Patent Publication Number: US-6713681-B2

Title: Insulating insert for magnetic valves

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a division of U.S. patent application Ser. No. 09/798,532 filed on Mar. 2, 2001, now U.S. Pat. 6,536,741, which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to magnetic valves. More particularly the invention relates to an insulating insert for magnetic air valves. Such find use in control systems of railroad locomotives. 
     2. Description of the Related Art 
     Magnetic air valves, also known as magnet valves, solenoid valves, and electric air valves, are generally well known in the art. Typically such valves and valve assemblies comprise a magnetically energizable core encased in a metal housing having an open front end and a closed rear end. The metal housing usually has an upper front hole having a removable strain relief wire connector or hollow bolt attached therethrough. The such wire connectors typically house wires for actuating the magnetic core inside the housing. 
     With such magnetic valves, air flow typically occurs only when certain spool valves are open. A plunger, actuated by the magnetic core, is supported in a bore through both the rear of the metal housing and through the magnetic core. The plunger cooperates with a spool valve member to shift the spool valve member upon energizing of the magnetic core from an open to a closed position, or vice versa, as desired. Such valves are commonly used in locomotive control systems. 
     The problem to be solved is that during actuation of the valve, there are rapidly succeeding shock movements that may vibrate the magnetic valves and the wires therein. With vibration over time, the wires may fray and/or come into contact with the metal walls of the magnetic valve housing, thus shorting out the valve, tripping a control breaker, and shutting down the locomotive. It would therefore be desirable to provide a device for minimizing electrical contact between the wires and the metal housing of the magnetic valve. The present invention provides a solution to this problem. 
     The invention comprises an insulating insert for separating wires from an inside metal wall of the magnetic valve housing. The insert comprises an electrically insulating sleeve having side walls, top and bottom opposite open ends, and a threaded bushing attached around a hole through one side wall of the sleeve. The bushing engages a removable, hollow, strain relief wire connector or hollow bolt of the magnetic valve, which wire connector contains wires running into the housing to form the requisite electrical connections with the magnetic core of the valve. The insert also preferably includes an insulating flange around the perimeter of the top open end of the sleeve to thereby further insulate the housing, and to provide a seal between the housing and an optional covering. 
     SUMMARY OF THE INVENTION 
     The invention provides an insulating insert for a magnetic valve which comprises: 
     a) a hollow, electrically insulating sleeve having sidewalls defining a top open end and a bottom open end opposite to the top open end; one of the side walls having a circular hole therethrough; and 
     b) a threaded bushing fixedly attached to the sidewall around the circular hole. 
     The invention further provides an insulating insert for a magnetic valve which comprises: 
     a) a hollow, electrically insulating sleeve having sidewalls defining a top open end and a bottom open end opposite to the top open end; one of the side walls having a circular hole therethrough; 
     b) a threaded bushing fixedly attached to the sidewall around the circular hole; 
     c) an electrically insulating flange around a perimeter of the top open end, which flange projects substantially perpendicularly to said sidewalls, and which flange comprises a pair of opposing fastening holes therethrough; and 
     d) an electrically insulating covering in contact with the flange around the perimeter of the top open end of the sleeve. 
     The invention still further provides a magnetic valve assembly which comprises: 
     a) a magnetic valve comprising: 
     i) a metal housing having a top open end and a bottom closed end, an upper front hole through a front side of the metal housing near the top open end, and two opposing lower holes through opposite front and back sides of the metal housing near the bottom closed end; 
     ii) a magnetic core having conductive connectors, and a central bore therethrough, which magnetic core is positioned within the bottom closed end of the metal housing such that the conductive connectors face in a direction towards the top open end of the metal housing, and that the central bore of the magnetic core is concentrically aligned with the two opposing lower holes through the opposite front and back sides of the metal housing; 
     iii) a removable strain relief wire connector positioned through the upper front hole in the metal housing; and 
     iv) conductive wires electrically attached to the conductive connectors of the magnetic core within the metal housing of the valve, which wires run through the wire connector and out of the magnetic valve; and 
     b) an insulating insert comprising: 
     i) a hollow, electrically insulating sleeve having sidewalls defining a top open end and a bottom open end opposite to the top open end; one of the side walls having a circular hole therethrough; and 
     ii) a threaded bushing fixedly attached to the sidewall around the circular hole; 
     which insert is positioned within the top open end of the magnetic valve such that the sidewalls of the electrically insulating sleeve are in contact with an inside surface of the metal housing, the strain relief wire connector engages the threaded bushing of the insulating insert within the magnetic valve such that a first end of the wire connector extends into the metal housing while a second end of the wire connector remains outside of the housing, and the conductive wires of the magnetic valve run from the conductive contacts, into the bottom open end of the insulating insert, through the wire connector, and out of the magnetic valve. 
