Patent Application
20180347577
Embodiments disclosed herein relate to pumps, and more particularly, to a modular stub shaft assembly for use, for instance, in the assembly of a centrifugal pump.
Centrifugal pumps, for example, are used to transport fluids by the conversion of rotational kinetic energy to the hydrodynamic energy of the fluid flow. The rotational energy may be provided by an electric motor having a drive shaft rotating an impeller within a volute chamber or casing. The fluid enters the pump impeller along or near to the rotating axis of the impeller and is accelerated by the impeller, flowing radially outward into a diffuser or volute chamber (casing), from where it exits. Thus, fluid enters axially through an eye of the casing, is caught up in the impeller blades, and is whirled tangentially and radially outward until it leaves through circumferential parts of the impeller into the diffuser part of the casing. The flow of fluid gains both velocity and pressure while passing through the impeller.
A stub shaft may be used to interconnect the drive shaft of the motor to the impeller. Thus, one end of the stub shaft is secured to the drive shaft for rotation therewith and an impeller is secured to the opposite end of the stub shaft. Since the stub shaft extends into the volute chamber to position the impeller therein, a fluid-tight seal is formed about a portion of the stub shaft to prevent fluid from leaking out of the chamber where the stub shaft enters the chamber.
In some instances, it may be necessary to change or replace the motor. Since the drive shafts of motors are provided in different sizes, this may also necessitate replacement of the stub shaft.
According to one aspect of the present invention, an assembly is provided for interconnecting a drive shaft of a motor to an impeller of a pump. The assembly includes a stub shaft that has an end with a fastener for connecting the stub shaft to the impeller and an opposite end in the faun of a sleeve having an inner diameter defining a cavity therein. The assembly also includes a separate motor shaft sleeve that has an end inserted and received within the cavity of the stub shaft and secured thereto and an opposite end in the form of a sleeve having an inner diameter defining a cavity therein for receiving, engaging and being secured to the drive shaft of the motor. The inner diameter of the sleeve of the motor shaft sleeve is smaller than the inner diameter of the sleeve of the stub shaft.
According to another aspect of the present invention, a pump is provided. The pump includes a motor having a drive shaft and a volute chamber containing an impeller. The pump also includes a stub shaft having an end with a fastener connecting the stub shaft to the impeller and an opposite end in the form of a sleeve having an inner diameter defining a cavity therein. The pump further includes a motor shaft sleeve having an end inserted and received within the cavity of the sleeve of the stub shaft and secured thereto and an opposite end in the form of a sleeve having an inner diameter defining a cavity therein for receiving, engaging and being secured to the drive shaft of the motor.
According to a further aspect of the present invention, a method of interconnecting a drive shaft of a motor to an impeller of a pump is provided. The method includes a step of selecting a motor shaft sleeve from a set of motor shaft sleeves in which motor shaft sleeves having different inner diameters are provided such that a motor shaft sleeve having an inner diameter that is able to receive and closely matches an outer diameter of the drive shaft of the motor is selected. The method also includes inserting an end of the motor shaft sleeve within a cavity of a sleeve of a stub shaft that is secured to the impeller of the pump within a sealed volute chamber. Further, the method includes securing the motor shaft sleeve to the stub shaft and securing an opposite end of the motor shaft sleeve to the drive shaft of the motor.
The foregoing and other objects, features and advantages of the embodiments disclosed herein should become apparent from the following description when taken in conjunction with the accompanying drawings.
For simplicity and illustrative purposes, the principles of the embodiments are described by referring mainly to examples thereof. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the embodiments. It will be apparent however, to one of ordinary skill in the art, that the embodiments may be practiced without limitation to these specific details. In some instances, well known methods and structures have not been described in detail so as not to unnecessarily obscure the embodiments.
