BACKGROUND OF THE INVENTION
The invention relates to a latch assembly or buckle, used for example with a cargo belt or strap for securing a load. The cargo belt is used to hold a top cap and pallet contents, such as totes, boxes, or dunnage, on a pallet. With a typical pallet, load, and plastic top cap, the retractor for the cargo belt is installed on the pallet and the buckle (latch) is commonly installed or mounted on the top cap.
Many latches employ a press-sticker style release buckle, or an aircraft-lever style release buckle, in conjunction with a cargo belt or strap to secure loads. These types of latches may become extremely difficult or impossible to disconnect or release under certain circumstances, such as when the buckle and/or tongue has become damaged during handling of the secured pallet, or when the cargo strap is subjected to heavy tension or loads, which may arise because of shifting of the cargo during transportation of the pallet. As a result of the difficulty in disconnecting these latches, the cargo belt may have to be cut to release and access the cargo load, resulting in a need to replace the belt for future use.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view of a latch assembly in use with a pallet, top cap, and load;
FIG. 2 is a perspective view of the latch assembly of FIG. 1, showing a tongue engaged in a buckle;
FIG. 3 is an exploded perspective view of the buckle;
FIG. 4 is a perspective view of a portion of the buckle;
FIG. 5 is a perspective view of the tongue; and
FIGS. 6 through 13 are a series of schematic side views, partially in section, showing various steps in the engagement and disengagement of the latch assembly.
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
FIG. 1 illustrates schematically a latch assembly 10, used for example with a cargo belt or strap 12 for securing a load 14. The cargo belt 12 is used to hold a top cap 16 and the load or pallet contents 14, such as totes, boxes, or dunnage, on a pallet 18. The latch assembly 10 may be used in other applications or environments.
The latch assembly 10 (FIG. 2) includes a buckle 20 and a tongue 22. The tongue 22 is engageable with the buckle 20 in a secure locking arrangement that can be easily released as described below.
The buckle 20 (FIGS. 2-4) includes a housing or base 30. The base 30 may be stamped and formed from one piece of metal as shown. The base 30 includes a bottom wall 32, and two upstanding, parallel side walls 34 and 36. A pair of top flanges 38 extend inward toward each other from the side walls 34 and 36. The bottom wall 32, side walls 34 and 36, and top flanges 38 delineate a slot 40 for receiving the tongue 22, at the front end 42 of the buckle 20.
Extending between the side walls 34 and 36 is a first pivot pin in the form of a rivet 50. The first pivot pin 50 defines a first pivot axis 52 of the buckle 20. Extending between the side walls 34 and 36 is a second pivot pin in the form of a rivet 54. The second pivot pin 54 defines a second pivot axis 56 of the buckle 20.
The base 30 has a projecting tab 57 of at the back end 58 of the base, with an opening 59 for securing the buckle 20. The opening 59 is adapted to receive a fastener (now shown) for securing the buckle 20 to, for example, a top cap or a pallet. The buckle 20 may include alternative means for securing the buckle.
The buckle 20 includes a locking pawl 60. The locking pawl 60 has a generally L-shaped configuration including a first leg 62 and a second leg 64. The first pivot pin 50 extends through the locking pawl 60 at a location between the first and second legs 62 and 64. The locking pawl 60 is supported on the first pivot pin 50 for pivoting movement about the first pivot axis 52 relative to the base 30. A pair of bushings 66 on the pivot pin 50 serve to center the locking pawl 60 laterally in the buckle 20.
A return spring or locking pawl spring 68 on the pivot pin 50 acts between the locking pawl 60 and the base 30. The pawl spring 68 biases the locking pawl 60 for pivoting movement in a clockwise direction as viewed in FIGS. 6-13. Thus, under the influence of the pawl spring 68, the locking pawl 60 has a first or disengaged position as shown in FIG. 6. The locking pawl 60 is movable, under the influence of force applied by the tongue 22 as described below, from the disengaged condition to an engaged condition as shown in FIG. 11, and to various other positions also.
