Patent Publication Number: US-6334281-B1

Title: Ground anchor with downward biased compression cap

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of co-pending application Ser. No. 09/573,355, filed May 17, 2000, titled Ground Anchor with Self-aligning Compression Cap. 
    
    
     FIELD OF THE INVENTION 
     This invention relates in general to anchors that are bored into the ground and more specifically to a ground anchor having a cap for compressing soil above an auger wherein the cap is downward biased so as to still provide compression during strain on the anchor and, preferably also, wherein the cap can tilt so as to align with the contour of the grade. 
     BACKGROUND OF THE INVENTION 
     Ground anchors of the auger type tend to loosen the soil as the auger is screwed into the earth. This tends to make the anchor shaft less stable. Particularly, the upper end of the anchor shaft may be able to move back and forth laterally in the loosened soil and thereby loosen the anchor such that the anchor becomes ineffective. Our above-identified co-pending application, teaches the use of a compression cap on the upper end of the shaft. The compression cap is pulled against the top of the disturbed soil by the auger action and bears against and compresses the soil that has been disturbed by the auger. This soil compaction greatly increases the stability of the upper end of the anchor shaft. However, in conditions of large fluctuating forces on anchor lines, such as encountered during a hurricane or tornado, anchors pull out at a undesirable rate. 
     Accordingly, there has been a need for an improved ground anchor. 
     SUMMARY OF THE INVENTION 
     The invention is a ground anchor for boring in the soil, and it generally includes an elongate shank having an auger on its lower end and a attachment mechanism on its upper end for attachment of anchor lines, a compression cap, and biasing means, such as a spring, operating between the upper end of the shank and the compression cap for biasing the cap in a downward direction so as to compress soil between the cap and the auger. 
     The compression cap is a generally disk-shaped plate of uniform thickness having an aperture freely journaling it on the shank above the soil such that said plate can freely tilt through a tilt angle to align with the surface of the soil. Preferably, a side slot provides entry of the shaft to the central aperture. 
     The cap has a generally planar downward facing surface for compressing soil between the cap and the auger blades. Preferably, the cap has peripheral side walls extending upwards or downwards from the perimeter of the plate for bearing against the soil for presenting a larger side surface area than the plate for preventing lateral movement. 
     The biasing means may be one or more springs. Coil, leaf or torsion springs may be used. The spring biases the cap in a downward direction so that soil between the cap and the auger remains compacted at all times. This compacted soil helps prevent lateral movement of shaft  21  and bears laterally outward to prevent upward movement of the auger. 
     Other features and many attendant advantages of the invention will become more apparent upon a reading of the following detailed description together with the drawings wherein like reference numerals refer to like parts throughout. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a perspective view of a first embodiment of the ground anchor of the invention. 
     FIG. 2 is an enlarged side elevation view of the anchor of FIG. 1 in the ground further including anchor bolts and straps. 
     FIG. 3 is an enlarged bottom perspective view of an alternate compression cap. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference now to the drawings, and first particularly to FIGS. 1 and 2 thereof, FIG. 1 is a perspective view of a first embodiment of the ground anchor  10  of the invention; FIG. 2 is an enlarged side elevation view of the anchor of FIG. 1 in the ground, such as soil  90 , further including anchor lines  48  and tensioning bolts  45 . 
     Ground anchor  10  generally includes a shank  20 , a compression cap  60 , such as disk cap  60 A, and biasing means, such as a spring, such as coil spring  50 , operating between the upper end  40  of shank  20  and cap  60  for biasing cap  60  in a downward direction. Shank  20  is an elongate shaft  21 , such as a rod or pipe of metal, such as steel, having a longitudinal axis  22 . Shank  20  includes a lower end, such as boring end  30 , and an upper end  40  including attachment means  41 . Boring end  30  includes a tip  39  and auger means,  32 , such as a helical blade  34 , for boring in soil  90 . Auger means  32  shown is a pair of helical blades  34  attached, such as by any suitable means, such as welding, to shaft  21 . Alternately, auger  32  may be any means capable of boring shank into soil  90 . Blades  34  have a maximum radius. Thus, as blades  34  bore in soil  90 , soil  90  is loosened over a circle of known maximum diameter, that is, a diameter of twice the maximum radius. 
