WO2000066395A1

WO2000066395A1 - Tie down strap

Info

Publication number: WO2000066395A1
Application number: PCT/US2000/012263
Authority: WO
Inventors: Eric D. Hyp
Original assignee: Southco, Inc.
Priority date: 1999-05-05
Filing date: 2000-05-04
Publication date: 2000-11-09
Also published as: WO2000066395A9; AU4702800A

Abstract

An elastic tie down strap (10) for securing a tonneau cover to a truck bed has a handle (50) and integrally formed loop (30). When stretched the strap deforms in three stages, each stage requiring a force greater than the previous stage. One segment of the loop (30) initially has a smaller modulus than the other. As the strap (10) is stretched and the geometry of the loop (30) changes, the first segment provides a greater modulus than the second.

Description

TIE DOWN STRAP

BACKGROUND OF THE INVENTION

1. Field of the Invention The present invention relates to latches and in particular to latches for securing covers such as tarps or tonneau covers for pick-up truck beds.

2. Brief Description of the Prior Art

There are a variety of systems for covering the open bed of a pick-up truck or a portion, or all, of the open passenger compartment of a convertible automobile. Such covers are conventionally known as "tonneau" covers, and can be fabricated from rigid materials such as fiberglass sheet, or flexible materials such as fabric. Tonneau covers can decrease wind resistance, thereby increasing gas mileage. Additionally, tonneau covers can conceal cargo and protect cargo from the environment. An example of latches incorporating a lever to stretch a rubber latch body is provided by the "37" series of latches marketed by Southco, Inc., Concordville, PA.

Flexible tonneau covers are disclosed, for example, in U.S. Patent 5,860,691 that employs a set of channels and ridges to bias a fabric cover. U.S. Patent 4,991 ,640 discloses a fastening system for securing a flexible cover to a truck body that employs a pair of rear cover locking devices. U.S. Patent 5,772,273 discloses a spring clip for retaining snap fasteners on a tonneau cover rail.

When a flexible material is used, such as vinyl sheet or fabric such as a vinyl-coated polyester fabric, it is desirable to hold the flexible material in place with a bias or tension. Springs or elastic straps can be used. To stretch the flexible cover flat, a significant amount of spring force must be applied. However, it is difficult to exert enough force to attach elastic straps that are sufficiently forceful to securely hold the tonneau cover in place. There is a need for a latching device to permit tonneau covers made from flexible materials to be easily yet securely attached to pick-up truck beds. SUMMARY OF THE INVENTION

The present invention provides a tie down strap for securing a tonneau cover to a truck bed. The truck bed and the tonneau cover each preferably include anchor points for the tie down strap. The tie down strap is adapted to deform in three stages, each stage requiring a force greater than the previous stage. The tie down strap comprises a handle and a generally "O"-shaped loop formed from an elastomeric material, preferably integrally formed. The strap further includes a means for securing the strap to a first anchor point and a means for securing the strap to a second anchor point. The axis of deformation of the strap lies along the line defined by the means for securing the strap to the anchor points.

The loop includes two segments, with the first segment preferably having a smaller elastic modulus than the second segment during the first stage of deformation. During the second stage of deformation, the second segment preferably has a smaller elastic modulus than the first segment. Finally, the first segment has a greater elastic modulus than the second segment during the third stage. The changing elastic modulus relates to the way in which the geometry of the loop changes as the strap is stretched. Preferably, the geometry of the loop changes as the strap is deformed such that a generally axial load is applied to the first segment during the third stage.

Preferably, the loop comprises a first side section, a second side section generally parallel to the first side section, and a pair of generally "U"-shaped end sections connecting the first and the second side sections. The first segment of the loop comprises the first side section and the two end sections, and the second segment of the loop comprises the second side section. Preferably, both the first and second segments have generally uniform, but differing, cross- sectional areas. The cross-sectional area of the second segment is preferably greater than the cross-sectional area of the first segment. The changing elastic modulus is accomplished by the combination of the differing cross-sectional areas, the greater area providing a high modulus, and the geometry of the loop. Preferably, the loop is bilaterally symmetric, and when the tie down strap is relaxed, the side sections of the loop are spaced, generally parallel, and oriented perpendicular to the axis of deformation of the strap. Preferably, the loop is integrally formed with the handle, and the handle preferably extends from the second side section of the loop, along the deformation axis of the strap.

