Abstract:
A shelf lift system includes a pair of support brackets fixed to sidewalls of a cabinet, each bracket having first and second pivots and a swing linkage having first and second bars coupled to the pivots. Shelf supports are coupled to the first and second bars to support a common shelf for movement between an upper position generally coplanar with the cabinet top surface and a lower position situated fully within the cabinet below the top surface. An adjustment plate adjusts the force applied by a biasing member. A latch coupled to each shelf support engages a latch pin coupled to one of the first and seconds bars when the shelf is in the upper position. A latch release lever releases the latch to allow the shelf to move to the lower position. A cushion is fixed to the support bracket at a position to intercept a stop contact portion near the end of one of the bars when the shelf support moves to the lower position.

Description:
BACKGROUND  
       [0001]     1. Technical Field  
         [0002]     A shelf lift system for use in a cabinet structure employing a swingable linkage for moving a shelf between a lower position, which is situated within a cabinet and under a generally horizontal top surface of the cabinet, and an upper position, which is situated generally coplanar with the top surface, and for selectively maintaining the shelf in the lower and upper positions.  
         [0003]     2. Background Information  
         [0004]     Many people prefer to maintain their residential kitchen counter tops as free from clutter as possible. Kitchen appliances that are not in current use are preferred to be stored out of sight. Such storage is easily accomplished for most light weight appliances. For heavier appliances, such as electric mixers and bread making machines, the movement between a cabinet storage position and the counter top can be awkward and difficult. Swinging shelf supports are known that can be used to move a shelf bearing such an appliance between a storage location within a cabinet under a counter top and a use position at substantially counter top level.  
         [0005]     Carlson U.S. Pat. No. 2,822,229 discloses such a swinging shelf support having of a pair of mechanisms, which are mirror images of each other, supporting the opposite sides of a shelf. Each mechanism includes a bracket having two pivot pins, affixed to a cabinet sidewall. One end of each of two arms is connected, respectively, to each of the pivot pins. The opposite ends of the two arms are pivotally connected to a plate that is affixed to the bottom of the shelf so that the two arms are maintained parallel to each other during movement of the shelf. A rib projects from the plate that limits the range of movement of the arms so that the shelf can move from a storage position within the cabinet and an upper position somewhat below the top surface of the cabinet. A tension spring extends between the bracket and a stud adjustably positioned on one of the two arms to provide a biasing force assisting the upward movement of the shelf. During movement of the shelf toward the upper position, one of the arms displaces a strip spring shaped to include a projecting portion that can engage an upper surface of the arm. A single trigger is wired to the strip springs to cause disengagement of the projection portion so that the shelf can be lowered to the storage position. During movement of the shelf toward the storage position, the tension spring moves to an opposite side of one of the pivots so that the spring applies a retaining force to retain the shelf in storage.  
         [0006]     While the basic design disclosed by Carlson is excellent, it does have some shortcomings. For example, the Carlson swinging shelf support is not capable of locating the shelf in the same plane as the top of the cabinet in which the support is mounted. The Carlson shelf support also includes a latch mechanism that is easily accidentally unlatched so that the shelf can suddenly descend from the raised position. The Carlson shelf support stop mechanism can abruptly halt downward movement of the shelf so that a shock or impact is delivered to any attachments between the bracket and the cabinet that can contribute to attachment failure. The Carlson shelf support spring adjustment can easily become disengaged so that the desired amount of biasing force is surprisingly no longer available. Some of the shortcomings of the Carlson design have been previously addressed in other prior art.  
         [0007]     Some prior art swinging shelf supports, such as Hafele lift-up mechanism models 504.24.701 and 504.24.710, are capable of locating the shelf in the same plane as the top of the cabinet in which the support is mounted, but still share some of the other shortcomings of the Carlson design. Thus, there remains a need for a swinging shelf support system that eliminates all of the shortcomings of the Carlson design.  
       SUMMARY OF THE INVENTION  
       [0008]     A swinging shelf support system of the present invention includes a pair of shelf lift mechanisms that are mirror images of each other and intended to support opposite sides of a shelf for movement with respect to a cabinet having a generally planar counter top. Each shelf lift mechanism has a support bracket with a first and a second pivot coupled to the bracket. A first bar and a second bar are respectively coupled to the first and second pivots for movement relative to the support bracket. A shelf support is coupled to the first and second bars for movement with the bars relative to the bracket between an upper position wherein the shelf is essentially coplanar with the adjacent counter top and a lower position fully within the cabinet below the counter top. A biasing spring provides a balancing force to offset the weight of the shelf and any appliance or other mass situated on the shelf so that movement of the shelf between the two positions is easily accomplished.  
