Abstract:
An agitator assembly for use with mixers is provided. This agitator assembly includes an agitator shaft adapted to receive a flow of liquid coolant therethrough; a first hub assembly mounted on the agitator shaft; a second hub assembly mounted on the agitator shaft; at least one agitator bar connecting the first hub extension to the second hub extension, wherein the agitator bar further includes a conduit for delivering liquid coolant from the first hub extension to the second hub extension; and at least one agitator bar connecting the second hub extension to the first hub extension, wherein the agitator bar further includes a conduit for returning liquid coolant from the second hub extension to the first hub extension.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/246,793 filed on Sep. 29, 2009 and entitled “Refrigerated Agitator Assembly for Mixers,” the disclosure of which is hereby incorporated by reference herein in its entirety and made part of the present U.S. utility patent application for all purposes. 
    
    
     BACKGROUND OF THE INVENTION 
     The described invention relates in general to a system and apparatus for mixing viscous substances such as dough, and more specifically to a refrigerated agitator assembly which may be incorporated into industrial horizontal dough mixers for controlling the temperature of the substance being mixed during the mixing process. 
     Friction and viscous shear encountered during mixing typically causes a temperature rise in a substance being mixed. This temperature rise becomes more severe as mixing speed increases and can adversely affect a mixing process by making the substance sticky and difficult to process. Accordingly, mixers, particularly dough mixers, are most effective when equipped with some type of temperature control means, whereby the temperature of the substance to be mixed may be stabilized at a predetermined level or maintained below a predetermined threshold. For example, bread dough should be mixed at a temperature of about 78-80° F. A known means for controlling the temperature of a substance being mixed is through the use of a refrigeration jacket attached to the mixing bowl component of a mixer. Bowl refrigeration jackets, also referred to as “cooling jackets” usually include multiple coolant channels that are arranged perpendicular to the ends of a mixing bowl, and which are arrayed around the profile of the mixing bowl. 
     Large commercial scale dough mixers may be manufactured both with and without mixing bowl cooling jackets based primarily on the type and quantity of dough to be mixed. The performance, i.e., cooling capacity, of a refrigeration system used with a commercial scale mixer is the ability of the mixing bowl cooling jacket to remove heat from within the mixing bowl during a batch cycle. As previously indicated, major sources for heat generated during the mixing process are dough ingredient temperatures, ambient temperatures around the mixer, and heat generated from friction and shearing forces within the mixing bowl as the dough is processed. In some circumstances, these variables make it difficult or impossible for a mixing bowl cooling jacket to provide adequate cooling. 
     U.S. Pat. No. 6,047,558, which is incorporated herein by reference in its entirety for all purposes, teaches the use of a refrigerated agitator assembly as a means for increasing or enhancing the cooling capacity of a refrigeration system incorporated into a mixing apparatus. While effective for its intended purpose, this system is known to experience multiple sources of coolant leaks within the mixer product zone and to possess inefficient internal flow characteristics. Thus, there is an ongoing need in the art of dough mixing for a refrigerated agitator assembly having enhanced coolant sealing, simplified manufacturing, and more efficient cooling characteristics. 
     SUMMARY OF THE INVENTION 
     The following provides a summary of certain exemplary embodiments of the present invention. This summary is not an extensive overview and is not intended to identify key or critical aspects or elements of the present invention or to delineate its scope. 
     In accordance with one aspect of the present invention, an agitator assembly for use with mixers is provided. This agitator assembly includes an agitator shaft adapted to receive a flow of liquid coolant therethrough; a first hub assembly mounted on the agitator shaft; a second hub assembly mounted on the agitator shaft; at least one agitator bar connecting the first hub extension to the second hub extension, wherein the agitator bar further includes a conduit for delivering liquid coolant from the first hub extension to the second hub extension; and at least one agitator bar connecting the second hub extension to the first hub extension, wherein the agitator bar further includes a conduit for returning liquid coolant from the second hub extension to the first hub extension. The first hub assembly further includes a hub adapted to receive a flow of liquid coolant therethrough; and a first hub extension adapted to receive a flow of liquid coolant therethrough, wherein the hub and the first hub extension are in fluid communication with one another and with the agitator shaft. The second hub assembly further includes a hub; and a second hub extension adapted to receive a flow of liquid coolant therethrough. 
