Patent Publication Number: US-7582997-B2

Title: Arrangement for conveying fluids

Description:
CROSS-REFERENCE 
   This application is a section 371 of PCT/EP2005/10565, filed 20 Sep. 2005, published as WO 2006-56262-A on 1 Jun. 2006, and claims priority from DE 20 2004 018 752.1, filed 23 Nov. 2004. 
   FIELD OF THE INVENTION 
   The present invention relates to an arrangement for conveying fluids, e.g. liquid and/or gaseous media. 
   BACKGROUND 
   Components having high heat flux densities, e.g. 60 W/mm 2 , are used today in computers. Heat from these components must first be transferred into a liquid circuit, and from there must be delivered via a liquid/air heat exchanger to the ambient air. 
   The discharge of heat from components having a high heat flux density is accomplished by means of so-called heat absorbers or cold plates. In these, heat is transferred to a cooling liquid, and the latter is usually caused to circulate, in forced fashion, in a closed circuit. 
   In this context, the cooling liquid flows through not only the heat absorber, but also a liquid pump that effects the forced circulation and brings about a suitable pressure buildup and volume flow through the heat absorber and an associated heat exchanger, so that the heat transfer coefficients pertinent to these heat exchangers become large, and the temperature gradients necessary for heat transfer become small. 
   A fan, which brings about forced convection of the cooling air on the air side of the heat exchanger as well as good transfer coefficients, is usually arranged on the heat exchanger. 
   Because of the limited space in most electronic devices, the pump and fan must be arranged in as space-saving a fashion as possible, i.e. a compact design is desirable. 
   SUMMARY OF THE INVENTION 
   It is therefore an object of the present invention to make available a novel arrangement for conveying fluids and air to cool the fluids. 
   According to the invention, this object is achieved by arranging a centrifugal pump close enough to a fan motor for magnetic coupling between them, but hermetically separated from each other by a separating can structure. A compact arrangement with good efficiency is thereby obtained. It is particularly advantageous in this context that the motor may have a length that is long in relation to the arrangement, enabling a correspondingly high motor output. 
   The rotor of the arrangement is preferably implemented as a permanent-magnet rotor, which makes possible a compact design, especially when the second permanent magnet is implemented integrally with the permanent-magnet rotor. 
   A design that is particularly short axially results from configuring the fan-side magnet of the magnetic coupling to extend around one of the motor&#39;s rotary bearings and arranging the pump-side magnet of the magnetic coupling to extend axially partially within the fan-side magnet, since as a result thereof, the fan bearing (for the rotor shaft) arranged outside the separating can thereon is located at least in part inside the fan rotor, without negatively affecting the function of the motor or of the magnetic coupling. 
   Another preferred manner of achieving the stated object is to form the fan-side magnet of the coupling pair as an extension of the fan motor&#39;s permanent-magnet rotor. It enables a compact, space-saving design with simple and economical assembly. 

   
     BRIEF FIGURE DESCRIPTION 
     Further details and advantageous refinements of the invention are evident from the exemplifying embodiment, in no way to be understood as a limitation of the invention, that is described below and depicted in the drawings. 
       FIG. 1  is a longitudinal section through a preferred embodiment of an arrangement according to the present invention; and 
       FIG. 2  is an enlarged detail of  FIG. 1 . 
   

