RU2407877C1 - Downhole motor two-hinge propeller shaft - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: proposed propeller shaft comprises drive and driven hinges each made up of case and half-shaft locked against mutual turn by balls arranged in the case and half-shaft grooves and holes, main and extra annular thrust plain bearings comprising thrust bearings fitted in the case and thrusts coupled with the shaft. Working contact surfaces of said thrusts are spherical. It comprises also flexible boot and case nut to isolate hinge oil-filled cavity. Note here that thrust bearing contact surfaces and those of additional annular bearing thrust represent sphere fragments. Note also that radius of additional bearing sphere exceeds that of the main bearing sphere.

EFFECT: invention using larger-size half-shaft and stronger balls, and fitting additional thrust bearing and additional packing seal on working surface.

2 cl, 2 dwg

Description

The invention relates to component parts of downhole motors for drilling deep wells, namely cardan shafts.

Known double-jointed driveshaft connecting the misaligned driven and driving shafts of a screw pump (see "Screw pumps in the coal industry", K.S. Osipov, Ya.S. Kheifets, Ugleizdat, 1957, p. 42, Fig. 31) including the 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 hinges are connected (rigidly fastened) to each other by a threaded sleeve. To preserve the grease inside the hinges (couplings) and to protect against dirt and water, the cavities of the articulated joints are closed with rubber covers. The disadvantage of this cardan is that each of its hinges has axial play due to the lack of structural elements regulating the position of the half shaft relative to the hinge body.

The cardan shafts according to US patent No. 4,772,246 of 09/20/1988 have the same drawback, in the hinges of which axial clearances between the moment-transmitting elements, the housing and the half shaft are necessary, which leads to their rapid failure during operation, especially in the presence of vibrations.

Also known is US patent No. 4,904,228 of 02.27.1990, p. 18, Fig. 7, according to which an additional thrust bearing is made in the joints of the driveshaft. The disadvantage of this driveshaft is the low resistance of the additional thrust bearing due to the insufficient area of its supporting working surface, insufficient strength of the shaft and torque transmission unit, due to the small size of the spherical sliding surfaces of the additional annular thrust bearing (prototype).

The invention is aimed at eliminating these disadvantages and increasing the resistance of the driveshaft.

This is achieved by the fact that the double-hinged cardan shaft of the downhole motor for connecting the rotor and the spindle shaft of the motor that are misaligned to each other includes drive and driven joints hinged to each other, 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 the grooves of the housing and the holes of the half shaft, the main thrust sliding bearing, comprising a thrust bearing fixed in the recess of the housing and a stop fixed to the half shaft, contacting the surface and the slides 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, an additional thrust sliding bearing, comprising an annular thrust bearing and an annular stop fastened to the half shaft, the contact sliding surfaces of which are also made as fragments of a sphere, a flexible case delimiting together with the nut of the housing, an oil-filled cavity of the hinge, threads for connection to the rotor and spindle shaft of the engine, while the contacting surfaces ltsevyh additional thrust bearing and the abutment of the thrust bearing are made as fragments of spheres, sphere concentric with said main bearing, the radius of the sphere additional bearing greater than the radius sphere main bearing.

In addition, a seal is made on the contacting surfaces of the additional thrust sliding bearing, and the oil-filled hinge cavity between the main thrust and additional thrust sliding bearings is equipped with a movable separation element, for example, a membrane or piston pair, equalizing the hydraulic pressure in this cavity and 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 driveshaft, in which a seal is made on the contacting surfaces of the additional thrust sliding bearing, and an element is made in the body of the housing that equalizes the hydraulic pressure in the joint cavity and the pressure outside it.

The driveshaft comprises a driving hinge 1 (Fig. 1) and a driven hinge 2, each of which contains a housing and a half shaft, namely, housing 3a and half shaft 4a of the driving joint 1, housing 3b and half shaft 4b of the driven joint 2.

A thread 19 is made on the housing 3a of the drive joint 1 for coaxial connection to an engine rotor or to an intermediate transmission element (not shown). A thread 28 is made on the housing of the driven hinge 3b for coaxial connection to the spindle shaft. The half-shafts 4a and 4b of the driving 1 and driven 2 hinges are fastened together, for example, by means of a tapered spline connection 38 or, as an option, can be made as one part.

Each hinge 1 and 2 has a closed oil-filled cavity 15, which is protected from the drilling fluid flow by a seal, for example, a flexible cover 16, a housing nut fixed to the housing 17, and a clamp 18 on the half shaft. Other designs of known seals may be used.

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 conical rollers.

The main hinge 1 and the driven hinge 2 are made of the main thrust bearings, containing thrust bearings 8 fixed in the recess of the housings 3a and 3b and the stops 9 kinematically rigidly fastened to the half-shafts 4a and 4b (By the generalized sign “kinematically rigidly fastened” it is understood that the stops 9 are rigidly fixed, for example, on an interference fit on the shafts 4a and 4b by means of rods 12 or are made integral with them).

In the hinges 1 and 2, additional thrust sliding bearings are made, containing thrust bearings 30 fixed in the housings 3a and 3b, and stops 31 kinematically rigidly fastened to the half-shafts 4a and 4b.