     In accordance with another aspect of the present invention, an agitator assembly for use with industrial mixers is provided. This agitator assembly includes an agitator shaft; a first hub assembly mounted on one end of the agitator shaft; a second hub assembly mounted on the opposite end of the agitator shaft; and at least one dual agitator bar assembly. The agitator shaft further includes both a fluid supply passage and a fluid return passage for liquid coolant. The first hub assembly further includes a hub having a set of fluid supply and return passages formed therein, wherein the fluid supply and return passages in the hub are in fluid communication with the fluid supply and return passages in the agitator shaft; and a first hub extension attached to the hub, wherein the first hub extension includes fluid supply and return passages that are in fluid communication with the fluid supply and return passages formed in the hub. The second hub assembly further includes a hub; and a second hub extension attached to the hub, wherein the second hub extension further includes a fluid inlet and a fluid outlet and a transfer duct connecting the fluid inlet to the fluid outlet. The dual agitator bar assembly further includes a first agitator bar, wherein the first agitator bar further includes a conduit for transferring coolant between the fluid supply passage of the first hub extension and fluid inlet of the second hub extension; and a second agitator bar, wherein the second agitator bar further includes a conduit for transferring coolant between the fluid outlet of the second hub extension and the fluid return passage of the first hub extension. 
     In yet another aspect of this invention, an agitator assembly for use with industrial mixers used for bread dough and the like is provided. This agitator assembly includes an agitator shaft; a first hub assembly mounted on one end of the agitator shaft; a second hub assembly mounted on the opposite end of the agitator shaft; a dual agitator bar assembly; a third agitator bar; and a fourth agitator bar. The agitator further includes both a fluid supply passage and a fluid return passage for liquid coolant. The first hub assembly further includes a hub having a first set of fluid supply and return passages formed therein and a second set of fluid supply and return passages formed therein, wherein both sets of fluid supply and return passages in the hub are in fluid communication with the fluid supply and return passages in the agitator shaft; a first hub extension attached to the hub, wherein the first hub extension includes fluid supply and return passages that are in fluid communication with the first set of fluid supply and return passages formed in the hub; and a second hub extension attached to the hub, wherein the second hub extension includes fluid supply and return passages that are in fluid communication with the second set of fluid supply and return passages formed in the hub. The second hub assembly further include a hub; a third hub extension attached to the hub, wherein the third hub extension further includes a fluid inlet and a fluid outlet and a first transfer duct connecting the fluid inlet to the fluid outlet; and a fourth hub extension attached to the hub, wherein the fourth hub extension further includes a fluid inlet and a fluid outlet and a second transfer duct connecting the fluid inlet to the fluid outlet. The dual agitator bar assembly further includes a first agitator bar, wherein the first agitator bar includes a conduit for transferring coolant between the fluid supply passage of the first hub extension and fluid inlet of the third hub extension; and a second agitator bar, wherein the second agitator bar includes a conduit for transferring coolant between the fluid outlet of the third hub extension and the fluid return passage of the first hub extension. The third agitator bar further includes a conduit for transferring coolant between the fluid supply passage of the second hub extension and the fluid inlet of the fourth hub extension. The fourth agitator bar further includes a conduit for transferring coolant between the fluid outlet of the fourth hub extension and fluid return passage of the second hub extension. 
     Additional features and aspects of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the exemplary embodiments. As will be appreciated by the skilled artisan, further embodiments of the invention are possible without departing from the scope and spirit of the invention. Accordingly, the drawings and associated descriptions are to be regarded as illustrative and not restrictive in nature. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated into and form a part of the specification, schematically illustrate one or more exemplary embodiments of the invention and, together with the general description given above and detailed description given below, serve to explain the principles of the invention, and wherein: 
         FIG. 1  is a front perspective view of an exemplary embodiment of an agitator assembly for mixers, in accordance with the present invention; 
         FIG. 2  is a rear perspective view of the agitator assembly of  FIG. 1 ; 
         FIG. 3  is a side view of the agitator assembly of  FIG. 1 ; 
         FIG. 4  is a cross-sectional view of the agitator assembly of  FIG. 1 ; 
         FIG. 5  is a cross-sectional view of the right-hand side of the agitator assembly of  FIG. 1 ; 
         FIG. 6  is an end view of the right-hand side of agitator assembly of  FIG. 1 ; and 
         FIG. 7  is an end view of the left-hand side of agitator assembly of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Exemplary embodiments of the present invention are now described with reference to the Figures. Reference numerals are used throughout the detailed description to refer to the various elements and structures and arrows are used to indicate the direction of coolant flow through the system. Although the following detailed description contains many specifics for the purposes of illustration, a person of ordinary skill in the art will appreciate that many variations and alterations to the following details are within the scope of the invention. Accordingly, the following embodiments of the invention are set forth without any loss of generality to, and without imposing limitations upon, the claimed invention. 
