Abstract:
A pole vibration damping means includes an annular housing with internal radial pole encircling chambers in which lead spheres are provided for effecting damping of first mode harmonic vibrations with the assembly being attached to the upper end portion of the pole and operating in conjunction with a pole vibration damping device mounted medially for damping second harmonic mode vibrations.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. FIELD OF THE INVENTION  
         [0002]     The present invention relates to a vibration damping apparatus and methods. More specifically, the invention relates to vibration damping apparatus and methods for reducing wind induced vibration of light poles, flag poles and the like.  
         [0003]     Light poles and similar devices are subject to wind induced vibrations which can result in costly and hazardous failures of such structures. Many parameters including pole geometry and materials, wind speed, wind gust frequency and velocity are involved in effecting pole vibration. For many years those of skill in the art were of the belief that second harmonic mode vibrations were solely responsible for structural failures of poles and vibration dampers such as that shown in applicant&#39;s U.S. Pat. No. 3,612,222 were designed so as to reduce second harmonic mode vibration. Second harmonic mode vibration of poles is generally considered to be of approximately four cycles of vibration per second. However, within recent years a number of pole failures have occurred which were not caused by second harmonic mode vibrations but were resultant from first harmonic mode vibrations which occurred at a frequency of approximately one vibration cycle per second.  
         [0004]     The present invention in one aspect is directed to vibration dampers for poles capable of reducing first mode natural frequency vibrations.  
         [0005]     2. RELATED ART  
         [0006]     The prior art is replete with devices and methods intended to reduce pole vibration as exemplified by the following discussed prior art patents.  
         [0007]     Applicant&#39;s earlier U.S. Pat. No. 3,612,222 discloses a pole-mounted second mode natural frequency vibration damping assembly employing a metal rod loosely fitted in a tubular member attached to the pole.  
         [0008]     Feldberg U.S. Pat. No. 6,234,286 purports to be an improvement over applicant&#39;s earlier U.S. Pat. No. 3,612,222 with respect to which it differs only in a minor manner relating to the attachment of the device to a pole.  
         [0009]     Kemeny U.S. Pat. No. 6,035,981 discloses a complicated broadband passive mass damper intended for use on machinery or other equipment.  
         [0010]     Aida et al. U.S. Pat. No. 5,896,961 discloses a dynamic vibration absorber mounted on a light pole by a variety of magnetic devices.  
         [0011]     Phillips et al. U.S. Pat. No. 5,682,069 discloses a vibration damping assembly mounted on a strut about which the device surrounds.  
         [0012]     Hamada et al. U.S. Pat. No. 5,593,144 discloses a vibration damping device mounted on a drive shaft.  
         [0013]     Knodo et al. U.S. Pat. No. 4,736,701 discloses a variety of devices for attachment to the upper end of a mast.  
         [0014]     Lehmann et al. U.S. Pat. No. 4,640,216 is directed to a vibration damping assembly for a periscope.  
         [0015]     Buckley U.S. Pat. No. 4,350,233 discloses a vibration damping device provided internally of a pole or the like effecting first harmonic mode vibration damping.  
         [0016]     Reed U.S. Pat. No. 3,568,803 discloses a vibration damping device attached to the upper end of a mast.  
         [0017]     Reutlinger U.S. Pat. No. 3,382,629 discloses a vibration damping assembly attached to a mast or pole.  
         [0018]     Nishioka et al. U.S. Pat. No. 3,259,212 discloses a pole vibration damping device mounted on the outer end of a curved pole.  
         [0019]     Chen U.S. Pat. No. 3,245,177 is directed to a vibration damping device for reducing vibrations of a chimney or the like by the use of porous, loose fill material and liquid.  
         [0020]     Chen U.S. Pat. No. 3,174,589 is similar to the above-noted U.S. Pat. No. 3,245,177.  
       SUMMARY OF THE INVENTION  
       [0021]     The primary object of the present invention is the provision of pole vibration dampers for reducing first harmonic mode vibrations.  
