US2932204A - Polish rod rotator - Google Patents

Description

April 12, 1960 D C, ELVES ETAL 2,932,204

POLISH Ron ROTA'TOR Filed Aug. 20, 1956 www. m 6,2/1

United States Patent POLISH Ron Ro'rA'roR i Douglas C. Elves and Clarence W. Johnson, u Edmonton,-Alberta, Canada This invention relates to polish rod hangers and rotators. Y Y

'In oil well operation, the bottom hole pump is actuated by a-stn'ng of rods, the upper one ofY which is known as 'the polish rod. The rods are reciprocatedby a rock ing beam from which the polish rod is suspended by meansof a suitable hanger. It is also common practice to'provide means for scrapping vaccumulated paraflin andthe like from the walls of the tubing in the well, such*- means commonly comprising s crapers attachedv to the pump rodsand a device -for'frotating the polish and other rods in a clockwise direction looking down the well. V Shouldthe rod string become stuck Vin the hole, damage thereto'frequentlyresults due to the continued rotation -thereof by the rotator, such rotationcausing breakage or'jjamming of the rods `in the hole. Such jamming maybendthe rods beyond "repair "and render it v ery diiicult 'to removethe rod string from 'th hole.

It is an object of this invention to provide improved means for effecting rotation of the pump rods, such means being mechanically simple, inexpensive to manufacture, `and fully satisfactory in operation.

Another object is to provide polish rod rotating means arranged to cease operation in response to a predetermined overload thereby to avoid any damage to the pump rod assembly.

The invention will be described with reference to the accompanying drawing, in which Figure 1 is a perspective view of a general assembly of oil well pumping apparatus in which the present invention is incorporated,

Figure 2 is a sectional side elevation of a rod rotator in accordance with the invention,

Figure 3 is a plan view of the rotator shown in Figure 2,

Figure 4 is a sectional plan view of a modiiied form of rod rotator, and

Figure 5 is a sectional side elevation of the rotator shown in Figure 4.

Referring to Figure 1, 1 is the polish rod, 2 a hanger block suspended by cables 3 from a fitting 4 mounted Von the end of a rocking beam 5, 6 a rotator casing having a cap 7 and an actuating lever 8, and 9 a collar or like clamp member clamped to the polish rod above cap 7. The free end of lever 8 is connected by means of a cable 10 to the beam 5 through an arm 11 clamped to the beam at 12. The polish rod extends loosely through the hanger block and rotator casing, rotator movement to the rod being effected by frictional engagement of the clamp 9 with the casing cap 7 to which rotation is imparted in a manner to be later described. It will be apparent that reciprocation will be imparted to the polish rod and other rods of the string by rocking movement of the -beam 5, and that such movement of the beam will also impart swinging movement to the lever 8, all in a conventional manner.

VReferring to Figure 2,'the casing 6 is of generally'f cylindrical form. Axially and rotatably mounted in the casing is a tube or tubular member 13. Asl shown, a bearing ring 14 is lxed to member 13 and is seated on a ball bearing 15 carried by the bottom wall 16 ofthe casing. Cap 7 is seated on the upper end of member 13" for rotation therewith, clearance between the cap and casing wallpermitting such rotation. A sealing ring 17r is provided between the casing wall and a depending peripheral ange of the cap. It will be understood that the polish rod extends loosely through the ,member 13 and through an axial opening 18 in the cap.

A stub shaft 19 is rotatably mounted in a bearing 20 carried by a radially extending boss 21 in the casing wall, lever 8 being xed to the end of stub shaft 19 to rotate the same. A pin or projection 22 of generally rounded form is eccentrically carried by the face of stub shaft 19 within the casing. Pin 22 ts into a bearing block 23 slidably mounted in a vertical slot 24 in an upper or driving race constituted by an annular member 25. A

one-way clutch 26 is housed in a counter bore 27 in upper race 25. Clutch 26 is of conventional form and tube 13. Upon clockwise rotation of the race 25 the tl'segments of the clutch are wedged somewhat radially between thestube 13 and the race to transmit such rotation to the tube and thereby to the cap 7, clamp 9 and polish rod 1. The segments of the clutch are so inclined toallow a free running counterclockwserota- ,'tion` ofthe upper race 25. ,y

It will thus be apparent that lonY swinging movement of lever 8 in one direction in response to rocking of beam 5, stub shaft 19 will be rotated to in turn impart a degree of rotative movement to the upper race 25 and thus the polish rod and the rod string attached thereto in the manner described.

