CA1264718A - High pressure fluid choke device - Google Patents
High pressure fluid choke deviceInfo
- Publication number
- CA1264718A CA1264718A CA000464039A CA464039A CA1264718A CA 1264718 A CA1264718 A CA 1264718A CA 000464039 A CA000464039 A CA 000464039A CA 464039 A CA464039 A CA 464039A CA 1264718 A CA1264718 A CA 1264718A
- Authority
- CA
- Canada
- Prior art keywords
- plug
- ball screw
- valve
- choke
- flange
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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- Lift Valve (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A high pressure fluid choke device for use in controlling fluid flow from an oil or gas well comprising a choke assembly and an improved choke actuator assembly. The actuator comprises two main components, a plug assembly for sealing the choke valve and a ball screw actuator connected to the plug assembly in a rotationally independent relationship.
A high pressure fluid choke device for use in controlling fluid flow from an oil or gas well comprising a choke assembly and an improved choke actuator assembly. The actuator comprises two main components, a plug assembly for sealing the choke valve and a ball screw actuator connected to the plug assembly in a rotationally independent relationship.
Description
'718 BACKGROUND OF THE INVENTION
, The present invention relates generally to high pressure fluid choke valve devices, and more particularly to choke valve devices designed for use on oil and gas wells.
One of the most potentially dangerous and expensive occurrences confronting the petrochemical industry is well blowouts. One device for preventing blowouts is the hydraulic choke valve invented by Wesley F. Renfro, which is the subject of Canadian Letters Patent No. 1,170,384, issuPd July 17, 1984.
The Renfro device comprises a choke valve housing that includes a high pressure fluid passageway extending therethrough. A choke plug, adapted to fit sealingly against a valve seat in the passageway in order to close the passageway, is rigidly and non-rotatably affixed to one end of a choke actuator assembly which extends longitudinally within the choke valve housing. A worm gear assembly rotates the actuator assembly, which drives a ball screw and causes the actuator assembly and the plug to move longitudinally within the choke housing in alignment with the valve seat to open and close the valve.
Since the ball screw of the actuator assembly must rotate to move longitudinally within the housing, the choke plug is also rotated until it is tightly seated against the valve seat in the high pressure fluid passageway.
When the choke valve is closed, the high pressure in the upstream portion of the choke valve tends to hold the plug against the valve seat with a tremendous force. To retract the plug from the seat, the plug must rotate relative to the ....... ~
~g~7~
valve seat through a substantial angular displacemen-t while it is in contact with the se~t beEore it is actually separated from the seat. The forces holding the plug against the ~eat, combined with a high coefficient of friction between the plug and valve seat, create a high torsional resistance to the rotational opening motion of the valve~ It has been found that under especially high pressure conditions such torsional resistance can strain or stall the motor operating the valve, causing the valve to remain closed. Such high torsional resistance can also cause premature wear and possibly breakage of the plug wear material, damage to the means for mounting the plug to the choke actuatox assembly and a tendency to unscrew the valve seat. The torsional resistance to rotation is also present when closing the valve.
SU~ARY A~D OBJECTS OF TH~ INVE~TION
In view of the foregoing limitations and shortcomings of the prior art devices, as well as other disadvantages not specifically ~entioned above, it should be apparent that there still exists a need in the art for a means for opening and closing a choke valve that does not create potentially damaging and dangerous torsional resistance between the plug and valve seat, especially during unusually high pressure conditions. It is, therefore, a primary object of this invention to fulfill that need by providing a choke device wherein the choke valve operates with a significantly reduced amount of torsional resistance between the plug and the valve seat.
More particularly, it is an important object of this invention to provide a high pressure choke valve wherein the 7~ f~
choke plug can be separated from the valve seat with no or a minimal amount of relative rotational motion between the plug and the valve seat.
It is another object of this invention to provide a high pressure choke valve wherein the choke plug is axially driven into seating engagement with its seat with a reduced amount of torsional resistance.
It is still another ob~ect of this invention to provide a high pxessure choke valve having a rotating actuator means engaged to a choke plug means in a substantially rotationally independent manner.
Briefly described, the aforementioned objects are accomplished according to the invention by providing a high pressure choke valve wherein the choke valve plug is adapted to translate into and out of contact with the valve seat in a substantially non-rotational manner.
