Abstract:
A pressurizing wedge assembly for a power transformer includes two mated wedges, each inscribed with locking transverse teeth and, in some embodiments, one of a pair of mating central alignment guides perpendicular to the teeth. The coil-side wedge has a cleat at the bottom to prevent it from slipping as the frame-side wedge is hammered into place. An alternative design uses three wedges, with two generally similar outer wedges and a center wedge with teeth and alignment guides on both sides. The wedges replace a system in which spreading pressure is applied alongside a gap into which a fixed block is inserted. The procedure of using hammers to drive the wedges can be replaced by a procedure in which power tools are employed.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates generally to power transformers. More particularly, the present invention relates to assembly of wiring structures within power transformers using nonconductive mechanical pressure fittings.  
       BACKGROUND OF THE INVENTION  
       [0002]     Very large electrical power distribution transformers, such as those used in facilities known as substations, use three-phase power at substantial voltages and currents, typically lowering the voltage drawn from long distance transmission lines and providing power to large customers—factories, apartment buildings, housing developments, and the like—which are in turn located in the vicinity of the substations. Comparable transformers are used at power plants and other facilities to step up voltage to levels suitable for application to long distance transmission lines. Once installed, if the load requirements of an installation remain largely unchanged, the transformers in a facility often can stand essentially untouched for decades, receiving little more attention than gas replenishment, visual and acoustical inspection, periodic functional testing, adjustments to the level and purity of the oil with which the transformers are filled, and cleaning of external surfaces to remove deposits that can promote arcing.  
         [0003]     Such transformers are subject to electrical stresses such as short circuit loads, phase imbalances, and the like, and can experience strong mechanical stresses generated by such electrical events. Demonstrations have shown that transformers with inadequate internal structure can flex sufficiently to rupture under conditions of high load, while properly structured transformers can withstand comparable load conditions.  
         [0004]     Establishing adequate internal structure in large transformers can require intensive labor and exacting craftsmanship. Methods and resources capable of simplifying and speeding the work of building—and of repairing—transformers with no sacrifice in reliability are potentially beneficial.  
         [0005]     Accordingly, it is desirable to provide a method and apparatus that make more consistent and more rapid the application of uniform vertical stack force at locations distributed around the perimeter of transformer windings prior to the enclosing and oil filling of the transformers.  
       SUMMARY OF THE INVENTION  
       [0006]     The foregoing needs are met, to a great extent, by the present invention, wherein in one aspect an apparatus is provided that in some embodiments provides a locking wedge apparatus that can be positioned largely permanently at any perimeter location where needed in a transformer, and that can be tightened, preferably using usual tools of the art, to exert a level of force recognized in the art as appropriate for stable transformer performance under load.  
         [0007]     In accordance with one embodiment of the present invention, a pressurizing wedge assembly for a transformer is presented. The pressurizing wedge assembly includes a coil-side wedge that bears against a transformer coil, and a frame-side wedge that bears against a transformer frame, wherein the frame-side wedge engages the coil-side wedge on respective engagement surfaces thereof, and wherein urging the coil-side and frame-side wedges with respect to one another in a direction to increase wedge assembly thickness applies pressure between the transformer frame and the transformer coil. In the wedge assembly, the engagement surface of the coil-side wedge and the engagement surface of the frame-side wedge interlock by respective pluralities of teeth, the respective teeth are configured to retain the wedges at a position with respect to one another absent application of sufficient urging force in the thickness increasing direction, and the respective teeth are configured to permit the wedges to slide with respect to one another in event of application of sufficient urging force in the thickness increasing direction.  
         [0008]     In accordance with another embodiment of the present invention, a pressurizing wedge assembly for a transformer is presented. The pressurizing wedge assembly includes a first interlocking wedge element that bears against a transformer coil surface, a second interlocking wedge element that bears against a transformer frame surface proximal to and oriented generally parallel to the transformer coil surface, and a third wedge element interposed between and interlocking with both the first wedge element and the second wedge element, wherein urging the third wedge element between the first and second wedge elements in a direction to increase wedge assembly thickness applies pressure between the transformer frame and the transformer coil.  