An important feature of the invention resides in the provision of a holding one Way brake element 28 which comprises an annular member seated on the bearing ring 14 and separated from the upper race 25 by a washer 29. Housed within the element 28 is a one-way brake 30 which may be substantially identical in structure with clutch 26. It permits free rotation of the tube 13 in a clockwise direction relatively to the element 28 but re strains counter-clockwise rotation of the tube relative to the element 28. The holding element 28 is iixed to the casing wall by a shear pin 31 mounted in the casing wall and extending into a slot 32 in the holding element. It will be apparent that each degree of rotative movement imparted to the polish rod and rod string will build up therein frictional and inertia forces which will tend to cause rotation of the polish rod and rod string in a reverse direction as soon as the driving force imparted thereto through the clutch 26 is released. It will also be apparent that the brake element 28 and brake 30 will act to prevent such reverse rotation. Should, however, the rod string become stuck in the well and an excessive build up of torsional stress be thereby induced therein by a degree of rotative movement imparted through clutch 26, the resulting much increased force tending to Irotate the polish rod and string in a reverse direction will impose a correspondingly increased torque on the brake element 28 and its mounting pin 31. The pin 31 is adapted to shear under such increased torque thus relieving the torsional strain on the rods and possible damage thereto.

It will be observed that the shear pin may be easily replaced as required. This safety device eliminates the possibility of imposing torsional stresses on the rods beyond their elastic limit, which stresses would cause fail PatntedApa-ia 1960";

ure of ,'theirods.; ordeec'tion rendering them useless for furtherservice..

A sealing ring 33 may be provided between the lower end of the tube 13 and thebottom wall of the casing. Itvwill be apparent that-lubrication .ofi the mtatoris easilyr and; substantially'permanently; eected'by til-ling the casing6 with grease, the seals 17 and 33 preventing leakagel of lubricant .and inlltrationof foreignV matter.

Figurel illustrates a slightlyjmodiied form,Y of rotator whereinV the stub shaft 19f carries an eccentric pin 34; onA which a roller- 35 is mounted for direct engagement` with a complementary slot 36 (corresponding toslot 24,) in the driving race 25.

Referring to Figures 4 and 5, ,a somewhat diierent arrangement ofY rotating mechanism for` the tube, 13 is provided. TheF actuating' lever Sis arranged to intermittently rotate a stub shaft 37 mountedin bearings 38 in a hqnusing` 39.-.carried bythe rotator fcasing 6. The. stub shaft 37Y has an` enlarged portion40 in which visj mounted'.V

anne-way driving clutch 41, whiehengages one endvof a coaxial, shaft 42 rotatably supported inA housing 39bybearings 4 3. The othervend,` ofshaft 424 is engaged by a one-way holding clutch 44 also mounted in the housing.l The clutch 41 is arranged to drive shaft 42 when stub shaft 37 is rotated in a clockwise direction but slips on shaft 42 when the stub shaft rotates in counter clockwise direction. The shaft 42 therefore rotates intermittently in a clockwise direction, and is restrained from counter clockwise motion by the holdingV clutch 44.

The holding4 clutch 44 Iis restrained from counter clockwise motion relative to the housing by means of a shear key 45` between the clutch 44 and housing 39. Key t 45 is arranged to shear at a. predetermined torque exerted by the clutch 44, thus providing a safety feature` corresponding to that providedlby the'shear key 31`V in the modication of Figure 2. f

Keyed to shaft 42is a worm gear 46 which drives-*a gein'.V 41 mounted on and keyed tothe tube 13. Thus the..

center tube 13, cap 7, clamp 9 and polish rod 1 will be intermittently rotated in a clockwise direction as in the previously described modification.

I claim:

A polish rod rotator comprising a substantially cylindrical casing, a center tube rotatably and axially mounted 'in the casing and arranged to receive the polish rod, a

1 center tube in response to rotation of 'said clutch race in one direction and permitting relative rotation of said center-.tube in the oppositeudirection, a one-way brake element mounted on said center tube, and having a one-- way brake connecting it with said center` tube to restrain rotation of said center, tube inthe opposite direction,

anda shear pin connecting saidcasingand said one-way..

brake element and arranged to shear in response to a predetermined torque exerted thereon.

References Cited in the ile of this patent UNITED STATES PATENTS 529,323` Edmonds NOV. 13, 1894 1,462,721 Sargent July 24, ,1923,-v l,6,33,092 Gribble lune 21, 1927 2,599,869 Shelton June 10, 19,524, 2,603,098 Cremeens July 15, 1952 2,660,893 Paterson Dec. l, 1953A

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