Abstract:
A wrench assembly including a drive head and an attached socket for engaging a bolt or nut. When the drive head turns, the socket and any engaged threaded member will also rotate. A hydraulic motor and cylinder are also included. The hydraulic motor and cylinder rotate the drive head and socket independently of each other. Typically, the hydraulic motor will rotate the drive head faster than the cylinder but at lower torques. Thus, the hydraulic motor will spin the threaded member down until it is snug, and then the hydraulic cylinder will tighten the threaded member to the desired torque. Alternatively, the hydraulic cylinder may break the threaded member out when it is tight. The hydraulic motor will then spin the loosened threaded member out. Finally, the wrench assembly includes a hydraulic fluid distribution system, including one or more valves that regulate hydraulic fluid flow through the wrench assembly.

Description:
BENEFIT OF PROVISIONAL APPLICATION 
     This application claims benefit of provisional application No. 60/201,434, which was filed on May 3, 2000, and which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to valves in general, hydraulic valves in particular, and especially to a control valve for a hydraulic torque wrench with a hydraulic spin down motor. 
     2. Prior Art 
     The use of hydraulic wrenches to tighten (make up) or loosen (break out) nuts or bolts in high torque applications, such as the erection of off shore risers is well known. See, e.g., U.S. Pat. No. 4,448,096, which is hereby incorporated by reference. These wrenches are well suited to the task of supplying the high torques needed in these applications, however, they are very slow in turning the bolt or nut being tightened or loosened. This is not a problem when the nut or bolt is snug, as very little additional rotation (≲1 full rotation) is all that is usually required to either reach the desired torque or to loosen the nut/bolt to the point that the high torque wrench is no longer needed to turn the nut/bolt. However, when the nut or bolt is not snug, the hydraulic torque wrench can be painfully slow. In the prior art, hydraulic torque wrenches were frequently removed after the bolt/nut was loosened and a low torque spin down wrench would then be used to back the bolt/nut out. Similarly, the low torque spin down wrench might be used to spin the bolt/nut down until it was snug, and then the hydraulic torque wrench would be used to fully tighten the bolt/nut. These wrenches are typically quite large, and changing them out constantly during a job can be expensive and time consuming. In response to these inconveniences, hydraulic torque wrenches that included a self-contained spin down motor were developed. See, e.g., U.S. patent application Ser. No. 09/302,836, which is hereby incorporated by reference in its entirety. However, the prior art combined wrenches, such as that disclosed in PCT/US94/14715, had numerous problems. Some of the problems included complicated and expensive hydraulic controls, troublesome back pressure valves, and an inability to use hydraulic sources already in place, such as the drilling rig hydraulic lines. Accordingly, a hydraulic control system that meets the following objects is desired. 
     OBJECTS OF THE INVENTION 
     It is an object of the invention to provide a control system for a combination hydraulic torque wrench and spin down motor. 
     It is an object of the invention to provide a control system for a combination hydraulic torque wrench and spin down motor which will only run the spin down motor when the hydraulic torque wrench is retracted. 
     It is an object of the invention to provide a control system for a combination hydraulic torque wrench and spin down motor that will only extend the hydraulic torque wrench when the spin down motor is off. 
     It is an object of the invention to provide a control system for a combination hydraulic torque wrench and spin down motor that does not require a back pressure valve. 
     It is an object of the invention to provide a control system for a combination hydraulic wrench and spin down motor that will operate on rig hydraulics. 
     It is an object of the invention to provide a control system for a combination hydraulic torque wrench and spin down motor that does not require a control console separate from the wrench. 
     SUMMARY OF THE INVENTION 
     The invention is intended for use with a hydraulic torque wrench having a built in run down motor. The hydraulic torque wrench essentially comprises a drive head having a socket configured to engage a threaded member such as a bolt or a nut. The drive head has a plurality of ratchet teeth radially positioned on the drive head. A hydraulic cylinder is configured to extend and retract a drive pawl which engages the ratchet teeth upon extension and thus rotates the drive head. Rotation of the drive head results in the rotation of the socket and the threaded member which the socket has engaged. Very high pressures can be exerted against the drive head with the hydraulic cylinder, resulting in torques in the range of about 10,000 to upward of 34,000 ft. lbs. being applied to the threaded member being tightened or loosened. Examples of this type of torque wrench can be found in U.S. Pat. No. 4,448,096. 
