Abstract:
Disclosures of roller tube grill temperature control assemblies and methods for human food have a sensing device to fit between a pair of tubes with sides that conform to the tube surface, and an associated temperature-sensing component for detecting the sensing device temperature. An electrical control arrangement in electrical connection with a heating element disposed within a tube can control electricity, with mechanisms to modify the set point. A biasing member biases the sensing device. Such device can also have on or more tube receiving inner openings located between the sides of the device. The sensing device can further be a bushing with one or more generally cylindrical openings to receive roller tube or tubes. The assembly moreover can have an infrared sensing device associated with a tube to sense radiation therefrom for detecting temperature.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Patent Application No. 61/843,215, filed on Jul. 5, 2013 with named inventors Michael L. Huegerich and James G. Luntz, the disclosure of which is incorporated herein by reference in its entirety. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     Roller grill assemblies for cooking human food, such as disclosed in U.S. Pat. No. 6,393,971, have a group of heated rollers upon which food such as hot dogs, wieners, bratwurst, sausage, ground meat and the like can be cooked. Drawings from U.S. Pat. No. 6,393,971 are shown in  FIGS. 1 and 2  hereof. Preferably temperatures of 140° F. are required for sanitation for the center of the product cooked upon the roller tubes. 
     The setting required to obtain the temperature of 140° F. for the center of product varies, for example, because of variance in product size, the constituency of the product, and whether there is a cover over the product, such as a sneeze guard. Control systems for controlling the temperature of tubes in roller grills have been employed, such as shown in U.S. Pat. No. 6,707,015 B2. U.S. Pat. No. 6,707,015, a drawing of which is shown in  FIG. 3  hereof, discloses the use of sensors, such as thermistors encased in stainless steel, located between the ends of a pair of rollers and spaced therefrom. 
       FIG. 4  shows a prior art arrangement wherein a sensing device in the form of a thermistor within a steel jacket  20  is located to be spaced from the interior surface  22  of a roller tube  24 , and spaced from a heating element  26 . The thermistor  20  is thus surrounded by air.  FIG. 4  also shows supporting brackets  28  and  30  for the heating element  26 . A sealing bearing  32  is mounted to a housing wall  34 , and about tube  24 , with an O-ring  36  within an annular groove of bearing  32 . Another O-ring  38  is to the interior of bearing  32 . 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       Illustrative embodiments are shown in the drawings which form a part of the specification. 
         FIG. 1  is an isometric view of a prior art roller grill assembly similar to that shown in FIG. 1 of U.S. Pat. No. 6,393,971 B1; 
         FIG. 2  is a side elevation of the prior art roller grill of  FIG. 1 , with the sneeze-guard cover removed, and with the right side of the wall disassembled and removed, similar to that of FIG. 7 of U.S. Pat. No. 6,393,971 B1; 
         FIG. 3  is a side elevation of a prior art roller grill assembly such as disclosed in U.S. Pat. No. 6,707,015 B2, similar to the view of the roller grill assembly shown in FIG. 2 of that Patent; 
         FIG. 4  is a section view of a prior art roller grill assembly showing a thermistor used as a temperature sensor and located inside the roller tube spaced from the inner surface of the roller tube and spaced from the heating element inside the roller tube; 
         FIG. 5  is an isometric view of a first embodiment of a sensing device that is positioned to be in contact with the outer surfaces of roller tubes; 
         FIG. 6  is a rear elevation of the sensing device of  FIG. 5 ; 
         FIG. 7  is a top plan view of the sensing device of  FIG. 5 ; 
         FIG. 8  is a bottom plan view of the sensing device of  FIG. 5 ; 
         FIG. 9  is a partial side elevation of part of the roller grill assembly, showing two sensing devices of  FIGS. 5-8 , each mounted between a pair of roller tubes with sensing device surfaces in contact with the roller tubes, and with a hold-down spring shown mounted in connection with the sensing device shown to the right; 
         FIG. 10  is a section view taken on the line  10 - 10  of  FIG. 9 , showing the sensing device in contact with the outer surface of a roller tube, and showing the position of the heating element, supporting brackets and sealing components; 
