Abstract:
A rotary union for supplying a heat exchange fluid to a rotating body includes a pair of hydrodynamic bushing bearings to retain the union housing within the desired alignment with the rotating body, a thrust bearing assembly secured to the rotating body, and a seal assembly positioned forwardly of the pair of bushing bearings. The hydrodynamic bushing bearings are located within the union and are lubricated by the flow of the heat exchange fluid within the union.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is related to and claims the benefit of U.S. Provisional Application Ser. No. 60/610,119 filed Sep. 14, 2004, the teachings of which are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a rotary union having bushing bearings therein and which are positioned within the flow of the heat exchange fluid from the non-rotating body to a rotating member. 
     BACKGROUND OF THE INVENTION 
     A plurality of rotary union structures exist for supplying a heat exchange fluid, such as oil, to a rotating body or load. In the past, one type of self-supported rotating union includes a pair of carbon graphite bearing structures which support and retain the alignment of the rotary union housing with respect to the rotating a rotor or shaft and wherein the rotor or shaft member encircles a siphon pipe through which the hot oil is removed from the interior of a rotating body or load. Such rotating unions may include a pair of carbon graphite bushing bearings and a seal assembly which also acts as a thrust bearing assembly to absorb the thrust forces generated by fluid pressure within the union. The rotary housing is mounted and aligned with respect to the rotating rotor or shaft by the pair of carbon graphite bushing bearings to maintain the housing and the rotor in alignment during operation. However, the front graphite bushing bearings are not in contact with the pumped fluid and, accordingly, such rotary unions have a limited operational temperature of a maximum of about 450° F. and approximately 200 RPMs. 
     Another attempt to provide a self-supported rotary union for communicating a heat exchange fluid to a rotating drum is a rotary union that includes anti-friction rotating bearings located within bearing housings which provide support for the rotary union&#39;s housing with respect to the rotating load. When such roller bearing structures are utilized to support and align the rotary housing in a union supplying hot oil to a load, it has been found that the roller bearing structures are generally operable to a maximum operating temperature of 300° F. Thus, such roller bearing structures require auxiliary lubricating and cooling systems to supply a lubricating oil or a high temperature lubricating grease to the bearing assembly. Accordingly, such complicated rotary unions require expensive high temperature lubricating greases and also result in a change in physical property and performance according to the temperature of the union. Therefore, such union structures are expensive to manufacture and possess a shortened service life. 
     SUMMARY OF THE INVENTION 
     It is one object of the present invention to provide a rotary union for supplying a heat exchange fluid to a rotating body or load which utilizes hydrodynamic bushing bearings to retain the rotary union housing within the desired alignment with respect to the rotating body or load. 
     It is a further object of the present invention to provide a rotary union for delivering a heat exchange fluid to a rotating body or load wherein the rotary union housing is retained in alignment with respect to the rotating body by bushing bearings engaging the rotating body or load. 
     It is yet another object of the present invention to provide a rotary union wherein a pair of bushing bearings are utilized to support the rotary union with respect to a rotating load and wherein the bushing bearings are lubricated by the fluid flow within the union. 
     The present invention provides a novel rotary union for supplying a hot oil to a rotating rotor or load which includes a rear bushing bearing assembly and a front bushing bearing assembly which provide the support for the union housing with respect to the rotating load. The rear or first bushing bearing assembly includes a bearing sleeve mounted for rotation with the rotor and a bearing housing member having an outer radial curved surface mounted within a bore of the cylindrical housing of the rotary union. The bearing housing member includes a graphite wearing portion for engagement with the bearing sleeve member to retain the housing within the desired alignment with respect to the rotating load. The front or second bushing bearing assembly includes a bushing sleeve mounted for rotation with the rotor and also includes a bearing housing member having an outer radial curved surface and includes a graphite wearing portion for structurally receiving and engaging a bearing sleeve mounted to the rotor. In each of the rear and front bushing bearing assemblies, the bearing housing member includes an outer curved radial surface that is structurally arranged to engage the inside surface or bore of the cylindrical housing member to properly align the graphite-wearing portions of both bushing bearing assemblies with the bearing sleeves mounted to the rotor. 
     The self-supported rotary union further includes a thrust bearing assembly comprised of a metallic thrust plate member that is mounted to the rotor for rotation thereby, a carbon graphite spherical ring member and a metallic ring having a spherical contact surface. The spherical contact surface of the metallic ring presents a mating face with the spherical counterface of the carbon graphite ring to absorb the mechanical load from the metallic thrust plate member. 
     Additionally, the rotating union includes a front seal assembly which is comprised of a rotating seal face member fixed to the rotor shaft and a floating seal face member that is spring biased and mounted to the union housing. The front seal assembly is positioned within the rotary union outside of the front bushing assembly. Engagement of the seal facings of the floating and the rotating seal faces occurs when hot oil is passed through the union to contact the front seal assembly which retains the fluid flow within the union. 
