Patent Abstract:
An apparatus for automatically latching and unlatching the lid of a container is disclosed which includes a weight pivotally mounted on the side of the container for movement between first and second positions. The weight is positively connected to a latch by a connecting rod, and as the weight pivots between first and second positions, it move the latch between latching and unlatching positions. Tipping the container causes the weight to shift thus the container is unlatched only when it is being dumped. A method for operating the latch is also disclosed.

Full Description:
FIELD OF THE INVENTION  
         [0001]    The present invention is directed to an automatic container latch and method of operating same, and more specifically, toward a gravity-operated container latch that shifts from a latched to an unlatched position when a container is pivoted from a rest orientation to a dumping orientation.  
         BACKGROUND OF THE INVENTION  
         [0002]    Facilities that produce substantial amounts of waste often dispose it in large trash receptacles that are emptied periodically by a trash truck. Generally, the receptacles are formed from steel or a similar material and are too heavy to lift manually, especially when full. A trash truck having a special lift is thus normally used to raise and empty these containers. To lift a container, the truck parks so that fingers on a lift arm on the truck can be inserted into special openings on the trash receptacle. The lift arm is then raised in an arc toward an opening in the top or side of the truck and tipped toward the opening until all trash in the receptacle falls out. Such trash receptacles often have lids hingedly connected to the their main bodies, and the lids pivot open as the receptacle is tipped. After the receptacle has been emptied, the lift arm returns it to an upright position and lowers it to the ground.  
           [0003]    Certain trash receptacles are used with trash compactors that have a ram for forcing trash into the receptacle to reduce its volume and increase its density. These rams often push trash into a receptacle from one side, and it is thus necessary to hold the receptacle lid securely in place or the compacted trash will be forced upward by the ram and rise up and out of the receptacle. Even small gaps between the receptacle and its lid may allow unacceptable amounts of trash to escape, especially when the trash has a significant liquid component. These receptacles therefore generally include a latching mechanism that holds the receptacle lid securely closed and allows little or no gap between the container body and the lid even when trash therein is being compressed.  
           [0004]    When such containers are to be emptied by a trash truck, a truck driver or another person must approach the trash container, release the latch, dump the receptacle into the truck and then return to re-latch the container. This latching and unlatching significantly reduces the advantages of using an automatic trash collection truck.  
           [0005]    Automatic latch releases are known from the prior art which may be opened and closed by a radio transmitter, for example. However, such electronic solutions can be expensive to implement and require that the operator of a trash truck carry one or more transmitters for opening any container on his route. Also know from the prior art are containers with latches that are actuated by gravity when the container tips from an upright to a dumping position. Most of these latches, however, are designed either to keep a container lid closed under high wind conditions or to prevent unauthorized persons from gaining access to the trash container and are not suited for use with a compactor receptacle that is subjected to significant internal pressures during use. For example, U.S. Pat. No. 5,094,487 shows a trash receptacle comprising a body and a lid that has a housing mounted on one of the body sidewalls. A hook depends from the lid and extends into the housing when the lid is closed and the container is resting on its bottom. A freely pivotable rod inside the housing includes a projection that engages the hook when the container is horizontal and that pivots away from the hook to release it when the container is tipped. However, the clearances required by this arrangement do not allow the lid to be held completely shut, and thus the lid would open under the application of pressure from within and force trash out of the top thereof. U.S. Pat. No. 4,155,584 shows an automatic lock for a container that includes a pivotable weight which swings though an arc and impacts against a latch to release the latch when the container is inverted. This complex arrangement requires that the weight impact against a release with sufficient force to unhook the latch. If the lid of a receptacle is forced upwardly by pressure from compacted trash inside the container, the unlatching device might not function properly. Furthermore, the swinging arm impacting against a release is likely to lead to wear and may require the device to be replaced or repaired with some frequency.  