         FIG. 11  is a section view taken on the line  11 - 11  of  FIG. 9 , showing the sensing device mounted about the exterior surface of a roller tube, and further showing a bore in the sensing device that houses a thermistor for sensing temperature; 
         FIG. 12  is a side elevation of a second embodiment of a sensing device, which has surfaces that allow contact of the device with the surfaces of four separate roller tubes; 
         FIG. 13  is an isometric view of a third embodiment of a sensing device, illustrating a sensing device and bushing combination that fits about a roller tube to be in contact with the roller tube for thermal conduction; 
         FIG. 14  is a top plan view of the sensing/bushing device of  FIG. 13 ; 
         FIG. 15  is an elevation showing a sensing/bushing device of  FIGS. 13 and 14  mounted about a roller tube to be in contact with the roller tube for thermal conduction; 
         FIG. 16  is an isometric view of a fourth embodiment of a sensing device showing a sensing/bushing device for mounting about a pair of roller tubes; 
         FIG. 17  is a top plan view of the sensing/bushing device of  FIG. 16 ; 
         FIG. 18  is a side elevation of the sensing/bushing of  FIGS. 16 and 17  mounted about a pair of roller tubes to be in contact with the roller tubes for thermal conduction; 
         FIG. 19  is an isometric view illustrating a temperature sensing device in an arrangement for infrared temperature sensing; 
         FIG. 20  is a schematic view of an electronic control system for temperature sensing devices such as disclosed herein; 
         FIG. 21  is an isometric view of the embodiment of  FIG. 12 ; and 
         FIG. 22  is a front elevation of the sensing device of  FIG. 21 . 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION OF INVENTION 
     The following detailed description illustrates the invention by way of example and not by way of limitation. This description will clearly enable one skilled in the art to make and use the invention, and describes several embodiments, adaptations, variations, alternatives and uses of the invention, including what I presently believe is the best mode of carrying out the invention. As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. 
     The temperature control assemblies disclosed herein are part of an integrated system for use in conjunction with roller grills. Typically roller grills have a group of heated roller tubes upon which food such as hot dogs, wieners, bratwurst, sausage, ground meat and the like can be cooked. Examples of such roller grills are shown and disclosed in U.S. Pat. No. 6,393,971 B1 and U.S. Pat. No. 6,707,015 B2, both of which patents are incorporated herein by reference as if fully set forth herein. 
       FIGS. 1 and 2  hereof are taken from U.S. Pat. No. 6,393,971 B1, while  FIG. 3  shows a drawing from U.S. Pat. No. 6,707,015 B2. With regard to  FIGS. 1 and 2 , the roller grill assembly  50  primarily comprises a main housing  54  upon which are mounted a plurality of rotatable cooking tubes  56  with interior tube heating members  58 . The roller assembly  50  further comprises sealing subassemblies  60 , and a sneeze guard cover  62 . Assembly  50  further comprises a drive assembly disclosed in U.S. Pat. No. 6,393,971 B1. 
       FIG. 3  has similar components.  FIG. 3  also shows prior art sensors  66  located at the end of, and in between, pairs of roller tubes  68 . 
     Referring to  FIGS. 5-8 , which show isolated views of a sensing device  70 , device  70  generally has a “T”-shape with arcuate sides about its midsection. More specifically, sensing device  70  has a generally flat bottom side  74  whose width can vary, but in one embodiment is about 0.867 in. wide. From its bottom  74 , at each of its edges the device  70  extends upwardly into generally vertical lower sidewalls  77  and  80 , whose height can vary, but in one embodiment are each about 0.093 inches tall. The tops of each of lower sidewalls  77  and  80  extend into a pair of arcuate sidewalls  83  and  86 , respectively, whose dimensions are configured to extend adjacent the exterior contour of a roller tube it faces. In one embodiment, the radius for the sidewalls  83  and  86  is about 0.537 in. The radius is dependent upon the diameter of the roller tubes that sensor  70  abuts. At the upper end of each arcuate sidewall  83  and  86 , device  70  has a generally vertical upper sidewall  89  and  92 , respectively, whose length can vary but in one embodiment is about 0.175 in. 
     At the top of device  70 , the device  70  has a generally flat upper surface  95 . The device has a generally “T”-shaped outer surface  98 , and a generally “T”-shaped inner surface  100 . The sensor&#39;s thickness can vary. In one embodiment it is about 0.200 in. thick. The width of the upper surface  95  can vary. In an embodiment it is about 1.700 in. 
