Patent Publication Number: US-6220200-B1

Title: Line marker with locking mechanism

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to line markers for marking the location of utility lines and the like. More particularly, the present invention relates to a line marker having a locking mechanism for removably securing a line marker to a post or tube. 
     2. Prior Art 
     Thousands of miles of buried utility lines form part of the infrastructure connecting communities and utility services around the world. Such utility lines include gas and oil lines, power lines, electrical and/or fiber optic telecommunication and/or cable television lines, water lines, sewer lines, and the like. In is often desirable and necessary to mark the location of these lines to assist utility workers in maintaining the lines and prevent inadvertent disturbance of the lines. Line markers are often used to identify the location of the buried lines and are located above or near ground level. The markers usually have indicia, such as writing, to indicate the type of line being marked. The markers may also contain some type of warning concerning the buried line. 
     In addition, some markers may double as cathodic protection test stations. Thus, the marker, or similar structure, may contain electrical wires that extend between the utility line and the marker, where they may be accessed by utility workers. The wires may be used to monitor the utility line, such as with cathodic protection 
     It is desirable that the markers be highly visible so that they may be readily located by utility workers and immediately observably by others. It is also desirable that the markers be durable to resist environmental conditions. Because of the number of markers required to mark long lengths of utility lines, it is desirable that the markers be inexpensive and readily available. 
     One disadvantage with some markers is their use of custom shaped markers which require specially shaped posts and marker members. For example, some markers employ markers with square cross sections requiring posts with square cross sections. Because many of the markers are located in remote areas, it is desirable that they be resistant to vandalism and abuse, such as theft or gun shots. Another disadvantage with some markers is their succeptability to molestation. For example, some markers are easily destroyed by bullets or are easily removed. Therefore, it would be advantageous to develop a line marker which is highly visible and meets the many diverse requirements for identifying, protecting, and monitoring underground utility lines. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a line marker which is highly visible. 
     It is another object of the present invention to provide a line marker which is resistant to adverse whether conditions. 
     It is a further object of the present invention to provide a line marker which is resistant to vandalism and other abuse. 
     It is a further object of the present invention to provide a line marker which discourages unauthorized removal. 
     It is a further object of the present invention to provide a line marker which may contain a cathodic protection circuit. 
     These and other objects and advantages of the present invention are realized in a line marker apparatus having a locking ring and cap marker disposed on a support tube. The tube is an elongated tubular member having a first end configured for insertion into the ground, a second end configured for extending upwardly, and a tube wall having an outer or exterior surface and an annular cross-section. The locking ring is disposed on the exterior surface of the second end of the tube and includes at least one locking finger extending from the ring. The locking finger is preferably bendable inwardly from the ring and towards a longitudinal axis of the tube. 
     The cap is removably coupled to the locking ring and has a cap wall defining a contained hollow volume and an open end for receiving the locking ring. The cap advantageously has a protrusion extending into the hollow of the cap for contacting the locking finger and forcing the locking finger towards the longitudinal axis, and thus the tube. The locking ring advantageously is completely received within the cap, thus concealing how the cap is attached and discouraging tampering or unauthorized removal by vandals. The cap wall also has an outer surface and may have an indentation formed in the outer surface of the wall for receiving indicia. This indicia may include safety warnings or processing information. A transparent window also may be disposed in the indentation for protecting the indicia. 
     The locking ring also has a top edge and a bottom edge. The wall of the locking ring may have a slot formed therein extending between the top edge and the bottom edge to vent the hollow of the cap. Alternatively, the cap wall may have a slot formed therein extending as a vent to the hollow 
     The at least one finger has an upper end opposite the ring with an edge for digging into a surface, such as an outer surface of the tube. The at least one finger also has an inner surface and at least one rib advantageously is formed on the inner surface of the finger to prevent the ring from rotating on the tube. 
     The locking ring has an outer surface and may have threads formed thereon. The cap also has an inner surface and may have threads formed thereon which engage the threads of the locking ring. The cap is rotatable about the longitudinal axis with respect to the locking ring. As the cap rotates on the locking ring the cap advances and retracts on the locking ring along the threads 
     Preferably, a plurality of resilient locking fingers are provided and extend from the ring wall generally parallel to the longitudinal axis. Each locking finger has an outer surface. The cap is preferably elongated and also has an inner surface defining a hollow therein. The annular protrusion extends into the hollow of the cap member and contacts the outer surface of the locking fingers for forcing the locking fingers in towards the longitudinal axis As the cap rotates on the locking ring and advances and retracts, the annular protrusion advances and retracts along the length of the fingers to bend the fingers in towards the longitudinal axis, and into binding contact with the outer surface of the tubular member 
     These and other objects, features, advantages and alternative aspects of the present invention will become apparent to those skilled in the art from a consideration of the following detailed description taken in combination with the accompanying drawings. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded view of a preferred embodiment of a line marker apparatus of the present invention with a tube. 
