Patent Publication Number: US-2012043768-A1

Title: Magnetic latch assembly

Description:
This invention relates to a magnetic latch assembly. More particularly, this invention relates to a magnetic latch assembly for a refrigerated cabinet. 
     As is known, various types of latching means have been provided for maintaining doors in a closed position relative to a cabinet and like structures. In some cases, the latching means have been of a magnetic type. For example, a magnetic latch assembly is known for a door that is hinged on one side and mounted on a cabinet for swinging between a closed position and an open position relative to the cabinet. The magnetic latch assembly is secured to a side of the door to cooperate with a magnet mounted in the frame of the cabinet in order to maintain the door in the closed position. The magnetic latch assembly is constructed to have a flat plate rest against the cabinet frame in a position directly opposite the magnet and be magnetically attracted by the magnet as well as a handle that can be manually grasped to pull open the door. Generally, this arrangement requires a great deal of force to pull open the door. This force cannot be decreased since the magnet might not then be sufficient to keep the door closed, particularly, on a ship where rough seas could cause the door to open. 
     Accordingly, it is an object of the invention to provide a magnetic latch assembly for a door that can be easily manipulated to open the door. 
     It is another object of the invention to provide a magnetic latch assembly that can be manipulated in a manner to facilitate opening of a door. 
     It is another object of the invention to significantly reduce the force required to open a magnetic latch on a door. 
     Briefly, the invention provides a magnetic latch assembly that can be mounted to a side of a door for magnetically locking with a magnet located at a predetermined position of a door frame and pivoted relative to the side of the door and the magnet. Typically, the door and the door frame are made of non-magnetic material, e.g. 300 series stainless steel. 
     Typically, the door is mounted on the door frame for movement towards and away from the frame. In this regard, the door is typically mounted in a hinged manner for a pivoting movement to bring the latch assembly opposite the magnet. 
     The latch of the assembly is of generally conventional structure having a first flat face for mounting on the side of the door in facing relation, a second flat face perpendicular to the first face for facing the magnet on the door frame and a curved handle extending from the first face to overlie the door on a side opposite the magnet. 
     In accordance with the invention, the latch assembly has a bracket that is secured to the side of the door in a stationary manner between the first flat face of the latch and the side of the door and the latch is pivotally mounted on the bracket to pivot relative to the door and relative to the magnet in response to a pulling force on the curved handle sufficient to move the door from the closed position away from the frame. In this regard, the second flat face of the latch, i.e. the face opposed to the magnet, has an edge in contact with the door frame for pivoting thereon during pivoting of the latch relative to the bracket and door. 
     In order to provide for pivoting of the latch, the bracket has a protrusion of circular shape and the latch includes an opening in the first flat face that receives the protrusion in mating relation for pivoting of the latch thereon. In addition, the protrusion is provided with a bore for passage of the shank of a bolt that serves to secure the bracket to the side of the door. A washer is also provided between the head of the bolt and the latch to not only cover over the opening in the latch to keep dirt and debris out to meet sanitary standards but also to hold the latch between the washer and the bracket in a slide fit manner so that the latch may be pivoted relative to the bracket while being held in place between the washer and the bracket. 
     In order to limit the degree of pivoting of the latch, the bracket has a second protrusion spaced from the first protrusion and the latch includes a second opening in the first flat face for receiving this second protrusion. In this respect, the second protrusion is smaller than the second opening in the latch so that the latch is able to move relative to the second protrusion during pivoting of the latch relative to the door. 
     As above, the second protrusion is provided with a bore for passage of the shank of a second bolt that serves to secure the bracket to the side of the door in a fixed position. In addition, as above, a second washer and a second bolt are provided to secure the latch to the door while allowing for pivoting of the latch relative to the bracket. 
     The latch is made of magnetically attractive material so as to be attracted by the magnet in the non-magnetic door frame so that the door may be maintained in a closed position under the magnetic forces created between the latch and the magnet. 
