Patent Application
20080115926
This invention relates to chemical injection pumps, and more particularly to an improved apparatus and production method for controlling a stroking action of the chemical injection pump.
Chemical injection pumps are used, for example, to inject a desired amount of a chemical into an oil and/or gas well or into surface production facilities for the oil and gas. Some chemical injection pumps control a stroke amount and stroke rate via articulation of a microswitch. The microswitch may be actuated, for example, using a collar secured to a portion of a thrust rod of the pump and including one or more projections extending therefrom. The thrust rod is attached to a pump actuator and articulates therewith. However, presently available collars are complex and expensive to manufacture. Thus, it is desirable to have a collar that is usable with different pump models in order to reduce costs, improve part availability, and simplify manufacturing.
Therefore, there is a need in the art to provide a collar adaptable to different model pumps, improved manufacturability, and having low manufacturing costs associated therewith.
The present invention is directed to a collar assembly for inclusion with, or for a retrofit of, a chemical injection pump and method for manufacturing same. According to one embodiment, the collar assembly is secured to a thrust rod of the chemical injection pump and may include a circular or ring-shaped member having a central opening and a second opening offset from the central opening. The second opening receives a central portion of a continuous U-shaped member, wherein fingerlike extensions at opposite ends of the U-shaped member flank a toggle element of a switching mechanism. The fingerlike extensions actuate the toggle element so as to control a stroke length of the chemical injection pump. Further, the collar assembly has a narrow profile, permitting adjustability along a length of the thrust rod without causing interference with a portion of the pump. According to an embodiment of the present invention, the collar assembly does not require welding and includes a small number of parts. Consequently, the collar assembly of the present invention has lower associated manufacturing costs, a simplified manufacturing process, and reduced complexity, allowing for reduced maintenance and installation times.
The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.
Other aspects of the present invention will be better understood from the following description, along with the accompanying drawings, wherein:
Like reference symbols in the various drawings indicate like elements.
The present invention applies to a collar for a chemical injection pump, such as a pneumatic chemical injection pump. Chemical injection pumps may be used in industries such as oil and gas production, chemical processing, water treatment, and others. Referring to
The pressurized gas 90 is delivered to the pump actuator portion 30 via an inlet port 100 and a conduit 110. The pressurized gas 90 exits the pump 10 via the conduit 110 and an exhaust port 120. The inlet port 100, the exhaust port 120, and the conduit 110 are operably connected by a switching mechanism, such as a microswitch 130 known in the art. According to an embodiment of a chemical injection pump illustrated in
In operation, as the pressurized gas is applied through the inlet port 100 and conduit 110, pressure in the pump actuator portion 30 builds, eventually overcoming the bias of a biasing element 190, such as, for example only, a spring. Thereafter, the diaphragm 50 begins to deflect in the first direction causing the thrust rod 60 to correspondingly stroke in the first direction. Regarding
As the pressurized gas is released, the biasing element 190 overcomes the gas pressure and deflects the diaphragm 50 and the thrust rod 60 in the second direction. The diaphragm 50 and thrust rod 60 continue to move in the second direction as the pressurized gas is released through the exhaust port 120 when the second fingerlike extension 170 engages the toggle element 180. As the thrust rod 60 continues to move in the second direction, the fingerlike extension 170 causes the toggle element 180 to deflect in the second direction. The toggle element 180 continues to deflect in the second direction until the biasing element in the microswitch 130 causes the toggle element 180 to fully deflect in the second direction. Thereafter, the microswitch 130 severs communication between the conduit 110 and the exhaust port 120 and enables communication between the conduit 110 and the inlet port 100. Accordingly, the cycle is repeated.
According to a further embodiment of the present invention, the fingerlike extensions 160, 170 form a continuous U-shaped member 290 that extends through the second opening 240. The use of a continuous member reduces the number of parts needed to assemble the collar assembly 150, simplifies manufacturing, and, therefore, lowers the manufacturing cost of the collar assembly 150. The continuous U-shaped member 290 includes a central portion 300, which is received into the second opening 240 of collar 220. As shown, the fingerlike extensions 160, 170 are substantially parallel and are substantially perpendicular to the central portion 300. However, the scope of the present invention is not so limited, and the angle defined by each of the fingerlike extensions 160, 170 and the central portion may be any acute or obtuse angle providing for contact of the fingerlike extensions 160 or 170 with toggle 180. Further, the central portion 300 may be enlarged such that the central portion 300 and the second opening 240 engage each other in an interference fit. Consequently, no welding is required to assemble the collar assembly 150. According to one embodiment, the central portion 300 is knurled to form an interference between the U-shaped member 290 and the second opening 240, although the central portion 300 may be enlarged by any method. Further, the U-shaped member 290 may be assembled to the circular collar 220 when the U-shaped member 290 forms a substantially linear element. The U-shaped member 290 is inserted into the second opening until the enlarged central portion 300 engages the second opening 240 to form an interference fit. Thereafter, the outer portions of the continuous member 290 are bent to form the fingerlike extensions 160, 170. As explained above, the fingerlike extensions 160, 170 may form any angle with the central portion 300. According to one embodiment, a distance between the inner-facing surfaces of the fingerlike projections 160, 170 defines a stroke length of the chemical injection pump 10, since the fingerlike extensions 160, 170 trigger the microswitch 130 to inject and exhaust the compressed gas into and out of the pump actuator portion 30.
The collar assembly 150 attaches to the pump 10 by sliding over an outer surface of the thrust rod 60 and is positioned so that the toggle element 180 is located in a space defined between the two fingerlike extensions 160, 170, as shown in
As shown in
Moreover, the design of the collar assembly 150 is simple and has a reduced number of components compared with pump actuation assemblies presently available, which results in reduced manufacturing costs and simplifies manufacturing.
A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.
