Patent Number: 063209233
Section: description

DESCRIPTION OF THE PREFERRED EMBODIMENT A locking device 10 according to the present invention is shown in FIG. 1. In one embodiment, the locking device 10 assists a restraining ring 34 and a wedge 18 in supporting a jet pump downcomer 11 in a desired position. Typically, the restraining ring 34 supports the downcomer 11. In the embodiment shown, the downcomer 11 is located inside the restraining ring 34 at the ring's inner peripheral surface 33, FIG. 1. Two adjustable screws 36 and the wedge 18 position the downcomer 11 within the restraining ring 34. The adjustable screws 36 extend through the restraining ring 34, and each screw is located on an opposing side of the restraining ring 34. The wedge 18 is located between the restraining ring 34 and the downcomer 11, and is largely held in place by gravity. The wedge 18 includes a vertically extending surface 32 that contacts the downcomer 11. The wedge 18 is carried by a guide bolt 20. Two guide blocks 22, 24 carried by the exterior surface of the downcomer 11 support the guide bolt 20 in an axial direction relative to the downcomer 11. In the preferred embodiment, each guide block 22, 24 is welded to the downcomer 11. The locking device 10 is fabricated of stainless steel, and includes an upper jaw 12, a lower jaw 14, and a tightening screw 16. The locking device 10 is lightweight, and may be easily installed and maintained by those of ordinary skill in the art. When installed on the downcomer 11, the upper jaw 12 and the lower jaw 14 are vertically disposed such that the upper jaw 12 rests against the top surface 31 of the wedge 18 and the lower jaw 14 is located below the wedge 18. The upper jaw 12 and the lower jaw 14 are rectangularly-shaped members. Both the upper jaw 12 and the lower jaw 14 include a distal end 28, 30, respectively, and a proximate end 25, 15, respectively. The distal ends 28, 30 are each moveably supported by the guide bolt 20. In one embodiment, the distal ends 28, 30, respectively, define a hook 26(a), 26(b). Each hook 26(a), 26(b) is movably positioned around the guide bolt 20. As shown in FIGS. 1, 2 and 3, the tightening screw 16 extends between the upper jaw 12 and the lower jaw 14. Specifically, the tightening screw 16 supports the proximate ends 15 and 25, respectively, of the upper jaw 12 and the lower jaw 14. As illustrated in FIGS. 1 and 2, a housing 38 retains the tightening screw 16. The housing 38 defines a recess 40 that receives the restraining ring 34. As the tightening screw 16 is tightened, the upper jaw 12 and the lower jaw 14 move toward one another. When the tightening screw 16, is turned in the opposite direction, the upper jaw 12 moves away from the lower jaw 14. The tightening screw 16 is actuated remotely using techniques known in the field, as the locking device is located inside a nuclear reactor. The tightening screw 16, once the desired torque has been applied, is prevented from turning by a reusable locking crimp (not shown) carried by the tightening screw 16. The locking crimp is of the type commonly known and used by those of ordinary skill in the art. The locking action of the crimp may be easily overcome if readjustment is required at a later time in the field. It will be appreciated that a force inducing member such as a spring loaded member may replace the tightening screw 16. One spring loaded member may be placed on both the upper jaw 12 and another on the lower jaw 14 such that compressive forces are generated at each of the upper jaw 12 and the lower jaw 14. As discussed below, the squeezing action of the compressive forces firmly holds the restraining ring 34 against the wedge 18, thus retaining the downcomer 11 in the desired position. OPERATION In order to secure the downcomer in position, the wedge 18 and restraining ring 34 are subjected to compressive forces induced on the upper jaw 12 and the lower jaw 14 by tightening the tightening screw 16. As the tightening screw 16 is turned to move the upper jaw 12 and the lower jaw 14 toward one another, the upper jaw 12 induces a downward force on the top surface 31 of the wedge 18. In turn, the compressive force on the lower jaw 14 induces an upward force on the bottom surface of the restraining ring 34. The compressive forces generated against the top of the wedge 18 and the bottom of the restraining ring 34 firmly hold the wedge 18 and restraining ring 34 in contact, forcing the wedge 18 against the downcomer 11 so as to lock the downcomer 11 in a desired position. In the embodiment shown, the compressive force on the lower jaw 14 creates an upward force on the bottom surface of the wedge 18, causing the wedge to move slightly upward. As the wedge 18 moves upward, the bottom surface 42 of the recess 40 contacts the restraining ring 34, forcing the restraining ring 34 against the wedge 18. Simultaneously, the tightening screw 16 causes a downward force on the upper jaw 12 that is transferred to the surface 31 of the wedge 18. Consequently, the wedge 18 moves slightly downward against the restraining ring 34. As a result, the upward motion of the restraining ring 34 is impeded by the downward motion of the wedge 18, resulting in the wedge 18 being pressed tight against the restraining ring 34. This arrangement creates a clamping action that frictionally engages the restraining ring 34, the wedge 18 and the downcomer 11, resulting in the downcomer 11 being secured in the desired position. There are a variety of configurations that may be employed to fabricate apparatus 10. Thus, the disclosed embodiment is given to illustrate the invention. However, it is not intended to limit the scope and spirit of the invention. Therefore, the invention should be limited only by the appended claims.