     At the device&#39;s upper surface  95 , a generally cylindrical bore  103  has an upper opening  106 , and extends downwardly with its lower end  109  being closed. Bore  103  receives a thermistor to be described. The diameter of bore  103  can vary, but in one embodiment it has a diameter of about 0.129 in. Toward the lower end of the device  70 , a transverse bore  112  extends from the outer surface  98  through the inner surface  100  of the device  70 . The transverse bore  112  receives the upper end of a hold-down spring to be described. The diameter of transverse bore  112  can vary, and its size can be dependent upon the diameter of the end of the end of the hold down spring inserted therein. In an embodiment, the diameter of bore  112  is about 0.093 in. 
     Sensor  70  can be of metal or other suitable material for conducting heat. 7075 Aluminum and 6013 Aluminum are suitable substances for the composition of sensing device  70 . 
       FIG. 9  shows a view of two devices  70  each associated with a pair of roller tubes  114  on a roller grill. The surface of the roller tubes  114  can comprise a layer of an appropriate PTFE (polymer of tetrafluoroethylene) material on a steel tube. As seen in  FIGS. 9-11 , the device  70  can be mounted in the assembly to contact the outer surfaces of two of the roller tubes  114 . In  FIG. 9 , upper sidewall  92  of sensing device  70  is shown extending slightly beyond the centerline of the tube  114  upon which centerline the section view of  FIG. 10  is taken. 
     In  FIG. 9  the device  70  shown to the right has a hold-down spring  115  secured to it, and the device  70  to the left of  FIG. 8  does not have a hold-down spring shown. With regard to  FIG. 9 , the arcuate side surfaces  83  and  86  of device  70  generally fit flush against the conforming outer arcuate surface of the roller tube  114  which it faces. This allows heat to flow by conduction from the outer surface of each of said tubes  114  to the device  70 . 
     Turning to  FIGS. 10-11 , there is illustrated a sensing device  70  mounted to be in contact with the outer surface of a roller tube  114 . The housing wall  116  has a cylindrical bore  119  which receives an annular-shaped bearing  122 . Bearing  122  can be of synthetic material such as plastic. Bearing  122  has an annular groove  125  which receives the adjacent housing wall  116  structure about the bore  119 . The bearing  122  has an outer facing annular surface  130  that is generally flat, and which abuts the inner surface  100  of sensing device  70 , as shown in  FIGS. 10 and 11 . Bearing  122  has a bore  133  within which is formed an annular recess  136  which receives an O-ring  139 . The surface of bearing bore  133  receives the outer surface of roller tube  114  for rotation therein. An O-ring  140  extends about roller tube  114  to the inside of bearing  122 . 
     As shown in  FIGS. 10 and 11 , a tubular heating member  144  shown as a rod, extends through roller tube  114 . The end of heating rod  144  has a terminal  147  that is secured to an angled link  150  that connects to wiring. Further, as shown in  FIGS. 10 and 11 , a lower mount plate  153  is secured to housing wall  116  as by nuts and bolts. A lower tube support bracket  157  has its lower flanged section  159  secured to housing wall  116  as by nuts and bolts. Bracket  157  has a channel shaped section  162  which has an inner wall  165  that has an end  168  that bends upwardly to support heating rod  144 . Above heating rod  144  an upper heating member support bracket  169  has its upper-flanged end  171  secured to the housing wall  116  as by nuts and bolts. Bracket  169  likewise has a channel-shaped section  174  with its lower flange  176  extending alongside, and in contact with, the surface of heating rod  144 , so that it and the lower bracket  157  provide upper and lower stability and support for the heating rod  144 . 
     With more specific reference to  FIG. 11 , a thermistor  178  is shown inserted within the sensing device bore  103 . A pair of wires  180  extends from the thermistor  178  to provide feedback from the thermistor  178  as to temperature, so that a temperature probe is provided within sensing device  70 . The thermistor  178  can be located within a steel jacket as shown in  FIG. 11 , and thus removable from the bore  103 . A thermistor can also be potted directly within bore  103 . 
     The support/stability brackets  157  and  168  help to shield the sensing devices  70  from ambient temperatures so that the sensing devices  70  react more closely to the temperature of the roller tubes only. 
     The spring  115  is shown as a helical coil spring which has a general straight horizontally extending upper end  157  that is snugly received with bore  112  at the lower end of device  70 . The lower end of spring  115  can be looped to fit about, and be held by, a pin  184  that is mounted to housing wall  116  as by a weld, screw or nut. The lower end of spring  115  can be held to other parts of the roller grill structure as well. The spring  115  provides a gentle downward force against sensing device  70  to provide better contact of the arcuate surfaces  83  and  86  of device  70  with the surface of the roller tubes  114  that that device  70  abuts. 