         [0009]     In accordance with yet another embodiment of the present invention, a pressurizing wedge assembly for a transformer is presented. The pressurizing wedge assembly includes means for applying normal force between an electrical winding and a frame surface proximal thereto along an axis generally perpendicular to the proximal frame surface within a transformer, means for measuring the normal force applied between the electrical winding and the proximal frame surface, means for incrementally altering a distance between the electrical winding and the proximal frame surface, and means for fixing the distance between the electrical winding and the proximal frame surface within a completed transformer, using the means for applying normal force, subsequent to altering the distance.  
         [0010]     In accordance with still another embodiment of the present invention, a method for applying pressure between a transformer coil and a transformer frame is presented. The method for applying pressure includes placing in contact with a transformer coil a coil-side pressurizing wedge having a generally planar coil-facing surface and a generally planar engagement surface that diverge, wherein the coil-facing surface of the coil-side wedge rests against a frame-facing surface of the transformer coil, inserting between the coil-side wedge and a transformer frame a frame-side pressurizing wedge having a generally planar frame-facing surface and a generally planar engagement surface that diverge at approximately the same angle as the coil-facing surface and the engagement surface of the coil-side wedge, wherein the engagement surface of the frame-side wedge contacts the engagement surface of the coil-side wedge and the frame-facing surface of the frame-side wedge contacts a coil-facing surface of the transformer frame, and wherein the coil-facing surface of the coil-side wedge is generally parallel to the frame-facing surface of the frame-side wedge, and applying force to the frame-side wedge with respect to the coil-side wedge in a direction to cause the respective engagement surfaces of the coil-side wedge and the frame-side wedge to traverse in a thickness increasing direction, thereby applying force to the transformer coil with respect to the transformer frame.  
         [0011]     In accordance with another embodiment of the present invention, a pressurizing wedge assembly for a transformer is presented. The pressurizing wedge assembly includes a first interlocking wedge element having a substantially planar first bearing surface, wherein the first bearing surface bears against a first surface of a first object external to the wedge assembly, wherein a second bearing surface of the first wedge element, distal to and oblique to the first bearing surface, has a plurality of locking ridges generally parallel to a line of intersection between a projection of a plane of the first bearing surface and a projection of a plane of the second bearing surface of the first wedge element, a second interlocking wedge element having a substantially planar first bearing surface, wherein the first bearing surface of the second interlocking wedge element bears against a first surface of a second object external to the wedge assembly, proximal to and oriented generally parallel to the first surface of the first object, wherein a second bearing surface of the second wedge element, distal to and oblique to the first bearing surface, has a plurality of locking ridges oriented generally parallel to a line of intersection between the projection of the plane of the first bearing surface and the projection of the plane of the second bearing surface of the second wedge element, wherein the second bearing surface of the first wedge element and the second bearing surface of the second wedge element lie in substantially parallel planes, wherein urging the first and second wedge elements with respect to one another in a direction to increase wedge assembly thickness applies pressure between the first object surface and the second object surface.  
         [0012]     There have thus been outlined, rather broadly, certain embodiments of the invention in order that the detailed description thereof herein may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional embodiments of the invention that will be described below and which will form the subject matter of the claims appended hereto.  
         [0013]     In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of embodiments in addition to those described and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting.  
         [0014]     As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods, and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]      FIG. 1  is a perspective view of a transformer assembly.  
         [0016]      FIG. 2  is a perspective view illustrating a pair of tightening wedges.  
         [0017]      FIG. 3  is an enlarged view of the groove structure according to  FIG. 2 .  
         [0018]      FIG. 4  is a perspective view of a three-part wedge system using separate alignment guide elements.  
         [0019]      FIG. 5  is a perspective view of a pair of wedges with an alternative tooth embodiment.  
         [0020]      FIG. 6  is a perspective view illustrating a pair of tightening wedges according to another embodiment of the invention.  
         [0021]      FIG. 7  is a perspective view illustrating a three-part wedge system according to another embodiment of the invention. 
