High-Low Speed Rotary Drive Mechanism

Rotary drive apparatus for selectively driving a tool at high torque, low speed and low torque, high speed that is used in making up and breaking out rod joints of, for example, a drill stem.

In the prior art, for example see U.S. Pat. No. 3,625,095 to Barnett et al, it is old to provide power driven pipe tongs for making up and breaking out joints of a drill stem and which are capable of spinning a pipe at high speed, low torque and at low speed, high torque. The Barnett apparatus includes a piston cylinder combination and hydraulic motors to provide the sources of power. However, the construction thereof is relatively complex.

U.S. Pat. No. 3,518,903 to Ham et al discloses a power tong assembly and a dependingly mounted backup tong assembly, the power tong assembly being powered by a hydraulic motor and the backup assembly by a piston cylinder combination. In U.S. Pat. No. 2,019,814 to Holmes et al there is disclosed a chuck having a gear toothed ring intermeshing with a rack that is reciprocated by a piston cylinder combination.

In order to provide a single unit of relatively simple construction that has a constant horsepower producing multitorque and multi-speed output, this invention has been made.

Apparatus for drivingly rotating a driven member that includes a housing, a first ring gear rotatable mounted in the housing, a second ring gear mounted on the first ring gear for rotation relative thereto, a rack powered by a piston cylinder combination to drivingly rotate the second ring gear, a hydraulic motor to drivingly rotate the first ring gear and an overriding ratchet assembly mounted by one of the ring gears for transmitting a rotary driving force in one angular direction from the one ring gear to the other when the one ring gear is drivingly rotated in one direction and permit the other ring gear being drivingly rotated relative the one ring gear in said one angular direction.

One of the objects of this invention is to provide a new and novel means for initially developing a high torque in a driven member for initial rod joint breaking and making with a low speed and then a low torque at a high speed. Another object of this invention is to provide a rotary drive mechanism having a high speed, low torque first power operated ring gear and a low speed, high torque second power operated ring gear, new and novel means for providing a smooth interface between the two modes of drive. A further object of this invention is to provide a new and novel hollow spindle spline type drive permitting free axial movement of the driven member and alternately providing a high speed, low torque and a low speed, high torque drive to the driven member.

FIG. 1 is a plan view of the apparatus of this invention with parts thereof broken away to show other structural features, said view being generally taken along the line and in the direction of the arrows 1--1 of FIG. 2 and showing elements that are to be driven thereby in cross section;

FIG. 2 is a cross sectional view generally taken along the line and in the direction of the arrows 2--2 of FIG. 1, said view also in part diagrammatically showing a tool to be driven in dotted lines;

FIG. 3 is a fragmentary cross sectional view generally taken along the line and in the direction of the arrows 3--3 of FIG. 2 to more clearly illustrate the ratchet assembly and the mounting thereof; and

FIG. 4 is a fragmentary plan view with the housing closure plug removed to show the ratchet assembly.

The high-low speed rotary drive mechanism, generally designated 10, includes a housing, generally designated 11. The housing 11 includes a removable top closure 12, a bottom wall 13, a side wall 14, and an end wall 15. Axially aligned apertures 18 are provided in the closure and bottom wall to mount other structure to be described and for having a drill rod extended therethrough. Mounting bars 163 are secured to the bottom wall on opposite sides of the bottom wall aperture, the mounting bars being secured to legs or arms 17 which may be secured to the clamp apparatus described in co-pending application Ser. No. 48,488 or co-pending application Ser. No. 48,489. It should be understood that the housing may be mounted in a conventional manner on other structure used in drilling.

Bearings 22 are provided in the axially aligned apertures in the closure and bottom wall 13 for mounting the tubular spindle 21 for rotation about a central axis A--A that would be coextensive with the axis of a drill rod extended through the axially aligned apertures of the closure and housing bottom wall. A pair of arcuate lugs 23 are welded or integrally formed with the inner peripheral wall of the spindle while a ring 24 is fixedly attached to the inner periphery of lugs. The axial height of the ring 24 is substantially less than the axial height of the spindle and is located near the lower end of the spindle. The spindle, lugs 23 and ring 24 bound a pair of diametrically opposite spaces 25 in which the driven elements 26 or other parts of the tool 27 to be driven are extended.

