Cylinder synchronizer for drilling equipment
United States Patent 1191 Childs et a1.  
 [ CYLINDER SYNCHRONIZER FOR DRILLING EQUIPMENT [76] Inventors: Willard D. Childs, PO. Box 582,  
 Olivenhain, Calif. 92024; A. Bruce Duncan, 540 Boulevard, Piedmont, Calif. 94610 [22] Filed: Oct. 1, 1973 [21] Appl. No.: 402,145  
 [52] US. Cl 254/189 R; 254/139; 92/137; 92/61 [51] Int. Cl. F01b 1/00 [58] Field of Search 92/137, 61, 76; 91/186; 173/147; 254/139 R, 188, 189 R [56] References Cited UNITED STATES PATENTS 464,786 12/1891 Jastrow 254/188 1,379,378 5/1921 Lastrow 92/137 2,240,794 5/1941 Mason 92/137 2,786,361 3/1957 Russell 92/137 3,355,993 12/1967 Williamson 92/137 FOREIGN PATENTS OR APPLICATIONS 1,115,033 11/1954 France 92/137 [451 Apr. 15, 1975 Primary ExaminerPaul E. Maslousky Attorney, Agent, or Firm-Lothrop &amp; West [57] ABSTRACT A cylinder synchronizer is especially useful in drilling equipment having a main frame. A hook frame is mounted to rise and fall along a vertical center line relative to the main frame under the influence of a pair of vertically disposed, hydraulically interconnected cylinders. The plungers of the cylinders are each provided with one of a pair of pulleys over which flexible straps extend. One end of each strap is connected to the main frame while the other end of each strap passes over a respective one of the pulleys and at its other end is connected by connecting pins to one of a pair of spaced, selected points on the hook frame. The selected points are on opposite sides of the center of the hook frame and are at about the same elevation. On the hook frame is a hook support connected at a point substantially midway between the selected points and disposed at an elevation lower than that of the selected points.  
 2 Claims, 2 Drawing Figures PATENTEDAPR 1 sums FIG 1 PATENTEDAFR 1 wins FlG 2 CYLINDER SYNCI-IRONIZER FOR DRILLING EQUIPMENT In the operation of various kinds of hoisting equipment, particularly drilling equipment, it is desired to utilize a plurality of hydraulically interconnecting cylinder mechanisms incorporating plungers, but a problem arises in that the plungers can get out of synchronization or space relationship due to slight differences in the areas of the cylinders, due to momentary differences in hydraulic pressure therein and possibly due to other causes. Lack of synchronization leads to chattering of the parts, instability of the operation of the structure and accelerated failure of the cylinder packings and bearings. Sometimes unsynchronized plungers bind in the cylinders, thus introducing problems due to high friction and lateral loads of an excessive nature.  
  It is therefore an object of our invention to provide a cylinder synchronizer useful in connection particularly with hoisting or drilling equipment in which the two cylinders are utilized without any substantial difficulty due to the above-noted problems.  
  A further object of the invention is to provide a cylinder synchronizer that utilizes a pair of cylinders each exerting substantially the same lifting load on the material being handled and occupying the same travel positions despite free hydraulic interconnection between the cylinders.  
  A further object of the invention is to provide a cylinder synchronizer that will maintain cylinder plungers approximately in the same horizontal point in the vertical path location when subjected to a joint vertical load, despite hydraulic interconnection of the cylinders.  
  Another object of the invention is in general to provide an improved cylinder synchronizer.  
  A still further object of the invention is in general to provide an improved arrangement of hydraulic mechanism in drilling or other hoisting equipment.  
  Other objects, together with the foregoing, are attained in the embodiment of the invention described in the accompanying description and illustrated in the accompanying drawings, in which:  
  FIG. 1 is in part a diagram showing important portions of a cylinder synchronizer constructed in accordance with the invention and incorporated in a drilling device; and  
  FIG. 2 is a diagram illustrating terms, forces, moments and positions involved in the mechanism of FIG. 1 and its explanation.  