     An electronic control  182  is electrically connected to the thermistors  178  and the heating elements  26  in order to sense the temperature of the rollers tubes  24  and, in response to the sensed temperature, control an electrical current provided to the heating elements  26 . The control  182  operates by energizing a relay  184  that provides current to the heating elements  26  until a target temperature is reached. When the target temperature is reached, as determined by sensing an output from one of the thermistors  178 , the control  182  de-energizes the relay  184  to stop electrical current to a set of heating elements  26 . The control may optionally further include a timer function that prevents the relay  184  and thus the heating elements  26  from being cycled too quickly between the on and off state. 
     Referring to  FIG. 20 , the control  182  is further electrically connected to a display  186  and keypad  188 . Using the keypad  188 , a user can increase or decrease a set-point temperature for the control  182  to heat the roller tube  24 . The keypad  188  can further include dedicated keys  190  indicating a certain type of food (for example, “hot dogs” or “breaded product”) to auto-set the control  182  to a predetermined temperature set-points stored within the control  182  appropriate for that food product and roller grill model (for example, “with sneeze guard” and “without sneeze guard”. 
     A second embodiment of the disclosure is shown in  FIG. 12 . A sensing device  70 ′ is configured to fit about four roller tubes  114 ′. The outer ends of device  70 ′ have lower and upper sidewalls  77 ′,  80 ′,  89 ′ and  92 ′, and arcuate sidewalls  83 ′ and  86 ′, that are configured and dimensioned as described for the embodiment of device  70  shown and described for  FIGS. 5-9 . In  FIG. 12 , device  70 ′ is shown with its arcuate sidewalls  83 ′ and  86 ′ abutting the circular surfaces of their corresponding roller tubes  114   a  and  114   b , so that those tubes can rotate and remain in heat conductive contact with surfaces  83 ′ and  86 ′. In addition, sensing device  70 ′ has two inner openings  200  and  202  that have arcuate inner walls  206  and  208 . The radius of inner walls  206  and  208  is the same as that for arcuate sidewalls  83  and  86  of  FIGS. 5-9 . Like device  70 , the arcuate wall radius of device  70 ′ depends on the diameter of the roller tubes that it abuts. 
     However, the length of each of arcuate walls  206  and  208  is about twice as long as that of sidewalls  83  and  86 , respectively, The lower ends of arcuate walls  206  and  208  terminate into vertical lower sidewalls  210  and  212  respectively. The heights of the lower sidewalls  210  and  212  are the same as that of sidewalls  77  and  80  of the  FIG. 5-9  embodiment. Device  70 ′ has three transverse bores  112 ′ for receiving the upper end of springs such as spring  115  of the  FIGS. 5-9  embodiment. Device  70 ′ has three vertical bores  103 ′ like that of bore  103  of  FIGS. 5-9 , which receive thermistors having wires  180 ′. Device  70 ′ thus provides for temperature readings that are based on heat conducted from four roller tubes, and thus with a single sensing device gives a greater sourcing for overall reading of temperature than does the embodiment of  FIGS. 5-9 . If desired, another thermistor could be placed in a bore located at the center of the top of device  70 ′. 
     Thus it can be seen that with the embodiments of  FIGS. 5-12 , temperature feedback is received from two or more rollers to the respective sensing device. This provides more accurate and consistent reading of the temperature of the actual roller tubes that are conveying heat directly to the foods being cooked thereon. 
     A third embodiment of the disclosure is shown in  FIGS. 13-15 . This embodiment combines heat sink and sensing features with bushing or bearing features. As seen in  FIGS. 13-15 , the sensor/bushing device  300  has a cylindrical section  302  with ring lands  305  for receiving parts of a snap ring and inner cover (not shown) to hide and seal the sensor/bushing device  300 . Cylindrical section  302  has a bore  308  with an inner cylindrical surface  311 . Surface  311  has a diameter configured to receive a roller tube  114 ″ for smooth rotation therein, as shown in  FIG. 15 , but sufficient to allow conductive transfer of heat from the roller tube  114 ″ surface to the sensor/bushing device  300 . A flange  315  of a partial circular shape extends outwardly from the proximal end of cylindrical section  302 . 