           [0006]    There is thus a need for a container latch that automatically unlatches when the container is pivoted from a resting orientation to a dumping orientation and which re-latches when the container is returned to its resting orientation, which latch functions even when the contents of the container are under pressure and which holds the lid of the container securely closed with little or no gap between the lid and the container.  
         SUMMARY OF THE INVENTION  
         [0007]    These problems are overcome by the subject invention which comprises an automatic latching device for a container such as a trash receptacle. The subject invention is particularly useful for securing the lids of trash receptacles, especially trash receptacles that are used in conjunction with a trash compactor that forces trash into the container under pressure; however the invention could be practiced with other types of dumpable receptacles without departing from the scope of this invention. Thus, while the container described herein is generally referred to a trash receptacle, the use of invention is in no way limited to such containers.  
           [0008]    In the preferred embodiment, the invention is a container having a pivotable lid with a projection near its free end. This projection is engaged by a hook pivotally mounted on the sidewall of the container body. When the hook engages the projection, the lid is held firmly against the top of the container body. Furthermore, because the hook is pivotally mounted, it can resist upward pressure on the lid such as may be exerted when the container receives trash under pressure from a compactor. Also attached to the container sidewall is a weight mounted for pivotal movement about an axis located near the edge of the weight which weight assumes a first position when the container is in an upright position and a second position when the container tips toward a dumping position. The weight is connected to the hook by a rigid rod, and when the weight pivots, it moves the rod and the hook to release the hook or reengage it with the projection. As described more fully hereinafter, the arrangement of the rod and the weight increases the effective force applied against the hook to provide for secure, positive latching.  
           [0009]    Also according to the preferred embodiment, the weight is mounted in a bi-stable manner so that once it becomes unbalanced it shifts from the first position to the second position and does not remain in an intermediate position for a significant amount of time. This helps ensure that the latch is positively engaged or disengaged and not left in some intermediate position. In addition, two stops are provided to limit the pivotal movement of the weight. The relationship between the center of gravity of the weight and the weight&#39;s axis of rotation is selected so that once the center of gravity passes over the pivot axis, the weight falls a further distance and impacts against a stop. Thus when the container moves from a rest orientation to a dumping orientation, the weight shifts when the container is tipped at a first angle, and when the container is moved from a dumping orientation to a rest orientation, the weight shifts back when the container is tipped at a second angle. This allows the latch to be latched and unlatched at different points in the travel of the container from a rest orientation to a dumping orientation, depending on the direction that the container is being tipped. Preferably, the lid is kept latched until the container opening is nearly vertical or until the container is inverted to ensure no trash falls from the container before it is properly positioned. However, the lid cannot be re-latched until the lid falls back onto the container body under the force of gravity when the container is relatively horizontal.  
           [0010]    It is therefore a principal object of the present invention to provide a dumpable container having an automatic latch release.  
           [0011]    It is another object of the present invention to provide a gravity-operated latch for a lidded container.  
           [0012]    It is a further object of the present invention to provide a gravity-operated latch for a dumpable container that includes a bi-stably mounted actuating weight.  
           [0013]    It is still another object of the present invention to provide a gravity-operated latch for a dumpable container that includes a weight positively coupled to a fastener to positively shift the fastener between first and second positions as the weight moves.  
           [0014]    It is still a further object of the present invention to provide a method of positively latching and unlatching a container using a gravity-operated actuator.  
           [0015]    It is yet another object of the present invention to provide a method of latching a lid to a container body in a manner that holds the lid securely against the container body using a gravity-operated actuator.  
           [0016]    In furtherance of these objects, a container is provided that comprises a body having an interior, an exterior, a sidewall and a top opening, and a lid having a first end hingedly connected to the body and a second end, the lid being shiftable between a closed position covering the top opening and an open position allowing access to the interior. The lid is secured by a fastener and the fastener is positively shifted between a securing and a releasing position by a gravity-operated actuator that includes a weight mounted on the body exterior for bi-stable movement between a first position and a second position with respect to the sidewall, and a rigid link connecting the weight to the fastener so that the fastener is shifted from the securing position to the releasing position when the weight shifts from the first position to the second position.  
