Abstract:
A pump insert of a vane-type pump having no dedicated housing, the insert being inserted in a gear housing.

Description:
BACKGROUND 
     The present invention relates to a pump insert of a vane-type pump without its own housing. Pump inserts of this kind are used in a wide variety of fields of application in already existing machine housings, such as, for example, in transmission housings of motor vehicles or in other housings where a hydraulic supply is required. However, it is disadvantageous that the fastenings, constituted of screws, covers or the like, that are used for the pump insert in the corresponding housings, are costly, space-consuming and complex. 
     SUMMARY OF THE INVENTION 
     It is, therefore, an object of the present invention to devise a pump insert of a vane-type pump that will overcome these problems. 
     An object of the present invention is to provide a pump insert of a vane-type pump without its own housing that is used in a transmission housing, for example, of a motor vehicle, the pump insert having a first pressure plate, a contour ring, a rotor, a drive shaft, which drives the rotor, vanes, and a second pressure plate, and is axially secured in position in the transmission housing at the second pressure plate by a retaining ring. 
     An advantage of the present invention is there is no need for a second transmission housing part, such as a cover, for example, or for expensive fastening means, such as screw connections or the like. Another advantage is derived in that, due to the retaining ring installed in the transmission housing and at the second pressure plate, no axial forces act on an additional housing component; rather, these forces act within one single housing component and thus not on a second housing component via connection points. 
     A pump insert according to the present invention has the distinguishing feature that the first pressure plate is axially pressed by a pressure field against the contour ring, and against the second pressure plate and the retaining ring. 
     Here, the benefit is derived that the contact pressures of the pressure field keep any leakage within the pump insert to a minimum and ensure a secure contact-making on the retaining ring, thereby effecting a good sealing action and a pump insert operation that is characterized by little play. 
     A pump insert is also preferred where the pressure field has an annular form. In addition, a pump insert is preferred where the annular pressure field extends from the outer circumference of the first pressure plate radially inwardly. 
     Here the advantage is derived that the contact pressures of the pressure field act outwardly at the first pressure plate via the lifting ring on the outer circumference of the second pressure plate, thereby avoiding a bending under load in the inner radial portion of the pump insert, which, in some instances, would lead to deformation and pinching. 
     Another pump insert according to the present invention has the distinguishing feature that the first pressure plate has two seals. A pump insert is also preferred where the first seal of the first pressure plate is configured radially outwardly at the periphery, and the second seal of the first pressure plate axially inwardly at the pressure field. 
     In addition, a pump insert is preferred where, in the unpressurized state, the second axially configured seal is effective as an axial preloading element and, in the unpressurized state, presses the pump insert against the retaining ring. 
     Here the advantage is derived that the pump insert is already effectively sealed in the unpressurized state and exhibits small gaps, making it possible to avoid starting problems caused by leakage. 
     A pump insert according to the present invention has the distinguishing feature that the axial seal is designed as a combination seal that is composed of a sealing and a supporting element. In addition, it is conceivable for separate spring devices to be provided that press the pump insert against the retaining ring. 
     Another pump insert according to the present invention has the distinguishing feature that the second pressure plate has a radial seal on the outer circumference thereof that seals against the transmission housing. A pump insert is also preferred where the second pressure plate has a shaft sealing ring in the bearing area of the shaft. 
     A pump insert according to the present invention also has the distinguishing feature that the support geometry for the retaining-ring groove is implemented in the transmission housing, and the contact surface at the second pressure plate is designed to be self-restraining. In particular, the angles in the supporting area of the retaining ring differ from one another essentially by five degrees. 