     FIG. 2 is a perspective view of the preferred embodiment of the line marker apparatus of the present invention disposed on the tube. 
     FIG. 3 is a partial cross sectional view of the preferred embodiment of the line marker apparatus of the present invention taken along line  4 — 4  of FIG. 5, with the tube removed. 
     FIG. 4 is a partial cross sectional view of the preferred embodiment of the line marker apparatus of the present invention disposed on the tube, taken along line  4 — 4  of FIG.  5 . 
     FIG. 5 is a cross sectional view of the preferred embodiment of the line marker apparatus of the present invention disposed on the tube, taken along line  5 — 5  of FIG.  2 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made to the drawings in which the various elements of the present invention will be given numerical designations and in which the invention will be discussed so as to enable one skilled in the art to make and use the invention. 
     As illustrated in FIGS. 1 and 2, a line marker apparatus, indicated generally at  10 , is shown in combination with a support tube or post  14  The line marker apparatus  10  of the present invention will be described with particular reference for use in marking utility lines, although it is to be understood that the apparatus may be used in marking any desired object, and also may be suited for additional uses, such as cathodic protection test stations. Such utility lines include, for example, gas and oil lines, power lines, electrical and/or fiber optic communication and/or cable television lines, water lines, fewer lines , and the like. 
     The tube or post  14  is an elongated tubular member with a tube wall  20  The tube wall preferably has an annular cross-section and an outer or exterior surface  22  defining a hollow passage  24  extending through the tube  14 . A first end  16  of the tube  14  is configured for insertion into the ground while a second end  18 , or upper end, of the tube  14  is configured for extending upwardly A longitudinal axis  26  extends through a center of the tube or post  14  which is oriented generally vertical. 
     The tube  14  is preferably a standard size tube which is readily available. For example, the outer diameter of the tube  14  may be 3.5 inches, or standard 3½ inch tubing. The length of the tube  14  may be any desired length, but is generally 4 to 6 feet long. In additions the tube  14  is buried in the ground at a desired depth so that the upper end  18  of the tube  14  protrudes vertically from the ground to a desired height. Furthermore, the tube  14  may be made of any desired material, such as plastic or metal, and thus may be plastic tubing or metal pipe. The standard size of the tube  14  insures that there will be adequate supplies of posts for use in marking long lengths of utility line and that the tubes will be easy to obtain for repair or replacement. 
     Referring to FIG. 1, the line marker apparatus  10  of the present invention includes a locking ring  30 , or annular member, and a cap  34 , cap marker, or marker member. The locking ring  30  advantageously locks or maintains the locking ring  30  and cap  34  on the tube  14 . 
     The locking ring  30  may be removably disposed on the exterior surface of the second or upper end  18  of the tube  14 , as shown in FIG.  4 . The locking ring  30  is a cylindrical or annular member with a ring wall  38 . The ring wall has an annular cross-section, as shown in FIG. 5. A longitudinal axis  42  extends through a center of the locking ring  30 ; and may be coaxial with the longitudinal axis  26  of the tube  14  when the locking ring  30  is disposed on the tube  14 . Screw threads  50  are formed on an outer surface  46  of the ring  30 . An inner surface  54  of the ring  30  contacts the outer surface  22  of the tube  14  when the locking ring  30  is disposed on the tube  14 , as shown in FIG.  4 . The locking ring  30  also has a top edge  58 , or second end; and a bottom edge  60 , or first end. 
     The inner diameter of the locking ring  30  or ring wall  38  is sized to receive the tube  14 . Preferably the inner diameter is sized to snugly fit over the tube  14 . Thus, the inner diameter of the locking ring  30  may be substantially the same as an outer diameter of the tube  14 , or 3.5 inches or greater. The inner diameter, however, may be sized to slide more freely over the tube  14 . Thus, the inner diameter of the ring  30  may be sized slightly larger than the outer diameter of the tube  14 . A slightly larger inner diameter allows for dimensional tolerances in the outer diameter of the tube  14  and the inner diameter of the ring  30 , and for dimensional variations due to temperature. 
