A. Field of the Invention
The impact sand anchor of the invention provides an anchor location in sand. As used in this document, the term ‘sand’ means beach sand and also means any other suitable soil or granular material into which the sand anchor may be driven. The sand anchor may support a beach umbrella, fishing rods, nets for game play or any other desired object on the sand. The impact sand anchor allows attachment of the beach umbrella or other object quickly and with little effort, making the impact sand anchor suitable for use by persons having limited strength. The impact sand anchor may be integral to a beach umbrella or other object to be supported. Alternatively, the impact sand anchor may be stand-alone. The Invention also relates to a method for supporting a beach umbrella using the impact sand anchor and a kit of parts including the impact sand anchor and a beach umbrella.
B. Statement of the Related Art
The simplest apparatus to support an umbrella on a beach or in other sandy soil is the bare pole of the umbrella. A user inserts the end of the bare pole in the sand to a suitable depth, say, 12 inches. The mass of the sand into which the bare pole is inserted and the friction force of the sand grains against one another resist blow-over of the bare pole and hence the umbrella. The friction force of the sand grains against the bare pole resists pull-out of the pole. As used in this document, the term ‘blow-over’ or ‘pull over’ refers to a force applied to a pole or umbrella generally parallel to the surface of the ground, as by a wind blowing normal to the longitudinal axis of the pole supporting the umbrella. As used in this document, the term ‘pull out’ refers to a force applied along the longitudinal axis of the pole in a direction away from the ground.
In a typical wind situation on a beach, a wind blows parallel to the surface of the ground and pushes upon an umbrella canopy supported by a bare umbrella pole. The umbrella pole is oriented initially so that its longitudinal axis is generally normal to the surface of the ground and to the wind. The force of the wind acting on the umbrella causes the umbrella pole to displace the sand into which the umbrella pole is buried, allowing the umbrella to tilt. As the umbrella pole tilts away from the wind, a component of the force applied by the wind to the umbrella canopy becomes a pull-out force along the longitudinal axis of the umbrella pole. For the same wind speed, the greater the tilt of the umbrella, the greater the pull-out force applied by the wind to the umbrella pole.
The resistance to pull-out of a partially buried bare pole is provided only by the friction of the sand grains against the buried shaft of the pole, and hence a bare umbrella pole offers little pull-out resistance. If the wind is successful in pulling the umbrella from the sand, the umbrella and its pole may tumble downwind, creating a hazard to the user and to others.
Sand anchors are known in the art. A prior art plate-type sand anchor may consist of plates, boards or logs buried in the sand and to which a guy line is attached. The plate-type sand anchor may support a tube, such as a tube to receive the end of an umbrella pole. The plate, boards or log must be buried in a hole that is large enough to receive the plate, board or log and deep enough so that the weight of sand on the top of the plate, board or log will adequately apply tension to the guy line or will adequately support the tube. The user must manually dig and fill the hole, which may not be possible for persons having limited strength or endurance.
A tapered thread-type sand anchor includes a tapered shaft having a threaded portion. The user turns the shaft to turn the threaded portion of the tapered thread-type sand anchor, engaging the threads with the sand to pull the sand anchor into the sand. Turning a tapered thread-type sand anchor can require considerable strength and work, placing use of such anchors out-of-reach by persons having limited strength or limited endurance. Rather than turning the shaft, many users may dig a hole in the sand and manually bury the threaded portion of the tapered thread-type sand anchor.
An auger-type sand anchor provides a propeller shape on the end of a tubular shaft. As for the tapered thread-type sand anchor, the user turns the tubular shaft and the propeller shape pulls the auger-type sand anchor into the sand. As for the tapered thread-type anchor, turning a auger-type sand anchor can require considerable strength and work, placing use of such anchors out-of-reach by persons having limited strength or limited endurance. Many users may dig a hole and manually bury auger-type sand anchors rather than attempt to install the anchor by turning the shaft.