The device comprises a choke housing that includes a high pressure fluid pa~sageway extending therethrough. A
choke valve plug, adapted to fit sealingly against a valve seat in the passageway in order to close the passageway, is aEfixed to one end of a choXe actuator assembly in a substantially rotationally independent manner. The non-rotational connection between the plug and actuator assembly is provided axially by engaging an annular flange of the actuator assembly between a thrust bearing and a split bushing disposed within a blind bore located at one end of the plug assembly. A drive means including a worm gear assembly rotates the ball screw actuator assembly, which causes the actuator assembly and the attached plug assembly to move longitudinally within ~he choke valve housing in alignment with the valve seat to open or close the valve. Because the plug and the actuator assembly are substantially rotationally independent, the plug engages the valve seat with mini~al relative rotational movement, thus eliminating the potentially harmful torsional resistance present in the prior art choke valve described above.
With the foregoing and other objects, advantages and features of the invention that will become hereinafter apparent, the nature of the invention may be more clearly understood by reference to the following detailed description of the invention, the appended claims and to the several views illustrated in the attached drawings.
BRIEF DESCRIPTION OF TEIE DR~WINGS
Figure 1 is a cross-sectional perspective view of the choke valve device of the present invention;
F gure 2 is a side elevation view, partly in section, of the valve plug and actuator assembly of the present invention shown mounted within the actuator assembly housing;
Figure 3 is a cross-sectional detail view of the actuator assembly and end cover taken along line 3-3 of Figure
, The present invention relates generally to high pressure fluid choke valve devices, and more particularly to choke valve devices designed for use on oil and gas wells.
One of the most potentially dangerous and expensive occurrences confronting the petrochemical industry is well blowouts. One device for preventing blowouts is the hydraulic choke valve invented by Wesley F. Renfro, which is the subject of Canadian Letters Patent No. 1,170,384, issuPd July 17, 1984.
The Renfro device comprises a choke valve housing that includes a high pressure fluid passageway extending therethrough. A choke plug, adapted to fit sealingly against a valve seat in the passageway in order to close the passageway, is rigidly and non-rotatably affixed to one end of a choke actuator assembly which extends longitudinally within the choke valve housing. A worm gear assembly rotates the actuator assembly, which drives a ball screw and causes the actuator assembly and the plug to move longitudinally within the choke housing in alignment with the valve seat to open and close the valve.
Since the ball screw of the actuator assembly must rotate to move longitudinally within the housing, the choke plug is also rotated until it is tightly seated against the valve seat in the high pressure fluid passageway.
When the choke valve is closed, the high pressure in the upstream portion of the choke valve tends to hold the plug against the valve seat with a tremendous force. To retract the plug from the seat, the plug must rotate relative to the ....... ~
~g~7~
valve seat through a substantial angular displacemen-t while it is in contact with the se~t beEore it is actually separated from the seat. The forces holding the plug against the ~eat, combined with a high coefficient of friction between the plug and valve seat, create a high torsional resistance to the rotational opening motion of the valve~ It has been found that under especially high pressure conditions such torsional resistance can strain or stall the motor operating the valve, causing the valve to remain closed. Such high torsional resistance can also cause premature wear and possibly breakage of the plug wear material, damage to the means for mounting the plug to the choke actuatox assembly and a tendency to unscrew the valve seat. The torsional resistance to rotation is also present when closing the valve.
SU~ARY A~D OBJECTS OF TH~ INVE~TION
In view of the foregoing limitations and shortcomings of the prior art devices, as well as other disadvantages not specifically ~entioned above, it should be apparent that there still exists a need in the art for a means for opening and closing a choke valve that does not create potentially damaging and dangerous torsional resistance between the plug and valve seat, especially during unusually high pressure conditions. It is, therefore, a primary object of this invention to fulfill that need by providing a choke device wherein the choke valve operates with a significantly reduced amount of torsional resistance between the plug and the valve seat.
More particularly, it is an important object of this invention to provide a high pressure choke valve wherein the 7~ f~
choke plug can be separated from the valve seat with no or a minimal amount of relative rotational motion between the plug and the valve seat.
It is another object of this invention to provide a high pressure choke valve wherein the choke plug is axially driven into seating engagement with its seat with a reduced amount of torsional resistance.