           [0017]    The invention further comprises a container adapted to be moved from a rest orientation to a dump orientation during a dumping operation including a body having an interior and a top opening into the interior and a lid having a first end hingedly connected to the body and shiftable between a closed position covering the top opening and an open position allowing access to the interior. The container assumes a first angular orientation with respect to the ground when it is in a rest orientation and a second angular orientation with, respect to the ground when it is in the dump orientation. The container also includes a fastener for holding the lid in the closed position and substantially preventing movement of the lid when pressure is applied against the lid from the interior and an actuator for positively shifting the fastener between a securing and a releasing position. The actuator includes a weight pivotably mounted on the body for movement to a first position with respect to the sidewall when the container has a first angular orientation with respect to the ground and to a second position with respect to the sidewall when the container has a second angular orientation with respect to the ground and a link rigidly connected between the weight and the fastener for transferring substantially all motion of the weight to the fastener.  
           [0018]    The invention further comprises a method of latching and unlatching a container by changing the orientation of the container with respect to the ground including the steps of providing a container having a lid, providing a fastener shiftable between a first position for securing the lid to the container and a second position for releasing the lid, mounting a weight on the container to pivot bi-stably between first and second positions in response to changes in the orientation of the container, positively coupling the weight to the fastener, pivoting the container in a first direction until the weight shifts to the second position, dumping the contents of the container and pivoting the container from the second position to the first position until the weight shifts to the first position. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]    These and other objects and advantages of the invention will be better understood from a reading and understanding of the following detailed description of the invention together with the following drawings.  
         [0020]    [0020]FIG. 1 is a side elevational view of a container with a gravity-operated latch in accordance with the present invention oriented in an upright, resting position.  
         [0021]    [0021]FIG. 2 is a top plan view of the container of FIG. 1 with the container lid in an open position.  
         [0022]    [0022]FIG. 3 is a side elevational view of the container of FIG. 1 showing the container tilted at about an 85 degree angle from the resting position.  
         [0023]    [0023]FIG. 4 is a side elevational view of the container of FIG. 1 showing the container tilted at about a 90 degree angle from the resting position.  
         [0024]    [0024]FIG. 5 is a side elevational view of the container of FIG. 1 showing the container tilted at about a 105 degree angle from the resting position.  
         [0025]    [0025]FIG. 6 is a side elevational view of the container of FIG. 1 showing the container tilted at about a 150 degree angle from the resting position.  
         [0026]    [0026]FIG. 7 is a side elevational view of the container of FIG. 1 showing the container tilted back to about a 60 degree angle after reaching the orientation shown in FIG. 6.  
         [0027]    [0027]FIG. 8 is a side elevational view of a trash truck with a lift arm engaging the container of FIG. 1.  
         [0028]    [0028]FIG. 9 is a side elevational view of the trash truck of FIG. 8 with the lift arm holding the subject container at a 90 degree angle.  
         [0029]    [0029]FIG. 10 is a side elevational view of the trash truck of FIG. 8 with the lift arm holding the container in a dumping position over an opening in the trash truck. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0030]    Referring now to the drawings, wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only, and not for the purpose of limiting same, FIGS. 1 and 2 show a container  10  according to the present invention which includes a body portion  12  and a lid  14  connected to the body by a hinge  16 . Lid  14  includes a rear section  18  connected to body  12  by the hinge, a front section  20 , a top wall  22 , preferably outwardly curved to keep water from pooling thereon, a sidewall  24  depending from the top and a bottom wall  26 . Bottom wall  26  includes a rear portion  28  adjacent hinge  16 , first and second side portions  30  extending away from rear portion  28  and a front portion  32  connecting the side portions. Side portions  30  each include an opening  34  near front portion  32  having an interior wall  36  on which a pin  38  is mounted, which pins are engaged by fasteners to be described hereinafter for holding lid  14  securely against body portion  12 .  