     The latch may be constructed so that the curved handle is disposed below the plane of the magnet in the cabinet frame as well as below the first flat face that pivots relative to the bracket secured to the side of the door. This increases the lever arm for a manual pulling force imposed on the latch when the door is to be opened away from the door frame. 
     When in use, upon closing of a door, the magnet in the cabinet attracts the flat face of the latch facing the magnet so as to pull the face into parallel alignment, and thus the latch, with the magnet. 
     In order to open the door, the handle of the latch is manually grasped and pulled. At this time, the latch first begins to pivot relative to the bracket in the side of the door while the uppermost edge of the latch remains in contact with the door frame and pivots thereon. During this time, the flat face of the latch facing the magnet is gradually “peeled” away from the magnet, i.e., pivots relative to the magnet creating a gap therebetween. This, in turn, reduces the magnetic attraction forces between the latch and the magnet allowing the door to be swung away from the magnet into an open position. In this way, the latch is pried at an angle to the magnet rather than being pulled straight away from the magnet. This significantly reduces the pull required to free the latch from the magnetic force. 
     The latch assembly may be made with a latch constructed for right-hand use or left-hand use. 
     The latch may also be constructed in a universal manner for right-hand use or left-hand use. In this embodiment, the latch has a pair of flat faces for selectively facing the side of a door, a second pair of flat faces facing the door frame and being angled relative to each other with only one of these flat faces having an edge in contact with the door frame as well as a pair of curved handles. Each handle is disposed opposite a respective one of the first pair of flat faces and extends over the door on a side opposite the magnet. 
     In this embodiment, the two flat faces that are to face the side of the door are provided with a total of three openings, only two of which are used for mounting of the latch on a bracket secured to a door. In this respect, the center opening and the upper opening are used for a right hand door while the center opening and the bottom opening are used for a left hand door. 
     In each case, the uppermost opening in the latch is pivotally mounted on the upper protrusion of the bracket to allow pivoting of the latch relative to the bracket. The center opening receives the other protrusion of the bracket in spaced relation to limit the pivoting movement of the latch. 
    
    
     
       These and other objects and advantages of the invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings wherein: 
         FIG. 1  illustrates a schematic view of a door mounted on a door frame with a latch assembly in accordance with the invention; 
         FIG. 2  illustrates an exploded view of the latch assembly of  FIG. 1 ; 
         FIG. 3  illustrates a side view of the latch assembly in a closed position on a door frame; 
         FIG. 4  illustrates a side view of the latch assembly similar to  FIG. 3  during an initial opening phase of the latch assembly relative to a door frame; 
         FIG. 5  illustrates a back-side view of the latch assembly in the closed position corresponding to  FIG. 3 ; 
         FIG. 6  illustrates a back-side view of the latch assembly in the partially open position corresponding to  FIG. 4 ; 
         FIG. 7  illustrates a part cross-sectional view taken on line  7 - 7  of  FIG. 5 ; and 
         FIG. 8  illustrates a view of a latch for right-hand use or left-hand use. 
     
    
    
     Referring to  FIG. 1 , the latch assembly  10  is mounted on the side of a door  11  that is hinged on the opposite side to a door frame  12 , for example, by two or more hinge assemblies (not shown). 
     The door  11  is made of a conventional structure and the door frame  12  is made of any conventional structure having a magnet  13  embedded within the structure. 
     The latch assembly  10  includes a latch  14  of conventional structure that has a first flat face  15  facing the side of the door  11  and a second flat face  16  perpendicular to the first flat face  15  that faces the magnet  13  in the door frame  12 . At least this second flat face  16  is made of magnetic material so as to be magnetically attracted to the magnet  13  in order to maintain the door  11  in a closed position on the door frame  12 . 
     The latch  14  also has a curved handle  17  that extends from the first flat face  14  on a side opposite the second flat face  16  to extend over the door  11  as illustrated. This handle  17  is sized so as to be manually grasped by a user so that the door  11  may be pulled from the door frame  12 . The curved handle  17  is disposed below the plane of the magnet  13  in the door frame  12  as well as below the first flat face  16 . 