         [0022]     A further object of the present invention is the provision of pole first mode vibration dampers capable of operating in conjunction with second harmonic mode vibration dampers of the same pole.  
         [0023]     The present invention achieves the foregoing objects by the provision of an annular hollow housing having an axially positioned cylindrical opening dimensioned to matingly fit over a pole upper end portion. The annular housing has a an annular interior chamber which is divided into a plurality of discreet chambers extending about the entire periphery of the housing with each chamber enclosing a single spherical lead weight. The weights act in harmony to reduce first mode harmonic vibration. The first mode harmonic vibration damper acts in conjunction with a second mode vibration damper provided in the mid-portion of the pole so as to reduce vibration and preclude structural failure caused by either first or second mode vibration.  
         [0024]     Other objects, features and advantages of the present invention will be apparent to those skilled in the art upon a reading of this specification including the accompanying drawings.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0025]     The invention is better understood by reference to the following Detailed Description of the Preferred Embodiments with reference to the accompanying drawing figures, in which like reference numerals refer to like elements throughout, and in which:  
         [0026]      FIG. 1  is a front elevation view of a light pole on which the preferred embodiment first harmonic mode damping apparatus is positioned;  
         [0027]      FIG. 2  is a perspective view of a preferred embodiment of a half-portion housing of the first harmonic mode vibration damping device;  
         [0028]      FIG. 3  is a top plan view of a half-portion housing of  FIG. 2 ;  
         [0029]      FIG. 4  is a front elevation view of the half-portion housing of the  FIG. 3 ;  
         [0030]      FIG. 5  is a rear elevation view of the half-portion housing of  FIG. 3 ;  
         [0031]      FIG. 6  is a right side elevation view of the half-portion housing of  FIG. 3 ;  
         [0032]      FIG. 7  is a sectional view taken along line  7 - 7  of  FIG. 3 ;  
         [0033]      FIG. 8  is a sectional view taken along line  8 - 8  of  FIG. 3 ;  
         [0034]      FIG. 9  is an enlarged view of the encircled portion  9  in  FIG. 3 ;  
         [0035]      FIG. 10  is an enlarged view of the encircled portion  10  in  FIG. 3 ;  
         [0036]      FIG. 11  is an enlarged view of the encircled portion  11  in  FIG. 3 ;  
         [0037]      FIG. 12  is a section view taken along line  12 - 12  of  FIG. 3 ;  
         [0038]      FIG. 13  is an enlarged view of the encircled portion  13  in  FIG. 3 ;  
         [0039]      FIG. 14  is an enlarged view of the encircled portion  14  in  FIG. 3 ;  
         [0040]      FIG. 15  is a section view taken along line  15 - 15  of  FIG. 3 ;  
         [0041]      FIG. 16  is a top plan view of the preferred embodiment first harmonic mode vibration damper with the top cover components removed;  
         [0042]      FIG. 17  is a front elevation view of the preferred embodiment of  FIG. 16 ;  
         [0043]      FIG. 18  is a top plan view of the preferred embodiment of  FIG. 16  with the top cover components in position;  
         [0044]      FIG. 19  is a perspective view of the preferred embodiment with the cover components removed; and  
         [0045]      FIG. 20  is a perspective view of the cover components  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0046]     In describing the following embodiments of the present invention illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the invention is not intended to be limited to the specific terminology so selected, and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner to accomplish a similar purpose.  
         [0047]     The preferred embodiment  20  of the invention comprises a first harmonic mode vibration damper which in use is mounted on a pole P in an upper position thereof as shown in  FIG. 1 . It should be noted that the preferred embodiment  20  is mounted at the upper end of pole P adjacent a mounting fitting in the form of a pipe  121  or the like of conventional construction and to which a light or other device is conventionally mounted when the pole is in use. It should also be noted that a conventional second harmonic mode vibration damper  21  of the type disclosed in U.S. Pat. No. 3,612,222 is mounted in the mid-portion of pole P.  