         [0031]    Container body portion  12  includes a bottom  44 , a sidewall  46  extending upwardly from the bottom, a top wall  48  extending outwardly from the top edge of sidewall  46  to define a top container opening  50 , and a flange  52  depending from the outer edge of top wall  48 . Top wall  48  includes first and second openings  54  near the front section  20  of the container which are aligned with openings  34  in lid  14  when the lid is closed and lid bottom wall  26  rests on body top wall  48 . First and second sleeves  56  are attached at opposite portions of sidewall  24  for receiving the fingers of a trash truck lift arm and allowing the container to be lifted. The sleeves are parallel to one another, generally normal to the axis of hinge  16  and include open front portions which face the front of the container and top walls  58  that are generally horizontal when the container is in its normal rest orientation with bottom wall  44  facing the ground or other support surface and top opening  50  facing generally upwardly.  
         [0032]    The container includes first and second latching mechanisms, one on each side of the container body. Only one latching mechanism is described and shown herein in detail, it being understood that the latching mechanism on the opposite side of the container is substantially identical to and functions in the same manner as the first mechanism.  
         [0033]    A mounting plate  60  is attached to top wall  58  and a bottom stop  62  is mounted thereon. A top stop  64  is mounted between flange  52  and sidewall  24  directly above bottom stop  62 . A triangular bracket  66  is mounted on mounting plate  60  forwardly of bottom stop  62 , and includes a pair of spaced openings  67  that align with opening  68  in a weight  70  which openings receive a pin  72  to secure the weight to the bracket. Weight  70  comprises a triangular body portion  74  and a polygonal head portion  76  attached thereto or that alternately may be formed integrally therewith. Body portion  74  includes a first side wall  78  connected to the head portion of the weight, a second sidewall  80 , a third side wall  82  and front and rear walls  84 . Spaced openings  67  overlie front and rear walls  84  near the meeting point of second sidewall  80  and third sidewall  82  opposite first sidewall  78 , and second sidewall  80  includes a slot  86  having opposed sidewalls  88  each having a journal opening  90  for supporting the opposite ends of a pin described hereafter. Head portion  76  includes a first wall  92  joined to first sidewall  78  of the body portion, a second wall  94  longer than and parallel to first wall  92 , a third wall  96  extending from second wall  94  and a fourth wall  98  extending from first wall  92  and meeting third wall  96  at a 90 degree angle, a fifth wall  100  parallel to third wall  96  and coplanar with body portion third sidewall  82  and a sixth wall  102  connecting second wall  94  to fifth wall  100 . As will be appreciated from the description of the operation of the subject invention, the shape of weight  70  and the location of its center of gravity  101  with respect to the pivot point formed at pin  72  helps control the movement of the weight and also provides for the multiplication of forces exerted on a container latching mechanism.  
         [0034]    A pin  106  projects from sidewall  24  under top wall  48  and beneath lid pin  38 . A latch  108  having a central opening  110  is mounted on pin  106  with pin  106  pivotally supporting the latch and extending though the latch central opening. The latch includes an attachment portion  112  on one side of central opening  110  and a hook portion  114  on the opposite side of the central opening. A connecting rod  116  includes a first end plate  118  having an opening  120  and a second end plate  122  having an opening  124  connects weight  70  to attachment portion  112  of latch  108 . First end plate  118  of rod  116  extends into slot  86  in weight  70  and is attached thereto by a pin  126  having ends supported in journal openings  90  and passing through opening  120  in plate  118 . Second end plate  122  is pivotally attached to an opening  128  in attachment portion  112  of latch  108  by a pin  130 . Preferably the connecting rod is adjustable in length to that it can be adapted to containers of various sizes.  
