The present invention relates to methods to repair used electrode assemblies in acoustic shock wave generating devices such as lithotripters.
Acoustic shock waves are created when a high voltage discharge spark passes between two coaxially aligned opposing electrode tips. In the presence of a fluid the energy is released by the spark which flashes the water to steam creating an acoustic wave wherein a series of such waves can pass through tissue to break up concrements within the body.
Preferably, the fluid around the electrode tips is a saline solution to enhance electro conductivity. In some electrode assemblies the fluid surrounding the tips is also charged with carbide particles to further increase conductivity. Such a device is described in U.S. Pat. No. 6,113,560 entitled “Method and Device For Generating Shock Waves For Medical Therapy, Particularly For Electro-Hydraulic Lithotripsy” issued Sep. 5, 2000.
As can easily be appreciated the spark generated by the voltage discharge can create a large amount of heat which tends to burn the tips of the opposing electrode conductors. As the tips burn, the spark gap distance increases resulting in even higher voltages to create a discharge. At some point this dramatically degrades the shock wave pulses generated rendering the electrode assembly non effective. This situation can occur in a very quick time meaning the replacement of the electrode assemblies is done after every second, third or fourth patient procedure. While these devices are adapted for rapid change over or replacement it is also noted that each assembly can cost as much as several hundred dollars.
Accordingly, the device described in U.S. Pat. No. 6,113,560 has been touted as having a longer time of useful capacity and better gap distance maintenance than other similar devices. While this is true, the replacement cost is offset by the high end price demanded for the product.
In U.S. Pat. No. 6,849,994 granted Feb. 1, 2005 in a patent entitled “Electrode Assembly for Lithotripters” the same owner of the U.S. Pat. No. 6,113,560 describes the need for refurbishing electrode assemblies used in lithotripters by providing easily replaceable tips. In that patent the inventors noted that a prior art electrode with an insulating layer required the insulating layer to be machined off the inner conductor prior to replacement of the discharge tip and then reapplication of the insulating layer, presumably by remolding the plastic insulating layer over the inner conductor. Naturally this was a labor intensive practice that was cost prohibitive. It was their idea to provide threaded replacement tips that could easily been replaced when burnt to refurbish a used electrode assembly. This, they argued, could greatly reduce replacement cost.
The present inventive method has found a simple quick and very precise method to repair those electrode assemblies without removable tips that were believed to be too costly to repair. No grinding or machining of the insulator layer was required.
The number of such used devices is extremely large and therefore an efficient repair process would be invaluable to the physicians using such a lithotripter having those types of electrode assemblies.
The following description and drawings provide a novel way in which repair of such devices is not only feasible but highly efficient.
A method of repairing a used electrode device is disclosed wherein the method has the steps of providing a used electrode assembly having an inner conductor with an integral electrode tip encapsulated in an insulator body having an outer conductor and an outer electrode tip; and pressing the inner conductor with integral electrode tip while holding or restraining the insulator body to apply an force sufficient to overcome at least partially the adhesion forces at the mating surfaces of the inner conductor and the insulator body. Thereafter by grasping an end of the inner conductor opposite the tip while holding the insulator body and withdrawing the inner conductor from the insulator body the parts can be separated. Then by measuring the amount the inner electrode tip has been burnt as compared to a new tapered tip to establish a cut distance ΔX; and recutting the tip by machining the burnt portion along the tip taper surface toward and into a shoulder of the inner conductor by a distance equal to the cut distance ΔX the electrode tip can be reshaped.
The inner conductor further has a shoulder taper surface extending from an end adjacent a base of the integral electrode tip; and the method further includes the step of recutting the shoulder taper shoulder by machining the outside diameter of the inner conductor at a distance ΔX beyond the intersection of the shoulder taper surface and the diameter of the conductor along the same angle to form a conical surface of the same diametrical dimensions as the original shoulder surface.
In one embodiment the method further includes cutting a pair of legs of the burnt outer electrode at a distance D extending outwardly from the insulator housing to leave two protruding leg portions; placing the insulator body with two protruding leg portions in a half of a split fixture, wherein the slip fixture has two halves each with an interior surface molded or otherwise shaped to replicate the exterior surface of the insulator body; placing an outer electrode with two legs into the fixture wherein the two legs overlap the pair of cut leg portions embedded in the insulator body; setting the distance of the overlap to replicate the proper gap distance; closing the fixture securing the outer electrode against the projecting legs; introducing a pair of welding tips through holes in the fixture exposing the overlapping leg portions; and pressing the welding tip against the legs and welding a leg of the outer tip to the projecting leg portion. This method may also include slipping a pair of insulator tubes over the legs and moving the insulators to a central portion of the electrode prior to placing in the fixture and welding the legs; and moving an insulator over each welded leg portion after welding. Thereafter by re-inserting a recut of an inner conductor into an insulator body and pressing the conductor until fully seated in the insulator body to form an assembly.