     
    
     DETAILED DESCRIPTION  
       [0022]     The invention will now be described with reference to the drawing figures, in which like reference numerals refer to like parts throughout. An embodiment in accordance with the present invention provides interlocking and self-aligning wedges configured to fill at least in part and to apply pressure within a void provided for the wedges between the top of a winding in a transformer and an upper structural element of the transformer. In some two-wedge embodiments, the lower wedge has an outboard, downward projecting cleat that allows it to bear against the windings and other materials below, inhibiting motion by the lower wedge toward the center of the transformer winding core. The upper wedge, lacking an outboard cleat, is free to slide toward the center of the transformer winding. The interlocking characteristic of the wedges is realized with generally transverse grooves, the size and shape of which afford a range of wedge heights and provide suitable fineness of adjustment. The self-aligning characteristic of the wedges is realized with an alignment structure. The structure can be a longitudinal tongue and groove or similar discrete structure, or can be an underlying shape in the interlocking faces of the wedges, on which shape the grooves are superimposed. By means of such a structure, the wedges are constrained to maintain axial alignment. The wedges are made from a material that is largely non-flexible, non-frangible, non-conductive, and non-ferromagnetic, and is compatible with permanent immersion in a range of liquids including petroleum distillates. Adjustment of the wedges is preferably performed using a mallet, a sledgehammer, or a comparable mass impact tool, or using a C-clamp, hydraulic press, or comparable compression tool.  
         [0023]      FIG. 1  is a perspective view illustrating an embodiment of the present inventive apparatus and method. A transformer  10 , shown with a dashed element representing the approximate proportions of its outer housing  12 , has three coils  14 ,  16 , and  18  fitted over vertical core elements  20 ,  22 , and  24 , connected at bottom and top by core bridge assemblies  26  and  28 , respectively. A bottom frame assembly  30  holds the bottom core bridge  26  and stabilizes the bases of the core elements  20 ,  22 , and  24 , while a top frame assembly  32  performs a like function at the top of the core elements  20 ,  22 , and  24 . Between the two frame assemblies are lines of individual spacer ribs  34 , placed between each two turns of the coils  14 ,  16 , and  18 . Bottom spacer blocks  36  are fitted around the bottom between the coils  14 ,  16 , and  18  and the bottom frame assembly  30 ; these spacer blocks  36  bear much of the weight of the coils  14 ,  16 , and  18  plus any pressure applied to the coils  14 ,  16 , and  18  by top spacers  38 .  
         [0024]      FIG. 2  is a perspective view showing a pair of wedges  40  according to a two-wedge embodiment of the inventive apparatus. The lower wedge  42  has a locking surface  44  with a mean taper angle  46 , shown in more detail in  FIG. 3 , which taper is selected to provide a range of adjustment appropriate to the pressure range for a particular transformer configuration. The lower wedge  42  further has a cleat  48 , the inmost face  50  of which is configured to bear against the vertical outside surface of the coils  14 ,  16 , and  18  of  FIG. 1  when installed. The lower wedge  42  also has a bottom surface  52  which is configured to bear against the generally horizontal top surface of the coils  14 ,  16 , and  18  when installed. The lower wedge  42  has a central guide element  54  that can maintain alignment between the wedge pair  40  during installation and can maintain position stability over the life of the transformer  10 . Another characteristic of the wedge pair  40  is stepped locking surfaces  44  and  60 , respectively, likewise presented in greater detail in  FIG. 3 .  
         [0025]      FIG. 2  further shows an upper wedge  58 , oriented in the figure to show the upper wedge locking surface  60  that contacts the lower wedge locking surface  44 . A mating guide element  64  joins with the guide element  54  of the lower wedge  42  to maintain alignment. The top surface  66  of the upper wedge  58  in the embodiment shown is a generally smooth surface, allowing the upper wedge  58  to move with respect to the top frame assembly  32  shown in  FIG. 1 . The striking surface  68  of the upper wedge  58  accepts force by available means, such as blows from a hammer coupled through a block of a material similar to that of the wedges  40 , direct blows from a hammer or mallet, force applied using a compression band or a press, or other methods.  