     The spin down motor is also preferably hydraulically driven. It is mechanically coupled to the drive head. Although the spin down motor is not configured to generate the very high torques that the hydraulic cylinder is designed to create, it is capable of rotating the drive head much faster than the hydraulic cylinder. In the preferred embodiment, the hydraulic spin down motor will typically generate about 500 ft lbs. of torque and rotate the drive head at about 585 rotations per minute (rpm&#39;s). Torque from spin down motor may be improved, at the price of speed, by adding pulleys or gears as disclosed in U.S. application Ser. No. 09/302,836. The spin down motor is used to either spin the threaded member into a snug position during make up or to spin the threaded member until it is nearly or fully disengaged during break out. Examples of torque wrench assemblies incorporating hydraulic spin down motors may be found in U.S. patent application Ser. No. 09/302,836 and in PCT/US94/14715. 
     The valve of the present invention is configured to operate both the hydraulic torque wrench and the hydraulic spin down motor. It operates on a hydraulic system having pressurized line and a tank line. The pressurized line carries hydraulic fluid coming from the pump while the tank line returns the hydraulic fluid to the system reservoir. These lines enter the distribution block that houses the valve mechanism. They pass through a three position operator valve which controls how hydraulic fluid is directed through the combined wrench assembly. 
     The operator valve has three positions. In its center position, position A, the hydraulic fluid flow to the rundown motor is cut off as is the flow to the extension side of the hydraulic cylinder, while the retraction side is pressurized. In the left position, position B, the rundown motor is pressurized as is the retraction side of the hydraulic cylinder, while the extension side remains cut off from pressure. In the right position, position C, the retraction side is cut off from hydraulic pressure as is the rundown motor, while the extension side of the of the hydraulic cylinder is pressurized. The operator valve is preferably biased with a spring or other means to return to center position A when released by the operator. The preferred mechanisms for routing the hydraulic fluid through the distribution block to achieve the results described above is set forth in the detailed description of the preferred embodiment below. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES 
     FIG. 1 is a perspective view of a preferred embodiment of the wrench assembly engaged with a riser. 
     FIG. 2 is a top view and partial cut-away of a preferred embodiment of the wrench assembly. 
     FIG. 3 is schematic drawing of the hydraulics of a preferred embodiment of the invention using a single four way pilot valve. 
     FIG. 4 is schematic drawing of the hydraulics of a preferred embodiment of the invention using two three way pilot valves. 
     FIG. 5 is an exploded view of one preferred embodiment of a hydraulic wrench suitable for use with the hydraulic control valve disclosed herein. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Hydraulic wrench assembly  1  comprises a drive head  2  having a socket  3  configured to engage a threaded member  4 , such as a nut or a bolt. Drive head  2  also comprises a plurality of ratchet teeth  5  radially positioned on drive head  2 . Hydraulic wrench assembly  1  further comprises a hydraulic cylinder  6 . Hydraulic cylinder  6  is configured to extend and retract a pawl  8  which is positioned to engage ratchet teeth  5  upon extension of pawl  8 . When pawl  8  engages ratchet teeth  5 , drive head  2 , socket  3 , and threaded member  4  may be rotated upon further extension of pawl  8 , which will either tighten or loosen threaded member  4  depending upon the direction of rotation of drive head  2 . Pawl  8  may retracted and extended again, further rotating drive head  3 , socket  3 , and threaded member  4  until the desired torque is reached or until threaded member  4  is adequately loosened. 
     Hydraulic wrench assembly  1  further comprises a spin down motor  9  which is preferably hydraulically driven and should be mechanically coupled to drive head  2  so that operation of spin down motor  9  will result in drive head  2 , socket  3 , and threaded member  4  being rotated. Typically, spin down motor  9  will rotate at about 585 rpm and will be configured to provide about 500 ft lbs of torque to threaded member  4 . Spin down motor  9  will be used until threaded member  4  is snug, a condition that will be apparent when spin down motor  9  and drive head  2  stop turning. 
