U.S. patent application number 10/942982 was filed with the patent office on 2006-03-23 for helical ground anchor and method of its use.
Invention is credited to Per Alton Dahlstrom.
Application Number | 20060060749 10/942982 |
Document ID | / |
Family ID | 36072928 |
Filed Date | 2006-03-23 |
United States Patent
Application |
20060060749 |
Kind Code |
A1 |
Dahlstrom; Per Alton |
March 23, 2006 |
Helical ground anchor and method of its use
Abstract
A ground anchor system for anchoring a post comprises a base
plate, a housing extending above the base plate, an anchor
extending below the base plate, the anchor comprising a tapered
helix having a thread encircling a tube which tapers inwardly
towards the lower end of the anchor, and a boring tip at the lower
end of the anchor. The tapered helical thread of the anchor firmly
engages with the ground into which it is threaded to provide a
solid support to a post inserted in the housing. Helix taper and
length, and thread taper and pitch may be selected to optimize
retention and lateral support of a post in a particular ground
type.
Inventors: |
Dahlstrom; Per Alton;
(Duncan, CA) |
Correspondence
Address: |
Stephen R. Burri;Miller Thomson LLP
1000 - 840 Howe Street
Vancouver
BC
V6Z 2M1
CA
|
Family ID: |
36072928 |
Appl. No.: |
10/942982 |
Filed: |
September 17, 2004 |
Current U.S.
Class: |
248/545 ;
248/156 |
Current CPC
Class: |
A45F 3/44 20130101 |
Class at
Publication: |
248/545 ;
248/156 |
International
Class: |
A45F 3/44 20060101
A45F003/44 |
Claims
1. A ground anchor system for anchoring a post comprising: a base
plate, a housing extending above the base plate, an anchor
extending below the base plate, the anchor comprising a tapered
helix having a thread encircling a tube which tapers inwardly
towards the lower end of the anchor, and a boring tip at the lower
end of the anchor.
2. The ground anchor system of claim 1 wherein the base plate,
housing, anchor and boring tip are structurally integrated.
3. The ground anchor system of claim 1 wherein the base plate,
housing, anchor and boring tip are manufactured by injection
over-molding onto a metal tube.
4. The ground anchor system of claim 1 wherein the base plate,
housing, anchor and boring tip are manufactured by extrusion.
5. The ground anchor system of claim 1 wherein the base plate,
housing, anchor and boring tip are manufactured by casting.
6. The ground anchor system of claim 1 wherein the upper end of the
helix begins at the base plate.
7. The ground anchor system of claim 1 wherein the helix begins
below the base plate a distance of no greater than 25% of the
combined length of the anchor and boring tip.
8. The ground anchor system of claim 1 wherein the lower end of the
helix ends above the end of the boring tip a distance of no greater
than 50% of the combined length of the anchor and boring tip.
9. The ground anchor system of claim 1 wherein the helix tapers
inwardly towards the lower end of the anchor at a constant angle of
between 1 and 30 degrees relative to the vertical plane.
10. The ground anchor system of claim 1 wherein the helix tapers
inwardly towards the lower end of the anchor at a continuously
increasing angle in the range between 1 and 30 degrees relative to
the vertical plane.
11. The ground anchor system of claim 1 wherein the angular pitch
of the thread is constant and is between 3 and 30 degrees relative
to the horizontal plane.
12. The ground anchor system of claim 1 wherein the thread tapers
from a first width proximal to the tube to a second narrower width
distal to the tube.
13. The ground anchor system of claim 1 wherein the housing
comprises solid walls.
14. The ground anchor system of claim 1 wherein the housing
comprises non-solid walls.
15. The ground anchor system of claim 1 wherein at least one
interior wall of the housing comprises friction enhancing
means.
16. The ground anchor system of claim 1 wherein the friction
enhancing means comprises at least one vertical ridge.
17. The ground anchor system of claim 1 wherein the friction
enhancing means comprises a plurality of fins.
18. The ground anchor system of claim 1 wherein the housing further
comprises post attachment means.
19. The ground anchor system of claim 18 wherein the post
attachment means comprises one or more bolts.
20. The ground anchor system of claim 18 wherein the post
attachment means comprises one or more screws.
21. The ground anchor system of claim 18 wherein the post
attachment means comprises a threaded adaptor lining the housing
for receiving a threaded post.
22. The ground anchor system of claim 1 wherein the housing further
comprises one or more insertable elements to reduce the horizontal
cross-sectional area of the housing.
23. The ground anchor system of claim 1 wherein the boring tip is
crimped.