     Referring to  FIG. 2 , the latch assembly  10  also includes a bracket  18  of rectangular shape that is adjustably secured in a stationary manner to the side of the door  11  between the latch  14  and the door  11 . 
     The bracket  18  has a pair of circular protrusions  19 ,  20  facing the latch  14 , each of which is provided with an elongated bore  21 ,  22 . The protrusions  19 ,  20  are aligned on a common longitudinal axis of the bracket  18 . In addition, the upper protrusion  19  is made with a diameter larger than the diameter of the lower protrusion  20 . 
     The latch  14  is provided with a pair of apertures  23 ,  24  of identical size that are aligned with the protrusions  19 ,  20  of the bracket  18 . The upper aperture  23 , as viewed, is sized to receive the upper protrusion  19  of the bracket  18  with a small working clearance and in rotatable manner so that the latch  14  may be pivoted on the fixed bracket  18 . The lower protrusion  20  of the bracket  18  is of smaller size than the lower aperture  24  of the latch  14  to accommodate pivoting of the latch  14  on the bracket  18  and to limit the degree of pivoting of the latch  14 . 
     The latch assembly  10  also has a pair of bolts  25  and a pair of washers  26  that clamp the bracket  18  tightly to the side of the door  11  after adjustment and seat against the faces of the protrusions  19 ,  20  that project through the latch  14 . The thickness of these protrusions  19 ,  20  is such that the latch  14  is retained closely but is still free to be rotated about the outer surface of the upper protrusion  19 . 
     The washers  26  are of a size sufficient to cover over the apertures  23 ,  24  in the latch  14  while each bolt  25  has a shank  27  that passes through a washer  26 , the latch  14  and a respective aperture  21 ,  22  in a protrusion  19 ,  20  of the bracket  18  into suitable bores  28  in the side of the door  11 . Each bolt  25  has a head  29  that abuts against a washer  26  with a force sufficient to secure the bracket  18  to the side of the door  11  and yet with sufficient clearance to allow pivoting of the latch  14  relative to the bracket  18 . When the latch  14  is secured to the bracket  18 , the latch  14  is free to pivot about the upper protrusion  19  under a manually applied pulling force on the latch handle  17 . 
     Referring to  FIG. 3 , when the latch assembly  10  is in a closed position relative to the door frame  12 , the flat front face  16  is parallel to and opposite the magnet  13 . Due to the magnetic attraction between the face  16  of the latch and the magnet  13 , the door remains in this position. 
     Referring to  FIG. 4 , wherein like reference characters indicate like parts as above, when the handle  17  of the latch  14  is manually grasped and initially pulled, the latch  14  pivots about the axis of the upper bolt  25  and the upper protrusion  19  (see  FIG. 2 ) of the bracket  18  (not shown) causing the bottom edge of the face  16  to pull or peel away from the door frame  12  while the upper edge of the face  16  pivots on the door frame  12  thus forming an angle A between the face  16  and the door frame  12 . During this time, the magnetic force between the magnet  13  and the face  16  is sufficiently strong to allow the pivoting of the latch  14  without releasing the latch  14  from the door frame  12 . 
     The manual pulling force required to free the latch  14  from the magnetic force of the magnet  13  is thus significantly reduced by this rotation. 
     The lower protrusion  20  of the bracket  18  being significantly smaller than the upper protrusion  19  and the aperture  24  permits the arcuate motion of the latch  14  but limits the motion upon contacting the rim of the aperture  24 . 
     The slots  21 ,  22  in the bracket  18  may be elongated to allow for adjustment of the bracket  18  on the side of the door  11  so that the amount of compression on a rubber door gasket (not shown) can be adjusted. 