It is still another ob~ect of this invention to provide a high pxessure choke valve having a rotating actuator means engaged to a choke plug means in a substantially rotationally independent manner.
Briefly described, the aforementioned objects are accomplished according to the invention by providing a high pressure choke valve wherein the choke valve plug is adapted to translate into and out of contact with the valve seat in a substantially non-rotational manner.
The device comprises a choke housing that includes a high pressure fluid pa~sageway extending therethrough. A
choke valve plug, adapted to fit sealingly against a valve seat in the passageway in order to close the passageway, is aEfixed to one end of a choXe actuator assembly in a substantially rotationally independent manner. The non-rotational connection between the plug and actuator assembly is provided axially by engaging an annular flange of the actuator assembly between a thrust bearing and a split bushing disposed within a blind bore located at one end of the plug assembly. A drive means including a worm gear assembly rotates the ball screw actuator assembly, which causes the actuator assembly and the attached plug assembly to move longitudinally within ~he choke valve housing in alignment with the valve seat to open or close the valve. Because the plug and the actuator assembly are substantially rotationally independent, the plug engages the valve seat with mini~al relative rotational movement, thus eliminating the potentially harmful torsional resistance present in the prior art choke valve described above.
With the foregoing and other objects, advantages and features of the invention that will become hereinafter apparent, the nature of the invention may be more clearly understood by reference to the following detailed description of the invention, the appended claims and to the several views illustrated in the attached drawings.
BRIEF DESCRIPTION OF TEIE DR~WINGS
Figure 1 is a cross-sectional perspective view of the choke valve device of the present invention;
F gure 2 is a side elevation view, partly in section, of the valve plug and actuator assembly of the present invention shown mounted within the actuator assembly housing;
Figure 3 is a cross-sectional detail view of the actuator assembly and end cover taken along line 3-3 of Figure
2; and Figure 4 is an exploded side elevation view, partly in section, of the means for connecting the actuator assembly to the plug assembly.
DETAILED DESCRIPTION OF A PREFERRED EMBODIME~T
-Referring now in detail to the drawings wherein like parts are designated by like reference numerals throughout, there is illustrated in Figure 1 a choke valve device 10.
~4718 Fluids under high pressure enter the device 10 through passagewa~ 12 and exit via passageway 14. Flanges 16 and 18 are adapted to inter-face with a gas well flow line (not shown). A plug 20 moves longitudinally within the device 10 in alignment with passageway 14. Plug surface 22 fits sealingly against the valve seat surface 24 in passageway 14 in order to close off the passageway.
The housing and body elements of the inventive device, as seen in Figure~ 1-3, will now be described in detail. A choke nut 26 secures an actuator assembly body 28 within the main choke body housing 32. A center housing 34 is attached to the actuator asse~lbly body 28 by set screws 36 and is further attached to an aft ball screw housing 38 by cap screws 40. A bearing housing 29 is ~hreaded to the actuator assembly body 28, and an inner housing 42 is rotatably mounted within the aft screw housing 38 by bearings 44. Integrated worm 48 and gear 50 are mounted within a gear case housing 52, which is bolted to the aft ball screw housing 38 by socket screws 54~
The portion of the inner housing 42 extending to the right of the gear casing 52 (as seen in Figures 1 and 2) has two opposing longitudinal slots 79 formed therethrough, and high pressure-re~istant sight glass 58 is sealingly mounted over each slot 79. A rear outer cover 56 is mounted over the sight glasses 58 and the slotted portion of the inner housing 42. Corresponding slots 82 in the outer cover 56 are aligned with the siyht glass 58 and slots 79 such that the slots 79 are visible from without the outer cover 56.
A stop plug 60 is threaded into a bore in the right-hand end of the housing 42 and is secured within the outer cover 56 by an end cap 62 which is bolted to the outer 1~i471~
cover 56 by screws (not shown). The end cap 62 is provided with an orifice 64 through which clear lubricating oil may be added. ~ plug (not shown) fits in and seals the orifice 64.
Seals 46 are provided where needed between the various housing elements as seen in E'igures 1 and 2.
Having now described the housing and body elements, the interior elements and their relationship with the housing and body will now be described in detail. A ball screw 66~
having helical grooves 68 formed therein, is mounted within the bearing housing 29 and the inner housing 42.