   DETAILED DESCRIPTION 
     FIG. 1  is a longitudinal section through an arrangement  120  according to the present invention. The latter has externally an approximately cylindrical fan housing  122  having two flanges  124 ,  126 , at each of whose corners is located a mounting orifice  128 , and which are joined to one another by a tubular part  130 . 
   Flange  126  is joined by struts or spokes  132  to a cover  138  of a pump housing  136 . An inlet tube  140  is located on cover  138 . Cover  138  is joined in liquid-tight fashion to housing  136  in the manner indicated. 
   Cylindrical peripheral portion  144  transitions, to the right in  FIG. 1 , into a portion  148  that extends perpendicular to longitudinal axis  150  of arrangement  120 . This longitudinal axis  150  corresponds to the rotation axis of an electronically commutated internal-rotor motor  152  whose stator is labeled  154 , and whose cup-shaped rotor is labeled  156 . Winding elements of stator  154  are labeled  158 . An advantage of arrangement  120  is that stator  154  and rotor  156  can be long in relation to arrangement  120 , i.e. that a high-output motor  152  can be used. 
   Rotor  156  is mounted on a shaft  160  that has, for its journaling, a left bearing  162  (referring to  FIG. 1 ) and a right bearing  164 . For reasons of service life, these are preferably rolling bearings. The inner ring of left rolling bearing  162  is mounted on shaft  160 . The inner ring of right rolling bearing  164  is arranged displaceably relative to the shaft and is braced by an elastic compression spring  166  relative to rotor  156 ; this spring therefore pushes the inner ring of rolling bearing  164  to the right while it pushes the inner ring of rolling bearing  162  to the left, in order to ensure quiet running of arrangement  120 . 
   The outer ring of rolling bearing  164  is mounted in a tube-like extension  168  of housing  136 , which can also be referred to as bearing tube  168 . A short shaft  170  for a pump wheel  172  of a centrifugal pump  174  is mounted in housing  136  opposite bearing  164 , in the manner depicted. Pump wheel  172  is equipped for this purpose with a sintered bearing  176  that slides on the stationary shaft  170  and forms with it a plain bearing. 
   Shaft  170  is mounted on a portion  180  of housing  136 , which portion extends approximately perpendicular to longitudinal axis  150 . It transitions into a cylindrical part  182  that extends between a hollow-cylindrical permanent-magnet portion  184  of rotor  156  and a hollow-cylindrical extension  186  of pump wheel  172 . As depicted, hollow-cylindrical portion  184  overlaps bearing  164 , resulting in a very compact design. 
   Cylindrical part  182  of housing  136  in turn transitions into an annular portion  188  that proceeds perpendicular to longitudinal axis  150 , and the latter portion transitions in turn into a portion  190  that extends around the outer periphery of pump wheel  176  and transitions into portion  148 . 
   Portions  180 ,  182 , and  188  of housing  136  form a so-called separating can. Because housing  136  is manufactured from plastic, it acts like air in terms of magnetic flux lines but is by nature fluid-tight, so that liquid that flows through inlet  140  into fluid pump  174  is transported by that pump and flows back out through an outlet  192 , as indicated by arrows  194 ,  196 , and cannot emerge out of pump  174 . 
   As depicted in  FIG. 2 , hollow-cylindrical extension  186  of pump wheel  174  is radially magnetized, for example with four poles, usually with the same number of poles as rotor  156 . A magnetic coupling is thereby produced between extension  184  of permanent-magnet rotor  156  and extension  186  of pump wheel  172 ; and when rotor  156  rotates during operation, that rotation is transferred by magnetic coupling  184 ,  186  to pump wheel  172 , so that the latter likewise rotates. 
   As  FIG. 2  shows, pump wheel  172  also has an annular-disk-shaped portion  200  that is implemented as a permanent magnet, and that coacts with the magnetic leakage field at the lower end of rotor  156  and likewise constitutes part of the magnetic coupling, i.e. transfers part of the torque from rotor  156  to pump wheel  172 . 
   Upper bearing  162  (in  FIG. 2 ) of rotor  156  is arranged in a collar  202  of a housing part  204  that, as depicted, can be pot-shaped. This collar transitions, via a kind of bearing bell  206 , into a cylindrical portion  208  that encloses most of stator  154  and ends at a flange  210  that is joined to a flange  212  of housing part  144 , for example, as depicted, via a latching connection by means of multiple latching hooks  213 , only one of which is depicted. The latter are preferably attached on the radially inner side of flange  212 , and make possible very simple assembly. 
   Collar  202  is located in a depression of housing part  204 , and shaft end  214  of shaft  160  projects out of said depression. Pressed onto this shaft end  214 , as depicted, is hub  216  of a pot-like fan wheel  218 , on which fan blades  220  are arranged in the usual way. This fan wheel  218  thus, as it rotates, transports air in an axial direction through fan housing  122 , and this air is preferably used to cool a liquid cooler for the fluid from fluid pump  174 . The fan can, if necessary, also be implemented e.g. as a diagonal or radial fan. 
   Numerous variants and modifications are of course possible within the scope of the present invention.