Abstract:
A rotary piston machine includes a driving part driven by an electric motor, and a driven part that have mutually engaging end-face denticulation for delivering a medium, the driving part and the driven part being housed in a machine housing and connected to the machine housing via respective bottom bearings of the driving/driven parts, creating a unit.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The invention proceeds from a rotary piston machine having end-face denticulation in a driving part and in a driven part and having, disposed between the denticulation, working spaces that increase and decrease in size during the rotation producing the delivery action of the medium, is described in the (older) patent application 10 2004 044 297 A1, which was not pre-published. 
         [0002]    The underlying object of the invention is to improve the rotary piston machine such that it can be produced in a particularly favorable manner without sacrificing the advantages described in the available, older application. 
       SUMMARY OF THE INVENTION 
       [0003]    The rotary piston machine according to the invention has special advantages compared to the aforementioned rotary piston machine. Because of the fact that the driving part and the driven part are arranged within the machine housing and are enclosed by the bottom bearing, it is possible to adjust the clearance retroactively, down to a basic setting, and it is also possible to suppress a subsequent clamping of the running parts, because there is a unit between the bottom bearing and machine housing. Thus, a required axial clearance is retained. 
         [0004]    In accordance with one advantageous embodiment of the invention, for fixing it in the machine housing, the radial edge area of the bottom bearing can be screwed or glued or pressed into a corresponding end-face opening in the machine housing, so that the bottom bearing can be attached to the machine housing in very different manners. What is critical is that a unit is attained. 
         [0000]    For favorable running of the rotors, in accordance with one embodiment of the invention the driving part and/or the driven part has a journal on the side facing away from the pump space, and the bottom bearing has an annular central bearing bore for receiving the journal. According to additional embodiments of the invention, the machine housing embodied as a unit can be admitted into a pump housing that can be closed on the end-face facing away from the electric motor, whereby the pump housing can be embodied in the shape of a pot with a bottom that runs on an incline to a center axis for supporting the bottom bearing of the driven part. 
         [0005]    In accordance with the invention, the space in front of at least one of the driving/driven parts on the side facing away from the pump working space can be connected hydraulically to the pressure side of the pump working space, so that the rotors can be loaded in opposition to one another, whereby bores or channels in the machine housing can provide the hydraulic connection. 
         [0006]    Another embodiment of the invention, a clearance-equalizing catch coupling that is arranged between the shaft end of the electric motor and the driving part, whereby the catch coupling is embodied as an annular/plug-in part having a profiled interior recess for engaging the shaft end of the electric motor and also having an insertion journal for engaging in corresponding openings on the side of the driving part that faces away from the pump space. Such clearance-equalizing catch couplings are known per se, but are novel for a rotary piston machine of the type claimed. Above all, motor conditions are now decoupled from the pump and, vice versa, pump singularities are decoupled from the motor, by means of this clearance-equalizing catch coupling. Decoupling the drive is significant especially by creating a unit between pump parts and machine housing. 
         [0007]    Additional advantages and advantageous embodiments of the invention can be taken from the following description, drawings, and the claims. 
         [0008]    The drawings depict one exemplary embodiment of the subject of the invention and it is described in greater detail in the following. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a longitudinal section, corresponding to the arrow  1  in  FIG. 2 , of a fuel delivery pump with inventive rotary piston machine; 
           [0010]      FIG. 2  is a longitudinal section through this delivery pump corresponding to the line II-II in  FIG. 1 ; 
           [0011]      FIG. 3  is an enlargement of a longitudinal section of a catch coupling of the delivery pump; and, 
           [0012]      FIG. 4  is the axial view of this catch coupling corresponding to the arrow III in  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0013]    The depicted fuel delivery pump has a rotary piston pump  1  and an electric motor  2  that drives the rotary piston pump  1 , and these are arranged in a motor housing  3  and a housing cover  4  attached thereto. This is a highly simplified depiction of the electric motor with a rotor  5 , a magnet ring  6 , and an axial locking part  7  of the motor housing  3  that is connected and sealed thereto. In addition, a pivot bearing  8  of the rotor  5  is provided on this locking part  7 . The fuel flows around the electric motor  5 ,  6  inside the motor housing  3  in order to cool it. 
