Pump assembly

Abstract

A pump assembly ( 1 ) includes a rotor shaft, a pump base ( 3 ), a pump housing ( 5 ), a motor housing ( 9 ) enclosing a motor for driving the rotor shaft, and a motor stool ( 7 ) that includes a motor coupling portion ( 13 ) and a pump coupling portion ( 15 ). The pump housing encloses one or more impeller stages ( 10 ) arranged between the motor stool and the pump base. The motor stool is clamped to the pump base by at least two tie rods ( 17 ). The motor stool includes at least two fixation protrusions ( 39 ) each having a protrusion end ( 41 ) in the motor coupling portion. Each of the tie rods is fixed to the motor stool by way of a fastener ( 37 ) at least partially extending through one of the fixation protrusions. Each fastener is only accessible when the motor housing is decoupled from the motor coupling portion of the motor stool.

What is claimed is: 
     
         1 . A pump assembly comprising:
 a rotor shaft extending along a rotor axis;   a pump base;   a pump housing;   a motor for driving the rotor shaft;   a motor housing enclosing the motor;   a motor stool comprising a motor coupling portion and a pump coupling portion, wherein the pump housing encloses one or more impeller stages arranged between the motor stool and the pump base and the motor stool comprises at least two fixation protrusions, each having a protrusion end in the motor coupling portion; and   at least two fasteners;   at least two tie rods, wherein the motor stool is clamped to the pump base by the at least two tie rods and each of the tie rods is fixed to the motor stool by way of one of the fasteners at least partially extending through one of the fixation protrusions, wherein each of the fasteners is only accessible when the motor housing is decoupled from the motor coupling portion of the motor stool.   
     
     
         2 . The pump assembly according to  claim 1 , wherein each of the tie rods comprises a motor stool connection part at a motor stool end portion of each tie rods and a pump base connection part at a pump base end portion of each tie rod. 
     
     
         3 . The pump assembly according to  claim 2 , wherein each of the tie rods comprises a longitudinal panel, wherein:
 the longitudinal panel has a radially outer face and a radially inner face;   the motor stool connection part or the pump base connection part or both the motor stool connection part or the pump base connection part extend inwardly from the radially inner face of the panel towards the rotor axis.   
     
     
         4 . The pump assembly according to  claim 1 , wherein:
 the motor stool is clamped to the pump base by exactly two of the tie rods; and   the fixation protrusions of the motor stool are located at diametrically opposite radial sides of the motor stool.   
     
     
         5 . The pump assembly according to  claim 1 , wherein:
 each of the tie rods extend essentially parallel to the rotor axis; or   the fixation protrusions extend essentially parallel to the rotor axis; or   both the tie rods and the fixation protrusions extend essentially parallel to the rotor axis.   
     
     
         6 . The pump assembly according to  claim 1 , wherein:
 the motor stool comprises at least two radially outwardly open motor stool recesses;   the protrusion end, facing towards the motor housing, is a first protrusion end;   each fixation protrusion comprises a second protrusion end facing towards the pump base and ending in one of the motor stool recesses; and   each of the motor stool recesses accommodates a motor stool connection part of one of the tie rods.   
     
     
         7 . The pump assembly according to  claim 1 , wherein:
 the pump base comprises at least two radially outwardly open pump base recesses;   each of the pump base recesses accommodates a pump base connection part of one of the tie rods.   
     
     
         8 . The pump assembly according to  claim 7 , wherein each of the pump base recesses comprises an anchor face for a positive form locking with a hook face of the pump base connection part of a tie rod. 
     
     
         9 . The pump assembly according to  claim 8 , wherein:
 the anchor face of each pump base recess has an angular orientation with an angle in the range of 0° to 60° with respect to a plane perpendicular to the rotor axis;   a surface normal of the anchor face has a vector component pointing radially inward towards the rotor axis.   
     
     
         10 . The pump assembly according to  claim 7 , wherein:
 at least one of the pump base recesses comprises a securing face for abutting against a radial outer face of a panel of each tie rod;   a surface normal of the securing face has a vector component facing radially inward toward the rotor axis.   
     
     
         11 . The pump assembly according to  claim 1 , wherein a longitudinal panel of each tie rod lies at least partially against a radially outer face of the pump housing. 
     
     
         12 . The pump assembly according to  claim 1 , wherein the circumferential extension of all of the tie rods in cumulation spans over a fraction in the range of 1/18 to ¼ of a circumference of the pump housing. 
     
     
         13 . The pump assembly according to  claim 1 , wherein:
 at least one of the fasteners comprises an engagement means for engaging a tool; and   the engagement means is laterally enclosed by the motor stool.   
     
     
         14 . The pump assembly according to  claim 13 , wherein the protrusion end in the motor coupling portion is laterally enclosed by the motor stool and forms a laterally shielded inner seat for engagement means of the fastener within the motor coupling portion of the motor stool. 
     
     
         15 . The pump assembly according to  claim 1 , wherein:
 at least one of the fasteners comprises a bolt; and   a motor stool connection part of each tie rod comprises a thread for receiving the bolt.   
     
     
         16 . The pump assembly according to  claim 1 , wherein:
 each of the fasteners comprises a nut with an inner thread;   a motor stool connection part of each tie rod comprises a bolt portion with an outer thread, the bolt portion extending through the fixation protrusion for receiving the inner thread of the nut located at the protrusion end facing towards the motor housing.   
     
     
         17 . The pump assembly according to  claim 1 , wherein:
 a motor stool connection part of each tie rod is movable parallel to the rotor axis within a range inside a motor stool recess;   an upper stop is defined by a positive form locking between a hook face of a pump base connection part of the tie rod and an anchor face of a radially outwardly open pump base recess in the pump base.   
     
     
         18 . The pump assembly according to  claim 1 , wherein the pump assembly is a multi-stage centrifugal pump assembly.