Patent Publication Number: US-11649822-B2

Title: Split power gerotor pump

Description:
TECHNICAL FIELD 
     The present disclosure relates generally to a gerotor pump, and more specifically to a split power gerotor pump. 
     BACKGROUND 
     Split power gerotor pumps are known. One example is shown and described in U.S. Pat. No. 10,072,660 titled PUMPING DEVICE FOR PUMPING OIL FROM A STORAGE CONTAINER TO A TRANSMISSION SYSTEM OF A MOTOR VEHICLE to Böhm. 
     SUMMARY 
     Example embodiments broadly comprise a split power gerotor pump including a rotational axis, a shaft, an inner gerotor, an eccentric pocket, and an outer gerotor. The inner gerotor is rotationally fixed on the shaft, rotatable about the rotational axis, and includes n first lobes. The eccentric pocket is rotatable about the rotational axis, and includes a cylindrical bore with a center radially offset from the rotational axis and an outer surface, disposed radially outside of the cylindrical bore and arranged for direct engagement with a gear or a rotor for an electric motor. The outer gerotor includes a cylindrical outer surface installed in the cylindrical bore and n+1 second lobes. 
     In some example embodiments, the split power gerotor pump includes a first port plate fixed to the eccentric pocket on a first axial side and a second port plate fixed to the eccentric pocket on a second axial side, opposite the first axial side. The first port plate has a first orifice for directing a hydraulic fluid into a gap between a one of the n first lobes and a one of the n+1 second lobes, and the second port plate has a second orifice for receiving the hydraulic fluid after relative rotation between the inner gerotor and the outer gerotor compresses the gap. In some example embodiments, a one of the first port plate or the second port plate is integrally formed with the eccentric pocket from a same piece of material. In an example embodiment, the split power gerotor pump has a first seal that seals a first annular face of the other one of the first port plate or the second port plate to a second annular face of the eccentric pocket. 
     In some example embodiments, the split power gerotor pump has a housing with a collection chamber hydraulically connected to the first orifice and arranged for hydraulic connection to a hydraulic sump. In an example embodiment, the shaft extends through an axial entirety of the collection chamber. In some example embodiments, the split power gerotor pump includes an outlet cover fixed to the second port plate and a second seal disposed between the outlet cover and the second port plate for sealing the outlet cover to the second port plate. The outlet cover has a tubular protrusion concentric with the rotational axis for expelling the hydraulic fluid. In an example embodiment, the split power gerotor pump includes a first bearing installed on the tubular protrusion. The outlet cover has a cylindrical protrusion, the second port plate has a cylindrical bore, and the cylindrical protrusion is installed in the cylindrical bore for radially positioning the second port plate relative to the outlet cover. 
     In some example embodiments, the split power gerotor pump includes a second bearing installed in the eccentric pocket for rotatably supporting the shaft. In some example embodiments, the split power gerotor pump includes a housing and a third bearing installed in the housing for rotatably supporting the eccentric pocket. In an example embodiment, the split power gerotor pump includes a third seal installed in the eccentric pocket axially between the third bearing and the outer gerotor for sealing the eccentric pocket to the housing. 
     In some example embodiments, the split power gerotor pump includes a housing and an electric motor. In some example embodiments, the electric motor is fixed to the housing and drivingly engaged with the shaft. In an example embodiment, the split power gerotor pump includes a fourth seal for sealing seal the housing to the electric motor. In an example embodiment, the outer surface of the eccentric pocket has a toothed profile arranged for direct engagement with the gear. 
     In some example embodiments, the electric motor has a stator rotationally fixed to the housing and including a plurality of stator coils, and the rotor rotationally fixed to the outer surface of the eccentric pocket. In an example embodiment, the stator is a magnetic stator and the rotor is a magnetic rotor. In an example embodiment, a straight line extending radially outward from the rotational axis passes through, in order, the inner gerotor, the outer gerotor, the rotor and the stator. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    illustrates a cross-sectional view of a first embodiment of a split power gerotor pump according to an example aspect of the present disclosure. 