     The present invention relates to a refrigerated agitator assembly for use with mixers. As previously indicated, a first general embodiment of this invention provides an agitator assembly for use with mixers that include a cooling or refrigeration circuit; a second general embodiment of this invention provides an agitator assembly for use with industrial mixers; and a third general embodiment of this invention provides an agitator assembly for use with industrial or commercial mixers used for bread dough and the like. With reference now to the Figures, one or more specific embodiments of this invention shall be described in greater detail.  FIGS. 1-7  provide various views illustrative views of an exemplary embodiment of refrigerated agitator assembly  10 , in accordance with the present invention. As shown in  FIGS. 1-3 , agitator assembly  10  is typically stainless steel or other suitable metal and includes rotary union assembly  100 , agitator shaft assembly  200 , right hub assembly  300 , left hub assembly  400 , double agitator bar assembly  500 , supply (i.e., forward flow) agitator bar  600 , and return (i.e., reverse flow) agitator bar  700 . 
     As best shown in  FIGS. 4-5 , rotary union assembly  100  includes housing  102  that further includes fluid inlet  104  for receiving a supply of liquid coolant or refrigerant (note: these terms are used interchangeably herein) and fluid outlet  106  for removing the liquid coolant or refrigerant from the cooling circuit. A liquid coolant or refrigerant that is compatible with this invention is glycol, although other acceptable coolants or refrigerants may be used. Rotary union body  108  includes conduit  110  running lengthwise therethrough, and stationary coolant feed tube  114 , which is in fluid communication with rotary union fluid inlet  112 , is positioned within conduit  110  such that a portion of the diameter of conduit  110  remains open to accept the flow of coolant leaving the circuit. Bushing  116  is used to seal the connection between stationary coolant feed tube  114  and rotating feed tube  214 . One end of rotary union body  108  is inserted into rotary union adapter  118  and adapter end cap  120  is secured to agitator shaft  202  using connectors  124 .  0 -ring  122  is used to seal the connection between rotary union adapter  118  and agitator shaft  202 . The external diameter of rotary union body  108  is less than the diameter of conduit  204 , which is formed in agitator shaft  202  for allowing coolant leaving the circuit to pass through conduit  204 . Rotary union body  108  includes a plurality of ducts  136  formed therein for allowing coolant leaving the circuit to pass through rotary union body  108  and into conduit  100 . 
     As best shown in  FIGS. 4-5 , rotatable agitator shaft assembly  200  includes dual flow agitator shaft  202 , which further includes variable diameter conduit  204 , which is formed lengthwise through the body of agitator shaft  202 . Coolant supply duct  206  is formed transversely (i.e., perpendicular to conduit  204 ) in agitator shaft  202  and functions as a passage for coolant to leave agitator shaft  202  at two locations. Coolant return duct  208  is formed transversely (i.e., perpendicular to conduit  204 ) in agitator shaft  202  and functions as a passage for coolant to enter agitator shaft  202  and conduit  204  at two locations. In this embodiment, four seal inserts  210  cooperate with a series of o-rings  212  to effectively seal the connections between ducts  206  and  208  and the supply and return ducts formed in hub  302 . Rotating coolant feed tube  214  is positioned within conduit  204  and the external diameter of this tube is less than the diameter of conduit  204  for allowing coolant leaving the circuit to pass through conduit  204 . Conduit  216  is formed though the length of rotating coolant feed tube  214  for supplying coolant to supply duct  206  through tip or terminus  218 . 
     As best shown in  FIG. 5 , right hub assembly  300  (which may also be referred to as a “spider” or a “spider hub”) includes right hub  302 , which is mounted on agitator shaft  202 . Right hub  302  includes supply duct  304  for supplying coolant to first hub extension  312  and return duct  306  for receiving coolant from first hub extension  312 . Right hub  302  also includes supply duct  308  for supplying coolant to second hub extension  320  and return duct  310  for receiving coolant from second hub extension  320 . As best shown in  FIGS. 5-6 , first hub extension  312  is attached to right hub  302  and includes supply duct  314  for supplying coolant to double agitator bar assembly  500  and return duct  316  for receiving coolant from double agitator bar assembly  500 . Ducts  314  and  316  are typically machined into the metal of first hub extension  312  and then enclosed within first hub extension  312  by welding cover plates  318  and  319  (see  FIG. 6 ) over these ducts. Second hub extension  320  is also attached to right hub  302  and includes supply duct  322  for supplying coolant to supply (i.e., forward flow) agitator bar  600  and return duct  324  for receiving coolant from return (i.e., reverse flow) agitator bar  700 . Ducts  322  and  324  are typically machined into the metal of second hub extension  320  and then enclosed within second hub extension  320  by welding cover plates  326  and  328  (see  FIG. 6 ) over these ducts. 