Complementary helical grooves 70 are formed in the bearing housing 29 and are aligned with the ball screw grooves 68 so as to form a helical passageway in which ball bearings 72 are located.
~ key 74 operatively engages the gear 50 to the inner housing 42, such that rotation of the worm 48 and gear 50 causes the inner housing 42 to rotate within bearings 44. A
pin 76 extends through an opening in the ball screw 66 and is secured by set screws (not shown). The ends of pin 76 extend into slots 79 of the inner housing 42, and are visible from without the outer cover 56 through sight glass 58 and outer cover slots 82. The rotational motion of the inner housing 42 is transmitted to the ball screw 66 via the pin 76 and rotates the ball screw within the bearing housing 29. When the ball screw 66 rotates, the ball bearing and helical groove arrangement between the bearing housing 29 and the ball screw 66 causes the ball screw to translate longitudinally within the inner housing 42.
As the ball screw 66 moves through the inner housing 42, the pin 76 likewise moves through the slots 79. The location of the pin 76 within slots 79 corresponds to the 71~3 operating position of the choke valve, i.e., when the pin 76 is at the right end (as seen in Figures 1 and 2) of the slots 79, the valve is openl and when the pin 76 is at the left end of the slots 79, the valve is closed.
The plug 20 is rigidly affixed to a plug assembly 78 in a conventional manner, such as a threaded engagement (not shown). The plug assembly 78 is attached to the ball screw 66 by shaft 80 in a rotationally independent manner as described in detail hereinafter. A set screw 94 reinforces the threaded attachment means.
In the prior art Renfro device, the plug assembly 78 would be rigidly connected to the ball screw 66 by a shaft similar to shaft 80, which would be integral with both the plug assembly and the ball screw. Rotating the ball screw in the appropriate direction in the Renfro device causes the ball screw and plug assembly to rotate and move axially within the choke device until the plug sealingly engages with the valve seat to close off the passageway. To retract the plug from the seat in the Renfro device, it was necessary that the plug rotate against the seat while it was in contact therewith for a certain angular displacement before it actually separated from the seat. The forces holding the plug against the seat, combined with the high coefficient of friction between the plug and valve seat, created a high torsional resistance to the operating motion of the valve. The torsional resistance can strain or stall the motor operating the valve, causing the valve to remain closed. The resistance can also cause premature wear or breakage of wear material of the plug, and/or damage to the means connecting the plug 20 to the plug assembly 78.
The present invention is an improvement of the ~tj471~
above-described Renfro device, in that it advantageously includes means for driving the plug assembly axially wi-thin the choke device without creating the potentially harmful torsional resistance of the prior art device.
Referring now to Figure 4, an exploded view of a means for connecting the ball screw 66 to the plug assembly 78 in a substantially rotationally independent relationship in accordance with the present invention is illustrated. The plug assembly 78 has a blind bore 82 formed at the right-hand end thereof opposite the plug 20. A thrust bearing 84 is located at the bottom of the bore 82. Shaft 80 is integrally connected to the ball screw 66 and has an integral, outwardly extending, circumferential flange 86 located at the end thereof. The diameter of the flange 86 is slightly less than the inside diameter of the bore 82 but is greater than the diameter of the shaft 80. A split bushing 88 with a circumferential flange 92 is placed around the shaft 80 between the shaft flange 86 and the ball screw 66. The bushing 88 is then inserted with shaft 80 into the bore 82 and the bushing flange 92 is bolted to the end surface of the plug assembly 78 with screws 90. The flange 86 of shaft 80 is thus interposed between the thrust bearing 84 and the split bushing 88, with minima] axial gaps between each bearing 84, 88 and the bearing surfaces of flanye 86, as can be seen from the broken portion of the plug assembly in Figure 2.
As will be appreciated by those skilled in the art, the arrangement of Figure 4 may be reversed, that is, the shaft 80 may be integrally formed with the plug assembly 78 and the bore 82 and thrust bearing 84 may be provided in the end of the ball screw 66, confronting the plug assembly 78.
i47~8 Operation To operate the device of the present invention, a drive means (not shown) is used to drive worm 48, which in turn drives worm gear 50. Gear 50, is secured to the inner housing 42 by key 74, and accordingly rotates the inner housing 42. The rotational movement of the inner housing 42 is imparted to the ball screw 66 by the walls of slots 79 through the pin 76. Accordingly, rotation of worm 48 results in rotation of the ball screw 66.