A main drive ring gear 30 is fixedly secured to the spindle 21 for driving the spindle, the drive gear extending radially outwardly of the spindle. The gear teeth of the drive gear 30 are in intermeshing relationship with those of the pinion gear 31 which is keyed to the shaft 32 of a reversible hydraulic motor 33 to be driven thereby. As may be noted from FIG. 2, the hydraulic motor is removably secured to the housing bottom wall with its shaft extending into the housing.

An upper ring gear 36 is mounted on the spindle for rotation relative thereto and is axially located between closure 12 and the lower gear 30. Cylinder 40 is fixably attached to housing end wall 15 and has a piston rod extended into the housing for reciprocating an elongated gear rack 37. The teeth of rack 37 are in intermeshing relationship with the teeth of the upper ring gear 36, a cut out 38 being provided in housing wall 14 and having the rack extended thereinto to retain the rack teeth in intermeshing relationship with the upper gear teeth as the rack is reciprocated.

For transmitting a driving force in one angular direction from gear 36 to gear 30 while permitting rotation of gear 36 relative to gear 30 in the opposite angular direction, without driving gear 30, there is provided a ratchet assembly, generally designated 44. The ratchet assembly includes an annular housing 46 that is pressed into a vertical aperture that extends through gear 36. The central axis of the ratched housing is radially spaced from and parallel to axis A--A. Axially reciprocally mounted in the ratchet housing is a ratchet member (plunger) 49 having a pawl portion 49a of a diameter to be extended into one of the apertures 45 formed in the main drive gear when an aperture 45 is axially aligned with the pawl portion. It is to be noted that the pawl portion has an inclined planar surface 49b that extends axially outwardly of the lower end of the main body portion 49c of the ratchet member so that as the gear 30 is driven angularly in one direction (arrow 63) relative to gear 36 the ratchet member is cammed out of the vertical aperture 45 (moved in direction of arrow 56) to permit the ring gear 30 rotating in one direction relative gear 36. However, if the gear 36 is being driven in the same angular direction at a higher speed than gear 30 (or gear 30 stationary), the pawl in extending into aperture 45 will drive gear 30 to rotate with gear 36. In this connection it is to be noted, there is provided a spring 50 having one end abutting against the ratchet member for resiliently urging it into an aperture 45, the opposite end of the spring bearing against washer 51 which in turn abuts against a downwardly facing annular shoulder 52 of the ratchet housing. To limit the downward movement of the plunger 49 (direction opposite arrow 56), the main body portion 49c thereof has an outer diameter larger than that of an aperture 45 so that when the pawl portion 49a extends into an aperture 45, the main body portion abuts against the top surface of ring gear 30. Surface 49b intersects with the lower surface of main body portion 49c, i.e. the pawl being of a cylindrical shape that is cut off along an inclined plane to provide the planar camming surface 49b.

To permit gear 30 being driven in the opposite angular direction (arrow 64) relative to gear 36 and alternately to permit gear 36 driving gear 30 in said opposite angular direction, the ratchet member is rotatable about its vertical axis angularly through 180 degrees relative to the ratchet housing. To retain the ratchet member in the selected one of its rotated positions, with the upper reduced diameter portion 49d thereof extended upwardly through washer 51, a pin 53 is extended through portion 49d into upwardly opening notches 47, 48 in the upper axial end of the ratchet housing.

Each notch is formed by a vertical (axial) wall 47 and an inclined wall 48, that is tapered axially downwardly toward the respective wall 47, the opposite ends of the pin extending into the apex portions of the notches when pawl portion 49a is extended into an aperture 45. However, when the pawl is cammed out of an aperture 45 the pin 53 is still axially below the top ends of walls 47 of the housing 46 and accordingly the ratchet member cannot rotate about its axis out of the position it is set in to a position surface 49b is 180.degree. opposite its present position. When the ratchet member is cammed out of an aperture 45 the pin 53 can be manually grasped (or with an appropriate tool) and rotated about the ratchet member axis 180.degree. degrees to the second of the ratchet member angular positions relative the gear 36. To facilitate rotating the ratchet member there is provided a removal plug 55 in aperture 12a of the closure 12 such as shown in FIG. 3.