     A plurality of locking fingers  62  advantageously are formed on the locking ring  30  for locking or maintaining the locking ring  30  on the tube  14 . The locking fingers  62  extend from the top edge  58  of the ring wall  38  generally within the cylindrical profile of the ring wall  38 , and toward the second end  18  of the tube  14  when the locking ring is disposed on the tube, as shown in FIG.  4 . In addition, the fingers  62  extend vertically, and generally parallel to the longitudinal axis  42 . The fingers  62  may be extensions of the ring wall  38 , or formed by a plurality of gaps or spaces  66  in the ring wall  38  between each finger  62 . 
     Each locking finger  62  has an outer surface  70 , as shown in FIGS. 3, and an inner surface  74 . The inner surface  74  of the fingers  62  contacts the outer surface  22  of the tube  14  when the locking ring  30  is disposed on the tube  14 , as shown in FIG.  4 . The fingers  62  are preferably somewhat flexible and resilient. In addition, the fingers  62  are preferably bendable into binding contact with the tube  14 , or outer surface  22  of the tube  14 , to hold the locking ring  30  on the tube  14 . 
     In addition, one or more ribs  78  advantageously are formed on each locking finger  62 , as shown in FIGS. 1 and 3, for preventing rotation of the ring  30  with respect to the tube  14  when the ring  30  is disposed on the tube  14 , as shown in FIG.  4 . The ribs  78  are formed on the inner surface  74  of the fingers  62  and are generally parallel with the longitudinal axis  42 . The ribs  78  engage the outer surface  22  of the tube  14  and prevent or hinder the ring  30  from rotating on the tube  14 . Preferably, at least one locking finger  62  has at least one rib  78 . Most preferably, each locking finger  62  has one or more ribs  78 . 
     Referring to FIG. 4, each locking finger  62  has an upper end  82 , or second end, opposite the ring wall  38 . An interior edge  86  advantageously is formed on each locking finger  62  for digging into the outer surface  22  of the tube  14  to prevent removal of the ring  30 . The edge  86  preferably forms a sharp angle, or is a sharp edge. Preferably, at least one locking finger  62  has a sharp edge  86 . More preferably, each locking finger  62  has a sharp edge  86 . 
     The locking ring  30  may be a unitary member formed from a single piece of material, such as plastic. For example, the locking ring  30  may be formed of plastic by injection molding. 
     Referring again to FIG. 1, the cap or cap member  34  provides the line marker function for drawing attention to the location of the buried utility line and indicating the type of line. Thus, the size and color of the cap  34  are designed to draw attention to the cap and convey appropriate information. Preferably the cap  34  is elongated to provide a sufficiently visible surface. For example, the length of the cap  34  may be approximately 18 inches. In addition, the shape of the cap  34  is configured to be visible for many or all directions. Preferably the shape of the cap  34  is substantially circular or cylindrical to present a visible and/or reflective surface from all directions. 
     The cap  34  has a tubular cap wall  90  with a generally annular cross section or that is generally cylindrical, as shown in FIG.  5 . The cap wall  90  has an inner surface  94  and defines a hollow  98  therethrough. A first end  102 , or lower end, of the cap  34  is open while a second end  106 , or upper end, of the cap  34  is preferably enclosed. The open first end  102  receives the tube  14  and locking ring  30 , as discussed below. The enclosed second end  106  protects the locking ring  30  and hollow  98  from adverse elements, such as rain. The cap  34  may by partially conical and tapper slightly from the first end  102  to the second end  106 . A longitudinal axis  108  extends through a center of the cap  34 . 
     Screw threads  110  are formed on the inner surface  94  of the cap wall  90  at the first end  102  and threadedly engage the threads  50  of the locking ring  30 . Thus, the cap  34  may be removably coupled to the locking ring  30  by rotating the cap  34  with respect to the locking ring  30 , or rotating the locking ring  30  with respect to the cap  34 . In addition, the cap  34  may be removably disposed on the second end  18  of the tube  14  when the locking ring  30  is disposed on the tube  14 , as shown in FIG.  4 . Thus, the cap  34  and ring  30  rotate with respect to one another and rotate about the longitudinal axis  42  and/or  108 . 
     Referring to FIGS. 3 and 4, the cap  34  advantageously has an annular protrusion  120  formed on the inner surface  94  of the cap wall  90 . The annular protrusion  120  extends into the hollow  98  of the cap  34  towards the locking ring  30  or locking fingers  62  when the cap  34  threadedly engages the locking ring  30 , or when the locking ring  30  is disposed in the cap  34 . The annular protrusion  120  advantageously contacts the outer surface  70  of the locking fingers  62  for forcing the locking fingers  62  into contact with the outer surface  22  of the tube  14 , as shown in FIG.  4 . 