     As best shown in  FIGS. 4 and 7 , left hub assembly  400  includes left hub  402 , to which third hub extension  404  and fourth hub extension  408  are attached. In this embodiment, no fluid passages, ducts, or conduits are formed in either hub  402  or the end of agitator shaft  202  upon which hub  402  is mounted. Third hub extension  404  includes transfer duct  406  (a “bottom to top” transfer duct) that transfers coolant from supply agitator bar  502  to return agitator bar  508 . Fourth hub extension  408  includes transfer duct  410  (a “side to side” transfer duct) that transfers coolant from supply agitator bar  600  to return agitator bar  700 . Ducts  406  and  410  are typically machined into the metal of third hub extension  404  and fourth hub extension  408  and then enclosed within these hub extension by welding cover plates  412  and  414  (see  FIG. 7 ) over the ducts. 
     As best shown in  FIGS. 4-5 , double agitator bar assembly  500  includes two agitator bars having different external and internal diameters that connect first hub extension  312  to third hub extension  404 . Supply agitator bar  502  is the smaller of the two agitator bars and includes conduit  504 , which is formed lengthwise through agitator bar  502  for supplying coolant to return agitator bar  508 . In this embodiment, baffle  506  is positioned within conduit  504  to induce turbulence in coolant flowing through agitator bar  502  and to provide increased structural support for preventing possible collapse of the exterior of the agitator bar during the mixing process. Return agitator bar  508  includes conduit  510  which is formed lengthwise through agitator bar  508  for returning coolant from third hub extension  404  to first hub extension  312 . Baffle  512  is positioned within conduit  510  to induce turbulence in coolant flowing through agitator bar  508  and to provide increased structural support for preventing possible collapse of the exterior of the agitator bar during the mixing process. Supply agitator bar  600  includes conduit  602 , which is formed lengthwise through agitator bar  600  for supplying coolant from second hub extension  320  to fourth hub extension  408 . Return agitator bar  700  includes conduit  702 , which is formed lengthwise through agitator bar  700  for returning coolant from fourth hub extension  408  to second hub extension  320 . Agitator bars  600  and  700  further include internal baffles  604  and  704  for inducing coolant turbulence and for providing structural support during the mixing process. Agitator bar  600 , conduit  602  and baffle  604  may be the same structure as bar  700 , conduit  702  and baffle  704 , as detailed in  FIG. 4 . 
     As shown in  FIGS. 4-7 , the present invention also includes a plurality of mechanical fasteners  50 , which include bolts that are used to squeeze or compress the hub extensions together placing the agitator bars and, therefore, the weld joints under a predetermined amount of compression. Based on any temperature difference the agitator assembly may experience due to repeated thermal expansion and contraction, the agitator bars are unlikely to expand to the point where the weld joint experiences a tensile force. This construction reduces the likelihood of stress cracks developing in the welds where the agitator bars are welded to the hub extensions and substantially increases the durability and longevity of agitator assembly  10 . 
     Advantageously, the present invention may be more easily manufactured than known refrigerated agitators and is therefore less expensive to produce. For example, the parallel flow of coolant allows for reduced machining by utilizing the agitator bars as return channels. This invention also includes a limited number of coolant fluid couplings or joints inside the mixing bowl or product zone. The exemplary embodiment shown in the Figures includes only two fluid passages within mixing bowl and only four sealing joints. The present invention provides an increase in the convective cooling characteristics of a refrigerated agitator assembly through the use of turbulence enhancement in the internal coolant flow of the agitator bars. 
     While the present invention has been illustrated by the description of exemplary embodiments thereof, and while the embodiments have been described in certain detail, it is not the intention of the Applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention in its broader aspects is not limited to any of the specific details, representative devices and methods, and/or illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the applicant&#39;s general inventive concept.