Patent Application
20060070212
The present invention relates to a type of hinge that can be used for, among other things, attaching a table leaf to a table top in a drop-leaf table in which the leaf, when not extended, is folded onto the top of the table (a “fold-over/drop-leaf table”).
As described in my prior patent, U.S. Pat. No. 4,928,350, in certain hinge applications it is desirable for the hinge to allow the two objects it joins to be so close together when the hinge is at a certain position in its swing path that there is little or no gap between the objects. An example is a drop-leaf table. When the leaf and the table top are in the coplanar position—i.e., the leaf is extended—it is preferred that there be little or no gap between them.
Often in such drop-leaf table applications it is also preferred that no part of either hinge extend above the top and leaf when in the coplanar position—i.e., that the extended table top be smooth and uninterrupted, particularly uninterrupted by hinge pins that protrude above the surface. This requires that the hinge-pin axes be at an elevation below the upper surface of the table top. Normally that is not a problem if the leaf folds down. But if the leaf is to fold onto the top of the table, it is difficult to accomplish both objectives: positioning the hinge pins below the upper surface and having little or no gap between the top and the leaf when in the coplanar position. When using a conventional hinge, the greater the distance between the sunken hinge-pin axes and the upper surface of the table top, the wider must be the clearance gap between the top and the leaf.
The hinge of the present invention addresses this problem by using a mechanism that causes the joined objects, when being swung away from the close-together position, to also move slightly apart from one another as they pivot. By moving the opposed faces of the two hinged-together objects apart as the objects swing away from the close-together position, there is less need of a clearance gap when in the close-together position. To accomplish this simultaneous translation and pivoting movement, the hinge of the present invention comprises:
Each pin slidably engages one of the guide slots and the pair of pins can simultaneously slide in their respective guide slots. Since the guide slots of each pair of slots are non-parallel, when one pin is forced to slide in one direction, the first assembly is forced to both turn and translate with respect to the link. Thus, if the hinge is at its close-together position and a turning force is applied to the first assembly, the first assembly will not only swing out of that plane, it will also shift to the side, putting more distance between the two objects that are hingedly joined together.
The two pins of each interface can either protrude from the same element (the link or the side plate) or protrude from different elements—i.e., one pin can protrude from the lateral side of the link while the other protrudes from the side plate. The same is true of the two guide slots of each interface: Either they can both be disposed in the same element (the link or the side plate) or one can be disposed in the lateral side of the link and the other in the side plate. For ease of distinction, the arrangement wherein the two pins protrude from the same element will arbitrarily be called the “paired arrangement,” and the arrangement wherein the pins protrude from different elements will arbitrarily be called the “unpaired arrangement.”
For ease of manufacture and assembly, preferably the paired arrangement will be used. That is, the two pins of each interface will protrude from one element and the two guide slots will be disposed in the other element. In other words, the hinge comprises:
In the paired arrangement, since the guide slots of each pair of guide slots are non-parallel, when one pin is forced to slide in one direction, the other pin of the pair is forced to slide in a different direction, thereby causing the first assembly to both turn and translate with respect to the link. By contrast, in the unpaired arrangement, moving one pin in one direction does not cause the second pin to move; rather, the second pin stays still because it is not disposed on the same element as the first pin. However, in both the paired and unpaired arrangements, the relative movements of the pins and slots causes the first assembly to both turn and translate with respect to the link. Consequently, in both arrangements, the link and first assembly are pivotable between a position at which they are relatively close together and a position in which they are further apart.
Although the two guide slots in each pair are angled toward each other, preferably the slots themselves do not intersect. In this way, there can be smooth, uninterrupted boundary walls for the pins to slide against. It is also preferred that at least those portions of the slots that guide the pins through the first 90 degrees of swing from the close-together position be substantially straight.
The first assembly can be connected to one object, while the second end of the link is connected to a second object. Both connections can be either direct or indirect (via one or more additional elements).
The connection between the second end of the link and the second object can be pivotal or nonpivotal. By a nonpivotal connection, it is meant that the second end of the link is integrally formed with, fixed to, or slidably attached to the second object, but the link is not be pivotable relative to the second object. If the connection is a pivotal connection, it can be beneficial to use the same type of pins-and-grooves arrangement as used at the first end of the link. In that way, two objects that are coplanar when in the close-together position (e.g., the table top and leaf of a fold-over/drop-leaf table when in the leaf-extended position) can be folded back through approximately 180 degrees of arc with less chance of interference. Thus, in the fold-over/drop-leaf table example, if the first assembly is mounted to the leaf and the second assembly is mounted to the top, when the extended leaf is swung up to vertical by pivoting the first assembly 90° with respect to the link, the face of the leaf that is opposite the top when in the extended position (the “opposed edge-face”) not only turns to face downward (toward six o'clock), it simultaneously moves to the side. Then the upstanding leaf can be folded down, onto the top, by forcing the link to pivot 90° with respect to the second assembly. While traversing this second 90° turn, the leaf's opposed edge-face raises up as it turns, and ends up facing the same direction as is faced by the top's opposed edge-face. By achieving this second (vertical) separation, the hinge can be mounted even a greater distance below the top surface.
In this last-mentioned embodiment, it is preferred that a restrainer be disposed in at least one of the four guide slots associated with the second end of the link, so that the pin in that guide slot is restrained from sliding in the guide slot until at least a predetermined threshold force is applied to the pin. In this manner, since the second assembly is restrained, the first assembly swings fully between the extended and folded positions before the second assembly begins to swing relative to the link, thereby causing the first and second assemblies to swing sequentially. It is contemplated that any type of pin restrainer can be used. Specific examples include an elongated piece of elastomeric material that extends at least part of the length of the guide slot, as well as a leaf spring having two ends and a convex central portion, the two ends of the spring being positioned against a side of the guide slot, with the convex central portion protruding into the center of the guide slot. I contemplate that other types of restrainers, such as compression springs, torsion springs, cantilever springs, interference fits between parts, and the like, could also be advantageously used to practice my invention. In each of the foregoing examples, the restrainer element(s) should preferably be positioned in or adjacent to one or more of the guide slots. Most preferably, restrainers will be disposed in guide slots associated with both sides of the second end of the link, not just one.
