Patent Publication Number: US-8113794-B2

Title: Integrated internal gear pump with an electric motor

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Application No. PCT/EP2008/005415 filed on Jul. 3, 2008, which claims priority to DE 10 2007 035 239.7, filed on Jul. 25, 2007. The disclosures of the above applications are incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure relates to a rotor pump. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
     It is generally known that liquids can be delivered and gases can also be compressed by means of rotor pumps. An externally geared inner ring meshes with an internally geared outer ring for this purpose, wherein the inner ring is positioned eccentrically with respect to the outer ring and is driven by a suitable drive unit. If the inner ring has five gears, for example, then these mesh between six gear teeth of the outer ring. The fluid is drawn into five operating chambers and then displaced out of these with each revolution of the inner ring. 
     An internal gear pump of this kind is known from German Patent DE 299 13 367 U1, in which the outer ring is driven using a hollow shaft motor. A rotor bearing a permanent magnet is arranged around the outer ring, wherein the outer ring and the rotor are connected to each other in a suitable manner, so that the rotor can drive the outer ring. It is considered disadvantageous that an internal ring pump of this kind has large dimensions in the radial direction and that a large number of parts are required and must be installed. 
     SUMMARY 
     The present disclosure provides a rotor pump having smaller dimensions and fewer components with about the same delivery capacity. 
     This is attained according to the present disclosure with a rotor pump, in that the outer ring forms the rotor of the hollow shaft motor. 
     The integration of the rotor of the hollow shaft motor into the outer ring has the basic advantage that one component is dispensed with and that at the same time, the radial dimension can be reduced. In addition to saving components, a rotor pump of this kind is also lighter. The installation is also easier, since no rotor must be connected to the outer ring. The inner ring runs loosely along around an axis. It is advantageous that relatively great rotation or tangential forces can be transmitted and that there is no danger that vibrations or extreme temperature fluctuations will cause a detachment of the rotor from the outer ring. 
     A further variant provides that the magnets for the hollow shaft motor are arranged between the gaps of the gear teeth or in the teeth of the outer ring. The installation size is also reduced in this way, since the space between the teeth is utilized to accommodate the magnets for the hollow shaft motor. The magnets can assume herein particular shapes that are adapted to the shape of the teeth. 
     It is provided in one form that the outer ring has recesses for accommodation of the magnets, which are formed by breakthroughs or counterbores. Relatively large magnets can be accommodated by the breakthroughs, whereas magnets can be placed in the counterbores from both sides. 
     The recesses have a basically lenticular cross section in order to be able to optionally utilize the space existing between the gaps located between the teeth. The cross sectional shape of the magnets is correspondingly adapted. 
     Optimal drive forces are generated in that the partition of the stator is equal to the partition of the outer ring or corresponds to a whole number multiple of the partition of the outer ring. 
     In another form, the outer ring is made of aluminum or plastic. In this way, the weight of the rotor pump is further reduced and a rotor such as this can be economically produced. 
     Further features, advantages and details of the present disclosure arise from the dependent claims as well as the following description, in which one form of the present disclosure is described in detail with reference to the drawings. The features represented in the drawing and also mentioned in the description and the claims can be a part of the present disclosure either individually or in any desired combination. 
     Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which: 
         FIG. 1  shows a perspective representation of the rotor pump according to the present disclosure; 
         FIG. 2  shows a plan view of the rotor pump; 
         FIG. 3  shows a lateral view of the rotor pump in the direction of the arrow III according to  FIG. 2 ; 
         FIG. 4  shows a section IV-IV according to  FIG. 2 ; and 
         FIG. 5  shows a section V-V according to  FIG. 3 . 
     
    
    
     The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. 
     In  FIG. 1  a rotor pump identified with reference numeral  10  is represented, with which for example liquid, in particular oil for an engine, such as an internal combustion engine or urea for an exhaust gas purification system, is delivered. The rotor pump  10  is provided for this purpose with an inlet  12  and an outlet  14 . The inlet  12  and the outlet  14  are provided in a housing cover  16 , which is flange connected to a housing pot  18 . The inlet  12  and the outlet  14  change with a change in the direction of rotation. It can be clearly seen that the rotor pump  10  is self-contained and is open toward the outside only via the inlet  12  and the outlet  14 . No drive shaft or the like leads into the rotor pump  10 , so that seals therefor are unnecessary. A rotor pump  10  such as this meets high tightness demands. 
       FIG. 2  shows a plan view of the housing cover  16  and displacement spaces  20  can be seen through the inlet  12  and the outlet  14 .  FIG. 3  shows the rotor pump  10  in lateral view and  FIG. 4  shows the latter in longitudinal section with the housing pot  18  removed. 
     As can be seen in the cross section according to  FIG. 5 , the displacement spaces  20  are formed between an outer ring  22  and an inner ring  24 . The outer ring  22  is internally geared herein and has a total of six inwardly projecting teeth  26  in the shown embodiment, between which are located gaps  36 . The inner ring  24  is externally geared and has a total of five outwardly directed teeth  28 , which engage in the gaps  36  between the teeth. The teeth  26  and  28  mesh and form therein the displacement spaces  20 . In addition, the outer ring  22  and the inner ring  24  are oriented coaxially with respect to each other, whereas their axes  30  and  32  have a distance  34  (eccentricity) with respect to each other. 
     The outer ring  22  forms the rotor  38  of a hollow shaft motor  40  and is rotatably mounted in a stator  42 . This stator  42  has receptacles  44  for reels (not represented) open radially outward and running in longitudinal direction, whereas the outer ring  22  forming the rotor  38  has recesses  46  for magnets  48  ( FIG. 4 ). The recesses  46  of the represented embodiment are herein configured as counterbores, so that a magnet  48  can be inserted from each side. The cross section of the recesses  46  is basically lenticular in shape with a first, radially outer peripheral surface  50 , which is bent around the axis  30 , and a second, radially inner peripheral surface  52 , which follows the profile of the tooth  26 . 
     It can also be clearly seen in  FIG. 5  that a rotation of the outer ring  22  causes a rotation of the inner ring  24  around its axis  32 , so that the teeth  26  and  28  mesh, whereby the size of the displacement spaces  20  are altered. 
     A rotor pump  10  of this kind not only has a simpler design, but also possesses a low weight and can be effortlessly installed, and has in addition a greater delivery volume at about the same rotational speed. The radial dimensions are furthermore relatively small due to the integration of the magnets  48  in the outer ring  22 . It is further clearly visible in  FIG. 5  that the housing of the rotor pump  10 , that is, its housing cover  16  and its housing pot  18 , are not penetrated by any components, and therefore no leakage is to be feared. 
     It should be noted that the disclosure is not limited to the forms described and illustrated as examples. A large variety of modifications have been described and more are part of the knowledge of the person skilled in the art. These and further modifications as well as any replacement by technical equivalents may be added to the description and figures, without leaving the scope of the protection of the disclosure and of the present patent.