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 
     1. Field of the Invention 
     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. 
     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. 
     The present invention in one aspect is directed to vibration dampers for poles capable of reducing first mode natural frequency vibrations. 
     2. Related Art 
     The prior art is replete with devices and methods intended to reduce pole vibration as exemplified by the following discussed prior art patents. 
     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. 
     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. 
     Kemeny U.S. Pat. No. 6,035,981 discloses a complicated broadband passive mass damper intended for use on machinery or other equipment. 
     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. 
     Phillips et al. U.S. Pat. No. 5,682,069 discloses a vibration damping assembly mounted on a strut about which the device surrounds. 
     Hamada et al. U.S. Pat. No. 5,593,144 discloses a vibration damping device mounted on a drive shaft. 
     Knodo et al. U.S. Pat. No. 4,736,701 discloses a variety of devices for attachment to the upper end of a mast. 
     Lehmann et al. U.S. Pat. No. 4,640,216 is directed to a vibration damping assembly for a periscope. 
     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. 
     Reed U.S. Pat. No. 3,568,803 discloses a vibration damping device attached to the upper end of a mast. 
     Reutlinger U.S. Pat. No. 3,382,629 discloses a vibration damping assembly attached to a mast or pole. 
     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. 
     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. 
     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 
     The primary object of the present invention is the provision of pole vibration dampers for reducing first harmonic mode vibrations. 
     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. 
     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. 
     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 
       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: 
         FIG. 1  is a front elevation view of a light pole on which the preferred embodiment first harmonic mode vibration damper apparatus is positioned; 
         FIG. 2  is a perspective view of a of a first half-portion housing component of the first harmonic mode vibration damper apparatus; 
         FIG. 3  is a top plan view of a second half-portion housing component of the first harmonic mode vibration damper apparatus; 
         FIG. 4  is a front elevation view of the second half-portion housing component of  FIG. 3 ; 
         FIG. 5  is a rear elevation view of the second half-portion housing component of  FIG. 3 ; 
         FIG. 6  is a right side elevation view of the second half-portion housing component of  FIG. 3 ; 
         FIG. 7  is a sectional view taken along line  7 — 7  of  FIG. 3 ; 
         FIG. 8  is a sectional view taken along line  8 — 8  of  FIG. 3 ; 
         FIG. 9  is an enlarged view of the encircled portion  9  in  FIG. 3 ; 
         FIG. 10  is an enlarged view of the encircled portion  10  in  FIG. 3 ; 
         FIG. 11  is an enlarged view of the encircled portion  11  in  FIG. 3 ; 
         FIG. 12  is a section view taken along line  12 — 12  of  FIG. 3 ; 
         FIG. 13  is an enlarged view of the encircled portion  13  in  FIG. 3 ; 
         FIG. 14  is an enlarged view of the encircled portion  14  in  FIG. 3 ; 
         FIG. 15  is a section view taken along line  15 — 15  of  FIG. 3 ; 
         FIG. 16  is a top plan view of the preferred embodiment first harmonic mode vibration damper with the top cover components removed; 
         FIG. 17  is a front elevation view of the preferred embodiment of  FIG. 16 ; 
         FIG. 18  is a top plan view of the preferred embodiment of  FIG. 16  with the top cover components in position; 
         FIG. 19  is a perspective view of the preferred embodiment with the cover components removed; and 
         FIG. 20  is a perspective view of the cover components. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     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. 
     The preferred embodiment of the invention comprises a first harmonic mode vibration damper apparatus  20 , 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 first harmonic mode vibration damper apparatus  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. 
     The primary components of the first harmonic mode vibration damper apparatus  20  comprise first and second housing component half-portions  22  and  24  respectively each of which is identical to the other and 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 have a prime mark (′) added are-primed for the sake of clarity. 
     First housing component half-portion  22  has a vertical height of three (3) inches and includes an inner partial cylinder sleeve surface  26  ( FIG. 2 ) of an inner partial cylinder sleeve  26 S having a center of curvature C and a radius of three (3) inches. Surface  26  blends into an inner planar surface  28  of a first planar panel plate  25  having an outer end terminating at a first outer 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 an inner juncture lug  27  connected to the inner end of a second planar panel plate  30 . The outer end of the second planar panel plate  30  terminates in a second 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 . Second outer connector is also connected to one end of an outer partial cylinder outer sleeve  34  having an inner surface  36  having a radius of approximately eight (8) inches. Outer partial cylinder sleeve  34  has a center of curvature which is coextensive with the center of curvature C of the inner partial cylinder surface  26 . The opposite end of outer partial cylinder sleeve  34  merges into the first outer connector lug  29  as best shown in  FIGS. 2 and 16 . 
     Second housing component half-portion  24  has a vertical height of three (3) inches and includes an inner partial cylinder sleeve surface  26 ′ ( FIG. 3 ) of an inner partial cylinder sleeve  26 S′ having a radius of three (3) inches. Surface  26 S′ blends into an inner planar surface  28 ′ of a first planar panel plate  25 ′ having an outer end terminating at a first outer connector lug  29 ′ having threaded bore openings  31 ′ as shown in  FIG. 5 . The opposite end of the inner partial cylinder surface  26 ′ terminates at an inner juncture lug  27 ′ connected to the inner end of a second planar panel plate  30 ′. The outer end of the second panel plate  30 ′ terminates at a second outer connector lug  32 ′ which has smooth bore holes  58 ′ usable for connecting the second housing component half-portion  24  to the first outer connector lug  29  of first housing component half-portion  22 . Second outer connector lug  32 ′ is also connected to one end of an outer partial cylinder sleeve  34 ′ having an inner surface  36 ′ having a radius of approximately eight (8) inches. Outer partial cylinder sleeve  34 ′ has a center of curvature coextensive with the center of curvature C of the inner partial cylinder surface  26 ′. The opposite end of outer partial cylinder sleeve  34 ′ merges into connector lug portion  29 ′ as best shown in  FIG. 3 . 
     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 respectively connected to housing component half-portions  22  and  24  by metal screws S and  5 ′ passing through apertures  223  and  223 ′ provided in cover portions  222  and  224 . Screws S and  5 ′ are rotated into threaded bores  250  and  250 ′ respectively provided in housing component half-portions  22  and  24  to effect complete closure of the weight retaining chambers so as to prevent damping weights  48  and  48 ′ from escaping from their respective weight receiving chambers. 
     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.