         [0014]    The second rotational bearing of the rotor  5  is provided at a shaft end  9  thereof in a bearing bore  10  of a bottom bearing  11  that is arranged in a corresponding opening on the end-face of a machine housing  12  of the rotary piston pump  1  and on which a driving part  13  with denticulation on the end-face can be supported. This machine housing  12  is arranged in a pump housing  14  that seals the motor housing  3  and is arranged partially therein and partially within the housing cover  4 . The shaft end  9  projects into a bearing bore  15  that has a large diameter and that runs coaxial with the bearing bore  10  and in which a journal  16 , inserted therein, of the driving part  13  is rotatably borne. 
         [0015]    Arranged in the bearing bore  15 , between the shaft end  9  of the electric motor  2  and the journal  16  of the driving part  13  is a catch coupling  17  as is shown enlarged in  FIGS. 3 and 4 . Since the shaft end  9  is borne in the bottom bearing  11  and also the driving part  13  with its journal  16 , this catch coupling  17  should cause a certain clearance equalization, specifically in both the longitudinal and transverse directions. The bottom bearing  11  is embodied as a fixed bearing and is rigidly arranged between the machine housing  12 , the pump housing  14 , and the magnet ring  6 . 
         [0016]    Two pump rotors work in the machine housing  12 , specifically a driven part  18  in addition to the driving part  13 . The driving part  13  is driven by the shaft end  9  of the electric motor  2  and the catch coupling  17  and transmits its rotational movement to the driven part  18  through denticulation. Cycloid denticulation is provided on the end-faces of the driving part  13  and the driven part  18  and have corresponding working surfaces that face one another. As is shown in  FIG. 2 , this is how pump working spaces  19  are formed between these working surfaces and the inner wall of the machine housing  12 . 
         [0017]    As can be seen from  FIGS. 3 and 4 , the catch coupling  17  has an annular part  20  with a hexagonal interior recess  21  into which a corresponding hexagonal end section of the shaft end  9  of the electric motor  2  is inserted for the desired rotational connection and at the end face of which four insertion journals  23  are arranged that are inserted into corresponding openings arranged on the end-face of the journal  16 . 
         [0018]    An end-face opening in the machine housing  12  is closed on the driven side by a bottom bearing  22  that is arranged coaxially with the driven part  18 . Arranged in this bottom bearing  22  is a bearing bore  24  in which the driven part  18  is borne via a journal  25  thereof. As cannot be seen from  FIGS. 1 and 2 , in addition the driving part  13  and the driven part  18  are loaded in opposition to one another by the hydraulic delivery pressure in which between the pump space on the pressure side and the sides of the driven/driving parts  13 ,  18  facing away from one another a connection is comprised via bores or channels. The driven part  18  is supported with a spherical elevation  26  on a corresponding spherical recess  27  of the driving part  13 . 
         [0019]    As depicted in  FIGS. 1 and 2 , in special cases the pump housing  14  can be embodied in a pot shape, with a bottom  28  that correspondingly runs on an incline to the drive axis but at a right angle to the axis of the driven part  18  and on which the bottom bearing  22  of the driven part  18  is placed and supported. This advantageously provides an additional constructive decoupling of the pump side from the drive side, which can be of particular significance during servicing. All of the features depicted here can be essential to the invention individually and in any combination with one another. 
       LEGEND 
       [0000]    
       
           1  Rotary piston pump 
           2  Electric motor 
           3  Motor housing 
           4  Housing cover 
           5  Rotor 
           6  Magnet ring 
           7  Locking part 
           8  Pivot bearing 
           9  Shaft end 
           10  Bearing bore 
           11  Bottom bearing 
           12  Machine housing 
           13  Driving part 
           14  Pump housing 
           15  Bearing bore 
           16  Journal (of  13 ) 
           17  Catch coupling 
           18  Driven part 
           19  Pump working spaces 
           20  Annular part 
           21  Interior recess 
           22  Bottom bearing 
           23  Insertion journal 
           24  Bearing bore 
           25  Journal 
           26  Elevation on  18   
           27  Recess on  13   
           28  Bottom