24. The ground anchor system of claim 1 further comprising an
opening between the housing and the tube of the anchor.
25. The ground anchor system of claim 1 wherein the material used
to manufacture the base plate, housing, anchor and boring tip is a
plastic.
26. The ground anchor system of claim 25 wherein the plastic is a
recycled polyethylene terephthalate.
27. The ground anchor system of claim 25 wherein the plastic is a
dark colour.
28. A ground anchor system for anchoring a post comprising: a base
plate, a housing extending above the base plate, an anchor
extending below the base plate, the anchor comprising a tapered
helix having a thread encircling a tube which tapers inwardly
towards the lower end of the anchor, and a boring tip at the lower
end of the anchor wherein the helix begins at the base plate and
ends above the end of the boring tip a distance of no more than 50%
of the combined length of the anchor and boring tip and tapers
inwardly towards the lower end of the anchor at an angle of between
1 and 30 degrees relative to the vertical plane, the thread has a
constant angular pitch of between 3 and 30 degrees relative to the
horizontal plane and tapers from a first width proximal to the tube
to a second narrower width distal to the tube, and the base plate,
housing, anchor and boring tip are manufactured by injection
over-molding onto a metal tube.
29. A ground anchor system for anchoring a post comprising: a base
plate, a housing extending above the base plate, an anchor
extending below the base plate, the anchor comprising a tapered
helix having a thread encircling a tube which tapers inwardly
towards the lower end of the anchor, and a boring tip at the lower
end of the anchor wherein the helix begins at the base plate and
ends above the end of the boring tip a distance of no more than 50%
of the combined length of the anchor and boring tip and tapers
inwardly towards the lower end of the anchor at an angle of between
1 and 30 degrees relative to the vertical plane, the thread has a
constant angular pitch of between 3 and 30 degrees relative to the
horizontal plane and tapers from a first width proximal to the tube
to a second narrower width distal to the tube, and the base plate,
housing, anchor and boring tip are manufactured by extrusion.
30. A ground anchor system for anchoring a post comprising: a base
plate, a housing extending above the base plate, an anchor
extending below the base plate, the anchor comprising a tapered
helix having a thread encircling a tube which tapers inwardly
towards the lower end of the anchor, and a boring tip at the lower
end of the anchor wherein the helix begins at the base plate and
ends above the end of the boring tip a distance of no more than 50%
of the combined length of the anchor and boring tip and tapers
inwardly towards the lower end of the anchor at an angle of between
1 and 30 degrees relative to the vertical plane, the thread has a
constant angular pitch of between 3 and 30 degrees relative to the
horizontal plane and tapers from a first width proximal to the tube
to a second narrower width distal to the tube, and the base plate,
housing, anchor and boring tip are manufactured by casting.
31. A post anchoring system comprising: a base plate, a housing
extending above the base plate, an anchor extending below the base
plate, the anchor comprising a tapered helix encircling a tube
which tapers inward at its lower end, a boring tip at the lower end
of the anchor, and a post inserted into the housing, wherein the
length of the anchor is at least 25% of the length of the overall
post anchoring system.
32. The post anchoring system of claim 31, wherein the base plate,
housing, anchor, boring tip and post are structurally
integrated.
33. A method of inserting a post anchor comprising the steps of:
vertically positioning the post anchor in a selected location with
the tip of the post anchor in contact with the ground surface,
driving the post anchor by driving means into the ground to a
position in which the thread of the helix of the post anchor is in
contact with the ground surface, placing a lever arm in the housing
of the post anchor, simultaneously applying sufficient downward
pressure and rotational torque to the lever arm to rotate the post
anchor into the ground to a position in which the base plate is in
contact with the ground surface, removing the lever arm, and
positioning and affixing a post into the housing of the post
anchor.
34. The method of inserting a post anchor of claim 33, wherein the
driving means comprises a drive shaft integrated with the lever
arm.
Description
TECHNICAL FIELD OF THE INVENTION
[0001] The present invention relates generally to ground anchors.
In particular, the invention relates to a ground anchor for
securing and installing posts for use in fencing or other
construction.
BACKGROUND OF THE INVENTION
[0002] Several problems arise when securing posts for construction,
such as are used for fences, greenhouses, sheds, etc. in loose,
wet, inaccessible or otherwise difficult ground. Firstly, the
retention of a post in the ground is lessened by variable soil
conditions such as soil compactness, water saturation, and variable
water levels which may reduce the amount of force required to
dislodge a post. Secondly, traditional wooden posts remaining in
wet soils have a limited life span, usually no more than ten years,
as they are susceptible to rot and decay when immersed in a moist
soil environment. Thirdly, installed posts, whether pounded or
reinforced by a concrete pour, are difficult to maintain, extract
or adapt, and are generally non-reusable.