     Spin down motor  9  will stop turning when it “torques out.” Hydraulic spin down motor  9  acts as blockage in the hydraulic line feeding it. As the pressure builds up, the pressurized fluid causes motor  9  to rotate which allows the fluid to pass and prevents the pressure from building up further. However, if something prevents motor  9  from rotating, the pressure will continue to increase until either that obstacle is overcome and motor  9  rotates allowing some of the fluid to pass or until relief is obtained elsewhere. As threaded member  4  gets tighter, it will obviously provide more and more resistance to the rotation of motor  9 . Thus, as threaded member  4  gets tighter and tighter, the pressure in the hydraulic line will be forced ever higher. Relief is provided by motor torque control valve  10 , which is set to open a predetermined pressure. When the pressure in the hydraulic line reaches a preset level, motor torque control valve  10  will open and allow the hydraulic fluid to flow to tank, avoiding motor  9 . When this happens, motor  9  will stop turning. The torque exerted by motor  9  when the hydraulic pressure is sufficient to cause motor torque control valve  10  to open is the maximum torque that will be exerted by motor  9  with motor torque valve  10  in place. It is at this point that motor  9  is said to “torque out.” Additional tightening must be performed with hydraulic cylinder  6 . 
     The maximum torque exerted by hydraulic cylinder  6  is controlled by a cylinder torque control valve  11  in much the same way that the torque exerted by motor  9  is controlled by motor torque control valve  10 . Cylinder  6  acts as a blockage in the hydraulic line feeding it. The pressure in the line and in cylinder  6  will increase until piston  12  moves, increasing the volume of cylinder  6  and relieving the pressure. When cylinder  6  is extending pawl  8  against ratchet teeth  5  to turn drive head  2  and threaded member  4 , threaded member  4  will resist the extension of cylinder  6 . When this happens, the pressure in the hydraulic line and in cylinder  6  will continue to increase until sufficient torque is generated to overcome the resistance of threaded member  4 , at which point drive head  4  and threaded member  4  will be rotated, further tightening threaded member  4  and increasing the torque needed to tighten threaded member  4  further. As this continues, the pressure in the hydraulic line will continue to increase until the pressure is sufficient to open cylinder torque control valve  11 . When this happens, piston  12  of cylinder  6  can be extended no further, and cylinder  6  is said to have “torqued out.” 
     The torque exerted by motor  9  and cylinder  6  for each pound per square inch of pressure in the hydraulic lines can be calibrated. These figures will vary with individual hydraulic components, and should be readily obtainable from the manufacturer of the part. Once it is known, the maximum torque exerted by either component of wrench assembly  1  may set by the operator simply by adjusting the pressure at which motor torque control valve  10  or cylinder torque control valve  11  will open. 
     The speed of motor  9  or cylinder  6  may be controlled by a motor speed control valve  13  or a cylinder speed control valve  14 . Both valves  13  and  14  operate by restricting the rate at which fluid flows through the hydraulic lines to motor  9  or cylinder  6 . This will prevent cylinder  6  or motor  9  from extending, retracting or rotating too fast, which could lead to operator injury or to equipment damage. Speed control valves  13  and  14  should preferably be positioned downstream from motor torque control valve  10  or cylinder torque control valve  11 , respectively. 
     The operation of wrench assembly  1  is controlled by a distribution block  7  from a three position operator control valve  15 . Operator control valve  15  has a center position A in which motor  9  and the extension side  16  of cylinder  6  are not pressurized and are connected to the tank and in which retraction side  17  of cylinder  6  is pressurized. Operator control valve  15  is preferably spring biased to return to center position A when it is released. Operator control valve  15  also has a left position B in which motor  9  and retraction side  17  of cylinder  6  are pressurized, and extension side  16  of cylinder  6  is connected to the tank. Finally, operator control valve  15  has a right position C in which extension side  16  of cylinder  6  is pressurized and retraction side  17  and motor  9  are connected to the tank. 