An angled tube-type of sand anchor provides a thick-walled cylindrical plastic tube that is driven into the sand. The bottom end of the tube slopes from one side of the tube to the other, so that one side of the tube extends further in the downward direction than the other and providing a relatively sharp point on one side of the tube. In use, the sharp point is driven into the sand using a hammer. During installation, the hollow tube becomes plugged with sand, forming an asymmetrical wedge that forces the sand anchor laterally in response to hammer blows, reducing the contact of the angled tube with the sand and reducing its resistance to pull-out and pull-over. Removing sand packed into the end of the tube also can be a challenge and may require multiple hammer blows.
The prior art does not teach the sand anchor of the Invention.
In overview, the impact sand anchor of the Invention features a plurality of cantilever beams that define an interior volume between the cantilever beams. When the impact sand anchor is driven into the sand, sand packs into the interior volume and forces the cantilever beams to pivot radially from a first position to a second position to engage the sand, securing the impact sand anchor.
The impact sand anchor of the Invention has an anchor top end, an anchor bottom end and an anchor longitudinal axis extending between the top and bottom ends. The bottom end of the impact sand anchor is defined by the plurality of elongated cantilever beams. Each cantilever beam has a cantilever top end and a cantilever bottom end. The cantilever top end of each cantilever beam is defined by a pivot location and each of the pivot locations is attached to each of the other pivot locations. The cantilever bottom end of each cantilever beam can elastically rotate about the pivot location between a first position and a second position. In the first position, corresponding to when the impact sand anchor is not in engagement with sand, the cantilever beams are generally parallel. In the second position, corresponding to when the impact sand anchor is anchored to the sand, each of the bottom cantilever ends is displaced outward radially with respect to the longitudinal axis of the impact sand anchor. In the second position, the cantilever beams are less parallel than when the cantilever beams are in the first position.
The plurality of cantilever beams in combination define an interior volume disposed generally along the anchor longitudinal axis proximal to the anchor bottom end. When the anchor bottom end is driven into the sand, sand is packed into the interior volume and exerts force on the interior side of the cantilever beams. The force exerted by the sand causes each cantilever beam to pivot about the pivot locations to the cantilever second position. The spreading of the cantilever beams to the second position applies force to the sand adjacent to the outer side of the cantilever beams, wedging the cantilever beam in place in the sand.
The allowable radial deflection of the cantilever beams in moving from the first to the second position is limited. Plastic deformation of the cantilever beams resulting from excess deformation at the pivot locations could result in failure of the beams. To prevent excess deformation, a limiter in the form of a ring may be attached, as by welding, to the outer side of one of the cantilever beams and may circle the outer sides of the remaining cantilever beams. The ring is sized to allow the cantilever beams to move between the first and second positions, but to prevent movement of the cantilever beams beyond the second position. Alternatively the cantilever beams may be attached one to the other by a flexible cable on either the inner side or the outer side of the cantilever beams that allows the cantilever beams to move between the first and second positions, but that does not allow over-extension and hence plastic deformation of the pivot locations.
The ring, or, alternatively, the flexible cable, may serve to act as a guide to limit the insertion depth to which the cantilever beams may be driven into the sand. The ring may encircle the cantilever beams at a distance from the bottom end of the sand anchor corresponding to the optimal insertions depth and may contact the sand when the optimal insertion depth is reached, providing a visual cue to the user. In addition, the effort required to drive the sand anchor into the sand beyond the depth of the ring is increased due to the resistance to motion of the ring through the sand, providing an effort cue to the user. The flexible cable, disposed on either the inner side or the outer side of the cantilever beams, may provide the same cues to the user.
The cantilever beams may be of any suitable shape and composed of any suitable material. A shape that has proven suitable in practice is to create the cantilever beams so that the cantilever beams are arcuate in cross section normal to the longitudinal axis of the impact sand anchor. The arcuate shape stiffens the cantilever beams against flexion along their length and allows a smaller cross sectional area than would be the case if the cantilever beams did not have a cross section promoting stiffness in flexion.