[0003] These problems may be overcome through use of a tapered
helical anchor of durable material such as plastic or corrosion
resistant metal, and a serviceable platform for the maintenance of
the above ground portion of the supporting post structure.
Temporary and seasonal fencing is possible using this durable and
reusable design.
[0004] There are a number of desirable objectives in relation to
screw-type ground anchors. Such anchors should preferably be made
of plastic or other corrosion resistant material, and should be
easy to install, maintain, extract and reuse. For ease of
manufacture, they should be of an integrated design, and preferably
hollow to reduce material costs. For optimal ground entry and post
support, they should ideally provide a notched boring tip, and a
continuous helix which tapers inward toward the base of the anchor
and provides a wide, pitched thread. The anchor should also provide
a secure post mount which is adaptable to a variety of posts.
Existing ground anchors achieve some of these objectives, but with
varying degrees of success.
[0005] It is known to provide a screw-type device for anchoring a
post. Such a device is described in European Patent Patent No.
0542692 to Moore. Moore teaches a helical anchor pile preferably
made of plastic and having a base plate for anchoring of a post to
the top surface of the anchor. The anchor in Moore is directed to
anchoring an otherwise free-standing structure such as a
transmission tower.
[0006] It is also known to provide a screw-type ground anchor for
low stress, temporary installations such as beach umbrellas. Such a
device is described in U.S. Pat. No. 5,046,699 to Perreault. The
anchor in Perreault provides a helix only at the lowermost end of
the anchor. Such a helix is sufficient for temporary installations
designed for easy removal, but would be insufficient for long term
post installations.
[0007] Other helical ground anchors are known. In French Patent No.
2,571,771, Rovera discloses a screw-type ground anchor in which the
anchoring helix does not taper until the lowermost region of the
anchor, and the thread pitch is constant. Pylant, in U.S. Pat. No.
6,412,235, teaches a ground anchor with non-tapered screw threads
only near the tip of the anchor.
SUMMARY OF THE INVENTION
[0008] In one embodiment, the invention comprises a ground anchor
system for anchoring a post comprising a base plate, a housing
extending above the base plate, an anchor extending below the base
plate, the anchor comprising a tapered helix having a thread
encircling a tube which tapers inwardly towards the lower end of
the anchor, and a boring tip at the lower end of the anchor.
[0009] The base plate, housing, anchor and boring tip may be
structurally integrated, and may be manufactured by injection
over-molding onto a metal tube, by extrusion, or by casting.
[0010] The upper end of the helix may begin at the base plate or
below the base plate a distance of no greater than 25% of the
combined length of the anchor and boring tip. The lower end of the
helix may end above the end of the boring tip a distance of no
greater than 50% of the combined length of the anchor and boring
tip.
[0011] The helix may taper inwardly towards the lower end of the
anchor at a constant angle of between 1 and 30 degrees relative to
the vertical plane, or at a continuously increasing angle in the
range between 1 and 30 degrees relative to the vertical plane.
[0012] The angular pitch of the thread may be constant and may be
between 3 and 30 degrees relative to the horizontal plane, or the
thread mat taper from a first width proximal to the tube to a
second narrower width distal to the tube.
[0013] The housing may comprise solid walls or non-solid walls. At
least one interior wall of the housing may comprise friction
enhancing means. The friction enhancing means may be at least one
vertical ridge or a plurality of fins. The housing may further
comprise post attachment means. The post attachment means may be
one or more bolts, one or more screws, or a threaded adaptor lining
the housing for receiving a threaded post. The housing further may
comprise one or more insertable elements to reduce the horizontal
cross-sectional area of the housing.
[0014] The boring tip may be crimped, and there may be an opening
between the housing and the tube of the anchor. The material used
to manufacture the base plate, housing, anchor and boring tip may
be a plastic. The plastic may be a recycled polyethylene
terephthalate, and it may be a dark colour.
[0015] In another embodiment, the invention comprises a ground
anchor system for anchoring a post comprising a base plate, a
housing extending above the base plate, an anchor extending below
the base plate, the anchor comprising a tapered helix having a
thread encircling a tube which tapers inwardly towards the lower
end of the anchor, and a boring tip at the lower end of the anchor,
wherein the helix begins at the base plate and ends above the end
of the boring tip a distance of no more than 50% of the combined
length of the anchor and boring tip and tapers inwardly towards the
lower end of the anchor at an angle of between 1 and 30 degrees
relative to the vertical plane, the thread has a constant angular
pitch of between 3 and 30 degrees relative to the horizontal plane
and tapers from a first width proximal to the tube to a second
narrower width distal to the tube, and the base plate, housing,
anchor and boring tip are manufactured by injection over-molding
onto a metal tube.