The means for securing the strap to a first anchor point preferably comprises a mounting ring formed at an end of the handle, and the means for securing the strap to a second anchor point preferably comprises a knob formed on the first side section of the ring, with the knob having an aperture formed therein for receiving a pin.

The loop provides three distinct stages of force during use of the strap. In the first stage, the operator grasps the handle and pulls back. During this first stage, the first segment of the loop deforms and the loop changes shape. Because of the geometry of the loop, the deformation during the first stage requires only minimal force. In the second stage, the operator continues to pull back on the handle. During this second stage, the second segment of the loop deforms. This deformation requires more force, as the second segment has a greater elastic modulus than the first segment. This second stage of deformation provides some "pre-load" in the strap that is intended to help compress the gasketing around the truck bed cover and will help keep the strap in place when the vehicle is moving. In the third stage, the operator continues to pull back on the handle and then slips the mounting ring over the mounting peg or hook on the truck bed and releases the handle. In the third stage, the side sections of the loop are generally parallel to one another, and the force required to stretch the loop is much greater than required in the second stage because the side sections are now in an axial load condition.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of the tie down strap. Figure 2 is a front elevational view of the tie down strap of Figure 1. Figure 3 is a rear elevational view of a tie down strap of Figure 1. Figure 4 is a top plan view of the tie down strap of Figure 1.

Figure 5 is a side elevational view of the tie down strap of Figure 1. Figure 6 is a top plan view of the tie down strap of Figure 1 shown in a relaxed position.

Figure 7 is top plan view of the tie down strap of Figure 1 shown in a partially extended or stretched position. Figure 8 is top plan view of the tie down strap of Figure 1 shown in a more fully extended or stretched position.

DETAILED DISCLOSURE The present invention provides an elastic latch or tie down strap 10 with three stages of latching force. First, a minimal effort makes it easy to position the free end of the strap near the latch point. Secondly, additional force must be exerted to build up some pre-load in the strap. This will help compress the gasketing around the bed cover and help keep the strap in place during vehicle motion. Third, still more force must be exerted to fully stretch the strap and prevent further strip elongation. This will prevent access to the truck bed when the cover is in place.

The present invention includes a single, integrally formed principal component, the strap body 20, formed by molding or another technique from an elastic material such as natural or synthetic rubber. Additional components can also be included for attaching the strap body 20 to various types of mounts for various uses.

Referring now to the drawings in detail, wherein like reference numerals indicate like elements throughout the several views, there is shown in Fig. 1 a perspective view of a tie down strap or latch 10 of the present invention. The tie down strap 10 comprises a body 20 having an integral, elongated generally "O"- shaped loop section 30 and an integral, generally cylindrical handle section 50.

The tie down strap 10 is bilaterally symmetric and is preferably made from an elastic material such as a natural or synthetic elastomer, for example by molding followed by vulcanization.

As best seen in the side elevational view of Figure 5, on one side of the loop section 30 at the midpoint of the loop section, a knob 32 is formed having an aperture 34 extending therethrough for receiving a pin (not shown) for permanently attaching the strap 10 to an object to be restrained, such as a truck bed cover (not shown). Other mounting arrangements can be substituted for the knob 32 and pin depending on the application.

The loop section 30 includes four sections, a pair of spaced, generally parallel, generally cylindrical side sections 36, 38, connected by a pair of integrally formed generally "U"-shaped end sections 40, 42 Each of the first side section 36 and two end sections 40, 42 have the same circumference, these three sections 36, 40, 42 collectively defining a first segment 44 of the loop section 30. The second side section or second segment 38 has a circumference greater than the circumference of the first segment 44 of the loop section 30.