         [0009]     One feature of a shelf lift system of the present invention is a cushion fixed to the support bracket at a position designed to intercept a stop contact portion of one of the first and second bars when the shelf support moves to the lower position. The cushion is preferably made of rubber with a durometer of between about 40 and 70 Shore A. The cushion is preferably located between the first and second pivots on the support bracket so that an extension of one of the bars can constitute the stop contact portion.  
         [0010]     Another feature of a shelf lift system of the present invention is a tension adjustment member that is coupled to one end of the biasing spring and pivotally connected to one of the first and second bars. The adjustment member includes a handle facilitating adjustment of the biasing force and a plurality of openings designed to receive a fastener to securely position the adjustment member at a suitable position to apply a selected biasing force to compensate for the various appliances or other goods on the shelf.  
         [0011]     Yet another feature of a shelf lift system of the present invention is a latch coupled to the shelf support and a latch pin coupled to one of the first and second bars at a position that permits engagement of the latch pin and latch when the shelf support is in the upper position. A latch release lever including a handle is coupled to the latch, each handle being independent from the corresponding latch release for the coordinate shelf lift on the opposite side of the shelf. A biasing spring is coupled to the latch to bias the latch toward engagement with the latch pin so that accidental release of either latch is rendered unlikely.  
         [0012]     Additional features of a shelf lift system of the present invention will become apparent from a consideration of the following description of a preferred embodiment shown in the accompanying drawings that illustrate the best mode of carrying out the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  is a perspective view, partly broken away, showing a shelf lift system of the present invention with the shelf in a lower position.  
         [0014]      FIG. 2  is a perspective view showing the shelf lift of  FIG. 1  with the shelf in an upper position, the door being omitted for clarity.  
         [0015]      FIG. 3  is an elevation view of a first side of a shelf lift mechanism of the present invention.  
         [0016]      FIG. 4  is an elevation view of a second side of the shelf lift mechanism shown in  FIG. 3 .  
         [0017]      FIG. 5  is a detail view of a support bracket including an absorbing cushion and the biasing adjustment plate.  
         [0018]      FIG. 6  is a detail view of the shelf support bracket showing the latch mechanism.  
         [0019]      FIG. 7  is a detail view of the support bracket shown in  FIG. 5  with the swinging arms moved to the lower position.  
         [0020]      FIG. 8  is an elevation view of a biasing adjustment plate.  
         [0021]      FIG. 9  is a detail view of the opposite side of the shelf support bracket shown in  FIG. 6 .  
         [0022]      FIG. 10  is a perspective view of the latch shown in  FIGS. 6 and 9 .  
         [0023]      FIG. 11  is a perspective view of a shelf lift mechanism of the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0024]     A swinging shelf support system  10  of the present invention is shown in  FIGS. 1 and 2 . The shelf support system  10  includes a pair of shelf lifts mechanisms  12 , which are generally mirror images of each other, intended to support opposite sides  14  of a shelf  16  for movement with respect to a cabinet  18  having a generally planar counter top  20  including top surface  21 . The cabinet  18  can include a base  22  having a floor shelf  24 , a back wall  26 , and side walls  28  and  30 . A perimeter frame  32  defines an opening opposite the back wall  26 . A door  34  can be coupled to the perimeter frame  32  with hinges  36  to control access to the interior of the cabinet  18 . The counter top  20  can be secured to upper ends of the back wall  26 , the side walls  28  and  30 , and the perimeter frame  32 . The counter top can cover merely the space between the side walls  28  and  30 , but may also extend laterally to cover additional cabinets, not shown.  
         [0025]     The shelf  16  can include a bottom surface  38  and a top surface  40 . The shelf  16  can also include a back margin  42  and front margin  44 , which may include a portion projecting above the top surface  40  of shelf  16 . The shelf  16  must be laterally narrower than the opening defined by the perimeter frame  32  to permit movement of the shelf  16  out of and into the cabinet  18 . With the door  34  open, the shelf  16  can be moved with the aid of swinging shelf support system  10  of the present invention, between a lower position wherein the shelf  16  is wholly contained within the cabinet  18 , shown in  FIG. 1 , and an upper position wherein the top surface  40  of the shelf  16  is substantially coplanar with the top surface  21  of the counter top  20 , shown in  FIG. 2 . Each shelf lift mechanism  12  includes a support bracket  46 , which is secured to the cabinet  18 . The support bracket  46  can be secured to a side wall  28  or  30  of the cabinet  18 . Each support bracket  46  includes a forward pivot  48  and a rearward pivot  50 . A forward bar  52  is coupled to the forward pivot  48  and a rearward bar  54  is coupled to the rearward pivot  50 . Each mechanism  12  of the shelf support system  10  of the present invention also includes a shelf support  56  that can be secured to the bottom surface  38  of the shelf  16 . The shelf support  56  also includes a forward pivot  58  and a rearward pivot  60 . The forward bar  52  is coupled to the forward pivot  58  on the shelf support  56 , and the rearward bar  54  is coupled to the rearward pivot  60  as shown in  FIGS. 2, 4 , and  6 . The forward and rearward bars  52  and  54  simultaneously swing between the lower and upper positions, shown in  FIGS. 1 and 2 , respectively, while maintaining the top surface  40  of the shelf  16  generally parallel to the top surface  21  of counter top  20 .  
