RU2416015C1 - Hinge of bottom-hole motor - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: hinge includes housing with longitudinal grooves, shaft with spherical support footstep and footstep bearing, restricting bushing keeping the shaft from falling out of housing, and load-carrying elements arranged between housing and shaft. Grooves in housing are made in the form of segmented linear or radial key slots, and load-carrying elements are made in the form of leaf washers or leaf washers at least with one convex spherical surface and blind or through hole in which elastomer spring can be installed.

EFFECT: high load-carrying capacity, long service life, repairability, and cheap manufacture.

5 cl, 3 dwg

Description

The invention relates to rotation drive devices, in particular to swivel torque transmission devices from screw gerotor hydraulic machines, and can be used in downhole screw motors for drilling oil and gas wells, as well as in pumps for pumping fluid to / from a well and other mechanisms with variable axis of rotation.

A cardan shaft is known for connecting a rotor of a screw gerotor hydraulic machine with a spindle (RF patent No. 2285781), which contains a central shaft and two housings, each of which covers the edge of the central shaft, and between each housing and the edge of the central shaft there are a number of balls mounted on one side in hemispherical hollows, for example, the Central shaft, the other side in the longitudinal semi-cylindrical grooves, for example, the housing, with each row of balls forms a hinge mechanism between the Central shaft and the housing, and at least one of the hinge mechanisms is double-row, for example, with a total even number of balls equally spaced around the circumference in two rows equal to the number of balls of a single-row hinge mechanism.

The disadvantage of this device is its small resource due to the increased speed of movement of the balls in the grooves due to their eccentricity relative to the zero position and the wedging effect.

Known articulated device of a gerotor hydraulic machine (RF patent No. 2235228), which contains a gear coupling and a shaft with an axial spherical thrust bearing, as well as a ball through which the axial load is transmitted. The moment from the shaft to the coupling is transmitted through the barrel-shaped teeth of the shaft and the straight teeth of the coupling, and the end profile of the tooth of the connection is made along the envelope of the initial contour of the rack (RBI), outlined by the equidistant of the shortened cycloid; RBI has a variable negative displacement x with respect to its position in the throat section, the maximum value of which depends on the radius of curvature R of the teeth in the longitudinal section and the width b of the shaft crown; the radius of curvature R of the tooth profile in the longitudinal section is determined by the angle of refraction of the hinge axes.

The disadvantages of this device are the complexity of manufacture and a small resource due to the high relative sliding speeds of the teeth, as well as non-repairability.

A known hinge of a downhole screw motor (RF patent No. 76954), comprising a housing with internal longitudinal grooves of a cylindrical shape, a shaft with external longitudinal grooves of a cylindrical shape, a rolling body in the form of rollers having a barrel-shaped outer surface, in which the radius of curvature R1 is made from the ratio R1 = (r + R), where r is the largest radius of the cross section of the roller, R is the radius from the hinge axis to the axis of the roller, and the length of the roller L is made in accordance with the ratio L> 2r installed in the cavities formed by the corresponding olny grooves of the housing and shaft; means for transmitting axial load, consisting of a shaft, the end surface of which is made curved spherical for interacting with a concave spherical surface of the liner installed in the recess of the housing, and also that a damping element is placed between the liner and the housing.

The disadvantages of this device are the complexity of manufacture and a small resource due to the chaotic (uncontrolled) movement of the rollers in the grooves.

A well-known downhole motor hinge (RF patent No. 2206697), which contains a fitting with a step made inside the ledge and an additional support installed in the fitting for interacting the female surface of the additional support with a covered surface made on the shaft shoulder. The male surface of the shaft shoulder and the female surface of the additional support, as well as the shaft end and the bearing surface interacting with the shaft end, are made spherical with the center of the spheres at the intersection of the central axis of the shaft and the plane passing through the centers of the hemispherical shaft key seats.

The disadvantages of this device are the complexity of manufacture and low bearing capacity due to additional sliding elements that reduce the cross section of the shaft and the housing.

The task is to create a hinge for a downhole motor with high bearing capacity, long life, maintainable, technologically cheap to manufacture.

This goal is achieved due to the fact that in the hinge of the downhole motor comprising a housing with longitudinal grooves, a shaft with a spherical fifth support and thrust bearing, and supporting elements (crackers) placed between the housing and the shaft, according to the invention, the grooves in the housing are made in the form of partial linear or radial keyways, the supporting elements are made in the form of sheet washers in the general case, or with at least one convex spherical surface, and an additional hole, through or blind (recess), under the elastomeric th spring; an oil filling hole with a valve is made in the center (along the axis) of the shaft, and an undercut is made in the spherical head of the shaft (to prevent contact with the increased thrust bearing when the shaft is swinging) and there is a side hole in it for oil supply; in the limiter sleeve, the inner hole is made conical, with a cone angle equal to or greater than the maximum angle of rotation of the shaft.