The generally cylindrical handle section 50 extends from the midpoint of the second segment 38 and is coplanar with the loop section 30. The handle section 50 is adapted to be securely grasped by an operator, and to decrease slippage during use. At one end (the "free" end) of the handle section 50 a mounting ring 60 is formed having a mounting aperture 62 formed therein for attaching the strap 10 to a hook or peg (not shown) mounted on the truck to secure the strap 10.

As shown in Figures 6-9, the purpose of the loop section 30 is to provide three distinct stages of force during use of the strap 10. In the first stage, the operator grasps the handle section 50 and pulls back in the direction of arrow 70 of Figure 6. During this first stage, the thin first segment 44 of the loop section 30 deforms and the loop section 30 changes shape until the loop section 30 appears as shown in Figure 7. Because of the geometry of the loop section 30, the deformation of the loop section 30 during the first stage requires only minimal force. This makes it easy to position the free end and mounting ring 60 near the hook or latch point.

In the second stage, the operator continues to pull back on the handle section 50. During this second stage, the second, thicker segment 38 deforms. This deformation requires more force, simply because this second segment 38 is thicker than the first segment 44. This second stage of deformation builds some "pre-load" into the strap 10 that will help compress the gasketing around the bed cover (not shown) and will help keep the strap 10 in place when the vehicle is moving. The terminus of this second stage is illustrated by Figure 9.

In the third stage, the operator continues to pull back on the handle section 50 and then slips the mounting ring 60 over the mounting peg or hook on the truck bed and releases the handle 50. In the third stage, the side sections 32, 34 of the loop 30 are generally parallel to one another, and the force required to stretch the loop 30 is much greater than required in the second stage because the side sections 32, 34 are now in an axial load condition. The appropriate cross-sectional dimensions and configuration of the loop section segments 38, 44 can be determined by experimentation, and will depend on the specific use of the strap 10.

Claims

CLAIMSI claim:

1. A tie down strap for securing a tonneau cover to a truck bed, the truck bed and the tonneau cover including anchor points for the tie down strap, the tie down strap comprising: a means for securing the strap to a first anchor point; a handle; a generally "O"-shaped loop formed from an elastomeric material, the loop having a first segment and a second segment; and a means for securing the strap to a second anchor point, the strap having an axis of deformation along the line defined by the means for securing the strap to the anchor points; the tie down strap being adapted to deform in three stages, each stage requiring a force greater than the previous stage.

2. A tie down strap according to claim 1 wherein the first segment has a smaller elastic modulus than the second segment during the first stage.

3. A tie down strap according to claim 2 wherein the first segment has a greater elastic modulus than the second segment during the third stage.

4. A tie down strap according to claim 1 wherein the geometry of the loop changes as the strap is deformed such that a generally axial load is applied to the first segment during the third stage.

5. A tie down strap according to claim 1 wherein the loop comprises a first side section, a second side section generally parallel to the first side section, and a pair of generally "U"-shaped end sections connecting the first and the second side sections, the first segment of the loop comprising the first side section and the two end sections, the second segment of the loop comprising the second side section.

6. A tie down strap according to claim 5 wherein the first segment has a generally uniform cross-sectional area, and the second segment has a generally uniform cross-sectional area, the cross-sectional area of the second segment being greater than the cross-sectional area of the first segment.

7. A tie down strap according to claim 5, wherein the side sections are spaced, generally parallel, and oriented perpendicular to the axis of deformation.

8. A tie down strap according to claim 1 wherein the strap is bilaterally symmetric.

9. A tie down strap according to claim 5 wherein the loop is bilaterally symmetric.

10. A tie down strap according to claim 5 wherein the handle extends from the second side section of the loop.

11. A tie down strap according to claim 1 wherein the means for securing the strap to a first anchor point comprises a mounting ring formed at an end of the handle.

12. A tie down strap according to claim 1 wherein the means for securing the strap to a second anchor point comprises a knob formed on the first side section of the ring, the knob having an aperture formed therein for receiving a pin.

13. A tie down strap according to claim 1 wherein the loop is integrally formed with the handle.