         FIG.  2    illustrates front view of a gerotor pump assembly of the split power gerotor pump of  FIG.  1   . 
         FIG.  3    illustrates a cross-sectional view of a second embodiment of a split power gerotor pump according to an example aspect of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present disclosure are described herein. It should be appreciated that like drawing numbers appearing in different drawing views identify identical, or functionally similar, structural elements. Also, it is to be understood that the disclosed embodiments are merely examples and other embodiments can take various and alternative forms. The figures are not necessarily to scale; some features could be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the embodiments. As those of ordinary skill in the art will understand, various features illustrated and described with reference to any one of the figures can be combined with features illustrated in one or more other figures to produce embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. Various combinations and modifications of the features consistent with the teachings of this disclosure, however, could be desired for particular applications or implementations. 
     The terminology used herein is for the purpose of describing particular aspects only, and is not intended to limit the scope of the present disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this disclosure belongs. Although any methods, devices or materials similar or equivalent to those described herein can be used in the practice or testing of the disclosure, the following example methods, devices, and materials are now described. 
     The following description is made with reference to  FIGS.  1 - 2   .  FIG.  1    illustrates a cross-sectional view of split power gerotor pump  100  according to an example aspect of the present disclosure.  FIG.  2    illustrates a front view of gerotor pump assembly  102  of the split power gerotor pump of  FIG.  1   . Split power gerotor pump  100  includes rotational axis  104 , shaft  106 , inner gerotor  108 , eccentric pocket  110  and outer gerotor  112 . Gerotor pump assembly  102  includes the inner gerotor, eccentric pocket and outer gerotor as shown in  FIG.  2   . 
     The inner gerotor is rotationally fixed on the shaft by ground flats  114  (ref.  FIG.  2   ), although other methods (e.g., spline, press-fit, welding, etc.) could be employed. The eccentric pocket is rotatable about rotational axis  104  and includes cylindrical bore  116  with center  118  radially offset from that rotational axis. The eccentric pocket also includes outer surface  120  disposed radially outside of the cylindrical bore. The outer surface is arranged for direct engagement with a gear or an electric motor as described below. The outer gerotor includes cylindrical outer surface  122  installed in cylindrical bore  116 . As best shown in  FIG.  2   , inner gerotor  108  includes 5 lobes  124  and outer gerotor  112  includes 6 lobes  126  for moving a hydraulic fluid through pump assembly  102  as described below. In other words, if the inner gerotor has n lobes  124 , then the outer gerotor has n+1 lobes  126 . 
     Port plate  128  is fixed to eccentric pocket  110  on axial side  130 , and port plate  132  is fixed to eccentric pocket  110  on axial side  134 , opposite axial side  130 . Port plate  128  includes orifice  136  for directing the hydraulic fluid into gap  138  between lobe  140  and lobe  142 , and port plate  132  includes orifice  144  for receiving the hydraulic fluid after relative rotation between the inner gerotor and the outer gerotor compresses the gap. In the embodiment shown in  FIG.  1   , port plate  128  is integrally formed with the eccentric pocket from a same piece of material. Other embodiments (not shown) may include port plate  132  integrally formed with the eccentric pocket, however. 
     Seal  146  seals annular face  148  of port plate  132  to annular face  150  of the eccentric pocket. Housing  152  includes collection chamber  154  hydraulically connected to orifice  128  and arranged for hydraulic connection to a hydraulic sump (not shown). As shown in  FIG.  1   , shaft  106  extends through an axial entirety of collection chamber  154 . 
     Outlet cover  156  is fixed to port plate  132  and includes tubular protrusion  158  concentric with the rotational axis for expelling the hydraulic fluid from the port plate. Seal  160  is disposed between the outlet cover and port plate  132  for sealing the outlet cover to the port plate. Bearing  162  is installed on the tubular protrusion. The outlet cover includes cylindrical protrusion  164 , port plate  132  includes cylindrical bore  166 , and the cylindrical protrusion is installed in the cylindrical bore for radially positioning the second port plate relative to the outlet cover. 