An impeller is located within the volute chamber 16 and is rotated via rotational movement of the drive shaft of the motor. Thus, the fluid enters the pump impeller along or near to the rotating axis of the impeller and is accelerated by the impeller, flowing tangentially and radially outward as shown by the arrows “A” in
A centrifugal pump 24 is shown in
The adapter section 38 includes a modular pump shaft/sleeve assembly 40 as shown in
The stub shaft 42 also includes a proximal end 50 (proximal from the perspective of the drive shaft 28 of the motor 26). As shown in
The motor shaft sleeve 44 also has distal and proximal ends, 56 and 58, respectively (i.e., distal and proximal relative to the drive shaft 28 of the motor 26). The outer diameter of the distal end 56 of the motor shaft sleeve 44 is sized to fit within and substantially fill the internal cavity 54 of the stub shaft 42. The outer diameter of the proximal end 58 of the motor shaft sleeve 44 substantially matches that of the inner diameter of the sleeve 52 of the stub shaft 42. Thus, when the distal end 56 of the motor shaft sleeve 44 is inserted into and received within the stub shaft 42, the proximal end 58 of the motor shaft sleeve 44 abuts against and is aligned with the sleeve 52 of the stub shaft 42.
In the inserted condition discussed above, the motor shaft sleeve 44 is prevented from rotation relative to the stub shaft 42. Accordingly, as best shown in
The proximal end 58 of the motor shaft sleeve 44 includes a sleeve 72 having an inner diameter of a predetermined size defining a cavity therein for accommodating a predetermined-sized drive shaft of a motor. One or more longitudinally-extending open slots 74 may be formed in the proximal end 58 of the motor shaft drive 44 to enable slight expansion or contraction of the inner diameter to ensure that the proximal end 58 of the motor shaft sleeve 44 may be tightly clamped and secured to and about the drive shaft of the motor. If multiple slots 74 are used, the sleeve 72 is provided as a bifurcated sleeve with multiple bifurcated sections.
Thus, one or more socket head cap screws or like fasteners 76 may be applied to the proximal end 58 of the motor shaft sleeve 44 to reduce the size of the slot(s) 74 so that the proximal end 58 of the motor shaft sleeve 44 tightly engages and clamps onto the drive shaft of the motor without slippage. In this manner, rotation of the drive shaft rotates the motor shaft sleeve 44, stub shaft 42 and impeller 34 as a single integral unit. In the assembled condition, none of these components can rotate without the other components rotating at the same speed of rotation.
As stated above, different motors may have drive shafts of different sizes. Accordingly, as shown in
An advantage of the above assembly is that, when a motor requires replacement with a new motor having a different sized drive shaft, the stub shaft 38 may remain while only the motor shaft sleeve 40 is removed and then replaced with a different motor shaft sleeve.
For instance, a method of interconnecting a drive shaft of a motor to an impeller of a pump may comprise the step of selecting a motor shaft sleeve from a set of motor shaft sleeves in which motor shaft sleeves having different inner diameters are provided. Thus, a motor shaft sleeve having an inner diameter that is able to receive and closely matches an outer diameter of the drive shaft of the motor may be selected. The method may also include the step of inserting an end of the motor shaft sleeve within a cavity of a sleeve of a stub shaft. Thereafter, the motor shaft sleeve may be secured to the stub shaft and an opposite end of the motor shaft sleeve may be secured to the drive shaft of the motor.
The method may include positioning a feather key in a keyway formed in an outer diameter of the end of the motor shaft sleeve and aligning the keyway of the motor shaft sleeve with a keyway formed in an inner diameter of the sleeve of the stub shaft such that the feather key is contained within the keyways and prevents relative rotation between the stub shaft and the motor shaft sleeve. Thereafter, a fastener maybe secured within a bore extending radially through the sleeve of the stub shaft and a bore formed in an outer diameter of the end of the motor shaft sleeve to lock the motor shaft sleeve to the stub shaft.
The method may further include a step of securing a bifurcated end of the motor shaft sleeve to the drive shaft of the motor by tightening at least one fastener to thereby compress bifurcated sections of the motor shaft sleeve into tight engagement with the drive shaft of the motor.
The above referenced stub shaft and motor shaft sleeve may be made of stainless steel or other material that resists chipping and rust.
The above description illustrates various embodiments along with examples of how aspects of particular embodiments may be implemented, and are presented to illustrate the flexibility and advantages of particular embodiments as defined by the following claims, and should not be deemed to be the only embodiments. One of ordinary skill in the art will appreciate that based on the above disclosure and the following claims, other arrangements, embodiments, implementations and equivalents may be employed without departing from the scope hereof as defined by the claims. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present invention. The benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential features or elements of any or all the claims. The invention is defined solely by the appended claims including any amendments made during the pendency of this application and all equivalents of those claims as issued.