The buckle 20 (FIGS. 2-4) includes a release lever 70. The release lever 70 has a cutout 72 between a base portion 74 and a handle portion 76 of the release lever. An edge surface 78 on the handle portion 76 of the release lever 70 partially defines the cutout 72 in the release lever. The cutout 72 is a space in the release lever 70 into which a portion of the locking pawl 60 can enter.
The release lever 70 is supported on the second pivot pin 54 for pivoting movement about the second pivot axis 56 relative to the base 30. A pair of springs 80 on the second pivot pin 54 serve to center the release lever 70 laterally in the buckle 20. The release lever springs 80 act between the release lever 70 and the base 30. The release lever springs 80 bias the release lever 70 for pivoting movement in a clockwise direction as viewed in FIGS. 6-13. Thus, under the influence of the release lever springs 80, the release lever 70 has a closed, or rest, position as shown in FIG. 6. The release lever 70 is movable, under the influence of force applied by a user or by the locking pawl 60, as described below, out of the closed condition.
The tongue 22 (FIG. 5) in the illustrated embodiment is made as one piece from a suitable material, such as steel. The tongue 22 has a generally planar configuration including two longitudinally extending side bars 82 and three cross bars 84, 86 and 88 that extend laterally between and interconnect the side bars.
A first opening in the form of a cutout 90 is defined between the first cross bar 84 and the second cross bar 86. The cutout 90 is a space in the tongue 22 into which a portion of a locking pawl can enter. A second opening 92 in the form of a slot is defined between the second cross bar 86 and the third cross bar 88. The slot 92 is adapted to receive a loop of the strap 12, thereby to connect the strap with the tongue 22.
The first cross bar 84 has a leading edge 94 that forms a leading edge of the tongue 22 (leading in the direction of movement of the tongue to engage the buckle, i.e., to the left as viewed in FIGS. 6-7). The second cross bar 86 has a leading edge 96 that partially defines the cutout 90 in the tongue 22.
The buckle 20 has a free condition as shown in FIG. 6. In this condition, the locking pawl 60 is biased in a first direction by the pawl spring 68 to a position in which the first leg 62 of the locking pawl extends upward (in a direction away from the bottom wall 32 of the base 30). The first leg 62 of the locking pawl 60 extends at least partially into the slot 40 in the base 30, to obstruct the slot. The release lever 70 is biased in a first direction by the release lever springs 80 to a position overlying the top flanges 38 of the base 30. The first leg 62 of the locking pawl 60 may, as shown in FIG. 6, extend at least partially into the opening 72 in the release lever 70.
To engage the tongue 22 with the buckle 20, the tongue is inserted into the slot 40 at the front end 42 of the buckle, as shown schematically in the sequence of drawings labeled FIGS. 6-11. As this movement of the tongue 22 occurs, the leading edge 94 of the tongue engages the first leg 62 of the locking pawl 60, which obstructs the slot 40. The force transmitted by the moving tongue 22 causes the locking pawl 60 to pivot about the first pivot axis 52, in a counter-clockwise or second direction as viewed in FIGS. 6-11, against the biasing force of the pawl spring 68.
As the linear movement of the tongue 22 and the pivoting movement of the locking pawl 60 continue, the second leg 64 of the locking pawl pivots upward into the buckle slot 40 (FIG. 7). At this time, the tongue 22 has moved into the buckle slot 40 far enough that the cutout 90 in the tongue is near the first pivot axis 52. Therefore, as the second leg 64 of the locking pawl 60 pivots upward, the second leg 64 moves into the cutout 90 of the tongue 22, as shown in FIGS. 7-9.
As the tongue 22 continues to insert, the leading edge 94 of the tongue continues to engage the first leg 62 of the locking pawl 60 and the locking pawl continues to pivot, through the positions shown in FIGS. 7 and 8 to the position shown in FIG. 9. In this position, the second leg 64 of the locking pawl 60 moves upward through the cutout in the tongue 22 and into engagement with the lower side surface of the handle portion 76 of the release lever 70. The continued pivoting movement of the locking pawl 60 causes the release lever 70 to be lifted (pivoted) a small amount, as shown in FIG. 9 and 10, moving in a second direction, until the second leg 64 of the locking pawl moves into the opening 72 in the release lever. The release lever 70 then snaps back into its original position, moving in the first direction under the influence of the release lever springs 80.