     By positioning the front floating seal assembly outside the front bushing bearing assembly, both the rear bushing bearing assembly and the front bushing bearing assembly are located within the fluid flow of the rotating union. Accordingly, this structure, when coupled with the hydrodynamic bearing system which includes sleeve bearings and a thrust bearing, eliminates the need for external lubrication of the bushing bearing assemblies with expensive, high temperature grease or lubricants. Additionally, there is substantially no change in physical properties of the bushing bearing assemblies with the temperature changes required of the pumped fluid within the union. Accordingly, a rotary union in accordance with the present invention is structurally arranged to operate within the range of up to 600° F. and up to 1,000 RPMs. 
     The present invention consists of certain novel features and structural details hereinafter fully described, illustrated in the accompanying drawings, and particularly pointed out in the appended claims, it being understood that various changes in the details may be made from the spirit, or sacrificing any of the advantages of the present invention. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       For the purpose of understanding the present invention, there is illustrated in the accompanying drawings a preferred embodiment thereof, from an inspection of which, when considered in connection with the following description, the invention, its construction and operation, and many of its advantages will be readily understood and appreciated. 
         FIG. 1  illustrates a self-supported rotating union including a pair of carbon graphite bearing structures for mounting and supporting the rotation of a rotor in accordance with the prior art; 
         FIG. 2  illustrates a self-supported rotating union which includes a pair of roller bearing structures for mounting and supporting the rotation of a rotor or shaft in accordance with the prior art; 
         FIG. 3  illustrates a self-supported rotating union incorporating the hydrodynamic bearing system which includes a pair of bushing bearings for mounting and supporting the union housing on the rotor in accordance with the present invention; and 
         FIG. 4  is an enlarged view showing the relationship between the bearing housing member and the inner surface or bore of the rotary union housing in accordance with the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1 , which is labeled “Prior Art”, illustrates a rotating union  10  which may be, for example, a rotary union of the Model H Series, commercially available from the Deublin Company, Waukegan, Ill. Referring now to drawings wherein like numerals have been used throughout the several views to designate the same or similar parts, a rotating union or joint  10  is designed for delivering hot oil or steam to applications in the paper, plastic and textile industries. The rotating union  10  includes a cylindrical housing  11 , a head or end cap  12  and a tubular rotor  13 . The union housing  11  is mounted on the rotor  13  by a rear support carbon graphite bearing  14  and a front support carbon graphite bearing  15 . The heated oil enters into the rotary joint or union  10  through port  16 , and a siphon pipe  17  is enclosed within the rotor  13  and communicates with the head or end cap  12 . When the hot oil enters the rotary union, the oil passes along the siphon pipe  17  into a rotating drum (not shown). The return of the hot oil is through the siphon pipe and out the head  12  of the union  10 . 
     The rotary union assembly  10  includes a seal assembly which includes a thrust plate  18  mounted to the rotor  13 . The thrust plate is in contact with a spherical carbon ring member  19 , which in turn is in contact with a spherical seal face member  20 . The spherical seal face member is keyed to a supporting flange  22  that is secured to the housing  11 . The junction between the carbon ring member  19  and the seal face member  20  provides a structure which absorbs the axial mechanical load from the thrust plate  18  and provides a sealing function for the union. 
     A supporting flange  22  associated with the housing  11  includes an annular recess  23  therein which is structurally arranged to receive the front support carbon graphite bearing  15  to provide support for the rotary union&#39;s housing. Positioned adjacent the rear support carbon graphite bearing  14  is a spring  24  biased counterface member  25  which provides a thrust bearing assembly  26  for the union. The hot oil rotating joint, illustrated in  FIG. 1 , operates generally at 90 psi and at temperatures of 600° F. and at a speed of up to about 350 RPMs. 
       FIG. 2 , which is also labeled “Prior Art” illustrates a rotating union  10  which may be, for example, a rotary union of the Model CK Series, commercially available from the Deublin Company, Waukegan, Ill. The rotating union  10  is designed for delivering hot oil to a rotating load member and includes a cylindrical housing  11 , a head or end cap  12 , a rotor or load  13  and a siphon pipe  17  located within the rotor. The hot oil is directed into the rotary union  10  through inlet port  16 . Specifically, in  FIG. 2  the rotating union  10  includes a rear support roller bearing assembly  14  and a front support roller bearing assembly  15  for supporting the rotary housing  11  with respect to the rotor or load  13 . The outer annular race members  14   a  and  15   a  of the roller bearing assemblies  14  and  15 , respectively, are positioned between a counter bore in the head  12  and in the housing  11 , respectively. Positioned between the rear and front roller bearing assemblies is a rotating sealing member  27  and a floating sealing member  28 , which is spring biased to engage the rotating sealing member  27  to provide a seal during operation of the rotary union. 