         [0026]      FIGS. 3 through 11  show additional details of a shelf lift mechanism  12  of the present invention. In  FIGS. 3 through 5  and  7 , it will be seen that the support bracket  46  can include a generally planar central portion  62  separating forward edge flange  64  and rearward edge flange  66 , which may be located in a plane other than the central portion  62  as shown in  FIG. 11 . The flanges  64  and  66  and connected to the central portion  62  by webs  63 . The flanges  64  and  66  can include any number of openings  68  to receive fasteners for fastening the support bracket  46  to the cabinet  16 . The forward pivot  48  and the rearward pivot  50  can be located in the central portion  62 . The forward pivot  48  can be positioned near an upper edge  70  of the central portion  62  while the rearward pivot  50  can be positioned near a lower edge  72 . A bias anchor  74  can be provided on the central portion  62  of the support bracket  46 . The bias anchor  74  can project from the central portion  62  in the same general direction as the webs  63 , toward the sidewall  28  of the cabinet  18 . A cushion support  76  can be fixed to the central portion  62  of the support bracket  46  roughly between the forward pivot  48  and the rearward pivot  50 . A cushion  78  can be fixed to the cushion support  76  so that an end  77  protrudes from the cushion support  76 .  
         [0027]     The forward bar  52  includes a first end  80  and a second end  82 . The first end  80  of the forward bar  52  can be coupled to the forward pivot  48  on the central portion  46  of the support bracket  46 . The second end  82  of the forward bar  52  can be coupled to the pivot  58  on the shelf support  56 . The rearward bar  54  also includes a first end  84  and a second end  86 . The second end  86  can be coupled to the pivot  60  on the shelf support  56 . The rearward bar  54  can also include an intermediate pivot coupling point  88  spaced from the first end  84 . The intermediate pivot coupling point  88  on the rearward bar  54  can be coupled to the rearward pivot  50 . A portion  90  of the rearward bar located between the intermediate pivot coupling point  88  and the first end  84  can come into contact with the protruding end  77  of cushion  78  when the shelf  16  is in the lower position as shown in  FIGS. 1 and 7 .  
         [0028]     The rearward bar  54  can also include a tension adjustment support  92  located between the second end  86  and the intermediate pivot coupling point  88 . A tension adjustment member  94 , which can include a handle  96  to facilitate adjustment of the position of member  94 , can be pivotally coupled to the tension adjustment support  92 . The tension adjustment member  94  includes a bias post  98 . A biasing member  100  in the form of a tension spring can be extended between the bias post  98  on the tension adjustment member  94  and the bias anchor  74  on the central portion  62  of the support bracket  46 . As shown particularly in  FIG. 8 , the tension adjustment member  94  can include an opening  102  for pivotally coupling the adjustment member  94  to the tension adjustment support  92  on the rearward bar  54 . The tension adjustment member  94  can also include a plurality of openings  104  that can be selectively engaged by a fastener  106 . The selection and engagement of one of the plurality of openings  104  by a fastener  106  creates an initial bias value for the tension applied by the biasing member  100 .  
         [0029]      FIGS. 9-11  show that shelf support  56  can include a lateral flange  108 . A plurality of openings  110  are provided in the lateral flange  108  to receive any number of fasteners for fastening the flange to the bottom surface  38  of the shelf  16 . The shelf support  56  also includes a forward pivot  58  and a rearward pivot  60 . The second end  82  of the forward bar  52  is coupled to the forward pivot  58  on the shelf support  56 , and the second end  86  of the rearward bar  54  is coupled to the rearward pivot  60  as shown in  FIG. 6 . When the shelf support  56  is located in the upper position as shown in  FIGS. 3 and 4 , the biasing member  100  is situated above and in front of rearward pivot  50 , and generally aligned with the cushion support  76 . When the shelf support  56  is lowered to the lower position as shown in  FIGS. 1 and 7 , the biasing member  100  moves to a position located behind the rearward pivot  50 . A latching mechanism  112  can be supported on the shelf support  56  for locking the shelf support  56  in the upper position shown in  FIG. 2 .  
