Abstract:
A rotating impeller pump having an axial face seal carried on a shaft of the impeller positioned inboard of the impeller has a drive mechanism for the shaft carried seal face commonly driven through a keyway in the shaft which drives the impeller such that both the impeller and shaft seal can be easily removed from the shaft.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to pumps and particularly to rotating pumps employing axial shaft seals. 
     2. Description of the Related Art 
     Impeller type pumps such as regenerative turbine pumps are shaft driven and normally employ housing shaft seals. A typical seal includes a housing carried stationary seal member and a shaft carried rotating seal member with the seal members axially urged into face to face abutment. Since the seal is a wear item, it is necessary to provide access to the seal for disassemblability of the seal and replaceability of the seal or components thereof. This normally involves disassembly of a major portion of the pump to provide access to the seal components. 
     Difficulty in disassembly is compounded by the fact that the rotating portion of the seal must be fixed to the shaft for rotation therewith and axially positioned with respect to the stationary seal portion. 
     Since access to and ease of disassemblability and removability of the shaft seal, the principal wear component of the pump, is a critical factor in pump maintenance, improvement of ease of repair and replacement represents a significant advance in pump design. 
     SUMMARY OF THE INVENTION 
     This invention provides improved assembly, disassembly and repair of pumps and in particular regenerative turbine pumps by providing a pump assembly which includes a housing member defining a turbine chamber and a seal chamber with the turbine chamber closed by an end cap. The shaft extends from a bearing mount through the seal chamber and into an internal recess in the end cap. The shaft passes through a stationary seal face at the entrance to the seal chamber. A rotating seal assembly is positioned on the shaft intermediate the stationary seal member and the impeller and is commonly keyed to the shaft in a key groove in the shaft which receives a locking key positioning the impeller. A snap-ring received in a groove in the shaft provides axial positioning of the rotating seal assembly. By providing a common rotational mount for the impeller and the rotating shaft assembly utilizing a single key groove in the shaft, ease of access, disassembly and removability of the shaft seal is provided. Upon removal of the end cap, the impeller can be slid off the shaft through the open end thus giving direct access to the snap-ring. Because the key groove is common for both the mount of the impeller and the rotating shaft seal, upon removal of the impeller key the seal assembly can be slid off the shaft for replacement. Removal of the rotating shaft assembly provides direct access to the stationary seal ring. 
     In an embodiment of the invention, an impeller pump is provided with a drive shaft having a key groove therein and a rotating shaft seal assembly carried by the shaft is rotationally fixed to the shaft via the key groove which also rotationally fixes the impeller. 
     In an embodiment of the invention, a pump housing is provided having an impeller wheel pumping housing section which includes a seal opening for a shaft seal with a common shaft extending into the seal opening through a stationary portion of a shaft seal, the shaft having a key groove, the rotating assembly portion of the shaft seal being carried on the shaft and keyed to the shaft in the key groove, the impeller being carried on the shaft and keyed to the shaft in the same key groove as the rotating seal assembly. 
     In a further embodiment of the invention, a regenerative turbine pump is provided having a multi-part housing including a bearing housing section, an end-cap section, and a seal and pumping chamber positioned between the bearing section and the end-cap section. A common shaft extends through the bearing section, the seal section and into a portion of the end-cap and is provided with a key groove. An impeller wheel is mounted on the shaft and keyed to the shaft via the key groove. A seal assembly is mounted in the seal area including a rotatable section mounted to the shaft and keyed thereto by the same key groove. A stationary shaft seal portion is carried by the intermediate housing at the juncture with the bearing housing portion. All portions of the shaft seal are accessible upon removal of the end cap, the impeller and the impeller shaft key. 