     The annular protrusion  120  is formed in the cap wall  38  and has an angled or tapered surface  122  which is angled with respect to the longitudinal axis  108 . The protrusion  120  or angled surface  122  is formed by the inner surface  94  of the cap wall  38  tapering inwardly from the first end  102  to the second end  106 . The protrusion  120  may be formed by a change in diameter of the cap wall  38 . The protrusion  120  reduces the inner diameter of the cap  34  or cap wall  38 . The inner diameter of the protrusion  120  nearer the first end  102 , or the beginning of the angled surface  122 , is preferably larger than the outer diameter of the locking ring  30  or ring wall  38 , or the outer diameter at the upper end  82  of the fingers  62 . The inner diameter of the protrusion  120  nearer the second end  106 , or at an end of the angled surface  122 , is preferably less than the outer diameter of the locking ring, or the outer diameter at the upper end  82  of the fingers  62 . Thus, the upper end  82  of the fingers  62  contacts the angled surface  122  of the protrusion  120  and the angled surface  122  tends to bend the fingers  62  inwardly or towards the longitudinal axis  108  and/or  42  and the tube  14 . 
     As indicated above, the cap  34  is rotatable about the longitudinal axis  108  and/or  42  with respect to the locking ring  34  and tubular member  14  As the cap  34  is rotated with respect to the locking ring  30 , the threads  50  and  110  advance or retract the cap  34  on the locking ring  30 . As the cap  34  advances or retracts, the annular protrusion  120  also advances and retracts along the length of the fingers  62 . As indicated above, the upper end  82  of the fingers  62  encounters the angled or tapered surface  122  of the protrusion  120  Thus, as the cap  34  is advanced on the locking ring  30 , or the locking ring is received into the cap  34 , the angled surface  122  tends to force or bend the fingers  62  into binding contact with the outer surface  22  of the tube  14 . 
     The cap  34  also may be a unitary member formed from a single piece of material, such as plastic. For example, the cap  34  may be formed of plastic, such as Lexan, by injection molding. 
     The method of using the line marker apparatus  10  of the present invention includes mounting the tube or post  14  in the ground such that the second or upper end  18  of the tube  14 , and thus the cap  34 , is located at a desired height, usually with the cap  34  at eye level. The tube  14  may be inserted into a hole dug to the desired level or may be driven into the ground to the desired level. 
     The locking ring  30  is disposed on the upper end  18  of the tube  14  with the upper end  18  inserted into or received within the ring  30  As discussed above, the inner diameter of the ring  30  and/or the ribs  78  preferably is sized to snugly fit the outer diameter of the tube  14 . The ribs  78  preferably engage the outer surface  22  of the tube  14  to hold the ring  30  vertically on the tube  14 . As discussed above, the fingers  62  are resilient and flexible. Thus, the inner diameter of the ribs  78  may be slightly less than the outer diameter of the tube  14  so that the fingers  62  must bend slightly outwardly away from the tube  14  as the ring  30  is inserted over the tube  14  The resilient or spring-like nature of the fingers  62  advantageously biases the ribs  78  or inner surface  74  of the fingers  62  against the outer surface  22  of the tube  14 , thus maintaining the ring  30  vertically on the tube  14 . The ribs  78  also advantageously prevent the ring  30  from rotating on the tube  14 . 
     The cap  34  is disposed over the locking ring  30  and the second end  18  of the tube  14  with the locking ring  30  and the second end  18  of the tube  14  inserted into or received within the open first end  102  of the cap  34 . The cap  34  is rotated about the longitudinal axis with respect to the locking ring  30  and tube  14  such that the threads  110  of the cap  34  engage the threads  50  of the locking ring  30  and advance the ring  30  into the cap  34 . The ribs  78  engaging the tube  14  prevent the cap  34  from rotating the ring  30 . As the cap  34  advances with respect to the ring  30 , the fingers  62  advance with respect to the protrusion  120  and abut the protrusion  120 . The protrusion  120  or angled surface  122  advantageously forces or compresses the inner surface  74  of the fingers  62  against the outer surface  22  of the tube  14 . In addition, the protrusion  120  advantageously may force the edge  86  of the upper end  82  of the fingers  62  into the outer surface  22  or tube wall  20 . Thus, the fingers  62  bear against the tube  14 . 
     Therefore, the fingers  62  bearing against the outer surface  22  of the tube under the force of the protrusion  120  advantageously prevent the line marker apparatus  10 , or the cap  34  and ring  30 , from being vertically displaced or pulled vertically from the tube or post  14 . The fingers  62  compressed against the tube  14  lock the ring  30  and cap  34  to the tube  14 . 