To add strength to the hinge, it is preferred that there be a first projection extending from one end of the link and that the first assembly comprise a first end plate having a stop slot that cooperates with that projection. There is preferably also a tab that protrudes from each member of the pair of second side plates, in combination with slots in each lateral side of the link. With the first assembly being pivotable relative to the link between an extended position and a folded position, these elements are so arranged that further pivoting of the first assembly relative to the link beyond the extended position is limited by abutment of the first projection of the link against the stop slot of the first end plate (at a first “stop point”) and/or by abutment of the notch in each lateral side of the link against the tab of each of the first side plates (at a second stop point). In this arrangement, the stress on the hinge is concentrated at the stop points, rather than the pins, when the leaf is in the extended position. This provides the hinges with a greater mechanical advantage and distributes the resulting stresses over a larger area than the pins. Accordingly, the hinge is able to support greater loads. For example, when a hinge according to my invention is used in a fold-over/drop-leaf table, each hinge is able to support loads in excess of 100 pounds applied to the leaf at a distance of ten inches from the hinge center of the hinge. Such high loads may be present when, for example, a person presses down on the leaf while either rising from the table or stretching across it in order to inspect something resting on the other side.
If the hinge includes one of the aforementioned assemblies attached to each end of the link, it is preferred that this arrangement of projection, tabs, and slots be provided at both ends of the link.
It is also preferred that each assembly in the hinge further comprise a mounting member, to which the side plates and end plate are attached. The mounting member should be configured to be attached to one of the objects that are to be hingedly connected, such as the aforementioned table top and leaf combination, a door and door frame combination, or the like.
The invention will be better understood by studying the drawings accompanying this specification, which depict a preferred embodiment of the hinge.
As shown in
In the preferred embodiment, hinge components 14a, 14b, 16a, 16b, 18a, 18b, and 20 are all made from 416 stainless steel which is heat treated to RC 42-45, yielding a tensile strength of 200,000 pounds. This material provides the hinge with great strength and reduces the chance of breakage if a heavy weight is placed on the extended leaf.
Protruding from the lateral faces of center link 20 are steering pins 22a and 22b, and hinge pins 24a and 24b, all of which extend in a direction parallel to the dynamic axes. (For ease of distinction, the pins that are closer together will arbitrarily be called “steering pins” and the outside pins will arbitrarily be called “hinge pins.”) These pins can vary in size and material, and they can be integral with the center link or they can be the opposite ends of a cylinder that is slidably mounted in a through-hole in the link. As one example of the latter embodiment, each cylinder can be a 1″×3/32″ stainless steel cylinder, having a tensile strength of 160,000 pounds.
The center link 20 further comprises first and second projections 28a and 28b, and stepped portion 26. Stepped portion 26 is formed by a notch in each lateral side of the link.
Each of the side plates 16a, 16b, 18a and 18b includes two non-parallel guide slots and one tab. For example, side plate 16a includes guide slots 32a and 34a and tab 36a, and side plate 16b includes guide slots 32b and 34b and tab 36b. Each of the side plates further includes a tongue 42. Finally, each end plate 14a and 14b includes two notches 44 and one stop slot (38a and 38b, respectively).
The relationship among the parts can be seen in
In mounting members 12a and 12b preferably include features to facilitate assembly, disassembly, and attachment to an object. As shown in
As noted above, short guide slots 32a and 32b are non-parallel with respect to long guide slots 34a and 34b. In each pair (e.g., 32a and 34a), the slots are angled toward each other, growing closer together in the direction running from the link toward the adjacent end plate. For each side plate 16a, 16b, 18a, and 18b, if a center line of the short slot 32a and 32b were extended far enough beyond the slot ends, that center line would intersect the long slot at a location intermediate its ends. The acute angle of intersection is preferably in the range of about 55 to 60 degrees. Preferably—as shown in the drawings—in each pair, the short guide slot (32a or 32b) is located closer to center link 20, while the long guide slot (34a or 34b) is located closer to its adjacent end plate (14a or 14b). As a result, when one pin on a side plate is forced to slide in one direction, the other pin on the same side plate is forced to slide in a different direction. For example, when mounting member 12a is turned relative to center link 20, steering pin 22a is forced to slide in guide slot 32a, while guide pin 24a is forced to slide in a different direction (i.e., along a nonparallel vector) in guide slot 34a. This motion causes cage portion 10a to both turn and translate with respect to center link 20. Consequently, mounting member 12a not only rotates relative to center link 20, but also moves slightly away from the other mounting member 12b. This simultaneous translation and pivoting movement reduces the need for a clearance gap between objects attached to mounting members, such as between the table top T and leaf L depicted in
I have found that when using a fold-over/drop-leaf table of the type depicted in
While the invention has been explained by a detailed description of a specific embodiment of it, it is to be understood that various modifications and/or substitutions may be made without departing from the spirit of the invention. For example, some or all of the pins (22a, 22b, 24a, and/or 24b) may be disposed on the side plates (16a, 16b, 18a, and/or 18b) rather than on the center link 20, with the corresponding guide slots (32a, 32b, 34a and/or 34b) disposed on the center link 20 rather than on the side plates. In other words, the placement of some or all the pins and guide slots can be exchanged. Accordingly, the invention should not be deemed limited by the detailed description of the embodiments set out above, but only by the following claims.