[0016] In yet another embodiment the invention comprises a ground
anchor system for anchoring a post comprising a base plate, a
housing extending above the base plate, an anchor extending below
the base plate, the anchor comprising a tapered helix having a
thread encircling a tube which tapers inwardly towards the lower
end of the anchor, and a boring tip at the lower end of the anchor,
wherein the helix begins at the base plate and ends above the end
of the boring tip a distance of no more than 50% of the combined
length of the anchor and boring tip and tapers inwardly towards the
lower end of the anchor at an angle of between 1 and 30 degrees
relative to the vertical plane, the thread has a constant angular
pitch of between 3 and 30 degrees relative to the horizontal plane
and tapers from a first width proximal to the tube to a second
narrower width distal to the tube, and the base plate, housing,
anchor and boring tip are manufactured by extrusion.
[0017] In still another embodiment, the invention comprises a
ground anchor system for anchoring a post comprising a base plate,
a housing extending above the base plate, an anchor extending below
the base plate, the anchor comprising a tapered helix having a
thread encircling a tube which tapers inwardly towards the lower
end of the anchor, and a boring tip at the lower end of the anchor
wherein the helix begins at the base plate and ends above the end
of the boring tip a distance of no more than 50% of the combined
length of the anchor and boring tip and tapers inwardly towards the
lower end of the anchor at an angle of between 1 and 30 degrees
relative to the vertical plane, the thread has a constant angular
pitch of between 3 and 30 degrees relative to the horizontal plane
and tapers from a first width proximal to the tube to a second
narrower width distal to the tube, and the base plate, housing,
anchor and boring tip are manufactured by casting.
[0018] In yet another embodiment, the invention comprises a post
anchoring system comprising a base plate, a housing extending above
the base plate, an anchor extending below the base plate, the
anchor comprising a tapered helix encircling a tube which tapers
inward at its lower end, a boring tip at the lower end of the
anchor, and a post inserted into the housing, wherein the length of
the anchor is at least 25% of the length of the overall post
anchoring system.
[0019] In still a further embodiment, the invention comprises a
method of inserting a post anchor comprising the steps of
vertically positioning the post anchor in a selected location with
the tip of the post anchor in contact with the ground surface,
driving the post anchor by driving means into the ground to a
position in which the thread of the helix of the post anchor is in
contact with the ground surface, placing a lever arm in the housing
of the post anchor, simultaneously applying sufficient downward
pressure and rotational torque to the lever arm to rotate the post
anchor into the ground to a position in which the base plate is in
contact with the ground surface, removing the lever arm, and
positioning and affixing a post into the housing of the post
anchor.
[0020] The driving means may comprise a drive shaft integrated with
the lever arm.
[0021] Other aspects of the invention will be appreciated by
reference to the description of the preferred embodiment which
follows and to the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The invention will be described by reference to the
preferred embodiment and the drawings thereof in which:
[0023] FIG. 1 is a perspective view of the ground anchor, according
to the invention;
[0024] FIG. 2 is a plan view of the ground anchor, according to the
invention;
[0025] FIG. 3 is a cross-sectional view through line 3-3 of FIG. 2;
and
[0026] FIG. 4 is a perspective view of an installation, according
to the invention.
DETAILED DESCRIPTION OF BEST MODE AND PREFERRED EMBODIMENT OF THE
INVENTION
[0027] As shown if FIGS. 1, 2 and 3, an integrated ground anchor
and post mount housing device 2 comprises a housing 4 adjacent a
base plate 6, the base plate adjacent an anchor segment. The anchor
segment is a hollow tube 8 incorporating a helix 10 extending along
a portion of its length, and a boring tip 12 at its lowermost end.
The housing provides support for a post or other upright inserted
therein. The base plate 6 connects the housing 4 to the anchor
segment and defines the extent of insertion of the anchor into the
ground. The anchor segment helix 10 has a wide and tapered thread
14 extending most of its length. The boring tip 12 is narrowed,
crimped or cut to assist in the loosing of the soil for anchor
segment insertion.
[0028] The length of the anchor segment preferably is at least 25%
of the above ground height of the supported post. The hollow tube 8
may taper inwardly from the base plate towards the boring tip 12.