     Attachment means  41  on upper end  40  of shank  20  includes attachment bracket  42  for attachment of one or more anchor lines  48 . Anchor lines  48  have a lower end  49  wrapped on a tensioning bolt  45  as is well-known in the art. Shank  20  is shown bored into soil  90  such that the tension forces in anchor lines  48  tend to pull upper end  40  upwards and sideways toward the object anchored. 
     Compression cap  60  includes a generally disk-shaped plate  62  of generally uniform thickness and having a perimeter  63 . Cap  60  includes an aperture, such as central aperture  65  freely journaling plate  62  on shank  20  above soil  90  such that plate  62  can move longitudinally along shaft  21 , and preferably, also such that cap  60  can tilt through a tilt angle, such as of at least seven degrees and preferably of about ten to fifteen degrees. Thus, preferably, aperture  65  is larger than the cross-sectional area of shaft  21 . Cap  60  includes a generally planar downward facing surface  70  for compressing soil  90  between cap  60  and auger means  32 . Preferably, compression cap  60  has a radius approximating that of the maximum radius of the blades  34 . 
     FIG. 3 is an enlarged bottom perspective view of an alternate compression cap  60 , slotted cap  60 B. Slotted cap  60 B is similar to disk cap  60 A, as described above, but includes a radial slot  66  for providing side entry of shaft  21  to an aperture, such as central aperture  65  such that cap  60 B can easily be attached to shaft  21  after shaft  21  has been bored most of the way into soil  90 . In this manner, cap  60 B is not in the way during boring. 
     Cap  60  may includes side wall means, such as side wall  64 , extending upwards or downwards (as shown) from perimeter  63  of plate  62  for presenting a larger side surface area than plate  62  to aid in preventing lateral movement of cap  60  and shaft through soil  90 . 
     Spring  50  operating between upper end  40  of shank  20 , such as between attachment bracket  42 , and cap  60  for biasing cap  60  in a downward direction so as to compress soil  90  between cap  60  and auger blades  34 . Spring  50  is a single coil having a central aperture receiving shaft  21 . Shaft  21  stabilizes the single spring  50  and spring  50  does not require other attaching means. Although a single coil spring  50  is shown and described, other biasing means are contemplated. For example, a plurality of coil springs may be used. The springs may have a common central aperture or may be spaced from shaft  21 . Other types of springs, such as torsion or leaf springs may be used. Preferably, the biasing means can be applied after anchor  10  is bored into soil  90 . For example, the coils of spring  50  may be spaced so that spring  50  may be threaded over shaft  21 . A plurality of springs may be placed between attachment bracket  42  and cap  60  after boring. The single spring or multiple springs allow cap  60  to tilt so as to align with surface  91  of soil  90 . 
     As an example of a preferred use, a shank  20  with no spring  50  and no cap  60  bored in soil  90  until the auger blades  34  are under soil  90  or until upper end  40  nears soil surface  91 . Then, cap  60 , such as cap  60 B, is slid onto shaft  21  just above soil surface  91  and rested on soil surface  91  so as to align with the contour of the grade. Then, spring  50  is threaded on shaft  51  and rested on cap  60 B. Shank  20  is then bored into soil  90  until spring  50  is compressed sufficiently so as to remain compressed as soil  90  further compresses over time. The constant downward biasing of compression cap  60  keeps the soil compressed so as to prevent lateral movement of shaft  21  and also causes the compressed soil  90  under cap  60  to bear against the side wall of the augered hole and thereby act as a plug preventing upward movement of augers  34 . 
     Having described the invention, it can be seen that it provides a very convenient apparatus for efficient and reliable ground anchoring. 
     Although particular embodiments of the invention have been illustrated and described, various changes may be made in the form, composition, construction, and arrangement of the parts herein without sacrificing any of its advantages. Therefore, it is to be understood that all matter herein is to be interpreted as illustrative and not in any limiting sense, and it is intended to cover in the appended claims such modifications as come within the true spirit and scope of the invention.