     Referring to  FIG. 5 , the back of the latch  14  is provided with an abutment  30  to position the latch  14  parallel to the door  11  and the bracket  18  at the initial adjustment. 
     Referring to  FIGS. 5 and 7 , during the final installation of the latch  17 , the bolts  25  are loosely mounted to pass through the latch  17  and bracket  18  into the door  11 . Thereafter, the door  11  is closed so that the force of the magnet  13  in the door frame  12  holds the face  16  of the latch  14  against the door frame  12 . At this time, the magnetic force of the magnet  13  and the force of a compressed rubber door gasket (not shown) against the door  11  and, thus, against the bolts  25  and bracket  18 , keep the abutment  30  on the latch  14  firmly held against the side of the bracket  18  farthest from the magnet  13  (not shown) at one “contact point” as well as moving the sidewall of the upper aperture  23  of the latch  14  into contact with the protrusion  19  on the bracket  18  at a second “contact point”. The latch  14  thus becomes parallel to the bracket  18  and to the magnet  13  on the door frame  12 . The bolts  25  are then tightened to secure the latch  14  in this condition. 
     Thus, with the bolts  25  in a loosened state and the door  11  pushed against the frame  12  to get the proper compression of the rubber door gasket (not shown), the two points of contact, i.e., the point of contact of the larger protrusion  19  against the rightward surface of the aperture  23 , as viewed in  FIG. 2 ) and the point of contact of the rightmost edge of the bracket  18  against the abutment  30 , establish the verticality of the bracket  18 . The two bolts  25  are then tightened to maintain this compression and the bracket  18  remains parallel to the door  11 , restrained in position by the two aforementioned points of contact, and thus keeps the latch  17  aligned parallel to the magnet in the door frame  12 , without any free play, all slack being taken up by the compressive force of the gasket against the latch  12 . 
     Referring to  FIG. 6 , when the door is being opened, an outward force on the latch  14  causes the latch  14  to rotate about the upper protrusion  19  (see  FIG. 2 ). As this force is applied, the upper edge of the lever  14  pushes against the door frame  12  and angularly breaks the latch  14  free from the magnet  13  as indicated in  FIG. 4 . When the latch  14  has been rotated to its extreme position on the bracket  18  during opening of the door  11 , the lower protrusion  20  abuts the inner surface of the aperture  24  in the latch  14 , i.e. the aperture surface closest to the door frame  12 , and stops further rotation of the latch  14 . 
     Referring to  FIG. 8 , the latch  35  may be made for universal use or right-hand use or left-hand use. As shown, the latch  35  has a first pair of flat faces  36  for selectively facing a side of a door, a second pair of flat faces  37  for facing a door frame with one of the flat faces  37  having an edge thereof in contact with the door frame for pivoting thereon during pivoting of the latch  35  relative to the door and a pair of curved handles  38 . Each handle  38  is disposed opposite a respective one of the first pair of flat faces  36  and is to extend over the door on a side opposite a magnet. A pin (not shown) may be mounted in the latch  35  for the same purpose as the protrusion  30 . 
     As shown, the flat faces  37  for facing a magnet are angularly disposed so that only one of these faces  37  may lie against a door frame when in use. 
     In this embodiment, the two flat faces  36  that are to face the side of the door are provided with a total of three openings  39 ,  40 ,  41  only two of which are used for mounting of the latch  35  on a bracket  18  (not shown) secured to a door. In this respect, the center opening  40  and the upper opening  39  are used for a right hand door while the center opening  40  and the bottom opening  41  are used for a left hand door. 
     In each case, the uppermost opening in the latch  35  is pivotally mounted on the upper protrusion  19  of the bracket  18  (see  FIG. 2 ) to allow pivoting of the latch  35  relative to the bracket  18 . The center opening  40  receives the other protrusion  20  of the bracket  18  in spaced relation to limit the pivoting movement of the latch  35 . 
     The invention thus provides a magnetic latch assembly for a door that can be easily manipulated to open the door and that can significantly reduce the force required to open the door.