  In a typical installation, the cylinder synchronizer pursuant to the invention is incorporated in hoisting or drilling equipment. This includes a supporting structure 6 carried by any suitable arrangement at an appropriate elevation from the ground or from the water. Connected to the holding mechanism 6 is a main frame 7 symmetrical about a vertical center line 8. The main frame 7 includes on one side a first hydraulic cylinder 9 and on the other side, about equally spaced from the center line, includes a comparable, second hydraulic cylinder 11. The cylinders are appropriately connected to the usual hydraulic mechanism so that the cylinders can be filled and emptied under control and the cylinders are hydraulically interconnected through a cross duct 12 so that there is relatively free hydraulic interflow therebetween. In one type of installation each of the cylinders is also provided with a pneumatic chamber 13 interconnected therewith. Such chamber is shown only on the left cylinder 9 in FIG. 1 in order to improve the clarity of the showing, although a comparable chamber is usually afforded for the cylinder 11.  
  Adapted to reciprocate vertically in the cylinder 9 is a first plunger 14 and arranged similarly to reciprocate vertically within the second cylinder 11 is a second plunger 16. The plungers are preferably about the same bore as the cylinders and project from the upper end therefrom. It is equally feasible to provide pistons in each of the cylinders connected by relatively smaller piston rods to the outside. In any event, the vertically movable members extend upwardly from the cylinders 9 and 11.  
  The plunger 14 at its upper end carries a pulley 17 rotatable about a journal pin 18 on the plunger center line, while similarly the plunger 16 carries a pulley l9 connected&#39;thereto by a journal pin 21 disposed on the center line.  
  Fastened to the main frame 7 at one end by a securing device 22, preferably adjustable, is a flexible strap 23 conveniently a length of multiple chain having considerable flexibility with respect to the curvature of the pulley 17 and effective to act as a multiplier for the motion of the plunger 14. In a similar fashion there is a second, flexible strap 24 at one end connected to the main frame by an adjustable connector 26 and running over the pulley 19. The strap 23 has a relatively long, vertically extending flexible portion 27, whereas the strap 24 has a relatively long, vertically extending portion 28.  
  At their other ends, both of the straps are secured to a hook frame 31. This is a body disposed generally symmetrically with respect to the center line 8 and provided with a connector 32 for receiving a hook 33 or equivalent hoisting device. The lower end of the strap 23 is secured to the hook frame 31 at one side of the center line 8 by means of a pivot pin 34 so that there may be relative rotary motion between the lower end of the flexible strap and one side of the hook frame. Comparably, the other strap 24 adjacent its lower end is connected by a pivot pin 36 to the hook frame 31. The pins 34 and 36 are preferably disposed about equidistantly from the center line 8 on opposite sides thereof and are located at about the same elevation or in the same horizontal plane. The connector 32 is preferably located about on the center line 8 midway between the pins 34 and 36 but at an elevation substantially lower than that of the pins 34 and 36.  
  As particularly shown in FIG. 2, the center line 8 is represented by a solid line L while the connecting points of the hook frame 31 are generally represented by an isosceles triangle defined by three apices, the upper lefthand one of which is designated point 1 and corresponds with the axis of the first pin 34. The triangle has a second apex at point 2 corresponding to the center line of the second pin 36. The third apex, point 3, is representative of the hook connector 32 and is generally on the center line at a substantially lower elevation than the common horizontal elevation points 1 and 2 occupy. The hook frame 31 is a relatively heavy, symmetrical body, the center of gravity of which is disposed at point 4 on the center line L (or 8) at an elevation between that of the points 1 and 2 and that of the point 4.  
  The effect of the arrangement, as shown in FIG. 1, is that if one of the plungers moves higher, for example,  
 than the other, the hook frame 31 twists slightly changing the moments in a direction to restore the synchronization. This operation can be analyzed pursuant to the foregoing values in accordance with the following analysis.  