Steel has proven to be a suitable material from which to form the cantilever beams. In practice, forming the cantilever beams and the anchor body by cutting a single steel tube has proven successful. Two or more cantilever beams may be created by cutting two or more slots in the steel tube from the bottom end of the steel tube. The curve of the walls of the steel tube define the arcuate cross section of the cantilever beams. The interior of the steel tube inside the cantilever beams thus created defines the inner sides of the cantilever beams and the interior volume of the impact sand anchor, into which sand is packed when the anchor is driven into the sand.
The ends of the slots distal to the bottom end of the steel tube may be manipulated to define the pivot locations, as by terminating each slot with a circular or oblong opening, or with a hole of any suitable shape. The pivot locations effectively are flat springs urging the cantilever beams to the first position. The circular or oblong openings are selected to adjust the spring rate of the flat springs. The use of smoothly curved openings, such as circular or oblong openings, reduces stress risers in the steel tube in the vicinity of the pivot location, extending the life of the impact sand anchor.
The impact sand anchor may include a cylindrical hammer to drive the impact sand anchor into the sand. Where the impact sand anchor is integral with a beach umbrella, the cylindrical hammer may slide on the umbrella shaft. The bottom end of the travel of the cylindrical hammer is defined by a lower stop, which may be the steel tube that defines the cantilever beams. The top end of the travel of the cylindrical hammer also may be defined by an upper stop. The upper stop may be any mechanism to limit the travel of the cylindrical hammer, such as a screw or pin penetrating the shaft on which the cylindrical hammer travels. Alternatively, the cylindrical hammer may be attached to the steel tube by a cable or cord, the cable or cord being selected to have a length adequate to allow the user to use the hammer to strike the lower stop but not long enough to allow the cylindrical hammer to escape the shaft on which it can move.
The cylindrical hammer may include a guard to prevent finger or hand pinches between the cylindrical hammer and the lower stop. The guard comprises a resilient member that encloses the bottom end of the cylindrical hammer. The guard extends beyond the cylindrical hammer in close proximity to the lower stop. If the user inadvertently places the user's hand in the vicinity of the lower stop where the user's finger or hand can be pinched by the cylindrical hammer, the resilient member will push the user's hand out of the way, avoiding injury.
The portion of the resilient guard that may strike the hand of the user may be in the shape of a torroid having a generally triangular cross section or the like so that when the resilient guard strikes the user's hand, a small cross-section of the resilient material first strikes the user's hand, followed by increasing cross-sectional areas of the resilient material. The cylindrical hammer is thus progressively decelerated (or the hand is progressively accelerated out of the way) without a sudden impact of all of the momentum of the cylindrical hammer on the hand of the user.
The resilient member also can serve as a hand grip for a person using the hammer to drive the impact sand anchor into the sand. If the hand grip allows the user to maintain his or her grip of the cylindrical hammer at the end of a stroke, the momentum of the user's moving arm is transmitted through the grip to the hammer, providing more force to drive the impact sand anchor into the sand. A resilient hand grip that allows the user to continue gripping the hammer at the end of the stroke allows use of a smaller and lighter hammer than would otherwise be the case.
An integrated guard and grip in the shape of a sphere; namely, a rubber ball, has proved suitable in practice. The sphere defines a cylindrical hole penetrating the sphere and sized to accommodate the cylindrical hammer and the lower stop. The sphere is bonded to the cylindrical hammer and extends beyond the bottom end of the cylindrical hammer.
The impact of the cylindrical hammer on the lower stop will make noise, even though that noise is suppressed somewhat by the resilient guard overlapping the bottom end of the cylindrical hammer and the lower stop. The noise may be further attenuated by a seal. The seal may be mounted to the anchor body immediately below the lower stop. As the cylindrical hammer approaches the lower stop and just before impact, the inside of the portion of the guard that overlaps the cylindrical hammer comes in contact with the seal, forming a barrier to the air transmission of sound from impact between the cylindrical hammer and the lower stop.