The structure of this invention having been described, the use thereof will now be set forth. The hollow spindle 21 is rotated in a clockwise direction (arrow 63) as viewed from the top for screwing together threaded rod joints and conversely rotated in a counterclockwise direction (arrow 64) when unthreading joints. The driving torque is transmitted by lugs 25 to and through elements 26 to the jaw mechanism (not shown) of tool 27. Assuming the rod joints are to be threaded together, initially only a low torque is required and accordingly oil is ported to the hydraulic motor 33 to drive it in an appropriate direction so that gear 31 drives the ring gear 30 in the direction of the arrow 63. At this time the ratchet member 49 is set such that the part of the pawl portion that extends furthest axially remote from the main body portion 49c is located in a clockwise direction relative the remainder of the pawl portion. Accordingly, as long as the torque required to rotate the drive spindle is not too high, the hydraulic motor will cause the gear 30 to be rotated in a clockwise direction relative to gear 36. This relative rotation results in the ratchet member being continually cammed out of the apertures 45 of gear 30. However, once the torque requirements are greater than that provided by the hydraulic motor 33, fluid under pressure is applied to the one end of cylinder for reciprocating the rack 37 from a position to the left of that shown in FIG. 1 to the FIG. 1 position. This results in gear 36 being rotated in the direction of the arrow 63 relative to the now stationary gear 30 and as soon as the ratchet member is axially aligned with one of the apertures 45, the pawl portion thereof is resiliently urged into the aperture 45 for transmitting the driving force from the pawl portion to gear 30. Now gear 30 is rotated with gear 36 until the end of the stroke of the piston rod in the direction of the arrow 65. In the event the drill rod joint is still not sufficiently threaded, fluid under pressure is applied to the opposite end of the cylinder for moving the rack in the direction opposite the arrow 65. This results in the gear 36 being rotated in the direction of the arrow 64. Since the rotational force applied to the gear 36 is opposite that being provided to gear 30 by the hydraulic motor, the ratchet member is cammed out of aperture 45 (moved in the direction of the arrow 56), and gear 36 continues to rotate in the direction of the arrow 64. It is to be noted that due to the inclination of the surface 49, as the ratchet member moves axially in alignment with each of the adjacent aperture 45, it is cammed out of the respective aperture 45 in the manner previously indicated. At the end of the piston stroke, fluid is again applied to the one end of the cylinder for moving the rack in the direction of the arrow 65 for rotating gear 36 in the direction of arrow 63 and through the ratchet member rotate gear 30 in the same direction in the manner previously indicated.

Now in the event the spindle is to be rotated in the direction of arrow 64, the upper gear 36 is rotated to a position the ratchet assembly is below plug 55, and with plug 55 removed, the ratchet member is rotated 180.degree. about its axis as previously indicated. Now the axially elongated part of the pawl portion 49a would bear against the counterclockwise portion of an aperture 45 when extended thereinto. Accordingly, when gear 30 is not rotating and the rack is to be removed in a direction opposite arrow 65 gear 36 would drive gear 30 in the direction of arrow 64. Further, when the rack is moved in the direction of the arrow 65, the gear 36 would be rotated in the direction of the arrow 63 whereby the ratchet member is cammed out of aperture 45, and accordingly the main drive gear 30 is not rotated.

Through the use of the apparatus of this invention the rack and piston cylinder combination provide a high torque with limited travel while the hydraulic motor provides a low torque, high speed for threading and unthreading rod joints. Additionally, the overiding ratchet assembly provides a smooth interface between the operating mode of high speed, low torque, and low speed, high torque for each angular drive direction. Additionally, through the provision of the arcuate spaces 25, the drive elements 26 for the tool 27 can move axially with the driven drill rod while the drive is being imparted thereto by the drive lugs 23 of the apparatus of this invention for rotating the drive elements 26 about the axis A--A. That is the drive elements 26 are axially movable relative the lugs 23, but cannot rotate relative lugs 23 as long as the drive elements extend to a lower elevation than the top of lugs 23.