixture encounters the leading surface  162  of the forward swept stirring vane  160 , the mixture tends to gravitate towards a middle location  161   b  of the stirring vane  160 , rather than toward the center  181 . This occurs because the mixture encounters an even greater resistance (or pressure) due to the increasing inclination of the forward swept stirring vane  160 . Using a typical X-Y reference whose positive X axis is located along a length of the stirring vane  160 , the inclination (or instant slope) of the stirring vane  160  changes from a positive slope at a root location  161   a , to a zero slope near the middle location  161   b , to a negative slope at a tip location  161   c . As the mixture encounters the leading surface  162 , the mixture naturally progresses towards the region of zero slope (location  161   b ) rather than escaping immediately around the tip location  161   c . Thus, the mixture tends to stay in front of the stirring vane  160  rather than progressing towards the center  181 . 
   With reference to  FIG. 7 , a side view of the stirring vane assembly  135  of the first embodiment is shown. The lower thrust surface  149  of the ring gear  140 , as well as the leading surface  162  and the trailing surface  164  of the stirring vanes  160  are clearly illustrated. Also, the apertures  166  in the stirring vanes  160  are clearly visible, as well as the upper edge  170  and the outer edge  172  of the stirring vane  160 . Once again, it is important to note that the outer edges  172  and the bottom edge surface  174  of the stirring vanes  160  come within very close proximity to the inner wall surface  18  and the inner bottom surface  20 , respectively, of the cooking vessel. This prevents any partially cooked mixture of the fluids or solids from sticking to the bottom surface  20  or the inner wall surface  18  and further ensures a homogeneous consistency of the mixture. 
   With reference to  FIGS. 1-4 , the installation of the automatic stirring system  100  onto a prior art cooking vessel  10  is relatively simple. First, the stirring vane assembly  135 , which is appropriately sized, is slid into the cooking vessel  10 . The stirring vane assembly  135  should fit very closely within the inner diameter of the cooking vessel  10 . Also, the lower thrust surface  149  should glide easily along an upper rim of the opening of the cooking vessel  10 . In addition, the bottom edge surface  174  of the stirring vane  160  should just contact the bottom surface  20  of the cooking vessel  10  without creating any appreciable drag during operation. A large appreciable drag force would prevent the stirring vane from turning easily within the cooking vessel  10 . Also, excess drag along the bottom surface  20  or inner wall surface  18  of the vessel  10  would cause increased wear not only of the vessel  10  but also of the drive assembly  120  and stirring vane assembly  135 . Once the stirring vane assembly  135  is correctly matched and installed within the cooking vessel  10 , the housing  110  and drive assembly  120  are installed onto the handle  12  of the cooking vessel  10 . The housing  110  and drive assembly  120  should be aligned such that the drive gear  128  and the guide lip  114  positively engage the ring gear  140 . Otherwise, the teeth of the drive gear  128  may slip. Once the location of the housing  110  has been adjusted, the threaded knob  112   b  is engaged onto the stem of the housing  110 , and tightened. 
   Once installation is complete, the power source  122  (for example, a battery or an external AC to DC power adapter) is then electrically connected. The cooking vessel  10  with the automatic stirring system  100  installed, is then placed onto a cooking surface where the user may add the food ingredients or mixture to be cooked in a conventional manner. At the user&#39;s discretion, the automatic stirring system  100  may be activated by rotating the speed control knob  116  to achieve a desired stirring speed. From time to time, as more ingredients are added into the cooking vessel  10  or as the quantity or viscosity of the mixture changes, the speed control knob  116  may need to be adjusted to accommodate for the increase or decrease in drag. 
   With reference to  FIGS. 8-9 , a second embodiment of an automatic stirring system  200  is shown. The second embodiment shares many characteristics and structures similar to that of the first embodiment. However, there are two primary distinctions. The first distinction involves the use of a cooking vessel  210  having a first handle  212   a  and a second handle  212   b  mounted 180° apart. Another distinction involves a drive assembly  220  that is integrated with the cooking vessel  210 , specifically, within the first handle  212   a . As with the first embodiment, the second embodiment includes a power source  222 , a motor  224 , a reduction unit or transmission  226 , and an output drive gear  228 . The primary difference between the drive assembly of the first embodiment and the drive assembly  220  of the second embodiment involves the coupling between the motor  224  and the reduction or transmission unit  226 . In particular, the coupling involves a 90° or right angle drive  229 . The right angle drive permits the motor  224  and the transmission  226  to be fitted properly within the first handle  212   a . Naturally, a combined motor and reduction unit having adequate torque capability could be compactly made to fit within the volume generally occupied by the transmission  226  of the second embodiment, thus eliminating the need of the right angle drive  229  altogether. 
   The second embodiment operates in a similar manner as described previously with respect to the first embodiment. A stirring vane assembly  235  is disposed within the cooling vessel  210 . It includes a ring gear  240  and a pair of stirring vanes  260 . As with the first embodiment, the drive gear  228  engages the ring gear  240  to cause the stirring vane assembly  235  to rotate within the cooking vessel  210 . In addition, the stirring vanes  260  include the same forward swept design to promote uniform mixing of the mixture or food ingredients within the cooking vessel  210 . Also, the second embodiment of the automatic stirring system  200  includes an integrated speed control or switching unit  270  within the first handle  212   a . The switching unit  270  may be a simple on/off switch or may be a momentary switch having a speed control circuit allowing the user to toggle among multiple speed settings (such as high, medium and low). In all other respects, the operation of the second embodiment of the automatic stirring system  200  is the same as that of the first embodiment. 
   In another embodiment, the speed control unit of the drive assembly includes a speed sensor such that the output speed of the motor, drive gear or ring gear is monitored. As the load increases, the speed sensor would reflect any changes in the rotational speed of the stirring vane assembly. If the speed sensor indicates a lower speed than what is set, the speed control unit would increase the voltage and/or current supply to the motor thereby creating greater torque to overcome the additional drag of the ingredients in the cooking vessel. 
   In yet another embodiment, the automatic stirring system would include a housing, a stirring vane assembly, and a drive assembly that would be fabricated from a high grade aluminum or stainless steel alloy. In addition, the same housing and drive assembly unit would be designed to accommodate an entire range of cooking vessels. In which case each cooking vessel would use a stirring vane assembly that is appropriately matched for that given cooking vessel. Therefore, a user who owns a range of cooking vessels with varying diameters or capacities need not have a separate housing and drive assembly for each vessel. 
   In still another embodiment, the ring gear is designed to include an additional upper or inner flange to allow the lid of the cooking vessel to sit on top of the ring gear. This would allow the cooking vessel to be capped as if the automatic stirring system were not installed on the cooking vessel. In this embodiment, the lid would simply rotate along with the ring gear and would not inconvenience the user or impact the mixing of the food mixture. 
   Again, it should be noted that the various embodiments of automatic stirring systems disclosed herein provide several distinctions and advantages over the prior art. For example, the user or chef is not obstructed from being able to add or remove ingredients. In other words, the mechanisms that are involved are oriented about a periphery of the cooking vessel such that the user may add or remove the mixture with relative ease and without obstruction of the components of the automatic stirring system. In addition, the swept design of the stirring vanes optimize homogenous mixing. Still further, the drive assembly and housing may be interchanged with various cooking vessels and stirring vane assemblies. 
   Several exemplary embodiments have thus been described. Modifications and alterations may occur to others upon reading and understanding the preceding detailed description. It is intended that the exemplary embodiments be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.