Because of the upwardly-sloping inner sides of the cantilever beams in the second position, removal of the sand packed into the body of the impact sand anchor is remarkably easy—a few tap of the cylindrical hammer on the body dislodges the sand. The impact sand anchor provides an auditory cue that the sand is removed—the pitch of the sound of the impact of the cylindrical hammer changes, signaling that the sand is no longer in place.
The impact sand anchor may be stand-alone and may be installed independently of an object to be supported by the impact sand anchor. In such event, the impact sand anchor of the Invention will be configured to support the object, as by providing a tube attached to the cantilever beams and sized to accept the shaft of a beach umbrella or other object, such as a post to support a net for a sporting contest. Any use to which a beach anchor may be put is contemplated by the invention.
The impact sand anchor may be integral to a beach umbrella, with the shaft of the beach umbrella either permanently or releasably attached to the cantilever beams and cylindrical hammer. If the beach umbrella is attached by a pin connection to the impact sand anchor of the Invention, the pin will be trapped by a slot that extends parallel to the anchor longitudinal axis so that the impact sand anchor may be accelerated downward independently of the beach umbrella (by striking the lower stop with the cylindrical hammer) without also accelerating the mass of the beach umbrella. The use of the slot allowing independent downward acceleration of the impact sand anchor allows the impact sand anchor to be installed to sand while also attached to the beach umbrella.
The impact sand anchor may be included in a kit comprising a beach umbrella and a impact sand anchor, where the beach umbrella is attachable to the impact sand anchor.
The impact sand anchor may be utilized in a method of supporting a beach umbrella.
The Invention is a sand anchor, a umbrella integrated with a sand anchor, a kit including the sand anchor and a beach umbrella, and a method of supporting a beach umbrella using the sand anchor.
A plurality of cantilever beams 12 may be defined by the body 4. The drawings illustrate two cantilever beams 12, which has proven suitable in practice; however, any number of cantilever beams 12 greater than one is contemplated by the Invention. Each of the cantilever beams 12 has a cantilever top end 14, a cantilever bottom end 16 and an elongated dimension 18 between the cantilever top end 14 and the cantilever bottom end 16. The plurality of cantilever beams 12 each has a pivot location 20 and can move between a first position (
The first position, as illustrated by
The improved strength of the connection of the sand anchor 2 to the sand 26 allows the sand anchor 2 to be driven to an insertion depth 42 that is shallower than otherwise would be the case and to nonetheless adequately anchor the beach umbrella 84 or other object to the sand 26. An insertion depth 42 of nine inches has proven suitable in practice.
From
To avoid pinch injury to the hand of the user and as shown by
A hole is defined by the spherical guard 60 to allow the guard 60 to encircle and engage the cylindrical hammer 50 and to clear the lower stop 54. The shape of the bottom end 64 of the guard 60 is defined by the guard 60 and the hole penetrating the guard 60. The shape of the bottom end of the guard 60 may approximate a torroid having a generally triangular cross section. When the bottom end of the guard 64 strikes the hand of a user, a small cross sectional area of the resilient material 62 from which the guard 60 is composed first engages the hand. As the resilient material 62 compresses as a result of the collision, the cross sectional area of the resilient material engaging the hand increases, with the cross-sectional area of the resilient material engaging the hand increasing as the collision progresses. Because the force exerted by the guard 60 on the user's hand is proportional to the cross sectional area of the resilient material acting upon the hand, the force applied to the user's hand by the cylindrical hammer 50 increases progressively until the hand is pushed out of the way of the hammer 50. The user's hand does not experience the impact of the cylindrical hammer 50 on the lower stop 54.
Any other shape of the guard 60 and its bottom end 64 is contemplated by the invention.