This repaired used electrode assembly prior to repairing has an outer sleeve attached to the insulator body, the sleeve being filled with a particle suspended fluid and the sleeve being retained by a metal ring at the location of attachment to the insulator body and prior to the step of removing the inner conductor from the insulator body the method further may require placing the electrode assembly in a fixture with a collet holding the metal ring tin place; pushing on the sleeve to release the ring; and removing the assembly from the fixture and separating the sleeve from the insulator body. Thereafter the step of emptying the fluid into a container while filtering the suspended particles may be used along with the steps of removing a particle holding container from the sleeve; opening the container; recharging the container with particles; and closing the refilled container and reinserting into the sleeve, the sleeve has two vent holes that can be sealed by sealing the vent holes with a tape labeled “remove prior to use”; filling the sleeve with saline solution; placing the metal ring around the sleeve; placing the repaired electrode assembly into the filled sleeve and pressing the metal ring over the sleeve and insulator body joint to tightly seal the assembly.
The invention will be described by way of example and with reference to the accompanying drawings in which:
With reference to
The first step in disassembling the electrode assembly 1 is to place the sleeve 11 in a fixture 30 with a collet collar 32 that grasps the ring 20 holding it in place and thereafter a rod 31 pushes the plastic sleeve 11 free of the ring 20 as shown in
As shown in
With reference to
With reference to
At the other side of the electrode assembly device 1, the electrode tip 4 must be inspected. If the outer electrode tip 4 is sufficiently burnt at the transverse tip portion 4C, then it needs to be repaired in such a fashion that the original gap setting S can be established. In order to accomplish this task the unique method of repairing this electrode device 1 is accomplished by taking two electrode devices 1, where one device has a sufficiently undamaged electrode tip 4 that can be polished and cleaned. On each leg 4A and 4B, of that electrode 4 the legs are cut from the insulator housing body 8 and cleaned as indicated, as shown in
As shown in
At this point the electrical inner conductor 9 with a recut electrode tip 3 is placed back into the end of the main insulator body 8 and is pressed fit back into position by placing the electrode 4 in an arbor and having the plastic body 8 in a fixture is possible to smoothly press the conductor 9 back into position as shown in
Contrary to what was previously reported by the manufacturer it is not required that the insulator material body 8 be cut or ground from the inner conductor 9, but it can simply be pressed off the inner conductor 9 such that all the components can be repaired, cleaned and reused once the electrode tips 3 and 4 are repaired. These repairs enable the entire device 1 to be repaired in such a fashion that is available for use and the performance characteristics are identical to that of the new electrode. This ability to repair these types of assemblies provides a significant cost savings to the end user. This repaired device provides good spark gap control over a decent amount of use making it desirable that such a device be reusable without requiring an entire new electrode assembly to be purchased, simply because the tips have burnt down slightly and need to be redressed as shown above.
This repair method while requiring several steps to accomplish is fairly simple in its process as described above and as can be seen accomplishes a repair that meets all of the criteria that the original device had maintained when originally sold. Secondly, the method as described above teaches that the outer electrode 4 could be cut from another electrode assembly and reinstalled on a second electrode assembly as described above. However, it is also possible that one does not need to cut the outer electrode 4 along the two legs, but rather can simply clean those electrodes while also removing the inner conductor and recutting the electrode 3 integral thereto as described above as an alternative method of repair. However, it is also possible that one does not need to cut the outer electrode 4 along the two legs, but rather can simply clean those electrodes while also removing the inner conductor and recutting the electrode 3 integral thereto as described as an alternative method of repair.
As an additional alternative repair, it is possible the method described above can provide a new outer electrode 4 of similar shape and construction. The new electrode 4 can be welded onto place as described above to achieve the desired result. In this fashion the cannibalization of two electrode devices 1 to build one electrode device 1 would not be required and the repair process would simply replace the outer electrode such that the assembly can be repaired in that fashion prior to being repackaged and reused. These and other alternative constructions are possible when using the method as described above which unexpectedly and very simply is capable of disassembly and reassembly in such a fashion that these electrode assemblies 1 can be easily repaired and put back into service.
Variations in the present invention are possible in light of the description of it provided herein. While certain representative embodiments and details have been shown for the purpose of illustrating the subject invention, it will be apparent to those skilled in this art that various changes and modifications can be made therein without departing from the scope of the subject invention. It is, therefore, to be understood that changes can be made in the particular embodiments described which will be within the full intended scope of the invention as defined by the following appended claims.
The present application is a divisional patent application, and incorporates by reference, U.S. patent application Ser. No. 11/609,972 filed on Dec. 13, 2006 entitled “Method for Repairing an Electrode Assembly”.
Number | Name | Date | Kind |
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3110093 | Johnson | Nov 1963 | A |
3781986 | Joslyn et al. | Jan 1974 | A |
6113560 | Simnacher | Sep 2000 | A |
6849994 | White et al. | Feb 2005 | B1 |
Number | Date | Country |
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4013509 | Oct 1991 | DE |
Entry |
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Office Action dated Apr. 22, 2009 in U.S. Appl. No. 11/609,972, filed Dec. 13, 2006 for “Method for Repairing an Electrode Assembly”. |
Office Action dated Sep. 17, 2009 in U.S. Appl. No. 11/609,972, filed Dec. 13, 2006 for “Method for Repairing an Electrode Assembly”. |
Number | Date | Country | |
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20100101067 A1 | Apr 2010 | US |
Number | Date | Country | |
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Parent | 11609972 | Dec 2006 | US |
Child | 12652162 | US |