     As shown in FIGS. 3 and 4, with the cap  34  coupled to the locking ring  30 , the ring  30  preferably is completely received within the cap  34 , or the open first end  102  of the cap  34 . Thus, the locking ring  30  is concealed by the cap  34  from casual observance; as shown in FIG.  2 . To the casual observer, the cap  34  will appear coupled to the tube  14  permanently, as there is no visible means of attachment. Any pull on the cap  34  will confirm that the cap  34  is indeed secured to the tube  14 , thus discouraging any further tampering. Therefore, the line marker apparatus  10  of the present invention advantageously prevents unauthorized removal by potential vandals because the locking ring  30  is concealed by the cap  34  and secures the cap  34  to the tube  14 . In addition, with the edge  86  of the fingers  62  digging into the tube  14 , any vertical pulling force on the cap  34  tends to cause the fingers  62  to further dig into the tube  14  and further secure the cap  34  to the tube  14 . 
     In addition, the line marker apparatus  10  of the present invention advantageously is easily removable from the tube  14 . Thus, the tube  14  and/or marker  10  may be serviced or replaced. After many years of service it may be necessary to replace the marker or cap  34 . In addition, any components located in the tube, or accessed through the tube, may also be serviced or replaced. For example, a valve may be located at the base of the tube  14  and accessed by an elongated wrench after removing the cap. Furthermore, any components located on the tube or under the cap (in the hollow of the cap) may also be serviced or repaired. For example, the tube may convey wires from an underground line to a cathodic protection test station disposed on the tube under the cap. 
     To remove the line marker apparatus  10  of the present invention from the tube  14 , the cap  34  may be rotated in the opposite direction. As the cap  34  rotates with respect to the ring  30 , the cap  34  and ring  30  are retracted from one another. In addition, the protrusion  120  is withdrawn from the fingers  62 , thus removing the force compressing the fingers  62  against the tube  14 . The cap  34  may be completely withdrawn from the ring  30 , or may be retracted sufficiently that the protrusion  120  releases the fingers  62  from the tube  14 . After the cap  34  is unthreaded and removed from the ring  30 , or sufficiently retracted from the ring  30  such that the fingers  62  no longer hold the ring  30  to the tube  14 , the ring  30  may be removed from the tube  14 . Therefore, the cap  34  may be easily removed, but the method of removal is not readily apparent. 
     Referring to FIGS. 1,  2  and  5 , the cap  34  also has an outer surface  130  As indicated above, the outer surface  130  or cap wall  94  is preferably generally circular or cylindrical to provide a 360 degree view of the marker  10 . Indicia  134  may be disposed on the outer surface  130  of the cap  34 . The indicia  134  may be warning symbols or words, and/or may be informative symbols or words, and/or may be a highly visible indicator to draw attention to the marker. For example, the indicia may be in bright and contrasting colors to draw attention to the marker, include symbols or words of warning, and/or information about the buried line. The indicia  134  may be directly formed in the material, such as during the injection molding process, printed directly on the outer surface  130 , or attached to the outer surface, such as a sticker. 
     The cap  34  advantageously may have one or more indentations  138  formed in the cap wall  38  or outer surface  130  of the cap  34  for receiving the indicia  134 . For example, the indentation  138  may receive a sticker-type indicia  134 . The indentation  138  helps prevent the edges of the sticker from peeling off the outer surface  134 . The indentations  138  are preferably arc-shaped, like the surface  130 , to provide  360  degree visibility. A transparent window  142  may also be disposed in the indentation  138  to further protect the indicia  134 . The window  142  may be removably disposed in the indentation  138 . The window  142  is preferably arc-shaped to fit in the arc-shaped indentation. 
     Referring to FIG. 5, the locking ring  30  advantageously may have a slot  140  formed in the outer surface  46  of the ring wall  38  to vent the hollow  98  of the cap  34 . The slot extends from the top edge  58  of the wall  38  to the bottom edge  60 , as shown in FIG.  1 . Alternatively, the locking ring  30  may have a slot  144  formed in the inner surface  54  of the ring wall  38 . Alternatively, the cap  34  may have a slot  148  formed in the inner surface  94  of the cap wall  90  and extending into the hollow  98 , as shown in FIG.  1 . 
     It is to be understood that the described embodiments of the invention are illustrative only, and that modifications thereof may occur to those skilled in the art. For example, the helical track may be formed on the exterior surface of a shaft or the internal surface of a cavity, while the shaft or cavity may be fixedly coupled to the head or the piston. Accordingly, this invention is not to be regarded as limited to the embodiments disclosed, but is to be limited only as defined by the appended claims herein.