The invention is a hinge downhole motor is schematically illustrated in the drawings:

figure 1 presents a longitudinal section of a hinge;

figure 2 presents a cross-section of the hinge in the center of the axis of rotation of the ball joint of the shaft with the simultaneous display of two options for the implementation of partial linear and radial keyways, as well as two embodiments of the supporting elements (sheet washers with a convex spherical surface): with a hole and a recess under elastomeric spring;

figure 3 presents an enlarged view of two embodiments of partial linear and radial keyways, as well as two embodiments of the supporting elements (sheet washers) with a hole and a recess under the elastomeric spring. Moreover, on the left is a radial groove with a sheet washer with a spherical convex surface and a through hole for the elastomeric spring, and on the right is a linear keyway with a sheet washer with a spherical convex surface and a blind hole (recess) for the elastomeric spring, although their combination may be different.

The downhole motor hinge consists of the hinge body 1, which is attached to the shaft of the spindle support of the downhole motor (BZD) or its drive element (not shown) using a thread (in this case, nipple). A spherical bearing of a shaft 2 with a spherical head of a similar diameter is inserted into a cylindrical hole of the housing 1. The other end of the shaft 2 is tapered and / or splined to be attached to the shaft of the spindle support of the downhole motor (BZD) or its drive element 3. From falling out of the housing 1, the shaft 2 is held by a limiter sleeve 4, which is attached to the housing 1 by a screw 5 s end slots where, after screwing the screw 5, the edge of the housing 1 is choked to prevent unscrewing during operation. The elastomeric seal 6 and the cover 7 protect the hinge from getting into the drilling fluid and oil leakage from the hinge to increase its performance. One end of the elastomeric cover 7 is clamped between the limiter sleeve 4 and screw 5, and the other is attracted to the shaft 2 by a worm (or similar) clamp 8. The axial force from the shaft 2 to the housing 1 is transmitted through the spherical heel 9 and the thrust bearing 10, under which in the shaft 2, undercutting is performed in the spherical head G. Oil is filled through the hole in the center of the shaft 2, which is then sealed by the valve 11. The torque from the shaft 2 to the housing 1 (and vice versa) is transmitted through the supporting elements (crackers) 12 or 13, which are placed in cylindrical l units (blind holes) in the shaft 2 and in the general case can be made with sheet washers, but in the drawings they are shown with a convex spherical surface that contacts partial keyways of the housing 1. During operation of the hinge, crackers 12 or 13 will wear out, as well as those in contact with they are the surfaces of the housing 1 and shaft 2, therefore, to prevent the crackers 12 (13) from falling out of their holes or jamming between the housing 1 and the shaft 2, elastomeric springs 14 are provided, and their shape depends on the crackers 12 used with them 13: option 14 and the elastomeric spring 12 backs biscuit inside the cylindrical hole of the shaft 2, and a variant of the elastomeric spring 14 b pushes the biscuit 13 outwardly from its wells.

The operation of the downhole motor hinge is based on the transmission of torque from the downhole motor through the spindle support to the rock cutting tool (cone). In this case, the axis of rotation of the shaft constantly changes its position due to the use of the mechanism for deviating the angle of the well (not shown) and the precession of rotation of the shaft of the gerotor motor. At the same time, the resulting force from the pressure of the working fluid and the weight of the drill pipe string falling on the rock cutting tool passes through the hinge. The hinge is the weakest link in the transfer of loads in the chain of assembly units for the bottom of the drill string (BHA) and acts as a kind of restrictive element in increasing the possible torque and duration of work on the face.

Due to tight dimensional restrictions, increasing the outer diameter of the hinge is not possible, and the main way to increase the cross section of the housing 1 and shaft 2 is to reduce structural cuts in a dangerous section. The transition from balls and rollers in opposed analogues to sheet washers with a possible spherical surface is associated with this. This reduces the depth of the holes in the shaft 2 and virtually eliminates the main disadvantage of the prototypes, leading to premature destruction of the hinge - wedging effect in contact on the side surfaces of the housing 1 and shaft 2 with bearing elements in the form of balls and rollers.

Crackers 12 (13) in the form of leaf washers in the proposed hinge design work only for cutting, and in the shaft 2 they are made of cylindrical holes with a depth close to half the thickness of the sheet washer 12 (13). In case 1, for the remaining ½ ... 2/3 parts of crackers 12 (13), keyways (according to the number of crackers 12 or 13) are made, linear or radial, which are then opened with a cylindrical hole equal in diameter to the spherical shaft head 2, which generally passes through symmetrically located concentric centers of the ends of the keyways. As a result, in the housing 1 receive longitudinal grooves in the form of partial keyways, linear or radial.

The differences between linear and radial keyways are determined mainly by the technology of their implementation: concentric to the axis of the housing 1 or tangentially to it (with symmetry about the center of the groove). By strength and other characteristics, they are almost identical, since the main force falls on the edges of the grooves. The small width of the keyway in the housing 1, together with the shallow depth of the cylindrical hole in the shaft 2 for crackers 12 (13), allows to maximize the diameter of the shaft 2 and the ball head on the shaft 2 in order to increase the maximum torque transmitted by the hinge.