     Distribution block  7  preferably contains a pressure line  18  and a tank line  19 . Pressure line  18  preferably has motor branch  18 A and a cylinder branch  18 B. Motor branch  18 A of pressure line  18  runs into operator control valve  15 . When operator control valve  15  is in left position B, motor branch  18 A is connected to motor hydraulic line  20  which contains motor torque control valve  10  and motor speed control valve  13 . Motor hydraulic line  20  provides hydraulic fluid and pressure to motor  9 , causing motor  9  to run. Motor tank line  21  allows hydraulic fluid to flow out of motor  9  to tank line  19 . When operator control valve  15  is in either center position A or right position C, motor hydraulic line  20  is connected to tank line  19 . Thus, when operator control valve  15  is in either position A or C, motor  9  will not run. 
     In one preferred embodiment, a pilot valve line  22  extends from operator control valve  15  to pilot valve  23 . Additionally, cylinder branch  18 B of pressure line  18  runs directly to pilot valve  23  without running through operational control valve  15 . Pilot valve  23  has a first position D and a second position E. Pilot valve is preferably biased with a spring or other means into first position D. 
     A cylinder retraction line  24  and a cylinder extension line  25  extend from pilot valve  23  to retraction side  17  and extension side  16  of cylinder  6 , respectively. When pilot valve  23  is in first position D, pilot valve  23  connects extension line  25  with cylinder tank line  26  which is connected to tank line  19 . Pilot valve  23  also connects cylinder branch  18 B of pressure line  18 , which preferably contains cylinder torque control valve  11  and cylinder speed control valve  14 , with cylinder retraction line  24 , when pilot valve  23  is in first position D. Thus, when pilot valve  23  is in first position D, retraction side  17  of cylinder  6  is pressurized and extension side  16  is connected to the tank. 
     When pilot valve  23  is in second position E, pilot valve  23  connects extension line  25  with cylinder branch  18 B of pressure line  18  and retraction line  24  with cylinder tank line  26 . Thus, when pilot valve  23  is in second position E, extension side  17  is pressurized and retraction side  16  is connected to the tank. 
     As stated above, pilot valve  23  is preferably spring biased into first position D. When pilot valve line  22  is pressurized it will exert pressure against pilot valve  23  and, overriding the spring biasing, will move pilot valve  23  into second position E. 
     When operational control valve  15  is in center position A or left position B, pilot valve line  22  will be connected to tank line  19 . Thus, when operational control valve  15  is in either center position A or left position B, pilot valve line  22  will not be under pressure and pilot valve  23  will be in first position D. However, when operational control valve  15  is in right position C, pilot valve line  22  will be pressurized and pilot valve  23  will move into second position E. This will pressurize extension side  16  and connect retraction side  17  to tank line  19 , causing piston  12  and pawl  8  to be extended. 
     In the embodiment described above, pilot valve  23  is a four way directional control valve. However, in another embodiment, principally for use when space is at a premium, pilot valve  23  may be a pair of three way directional control valves  23 A and  23 B. In this embodiment, pilot valve line  22  will have a retraction branch  27  and an extension branch  28 . Retraction branch  27  will connect pilot valve line  22  to pilot valve  23 A and extension branch  28  will connect pilot valve line  22  to pilot valve  23 B. Additionally, cylinder branch  18 B of pressure line  18 , will have an extension branch  18 C and a retraction branch  18 D. Extension branch  18 C extends from cylinder branch  18 B to pilot valve  23 B and retraction branch  18 D extends from cylinder branch  18 B to pilot valve  23 A. Pilot valve  23 A is connected to retraction side  17  of cylinder  6  by cylinder retraction line  24 , and pilot valve  23 B is connected to extension side  16  of cylinder  6  by cylinder extension line  25 . Pilot valves  23 A and  23 B control whether extension side  16  or retraction side  17  is pressurized. 
     Pilot valves  23 A has a first position L and a second position M. Pilot valve  23 A is preferably spring biased to remain in first position L. When pilot valve  23 A is in first position L, pilot valve  23 A will connect retraction line  24  to retraction branch  18 D of pressure line  18 . Thus, when pilot valve  23 A is in first position L, retraction side  17  of cylinder  6  will be pressurized and piston  12  will be retracted. 