Since the bearing housing 29 is stationary and does not rotate with the ball screw 66, the ball bearings 72 in the helical passageways formed between the bearing housing 2~ and the ball screw 66 cause the ball screw 66 to move longitudinally with respect to the bearing housing 29 and the inner housing 42.
When the ball screw 66 moves to the left, as viewed with respect to Figure 2, the flanga 86 on the end of shaft 80 abuts the thrust bearing 84 mounted in the blind bore 82 of the plug assembly 78. The ~lange 86 rotates as it moves longitudinally, engages the thrust bearing 84 and transmits the axial component of the flange 86 motion with minimal rotational motion. Thus, the ball screw imparts an axial force to the plug assembly without causing substantial rotation of the plug assembly. The minimal rotational force transmitted to the plug assembly through the bearing 84 advantageously improves the seating of the plug 20 with the valve seat 24.
When the ball screw 66 is rotated in the opposite direction it will translate axially to the right, as viewed with respect to Figure 2. The right-hand annular surface of _g_ 7~
flange ~6 abuts the left-hand end of split bearing 88 which is bolted to the plug assembly 78. Bearing 88 likewise transmits primarily the axiaL component of the movement of flange 86 and retracts the plug assembly 78 from the valve seat 24 without causing rotation of the plug 200 Accordingly, the torsional resistance between the plug 20 and the valve seat 24 is also avoided when the plug is unseated.
Although only a preferred embodiment is specifically illustrated and described herein, it will be appreciated that many modifications and variations of the present invention are possible in light of the above teachings and within the purview of the appended claims without departing from the spirit and intended scope of the invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIME~T
-Referring now in detail to the drawings wherein like parts are designated by like reference numerals throughout, there is illustrated in Figure 1 a choke valve device 10.
~4718 Fluids under high pressure enter the device 10 through passagewa~ 12 and exit via passageway 14. Flanges 16 and 18 are adapted to inter-face with a gas well flow line (not shown). A plug 20 moves longitudinally within the device 10 in alignment with passageway 14. Plug surface 22 fits sealingly against the valve seat surface 24 in passageway 14 in order to close off the passageway.
The housing and body elements of the inventive device, as seen in Figure~ 1-3, will now be described in detail. A choke nut 26 secures an actuator assembly body 28 within the main choke body housing 32. A center housing 34 is attached to the actuator asse~lbly body 28 by set screws 36 and is further attached to an aft ball screw housing 38 by cap screws 40. A bearing housing 29 is ~hreaded to the actuator assembly body 28, and an inner housing 42 is rotatably mounted within the aft screw housing 38 by bearings 44. Integrated worm 48 and gear 50 are mounted within a gear case housing 52, which is bolted to the aft ball screw housing 38 by socket screws 54~
The portion of the inner housing 42 extending to the right of the gear casing 52 (as seen in Figures 1 and 2) has two opposing longitudinal slots 79 formed therethrough, and high pressure-re~istant sight glass 58 is sealingly mounted over each slot 79. A rear outer cover 56 is mounted over the sight glasses 58 and the slotted portion of the inner housing 42. Corresponding slots 82 in the outer cover 56 are aligned with the siyht glass 58 and slots 79 such that the slots 79 are visible from without the outer cover 56.
A stop plug 60 is threaded into a bore in the right-hand end of the housing 42 and is secured within the outer cover 56 by an end cap 62 which is bolted to the outer 1~i471~
cover 56 by screws (not shown). The end cap 62 is provided with an orifice 64 through which clear lubricating oil may be added. ~ plug (not shown) fits in and seals the orifice 64.
Seals 46 are provided where needed between the various housing elements as seen in E'igures 1 and 2.
Having now described the housing and body elements, the interior elements and their relationship with the housing and body will now be described in detail. A ball screw 66~
having helical grooves 68 formed therein, is mounted within the bearing housing 29 and the inner housing 42.
Complementary helical grooves 70 are formed in the bearing housing 29 and are aligned with the ball screw grooves 68 so as to form a helical passageway in which ball bearings 72 are located.