         [0030]     The latching mechanism  112  can include a latch pin  114  fixed to the forward bar  52  at a position spaced from the second end  82 , yet overlapping the shelf support  56  when located in the upper position. A latch  116  can be coupled to the shelf support  56  by a pivot pin  118 . The latch  116  is shown in greater detail in  FIG. 10  to include a latch body  120  that can have a concave edge  122  sized to engage the latch pin  114  as shown in phantom in  FIG. 9 . An inclined edge  124  can be positioned above and separated from the concave edge by a nose portion  126 . The body  120  can also have an opening  128  adjacent one end of the body to accept the pivot pin  118  and a lateral protrusion  130  positioned at the opposite end of the body  120 . A latch bias engaging pin  132  extends laterally from one surface of the body  120  and can protrude through an opening  57  in the shelf support  56  shown in  FIG. 9 . A latch bias spring  134  can extend between pin  132  on the latch body  120  and a latch spring anchor pin  136  fixed to the shelf support  56 . The lateral protrusion  130  can also protrude through an opening  55  in the shelf support  56  as shown in  FIG. 6 . The lateral protrusion  130  engages slot  138  in latch release rod  140 . The latch release rod can include slots  142 , which may receive anchor pins  144  fixed to the shelf support  56  that allow for a sliding movement of the latch release rod  140  with respect to the shelf support  56 . The latch release rod  140  can include a handle portion  146  such as that shown in  FIG. 11 .  
         [0031]     In operation, the shelf lift system  10  of the present invention retains the shelf  16  within the cabinet  18  by virtue of the over-center relationship of the biasing spring  100  with respect to rearward pivot  50 . When the load to be supported on shelf  16  is lighter, the force required to be applied by the biasing spring  100  need not be as great as when the load to be supported is heavier. The force applied by the spring  100  to retain the shelf  16  in the position shown in  FIG. 1  can be adjusted by removing fastener  106 , pivoting the adjustment member  94  around adjustment support  92  to a new location, and reinserting fastener  106  into one of the plurality of openings  104 . To move the shelf  16  from the lower position within the cabinet  18  to the upper position wherein the shelf  16  is substantiality coplanar with the counter top  20 , one merely needs to apply sufficient outward force on the front margin  44  of the shelf  16  to pivot the bars  52  and  54  to the point that the biasing spring  100  is displaced to a point in front of rearward pivot  50 , where upon the biasing spring  100  assists in the outward and upward displacement of the shelf  16 .  
         [0032]     As the shelf  16  approaches the upper position from the lower position, the latch pin  114  carried by front bar  52  contacts the upper surface  124  of the latch  116 . Continued upward displacement of the shelf  16  and shelf support  56  causes the latch pin  114  to pivotally displace the latch  116  to the point where the nose  126  passes the latch pin  114 . The latch bias spring  134  then causes a rotational displacement of the latch  116  around pivot  118  until concave edge  122  comes into contact with the latch pin  114  effectively locking shelf  16  in the upper position shown in  FIG. 2 . Since a shelf lift system  10  of the present invention includes a pair of shelf lifts mechanisms  12 , which are generally mirror images of each other, typically there are engaging latches and latch pins supporting both sides  14  of shelf  16 . In the event that only one of the latches and latch pins engage, the shelf is still inhibited from downward displacement by the biasing force of biasing spring  100 , and prohibited from downward displacement by the single engaged latch  116 . The double engagement of both latches  116  and latch pins  114  can be viewed as a safety measure rather than one of necessity for maintaining the shelf  16  in the upper position.  
         [0033]     This safety measure is particularly evident when considering the steps necessary to lower the shelf  16  from the upper position. Assuming that both latches  116  are engaged, an outward force must be applied to the handles  146  of the latch release rods  140  on both sides of the shelf  16 . The force necessary for release is determined by the strength of the latch bias springs  134  and any incidental frictional forces. Any accidental pull on only one of the handles  146  is unlikely to release both latches  116 . When both latches  116  are released, the shelf  16 , together with what ever load has been applied to the shelf, should descend slowly against the biasing force applied by biasing spring  100 . A small downward and inward force may be required to complete the movement of the shelf  16  to the point where the biasing spring  100  passes the rearward pivot  50 . Once past the rearward pivot  50 , the biasing spring  100  acts to continue displacement of the shelf  16  into the cabinet  18  until the stop contact portion  90  of bar  54  contacts the end  77  of cushion  78 . The cushion  78  deforms in response to the contact by the bar  54  to absorb the kinetic energy of the rearwardly moving shelf  16  so that any shock to the cabinet  18  or rebound of the shelf  16  in minimized.  
         [0034]     It is intended that the foregoing description be regarded as illustrative rather than limiting, and that the following claims, including all equivalents, define the spirit and scope of this invention.