     A pump insert is also preferred where the supporting angle in the housing is 25 degrees. A pump insert is also preferred where the supporting angle of the retaining ring at the second pressure plate is 30 degrees. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is described with reference to the figures, which show: 
         FIG. 1  a partial section of a pump insert according to the present invention in a transmission housing; 
         FIG. 2  the support geometry of the retaining ring in a magnified view. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a partial section through a transmission housing  1  having a pump insert  5  according to the present invention. A transmission housing  1  includes a stepped blind hole  3  in which pump insert  5  is configured. Pump insert  5  has a first pressure plate  7 , a contour ring  9 , a rotor  11  and a second pressure plate  13 . Configured radially displaceably in slots of rotor  11  are vanes  15  which, in response to rotation of rotor  11 , move by their upper vane edge along the contour of contour ring  9 . Cells are formed between two adjacent vanes  15  in conformance with the contour of contour ring  9 . Depending on the contour section, these cells increase or decrease in volume and, in the process, suction oil and discharge it again. Rotor  11  is driven by a drive shaft  17  by way of a toothing  19 , in this case, drive shaft  17  being driven via a sprocket wheel  21  or, in some instances, via another drive element, such as toothed wheels or a belt drive. In this context, shaft  17  is cantilevered in second pressure plate  13 . A bearing arrangement in both pressure plates would be likewise conceivable, however. Pump insert  5  is axially secured in position in transmission housing  1  by a retaining ring  23 ; in transmission housing  1 , an approximately part-circular groove  25  being configured in which retaining ring  23  is located in position, while retaining ring  23  rests on an incline  27  on second pressure plate  13 . First pressure plate  7  has a radial seal  29  and an axial seal  31  which seal a pressure field  33  between transmission housing  1  and first pressure plate  7 . Thus, pressure field  33  extends from the radially outer periphery of first pressure plate  7  to the radially inner area delimited by sealing device  31 . In the radially inner region of seal  31  about the axis of drive shaft  17 , pressure plate  7  is not subject to pressure load, so that pressure field  33 , which extends annularly around pressure plate  7 , applies an axial force to contour ring  9  and second pressure plate  13 , essentially in the outer region of pressure plate  7 ; second pressure plate  13  then being pressed against retaining ring  23  which, in turn, introduces the axial forces via housing groove  25  into transmission housing  1 . Since, on the housing side, the axial forces only act within one component, namely transmission housing  1 , and not, as under the related art, through multi-part housings having corresponding housing partitions which, under axial forces, may have expansion joints, a very good fastening of the pump insert is hereby provided, thereby minimizing any danger of deformation and misalignment of the pump insert in a corresponding housing. A misalignment of the pump insert could lead, for example, to acoustical problems and/or to a reduction in the bearing service life due to edge loads and/or to gaping of components and thus to leakage, respectively to degradation of the suction properties and/or to a reduced hydraulic efficiency due to the deformation of the pressure plates of the pump supported on the transmission housing. 
     Since the axial forces of pump insert  5  are transmitted at a considerable distance, namely at the periphery of pump insert  5 , the deformation of pressure plates  7 ,  13  in the middle region of pump insert  5  is minimized. Also, retaining ring  23  makes possible a uniform transfer of forces at the periphery, so that smaller, more uniform deformations of the second pressure plate are made possible and misalignments of the pump parts are reduced. Thus, the inventive features of this pump insert  5  having the retaining ring installation lead to a simpler structural design of transmission housing  1  and to weight optimizations since fewer components are needed. Also, pressure plate  13  of pump insert  5  may have a smaller diameter design since the retaining ring makes it possible for the support to be manufactured with radially smaller dimensions than, for example, when screws or the like are used. Pump insert  5  is axially fixed in position in the unpressurized state, i.e., out-of-operation, when no axial pressure field is present in region  33 , by sealing device  31 , which is designed as an axially preloading element having a corresponding spring action. In this inventive variant of a pump insert  5  having the retaining ring fastening, pump insert  5  is pressed somewhat deeper into transmission housing  1  in order to install retaining ring  23 . To that end, a corresponding deflection of sealing device  31  is provided. Therefore, in the case of sealing device  31 , it may also be practical to use a combination seal, composed of a sealing element and a supporting element, in order to bridge the gap enlarged by the increased installation clearance. 
     In a magnified view in region A,  FIG. 2  shows the geometry in the supporting area of retaining ring  23 . The angles in the supporting area of retaining ring  23  are unequal in size in transmission housing  1  and on second pressure plate  13 ; in this case, they differ by about five degrees. Thus, retaining ring  23  engages in the approximately semicircular groove  25  of transmission housing  1  at an angle  35  of about 25 degrees, while it rests on incline  27  of second pressure plate  13  at an angle  37  of about 30 degrees. As a result, the supporting area of retaining ring  23  is designed to be self-restraining. 
     The design approach according to the present invention for a pump insert  5  for a transmission pump in a vane type of design is particularly useful in this application for fastening the pump in the transmission inexpensively and with minimized constructional outlay, given existing space requirements. Particularly advantageous in this context is the combination of a pump insert  5  without a pump housing, with axial force acting on one side via a pressure field and transfer of the axial force by a retaining ring. 
     List Of Reference Numerals 
       1  transmission housing 
       3  blind hole 
       5  pump insert 
       7  first pressure plate 
       9  contour ring 
       11  rotor 
       13  second pressure plate 
       15  vane 
       17  drive shaft 
       19  toothing 
       21  sprocket wheel 
       23  retaining ring 
       25  groove 
       27  incline 
       29  radial seal 
       31  axial seal 
       32  radial seal 
       33  pressure field 
       35  25 degree angle 
       37  30 degree angle