The sliding working surfaces 10 and 32 of the thrust bearings 8 and 30 and the sliding working surfaces 11 and 33 of the stops 9 and 31 in contact with each other, in both hinges - 1 and 2, are made as fragments of spheres, namely, as a spherical hole on the thrust bearing and a spherical segment on the stop .

A distinctive feature of the cardan is that the sliding surfaces 10, 11 of the main bearing and the sliding surfaces 32, 33 of the additional bearing belong to different spheres, the radius R _{2 of the} sphere 34 of the additional thrust bearing is greater than the radius R _{1 of the} sphere 35 of the main thrust bearing, while the centers of the spheres 34 and 35 coincide and are in the plane of 13 centers 14 of the rolling elements 5.

Due to the concentricity of the spheres 34 and 35, the concave spherical working surfaces 10, 32 of the thrust bearings 9, 31 and the convex spherical working surfaces 11, 33 of the stops 9, 31 in contact with them form a kind of stepped hinge (kinematically identical to a conventional ball joint) with the possibility of making the necessary skew the axles of the semi-shafts 4a, 4b and the hulls 3a, 3b of the hinges 1 and 2.

Due to the fact that the radius R _{2 of the} sphere 34 of the additional thrust bearing is larger than the radius R _{1 of the} sphere 35 of the main thrust bearing, the working surface of the additional thrust bearing can be structurally increased in comparison with the prototype. In this case, it becomes possible to optimize the width and contact area of the working spherical surfaces 32, 33 of the additional bearing and their angle of inclination.

In addition, the increased radius R ₂ allows you to increase the inner diameter of the annular thrust bearing 30 and to perform a half shaft of larger diameter, while using larger rolling bodies 5.

In addition, the increase in the annular working surface 33 of the lugs 31 makes it possible to place seals 23 on it (see FIG. 2).

Figure 2 shows the hinge of the cardan, in which on the contact surfaces of the additional thrust sliding bearing, a seal 23 is made, for example, in the form of a rubber ring 3b located in a groove made in the stop 22. An oil-filled cavity 15 of the hinge between the main and additional thrust sliding bearings is provided a separating movable element, for example, a piston pair 37, equalizing the hydraulic pressure in this cavity with the pressure outside it.

A two-joint cardan shaft operates as follows. From the engine rotor, the driveshaft transmits the rotation and the moment of force to the spindle shaft which is not aligned with it and then to the bit. The misalignment of the rotor and the spindle shaft is both linear, caused by the movement of the rotor axis of the single-rotor motor in a circle, and angular, due, for example, to the possible presence of a curve adapter (not shown) between the motor and the spindle (not shown), which is compensated by the misalignment of the axes of the housings 3a, 3b and the drive axle shafts 4a, 4b 1 and follower 2 hinges. The presence in the hinges 1 and 2 of additional sliding bearings, including thrust bearings 30 and stops 31, prevents unwanted excessive slipping (axial movement) of the rolling elements 5 in the grooves 6 and their corresponding additional wear.

In this case, unlike the prototype, the working surfaces 10, 11 and 32, 33 of the main and additional sliding bearings are located on different spheres 35 and 34, however, due to their concentricity, these surfaces form an original step joint, kinematically identical to a conventional ball joint, for due to which the axes of the half-shafts 4a, 4b and the housings 3a, 3b are skewed and the misalignment of the motor rotor and the spindle shaft is compensated.

This feature of the design and operation of the cardan according to the invention allows to increase the resistance of the cardan by increasing the area of the working spherical surfaces 32, 33 of an additional thrust bearing and, as a result, reducing contact stresses in it, using a half-shaft of larger diameter and larger rolling elements of increased strength.

In addition, an increase in the durability of the double-jointed driveshaft is facilitated by the possibility of placing an additional thrust seal bearing on the working surface, which prevents the loss of lubricant in the event of failure of the flexible cover 16.

Claims (2)

1. A double-hinged cardan shaft of the downhole motor for connecting the rotor and the spindle shaft of the motor, which are misaligned to each other, including the drive and driven joints hinged together, 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 the housing and the holes of the half shaft, the main thrust sliding bearing, containing a thrust bearing fixed in the recess of the housing and a stop fixed to the half shaft, contacting sliding working surfaces which are made as fragments of a sphere, the center of which is located in the plane of the centers of the rolling bodies, an additional thrust sliding bearing, comprising an annular thrust bearing and an annular stop fastened to a half shaft, the contact sliding surfaces of which are also made as fragments of a sphere, a flexible cover that delimits together with housing nut, oil-filled cavity of the hinge, threads for connection to the rotor and spindle shaft of the engine, characterized in that the contacting surfaces rotating arm and the abutment of thrust bearing additional thrust bearing are made as fragments of spheres, sphere concentric with the main bearing, the radius of the sphere of radius greater bearing additional main bearing spheres. 2. The double-jointed driveshaft according to claim 1, characterized in that a seal is made on the contact surfaces of the additional thrust sliding bearing and the oil-filled hinge cavity between the main thrust and additional thrust sliding bearings is equipped with a movable separation element, for example, a membrane or piston pair, equalizing hydraulic pressure in this cavity with pressure outside it.

Images