  The various relationships as shown especially in FIG. 2 are set forth in the table below:  
 R The angle of hook frame rotation due to unbalanced forces F, The force exerted by the first plunger (at point F The force exerted by the second plunger (at point 2) DP The force difference between F, and F W, The reaction load due to F, and F B The horizontal distance between points 1 and 2 A The horizontal distance from point 2 (force F to the vertical center line L (8) H The height of the triangle W,- The force exerted by the weight of the hook frame C The vertical distance from the base line (plane of point 2) to the center of gravity of the hook frame (point 4) X, The horizontal distance from point 2 to point 1 due to rotation of frame B cos R X, The horizontal distance from point 2 to point 3 due to rotation of frame A cos R H sin R X, The horizontal distance from point 2 to point 4 due to rotation of frame A cos R C sin R Y, The vertical displacement of point 1 with respect to point 2 B sin R DX, The horizontal displacement of point 1 due to rotation of the frame X, A DX,, The horizontal displacement of point 3 due to rotation of the frame F Vertical forces M Moments (about point 2).  
 The analysis is based on taking moments about point 2, as shown in FIG. 2. The relationship of the parts is as set forth above, and as follows for equilibrium:  
  For quite small angles; for example, with R something less than 10 and for H of a comparable value to or greater than A, then It is thus apparent that with the physical arrangement set out in FIG. 1 and diagrammatically shown in FIG. 2, the load is normally on the hook 33 and is equally suspended from and supported by the two hydraulic cylinders 9 and 11 which normally move in synchronism. If that is true, then the forces are represented by the solid line showings in FIG. 2. If, however, for some reason one of the plungers, such as 14, moves slightly higher in the cylinder 9 than does the corresponding interconnected plunger 16 in the cylinder 11, then the force diagram is illustrated by the broken line showing in FIG. 2. This indicates that the plunger which gets ahead or too far upwardly concurrently reduces its moment arm and operates thereafter against the reduced moment arm. The moment and corresponding displacement are reduced until such time as the plunger for the other or opposite interconnected cylinder is able to catch up. At this time the triangular hook frame 31 is again rotated back to its intermediate position with the point 3 coinciding with the center line. A num&#39; ber of minor excursions and corrections of this sort can occur in both directions or rotation; that is, either about point 2, as explained, or in exactly the same manner but in the reverse sense about point 1. In this fash ion the two plungers are maintained in close synchronism at all times. Any lateral forces that tend to arise are immediately compensated for. There is no sticking of the plungers in the cylinders, there is no binding nor excessive friction and the mechanism is completely synchronized under all operating conditions.  
 What is claimed is:  
  l. A cylinder synchronizer for drilling equipment comprising a main frame, means for pendulously suspending said mainframe, a hook frame, a pair of fluid motor cylinders mounted on said main frame with means for equalizing fluid pressures therein, a pair of plungers each reciprocably mounted in a respective one of said cylinders and extending upwardly there from, a pair of pulleys each rotatably mounted at the upper end of a respective one of said plungers, a pair of flexible straps each secured at one end to said main frame then passing over a respective one of said pulleys and at the other end disposed adjacent said hook frame, a pair of pivot pins each connecting said other ends of said straps to said hook frame at selected laterally spaced points on opposite sides of said hook frame for supporting a hook at a support point substantially midway between said selected points and at an elevation lower than that of said selected points.  
  2. A cylinder synchronizer for drilling equipment comprising a main frame, means for pendulously suspending said main frame, a hook frame having a vertical center line, a pair of interconnected hydraulic motor cylinders mounted on said main frame, a pair of plungers each reciprocably mounted in a respective one of said cylinders, a pair of flexible straps each having a portion extending substantially vertically from said main frame, means for moving each of said portions relative to said main frame in accordance with reciprocation of a respective one of said plungers, means for articulating each of said straps to a respective one of two selected points on said hook frame disposed on opposite sides of said center line at approximately the same elevation, and means on said hook frame for supporting a hook at a support point on said center line and at an elevation lower than that of said selected points.  
  UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3:877 68Q Dated April 15, 1975 Willard D. Childs et a1.  
 Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:  
 On the cover sheet insert I 6? 1731 Assignee: The Rucker C mpany 1-.  
 Signed and sealed this 24th day of June 1275.  
  BEA- Attest- C 1 2 223131? I. I UTE 3. IEASOI&#39;? Commissioner of Patents stinrr Officer and Trademarks CC USCOMM&#39;DC 60376-P69 U.5. GOVERNMENT PRINT NG OFFICE: e 9 93 FORM PO-105O (IO-69)