     Sensor/bushing  300  has a temperature sensing receiving section  320 , which has somewhat of a rectangular prism configuration, with a generally flat vertical sidewall  323  and a generally flat horizontal top wall  326 . Top wall  326  has a downwardly extending bore  329  extending there through. Bore  329  preferably has a closed lower end and can be of the same configuration as described for bore  103  in the embodiment of  FIGS. 5-9 . As with the embodiment of  FIGS. 5-9 , bore  329  can receive a temperature probe in the form of a thermistor in a steel jacket, such as illustrated in  FIG. 11 . As seen in  FIG. 15 , wires  180 ″ extend to the thermistor seated within bore  329 . 
     The sensor/bushing flanged section  315  has towards its lower end a preferably generally vertical notch  332 . Notch  332  is configured to receive a projection or tab extending from the housing wall  116 ″ to hold the sensor/bushing device  300  against rotation relative to the housing wall  116 ″ that could occur from the rotational frictional force exerted by roller tube  114 ″. 
     The sensor/bushing device can be of suitable material including metal, such as SAE  660  bronze, for example. The sensor/bushing device can also be impregnated with other materials for anti-wear, anti-squeak, and improved thermal conductivity. 
     A fourth embodiment of the disclosure is shown in  FIGS. 16-18 . Like the third embodiment this embodiment combines heat sink and sensing features with bushing or bearing features. As seen in  FIGS. 16-18  a sensor/bushing device  400  has two cylindrical sections  402  and  404 , each having exterior ring lands  305  for snap ring and inner cover (not shown) to hide and seal the device  400 , threads (annular projecting rims)  408  and  411 , respectively. Each of the cylindrical sections  402  and  404  has a bore  414  and  417 , respectively, each of which has a cylindrical surface  420  and  423 , respectively. Each of the cylindrical surfaces  420  and  423  have a diameter configured to receive a roller tube  114 ′″ for smooth rotation therein, as shown in  FIG. 18 , but sufficient to allow conductive transfer of heat from the roller tube  114 ′″ to the surface of the sensor/bushing device  400 . Flanges  428  and  431 , each of a partial circular shape, extend outwardly from the proximal ends of the cylindrical sections  402  and  404 , respectively. 
     Sensor/bushing  400  has a temperature sensing receiving section  435  which has a generally flat upper surface  438  from which downwardly extends a closed-end bore  441 . The distal side  444  of section  435  is generally flat. The lower wall  447  of section  435  is generally flat. Bore  441  can be of the same configuration as described for bore  329  in the embodiment of  FIGS. 13-15 , and for bore  103  in the embodiment of  FIGS. 5-9 . As with those embodiments, bore  441  can receive a temperature probe in the form of a thermistor in a steel jacket, such as illustrated in  FIG. 11 . As seen in  FIG. 18 , wires  180 ′″ extend to the thermistor seated within bore  441 . 
     The outer-flanged sections  428  and  431  each have towards their lower ends preferably generally vertical notch  450  and  452 , respectively. Notches  450  and  452  each are configured to receive a projection or tab extending from the housing wall  116 ′″ to hold the sensor/bushing device  400  against rotation relative to the housing wall. Sensor/bushing device  400  can have the same composition as described for device  300 . 
     A fifth embodiment of the disclosure is shown is  FIG. 19 .  FIG. 19  discloses an infrared sensing device  500  connected to wiring  503 .  FIG. 19  shows a housing wall  116 ″″ which supports a bearing  506  within which a roller tube  114 ″″ rotates. The bearing outer flange can have a notch which receives a projecting tab  510  from wall  116 ″″, to resist rotation of the bearing  506 . A heating element  144 ″″ extends through the roller tube  114 ″″ and has a terminal extension  147 ″″ to which a connecting link  150 ″″ is joined. The sensor  500  can be supported by a sheet metal bracket extending from the housing wall  116 ″″. 
     The lower end of the sensor  515  is preferably between about ½ in. to about ¾ in. from the top surface of the roller tube  114 ″″ as the roller tube  114 ″″ rotates. The infrared sensor can be a commercially available type such as offered through www.omega.com by OMEGA Engineering Inc., telephone No. 888-826-6342 United States. They include models with built-in air purge, which are preferred, such as OMEGA models OS36-2 and OS36-5. Also suitable are those such as sold as Model No. OS365M-K. Additional suitable infrared sensors include recalibrated models such as Models IRt/c.5 and IRt/c.10, of Exergen Corporation, 51 Water Street, Watertown, Mass. 02172, having air purge features. It is preferable to use an infrared sensing device that maintains its ability of measuring and maintaining calibration under operating conditions over a long period of time. 
     In view of the above, it will be seen that advantages of the present invention have been achieved and other advantageous results have been obtained.