         [0035]    Hook portion  114  is dimensioned to engage pin  38  on lid  14  when the lid is closed. As will be appreciated from the foregoing description, when fifth wall  100  of weight  70  rests on bottom stop  62 , hook portion  114  of latch  108  is held in engagement with pin  38 . Weight  70  must be moved so that second wall  94  approaches top stop  64  in order to disengage hook  114  from pin  38  and allow the lid to open. Thus forces from inside the body (caused by compacted trash in the container, for example) pressing up against the lid do not move the latch, and the latch holds the lid securely closed even under significant internal pressures. Furthermore, when latch  108  is engaged with pin  38 , the inner edge  132  of hook portion  114  is angled with respect to top wall  48  of the container, and thus as hook  114  passes over pin  38  into the latching position, the rotation of the latch exerts a downward force on pin  38  tending to hold lid  14  very securely shut.  
         [0036]    In operation, trash is loaded into container  10  through a side opening (not shown) by a compactor (not shown). When the container is ready to be emptied, it is disconnected from the compactor. A trash truck  140  having a lift arm  142  with fingers  144  approaches the container and inserts fingers  144  into sleeves  56  on either side of the container body, and the container is lifted through an upward arc toward an opening  146  in truck  140  into which trash will be discharged. FIGS.  8 - 10  show the movement of the container from a resting orientation on the ground to a dumping orientation over opening  146 .  
         [0037]    The orientation of the container will be described in terms of the angle between a container reference line extending normal to the plane of top opening  54  and a line normal to the ground. When the container is in a resting orientation with the sidewalls generally vertical and the top opening facing generally in an upward direction, the container is positioned at a 0 degree angle and weight  70  is supported by bottom stop  62  and holds latch  114  in engagement with pin  38  on lid  14 .  
         [0038]    [0038]FIG. 3 shows the container positioned at about an 85 degree angle. As can be seen from this figure, the center of gravity  101  of weight  70  still lies between a pivot point at pin  72  and bottom stop  62  and thus weight  70  continues to lie against the bottom stop. However, as shown in FIG. 4, when the container reaches the 90 degree position, the center of gravity of weight  70  moves to the other side of its pivot point, and weight  70  falls against top stop  64  moving rod  116  toward container top wall  48  and pivoting latch  114  to disengage hook  116  from pin  38 .  
         [0039]    [0039]FIG. 5 shows container  10  angled at 105 degrees with respect to the vertical, and in this position, lid  14  swings open under the force of gravity and under the weight of the trash inside the container as it falls toward the opening. Substantially all trash should fall out of container when it is tipped to a 150 degree angle shown in FIG. 6.  
         [0040]    After reaching the dumping orientation shown in FIG. 6, the container is pivoted back toward the 0 degree resting orientation. When the container passes the 90 degree orientation, lid  14  comes into contact with top wall  48  of the container. However, as shown in FIG. 6, even when the container is at a 60 degree orientation shown in FIG. 7 and lid  14  rests on the top wall of the container, weight  70  remains resting on top stop  64  because center of gravity  101  remains on the top stop side of pivot point  72 . Not until the container pivots past about a 45 degree orientation does weight  70  tip back against bottom stop  62  and pull hook  114  back into engagement with pin  38 .  
         [0041]    Advantageously, the shape and mounting of weight  70  described above causes it to shift from the bottom stop to the top stop at a first angular orientation and return from the top stop to the bottom stop at a second orientation. Thus, when dumping a full container, the lid can be held in a closed position until at least a 90 degree orientation to keep trash from prematurely spilling from the container. However, the latch does not reengage pin  38  until the container is more upright and lid  14  is resting solidly on top wall  48  of the container body under the force of gravity. This bi-stable mounting of weight  70  ensures that the latch is either completely engaged or disengaged, and the positive coupling between the weight and the latch, as well as the distance between the center of gravity of weight  70  and the pivot point  72  helps maximize the force applied to rod  116  when the weight begins to move.  
         [0042]    The subject invention has been described in terms of a preferred embodiment, it being understood that obvious modifications and additions to the invention will become apparent to those skilled in the relevant arts upon a reading an understanding of this disclosure. It is intended that all such obvious modifications and additions be included in the subject invention to the extent that they are covered by the several claims appended hereto.

Technology Classification (CPC): 8