Abstract:
An oil separator for oil-flooded rotary vane vacuum pumps has a filter housing ( 10 ) and a plurality of filter cartridges ( 14 ) disposed therein through which the pumping medium flows. The filter cartridges ( 14 ) are each inserted through a respective opening ( 16 ) in an outer housing wall ( 12 ) of the filter housing ( 10 ) and are secured to the housing wall ( 12 ) so as to be detachable and tight with respect to media.

Description:
FIELD OF THE INVENTION 
   The present invention relates to an oil separator for oil-flooded pumps, in particular rotary vane vacuum pumps, comprising a filter housing and a plurality of filter cartridges disposed therein through which the pumping medium flows. 
   BACKGROUND OF THE INVENTION 
   In oil-flooded pumps, in particular rotary vane vacuum pumps, the pumping medium is directed through an oil separator on the delivery side of the pump in order to separate it from oil carried along with the medium and to recycle the oil into the oil bath. The oil separator is essentially formed by a set of filter cartridges which are disposed in a filter housing and through which the pumping medium flows. The filter cartridges need to be replaced at regular intervals. The filter housing has a housing cover or a special maintenance cover which can be removed after a few fastening screws have been unscrewed for providing access to the filter cartridges. Each filter cartridge is secured in the filter housing by a threaded plastic holder. Once the plastic holder has been released, the filter cartridge can be pulled out of the filter housing. 
   SUMMARY OF THE INVENTION 
   The invention provides an oil separator for oil-flooded pumps which substantially facilitates the replacement of the filter cartridges. According to the invention, the filter cartridges are each inserted through a respective opening in an outer housing wall of the filter housing and are secured to the housing wall so as to be detachable and tight with respect to media. In this way, each filter cartridge is accessible directly at the housing wall of the filter housing so that it is not necessary to remove a housing lid or maintenance cover when the filters are replaced. This greatly simplifies the replacement of the filter cartridges. 
   In a convenient configuration of the attachment of the filter cartridges to the housing wall of the filter housing, such replacement can be accomplished quickly and effortlessly. In the preferred embodiment, each of the filter cartridges is secured to the housing wall by a screw-type or bayonet-type lock. The form-fit formations provided on the housing wall of the filter housing which are required for this type of attachment means are preferably formed not directly on the housing wall itself, but rather on mounting rings inserted therein. This measure simplifies the manufacture of the filter housing. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further features and advantages of the invention will be apparent from the description given below of a preferred embodiment and from the accompanying drawings to which reference is made and in which: 
       FIG. 1  shows a diagrammatic perspective view of a filter housing with filter cartridges inserted through a housing wall; and 
       FIG. 2  shows a view of a section through a filter cartridge and the adjacent wall parts of the filter housing. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The filter housing  10  shown in  FIG. 1  belongs to an oil-flooded rotary vane vacuum pump (not shown) and is applied to the side of the pump structure. The generally parallelepipedal filter housing  10  has an outside housing wall  12  through which four filter cartridges  14  are inserted. Access to the filter cartridges  14  is provided directly on the housing wall  12 . The filter cartridges  14  are each detachably secured to the housing wall  12  by a bayonet-type or screw-type lock and so as to be tight with respect to media. 
   The housing wall  12  has a circular through opening  16  for each of the filter cartridges  14 . Each through opening  16  has a mounting ring  18  inserted therein. The mounting ring  18  has a short, hollow cylindrical muff having a peripheral groove in which a sealing ring  20  is placed. The mounting ring  18  further has an annular flange  18   a  which is inserted in an appropriate recess  12   a  of the housing wall  12  so as to be flush with it. Furthermore, the mounting ring  18  is provided with latching members  18   b  engaging the inner side of the housing wall  12  so that the mounting ring  18  is fixed in place in the housing wall  12  by means of the annular flange  18   a  and the latching members  18   b . The defined rotational position of each mounting ring  18  in its associated through opening  16  is determined by an integrally formed knob  19  which engages in a respective notch of the through opening  16 . 
   The mounting ring  18  receives an outer end piece  22  of the filter cartridge  14  and is provided with form-fit formations on the inside which cooperate with corresponding outer form-fit formations on the end piece  22  in the form of a screw-type or bayonet-type lock. The lock has a pitch such that when the filter cartridge  14  is rotated it forces the latter to make a slight axial movement at the same time. The lock further has a stop for ensuring a defined rotational position of the filter cartridge  14  in the final position thereof. In addition, a grip  24   a ,  24   b  is integrally formed on the outside of the end piece  22 , the grip being in the form of radial ribs with a central hexagonal member  24   c  being disposed in between for engagement by a tool if required. A hollow cylindrical filter body  28  of the filter cartridge  14  is arranged between the outer end piece  22  and a generally annular inner end piece  26 . The end piece  26  is inserted in a through opening  30  of an inside wall  32  of the filter housing  10  which is opposite to the housing wall  12 . The end piece  26  has a generally hollow cylindrical guide collar  26   a  having a peripheral groove in which a sealing ring  34  is inserted. The guide collar  26   a  is tapered toward its free axial end to form guide faces  26   b . These guide faces  26   b  facilitate the insertion of the end piece  26  into the through opening  30  of the wall  32  from the outer side of the housing wall  12 . The outer end piece  22  is also provided with a peripheral groove in which a sealing ring  36  is inserted. This sealing ring  36  seals at the inner periphery of the mounting ring  18 . The sealing ring  34  seals at the inner periphery of the through opening  30  in the wall  32  of the filter housing  10 . The filter body  28  of each filter cartridge  14  is provided with a drop collector  29  which in the correct fitting position protrudes vertically downward. For replacing the filter cartridges  14 , the respective end pieces  22  are grasped at the grip  24   a ,  24   b  and turned counter-clockwise through 90°, resulting in the screw-type or bayonet-type lock to be released. In case of a tight fit of a filter cartridge, a conventional tool may be applied to the hexagonal member  24   c . When the filter cartridge  14  is rotated, it is moved axially at the same time, forcing the sealing rings  34 ,  36  to execute a sliding movement on their sealing surfaces. Each filter cartridge  14  is then pulled axially out of the filter housing  10 . A new filter cartridge is introduced through the mounting ring  18  and advanced against the wall  32 ; the guide faces  26   b  contact the inner rim of the through opening  30  and automatically lead the end piece  26  into the through opening  30 . The fitting process for each filter cartridge is concluded by turning the outer end piece  22  clockwise through 90° as far as to the stop. In the rotational position now reached by each filter cartridge  14 , its drop collector  29  is directed vertically downward, so that an optimum function is ensured.