The hole for refueling in the center (along the axis) of the shaft 2 allows you to abandon a similar hole in the prototypes, made in the housing 1 of the hinge. This allows you to reduce the linear dimensions of the housing 1 and eliminate the stress concentrator on its surface. At the same time, the likelihood of depressurization of the valve 11 is reduced due to centrifugal loads during rotation of the hinge. The hole in the center of the shaft 2 in the zone of the neutral axis of loading of the fibers, as is known from the theory of strength, practically does not weaken the cross section.

When using a spherical heel 9 of a smaller diameter than the spherical head of the shaft 2 (to reduce the dimensions of the housing 1) and equal to the diameter of the sphere of the thrust bearing 10 (to increase the bearing area and reduce wear), undercutting of the shaft 2 of the shaft 2 is performed undercutting G. Using it eliminates the contact of the shaft 2 with the thrust bearing 10 during rotation (swinging) of the shaft 2 in the hinge. Undercut D is outside the zone of dangerous loads, so the cross section will not weaken. An additional lateral hole in the undercut D for oil passage can be made instead of axial (not shown) to reduce the likelihood of abrasive (dirt) getting into the contact zone of the spherical heel 9 and the thrust bearing 10 when filling the internal cavity of the hinge with oil and to facilitate this filling with viscous greases.

The limiter sleeve 4 serves to ensure the tightness of the joint in the joint in conjunction with the screw 5 and the cover 7 on the one hand and the housing 1, the seal 6 and the screw 5 on the other, as well as to prevent spontaneous disengagement of the shaft 2 from the housing 1. Moreover, the limiter sleeve 4 should not impede the free rotation (swinging) of the shaft 2 in the spherical support of the heel 9 and the thrust bearing 10.

To this end, the inner hole in the limiter sleeve 4 is made conical, with a cone angle α equal to the maximum angle of swing of the shaft 2.

Rusks 12 and 13 can be made both by turning and by cutting-molding in high-performance stamps from a sheet with at least one (outer) polished surface. Moreover, in the latter case, it is much easier to obtain the outer spherical shape of the desired size with high surface finish. Even technological tightening of the edges of crackers 12 (13) during cutting will not be a defect (in these places, a radius transition is provided between the outer spherical surface and the lateral cylindrical one).

Depending on the thickness of the supporting element (cracker 12 or 13), additional holes / recesses can be used: for example, if the cracker height 12 is less than the resulting gap between the spherical head of the shaft 2 and the housing 1 when the shaft 2 is shifted (tilted) by the maximum swing angle, then the probability of a cracker 12 falling out of its nest and jamming the hinge. To eliminate this situation, a hole is made in the cracker 12, in which an elastomeric spring 14-a is installed, pressing the cracker 12 from the housing 1 into the hole in the shaft 2.

Conversely, with a sufficient thickness of the cracker 13, a recess (blind hole) is made in it to install an elastomeric spring 14-b, which presses the cracker 13 from the hole in the shaft 2 to the housing 1. This option is more preferable since when the outer spherical surface of the cracker is worn 13, it will be gradually pulled out of the hole on the shaft 2. Thus, during operation, in contact between the partial keyway (linear or radial) of the housing 1 and the spherical head of the shaft 2, work is provided with a fresh, unworn lateral edge of the cracker 1 3, what reduces play, heartbeat and vibration.

With a planned repair of the hinge (if the body parts are poorly worn), only crackers 12 (13) and their elastomeric springs 14-a (b) are replaced, which ensures high maintainability. And if the hinge is double (to ensure an equal angle of rotation), then the housing 1 is interchanged to include in the operation of the opposite, slightly worn edges of the partial keyways (linear or radial) in the housing 1 and in the holes of the shaft 2.

Thanks to all the proposed innovations, it was possible to create a hinge for a downhole screw motor with high bearing capacity, long service life, maintainable, technologically cheap to manufacture.

Claims (5)

1. The hinge of a downhole screw motor, comprising a housing with longitudinal grooves, a shaft with a spherical fifth support and a thrust bearing, a limiter sleeve that keeps the shaft from falling out of the housing, and load-bearing elements placed between the housing and the shaft, characterized in that the grooves in the housing are made in the form of segmented linear or radial keyways, and the supporting elements are made in the form of sheet washers or sheet washers with at least one convex spherical surface and a blind or through hole in which An elastomeric spring must be installed. 2. The hinge according to claim 1, characterized in that the hole for refueling is made in the center along the axis of the shaft. 3. The hinge according to claim 1, characterized in that an undercut is made in the spherical shaft head to prevent contact with the enlarged thrust bearing when the shaft is swinging. 4. The hinge according to claim 3, characterized in that a side hole for supplying oil is made in the spherical shaft head. 5. The hinge according to claim 1, characterized in that the internal conical hole is made in the limiter sleeve with a cone angle equal to or greater than the maximum swing angle of the shaft.

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