Enclosed drives for connecting progressive cavity pumps to universal joints

Abstract

To solve a problem that a rotor and a universal joint are coupled to each other by a pin and the service life is shortened when an abrasive material enters a pin hole.SOLUTION: A progressive cavity pump includes a sealed drive between a rotor 24 and a universal joint 26. The universal joint includes a socket 38 configured to receive a drive shaft of the rotor. A cover such as a lock nut 28 is disposed over a connection between the rotor and the universal joint. Seals are retained in place by the lock nut to prevent abrasive materials from entering into a joint portion between the rotor and the universal joint.SELECTED DRAWING: Figure 2A

Description

[Technical field]

[0001] The present invention relates to fluid pumps, and more particularly to progressive cavity (PC) pumps. [Background technology]

[0002] PC pumps can be utilized to move viscous materials such as thermal interface materials (TIMs) and can include universal joints for use in such pump systems. In most compositions, TIMs are made of 80-90% aluminum oxide and are highly abrasive to mechanical components, including pump components. Fluid contacting parts for systems pumping TIMs and similar materials must consequently be capable of withstanding extremely severe abrasive wear or be replaced frequently. Frequent part replacement increases operating costs and also requires complex disassembly and reassembly in many systems. Summary of the Invention [Problem to be solved by the invention]

[0003] The rotor part of the PC pump is connected to and driven by a universal joint. A cup forming part of the rotor is connected to the shaft of the universal joint by a pin. This pin is driven through a hole in the cup and shaft. This transmits torque from the drive shaft to the rotor but allows abrasive material to get into the pin hole until the connection breaks. In some cases the rotor and universal joint are assembled together. This increases life but also increases replacement costs. [Means for solving the problem]

[0004] According to one aspect of the disclosure, an assembly for a progressive cavity pump includes a universal joint having a torque input portion at a first axial end and a socket at a second axial end, a screw rotor having a drive shaft disposed in the socket and a pump shaft extending from the drive shaft, and a lock nut connected to the universal joint and securing the screw rotor to the universal joint, wherein the drive shaft has a first contour and the socket has a second contour, the first contour matching the second contour such that the universal joint is capable of transmitting torque to the rotor via a connection between the drive shaft and the socket. [Brief description of the drawings]

[0005] [Figure 1] FIG. 1 is a cutaway isometric view of a progressive cavity pump. [Figure 2A] FIG. 2 is an exploded view of the rotor and universal joint assembly. [Figure 2B] FIG. 2 is a partial cutaway isometric view showing the connection between the rotor and the universal joint. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0006] FIG. 1 is a cutaway perspective view of a progressive cavity (PC) pump 10. The PC pump 10 is capable of pumping highly viscous or granular materials, such as thermal interface materials (TIMs). The progressive cavity pump 10 includes a housing 12, a nozzle 14, a torque input 16, a fluid inlet 18, a stator cylinder 20, and an assembly 22. The assembly 22 includes a screw rotor 24, a universal joint 26, and a number of additional unnumbered parts and subcomponents. The PC pump 10 extends along an axis AA. The axis AA represents both a fluid flow axis and a torque transmission axis. The housing 12 acts as a rigid enclosure for the other components of the PC pump 10 and serves as a structural framework for the PC pump 10, as well as defining an internal fluid flow cavity F within the PC pump 10. Through this cavity, the TIMs flow during operation of the PC pump 10. The nozzle 14 provides an exit opening for the material to exit the PC pump 10. The torque input 16 receives torque, for example, from a motor (not shown) and supplies the torque to the rotor 24 via a universal joint 26. The fluid inlet 18 accepts material (e.g., TIM) into the flow cavity F, which can be supplied, for example, from a dedicated material source by an external material line (not shown). The stator cylinder 20 is a resilient, contoured cylinder, for example, made of rubber or a semi-flexible polymer. The screw rotor 24 is a rigid, screw-shaped body that is snugly housed within the stator cylinder 20. The screw rotor 24 is coupled to the torque input 16 via a universal joint 26. The universal joint 26 transmits the torque while allowing lateral (i.e., radial) displacement of the screw rotor 24 relative to the axis A.

[0007] During normal operation, material enters the PC pump 10 through the fluid inlet 18 and is pumped towards the nozzle 14 by the rotation of the screw rotor 24 in the stator cylinder 20. The screw rotor 24 is driven by the torque input 16 through a universal joint 26. The torque input 16 rotates about an axis AA in a bearing in the housing 12 as shown. In contrast, the screw rotor 24 is offset from the axis AA by, for example, 1-2 mm and orbits the axis AA as it rotates. Specifically, the stator cylinder 20 constrains the screw rotor 24 so that it moves about the axis AA in an orbit that rotates counter to the direction of rotation of the screw rotor 24. The universal joint 26 transmits torque from the axially linearly arranged torque input 16 to the linearly eccentrically arranged screw rotor 24. Meanwhile, the universal joint 26 allows (only) radial translation of the screw rotor 24 as it is required to orbit about axis AA within the stator cylinder 20. The universal joint 26 is constructed to withstand heavy torque and off-axis loads with high durability and simple assembly.