     When pilot valve  23  is in second position M, pilot valve  23 A will connect retraction line  24  to tank line  19 . Thus, when pilot valve  23 A is in second position M, retraction side  17  of cylinder  6  will not be pressurized and piston  12  will be free to extend. 
     Pilot valve  23 B also has a first position N and a second position O. Pilot valve  23 B is preferably spring biased to remain in first position N. When pilot valve  23 B is in first position N, pilot valve  23 B will connect extension line  25  to tank line  19 . Thus, when pilot valve  23 B is in first position N, extension side  16  of cylinder  6  will not be pressurized and piston  12  will be free to retract. 
     When pilot valve  23 B is in second position O, pilot valve  23 B will connect cylinder extension line  25  to extension branch  18 C of pressure line  18 . Thus, when pilot valve  23 B is in second position O, extension side  16  of cylinder  6  will be pressurized and piston  12  will extend. 
     When operator control valve  15  is in center position A or left position B, operator control valve  15  will connect pilot valve line  22 , its retraction branch  27 , and its extension branch  28  to tank line  19 . Thus, when operational control valve  15  is in either center position A or left position B, neither pilot valve line  22  nor its retraction and extension branches  27  and  28  will be under pressure, and pilot valves  23 A and  23 B will be in first positions L and N. However, when operational control valve  15  is in right position C, pilot valve line  22 , it retraction branch  27  and its extension branch  28  will be pressurized and pilot valves  23 A and  23 B will move into second positions M and O. Thus, when operational control valve  15  is in right position C, pilot valve  23 A will connect retraction line  24  to tank line  19 , and pilot valve  23 B will connect cylinder extension line  25  to extension branch  18 C of pressure line  18 . Therefore, when operational control valve  15  is in right position C, retraction side  17  of cylinder  6  will not be pressurized and extension side  16  of cylinder  6  will be pressurized, resulting in the extension of piston  12 . 
     In operation, distribution block  7  will preferably be mounted on wrench assembly  1 . When wrench assembly  1  is used on an oil rig, the rig hydraulic lines will engage pressure line  18  and tank line  19 . The operator will engage threaded member  4  with socket  3  of drive head  2 . During make up, the operator will move operator control valve  15  from center position A to left position B. This will direct hydraulic fluid from pressure line  18  into motor branch  18 A and on into spin down motor  9 . When pressurized, spin down motor  9  will rotate, thereby turning socket  3  and threaded member  4  until spin down motor  9  torques out. When this happens, the operator will move operator control valve  15  into right position C. This will pressurize pilot valve line  22  and its extension and retraction branches  27  and  28 , if present. This will move pilot valve  23  from first position D to second position E or pilot valves  23 A and  23 B from first positions L and N to second positions M and O. When pilot valve  23  or pilot valves  23 A and  23 B are in second positions E or M and O, hydraulic fluid will be directed to extension side  16  of cylinder  6  and retraction side  17  will be connected to tank line  19 . Thus, when operator control valve  15  is in right position C, piston  12  and pawl  8  will extend and pawl  8  will engage ratchet teeth  5 , turning drive head  2 , socket  3 , and threaded member  4 . This will continue until piston  12  is fully extended. 
     When piston  12  is fully extended, the operator will return operator control valve  15  to center position A. This will connect pilot valve line  22  and its extension and retraction branches  27  and  28 , if present, to tank line  19 . In the absence of pressure in pilot valve line  22  or in extension or retraction branches  27  or  28 , pilot valve  23  or pilot valves  23 A and  23 B will return will direct hydraulic fluid to retraction side  17  of cylinder  6  while extension side will be connected to tank line  19 . Thus, when operator control valve  15  is in center position A, piston  12  and pawl  8  will retract out of engagement with ratchet teeth  5 . When pawl  8  has fully disengaged ratchet teeth  5 , the operator may return operator control valve  15  to right position C, and repeat the process until cylinder  6  torques out.