     Similarly, the rear roller bearing assembly  14  is isolated from the flow of oil through the union because of the existence of a rear sealing assembly  56 . This assembly includes a rotating seal face member  57  keyed to the rotor and a floating seal face member  58  which provides a seal during operation of the rotary union. 
     The utilization of roller bearing assemblies  14  and  15  within the rotary union  10  requires expensive lubricants to be directed into the roller bearings assemblies through grease nipples  29  to cool the units and to lubricate the same. Thus, such complex and expensive union structures, as shown in  FIG. 2 , necessarily require the use of expensive high-temperature greases and lubricants and oftentimes result in a change of physical properties of the union bearing assemblies depending upon the temperature of the operating unit. Accordingly, such expensive unions generally operate at a pressure of 90 psi, at a temperature of 450° F. and at a speed of 850 RPMs. 
     The novel rotary union in accordance with the present invention supplies a heat exchange fluid to a rotating load or rotor  13  and is shown in  FIG. 3 . The rotary union  10  includes a rear bushing bearing assembly  30  and a front bushing bearing assembly  35  which both provide support for the union housing with respect to the rotor or shaft  13 . The rear bushing bearing assembly  30  includes a bearing sleeve member  31  mounted for rotation with the rotor  13  and a bearing housing member  32  having an outer curved radial surface  33  mounted within a bore  11   a  of the cylindrical housing  11 , as shown in  FIG. 4 . The bearing housing member  32  includes a graphite wearing portion  34  which is structurally arranged to engage the bearing sleeve member  31  mounted on the rotor to assist retaining the housing  11  in alignment with respect to the rotating load or rotor  13 . The front bushing bearing assembly  35  also includes a bearing housing member  37  having an outer curved radial surface  38  for cooperation with the bore of the housing  11  to facilitate alignment and support of the housing with respect to the rotor  13 . The bearing assembly includes a graphite wearing portion  39  for receiving and engaging the bearing sleeve member  36  which is mounted to the rotor  13 . The front bushing bearing assembly also is structurally arranged to assist retaining the housing within the desired operational alignment with respect to the rotor. 
     In each of the rear and front bushing bearing assemblies, the bearing housing member includes an outer curved radial surface  33  and  38 , respectively, that is structurally arranged to engage the inside surface or bore  11   a  of the cylindrical housing member  11  to properly align the graphite wearing portions of the bushing bearing assemblies with the bearing sleeves mounted to the rotor. The outer curved radial surface  33  of the bearing housing member  32  is best shown in  FIG. 4 . 
     As shown in  FIGS. 3 and 4 , the rotary union  10  further includes a thrust bearing assembly comprised of a metallic thrust plate member  41  that is mounted and secured to the rotor  13  for rotation thereby, a metallic ring member  42  having a spherical contact surface and a carbon graphite spherical ring member  43  positioned between the thrust plate member and the metallic ring member. The carbon graphite spherical ring member presents a mating face at the junction between the counterface of the metallic ring member  42 , which provides a structure which absorbs the mechanical load from the metallic thrust plate member  41 . 
     The rotary union  10  includes also a front seal assembly  47  which is comprised of a rotating seal face member  44  secured to the rotor  13  and rotating therewith and a floating seal face member  45  that is biased by a spring  46  and mounted to the union housing  11 . Engagement of the seal facings of the floating and rotating seal faces occurs when hot oil is passed through the union. This front seal assembly provides a seal which retains the fluid flow within the union  10 . 
     A thrust ring member  48  is mounted to the head or end cap  12  of the cylindrical housing  11  and engages the bearing sleeve member  31  to resist the axial thrust forces within the rotating union  10 . Additionally, a bypass line  50  communicates between the head  12  to an inlet port  52 , which directs a portion of the heated fluid onto the front bushing bearing assembly  35  to lubricate and flush the same. 
     By positioning the rear and the front bushing bearing assemblies  30  and  35 , respectively, within the front sealing assembly  47 , both the rear and the front bushing bearings are situated within the fluid flow of the hot oil within the rotating union. This structure eliminates the need for external lubrication of the bushing bearing assemblies with expensive high temperature greases or lubricants, and there is substantially no change in the physical properties of the hydrodynamic bearing system with the temperature changes required of the pumped fluid within the union. This result occurs because the thrust bearing assembly does not provide any sealing of the rear bushing bearing assembly from the flow of oil or lubricant through the rotating union. 
     A rotating union in accordance with the present invention is operable within ranges of up to 600° F. and up to about 1,000 RPMs.