Referring now to FIG. 2, the helical portion preferably begins at a
distance a above the bottom end of the anchor of between 10% and
25% of the total length of the embedded portion of the anchor. The
helix is continuous and has a taper b which may be fixed or may
vary between 1 and 20 degrees relative to the vertical plane,
increasing in angle from the terminus to the base plate. The helix
preferably terminates at a distance c below the base plate. The
angular pitch d of the thread 14 is preferably a constant angle of
between 3 and 30 degrees relative to the horizontal plane. As in a
conventional screw, the thread preferably is tapered, having a
thicker width proximal to the central vertical axis of the ground
anchor and narrowing distal to the vertical axis.
[0029] The tapered helical thread of the anchor firmly engages with
the ground into which it is threaded to provide a solid support to
a post inserted in the housing. Helix taper and length, and thread
taper and pitch may be selected to optimize retention and lateral
support of a post in a particular ground type.
[0030] The base plate preferably is of a design and dimensions
sufficient for ensuring the lateral stability of the anchoring
system and of sufficient strength to support the housing and anchor
segments. The housing preferably provides support to the post and
surrounds the lower end of the post on all sides for a distance of
at least 10% of the overall length of the post. The housing may
have solid walls 18, as shown in FIG. 1, or non-solid walls. For
example, as shown in FIG. 2, the non-solid walls 20 may have a
plurality of openings to reduce material requirements. One or more
inserts 22 may be used for the accommodation of posts having a
diameter smaller diameter posts. The inserts may be placed between
the post and the housing walls to ensure a close fit.
[0031] Post support in the housing may be enhanced by one or more
of the following mechanisms: [0032] 1. bolts or screws may be used
to secure the post within the housing; [0033] 2. a threaded adaptor
may be disposed on the base plate to permit the post to be screwed
onto the base plate following anchor installation; [0034] 3. a
plurality of fins may be integrated into the interior surface of
the housing; [0035] 4. the post may be selected or machined to fit
snugly in the housing to enhance friction between the surfaces of
contact of the post and the housing; [0036] 5. inserts may be
fitted into the housing to permit the securing of smaller
posts.
[0037] In one embodiment, the post may be molded or extruded
integrally with the anchor to create a monolithic post and anchor
structure.
[0038] To permit egress of water which may collect in the housing,
an opening 24 may be provided through the base plate 6 between the
housing 4 and the hollow tube 8 of the anchor segment to allow for
drainage of water. This opening will also permit the escape of air
displaced by insertion of the post into the housing.
[0039] Preferably, the ground anchor device is manufactured by
extrusion, direct-injection molding or over-molding from plastic or
corrosion-resistant metals such as aluminum. The hollow post design
facilitates entry into the soil, adds to stability of the anchor in
the ground, allows for drainage of water and equalisation of air
pressure, and reduces material costs.
[0040] The helix of the ground anchor permits the post to be
reused, and provides for increased lateral stability and retention,
particularly in loose soils. The presence of a wide thread on the
helix provides greater stability to the anchor by increasing the
surface area which is contact with the soil. The boring tip loosens
soil to facilitate entry of the helical thread into the ground.
[0041] An adaptable housing allows for different types of posts to
be used in conjunction with the ground anchor, and facilitates
maintenance and adaptation of the above-ground portion of the post
as necessary. The base plate provides strength to the physical
connection between the housing and the helical anchor and increases
the lateral stability of the anchor in the ground.
[0042] According to one embodiment of the method of the invention,
a post may be anchored into the ground according to the following
steps: [0043] 1. the boring tip of the anchor segment is driven or
pushed into the ground until the edge of the first thread of the
helix makes contact with the ground; [0044] 2. a lever arm or drive
shaft is placed into the housing; [0045] 3. downward pressure and
torque are applied to the lever arm or drive shaft to screw the
anchor segment into the ground until the base plate makes contact
with the ground; [0046] 4. the lever arm or drive shaft is removed
from the housing; and [0047] 5. a post is placed into the housing
and affixed therein.
[0048] As shown in FIG. 4, a plurality of ground anchor and post
mount housing devices 2 may be screwed into the ground surface
until the base plates 6 are at the surface of the ground. A post 26
may be inserted into the housing 4 of each anchor. In one
embodiment, anchored posts may be joined by rails to form a fence
which is easily removable and reusable.
[0049] It will be appreciated by those skilled in the art that
other variations of the preferred embodiment may also be practised
without departing from the scope of the invention.
* * * * *