[0008] FIG 2A is an exploded view of assembly 22. FIG 2B is a partial cutaway view of assembly 22 showing the connection between screw rotor 24 and universal joint 26. FIG 2A and FIG 2B are discussed together. Assembly 22 includes rotor 24, universal joint 26, lock nut 28, and O-ring 30. Universal joint 26 includes housing 32, threaded portion 34, torque input portion 36, and socket 38. Rotor 24 includes a drive shaft 40 and a pump shaft 42.

[0009] Assembly 22 forms part of a PC pump, such as PC pump 10 (FIG. 1). Universal joint 26 is disposed between a drive, such as a motor (not shown), and rotor 24. Universal joint 26 receives torque from the motor at torque input 36 and transmits the torque to rotor 24 via a connection between socket 38 and drive shaft 40, driving rotation of rotor 24. Lock nut 28 secures rotor 24 to universal joint 26. Lock nut 28 threads into threaded engagement 34 to secure rotor 24 to universal joint 26. Although lock nut 28 is described as being connected to universal joint 26 via a threaded engagement, it will be understood that lock nut 28 may be connected to universal joint 26 in any desired manner, such as a bayonet connection, among other options.

[0010] An O-ring 30 or other seal is disposed between the lock nut 28 and the universal joint 26 and / or rotor 24 to prevent abrasive materials from entering the connection between the universal joint 26 and the rotor 24. In the illustrated embodiment, a first O-ring 30 is disposed in a seal groove formed on the universal joint 26 and a second O-ring 30 is disposed at a distal end of the universal joint 26. A threaded engagement 34 is disposed between the first and second O-rings 30.

[0011] A drive shaft 40 is disposed within the socket 38. The universal joint 26 transfers torque to the rotor 24 through the connection between the drive shaft 40 and the socket 38. A pump shaft 42 extends from the drive shaft 40 and is disposed within a stator cylinder, such as the stator cylinder 20 (FIG. 1). Rotation of the pump shaft 42 within the stator causes material to be pumped through the PC pump. The assembly 22 allows for replacement of either the rotor 24 or the universal joint 26 without replacing the other part. The drive shaft 40 includes an outer profile and the socket 38 includes a matching profile to facilitate torque transfer. In the illustrated embodiment, the rotor 24 has a square axle drive shaft 40 that is inserted into a square socket 38 at the end of the universal joint 26. The connection is held together by a lock nut 28 sealed at both ends with O-rings 30 to prevent abrasive material from entering the connection. Although the drive shaft 40 and socket 38 are described as having matching square cross sections, it is understood that the drive shaft 40 and socket 38 can be of any desired configuration suitable for facilitating quick connection and torque transfer by insertion of the drive shaft 40 into the socket 38 without the need for additional connectors such as pins. For example, the drive shaft 40 and socket 38 can each have a triangular, rectangular, pentagonal, or any other suitable cross-sectional shape.

[0012] Although the present invention has been described with reference to exemplary embodiments, those skilled in the art will recognize that various modifications may be made and equivalents may be substituted for the elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is not intended that the invention be limited to the particular embodiments disclosed, but rather, it is intended to include all embodiments falling within the scope of the appended claims. [Explanation of symbols]

[0013] 10 Progressive Cavity Pump 16 Torque input section 22 Assembly 24 Screw rotor 26 Universal joint 28 Lock nut 38 Sockets 40 Drive shaft

Claims

1. 1. An assembly for a progressive cavity pump, comprising: a universal joint having a torque input portion provided at a first axial end and a socket provided at a second axial end; a screw rotor having a drive shaft disposed in the socket and a pump shaft extending from the drive shaft; a lock nut that is connected to the universal joint by screwing and fixes the screw rotor to the universal joint by screwing; a first annular seal disposed between the universal joint and the lock nut and surrounded by the lock nut; a second annular seal disposed between the universal joint and the lock nut and surrounded by the lock nut; having the second annular seal is disposed such that a threaded connection is located between the first annular seal and the second annular seal; an assembly, wherein the drive shaft has a first profile and the socket has a second profile, the first profile matingly engaging with the second profile, such that the universal joint transmits torque to the screw rotor via a connection between the first profile of the drive shaft and the second profile of the socket.

2. The assembly of claim 1 , wherein the first profile of the drive shaft has a square cross section.

3. 3. The assembly of claim 1 or 2, wherein the second profile of the socket has a square cross section.

4. The assembly of claim 1 , wherein the first annular seal and the second annular seal each comprise an O-ring.

5. The assembly of claim 1 , wherein the universal joint includes a seal groove adjacent a threaded portion of the universal joint.

6. An assembly according to any one of claims 1 to 5; a stator cylinder, wherein the pump shaft is disposed within the stator cylinder.

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