     Bearing  168  is installed in the eccentric pocket for rotatably supporting the shaft, and bearing  170  is installed in housing  152  for rotatably supporting the eccentric pocket. Seal  172  is installed in the eccentric pocket axially between bearing  170  and the outer gerotor, for sealing the eccentric pocket to the housing. 
     In the embodiment shown in  FIG.  1   , split power gerotor pump  100  includes electric motor  174  fixed to the housing by bolts  176 , for example, and drivingly engaged with the shaft. Seal  178  seals the housing to the electric motor. Outer surface  120  of the eccentric pocket includes toothed profile  180  arranged for direct engagement with the gear (not shown). That is, the toothed profile and the gear have complementary teeth that mesh together to drive the eccentric pocket when the gear is rotated. The gear may be driven by a combustion engine, for example, to operate the split power gerotor pump when the engine is running and prevent rotation of the eccentric pocket when the engine is stopped. 
     The following description is made with reference to  FIG.  3   .  FIG.  3    illustrates a cross-sectional view of split power gerotor pump  200  according to an example aspect of the present disclosure. The above description of split power gerotor pump  100  generally applies to split power gerotor pump  200  and 2XX reference numerals correspond to 1XX reference numerals, except as described below. Electric motor  274  includes stator  282  rotationally fixed to the housing and rotor  284  rotationally fixed to outer surface  220  of eccentric pocket  210 . Stator  282  includes stator coils  286 . Stator  282  may be a magnetic stator and rotor  284  may be a magnetic rotor, for example. As shown in  FIG.  3   , straight line  288  extends radially outward from rotational axis  204  through, in order, inner gerotor  208 , outer gerotor  212 , rotor  284  and stator  282 . 
     While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms encompassed by the claims. The words used in the specification are words of description rather than limitation, and it is understood that various changes can be made without departing from the spirit and scope of the disclosure. As previously described, the features of various embodiments can be combined to form further embodiments of the disclosure that may not be explicitly described or illustrated. While various embodiments could have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art recognize that one or more features or characteristics can be compromised to achieve desired overall system attributes, which depend on the specific application and implementation. These attributes can include, but are not limited to cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. As such, to the extent any embodiments are described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics, these embodiments are not outside the scope of the disclosure and can be desirable for particular applications. 
     REFERENCE NUMERALS 
     
         
         
           
               100  Split power gerotor pump 
               102  Gerotor pump assembly 
               104  Rotational axis 
               106  Shaft 
               108  Inner gerotor 
               110  Eccentric pocket 
               112  Outer gerotor 
               114  Ground flats (shaft) 
               116  Cylindrical bore 
               118  Center (cylindrical bore) 
               120  Outer surface (eccentric pocket) 
               122  Cylindrical outer surface (outer gerotor) 
               124  Lobes (inner gerotor) 
               126  Lobes (outer gerotor) 
               128  Port plate (first) 
               130  Axial side (first) 
               132  Port plate (second) 
               134  Axial side (second, opposite first) 
               136  Orifice (port plate  128 ) 
               138  Gap 
               140  Lobe (inner gerotor) 
               142  Lobe (outer gerotor) 
               144  Orifice (port plate  132 ) 
               146  Seal (first) 
               148  Annular face (first) 
               150  Annular face (second) 
               152  Housing 
               154  Collection chamber 
               156  Outlet cover 
               158  Tubular protrusion (outlet cover) 
               160  Seal (second) 
               162  Bearing (first) 
               164  Cylindrical protrusion (outlet cover) 
               166  Cylindrical bore (port plate  132 ) 
               168  Bearing (second) 
               170  Bearing (third) 
               172  Seal (third) 
               174  Electric motor 
               176  Bolts (electric motor to housing) 
               178  Seal (fourth) 
               180  Toothed profile (outer surface  120 ) 
               200  Split power gerotor pump 
               204  Rotational axis 
               208  Inner gerotor 
               210  Eccentric pocket 
               212  Outer gerotor 
               220  Outer surface (eccentric pocket) 
               274  Electric motor 
               282  Stator 
               284  Rotor 
               286  Stator coils 
               288  Straight line