From
From
From
As shown by
The slot 92 also assists in installation of the combination of the umbrella 84 and impact sand anchor 2 into the sand 28 when the umbrella 84 and the impact sand anchor 2 are attached. The slot 92 extends below the pin 94 in the downward direction 58 when the shaft 86 and the body 4 are engaged. When the user places the cantilever beams 12 in contact with the sand 28 and operates the cylindrical hammer 12, the pin 94 does not engage the end of the slot 92 and does not impart force from the hammer 50 to the shaft 86 and hence to the remainder of the umbrella 84. The mass of the shaft 86 and canopy 88 of the umbrella 84 therefore does not resist the acceleration imparted to the body 2 by the cylindrical hammer 50. In response to a blow from the cylindrical hammer 50, the impact sand anchor 2 moves in a downward direction 58 below the shaft 86 and umbrella 84. The shaft 86 and umbrella 84 then fall by the force of gravity for a short distance and catch up to the now-stationary impact sand anchor 2. The collision between the falling shaft 86 and umbrella 84 and the stationary impact sand anchor 2 drives the impact sand anchor 2 deeper into the sand 28.
From
From
The Invention is also a method of supporting an object, such as an umbrella 84 using the impact sand anchor 2. In the method of the invention, the first step is to place the cantilever bottom end 16 of the cantilever beams 16 in contact with the sand 28. The second step is to alternately slide the cylindrical hammer 50 up and down the body 4, impacting the cylindrical hammer 50 against the lower stop 54 and driving the cantilever beams 12 into the sand 28. The cantilever beams 12 will move to the second position, as described above, anchoring the impact sand anchor 2 to the sand 28. If the shaft 86 of the umbrella 84 or other object to be supported is in engagement with the body 4, then the installation is complete. If the shaft 86 of the umbrella 84 or other object to be supported is not already in engagement with the body 4, the third and final step is to place the shaft 86 in engagement with the body 4, completing the installation.
The inventors have performed comparison testing of the impact sand anchor 2 of the Invention to other available sand anchors and to a bare pole to determine the strength of the connection of the sand anchors and bare pole to the sand. For each test, the sand anchor or pole was installed in the sand per manufacturer's direction and embedded to the depth indicated below. A force gauge was attached to the sand anchor to be tested. For the pullout test, the force required to pull the sand anchor or pole from the sand 28 along the longitudinal axis of the pole was measured. For the pullover test, the force required to cause the shaft attached to the sand anchor to tilt at an angle of 45 degrees was measured, where the force was applied to a shaft four feet above the surface of the sand 28 and in a direction parallel to the surface of the sand 28. All tests were performed in moist sand below the high tide mark on a beach.
In the following table, the ‘impact sand anchor’ is the impact sand anchor described in this document. The ‘tapered thread anchor’ is generally in the shape of a narrow cone having threads on the cone. The ‘auger-type anchor’ comprises a tube having a propeller-shaped auger at its bottom end. The results are as follows:
Pullout Force (Force Along the Longitudinal Axis)
From the foregoing, the tapered threaded anchor performed well against pullout, but was weak against pullover, weaker than even the bare pole. The bare pole provided very little resistance to pullout, but was better resisting pullover. The impact sand anchor 2 of the Invention and the auger-type sand anchor both performed well under both pullout and pullover loads; however, the impact sand anchor 2 of the Invention was much faster and easier to install than the auger-type sand anchor.
During the testing the tapered thread anchor and the auger-type anchor both required substantial upper-body strength to install, and required an average of 40 seconds to embed the sand anchors to the prescribed depth. The impact sand anchor 2 of the invention required an average of 15 seconds to install, with much less upper body strength required.
This utility patent application for an impact sand anchor is entitled to priority from provisional application 61/894,777 by Edward Wojtowicz filed Oct. 23, 2013. Application 61/894,777 is incorporated by reference as if set forth in full herein.
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2227021 | Sep 1999 | CA |
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2132659 | Jul 1984 | GB |
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Number | Date | Country | |
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61894777 | Oct 2013 | US |