~ key 74 operatively engages the gear 50 to the inner housing 42, such that rotation of the worm 48 and gear 50 causes the inner housing 42 to rotate within bearings 44. A
pin 76 extends through an opening in the ball screw 66 and is secured by set screws (not shown). The ends of pin 76 extend into slots 79 of the inner housing 42, and are visible from without the outer cover 56 through sight glass 58 and outer cover slots 82. The rotational motion of the inner housing 42 is transmitted to the ball screw 66 via the pin 76 and rotates the ball screw within the bearing housing 29. When the ball screw 66 rotates, the ball bearing and helical groove arrangement between the bearing housing 29 and the ball screw 66 causes the ball screw to translate longitudinally within the inner housing 42.
As the ball screw 66 moves through the inner housing 42, the pin 76 likewise moves through the slots 79. The location of the pin 76 within slots 79 corresponds to the 71~3 operating position of the choke valve, i.e., when the pin 76 is at the right end (as seen in Figures 1 and 2) of the slots 79, the valve is openl and when the pin 76 is at the left end of the slots 79, the valve is closed.
The plug 20 is rigidly affixed to a plug assembly 78 in a conventional manner, such as a threaded engagement (not shown). The plug assembly 78 is attached to the ball screw 66 by shaft 80 in a rotationally independent manner as described in detail hereinafter. A set screw 94 reinforces the threaded attachment means.
In the prior art Renfro device, the plug assembly 78 would be rigidly connected to the ball screw 66 by a shaft similar to shaft 80, which would be integral with both the plug assembly and the ball screw. Rotating the ball screw in the appropriate direction in the Renfro device causes the ball screw and plug assembly to rotate and move axially within the choke device until the plug sealingly engages with the valve seat to close off the passageway. To retract the plug from the seat in the Renfro device, it was necessary that the plug rotate against the seat while it was in contact therewith for a certain angular displacement before it actually separated from the seat. The forces holding the plug against the seat, combined with the high coefficient of friction between the plug and valve seat, created a high torsional resistance to the operating motion of the valve. The torsional resistance can strain or stall the motor operating the valve, causing the valve to remain closed. The resistance can also cause premature wear or breakage of wear material of the plug, and/or damage to the means connecting the plug 20 to the plug assembly 78.
The present invention is an improvement of the ~tj471~
above-described Renfro device, in that it advantageously includes means for driving the plug assembly axially wi-thin the choke device without creating the potentially harmful torsional resistance of the prior art device.
Referring now to Figure 4, an exploded view of a means for connecting the ball screw 66 to the plug assembly 78 in a substantially rotationally independent relationship in accordance with the present invention is illustrated. The plug assembly 78 has a blind bore 82 formed at the right-hand end thereof opposite the plug 20. A thrust bearing 84 is located at the bottom of the bore 82. Shaft 80 is integrally connected to the ball screw 66 and has an integral, outwardly extending, circumferential flange 86 located at the end thereof. The diameter of the flange 86 is slightly less than the inside diameter of the bore 82 but is greater than the diameter of the shaft 80. A split bushing 88 with a circumferential flange 92 is placed around the shaft 80 between the shaft flange 86 and the ball screw 66. The bushing 88 is then inserted with shaft 80 into the bore 82 and the bushing flange 92 is bolted to the end surface of the plug assembly 78 with screws 90. The flange 86 of shaft 80 is thus interposed between the thrust bearing 84 and the split bushing 88, with minima] axial gaps between each bearing 84, 88 and the bearing surfaces of flanye 86, as can be seen from the broken portion of the plug assembly in Figure 2.
As will be appreciated by those skilled in the art, the arrangement of Figure 4 may be reversed, that is, the shaft 80 may be integrally formed with the plug assembly 78 and the bore 82 and thrust bearing 84 may be provided in the end of the ball screw 66, confronting the plug assembly 78.
i47~8 Operation To operate the device of the present invention, a drive means (not shown) is used to drive worm 48, which in turn drives worm gear 50. Gear 50, is secured to the inner housing 42 by key 74, and accordingly rotates the inner housing 42. The rotational movement of the inner housing 42 is imparted to the ball screw 66 by the walls of slots 79 through the pin 76. Accordingly, rotation of worm 48 results in rotation of the ball screw 66.