     The invention still further provides a process for electrically insulating a magnetic valve which comprises: 
     a) providing a magnetic valve comprising: 
     i) a metal housing having a top open end and a bottom closed end, an upper front hole through a front side of the metal housing near the top open end, and two opposing lower holes through opposite front and back sides of the metal housing near the bottom closed end; 
     ii) a magnetic core having conductive connectors, and a central bore therethrough, which magnetic core is positioned within the bottom closed end of the metal housing such that the conductive connectors face in a direction towards the top open end of the metal housing, and that the central bore of the magnetic core is concentrically aligned with the two opposing lower holes through the opposite front and back sides of the metal housing; 
     iii) a removable strain relief wire connector positioned through the upper front hole in the metal housing; and 
     iv) conductive wires electrically attached to the conductive connectors of the magnetic core within the metal housing of the valve, which wires run through the wire connector and out of the magnetic valve; and 
     b) providing an insulating insert which comprises: 
     i) a hollow, electrically insulating sleeve having sidewalls defining a top open end and a bottom open end opposite to the top open end; one of the side walls having a circular hole therethrough; and 
     ii) a threaded bushing fixedly attached to the sidewall around the circular hole; and 
     c) positioning the insulating insert within the top open end of the magnetic valve such that the sidewalls of the electrically insulating sleeve are in contact with an inside surface of the metal housing, the strain relief wire connector engages the threaded bushing of the insulating insert within the magnetic valve such that a first end of the wire connector extends into the metal housing while a second end of the wire connector remains outside of the housing, and the conductive wires of the magnetic valve run from the conductive contacts, into the bottom open end of the insulating insert, through the wire connector, and out of the magnetic valve. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a front view of an insulating insert according to the invention. 
     FIG. 2 shows a top view of an insulating insert according to the invention. 
     FIG. 3 shows a perspective view of an insulating insert according to the invention. 
     FIG. 4 shows a perspective view of a box shaped electrically insulating covering according to the invention. 
     FIG. 5 shows a perspective view of a plate shaped electrically insulating covering according to the invention. 
     FIG. 6 shows a top view of a magnetic valve housing. 
     FIG. 7 shows a side cross sectional view of a magnetic valve assembly without an insert according to the invention. 
     FIG. 8 shows a side cross sectional view of a magnetic valve assembly including an insert according to the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The invention provides an insulating insert for a magnetic air valve. Such insulating inserts serve to electrically insulate a magnetic valve and thereby prevent shorting and/or other electrical problems which may result from contact between the magnetic valve and any wires or other electrically conductive objects within the valve. 
     FIGS. 1-3 show an insulating insert  10  according to the invention. As shown in these Figures, the insert  10  preferably comprises a hollow, electrically insulating sleeve  5  having sidewalls  6  defining a top open end  11  and a bottom open end  13  opposite to the top open end  11 . The sleeve  5  is preferably shaped to fit inside a magnetic valve such that the sidewalls  6  of the sleeve  5  are in contact with inner walls of the magnetic valve which typically comprise metal. The sleeve  5  preferably serves to electrically insulate the magnetic valve by preventing contact between inner walls of the magnetic valve with wires or other electrically conductive objects within the valve. The sleeve  5  preferably comprises an electrically insulating material. Suitable electrically insulating materials nonexclusively include homopolymers and copolymers of polyesters, polyolefins, polyurethanes, nylons, polycarbonates, acrylonitriles, dienes, styrene, acrylics, rubbers and combinations thereof. 
     Preferably, one of the sidewalls  6  has a circular hole  4  therethrough. The insert  10  preferably comprises a threaded bushing  3  fixedly attached to the sidewall  6  around the circular hole  4 . The bushing  3  preferably has inner threads, and is capable of engaging threaded objects such as strain relief wire connectors, bolts, and the like. In a preferred embodiment, the bushing  3  is capable of engaging a removable strain relief wire connector of a magnetic valve, as described below, to secure the insert  10  to the magnetic valve. Typical magnet valves often include a nut or lock ring (not shown) to secure such wire connectors or bolts to the valve. Vibrations often cause such nuts or lock rings to become loose, falling into the valve and resulting in shorting. The bushing  3  is preferably fixedly attached to the sleeve  5  to prevent such shorting. Suitable materials for the threaded bushing  3  nonexclusively include electrically insulating materials such as those described above for the electrically insulating sleeve  5 . Materials for the threaded bushing are preferably selected independently from those materials used for the electrically insulating sleeve  5  or any other electrically insulating component of the invention. 
     In a preferred embodiment, the insert  10  further comprises an electrically insulating flange  7  attached around a perimeter of the top open end  11  of the sleeve  5 , which flange  7  projects substantially perpendicularly to said sidewalls  6  as shown in FIG.  3 . The electrically insulating flange  7  preferably serves to further insulate and protect a magnetic valve from contact with wires and/or other electrically conductive objects, and to provide a seal between the magnetic valve and an optional electrically insulating covering (not shown). The flange  7  preferably comprises an electrically insulating material. Suitable electrically insulating materials nonexclusively include those materials described above for the electrically insulating sleeve  5 . Materials for the flange are preferably selected independently from those materials used for the electrically insulating sleeve  5  or any other electrically insulating component of the invention. The flange  7  preferably further comprises a pair of opposing fastening holes  9  therethrough which serves to fasten the insulating insert  10  to a magnetic valve, an electrically insulating covering (not shown) or other object by means of screws. 