         [0026]     Returning to  FIG. 1 , it is to be understood that ordinary construction of a transformer  10  calls for use of rectangular top spacers  38  of a thickness determined by design and workmanship for a model or sample of a transformer  10 , wherein the top spacers  38  are radially positioned substantially uniformly around the top of each coil  14 ,  16 , and  18  to establish a default distance from the top of the coil  14 ,  16 , and  18  to the surface of the top frame assembly  32 .  
         [0027]     As shown in  FIG. 1 , spacer ribs  34  are typically fitted between windings of the coils  14 ,  16 , and  18  at various locations around the perimeter of the respective coils  14 ,  16 , and  18 . When the top frame assembly  32  is assembled into place, testing establishes whether the top spacers  38  each provide sufficient force. A typical criterion for successful assembly of a top frame assembly  32  and associated top spacers  38  is determination whether at least one of the spacer ribs  34  can be caused to shift laterally by striking the spacer rib  34 . The striking test is typically performed, using a hammer of appropriate size, at an appropriate force level, with or without the use of a drift punch or like force transfer tool. Passing this test can be shown to correlate to the assembly procedure&#39;s having provided pressure in an acceptable range, so that final assembly will demonstrate that the transformer has been given correct internal structure.  
         [0028]     Continuing in  FIG. 1 , it is possible that the force at a location  72  is not sufficient—that is, a spacer rib  34  shifts when struck as described, or the equivalent. Lacking the inventive apparatus, the top spacer  38  vertically aligned with the failed location  72  is removed, which may require temporarily inserting combinations of setup spacers to either side of the location of the removed top spacer  38 , driving between the combinations of setup spacers one or more knifelike setup wedges to apply force to the affected coil  14  until the spacer  38  can be removed. Further pressure is then applied to the location  72 , until the affected coil  14  is pressed downward and away from the top frame assembly  32  at the location  72  sufficiently to enlarge a gap  74 . A replacement top spacer  38  somewhat thicker than the default top spacer  38 , or an assembly combining a spacer  38  and one or more added shims, is inserted in the gap  74 , after which the setup spacers and wedges are removed. This releases the setup pressure, and transfers the load to the oversized top spacer or assembly  38 . The work thus completed is thereupon evaluated as to the achieved pressure level.  
         [0029]     Should the test again fail, the sector is wedged open again, slightly wider than previously, and the top spacer  38  is replaced with a still thicker one, whereupon the setup wedge apparatus is removed and the test repeated for the failed spacer rib  34  and any others possibly affected by the adjustment.  
         [0030]     The inventive apparatus and method provide an alternative to the above tightening process. Once a location of insufficient tightness is identified, the standard top spacer  38  is removed, by the above method if required, and a lower wedge  42  and an upper wedge  58  as shown in  FIG. 2  are inserted. The wedges are fitted together at a convenient interlocking position, such as with the top face  66  of the upper wedge  58  roughly aligned with the upper extent of the lower wedge  42 , or with the height of the pair  40  slightly less than the unpressed height of the gap  74  in  FIG. 1 . The assembled wedge pair  40  is thereupon inserted into the gap  74  until the cleat  48  on the lower wedge  42  rests against the coil  14 , shown in  FIG. 1 . The upper wedge  58  is then urged inward toward the center of the coil  14 , using, for example, a sledgehammer, until the previously loose spacer rib  34  in the coil  14  is immobilized as in the prior method. Unlike the prior method, however, the operation is now complete, with the wedge pair  40  to be left in place. If, during a final checkout, some spacer ribs  34  pressed by wedge pairs  40  are found to be insufficiently tight, application of further tightening on the affected wedge pairs  40  can be performed with further hammer blows, rather than by repeated disassembly and reassembly using thicker and thicker top spacers  38 .  
         [0031]     The inventive apparatus and method may be applied equally in production and as a repair procedure for transformers in the field. Should testing indicate that a transformer of comparable construction and of any age has insufficiently tight construction, the transformer in  FIG. 1  can be drained of oil, at least in part, after which a manhole cover  76  can be removed, and a service person can enter the transformer housing  12  and perform the method at the location of the fault. Such a method may be significantly less onerous than the previous method, particularly since the iterative aspect of the previous method is significantly reduced. As noted above, a clamp device, such as a C-clamp having a screw thread, or a similarly-configured hydraulic ram, may be effective for reducing a mobility requirement inside the transformer housing  12 , compared to using a sledgehammer.  
