Ball transfer mechanism with polycrystalline diamond bearing support

Abstract

A ball transfer mechanism for a harmonic drive and linear piston motor is disclosed. The ball transfer mechanism includes a spherical ball and a cylindrical seat portion. The seat portion defines a hemispherical shaped recess with a contour for receiving the ball. The ball transfer mechanism is in an exterior wall of a housing for converting rotary motion to linear motion, driving a linear piston motor. The harmonic drive drives a rotor of the linear piston motor. The harmonic drive includes a hollow cylindrical coupler portion engaging a rotor portion for transferring torque to the rotor portion. Transfer mechanisms disposed along a housing wall of the linear piston motor engage the coupler portion. The coupler portion includes harmonic cam grooves for receiving spherical balls in the ball transfer mechanism that drives rotational motion in the rotor in response to axially linear movement of the piston assembly.

Claims

1. A ball transfer mechanism comprising: a plurality of spherical balls and corresponding cylindrical seat portions of a hollow cylindrical housing; the corresponding seat portions defining a hemispherical recess with a contour for receiving the plurality of spherical balls; the ball transfer mechanism disposed within an exterior wall of the hollow cylindrical housing for converting rotary motion to linear motion for driving a linear piston motor disposed within the housing; wherein the mechanism further comprises retainers for the hollow cylindrical housing that are preloaded to enable bi-directional cycling of the linear piston motor; and wherein the seat portion comprises a hard metal outer layer and a polycrystalline diamond core portion.

2. The mechanism of claim 1, wherein the plurality of balls comprises a hard metal or ceramic material.

3. The mechanism of claim 1, wherein the hard metal outer layer is tungsten carbide.

4. The mechanism of claim 1, wherein the plurality of balls comprise steel.

5. The mechanism of claim 1, wherein the seat portion is configured for maximum hardness and wear suitable to withstand extreme heat and pressure associated with a downhole drill motor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The application will become more fully understood from the following detailed description, taken in conjunction with the accompanying figures, wherein like reference numerals refer to like elements, in which:

(2) FIG. 1 shows a cross-sectional view of an exemplary fluid powered linear piston motor of the present invention.

(3) FIG. 2 shows a cross-sectional detail of a drive member with a ball transfer member.

(4) FIG. 3 shows an exemplary PCD bearing ball transfer member.

(5) FIG. 4 shows a spherical bearing constructed of individual polycrystalline diamond inserts used to support the ball in the transfer member.

DETAILED DESCRIPTION OF THE INVENTION

(6) Before turning to the figures which illustrate the exemplary embodiments in detail, it should be understood that the application is not limited to the details or methodology set forth in the following description or illustrated in the figures. It should also be understood that the phraseology and terminology employed herein is for the purpose of description only and should not be regarded as limiting.

(7) Referring to FIG. 1, a fluid powered linear motor 100 is shown. A rotor 14 is axially positioned within an exterior housing 20 with pistons 22 in sealed engagement with inner housing wall 24 for applying hydraulic pressure in a linear direction of flow. Harmonic drive 10 includes a hollow cylindrical coupler 30 with an internal splined surface (not shown), for engagement with splines 16, and for transferring torque to rotor 14. Coupling 30 includes harmonic cam grooves 26 having semicircular cross sections for receiving spherical balls 28 (see FIG. 2, inset). Drive ball retainers 52 are installed over cylindrical coupler 30 with openings that match axial location of harmonic cam grooves 26 to receive installation of ball transfer assemblies (See FIG. 3). A ring 50 with an external splined surface for reacting torque to the housing 20 is installed concentric with the drive ball retainers 52 and mated with pistons 22 and drive ball retainer nut and spring 32 at its ends. The drive ball retainers 52 comprising first and second harmonic drive tracks 12, 14 are preloaded to enable bi-directional cycling of the piston 22 and ring assembly 50 and introduction of torque to the rotor 14 via rotation of the harmonic drive 30.

(8) A pressure chamber 34 is formed between piston 22 and cylinder wall 24. A pressurized fluid 17 may enter the pressure chamber and be available to be discharged outside of the rotor housing through pressure ports and collected through exhaust ports into an exhaust chamber to be exhausted from the rotor housing 18.

(9) FIG. 1 shows a modular assembly for the linear piston motor 100 according to an embodiment of the disclosure. The module assemblies 70 convert a piston action into a rotary motion; an adjacent serial & clocked module (not shown) may be used to generate continuous rotational motion in an output rotor 14 while the piston comprising module 70 is reversing its motion. The module assembly 100 may include a cylindrical coupler 30, a piston assembly 22, a first ball transfer member 12 and a second ball transfer member 14. Reciprocation of the ring assembly 50 directly rotates cylindrical coupler 30 through engagement with ball transfer members 12,14. The ring assembly 50 is disposed upon the cylindrical coupler 30 such that the cylindrical coupler 30 may freely rotate within the motor housing 20. Balls 28 roll within channels 26 while maintaining a fixed linear position within ball transfer member 12, 14, as further described below.

(10) Referring next to FIG. 3, ball 28 may preferable be made of a hard material, e.g., tungsten carbide, steel or similar metal or ceramic balls. In an embodiment the seat portion 36 may be a cylindrical blank having a tungsten carbide outer layer 38 and a polycrystalline diamond, or PCD, core 42 for maximum hardness and wear suitable for the extreme heat and pressure associated with the downhole drill motor. Seat portion includes a hemispherical recess 44 with a contour for receiving ball 28.

(11) In one embodiment, the ball transfer unit 36 may be made from PCD dies, wherein the PCD is a synthetic material produced by sintering diamond powder in the presence of a metal catalyst under extreme heat and pressure to fuse the diamond particles together. With a diamond seat 42, 44, the ball rotates easily with reduced friction. In an alternate embodiment, a spherical bearing 60 constructed of individual polycrystalline diamond inserts 62 (See FIG. 4) may be used to support the ball 28.

(12) While the exemplary embodiments illustrated in the figures and described herein are presently preferred, it should be understood that these embodiments are offered by way of example only. Accordingly, the present application is not limited to a particular embodiment, but extends to various modifications that nevertheless fall within the scope of the appended claims. The order or sequence of any processes or method steps may be varied or re-sequenced according to alternative embodiments.

(13) It is important to note that the construction and arrangement of the ball transfer with PCD bearing support, as shown in the various exemplary embodiments is illustrative only. Although only a few embodiments have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited in the claims. For example, elements shown as integrally formed may be constructed of multiple parts or elements, the position of elements may be reversed or otherwise varied, and the nature or number of discrete elements or positions may be altered or varied. Accordingly, all such modifications are intended to be included within the scope of the present application. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. In the claims, any means-plus-function clause is intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the exemplary embodiments without departing from the scope of the present application.