When the release lever 70 is thus returned to its closed position (FIG. 10), the biasing force of the pawl spring 68 causes the second leg 64 of the locking pawl 60 to pivot (in a clockwise direction as viewed in FIGS. 10 and 11) so as to engage the edge surface 78 on the handle portion 76 of the release lever. This engagement blocks further pivoting movement of the locking pawl 60 in the clockwise direction.
Thus, when the tongue 22 is fully engaged or fully inserted in the buckle 20, the second leg 64 of the locking pawl 60 extends through the cutout 90 of the tongue 22 and is also located in the cutout 72 of the release lever 70. Any force on the tongue 22, tending to pull the tongue out of the buckle 20 (FIG. 12), is transmitted to the locking pawl 60 and thus causes the locking pawl to engage the edge surface 78 on the release lever 70. The engagement of the locking pawl 60 with the release lever 70 blocks further rotation of the locking pawl.
In this position of the parts, the second leg 64 of the locking pawl 60 extends through the cutout 90 in the tongue 22. As a result, the tongue 22 can move in the release direction out of the buckle 20 (to the right as viewed in FIGS. 12 and 13) only until the first cross bar 84 of the tongue engages the second leg 64 of the locking pawl 60. This engagement blocks further movement of the tongue 22 in the release direction, and thus blocks removal of the tongue from the buckle 20. The latch assembly 10 is thus fully engaged.
To open the buckle 20, the release lever 70 is lifted (FIG. 13) and pivoted in the second direction about the second pivot axis 56. When the release lever 70 is raised sufficiently, the handle portion 76 of the release lever moves out of engagement with the second leg 64 of the locking pawl 60. The second leg 64 of the locking pawl 60 is no longer located in the cutout 72 of the release lever 70. The pawl spring 68 urges the locking pawl 60 to pivot clockwise, toward its initial position, thereby moving the second leg 64 of the locking pawl out of the cutout 90 in the tongue 22. The locking pawl 60 no longer blocks movement of the tongue 22 out of the buckle 20. The tongue 22 is free to pull out of the buckle 20 under tensile force applied to the tongue by the strap 12.
As the locking pawl 60 returns to its initial position, the force of the pawl spring 68, transmitted through the locking pawl, may assist the tongue 22 in disengaging from the buckle 20. Even if this does not occur, however, the free rotation of the locking pawl 60 about the first pivot axis 52 still permits the tongue 22 to disengage from the buckle 20 with little or no resistance.
In this manner, the latch assembly 10 is released by simply lifting the release lever 70, and tensile force on the tongue 22 will pull the tongue out from the buckle 20. Even if an extreme tension or load is applied to the strap 12, causing the tongue 22 to pull the locking pawl 60 tightly against the handle portion 76 of the release lever 70, the release lever can still be lifted away from the locking pawl because of its relatively long lever arm and the fact that the force of the locking pawl is acting on the release lever in a direction transverse to the lifting direction of the release lever. Thus, the latch assembly 10 provides relatively “fail safe” un-latching or disengagement of the strap 12, even where the tongue 22 may be damaged or where an extreme tension or load is applied to the strap. This avoids the undesirable consequence of having to cut the strap 12 to release the load 14.
The latch assembly 10 may optionally be provided with a tamper detection device 100. The tamper detection device 100 may be a mechanism that prevents or resists, or shows, movement of the release lever 70 out of the release position. In one embodiment, as shown in FIG. 2, two small holes 102 may be provided, one on either side of the top of the release lever. The holes allow for a tamper detection member 104 to be placed through one or both of the holes 102 and through the slot 92 of the tongue 22. The tamper detection member 104 may be, for example, a wire of some type than can have its two ends connected to form a ring. The tamper detection member 104 need not lock the release lever in place, but may merely provide a visual indication as to whether the load 14 has been tampered with or opened up. This method of tamper detection may help an end user save on the cost of lost or stolen materials. The tamper detection device 100 may also help to prevent the latch assembly 10 from being inadvertently released by preventing opening movement of the release lever 70.
Patent Application
20070130735