     The insert  10  may optionally further comprise an electrically insulating covering. Such electrically insulating coverings  30  may be of any suitable shape such as an open box, shown in FIG. 4, or a plate, shown in FIG.  5 . The optional electrically insulating covering  30  serves to further insulate a magnetic valve and its contents from contact with wires and/or other electrically conductive objects, and provides protection against water penetration and the like. This may be done by providing an electrically insulated covering  30  which comprises an electrically insulating material, and which engages the perimeter of the top open end  11  of sleeve  5 , or a flange  7  around the perimeter of the top open end  11  of sleeve  5  to thereby cover the top open end  11  of sleeve  5  of the insulating insert  10 . FIG. 4 shows one embodiment of a covering  30 , wherein the covering is box shaped and comprises sidewalls  36  having an outer surface and an inner insulating surface, a bottom closed end  38  having an outer surface and an inner insulating surface, a top open end  34  opposite the bottom closed end  38 , which top open end  34  is surrounded by an insulating perimeter  35 . FIG. 5 shows another embodiment of a covering  30 , wherein the electrically insulating covering is plate shaped and comprises a flat insulating surface  32 . The electrically insulating coverings  30  of FIGS. 4 and 5 preferably comprises a pair of opposing fastening holes  39  therethrough which serve to fasten the covering  30  to a magnetic valve, or to the insulating insert  10  according to the invention. Suitable electrically insulating materials for the optional electrically insulating covering nonexclusively include those materials described above for the electrically insulating sleeve  5 . Materials for the electrically insulating covering are preferably selected independently from those materials used for the electrically insulating sleeve  5  or any other electrically insulating component of the invention. 
     FIGS. 6-7 show a known magnetic valve  20  for use with the present invention. Magnetic valves for use with the present invention may also be referred to as solenoid valves, magnetic air valves, or electric air valves, and are generally well known in the art. Suitable magnetic valves are available commercially from Graham-White of Salem, Va. FIG. 6 shows a top view of a magnetic valve  20  comprising a metal housing  19  having an top open end  12  and a bottom closed end  14 . FIG. 6 shows an upper front hole  18  through a front side of the metal housing  19  near the top open end  12 . As shown in FIG. 7, the magnetic valve comprises two opposing lower holes  17  through opposite front and back sides of the metal housing  19  near the bottom closed end  14 . The magnetic valve  20  further comprises a magnetic core  26  having conductive connectors  24  and a central bore  16  therethrough, which core  26  is positioned within the bottom closed end  14  of the metal housing  19  of valve  20  such that the conductive connectors  24  face in a direction towards the top open end  12  of the metal housing  19 , and that the central bore  16  of the magnetic core  26  is concentrically aligned with the two opposing lower holes  17  through opposite front and back sides of the metal housing  19 . FIGS. 6 and 7 also show a removable strain relief wire connector  28  which is capable of being inserted through the front hole  18  of the metal housing  19 . According to the invention, other threaded objects such as threaded tubes, pipes, hollow bolts, and the like may be used in place of the strain relief wire connector. In a preferred embodiment, the wire connector  28  comprises an electrically insulating material on an inside surface of the wire connector. Suitable electrically insulating materials nonexclusively include those described above for the electrically insulating sleeve  5 . As shown in FIG. 7, conductive wires  22  are preferably electrically attached to the conductive connectors  24  of the magnetic core  26  within the metal housing  19  of the valve  20 . These wires  22  are preferably capable of running through the strain relief wire connector  28  and out of the valve  20 . 
     FIG. 8 shows an insulating insert  10  of the invention, in use with a magnetic valve  20 . As shown in FIG. 8, an insert  10  according to the invention is positioned within the top open end  12  of the valve  20 . The insert  10  is preferably positioned such that the sidewalls  6  of the electrically insulating sleeve  5  are in contact with an inside surface of the metal housing  19  of the valve  20 . Preferably, the strain relief wire connector  28  of the magnetic valve  20  engages the threaded bushing  3  of the insulating insert  10  within the magnetic valve  20  such that a first end of the wire connector  28  extends into the metal housing  19  while a second end of the wire connector  28  remains outside of the housing  19 . It is also preferred that the conductive wires  22  of the valve  20  run from the conductive contacts  24 , into the bottom open end  13  of the insert  10 , through the strain relief wire connector  28 , and out of the magnetic valve. In a most preferred embodiment, the insert  10  further comprises an electrically insulating flange  7 , which flange  7  engages an outer perimeter of the open front end  12  of the metal housing  19  when the insert  10  is positioned within the open front end  12  of the magnetic valve  20 . The insulating insert  10  of the present invention preferably prevents contact between the wires  22  and an inner surface of the metal housing  19  which may cause shorting or other electrical problems of the valve  20 . 
     While the present invention has been particularly shown and described with reference to preferred embodiments, it will be readily appreciated by those of ordinary skill in the art that various changes and modifications may be made without departing from the spirit and scope of the invention. It is intended that the claims be interpreted to cover the disclosed embodiment, those alternatives which have been discussed above and all equivalents thereto.