         [0032]      FIG. 3  shows an auxiliary view of a portion of a stepped locking surface  80  of either of the wedges  40  as indicated in the callout in  FIG. 2 . The step size  82 , step surface angle  84 , and back slope angle  86 , like the mean wedge taper angle  88 , are determined by several criteria. The desired range of adjustment is a first such criterion, since a fully driven upper wedge  58 , as shown in  FIG. 2 , should preferably be inserted inward at least far enough not to protrude beyond the housing  12  limits as shown in  FIG. 1 , and not to cause interference with a wedge pair  40 , as shown in  FIG. 2 , on an adjacent coil surface if located near the proximal parts of two of the coils  14 ,  16 , or  18  in a transformer  10 , as shown in  FIG. 1 . The extent of compression is a related criterion. The total height and change in height of the coils  14 ,  16 , and  18  between fully relaxed and fully compressed determines the taper length and height change as the wedge pair  40  of  FIG. 2  are driven together. The step size  82  in  FIG. 3  determines the increment of change in pressure for each increment of advance. The step surface angle  84  defines in part the force required for each advance, while affecting position retention.  
         [0033]     Continuing in  FIG. 3 , the back slope angle  86  similarly affects position retention, along with ease of manufacturing and ruggedness of the wedges  40 , as shown in  FIG. 2 . That is, if the back slope angle  86  is, for example, perpendicular to the step surface angle  84 , manufacturing may be simplified, allowing the use of ordinary end mills in creating the wedges  40 , for example. A back slope angle  86  of less than ninety degrees with respect to the step surface angle  84  may provide stronger locking, but may make the tips of the steps less durable. An optimum combination of angles for a specific application may be determined in consideration of the processes to be employed in making the wedges  40 , such as milling versus molding, as well as properties such as toughness and injection molding flow properties of the materials used.  
         [0034]      FIG. 4  shows a three-part wedge assembly  90  in which both the bottom wedge  92  and the top wedge  94  are substantially similar to the lower wedge  42  in  FIG. 2 , except omitting the cleat  48  in the embodiment shown, while the middle wedge  96  has steps  98  and guide provisions  100  on two opposed surfaces  102  and  104 . Where the configuration of the top frame assembly  32  of  FIG. 1  is compatible with using a cleat, adding cleats to the bottom and top wedges  92  and  94 , respectively, as in the bottom wedge  42  in  FIG. 2 , may show advantage in some embodiments. Since, if equipped with cleats, neither of the wedge assembly surfaces  106  and  108  that contact other transformer components can move appreciably with respect to other transformer components during installation, all motion then takes place between elements of the three-part wedge assembly  90 . All angles and other dimensions are likely to require analysis and validation, as determined by the required adjustment range, the materials used, and other criteria. Since individual step advances between both the bottom  92  and middle  96  and the top  94  and middle  96  wedges can occur largely simultaneously with a three-part wedge assembly  90 , the rate of advance per step, and thus the required force, can roughly double. In some embodiments, a shallower slope may be preferred in order to permit lower applied force levels in proportion to the final pressure achieved.  
         [0035]     The guides  110  in  FIG. 4  are shown as separate components, so that the guide provision  100  resembles a keyway-and-key arrangement, with equivalent recesses in all three wedges  92 ,  94 , and  96 . This configuration may be advantageous in some embodiments.  
         [0036]     Construction of wedges according to  FIGS. 2 and 4  preferably includes a sufficient thickness of material to withstand the applied forces, such as to prevent overstress of the region of transition from wedge to cleat during installation. Maximum material thickness may be a function of cost and fabrication limitations for materials, such as available thickness limits for transformer-compatible materials to be machined, or limitations on molding thickness for materials to be injection molded. In some embodiments, wedges may be co-positioned with parallel-faced spacers to increase overall thickness.  
         [0037]      FIG. 5  is a perspective view of a pair of wedges  120  with an alternative tooth embodiment. It is to be understood that references to transverse teeth herein include configurations in which the tooth profile does not necessarily follow a straight line. In  FIG. 5 , for example, the lower and upper wedges  122  and  124 , respectively, are shown to have teeth  126  formed in vees or chevron shapes of greater or lesser steepness; such teeth can be cut along an arcuate or other nonlinear path, rather than having two linear sections  128 , if preferred. In the configuration shown, the wedges  122  and  124  are to at least some extent self-aligning without need for a separate alignment guide feature. The edges of the tooth sections  128  in the wedge pair  120  shown in  FIG. 5  lie in a plane as indicated by the dashed surface  130 .  
         [0038]      FIG. 6  is a perspective view of another pair of wedges  132  wherein the corresponding tooth sections  134  lie in two intersecting planes, also shown in  FIG. 7 .  
         [0039]      FIG. 7  is a perspective view of a three-wedge system  136  wherein tooth sections  138  and  140  lie in intersecting planes  142  and  144 , respectively. Intersecting planes  142  and  144  meet at a reference plane  146  through the midline of the assembled wedges  136 . The effect of this arrangement is to provide self-centering without a separate guide feature, as in the embodiments of  FIGS. 5 and 6 .  
         [0040]     Selection of materials for wedges according to the inventive apparatus includes several considerations. Temperature range for a transformer during manufacture may exceed 150 degrees Celsius, while operating temperatures may be higher still, so a selected material should preferably withstand such temperatures with known and acceptable changes in its physical properties. Additionally, within a transformer, physical dimensions of steel and copper components, as well as fill fluids, change with temperature, so applied stress can vary with temperature. Thus, the selected material should have a thermal coefficient of expansion that is compatible with those of other materials in the transformer.  
         [0041]     Removal of moisture and other fluid contaminants from a transformer during construction or overhaul can include prolonged application of relatively hard vacuum at elevated temperature, so outgassing properties of a candidate wedge material should be known and should be compatible with the materials of the transformer. A typical transformer is filled, during sequential manufacturing and overhaul steps, with a succession and a variety of petroleum distillates. These distillates can leave residues and can be subjected to breakdown during transformer operation, so the wedge material should also be chosen for compatibility with all of the manufacturing, operational, and breakdown products to be found in the transformer.  
         [0042]     Mechanical forces during assembly include final loads in some embodiments that can be on the order of 50 Kg/cm 2 . The wedge material thus requires sufficient hardness to withstand this considerable static loading, with a multiplier for impacts applied during assembly, for loads due to thermal changes, and for structural safety margins. In addition, the environment within a transformer includes strong electromagnetic forces, with varying magnetic fields as well as electrical currents present. Thus, the wedge material should preferably have low conductivity and satisfactory dielectric and dissipation constants, as well as being substantially free of ferromagnetic properties, including contaminants and effects of aging in the environment described.  
         [0043]     Although an example of the wedge is shown in which a first wedge element has a cleat that bears against coil windings, and a second wedge element is driven radially inward using a hammer or similar tool, it will be appreciated that numerous cleatless configurations can be used, and that in any configuration, force can be applied using a hand or power operated tool such as a screw clamp or a hydraulic press with opposing jaws to draw the wedges together without bearing on the coils. Further, while the tightening motion described is radial and directed inward within each coil in a transformer, circumferential tightening motion is possible with both the two-part and three-part wedge embodiments, where the wedges are oriented circumferentially rather than radially.  
         [0044]     While evaluation of force levels is described using a hammer to attempt to cause a shift in the position of a spacer, an embedded strain gauge within a suitably designed spacer, or another comparable measuring device, can be provided, to directly or indirectly detect the force applied by the wedges. Also, although the wedges are useful to assemble power transformers for the electrical power distribution industry, they can also be used for a variety of other controlled pressure applications in which it is preferable to include an adjustable element that is sufficiently stable mechanically, thermally, electromagnetically, and chemically, as well as sufficiently low in cost, to permit the element to be left in place.  
         [0045]     The many features and advantages of the invention are apparent from the detailed specification, and, thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to that fall within the scope of the invention.