Since the bearing housing 29 is stationary and does not rotate with the ball screw 66, the ball bearings 72 in the helical passageways formed between the bearing housing 2~ and the ball screw 66 cause the ball screw 66 to move longitudinally with respect to the bearing housing 29 and the inner housing 42.
When the ball screw 66 moves to the left, as viewed with respect to Figure 2, the flanga 86 on the end of shaft 80 abuts the thrust bearing 84 mounted in the blind bore 82 of the plug assembly 78. The ~lange 86 rotates as it moves longitudinally, engages the thrust bearing 84 and transmits the axial component of the flange 86 motion with minimal rotational motion. Thus, the ball screw imparts an axial force to the plug assembly without causing substantial rotation of the plug assembly. The minimal rotational force transmitted to the plug assembly through the bearing 84 advantageously improves the seating of the plug 20 with the valve seat 24.
When the ball screw 66 is rotated in the opposite direction it will translate axially to the right, as viewed with respect to Figure 2. The right-hand annular surface of _g_ 7~
flange ~6 abuts the left-hand end of split bearing 88 which is bolted to the plug assembly 78. Bearing 88 likewise transmits primarily the axiaL component of the movement of flange 86 and retracts the plug assembly 78 from the valve seat 24 without causing rotation of the plug 200 Accordingly, the torsional resistance between the plug 20 and the valve seat 24 is also avoided when the plug is unseated.
Although only a preferred embodiment is specifically illustrated and described herein, it will be appreciated that many modifications and variations of the present invention are possible in light of the above teachings and within the purview of the appended claims without departing from the spirit and intended scope of the invention.
Claims (4)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a high pressure fluid choke valve having a fluid passageway therethrough, a valve seat located in the passageway, and plug means arranged to fit sealingly against the valve seat for closing off the passageway, and means for actuating said plug means, the improvement comprising:
said means for actuating said plug comprising a ball screw having a shaft extending axially from one end thereof and a circumferential flange on the free end of said shaft and means for rotating said ball screw to drive the same axially within said choke valve;
said plug means comprising a cylindrical plug with a plug valve rigidly affixed at one end and a bore at the other end; and two bearings mounted within said bore with the flange rotatably interposed therebetween;
whereby when said ball screw is rotated and driven axially within said choke valve, said ball screw axially drives the plug valve in a substantially rotationally independent relation in alignment with the valve seat to open and close the valve.
said means for actuating said plug comprising a ball screw having a shaft extending axially from one end thereof and a circumferential flange on the free end of said shaft and means for rotating said ball screw to drive the same axially within said choke valve;
said plug means comprising a cylindrical plug with a plug valve rigidly affixed at one end and a bore at the other end; and two bearings mounted within said bore with the flange rotatably interposed therebetween;
whereby when said ball screw is rotated and driven axially within said choke valve, said ball screw axially drives the plug valve in a substantially rotationally independent relation in alignment with the valve seat to open and close the valve.
2. The improvement according to claim 1, wherein one of said bearings is a split bushing with an outwardly extending flange at one end thereof and the other of said bearings is a thrust bearing.
3. The improvement according to claim 2, wherein said split bushing is mounted around the shaft of said ball screw between the ball screw and the circumferential flange.
4. The improvement according to claim 3, wherein the thrust bearing is mounted at the bottom of the cylindrical plug bore, and the split bushing together with the actuator assembly shaft and flange are mounted within said bore such that the flange is interposed in a substantially non-rotational relation between the thrust bearing and the split bushing.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US58498384A | 1984-03-01 | 1984-03-01 | |
| US584,983 | 1990-09-20 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1264718A true CA1264718A (en) | 1990-01-23 |
Family
ID=24339570
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000464039A Expired - Fee Related CA1264718A (en) | 1984-03-01 | 1984-09-26 | High pressure fluid choke device |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1264718A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110355978A (en) * | 2018-03-26 | 2019-10-22 | 科倍隆有限公司 | From the trigger valve throttle device of screw extruder melt conveying, the preparation system with the equipment and with the delivery method of the equipment |
-
1984
- 1984-09-26 CA CA000464039A patent/CA1264718A/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110355978A (en) * | 2018-03-26 | 2019-10-22 | 科倍隆有限公司 | From the trigger valve throttle device of screw extruder melt conveying, the preparation system with the equipment and with the delivery method of the equipment |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |