RU2411335C1 - Two-joint drive shaft of bottomhole motor - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: two-joint drive shaft of bottomhole motor, which connects rotor and spindle shaft of motor, which are offset relative to each other, includes drive and driven hinge joints, each of which includes housing and semi-shaft, which are fixed from mutual turn with possibility of misalignment of their axes with rolling elements located in slots and cavities of housing and semi-shaft, thrust bearing including centre pad fixed in the housing and the stop attached to semi-shaft, working sliding surfaces of which have spherical shape, with centre located in plane of centres of rolling element, flexible cover and nut of housing, which restrict oil-filled cavity of hinge joint, thread on the housing of drive hinge joint for attachment to the rotor. At that, semi-shaft of drive hinge joint is attached to the housing of driven hinge joint; semi-shaft of driven hinge joint is outlet element of cardan with thread to be attached to spindle shaft. That is, hinge joints in cardan are located in series and in one direction. In both hinge joints the thrust bearing is located above the plane of centres of rolling elements. Equivalent cardan shafts have reflection symmetric location of hinge joints, which leads to the increase in number of original parts, their unbalance due to bad stream-lining with liquid flow. According to invention, cardan shaft has unidirectional in-series location of hinge joints.

EFFECT: stream-lining of cardan shaft is optimised, parts commonality is improved, service life is extended, its assembly and repair is simplified.

5 cl

Description

The invention relates to component parts of downhole motors for drilling deep wells, and in particular to driveshafts.

A two-joint cardan shaft is known that connects the driven and driving shafts of a screw pump that are misaligned to each other (see Screw pumps in the coal industry, K.S. Osipov, Ya.S. Kheifets, Ugleizdat, 1957, p. 42, Fig. 31), including driven and driving hinges (couplings), each of which contains a body and a half shaft (cylindrical rod) with a ball head at the end abutting against the spherical surface of the cavity of the hinge body (couplings). The torque in each hinge is transmitted through two balls located in the holes (sockets) of the ball heads and the grooves of the hinge body. The semi-shafts (cylindrical rods) of the driven and driving joint are connected (rigidly fastened) to each other by a threaded sleeve. To preserve the grease inside the hinges (couplings) and to protect it from dirt and water, the cavities of the hinge joints are covered with rubber covers (Prototype).

A number of double-hinged cardan shafts of downhole motors are also known (see, for example, US Patent No. 4,772,246 of 09/20/1988, US Patent No. 4,904,228 of 02/27/1990, Fig. 7).

All these two-jointed cardan shafts have a mirror-symmetrical arrangement of the leading and driven hinges (symmetry of the first kind, see the mathematics reference book I.N. Bronstein and others). This arrangement, obviously, seems natural, putting the hinges in the same working conditions and is invariably used in all known structures. However, during the analysis it becomes obvious that such an arrangement of the cardan shaft hinges of the downhole motor puts them in unequal kinematic and hydraulic conditions. The practice of operating cardan shafts has shown that with a mirror-symmetric arrangement of the hinges, in order to avoid loosening and unscrewing, the threaded connection between the housing of the driven hinge and the nut of the housing should have a left thread, while the leading joint should have a right thread, that is, these threaded joints should also be mirror-symmetric, which leads to the interchangeability of the drive and driven joints of the driveshaft, and as a result, to increase the number of original parts in it and complicate the technology propeller shaft assembly. In addition, there is an unevenness of the flexible covers of the leading and driven hinges due to their different flow around the flushing fluid. So, as a result of the attack by the fluid flow of the flexible cover of the driven joint, its strength is violated, which leads to a decrease in the motor resource of the driveshaft as a whole.

The invention is aimed at eliminating these disadvantages. This is achieved by the fact that in the double-hinged cardan shaft of the downhole motor, connecting the rotor and the spindle shaft of the motor, which are misaligned to each other, including the driving and driven hinges, each of which contains a housing and a half shaft, fixed from mutual rotation with the possibility of their axes being skewed by rolling elements located in grooves and holes, respectively, of the housing and the half shaft, a thrust sliding bearing comprising a thrust bearing fixed in the recess of the housing and a half shaft stop, the contact sliding surfaces of which are made as fragments of a sphere, the center of which is located in the plane of the centers of the rolling bodies, a flexible (elastic) cover that delimits, together with the housing nut, the oil-filled joint cavity, thread on the drive joint body for coaxial connection to the motor rotor, thread for attachment to the spindle shaft, half shaft of the drive joint rigidly attached to the housing of the driven hinge, the half shaft of the driven hinge is the output element of the cardan and is threaded for coaxial connection to the spindle shaft, and in both hinges are resistant plain bearing occupies a position above the plane of the centers of the rolling bodies.

In this way, unification of the driving and driven joints is achieved, including in terms of connecting nuts and housings with unidirectional threads that match the direction of rotation of the motor spindle shaft.

Complete unification of the driving and driven joints is ensured by the implementation of the half shaft of the driving joint of two parts: the upper - the half shaft, identical to the half shaft of the driven joint, and the lower - extension shaft.

In addition, in each hinge of the proposed driveshaft, an additional thrust sliding bearing is made, located below the plane of the centers of the rolling bodies, the contacting surfaces of its stop and thrust bearing are made as fragments of a sphere whose radius is greater than the radius of the spherical surfaces of the overlying thrust sliding bearing, and the centers of the spheres of both sliding bearings coincide, and the thrust bearing of the additional sliding bearing is fixed in the housing of each hinge by the housing nut, and the emphasis is made on a half shaft. In addition, a seal is made on the contacting surfaces of the additional thrust sliding bearing, and the oil-filled hinge cavity between the thrust and additional thrust sliding bearings is equipped with a movable separating element, for example, a membrane or lubricator, equalizing the hydraulic pressure in this cavity with the pressure outside it.

Figure 1 shows a longitudinal section of a variant of the proposed propeller shaft according to the invention.

Figure 2 shows the hinge of the cardan, in which an additional thrust sliding bearing is made.

Figure 3 shows a hinge in which a seal is made on the contacting surfaces of an additional thrust sliding bearing.

The driveshaft contains a driving hinge 1 (Fig. 1) and a driven hinge 2, each of which contains a housing and a half shaft, namely, the housing 3a of the driving hinge 1, the shaft 5a of the driving hinge 1, the housing 3b of the driven hinge 2, the shaft 5b of the driven hinge 2. The hulls and half-shafts of the hinges 1 and 2 are fixed from mutual rotation with the possibility of their axes being skewed by the rolling bodies 5 located in the grooves 6 and holes 7 of the bodies 3a, 3b and the half-shafts 4a, 4b, respectively. Rolling bodies can be balls, cylindrical and barrel-shaped rollers. Axial sliding bearings are made in the leading joint 1 and the driven joint 2, comprising thrust bearings 8 fixed in the recess of the housings and kinematically rigidly fixed to the axle shafts 4a and 4b 9. By the generalized sign “kinematically rigidly fixed” it is understood that the stops 9 are rigidly fixed, for example, at an interference fit on the half-shafts or are made integral with the half-shafts. The sliding working surfaces 10 of the thrust bearings 8 and the sliding sliding surfaces 11 of the stops 9 in contact with each other, in both hinges - 1 and 2, are made as fragments of a sphere, for example, as a spherical hole on the thrust bearing and a spherical segment on the stop. The center 12 of these spheres is in the plane 13 of the centers 14 of the rolling bodies 5. Each hinge 1 and 2 has a closed oil-filled cavity 15, protected from the surrounding mud flow by a seal, for example, a flexible cover 16, a housing nut fixed to the housing 17, and a half-shaft clamp 18. You can use other designs known seals. To the housing 3a of the drive joint 1 is kinematically rigidly attached (made at the same time or, for example, connected by an intermediate thread), the thread 19 for coaxial connection to the engine rotor or to the intermediate transmission element (not shown in figure 1). As a structural element, there is also a thread 28 for coaxially connecting to the spindle shaft. Performing it on a slave half shaft 4b is a hallmark of the design. Also a distinctive design feature is that the semi-shaft 4a of the drive joint 1 is kinematically rigidly fastened to the housing 3b of the follower 2. It follows that the main feature is the unidirectional sequential arrangement of the drive and follower hinges, that is, the parts in the drive 1 and follower 2 have the same spatial arrangement and sequence, while in both joints the thrust bearing occupies a position above the plane 13 of the rolling elements 5.

Figure 2 shows a variant of the drive shaft hinge, in which an additional thrust sliding bearing is made, comprising a thrust bearing 21 and a stop 22. Moreover, the main and additional thrust sliding bearings are located on different sides relative to the plane of the centers 13 of the rolling bodies 5. The contact surfaces of the thrust bearing 21 and the stop 22 additional sliding bearings are made as fragments of a sphere 29, the radius of which is greater than the radius of the spherical surfaces 30 of the main thrust bearing, and the centers of the spheres of both bearings slip coincide, the thrust bearing 21, additional thrust sliding bearing in the housing of each hinge, e.g., the nut body 17 and the fence 22 is kinematically rigidly formed Stubshaft 4.

Figure 3 shows a hinge in which a seal 23 is made on the contact surfaces of the additional thrust sliding bearing, for example, in the form of a rubber ring 31 located in a groove made in the stop 22. The oil-filled cavity 15 of the hinge between the main and additional thrust sliding bearings is provided with a spacer a movable element 32, for example a lubricator, equalizing the hydraulic pressure in this cavity with the pressure outside it.

The advantages and features of the two-jointed cardan shaft according to the invention are predetermined by the unidirectional sequential arrangement of the leading 1 and driven 2 hinges. Namely, the kinematics of the operation of both hinges in the proposed universal joint shaft is identical, in contrast to the version with mirror-symmetrically arranged hinges.

In a cardan with a mirror-symmetric arrangement of the hinges, threaded connections between the housing and the housing nut in the master and driven hinges are made in different directions to avoid turning one of the threaded joints, for example, when the rotor rotates clockwise, the right nut is made on the housing nut and the housing of the master joint thread, and on the housing nut and follower housing - left. This is caused by the interaction of the rolling elements with the housing nut.

With a unidirectional sequential arrangement of hinges 1 and 2, these threaded connections 25 and 26 between the housings 3a and 3b of the master and follower hinges 1 and 2 and their nuts 17 (Fig. 1) both work “in turn” if the direction of their screw thread coincides with the direction rotation of the spindle shaft, which allows to unify the leading and driven joints and the universal joint shaft.

In addition, in a double-hinged cardan shaft with a mirror-symmetric arrangement of the hinges, the reliability of the elastic cover of the driven hinge is significantly lower than the leading hinge, due to their different interactions with the flow of flushing fluid. So, if the elastic cover of the drive hinge is protected from the direct impact of the flow of washing liquid containing solid particles by the housing, then in the mirror-symmetric driven hinge, the elastic cover is attacked by washing liquid. Less stability of the elastic cover of the driven joint leads to a decrease in the motor resource of the driveshaft as a whole.

In the proposed cardan with a unidirectional sequential arrangement of hinges 1 and 2, both flexible covers 16 are protected by hinge bodies 3a and 3b from attack by a fluid flow, the direction of which is indicated by arrow 27.

In this case, it is possible to unify the housings 3a and 3b and other hinge elements.

The present invention allows to simplify the design of the driveshaft, to unify the details as much as possible and to increase its service life and maintainability.

Claims (5)

1. A double-hinged cardan shaft of the downhole motor connecting the rotor and the spindle shaft of the motor, which are misaligned to each other, including the driving and driven hinges, each of which contains a housing and a semi-shaft, fixed from mutual rotation with the possibility of their axes being skewed by the rolling bodies located in the grooves and holes, respectively the housing and the half shaft, a thrust sliding bearing, comprising a thrust bearing and a half shaft fixed in the recess of the housing, the contact sliding surfaces of which are made as fragments of a sphere, cent which is located in the plane of the centers of the rolling bodies, a flexible (elastic) cover that delimits, together with the housing nut, an oil-filled joint cavity, thread on the drive joint body for coaxial connection to the motor rotor, thread for connection to the spindle shaft, characterized in that the drive joint half shaft attached to the housing of the driven hinge, and the shaft of the driven hinge is the output element of the propeller shaft and is threaded for coaxial connection to the spindle shaft, and in both hinges the sliding bearing occupies a position above the plane of the centers of the rolling bodies. 2. The double-jointed cardan according to claim 1, characterized in that the half shaft of the drive joint is made of two parts interconnected by a thread: a shaft that is identical to the shaft of the driven joint and an extension shaft. 3. The double-jointed driveshaft according to claim 1, characterized in that the threads connecting the nuts and the housings of the driving and driven hinges are made unidirectional, coinciding with the direction of rotation of the motor spindle shaft. 4. The double-jointed driveshaft according to claim 1 or 2, characterized in that in each hinge there is an additional thrust sliding bearing located below the plane of the centers of the rolling bodies, the contacting surfaces of its stop and thrust bearing are made as fragments of a sphere whose radius is larger than the radius of the spherical surfaces of the overlying thrust bearing, and the centers of the spheres of both sliding bearings coincide, and the thrust bearing of the additional sliding bearing is fixed in the housing of each hinge with a housing nut, and the emphasis olnen shaft. 5. The double-jointed driveshaft according to claim 3, characterized in that a seal is made on the contacting surfaces of the additional thrust sliding bearing and the oil-filled hinge cavity between the thrust and additional thrust sliding bearings is equipped with a movable dividing element, for example, a membrane or lubricator, equalizing the hydraulic pressure in this cavities with pressure outside it.

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