     Other features and objects of the invention will be apparent to those skilled in the art from the following description of the preferred embodiment. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a fragmentary cross sectional view of a regenerative turbine pump according to the present invention; 
     FIG. 2 is a fragmentary perspective sectional view, with parts broken away of a the impeller-shaft-seal assembly and mounting. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 illustrates a portion of a turbine pump  10  including a bearing assembly housing  11 , an intermediate housing  12  and an end-cap housing portion  13 . The bearing assembly housing contains normal shaft bearings supporting a shaft  14 . The bearing housing  11  may be fixed to the intermediate housing  12  by devices such as bolts  15 . As is well known to those skilled in the art, seal gaskets, stationary o-ring seals or the like may be utilized to seal the housing sections together. The intermediate housing  12  includes an axial end opening  16  defined in an end wall  17 . The opening  16  may be provided with a circumferential seal o-ring groove  19 . The shaft  14  extends through the opening  16  through the stationary portion  20  of a shaft seal. The stationary portion may include a seal housing  21  press fitted into the opening  16  having an internal out-turned flange  22  partially overlying an internal radial wall  24  of the housing  12  which extends radially outwardly from the opening  16  and defines a first end of a pump assembly chamber  26  within the intermediate housing  12 . An inturned flange portion  28  of the seal housing  21  at the axial end of the housing  21  opposite the outturned flange  22  forms an axial stop for a stationary seal ring  30 . Again, an o-ring groove  19   a  may be provided between the seal sleeve and the stationary seal ring. The stationary seal ring receives the shaft  14 , preferably with a very slight inter diameter clearance between the inter diameter of the stationary seal ring  31  and the outer diameter of the shaft. 
     A rotating seal assembly  40  is carried by the shaft in the seal chamber  26  and includes a rotating face seal  41  which is biased against the stationary face seal  30  by biasing members such as springs  42  received in a housing  43  which in turn is non-rotatably carried by a shaft collar portion  44  of a rotating seal sleeve  46 . The shaft sleeve  46  extends along the shaft and may include secondary seal areas such as at  45  for receipt of secondary seals such as o-ring seals. Addition secondary seals may be provided between the rotating seal face member  41  and the seal sleeve  46  such as at o-ring space  47 . 
     The rotating seal assembly is axially fixed to the shaft via a snap-ring  50  received in a snap-ring groove  51  in the shaft. It will be seen that the sleeve  46  is therefore axially held between the snap ring  50  and the trapped o-ring at  47 . A free end section  14   b  of shaft  14  extends beyond the groove  51  and receives the inner hub  60  of an impeller  61 . The impeller  61  is received in an impeller chamber or pump chamber  62  which is may be formed in an axial end counterbore of the intermediate housing. It will of course be understood by those skilled in the art that the pumping chamber  62  may likewise be formed in the opposite axial end of the end cap  13  or be partially formed in each. Moreover, the counterbore may be provided with wear plates, surface treatments or the like. The impeller illustrated is of the type known as a floating impeller and relative axial movement is permitted between the shaft and the impeller. 
     As best shown in FIG. 2, the end section  14   b  of the shaft  14  is provided with an axial key groove  70 . The hub  60  of the impeller is provided with a mating key groove  71 . A key  72  received in the key groove thus locks the impeller rotationally to the shaft. The key groove  70  extends axially of the shaft section  14   b  into the area of the shaft within the seal chamber  26  radially inwardly of portions of the seal sleeve. A drive pin  80  is received through the seal sleeve and extends into the key groove  70  to rotationally lock the rotating seal assembly  40  to the shaft  14 . 
     The end cap  13  is affixed to the intermediate housing  12  and is easily removable therefrom, such as by removing fixture bolts, clamp collar or like attachment devices. Upon removal of the end cap  13 , the impeller  61  can be removed from the key and shaft, the key can be removed from the key groove and the snap-ring  50  released from the groove  51 . It can therefore be seen that the entirety of the rotating seal assembly can now be easily removed along the shaft giving access to the stationary seal face  30  and its mounting sleeve  20 . In this manner the entirety of the seal assembly may be removed, replaced or repaired. By providing a relatively large diameter seal chamber  26 , simple access to all components of the seal assembly is provided. 
     Although I have described my invention with respect to a single disclosed preferred embodiment, it will be readily understood by those of ordinary skill in the art that this invention is equally useful in other embodiments.