         [0048]     The primary components of the preferred embodiment  20  comprise first and second housing component half-portions  22  and  24  respectively each of which is formed of cast aluminum. The first housing component half-portion  22  and second housing component half-portion  24  are identical and are associated together to form a unitary housing structure  54  as shown in  FIGS. 16 and 19 . The first housing component half-portion  22  will be described in detail and it should be understood that such description is equally applicable to the second housing component half-portion  24 . The numerical designators applied to second housing component half-portion  24  in the drawings correspond to those of first housing component half-portion  22  but are primed for the sake of clarity.  
         [0049]     Housing component half-portion  22  has a vertical height of three (3) inches and includes an inner partial cylinder surface  26  ( FIG. 2 ) having a radius of approximately three (3) inches which blends into an inner planar surface  28  of a first panel plate  25  having an outer end terminating at a connector lug  29  having threaded bore openings  31  as shown in  FIG. 2 . The opposite end of the inner partial cylinder surface  26  terminates at a juncture lug  27  connected to the inner end of a second panel plate  30 . The outer end of the second panel plate  30  terminates in an outer connector lug  32  which has smooth bore holes  58  usable for connecting the first housing component half-portion  22  to the connector lug  29 ′ of second housing component half-portion  24  in a manner to be discussed. Connector lug  32  is also connected to one end of an outer partial cylindrical outer sleeve  34  having an inner surface  36  having a radius of eight (8) inches. Sleeve  34  is of cylindrical configuration and having a center of curvature coextensive with the center of curvature of the inner partial cylinder surface  26 . The opposite end of outer sleeve  34  merges into the connector lug portion  29  as best shown in  FIGS. 2 and 16 .  
         [0050]     Internal positioning panels  38  and  40  extend chordally relative to sleeve  34  and surface  26  internally of the first housing component half-portion  22  between the inner surface of the outer partial cylindrical sleeve  34  and the outer surface of the inner partial cylinder surface  26  so as to divide the interior of first half-housing component  22  into damping weight receiving chambers  42 ,  44  and  46  each having floor portions  50  and walls oriented 60° relative to each other. A spherical damping weight  48  formed of lead and having a diameter of approximately 2.1875 inches is provided in each weight receiving chamber. The damping weights  48  could also be formed of other heavy metal material or could comprise lead or other metal spheres covered with a polyurethane coating.  
         [0051]     The upper and lower threaded apertures  31  in lug portion  29  of first housing component half-portion  22  are alignable with bore holes  58 ′ in connector lug  32 ′ ( FIG. 19 ) of second housing component half-portion  24  so that machine screws  60  can be inserted through bore holes  58 ′ and into threaded apertures  31  for effecting connection of the aligned components  29  and  32  as shown in  FIG. 16 .  
         [0052]     Similarly, bore holes  58  in connector lug  32  of portion  22  are alignable with threaded apertures  31 ′ in the lug portion  29 ′ of the second housing component half-portion  24 . Tightening of the aforementioned machine screws acts to clamp the annular composite assembly consisting of items  22  and  24  as shown in  FIG. 16  of the pole P positioned between surfaces  26  and  26 ′ in an obvious manner.  
         [0053]     Completion of the mounting of the assembly on the cylindrical upper end surface of the pole is effected by positioning of metal cover portions  222  and  224  on top of half-portions  22  and  24 . The cover portions  222  and  224  are then respectively connected to half-portions  22  and  24  structure by metal screws passing through apertures  223  provided therein to enter threaded bores  250  in the half-portions. The completed assembly is then mounted on the cylindrical upper end surface of the pole.  
         [0054]     Modifications and variations of the above-described embodiments of the present invention are possible, such as different dimensions and equivalent structure as appreciated by those skilled in the art in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims and their equivalents, the invention may be practiced otherwise than as specifically described.